COMBINED STORM AND WASTEWATER TREATMENT

Transcription

ADVISOR – ELZBIETA PLAZA
KTH Architecture and
the Built Environment
COMBINED STORM AND WASTEWATER
TREATMENT SYSTEM FOR ESTERO DE
VALENCIA, SAMPALOC , MANILA,
PHILIPPINES
Trina Go Listanco
March 2008
TRITA-LWR Master Thesis
ISSN 1651-064X
LWR-EX-08-09
© Trina Listanco 2008
Master Thesis
Department of Land and Water Resources Engineering
Royal Institute of Technology (KTH)
SE-100 44 STOCKHOLM, Sweden
Combined Storm and Wastewater Treatment System for Estero de Valencia, Sampaloc, Manila
ACKNOWLEDGEMENTS
My sincerest gratitude to the following persons and organizations; without them this thesis work would not have
been possible…
To the Swedish Institute (Si) and Swedish International Development Agency (SIDA) for the MKP scholarship grant
and the travel grant to complete the EESI Master programme in KTH
To the University of the Philippines, Diliman, College of Social Sciences and Philosophy, Department of Geography
for the opportunity to pursue and explore different tracks in applied geographies and other allied disciplines
To my adviser, Elzbieta Plaza for many encouragements and valuable advices
To Stig Morling and Bengt Hultman for very helpful and stimulating comments and discussions
To Francisco Arellano Jr. of Maynilad Water Services Incorporated (MWSI) for generously accommodating my
request to access some relevant data for this thesis
To Engr. Lucilo Ilio, Engr. Antonio Abayon and Engr. Remigio Abando of the Flood Control Division Central
Manila of Metropolitan Manila Development Authority (MMDA) for sharing data, thoughts and time in Manila City
To the helpful and progressive Barangay Officials, Council members and residents of EDV catchment
To the Varga family especially to Andras and Martin, for technical support and inspiration
To friends, Richard Ian Soliman, Miao Guofang, Amanuel Tecle, Pooja Yadav, Rosa Castillo, “Jun” Ballesteros and
Kristian Saguin for their various support and prayers
To my parents, Eddie and Anabella for everything
And to Endre Balogh for all his time and kindness
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SUMMARY
This thesis begins by presenting and briefly discussing the complex context and the rationales for a combined storm
and wastewater treatment system for Estero de Valencia (EDV) catchment in Sampaloc, Manila e.g. lack of
wastewater treatment infrastructures and its conjunctions with local flooding and pollution. Although, the functions
of the narrow, polluted and heavily transformed creek (EDV) is continuously being contested by several sectors, the
goal of the proposed treatment system is to improve the quality of water discharged into the estero according to the
prescribed standard of DAO 35, for Effluents into Inland Waters Class C. The paradigm introduced in this work
views drains as potential sites for wastewater treatment which could save capital costs, benefit the local communities,
contribute to improvement of environment and alleviate local flooding hazards. The methodology for the design
process involves a review of existing technologies and primary and secondary survey of study site profile including
physical and socio-economic (willingness to pay) parameters. Since physical wastewater parameters were not
measured on-site in this thesis, several estimations on wastewater constituent concentrations and loadings were done.
The resulting proposed treatment system is composed of “in line” physical and “2 step biological treatment”
methods. Different variations are also presented including possible vegetated submerged bed (VSB) installations in
the process sequence. The designs and theoretical performances i.e. BOD and TKN removal are modeled based on
functions and guidelines provided in textbooks. The proposed treatment units come with implementation
procedures and some risk management plans. This thesis however, can not provide exact costs and financial
schedules for the proposed treatment system, but attempts in giving an “idea” of how the system can operate with
limited financial resources. A willingness-to-pay (WTP) survey was done in the EDV catchment to elicit a theoretical
amount collectible from the residents for the operation and maintenance of the proposed system. This thesis needs
pilot-studies to validate the modeled results and performances an can be further strengthened by other assessment
tools, e.g. EIA and LCA, and through “integrated water cycle planning and management for “building water sensitive
cities”. (Wong, 2008)
SAMMANFATTNING
Detta examensarbete presenterar och diskuterar kortfattat de komplexa möjligheterna och rimligheten i kombinerat
dag- och avloppsvattensystem för Estero de Valencia (EDV) avrinningsområde i Sampoloc, Manila, bl a utifrån
avsaknad av infrastruktur för avloppsvattenrening och dess knytning till lokala översvämningar och föroreningar.
Fastän funktionerna för den smala, förorenade och starkt belastade bäcken (estero) kontinuerligt har bedömts av
olika sektorer har målet med det föreslagna behandlingssytemet varit att förbättra kvalitén för vatten utsläppt till
bäcken enligt den föreskrivna standarden DAO 35 för utgående vatten till inlandvatten klass C. Lösningen
introducerad i detta arbete ser dräneringdelar som pontentiella platser för avloppsvattenrening vilket inbesparar
kapitalkostnader, är till fördel för det lokala samhället, bidrar till förbättring för miljön och minskar lokala
översvämningsproblem. Metodiken för utformningen involverar en översikt av existerande teknologier och en första
och andra bedömning av den studerade platsen, inkluderande fysiska och socio-ekonomiska (betalningsvilja) faktorer.
Eftersom fysiska avloppsvattenparametrar inte mättes på plats i detta examensarbete genomfördes flera bedömningar
av avloppsvattens sammansättning med hänsyn till koncentration och belastning. Det framkomna föreslagna
behandlingssystemet består av på plats genomförd fysikalisk och 2-stegs biologisk behandlingsmetodik. Olika
varianter presenteras också inkluderande beväxta nedsänkta bäddinstallationer (VSB) i processtegen. Utformning och
teoretisk bedömning av resultat modelleras utifrån samband och riktlinjer från textböcker och leder till
genomförandeprocedurer och några riskplaner för förvaltning. Detta examensarbete kan inte tillgodose exakta
kostnader eller finansiella scheman för det föreslagna behandlingssystemet utan avser att ge en idé om hur systemet
kan drivas med begränsade resurser. En enkät om betalningsvilja genomfördes i EDVs avrinningsområde för att
bedöma en teoretisk summa som skulle kunna insamlas från de boende för drift och underhåll av systemet.
Examensarbetet behöver kompletteras med en pilot-studie för genomförande av det föreslagna och utformade
systemet och kan ytterligare utvärderas med hjälpmedel som EIA och LCA och genom planering och förvaltning av
integrerad vattencykel vid byggande av vattenkänsliga städer. (Wong, 2008).
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ACRONYMS
ADB
BRGY
BOD
CN
CSWWTS
CVM
CSO
DAO
DENR
DPWH
EDV
EMB
EO
HH
HLR
HRT
JICA
MTDP
MMDA
MWSS
MWSI
MWCI
NRW
NSWC
PD
PRRC
RA
RBC
sBOD
STP
SpTP
SWMM
TKN
VSB
WWTP
WWTS
WTP
WB
Asian Development Bank
Barangay
Biological Oxygen Demand
Combined BOD removal and nitrification
Combined storm and wastewater treatment system
Contingency Valuation Method
Combined Sewer Overflow
Department Administrative Order
Department of Environment and Natural Resources
Department of Public Work and Highways
Estero de Valencia
Environmental Management Bureau
Executive Order
Household
Hydraulic loading rate
Hydraulic retention time
Japan International Cooperation Agency
Medium Term Development Plan
Metropolitan Manila Development Authority
Metropolitan Waterworks and Sewerage System
Maynilad Water Services Incorporated
Manila Water Company Incorporated
Non revenue waters
National Solid Waste Commission
Presidential Decree
Pasig River Rehabilitation Commission
Republic Act
Rotating biological contractor
soluble biochemical oxygen demand
Sewage Treatment Plant
Septage Treatment Plant
Storm water Modeling Module
Total Kjeldahl Nitrogen
Vegetated submerged bed
Wastewater treatment plant
Wastewater treatment system
Willingness to Pay
World Bank
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Acknowledgements .............................................................................................................................................. iii
Summary ................................................................................................................................................................ v
Acronyms .............................................................................................................................................................. vi
Appendices............................................................................................................................................................ ix
Abstract ................................................................................................................................................................ 10
Introduction and Background ............................................................................................................................ 10
The Esteros of Manila: Urban Landscapes and Histories ................................................................................. 10
Actors, Efforts and Policies .............................................................................................................................. 11
Study Scope and Site......................................................................................................................................... 12
Topography ................................................................................................................................................ 13
Urban Hydrology and Drainage Network.................................................................................................... 13
Climate ....................................................................................................................................................... 17
Population .................................................................................................................................................. 18
Water sources, Water use and water supplied .............................................................................................. 18
Income levels.............................................................................................................................................. 18
Informal Communities................................................................................................................................ 18
Solid Waste ................................................................................................................................................. 19
The Research Problems and Project Rationales ............................................................................................... 21
Financial, spatial and institutional limitations to establish centralized sewerage treatment system....................... 21
Conveyance of untreated storm and wastewater through drainage system into the Estero de Valencia (EDV) and
the consequent flooding ................................................................................................................................... 21
Lack of systematic treatment to improve water quality of EDV ........................................................................ 22
The Objectives..................................................................................................................................................... 23
Methodologies and limitations ........................................................................................................................... 23
Characterization of load for years 2016 and 2025 ........................................................................................ 24
Characterization of load for years 2016 and 2025 ........................................................................................ 25
Flow rate estimation:................................................................................................................................... 25
Rainfall Data Projection .............................................................................................................................. 25
Wastewater Production Estimation Dry Weather Flow ............................................................................... 25
GIS and Storm Water Management Model (SWMM) ................................................................................. 27
Wastewater Characterization: BOD and the TKN load ............................................................................... 28
Willingness to pay survey ............................................................................................................................ 28
Other limitations .............................................................................................................................................. 29
Review of Related Literature............................................................................................................................. 30
Definitions and Concept background.......................................................................................................... 30
Principles for Solids separation ................................................................................................................... 31
Principles for Total Suspended Solids Reduction......................................................................................... 32
Principles for Biological Oxygen Demand Reduction .................................................................................. 34
Principles for Nitrification and NH4-N Removal......................................................................................... 35
Principles for Phosphorus Reduction .......................................................................................................... 37
Principles for Total Coliforms Reduction .................................................................................................... 38
Discussion on relevant Biosolids Management ............................................................................................ 38
Review on Management and Public Acceptability of Wastewater infrastructures.......................................... 42
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Results and Discussions ..................................................................................................................................... 44
Estimation of “Average Rain event for 2016 and 2025”.................................................................................... 44
Estimation of Dry weather flow rates and Wet weather flow rates for 2016 and 2025 ....................................... 44
Dry weather and Wet weather Flow rates in Profiled Manholes ........................................................................ 44
Treatment Goals............................................................................................................................................... 44
Optimal Site Selection ...................................................................................................................................... 45
Process Selection and Choice............................................................................................................................ 48
Why drilled metal plates for inlet screens? ................................................................................................... 53
Why tangential screens for fine screenings? ................................................................................................. 53
Why Rotating Biological Contractors (RBC’s)? ............................................................................................ 53
Why “Biotower”?........................................................................................................................................ 55
Proposed Processes and Sequences and Variations ........................................................................................... 55
Process Identification and Sequence without VSB....................................................................................... 56
Process Identification and Sequence with Vegetated Submerged Bed (VSB)................................................ 57
Point of Debate: The Estero de Valencia as a natural wetland for protection or construction?..................... 63
Designs ............................................................................................................................................................ 65
Inlet screens:............................................................................................................................................... 65
Pre RBC – Post RBC filter screens.............................................................................................................. 65
Vegetated Submerged Bed .......................................................................................................................... 67
Rotating Biological Contractors................................................................................................................... 69
“Biotowers” ................................................................................................................................................ 79
Summary of Results .................................................................................................................................... 81
Willingness-to-Pay Survey................................................................................................................................. 81
Results: ....................................................................................................................................................... 83
Implications on pricing: .............................................................................................................................. 83
Implementation and Maintenance ..................................................................................................................... 86
Road Inlet Screens............................................................................................................................................ 86
Pre-RBC and Post-RBC Filters ......................................................................................................................... 86
Rotating Biological Contractors ........................................................................................................................ 87
“Biotowers”...................................................................................................................................................... 87
Costs and Risk Management.............................................................................................................................. 88
Possible Costs Schedules .................................................................................................................................. 88
Risk Management ............................................................................................................................................. 88
Typhoons ................................................................................................................................................... 88
Earthquakes................................................................................................................................................ 88
Nuisances ................................................................................................................................................... 88
Inordinate failures of RBC’s and “Biotowers” ............................................................................................. 88
Conclusion and Recommendations ................................................................................................................... 90
Summary of principles and approach ................................................................................................................ 90
Design Features................................................................................................................................................ 90
Recommendations ............................................................................................................................................ 91
References............................................................................................................................................................ 92
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APPENDICES
Appendix I...................................................................................................................................................... 1
Appendix II .................................................................................................................................................... 5
Appendix III .................................................................................................................................................. 7
Appendix IV ................................................................................................................................................... 8
Appendix V..................................................................................................................................................... 9
Appendix VI ..................................................................................................................................................11
Appendix VII ................................................................................................................................................13
Appendix VIII ...............................................................................................................................................15
Appendix IX..................................................................................................................................................17
Appendix X ...................................................................................................................................................19
Appendix XI.…………………………………………………………………………………………………..22
Appendix XII.………………………………………………………………………………………………….26
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A B S T RA C T
Estero de Valencia (EDV) catchment in Sampaloc, Manila is one predominantly low income-high density urban area,
drained and served by a polluted “minor tributary” to the Pasig River. Esteros are naturally part of the estuarial
network of Pasig River but have been controlled by flood gates and pumping stations have been functioning mostly
as a tributary, with relatively low levels of salinity. It has several flood prone subcatchments and non sewered
communities, the combination of which, among other issues results in particularly difficult situation for the
introduction of major sewerage infrastructure and a centralized wastewater treatment system. This thesis presents a
conceptual design of a combined storm and waste water treatment system idealized to address the need for
wastewater treatment appropriate for EDV catchment. The proposed system is a combination of reviewed
techniques reconfigured and redesigned to run parallel to the track of drainage channels. This work heavily relies on
collected and estimated primary and secondary information on both physical and socio-economic (willingness to pay)
parameters through qualitative and quantitative methodologies. The adapted “alternative” principles of
decentralized, energy conserving, small scale and operable systems yielded a multiple site, “inline” designs including
the following treatment processes and units: 1) inline fine and micro screening; 2) vegetated submerged beds (VSB);
3) rotating biological contractors (RBC); and 4) “biotowers”. All are designed to capture and reduce typical
wastewater constituents (TSS, BOD, TKN, P and Coliforms) continuously during “dry” and “average wet”
conditions until year 2025, to intercept the wastewater flows at certain points upstream or prior to drainage outfalls
and to “protect” Estero de Valencia and Pasig River. The designs and their implementation guidelines based on
theoretical performance and recommendations from literature resulted in the compliance to the current Philippine
effluent standards for Inland Waters Class C (DAO 35). As a whole, the system embodies an alternative approach
for wastewater treatment system replicable in other estero catchments in Manila or other high density urban drainage
catchment.
Key Words: low income high density combined storm and wastewater treatment; inline physical and
biological treatment; Estero de Valencia, Manila
INTRODUCTION
A ND
drainage channels which have been functioning as
floodwater drainage, sewers and transportation artery
since the last century. (Liongson 2000)
Even before the Spanish colonizers came to Manila,
the estuarial banks of the Pasig river basin have been
hosts to thriving communities, dependent on the
range of resources and services, these swampy areas
provide. Merchants who traded agricultural goods
with Arabs, Chinese and other local merchants
occupied the river estuaries of Bulacan and
Pampanga provinces in the north, (Fox 1961,
Liongson 2001). They are groups of people who
have settled in riparian banks known as the
“Tagalogs” from the word “taga-ilog” (river dwellers)
and “Capampangans” from people of “pampang”
(bays or banks). (Liongson 2001)
Colonization, industrialization and urbanization in
different regimes brought historical changes to the
estuarial environments. And they are most obviously
manifested in the esteros’ transformed morphologies
and functions. The rebuilding of Manila after the
Second World War was accompanied by urbanization
so immense (from 1948-1968) that “the extent of
urbanized areas had tripled in 4 cities and 13
municipalities”. (Commandante 1979 in Regis 2001)
But the infrastructures did not get accomplished as
rapidly. The development in land transportation tha
came with urbanization has contributed to major
changes in the estero landscape. Estero banks which
used to be hosts of fishing communities and
merchants became known as “stinking” and marginal
public spaces occupied by communities of informal
settlers identified with urban poverty and extra legal
B A C K G RO U N D
This section briefly presents general history and the
transformations of the estero landscapes of Manila
and their contribution to current issues of urban
flooding and water pollution. A brief physical and
socio economic profile of Estero de Valencia
catchment is presented including the important actors
and stakeholders in the study site.
The Esteros of Manila: Urban Landscapes and
Histories
Manila City, with a density of at least 40,000 people
for a square kilometer, (PRRP 1990-1995), was called
the “Venice of the Orient” in George Miller’s book,
“Interesting Manila” for the “system of connected
waterways flowing slowly across the gentle slopes of
the Spanish Colonial capital”. Manila’s “esteros” are
natural waterways of the estuarial network, the
“narrow tidal creeks at the expanse of Pasig River
Delta” (Liongson 2001). Local and official histories
depict how the embankments of the swampy areas
have been systematically or illegally reclaimed for
private residential, commercial or transportation
expansions, and have been “lost under the
metropolis”1. In the present Filipino quotidian
language, “esteros” most often means (un)maintained
Term was used by Mary Anne Ocampo to describe
current urbanism in Manila (in a state of “amnesia”)
that has forgotten long ties with water, swamps and
esteros. Article accessed through the Syracuse
University Magazine website, December 2007
1
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economies. Estero waters which used to be intertidal eco-systems have been reduced to sewage and
drainage channels which conveyed wastewater and
solid from the road drainages wastes year round.
Such urban conversion has been metaphorically and
literally described as the “turning of backs” of the
people from the estero waters. This idea is reflected
in the language used by the “Flood Control and
Management Division of the MMDA” to refer to
esteros or “open drainage channels.” The phrase
completely undermines socio-cultural and ecological
roles esteros play in the urban system.
Informal settlers along the banks of esteros who used
to claim the three (3) meter river easements of public
lands, have been consistently blamed for the demise
of these waterways. This is despite the fact that
direct solid wastes and raw sewage from the informal
estero communities represent only a small fraction of
what the rest of the urban population and institutions
systematically put into the estero waters. Esteros
have been become convenient sites for discharging
untreated storm waters, domestic and commercial
wastewaters (especially of non-sewered households
and establishments) and solid wastes including road
litter, not just of the informal estero communities but
of the entire drainage catchment. Volumes of
wastewaters and other loads are conveyed by the
drainage network untreated, into the estero.
This research is an attempt to propose a holistic
system or conceptual design not to entirely “fix” the
urban history, but to provide ideas and ways to
improve and current urban infrastructures and
wastewater treatment practice. This thesis calls for
elevating estero water quality and landscapes in
agreement with the principles of the Philippine Clean
Water Act of 2004.
wastewater characteristics were compared to the
Water Quality Criteria provided by the Department
Administrative Order 34 series of 1990 (DAO 34) for
fresh water. Most esteros have failed to meet
standards for several parameters. Although there are
differing stakes on esteros among state and local
community actors, esteros are generally accepted to
function solely or mainly as open channel to flush
untreated floodwaters of the catchment to the Pasig
River. This thesis calls for elevation of esteros’
functions from mere sewer and drainage outfalls to
“naturalized”2 urban ecological spaces with at least
“Class B”3 water status in DAO 34. Reclassification
of estero waters from Class C4 or Class D5 to Class B
waters will lead to stricter effluents standards set by
DAO 35, and possibly, to wider practice of water
reuse and recycling in the future.
As Sharon Beder has written, “standards should
therefore not be based on what technologies within
the paradigm can achieve but rather on what
decision-makers want to be achieved in the longer
term. This in turn will force technological
innovation.”6
This study takes Estero de Valencia (EDV)
catchment and drainage network as site for a
combined storm and wastewater treatment system.
The proposed treatment system aims to improve
water quality of Estero de Valencia without
compromising flood control functions of the drains.
Quantitative and quality approaches were employed
e.g. storm water management modeling (in Balogh
2008) and willingness to pay survey (WTP) to
propose and design an appropriate collection and
treatment system for the EDV landscape. The
resulting system integrates drainage network system
improvements, decentralized and continuous
wastewater treatment systems along and alongside the
drains with small community treatment units i.e.
VSB’s as “support” installations.
Actors, Efforts and Policies
A number of government agencies, organizations and
other actors with different stakes, interests and
involvement in estero spaces are enumerated Table 1.
In 1999, about a decade since the Pasig River was
declared “biologically dead”, the Philippine
government created an agency, through Executive
Order 54, “specially dedicated to rehabilitation of
Pasig” called the Pasig River Rehabilitation
Commission or PRRC. (Regis 2001) Short and
medium term measures have been identified to
address point and non-point pollution sources which
included the esteros or the “tributaries” to the Pasig
River, as major pathways of domestic wastewater and
solid wastes. In March 2007, a preliminary baseline
profiling was done on six (6) major esteros directly
draining into the Pasig River.
The Environmental Management Bureau (EMB) of
the Department of Environment and Natural
Resources (DENR) led the one-time, in situ sampling
in Estero de Binondo, Estero de Quiapo, Estero de
Valencia, Estero de Pandacan, Francisco River, San
Juan River and Estero de Guadalupe Nuevo. The
Naturalized meaning non-alienating, people
involved in shaping meanings and strategies regarding
environment and living with the environment
3 “Class B” or Recreational Water Class I: for primary
contact recreation such as bathing, swimming, skin
diving, etc. (particularly for those designated for
tourism purposes) in Water Quality Criteria for Fresh
Water, DAO 34, series of 1990
4 “Class C” waters: include fishery water, recreational
water class II, industrial water supply class I in Water
Quality Criteria for Fresh Water, DAO 34, series of
1990
5 “Class D” waters: for agriculture, irrigation,
livestock watering etc; Industrial Water Class II (e.g.
cooling, etc) and other inland waters by their quality
belong to this classification
6 On sewage engineering paradigm, in article
“Technological Paradigms”
2
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Table 1. Actors and stakeholders of Estero de Valencia catchment system (estero water way, drains, roads and
easements)
Agency
Metropolitan Manila
Development Authority
(MMDA)
Department of Public Works
and Highways (DPWH)
Description / Mandate
mandated to manage and maintain road drainages, estero waterways and
pumping stations for flood control
charged for national roads and drainages maintenance; concerned with
flood control functions and roles the esteros play as major open waterways
for flood control and drainage systems
Department of Environment
and Natural Resources
(DENR) and Pasig River
Rehabilitation Commission
(PRRC)
primarily concerned about esteros and Pasig River ecology remediation,
sets standards for effluents and water quality criteria.
Metro Manila Waterworks
and Sewerage System
(MWSS)
assigned the task of assuring and overlooking the water delivery and
sewerage systems in the National Capital Region (NCR) and selected
surrounding provinces
Maynilad Water and
Sewerage Incorporated
(MWSI)
a private water utilities concessionaire (Manila City zone): for distributing
potable water and maintaining (or expanding) existing sewerage services,
indirectly use esteros and road drainages e.g. leaks of non revenue waters
from water supply pipes and untreated discharges of non-sewered clients
Manila City Government
including local community
government units
(Barangays)
Informal communities along
and in the esteros
represents, protects and governs the public including the informal
communities; needs capacity building for establishment of local sanitation
systems
obvious manifestations of severe and worsening housing backlog in Metro
Manila and the environmental injustices inherently interconnected with urban
primacy, rural poverty, land tenure issues and poverty; communities that
have been “legitimized” through their inclusion in the “barangay” – the
smallest political unit in the Philippines; some are more organized than the
others but most remains threatened by political and environmental hazards
of living in filthy, cramped spaces, and of having difficulty to access public
utilities and services, and of State evictions; among the most vulnerable
sectors to conflagrations and water borne diseases on top of persistent
insecurity from lack of land tenure; “scapegoats” for solid wastes disposal
into the estero waterways; theirs are also among the major stakes for estero
space and estero ecology and their concern speaks of a living space, of a
temporary home and opportunities for survival
Study Scope and Site
Estero de Valencia and its catchment was purposively
chosen for this study because apart from being
identified by the PRRC to be among the six (6) “key
minor tributaries” and point sources of pollution to
the Pasig River, it typifies the kind of aging drainage
and sanitation infrastructures, population and
household densities and their consequences in many
other areas in Manila City. The combinations of a
number of natural factors and products of historical
development e.g. minimal slope gradient, rapidly
growing population, increased solid waste
production, and historical reclamations of swamps,
have made EDV catchment among many low lying
areas with low to middle income households
frequently flooded. Like many parts of Metro Manila,
EDV catchment is only partly served by sewer lines.
Those which are connected to a kind of sewerage
system are part of only 8% of Metro Manila’s total
population. (SEA Presentation, World Bank) Those
not served by sewers are let to dispose domestic
wastewaters and rain water through roof-leaders
(down sprouts), into the drainages clogging inlets and
conduits.
12
Most households rely on individual or collective
septic tanks, but a number of households, especially
among informal communities live without any.
Those without septic tanks discharge raw wastewater
directly into the drainages or to EDV itself. Informal
communities along the Estero de Valencia easement
referred to as “estero communities” in this study,
total to about 300 families7 and they represent a
distinct wastewater stream to EDV. This wastewater
stream includes domestic solid wastes, and is
discharged into the Estero de Valencia waters
through shallow and narrow pipes from households.
Thus, the characteristics of wastewater streams in the
EDV drains is a blend partially treated sewage, grey
water, raw wastewater and solid wastes similarly as in
many other district drainage catchments in Manila.
The proposed wastewater treatment system offers
concepts and designs to handle these flow streams in
the EDV drainages, and can be adapted or replicated
in many other estero drainage or river catchments in
Manila and perhaps other provinces in the country.
The detailed physical and socio-political profile of the
EDV catchment follows.
Today, the total drainage catchment area of Estero de
Valencia is 256.81 hectares. Its upstream areas reach
Quezon City, which covers around 25% of the entire
channeled catchment area. The slope is steepest at
this northernmost portion and substantially
diminishes from the Cebu Street. One among many
other areas with lowest gradients is what used to be a
swamp in the central portion of the catchment (green
circle in Fig. 4). It is where rain water naturally
accumulates and frequently floods.
The southeastern portion of the EDV catchment
which is separated by the central ridge (red circle in
Fig. 4) was where a swamp enclosing Pureza and
Hippodromo Streets along Ramon Magsaysay
Boulevard was. (blue circle in Fig. 4) It was
developed to be “drainage district 30N” in 1950’s.
This area is has been reclaimed and made to be
drained by a lateral now called “NL 054”.
Urban Hydrology and Drainage Network
The drainage block of Estero de Valencia is primarily
residential with a number of small scale businesses
and schools. For most parts of the drainage
catchment, sewage together with grey water is
partially treated in septic tanks and then disposed of
through the drainages and into the EDV without
further treatment. The drainage network is thus
described to be a “combined sewer and drainage
system”.
In general, the drainage network was designed to
follow the natural topography, i.e.slope and aspect, of
the catchment except for the swamps that were
reclaimed and refurbished with drainage pipes.
The current drainage network design is composed of
five (5) drainage laterals coded as: NL 049, 050, 051;
and a main drainage along Visayas Street, coded “DM
10” or Drainage Main 10. This drainage main
discharges into the EDV at “Manhole 193”. The
profiles of these drainages are summarized in Balogh
(2008) and can be requested from certain Philippine
authorities.
The Estero de Valencia drainage catchment has four
(4) major geographic storm and wastewater flow area,
where treatment systems can be installed independent
of each other or in series.
Topography
Prior to the development of the Estero de Valencia
drainage block, “the natural watershed of Estero de
Valencia covers an area of 164 hectares”. (DPWH
1952) To present, the more elevated areas are found
on the northern portions along the streets of Santol
and Balic-Balic and G. Tuazon. From there, it slopes
abruptly towards a low lying basin which used to be
large swampy area with an elevation range of 9.60 to
11.0 meters--- below the mean water level of the
Pasig River. (Fig. 2) Thus, prior its reclamation and
to the installation of the Visayas Drainage Main and
the pumping station, this swamp has been
continuously under water. (DPWH 1956) Three (3)
more pocket swamps in the EDV catchment were the
basis for the planned development of the Estero de
Valencia drainage block (Figure 3).
Fig. 1 Different wastewater sources and streams into EDV: road drains for domestic grey waters; narrow aisles
between houses as make shift septic tank; and communal septic tank, Photos taken August-November 2007
7 Compiled from interviews and survey from
Barangay Chairmen of Barangays along Estero de
Valencia: Barangay 421, 422, 423, 424, 425, 576, 633,
634, 636, 628.
13
Trina Go Listanco
TRITA LWR MASTER
Fig. 2 An exaggerated (10
times) topographic image
of EDV catchment, Sampaloc, Manila in 3D, with
the Pasig River on the
foreground
Quezon City
Fig. 3 Plan showing the
1956 land cover and
drainages of Estero de
Valencia
catchment
(DPWH 1952)
14
Quezon City
Fig. 4 Map shows slope of the EDV catchment (Not scaled). Middle ridgeline (red circle)
cuts the catchment into the northern and southern slopes. The northern slope naturally
drains towards the swampy and low lying area of Visayas St., and the southern slope drains
towards the Ramon Magsaysay Boulevard. (DPWH 1956)
15
Trina Go Listanco
TRITA LWR MASTER
Fig. 5 Photos showing
conditions of: 1) domestic
wastewater pipes directly
connected to drainage
lines
(top
left)
2)
combined drainage and
sewers along narrow
alleys
in
informal
communities (top right)
3) clogged drainage inlets
(bottom left) and 4)
DM10 outfall in EDV
almost
completely
full/submerged (bottom
right, lower center of
image)
Photos taken near Loreto
St. and DM10, September
2007
Fig. 6 Photos of: 1) cluster
of informal houses along
the EDV easement and
Quintina Street (top left
and right) 2) a child
standing
on
EDV
easement in front of his
make shift house and an
overhanging
structure
(bottom left) and 3)
informal
estero
community in front of the
EDV Pumping station,
supplied with drinking
water
through
black
rubber tubes hanging on
the ester walls along the
yellow fence (bottom
right) Photos taken in
August and September
2007.
16
(PAGASA) 8. Type I climate subtypes “has two
pronounced seasons” associated with the monsoons.
Generally, the dry season begins from November
until April. The rest of year is wet. The Estero
Aviles Pumping Station (nearest pumping station,
west of the Estero de Valencia) has been regularly
collecting rainfall data in rain gauges since 2006. This
hourly rainfall profile was used to create rainfall
scenarios for Estero de Valencia catchment. The
graph below summarizes the 2006 rainfall data in the
Aviles Pumping Station. Projections or prognosis of
average rainfall events for 2016 and 2025 are
presented in detail in the thesis of Balogh (2008).
The first major inflow is through the DM10 Visayan
Drainage Main from north of the catchment, to
which at least 3 laterals (NL049, NL050 and NL51)
drain to; channeling waters from the streets of
Negros, Cebu and Leyte respectively. Collectively
they are discharged to EDV at Outfall 02. This
whole region is not served by the MWSI sewer
network. An “un-profiled” lateral from Luzon
Avenue flows directly into the EDV and is identified
as Outfall 01. A small scale in line treatment for this
lateral has been designed. A more realistic design can
be accomplished if this lateral will be re-surveyed and
profiled. The second major flow source comes from
the southeastern portion of the catchment through
the combined contributions of NL053 and NL054,
discharged to EDV through combined outfall near
“Manhole 225”. NL 054 reaches the south eastern
most part of the subcatchment including areas along
the Pasig river bank. Parts of these drainage areas are
served by the existing MWSI sewer lines but for
design purposes, these were assumed to be nonexisting or non-functioning. The third flow sources
are contributions from un-profiled/ un-coded,
smaller laterals that drain directly to the Estero de
Valencia. All relay storm waters, raw and partially
treated sewage waters. The discharges of these
outfalls have been estimated based on prescribed
standards for canals and slope characteristics of their
original drainage design. Estimations were done in
Balogh (2008). And these “Outfalls” are identified
along the streets of:
Annual rainfall 2006
600
505,95
500
418,728
Depth [mm]
400
287,431
300
230,125
200
152,629
100
102,814
86,582
57,456
28,808
3,183
18,144
0
0
1
2
3
4
5
6
7
Month
8
9
10
11
12
Fig. 7 Graph shows the accumulated rainfall for each
month in the year 2006
Annual rainfall exceedence 2006
0,
1;
5
31
600
500
73
0,
5;
3
30
50
60
70
1
1
1
1
2
40
80
80
;
20
70
;
10
60
;
0
50
;
20
;
0
5
15
10
;
100
40
;
200
30
;
300
1;
2;
27
3
5; ; 14 202
4
92
3
Duration [hr]
400
53
1) Outfall 03: Paltok Street
2) Outfall 04: Prudencio Street
3) Outfall 05: Constancia Street
4) Outfall 06: Lardizabal Street West
5) Outfall 07: Lardizabal Street East
6) Outfall 08: Valencia Street
7) Outfall 09: Nadelco Street
90
Intensity [mm/hr]
Fig. 8 Graph shows the number of hours of rain that
exceeded certain intensity based on the 2006 Aviles
rainfall data (Graphic representation by Balogh, 2008)
Together, these point sources or “drainage outfalls”
totaled 10; each of them with a delineated
subcatchment. These sources are taken to convey
both storm waters and “partially” treated wastewater,
as most of the households have claimed to have
individual or shared septic tanks and as some of the
households also claim to have sewerage connections.
The fourth flow source is from the formal and
informal households along the estero banks.
Wastewaters discharged as raw sewage, grey waters or
both, directly flushed to the EDV.
Daily pattern
1,80
De viatio n fro m averag e
1,60
1,40
1,20
1,00
0,80
0,60
0,40
0,20
0,00
Climate
0
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15 16 17 18 19 20 21 22 23
Hours
The Climate of Manila is classified as “Type I”
according to the Modified Coronas Classification
System of the Philippine Atmospheric, Geophysical
and
Astronomical
Services
Administration
Fig. 9 Graph average daily water consumption (Graph
adapted from figures of European daily consumption
pattern)
8 Modified Coronas Classification is a Philippine local
climate classification based on rainfall distribution,
PAGASA, DOST
17
Trina Go Listanco
TRITA LWR MASTER
Other Environmental hazards
clusters of 20-40 households11, or shanties and makeshift dwellings occupying partly or entirely, 0-20
meters of public or private spaces from easements of
the estero waterway. (see also Fig. 6)
Occasional overhanging structures like temporary
stores or kitchen extensions are set up by residents
along Estero de Valencia.
Their number is
considerably less compared to other estero
communities in Manila who have encroached and
covered almost the entire width of some other
esteros.
Although measures to reclaim the waterways and the
easements have been expressed, the realities of
housing shortages and bureaucracy make the
processes and the plans of relocating informal
communities not viable in the next five years,
according to an interview with an MMDA Engineer.
From interviews, estero residents along EDV have
come to settle illegally on easements, since 2-40 years
ago. Most of them found employment in Manila
suburbs as laborers.
Although some families raise 1 -2 chickens or ducks,
no full scale manufacturing and poultry raising
activities are present in the cramped spaces of the
household clusters. Unemployment can not be
officially determined as some are engaged in informal
economies. The average household size ranges from
5-6 persons per family. Interviews of barangay
community leaders reveal that 1 house in these
informal communities is usually is sometimes shared
by 2-3 families.
Drinking water to these informal settlements is
supplied through rubber tubes running from main
distribution pipes. They hang in the walls of the
estero and into household faucets. Some families
have water meters while others fetch water in plastic
barrels from neighbors or from public taps. From
interviews, all toilets, sinks and bathrooms are made
to drain directly to EDV.
According to interviewed residents, the lack of spaces
at home and bin stations, the irregular and infrequent
garbage collection in the informal communities are
few of the reasons why household wastes are
disposed into the EDV. Interviewed government
workers on the other hand, are convinced that the
illegal settlers along the esteros are hopelessly
undisciplined and should be relocated. Until now,
the estero banks remain contested by illegal settlers
and government agencies.
Tectonic hazards such as earthquakes and consequent
liquefaction in flood plain areas are relatively frequent
in Manila. But typhoons, tropical depressions and
tropical storms and associated hazards e.g. torrential
rains, strong winds, storm surges etc are more
frequent. These natural hazards must be considered
in any infrastructure design in the study site.
Population
The drainage block includes Zones: 43, 44, 54, 56-59,
62-63 and their Barangays. (Fig. 10) The total
population for all barangays in the EDV catchment
(including barangays whose areas are not entirely
within the EDV catchment boundary) is
approximately 136,373.9 The years 2016 and 2025
projections are from year 2000; and were calculated
“National annual population growth rate figures” of
2.36% from 1995 to 2000.10
Water sources, Water use and water supplied
The Estero de Valencia drainage block corresponds,
although not exactly, to the Maynilad Water Services
Incorporated (MWSI) Sampaloc Business Zones 1, 2,
5, 6, 7 and 9. (Fig. 11) A number of households use
private deep wells as supplementary sources of water
but from the survey conducted, their number is fairly
low. A total of 86 Barangays comprise the entire
EDV catchment but only a portion of Business Zone
6 is connected to the sewer network.
Water consumption in a day is expected to peak twice
(in the morning and in the evening) as in most cases
in other countries. (Fig. 9) For design purposes and
simplifications in this thesis, only the estimated
average flow rate of wastewater in drainage manholes
was used. The table for estimated daily water
consumption per barangay is presented in the
Results and Discussion chapter and summarized
in Table 15.
Income levels
Income levels in the EDV area are generally
categorized to be “low income”, except for the “Class
1 residential area in Piña Private Subdivision on the
east part of the catchment” (DPWH 1952). The
average household income for each barangay was
estimated in the willingness-to-pay survey. The
results of the survey are presented in the section
“Willingness-to-Pay survey” in the Results and
Discussion chapter, Table 51.
Informal Communities
The informal communities in EDV catchment vary in
extent and population. Some are more established
and more organized than others but typically, estero
communities along the Estero de Valencia refer to
11 “Households” are defined in the Philippines quite
similarly as in described in the website:
www.southampton.gov.uk/environment/developme
nt-control/planning-terms.asp as: “One person living
alone or a group of people (who may or may not be
related) living at the same address with common
housekeeping, sharing at least one meal a day or
occupying a common living or sitting room”.
Computed from the 2000 Philippine Census data
provided by the Manila City Barangay Bureau
10 Value was taken from the 2000 Philippine Census
Report, the latest Philippine National Census
commenced in August 2007.
9
18
Fig. 10 Barangay Map (numbers are BRGY ID numbers) of EDV catchment with manhole subcatchment data
layer (Data sourced from Samaploc Business Center, MWSI and Balogh 2008)
Solid Waste
for more characterization and measurements of solid
wastes parameters in EDV.
With the total population of EDV catchment, an
estimated 17,755 kilograms of garbage is produced
daily, a fraction of which finds its way to the estero
waters and are collected in the EDV pumping station.
Solid waste collection occurs daily in most barangays,
but interviews with local residents reveal that
collection trucks do not stay long enough to wait for
all residents to take out their garbage bags.
Solid waste generated per capita in Metro Manila is an
average of 0.5 kg per person per day. (ADB 2003)
This number does not reflect the variations of solid
waste production across varying income ranges in
EDV communities and households. Characteristics
of solid waste components, especially the amounts of
toxic compounds and elements are not available in
detail, but their effects and implications on the
selection of appropriate wastewater and biosolids
treatment facility is very important. This thesis calls
19
Trina Go Listanco
TRITA LWR MASTER
Fig. 11 Map showing
barangays
in
MWSI
Sampaloc Business Zones
within EDV catchment.
(Data
sourced
from
Samaploc Business Center,
MWSI and Google Map)
Collected solid wastes are transported to landfills and
dumpsites outside the city. No materials recovery
facility (MRF) in any of the barangays in EDV has
been noted in field surveys between August and
November 2007.
Solid waste (mis)management and the lack of
education about solid waste and wastewater treatment
systems at the community and household levels are
most usual explanations for the “estero problem”. In
general, resentment towards people who illegally
reside along the estero banks grow from the realities
that some of them dispose of their domestic wastes
into the estero, worsening the water pollution.
Empowerment and capacity building of the estero
communities were rarely mentioned in State
proposed solutions. The State solution to the issue
has been publicly announced several years ago as an
urban environment policy to “restore” the esteros
primarily by retrieving spaces from the “squatter
communities” and by reclaiming the banks and
easements of the demeaned rivers, or in simpler
words, displacing thousands of people and families.
Recent experiences in “rehabilitation” of public
spaces e.g. railroad tracks and pedestrian overpasses,
by government entailed massive displacement of
informal settlers that were often violent.
As
prescribed relocation sites become fully occupied,
government struggles to maintain order in these
contested spaces.
Since August 2007, the rehabilitation of esteros has
been fully mandated to the Metropolitan Manila
Development Authority (MMDA). According to
recent reports, a “task force” for streamlining the
process of relocating families has been set up. Amid
efforts to “clean” esteros, the water quality of the
waterway is never given much attention and priority.
Efforts to clean the estero meant only “dredging”
and maintaining its capacity to discharge untreated
wastewater and storm water into the Pasig River.
20
THE RESEARCH PROBLEMS
PROJECT RATIONALES
only be done during non-work and no-rush hours
and 40 percent of the West zone comprises
depressed areas with no septic tanks. Likewise,
the public has poor sanitation awareness and is
not keen on desludging their septic tanks.”
(World Bank, 2003 p. 29)
A ND
This section presents three research problems that
are very interrelated. They occur in combinations not
just in EDV catchment but in many other densely
populated cities and districts in the capital region.
Further, the report reveals that “the allocation for
sewerage and sanitation are sacrificed to address high
demands for water supply.
As consequence,
sewerage and sanitation have been relegated a small
portion of the budget despite having fives times the
investment cost for the water supply” (World Bank,
PEM, p. 23). According to the Medium Term
development Plan (MTDP) “investment trends in
sanitation have been increasing in recent years but are
due to decline in the near future”. (World Bank,
PEM 2003, p. 28)
A realistic scenario was described by the head of
Sewerage Department, MWSI in interview: “the
sewerage network upgrading is a priority project”.
However, no plans for network expansion and
inclusion of non sewered areas were mentioned.
According to the World Bank’s Projected Investment
Plan, the conjectural amount of Php 25 Billion per
year for physical infrastructure for wastewater and
sanitation, for the next 10 years would experience
constraints like insufficiency of funds, site and rightof-way acquisition, environmental and social
problems among others. Thus, it has recommended
a phased implementation schedule such as an up scale
model of a given system in Figure 13 which could
eventually be upgraded or built up into a full blown
wastewater treatment system in the future. Such
model features collecting and intercepting
wastewaters and diverting to a sewage treatment
facility, prior to discharge into creeks. It only
functions in the dry season, and is thus called a “dry
weather flow interceptor” (DWF). The framework
provides the foundations from which the proposed
wastewater treatment system in this thesis takes from.
This thesis address the limitation of the DWF
interceptor by designing a system that will possibly
treat wastewater flows even in average rain conditions
until 2025, and that can also be implemented in
phases. This paper addresses this issue by proposing
a continuous treatment system “in line” or along the
existing drainage network.
Financial, spatial and institutional limitations to
establish centralized sewerage treatment system
Republic Act (RA) 6234, the creation of the
Metropolitan Manila Waterworks and Sewerage
System Administration (MWSS) in 1971, delegated
(MWSS) as the primary enforcer to “construct,
properly operate and maintain water systems, for
drinking and others, sewerage, sanitation and other
public services vital to public health and safety in the
National Capital Region (NCR) including some cities
of nearby provinces.” It has been declared a policy
of the state that the establishment, operation and
maintenance of such systems must be supervised and
controlled by the State.12 But the privatization of
MWSS in 1997--- a strategy listed first among nine
conventional sources of funds financing sewerage
and sanitation program by a World Bank report13, led
to the creation of two concessionaires, Manila Water
Company Incorporated (MWCI) and Maynilad Water
Services Incorporated (MWSI). Each respectively,
handles the “East” and the “West” zones of Metro
Manila’s water pipes and distribution networks.
However, to present, many areas remain “nonsewered”; relying mostly on drainage lines to rid
domestic and commercial grey water and sewage.
(Fig. 14)
Estero de Valencia drainage catchment is partially
included in the MWSI west Business zone (Business
Zones 1, 2, 5, 6, 7 and 9), but only a limited portion is
served by the existing sewer line.
According to the World Bank Environment Monitor
Report 2003, the “privatization laid the foundation
for improvements in the sewerage and sanitation
services which experiences delays due to a number of
reasons, but specifically for MWSI:
“MWSI had difficult time in accelerating
desludging services because such services could
Conveyance of untreated storm and wastewater
through drainage system into the Estero de
Valencia (EDV) and the consequent flooding
Meanwhile, the existing drainage system of EDV is
expected to continue to convey at least about 130,000
peoples’ sewage and greywater; while draining about
256 hectares of low lying basin. The EDV drainage
network represents the underground channeled flow
streams of combined storm and wastewaters. The
five (5) profiled drainage laterals and a main drainage
line, ends in ten (10) identified outfalls relaying
untreated storm and wastewater into the Estero de
Valencia at different flow rates.
Law states that privatization of MWSS should not
be an option, but concessions were approved and
distributed in 1997
13 World Bank Philippine Environment Monitor 2003
p 29, recommended that national assistance and
training efforts concentrate on these nine areas: 1)
privatization, 2) internal revenue allotment, 3) special
levies, 4) development fees (permits, development
impact fees and groundwater protection fees), 5)
surplus funds, 6) sewerage surcharges, 7) property
tax, 8) credit and 9) other private sector finance
beneficiary cash contributions, contributions in kind
and user fees)
12
21
Trina Go Listanco
TRITA LWR MASTER
Storm water or run off quality and quantity in EDV
catchment are mainly dependent on land cover and
seasonal precipitation in the catchment. Qualities
and quantities of domestic wastewaters, including
solid wastes, can be generalized as mixture of grey
water, sewage, wastewaters from wet market place,
carwash services, restaurants and hair salons. No
large scale manufacturing activity was registered in
EDV.
The combination of storm and wastewater puts
enormous loads in the drainages, and aggravates the
flooding hazard vulnerability of the catchment. A
pumping station flushes untreated EDV waters into
the Pasig River and annually hauls about 360 cubic
meters14 of solid wastes with mechanical grits.
Symptoms an ineffective and overloaded drainage
system include local floods which manifest similarly
as “overflows” in clogged manholes and inlets
because of heavily silted drains, especially in the
monsoon season (June – early September).
Flooding is not simply a consequence of overloaded
drains. It is also the reason why wastewater treatment
projects can not be adequately funded yet. According
to the World Bank PEM, 2003:
Lack of systematic programme to improve water
quality of EDV
Section 8 of the Philippine Clean Water Act of 2004
states:
“Within five (5) years following the effectivity of
this Act, the agency vested to provide water
supply
and
sewerage
facilities
and/or
concessionaires in Metro Manila and other highly
urbanized cities (HUC’s) as defined in Republic
Act No. 7160, in coordination with LGUs, shall
be required to connect the existing sewage line
found in all subdivisions, condominiums,
commercial centers, hotels, sports and
recreational facilities, hospitals, market places,
public buildings, industrial complex and other
similar establishments including households to
available sewerage system: Provided, that the said
connection shall be subject to sewerage services
charge/fees in accordance with existing laws,
rules or regulations unless the sources had already
utilized their own sewerage system: Provided,
further, that all sources of sewage and septage
shall comply with the requirements herein. In
areas not considered as HUCs, the DPWH in
coordination with the Department, DOH and
other concerned agencies, shall employ septage or
combined
sewerage-septage
management
system.” 15
“Wastewater treatment facilities with large spatial
footprints can not be accommodated by high
density
low
income
suburban
areas.
Conventional sewerage projects and expansions
cannot be realized because of other urgent and
conduit issues like solid waste management, lack
of sewerage network, inefficient drainage systems,
water supply.” (World Bank, PEM, 2003, p. 29)
The Manila Third Sewerage Project (MTSP) is an US
$85 million-World Bank assisted initiative by the
Manila Water Company Incorporated (MWCI), for
building combined sewage-drainage systems,
modernized large scale septic tank de-sludging
program, education campaigns, off site and
underground sewage treatment facilities, from 2005
to 2010 in the “East Zone” concession. However, no
systemic counterpart project in the “West Zone”
been disclosed yet. This means that EDV catchment
and the rest of the “West zone” esteros will continue
to collect sewage. There are plans of upgrading the
existing sewerage network but because of the density
of built up area in Manila, the installation of
centralized sewage treatment system seems too costly
an option. Constructions of new sewer lines across
non sewered areas can be highly disruptive and
capital intensive. This idea is also reflected in the
Philippine Environment Monitor of 2003:
Flooding has been a perennial “experience” and a
familiar “reality” not just in the EDV catchment but
in Manila City in general. Drainage lateral, NL 049,
particularly manhole “iii 11A4197”, was especially
noted for “urgent works” because of frequent
clogging. (JICA 2000) According to local residents,
the low lying basin around Cebu and Pureza Streets
are usually flooded even with slight downpours of
rains.
The current conditions of the drainages and the
practices in drainage maintenance are the reasons,
challenges and opportunities for introducing a
wastewater treatment system along the drains without
compromising the capacity of drainages to discharge
storm waters. This thesis highlights that many
problems occur and accrue in the drainages, and thus
proposes solutions for it and in it.
“Even with highly urbanized cities, the
implementation of a conventional sewerage
project cannot be realized in the short term
because of other environmental concerns facing
the LGU’s such as solid waste management,
drainage, water supply etc.” (World Bank, PEM,
2003, p. 26)
14 Figure value for year 2006, taken from the Report
of Flood Control Division “Volume of Garbage
Accumulated and Uncollected from each Pumping
Station, MMDA
RA 9275: is the Philippine Clean Water Act of
2004
15
22
Aligned with the implementation of the Philippine
Clean Water Act of 2004, prioritization of
Government investments for sanitation and
principles of participative community development,
this project specifically aims to:
Traditional urban water management had physically,
philosophically and institutionally compartmentalized
water supply, sewerage and storm waters leading to
“sub-optimal outcomes”. (Wong 2008) There is thus
a need for a new paradigm that would allow
infrastructural development with goals of hazard
minimization and better urban ecology.
This thesis operates in a framework and contributes
to the establishment of new approaches to traditional
wastewater management, such that sanitation and
wastewater treatment technologies can provide
solutions based on pressing local realities not just for
“environmental protection from a threat but as a
valuable resource for the benefit of the
communities.” (Trejo 2007)
Figure 15 encapsulates flow paths and presents the
drainage system as a nexus of “wastes” sources and
environmental hazards (flooding and estero
deterioration) in which technological interventions
such as a continuous combined storm and wastewater
treatment system could be introduced. This paradigm is most useful for densely populated urban areas
without sewerage networks and with limited spaces
and funds for an off site and centralized wastewater
treatment plant.
Understanding the urban hydrology, drainage
profiles, water supply trajectories and community
sanitation practices is crucial to contextualize the
technological system that can optimize the existing
urban infrastructures and achieves an effective
continuous flow storm and wastewater treatment
system like an “in-line, integrated storm and
wastewater treatment system”. This thesis thus
addresses the following questions:
1) Propose wastewater and storm waters treatment
methods or combinations of methods to achieve the
standards for effluents to Inland Waters Class C in
the DAO 35. The proposed measures and systems
are primarily for reduction of four parameters and
wastewater constituents i.e. Total Suspended Solids
(TSS), Biological Oxygen Demand (BOD5), Nitrogen
(TKN) and Phosphorus and Total coliforms;
2) Design the unit processes, configurations and
installations to satisfy operational requirements of: a)
minimal capital/ infrastructural costs, area footprint
and skilled maintenance; and 2) flexibility to seasonal
variations in volumetric and organic loadings; for
several selected and optimal sites, along the existing
drainage network in EDV catchment appropriate for
until years 2016 or 2025; and
3) Propose implementation guidelines for management, operation and maintenance of the proposed
design e.g. treatment by-pass procedures, including
financial challenges according to amount willing to be
paid by residents.
M E T H O DO L O G I E S
AND
LIMITATIONS
A review of related literature was done on selected
technologies, published literature and models from
pilot or full scale treatment plant studies.
An
overview is presented in the section Review of
Related Literature. Because of the lack of regular
parameter
measurements
on
wastewater
characteristics and flows in the drainages on site, a
number of estimation had to be done based on
available information.
1) How can Estero de Valencia waterscape be
rehabilitated through an integrative wastewater
treatment system along the drainages?
2) What will be the features of an appropriate EDV
combined storm and wastewater treatment system,
considering aspects of the site’s physical and socio
economic geographies e.g. hydrology, wastewater
characteristics, public acceptability and sustainability?
THE OBJECTIVES
Ultimately this study embodies an alternative
paradigm for wastewater treatment system in EDV.
It views drainages as potential sites for wastewater
treatment which through appropriate technologies
can benefit local communities.
Fig. 12 Photo on left
shows grits and back hoe
used to rid the estero
pumping station of solid
wastes. Photo on right
shows wide assortment of
solid wastes trapped at the
closed gate of the
pumping station. Photos
taken in September 2007
23
Trina Go Listanco
TRITA LWR MASTER
Fig. 13 Development of drainage and sewerage infrastructure including an intermediate option for combined sewers,
taken from World Bank (2003) Philippine Environment Monitor 2003, p. 27
Fig. 14 Photo on the top left
shows typical connection of
house roof leaders and
domestic wastewater pipe
directly into the road drains;
photo on the bottom left
shows manholes along
Leyte St. (foreground) and
Visayas Drainage Main
behind; photo on top right
shows
resident
doing
laundry on the street and
disposing wastewater to the
drain and photo on bottom
right, is the Estero de
Valencia Pumping station.
(Photos taken, September
2007)
24
Characterization of load for years 2016 and 2025
The above mentioned estimated flow rates (dry and
wet) for each drainage conduit and manholes were
derived from SWMM model of Balogh (2008).
The loads in different manholes are calculated from
the estimated flow rates and the parameter (BOD and
TKN) concentrations. These data are estimated for
each profiled manhole in the EDV drainage system.
These projected figures for each manhole are
cumulative down the drainage lines. The manhole
information is the basis for optimal treatment site
selection and for treatment installations. For design
purposes, only the average flow rates and projected
concentrations for dry and wet weather were used.
Using the average flow rates introduces a number of
risks that have to be considered for implementation
and assessment of the designed treatment system.
Rainfall Data Projection
Storm water flow rates are based on interpolated
monthly rain distribution from the 4-year data base.
Available hourly rainfall data from year 2003-2006
was collected from MMDA-PAGASA rain gauge
station nearest the EDV catchment, “Science Garden
Station.” Estimation details are discussed in Balogh
(2008).
Another available hourly rainfall data source (year
2006) is from the adjacent pumping station, “Aviles
Pumping Station”. From the Aviles 2006 rainfall
data, the maximum and average rainfall event-curve
of 2006 was derived. The average and maximum
rainfall curves have been projected using the LogPearson Type III distribution (Chow et al 1988 in
Balogh 2008) for year 2025. The result yielded the
maximum intensity rain that can be expected to occur
until 2025 (inclusive of 2016).
Using the projected peak intensities for 2025, the
“design rain event” has been created and was used as
an input to the SWMM. The “design rain event” is
such a rain event which occurs once between 2006
and 2025. This design rain event was applied in
SWMM to get the maximum hydraulic loads in the
drainage lines. For the purposes of combined storm
water and wastewater, this “design rainfall event” was
considered a “by – pass” condition and is more
relevant for drainage pipe designs. According to
Balogh (2008) design rain event for until 2025 yielded
a maximum rainfall of 92.5 mm depth occurring in 1
hour. The design storm or rain event is presented in
Figure 16.
The “average rain events” for 2016 and 2025 have
been computed from the Aviles 2006 monthly hourly
rainfall data. (Fig. 17) A rank list of the rains in 2006
has been made using the ratio of maximum intensity
and average intensity that yielded the “maximum –
average rain intensity-duration” curve. These average
values have been used for designing the combined
storm and wastewater treatment system. Using these
average flow rate values introduces invalid
concentrations and loadings especially during times
of minimum and maximum daily wastewater
production.
Balogh (2008) has used one of many methods to
estimate and project rainfall for future scenarios.
These results are the only hydrological information
and prognosis accessible and available to the author
at the time of this writing. This complimenting thesis
work of Balogh (2008), including its projections and
recommendations were directly used and quoted.
Flow rate estimation:
The flow rate estimation is discussed in more detail in
the complimenting thesis: “GIS based Hydraulic
Model of Estero de Valencia, Manila Philippines” of
Balogh (2008). Flow rates along the drainages were
derived by identifying subcatchments of each
component drainage manhole.
Each drainage
subcatchment was identified and overlaid with the
barangay boundary data and with the MWSI zones
(with figures of supplied volume, billed volume and
NRW) to derive the wastewater production per
barangay and per subcatchment.
The estimation of wastewater production is discussed
in the succeeding paragraphs.
The barangay
population data and population projections were used
to estimate not just the wastewater production per
capita but also the average water consumption per
barangay for 2016 and 2025.
The dry weather flow rate in this thesis meant the
average daily wastewater production.
Without
rainfall, only domestic wastewater flows in the drains.
The dry weather flow varies within the day with
patterns of water consumption, and the supplied
water volume provided by the utilities company
(MWSI). This wastewater discharges are composed
of grey water, sewage (partially treated and raw) and
portions of water pipe leakages from households,
water pipes and establishments. For the treatment
system design purposes, only the “average daily
wastewater production” and flow rate was used,
equivalent to the dry weather flow rate.
The wet weather flow rate includes the rainfall in the
drains and is thus, the sum of domestic wastewater
production and the average rain projected for years
2016 and 2025. For treatment design, it is assumed
that the rainwater adds to the volumetric dry weather
flow, dilutes concentrations of average dry weather
flow constituents and adds other constituents e.g.
grease and oil. Safety factors used to account for
higher BOD concentrations in combined storm and
wastewater streams. Preliminary unit operations were
included and designed to handle additional loads
from “first flush” and other typical storm waters
constituents like grease and oils, organic and
inorganic sediments and solid wastes.
Wastewater Production Estimation Dry Weather Flow
Wastewater production in the EDV catchment was
derived from the MWSI (Sampaloc Business Center)
supplied volume data from 2004-2006. The data is a
summary of monthly supplied water volume for each
of the 9 constituent zones.
25
Trina Go Listanco
TRITA LWR MASTER
D
G
R
D
G
R
D
S
S
G
R
Drainage route downstream
with cumulative flow rate, drain
area and load
Decentralized
“inline” treatment
system installations
SP
Fig. 15 The framework of
“Inline
wastewater
treatment system” where
drainages are represented
to be sites of the problem
and
sites
where
interventions
can
be
introduced
SP
SP
S
Storm and wastewater on the drains:
D = Direct rain fall
R = run off
G = Gray water
S = Sewage raw
Sp = septage
The supplied volume measures the sum of client
billed volume and “non revenue waters” (NRW).
The NRW is composed of the illegally tapped water,
leakages and pipe losses. Sampaloc business zone
data reveals that only an average of 30% of the
monthly supplied volume is being billed or legally
paid for. And around 70% of the supplied volume is
NRW or “lost”.
Only 50% of the NRW was considered to be flowing
directly into the drains, the rest are assumed to be
supplied water that seeps through the ground or gets
evaporated.
Suppliedvo lume = 0 .30 billedvolu me +
It is assumed that the whole area of EDV is not
covered by the existing sewerage network of MWSI,
such that all sewage waters end up in the drainage
system. This assumption could be realistic, but can
introduce overestimations of loads in certain
manholes. The wastewater production was projected
for years 2016 and 2025 by adjusting the billed
volume values that represents water demand.
0.65Suppliedvolume = wastewaterproduction =
= 0.30billedvolume + 0.35 NRW
+ 0 .7 NRW
For a non conservative estimation of the wastewater
production in EDV catchment, all “used” water
ending up in the drainages was considered and thus,
65% (30% billed volume + 35% of NRW) of the
MWSI supplied volume in zones within the EDV
drainage catchment was used as total wastewater
produced.
26
The population was projected using the 2.36% annual
growth rate from Philippine Census of 2000 and so
were their equivalent wastewater production. In
barangays outside Manila city, and in barangays
without population data, the estimated wastewater
production was derived from the average wastewater
production per unit area per year. The estimation
assumes that the population density and wastewater
generation in the Quezon City is most likely the same
as in Manila City, but the fact is that, the barangays in
Quezon City are with lower population density. This
yields a probable overestimation of wastewater
production, but can be regarded as “safety precaution
and assumption” of the treatment system design. All
these methods were done with GIS tools for spatial
computing.
Note that a population-based estimation for
wastewater production in EDV (e.g. multiplying an
average wastewater production per capita of 150 liters
per capita per day, to the catchment population) was
not preferred because of the limitations in population
data available (latest publication was that of
Philippine Census 2000).
In some barangays the computed average water
consumption per capita is less than 100 liters while
others have values of more than 200 liters per day.
This value can be explained by the fact that in many
barangays, water supply connections are limited,
illegal or defective, while in others are properly
working and with meters correctly read. The 2.36%
national population growth rate (NSO, 2000), could
be in fact lower than the Sampaloc growth rate
figures. The income ranges and patterns of water
consumption and diet among residents also vary
widely. To account for a more accurate and realistic
wastewater flow volume, the water supplied data was
used as basis for this thesis.
Design storm for 2025
92.5
Intensity[m
m
]
100
80
60
40
20
10.9
4.4
4.1
3.4
4
5
0
1
2
3
Elapse d time [hr]
Fig. 16 Projected design rain events for 2025 Graph
results lifted from Balogh (2008)
Average rainfall for 2016
Intensity [mm]
10
9
8
6.5
6
4
2
0.3
0.6
0.5
4
5
1.3
1.7
1.7
6
7
8
0
1
2
3
Elapsed time [hr]
Average rainfall for 2025
Intensity [mm]
12
10.5
10
7.5
8
6
4
2
0.3
0.8
0.6
4
5
1.4
2
2
7
8
0
1
2
3
6
Elapsed time [hr]
Fig. 17 Graphs of estimated average rain events for
2016(top) and 2025 (bottom), lifted from Balogh (2008)
GIS and Storm Water Management Model (SWMM)
SWMM model results were lifted from Balogh (2008)
where a Digital Elevation model (DEM) was created
in GIS environment from the manhole elevation data
and topographical survey collected from the Study of
Existing Drainage Laterals (JICA 2000). From the
digital elevation model, hydrologic properties of the
catchment were derived e.g. flow direction and
accumulation were derived to delineate further the
subcatchments within the EDV catchment block.
(Fig. 18)
Surface topography interpolated from manhole
elevations and contours have inherent spatial errors.
The Storm Water Management Model (SWMM)
package (open source software from the U.S. EPA)
computes and models the channel flow in the
drainage catchment given a rain event. The SWMM
model can simulate hydrological events including dry
weather flow in drainage lines and flooding in the
catchment and its components.
Since not all
drainages were profiled, (especially the ones outside
Manila City administrative border) estimated slopes
and lateral cross sections had to be interpolated.
For 2016 projections, the 2006 billed volume was
increased by the national population growth rate of
2.36% per year such that the billed volume (the water
demand of increased population) is 10% more than
the 2006 figure, while the NRW is assumed to not
change.
0.75Suppliedvo lume 2006 = wastewater production 2016 =
= 0.40billedvolu me + 0.35 NRW
For the year 2025, the billed volume was projected
accordingly (with the population growth rate) as well,
such that the billed volume is 18% more than in
2006. The NRW for 2025 is assumed to have
decreased by 2 % from 2006, to account for
possibilities of infrastructural improvements.
0 .81 Suppliedvo lume 2006 =
= wastewater production 2025 =
= 0 .48 billedvolu me + 0 .33 NRW
27
Trina Go Listanco
TRITA LWR MASTER
The model considered pipe profiles as they were
designed. In reality, the drainage pipes are mostly
filled with silt and different sediments and solid
wastes. It is important thus to the implementation of
the proposed inline treatment design, that drainage
conduits are cleared and maintained for treatment
operations. More recommendations for drainage
maintenance are provided in Balogh (2008).
Table 2. Metadata for Wastewater Production
Estimation:
Wastewater Characterization: BOD and the TKN load
Since no exact and on site measurements of wastewater quality parameters are available e.g. drainage
wastewater quality. A survey of published figures on
typical sewage and wastewater characteristics from
other countries were gathered and taken as proxy
values for EDV catchment. Specifically, for TKN
production per capita, the published values for Japan,
(1-3 g TKN/ person*day) was used to estimate for
TKN production in EDV. Japanese diet (rise based
and fish proteins) closely resemble, at least the
Filipino food consumption.
BOD and TKN loading in a manhole were estimated
by using published data. Qian et al (1998) provided a
production rate in Metro Manila of 40 g BOD/per
capita per day; and Metcalf and Eddy (2003)
presented the average Japanese TKN production
rated per capita per day of 1-3 g TKN/ capita per
day. The above values were modified to accommodate errors and safety factors i.e. to account for
organic constituents other than from domestic
wastewater sources, (e.g. solid wastes, road litter),
solid wastes and other organic constituents from
rainwater runoff.
For BOD, a value of 45
gBOD/per capita per day was used.
As
recommended by the reviewer (Morling, S.) a BOD:
N ratio of 7-8:1 would be usually used in design
practice. Thus, 7.5 gTKN/per capita per day was
also used for further calculations. These values are
multiplied to the estimated population figures to yield
a BOD and TKN daily load in [g/day] for each
manhole subcatchment. These BOD and TKN
production per capita figures were used and assumed
to be valid until year 2025. The BOD and TKN
concentrations in wastewaters in wet weather were
computed as the product of the BOD and TKN
production per day and the dry or wet weather flow
rates.
Qualitative data was collected by EDV catchment
appraisal and was complimented by gathering data
through semi-structured interviews, focused group
discussions and survey.
Data
Data type
Data Source
Supplied
water
volume,
billed
volume and non
revenue
water
volume
20042007
Spreadsheet,
monthly data
per Sampaloc
Business zone
Maynilad
Waters
System
Incorporated,
(MWSI)
Sampaloc
Business
Center
Population
and
number
of
households
per
Barangay 2000
Spreadsheet,
population
figures
per
barangay
Philippine
Census 2000,
Manila
City
Barangay
Bureau
Barangay
boundaries
CAD/
GIS
layer,
referenced
MWSI
Sampaloc
Business zones
boundaries
CAD/
GIS
layer,
referenced
MWSI
and businesses was used to survey a range of amount
willing to be paid by residents across the EDV
catchment. Neumann Optimum function was used
to determine the optimal sample size from a total
household population of 30, 186 of all 85 barangays.
The standard error defined for this sampling is 0.5%.
From a preliminary sample of ten (10) barangays with
five (5) household respondents each, the determined
optimal sample was 972 households for the entire
EDV catchment area. Proportionate sample allocation per barangay was determined such that
depending on the household population of a
barangay, the proportionate numbers of respondents
were surveyed. Unfortunately, only 505 household
respondents from 83 barangays were successful
surveyed out of the optimal 972 households. This
survey’s results introduce more statistical inaccuracies
than planned.
The scenario developed for the questionnaire is the
installation of compact filter-interceptors along major
drainage lines and manholes, to treat influent
wastewaters discharged into the drains by households
and business segments of the catchment and to help
rehabilitate EDV. Some of the surveyed forms were
distributed to local community leaders and the rest
were conducted personally by the author. The survey
was undertaken from August to November 2007.
The survey does not fully address scope of public
acceptability component of this study because of
limited resources. A full perception surveys can be
conducted in the future. Bias and errors introduced
in the WTP survey include:
Willingness to pay survey
The Willingness-to-Pay (WTP) survey is a method of
soliciting the maximum amount the residents of
EDV catchment are willing to pay for a proposed
wastewater treatment infrastructure. This survey also
carried out supplementary questions to estimate a
number of other socio-economic conditions and
opinions related to this thesis.
For the sampling design, a stratified random sampling
method of households (formal and informal houses)
1) Errors from false answers
2) Non binding document and survey of WTP
3) Institutional biases
4) Incomplete and imperfect information
28
Table 3. Input parameters in the model and metadata used in the SWMM model (Balogh 2008)
Data
Data type
Data Source
Conduit profiles and original designs:
Spread sheet, CAD file
JICA Study 2000, from MMDA
Spreadsheet,
population
figures per barangay
JICA Study 2000, from MMDA
Manning’s roughness coefficient
Spreadsheet for drainage
design
Central Manila
Division, MMDA
Time series of rain events
Spreadsheet, hourly rainfall
data
PAGASA- MMDA Rainfall gauging
stations (Aviles and Science
Garden stations); Balogh (2008)
notes
Time series of dry weather flow rates
Spreadsheet, hourly pattern
for each manhole (using
Assumed wastewater production
Cross-section area, diameters, conduit length
surface and invert elevation
Estero de Valencia cross-sections
0, 100, 300, 340, 400, 450, 500, 560, 615
Other limitations
There are substantial study gaps on the wastewater
production and quality in the EDV catchment. Such
arises from the difficulties in collecting information
on water consumption e.g. on illegal connections,
household population etc.
Actual on site
measurement of the wastewater parameters in the
conduits were not available. Also, the effects of solid
wastes on the organic load in the drainage pipes were
lacking. Such can only be considered in the
application of safety factors in the design.
Unfortunately, this research study alone can not
address all the data gaps needed for very detailed
design. The value of this work can be mostly
attributed to the ideas of alternative system it
proposes and designs. This research necessitates
pilot studies for design calibration and testing.
For the hydrological calculations, this research has
adapted approximate the rainfall patterns in the EDV
catchment from available rainfall data from near by
sources, (Aviles Pumping station and Science Garden
rain gauge station) from Balogh (2008) with a model
assuming minimal infiltration.
The catchment
subsurface/groundwater flow dynamics were also
ignored in the design process.
Solid waste constituent characterizations on the study
site were not available in the time of this writing.
Solid wastes contribute to the pollutants’ load in the
drainages and will consequently affect not just the
choice of wastewater treatment system but also of the
biosolids management system.
Most of the designs and recommendations were lifted
from published materials e.g. textbook of Metcalf and
Eddy (2003) and EPA (2000) on existing techniques
and methodologies for various wastewater treatment
systems design.
Thus, the capacities and the
efficiencies discussed and taken herein were not from
independent laboratory experiment but from
published experimental researches, reviews, manufac-
Flood
Control
turer’s information and full scale plant study for
specific unit processes. Most of the given formulas
quoted from other publication were taken as they are,
and were not proven in this Master’s thesis, design
project. It is thus highly recommended to pursue
further experimental investigation to validate this
thesis treatment system designs and findings.
Fig. 18 Snap photo of flow direction and flow
accumulation model for EDV catchment in GIS
software interface
Fig. 19 Drilled Metal plates and different hole
geometries for surface filtration, taken from
Dickenson (1997)
29
Trina Go Listanco
TRITA LWR MASTER
Review of Related Literature
“Holistic technologies” are “schemes that require knowledge,
experience discernment over a given situation” highlighting the
importance of “variant and dynamic” contexts; and more
importantly, as what differentiates it from “prescriptive
technologies”; intends to minimize disaster rather than to
maximize gain. (Franklin 2001)
The first part of this literature review presents an
overview of highly relevant methodologies and
processes published to be effective for achieving the
pre selected constituent removal or reduction. The
second part presents related concepts and
frameworks for selection, management and the
intended benefits of particular treatment systems.
Table 4. According to several sources, typical
concentration values and ranges (in mg/L) for TSS
Strauss et al (1997) and Mara
(1978)
Typical values for tropical countries
(g/m3)
MWSS Typical septic tank analysis
(g/m3)
Metcalf and Eddy (2003) Typical
values in municipal wastewater
(g/m3)
values in combined sewers and
drainage systems
(g/m3)
EDV waters baseline data
(PRRC, 2007)
(g/m3)
Definitions and Concept background
This chapter briefly presents operational definitions
of frequently used concepts, parameters and terms
mentioned in this thesis.
Total Suspended solids (TSS)
Total suspended solids are described “categorically”
as particulate solids that can be filtered out (usually by
Whitglass filter, of 1.28µm) after evaporating a water
sample by 105° Centigrade. (Metcalf and Eddy 2003)
Consequently, different sites at the EDV catchment
have a variety of TSS concentration values.
Biochemical Oxygen Demand (BOD) and Soluble BOD
BOD is the typical parameter used to measure the
amount of biodegradable organic matter in
wastewater. Soluble BOD is the fraction of organic
matter in dissolved form. Because no exact data for
EDV wastewaters for sBOD was available, a fixed
fraction of 0.6 BOD was used for sBOD constituent.
Nitrogen and Phosphorus compounds
Nitrogen, Phosphorus and their compounds are
oftentimes referred to as “nutrients”. But in large
quantities, they create imbalances in water bodies
such that certain organisms thrive and dominate the
ecosystem resulting in “eutrophication”.
Total coliform
Total coliform is one of the most often used
indicators and measured, among many other
pathogenic organisms in wastewaters. In take of
coliform bacteria can lead to gastrointestinal
problems, thus remain to be a major public hazard if
not reduced or removed in waters.
Biosolids
Referred traditionally as “sludge”, is a collective term
for harmful by-product of various biological
processes in wastewater treatment operations,
occurring in a mixture of liquid and solids.
Biofilm
“Biofilm” refers to the thin layer of “slime” that
grows in fixed surfaces capable of assimilating and
degrading substrates in influent wastewaters.
200-700
90-120
120-370
270-550
20
Table 5. Typical values for BOD in wastewaters
according to different sources
(1978)
(g/m3)
3
(g/m )
(g/m3)
drainage systems (g/m3)
EDV baseline data
(PRRC, 2007)
BOD5 (g/m3)
250-1250
150-250
120-380
60-220
40
Table 6. Typical values of N and P constitituents in
wastewaters according to surveyed literature.
30
(1978)
NH4-N (g/m3)
NO2 – N
(g/m3)
TKN (g/m3)
30-70
drainage systems TKN (g/m3 ) and
3
Total P (g/m )
EDV baseline data
(PRRC, 2007)
3
Nitrate-N and Phosphate-P (g/m )
4-17 TKN
1.2-2.8
n/d
20-705
<0.010;
1.38
properties of which, must be able to mechanically
separate at least 20mm of solid particles. The coarse
surface screening handle particles of the size of about
12-50 mm size such as rock debris, branches, leaves,
plastics etc (Metcalf and Eddy, 2003). Such coarse
screens must be rigid enough to handle not just
weight of screenings but additional pressure from
vehicles and possibly pedestrians. Perforated metal
plates or drilled plates are strong filter media which
could be made durable for road inlet straining. (Fi.g.
19). And to reduce flow resistance and clogging,
Dickenson (1997) recommends a conical or “stepped
holes” geometry in a thick plate. Drill metal plates
installed must be regularly maintained and secured.
In dry weather, the inlet metal plates can be fixed
with a woven mesh screen bag, of finer openings hole
as support container that can be emptied of trapped
fine solids and can be reused regularly. (Fig. 21)
The preliminary solids separation for the CSWWTS
in EDV at the road inlet only separates solids from
the roads. Successive screens or filters must also be
installed along the drains, to separate solids in the
conduits from the household pipes connected to the
drains. Tangential flow screening is among other
“fine screens” developed for removal of floatable and
other solids especially for combine sewer overflows.
(Metcalf and Eddy 2003) The technical unit involves
a continuous separation process and without any
moving parts. (Fig. 20) A unit requires small area;
and is suitable for installations inline with the drains.
Such can also be easily maintained. It is composed of
a separation chamber and a cylindrical screen (to
about 1 mm screening) where wastewater or surface
water can pass in a circular motion while deflecting
the solids towards the center. (Metcalf and Eddy,
2003) The solids can then be collected in the bottom
central sump, while the floatables are trapped in the
removable cylindrical chamber screen. (Williams
2000, in Metcalf and Eddy 2003) This kind of
stationary, non powered, fine screen is a manageable
option for an inline installation. The chamber it self
can be adjusted to detain and accommodate a small
fraction of storm water and help alleviate early
discharge. The net effect of such detention chambers
are mentioned in Balogh (2008), as measured by its
“retention efficiency” especially during historic
rainfall records (Bekele et al 1993 in Argue 1995).
Head loss calculation through the fine screens was
provided in Metcalf and Eddy, (2003) and notes that
fine screens should be preceded by coarse screens
especially in combined storm and sanitary collection
systems and especially during the “first flush”.
Other fine screens options e.g. fine screen plates and
rotary drum screens are presented in Metcalf and
Eddy (2003) and is summarized in Table 8 Since
drains are known for accumulating fragments and
bulks of solid wastes and solid particles of all sorts,
e.g. sand, rocks and debris; multiple solids separation
units along the drainage network is integral to the
design to avoid deposition of particles along the
conduits in case of reduced flow rate causing clogged
drains and wearing out of subsequent treatment
installations e.g. RBC’s and “biotowers”.
Table 7. Typical measured values of coliforms from
different literature
(1978)
Helminth eggs (nµm/L)
Total Coliform and Fecal Colifrom
(MPN/100 ml)
Fecal Coliform (MPN/100 ml)
drainage systems Fecal Coliform
(MPN/100 ml)
EDV baseline data
(PRRC, 2007)
Total and Fecal Coliform (MPN/100
ml)
300-2000
6
7
10 -10
5
7
10 - 10
105-106
5
24 x 10
Principles for Solids separation
Solid waste constituents in the wastewater stream,
along the drains and in the estero waterways are to be
addressed foremost in a CSWWTS. The Solid Waste
study reveals the average solid waste production in
the National Capital Region is 0.5 kg per capita per
day, composed mostly, (50%) food and other
organics, (25%) plastics and (12%) paper.16 (ADB
2003) It is important to note that different sectors
and socio-economic groups will produce different
amounts and kinds of solid wastes. The disposal and
management of which is even more difficult an issue
but is integral to the implementation and operation of
an in line wastewater treatment system. The volume
of solid wastes accumulated and disposed from the
Estero de Valencia Pumping Station reached 1035
cubic meters in 2002; and from years 2003 to 2006
has been slowly decreasing from 554 to 725 to 418
and to 360 cubic meters each year. These solid
wastes are not sorted and are typically mixtures of
non-biodegradable materials and organic wastes from
communities along the estero and from sources
upstream. (EDV Pumping Station Report, MMDA
2006)
Screening, which is the physical separation of solids
from the liquid carrier by straining materials larger
than the pore sizes or holes of the screen, is a an
important step to ensure the efficiency of the
subsequent treatment methods. Since the drainage
has a number of solid waste entry points, e.g. road
side inlets, household pipes connected to the
conduits, series of screens must be used along the
drainage lines or surfaces. The materials and
16Waste
Analysis and Characterization Survey
(WACS)
reveals
remaining
solid
waste
characterization: 5% met als, 4% residual, 3% glass
and 1% special/ hazardous waste
31
Trina Go Listanco
TRITA LWR MASTER
Principles for Total Suspended Solids Reduction
Solids separation is crucial to the capacity of an in
line combined storm and wastewater treatment
system and pose the biggest challenge for such a
wastewater treatment system management.
Sedimentation is among the most practical methods
of separating solids from influent wastewater in the
preliminary treatment stage.
This process of
separation of solids mostly relies on differential
densities of particles that if allowed ample time, will
settle naturally because of gravity.
Solid particle settling in a still fluid has “vertical
velocity or settling rate proportional to the particle
density and the square of its diameter, and inversely
proportional to the viscosity of the fluid.”
(Dickenson 1997)
The typical BOD and TSS performance of primary
settling tanks is represented as a function of
detention time, in a graph from Greeley (1938) in
Metcalf and Eddy (2003) following the relationship
that was quoted from Crites and Tchobanoglous
(1998). The functions are hyperbolas dependent on 2
empirical constants at 20 °C. (Fig. 22) The function
presented may have been from most well maintained
settings reflecting only the most optimum
performances. For safer assumptions, a lower BOD
and TSS removal will have to be expected for the
proposed units. The design consideration for setting
up a sedimentation tank considers the influent flow
rates and flow velocity to estimate a maximum depth
and retention time for settling to be optimal apart
from controlling thermal stratification, eddy currents
and wind induced circulation cells. (Metcalf and
Eddy 2003) Particle separation by settling can be
achieved in designed chamber also acting as flow
buffer in dry or wet weather.
A primary
sedimentation tank is an infrastructure that could be
difficult to maintain and monitor if built
underground, but may prove to be useful if
configured and integrated for an “inline” system or
for future upgrading.
Tangential or cylindrical fine screens in chambers can
thus be re adjusted to serve as a basin and surface
filter along the drainage lines. Instead of using just
one fine screen, the chamber can be fitted and sized
Fig. 20 Image of a tangential flow fine screen filter,
downloaded from manufacturer’s website. Figure was
taken from SurfSep’s (manufacturer) website.
to allow settling of solids to a collecting chute, which
could be lined with micro screen bucket to collect
settled solids. The volume of the chamber directly
influences the retention times and thus the TSS
removal capacity. From the graph provided by
Metcalf and Eddy (2003) for settling tanks, influent
wastewaters with TSS concentrations of 100-300
g/m3, can be (optimistically) expected to be reduced,
maximum 40% at a retention time of 0.5 hour.
Micro-screens are very fine surface filters with a
range of 20-35 µm openings. It can, to some degree
collect TSS constituents prior to the RBC’s and
“biotowers”, and collect biosolids after the biological
treatments.
This is possibly achievable if
sedimentation or settling chambers can be introduced
prior to the micro-screen installations. Metcalf and
Eddy (2003) adapted from Tchobanoglous (1998)
“typical design information for micro screens used
for screening secondary settled effluent”.
Apart from surface filtration, depth filtration
methods provide another mechanical filtration that
“employs a medium with a significant amount of
thickness providing filtering depth, such that the path
of flow through the medium is much longer and
random.” Dickenson (1997)
Fig. 21 Images of different
enlarged woven mesh
screens in “twilled square
weave”. Adapted from
Dickenson (1997)
Table 8. Typical Properties of Fine Screen bars and rotary drum screen, Lifted from Metcalf and Eddy (2003)
Fine Screen type
Size of
opening,
mm
Moisture
content, %
Specific weight,
3
kg/m
Volume of screenings
3
L / 1000m
Range
Typical
Fine screen bars
12.5
80 -90
900-1100
44-110
75
Rotary drum screens
6.5
80- 90
900-1100
30-60
45
32
Table 9. “Typical Removal Efficiencies” of Sand filters (Lifted from Cheremisinoff, N. (2002) p. 262)
Pollutant
Percent Removal
Pollutant
Percent Removal
Faecal coliform
76
Total Organic Carbon
(TOC)
48
Biochemical Oxygen
Demand (BOD)
70
Total Nitrogen (TN)
21
TSS
70
Iron, Lead and Zinc
45
“The overall performance of depth-type filter can
be better than purely mechanical action because
direct interception as inertia of particles impinging
on to the filter medium may generate absortive
surface forces.” (Dickenson 1997, p. 31)
In slow granular sand filters, with usually fine sands
and relatively lower hydraulic performance, with an
average filtration velocities range from 2 – 5 meters
per day, thus biochemical processes e.g.
biodegradation may also be facilitated especially in
the early operation stages. (Cheremisinoff 2002).
Depth-type filters with granular media for on site and
inline filtration is apparently viable for parallel and
support installations in the drainages.
The above mentioned mechanisms of filtration or
solids separation are known properties of constructed
wetlands e.g. a reed bed (EPA 2000 and Wood,
1995). The VSB is essentially a subsurface flow
constructed wetland sometimes designed in a
conformed reed bed.
The reed bed is an adapted system mimicking the
matter flows and interaction in a natural wetland
system. The term subsurface flow in both reed bed
and constructed wetland techniques refers to the
discharge of influent wastewater to the reed bed
through the pipes buried in the reed bed. And as in
constructed wetlands “the provision of a suitably
permeable substrate in relation to the hydraulic
loading rate to obviate surface ponding is the most
expensive component of subsurface flow system”
(Crites 1994 in Wood 1995)
The subsurface media, of a design specification,
provides opportunities for flocculation and settling of
suspended solids, primarily through gravity. With
high surface area and very slow flow velocities, VSB
can be used for settling colloidal and supra colloidal
solids with less probability of re-suspension. (EPA
2000)
Reed beds with planted macrophytes or vegetated
submerged reed bed (VSB) may enhance habitat
values, aesthetics and perceived “naturalness” of the
domestic wastewater treatment process (Tanner,
2001) although the role of plant roots in oxygen
transfer and biofilm attachment is still not clear. In
general it was found out that most of most of the
“fraction of the wastewater flow passes below the
root system in VSB facilities and that the role of the
roots in TSS removal has not been proven
experimentally” (EPA 2000) Other significant
functions and applications of small scale VSB in
wastewater treatment systems are reviewed in the
succeeding sections.
Such depth-type media is usually made of
diatomaceous earth, sands, clays, wooden fibers and
cotton fibers. (Dickenson, 1997)
High rate depth filtration is discussed in Metcalf and
Eddy (2003) as one of “advance wastewater
treatments” for potable water treatment, for
supplementary effluent treatment, for conditioning
before disinfection and for membrane filtration pre
treatment. But the principles of slow rate depth
filtration (2-6 L/ m2*min) for small scale installations
is applicable at lower hydraulic loading rates and at
larger filter media surface areas. Unlike, rapid depth
type filtration which needs regular backwashing, slow
rate filters need not be intricately operated. Its top
layer may have to be replaced every few months.
Further, depth filter process can be enhanced by
using sorptive media. Coconut shell carbon, a
material cheaply available in the Philippines, “is one
particular type of activated carbon that has proved a
success in metal recovery, gas purification and
nuclear protection” and can provide cheap source of
sorptive filter media. (Dickenson, 1997)
Slow rate depth type-filtration achieved by VSB’s can
be installed (in multiple sites) as another step to
reduce TSS prior to or parallel to the RBC’s and
“biotowers”, especially in pocket spaces. And since
raw wastewater and storm water contain widely
distributed particle sizes, a “triple–type” bed with
gravel, sand, coconut shell charcoal or soil can be
appropriate for a VSB depth-type filter. The use of
sand in the VSB media, as part of the depth filter, can
be described by principles of slow rate granular
filtration described in Cheremisinoff (2002) as:
“The filter media consists of a bed of granular
particles (typically sand or sand with anthracite or
coal). The anthracite has adsorptive characteristics
and hence can be beneficial in removing some
biological and chemical contaminants in the
wastewater”. (Cheremisinoff 2002, p. 243 )
33
Trina Go Listanco
TRITA LWR MASTER
Principles for Biological Oxygen Demand Reduction
Biological treatment methods and performance are
largely dependent on temperatures. Warmer temperatures are generally conducive to effective rate of
biological processing or degradation. Attached
growth systems for biological treatment use organic
wastewater “sprayed over” and let to percolate over
fixed packing material or high surface area: volume,
filter media. This media is where a microbial slime
layer (biofilm) is allowed to develop on the surface
thus, is also referred to as fixed-film system (Kiely
1997) where mechanisms of mass transfer of
substrate and electron acceptors occur. (Metcalf and
Eddy, 2003) The outer biofilm layer (0.1 – 0.2 mm)
is where organic material from the influent
wastewater can be adsorbed and degraded by aerobic
microorganisms and as water penetrates into the
biofilm, oxygen is consumed and an anaerobic
environment is met. (Metcalf and Eddy 2003) Thus,
controlled BOD removal and nitrification could be
achieved in such fixed spaces and reactors by
providing sufficient hydraulic and organic loading
and air. The biofilm thickness may range from 100
µm to 10 mm (WEF 2000 in Metcalf and Eddy 2003)
Trickling filters were originally used with rock
materials as media, but since the 1950’s plastic
packing capable of high loading rates and taller filters
have been introduced in the U.S. and are called
“biotowers”.
(Metcalf and Eddy 2003)
The
“biotower” can be configured to have a low footprint
but should be assessed further for risks of reported
media cracking. Other advantages of the “biotower”
trickling filters, particularly over the activated-sludge
process are enumerated in Metcalf and Eddy (2003):
Fig. 22 Graph of typical BOD and TSS removal in
primary sedimentation tanks from Greeley (1938) in
Metcalf and Eddy (2003)
basis for rock type CN ““biotowers”” in Metcalf and
Eddy (2003) cited the U.S. EPA (1975) for the
relationship of BOD volumetric loading to
nitrification efficiency, and that:.
“For 90% nitrification efficiency, a BOD loading
of 80 g BOD/m3*d is recommended. At a
loading of 220 g BOD/m3*d, about 50%
nitrification efficiency could be expected.”
(Metcalf and Eddy 2003, p. 923)
The quotation may be true at certain temperatures or
may be most optimum values. It is mentioned further
that a “dissolved oxygen (DO) of 2.8 g/m3 is
required for nitrification without oxygen diffusion
limitations, at a liquid concentration of NH4-N
concentration of 1.0 g/m3.”(Metcalf and Eddy 2003,
p. 924) And so to maximize the nitrification and
NH4 -N removal capabilities of the “biotower”,
another BOD removal treatment stage prior to the
trickling filter process his ideal. Such pre- CN
treatment method can be installed along the upstream
drainage conduits, to “condition” the influent
wastewater load by diluting the BOD concentrations
of primary effluent from upstream sources before
subjecting the wastewaters to the CN treatment in
“biotower”. The estimated BOD removal in plastic
packing was found to be related to the hydraulic
loading application rate, and that BOD remaining
along the depth is a first-order function. (Velz 1948
in Metcalf and Eddy 2003) Thus, multiple
installations and designs of “biotowers” depend
largely on site-specific wastewater flow rates and
influent BOD concentrations along the specific
drainages. “Sloughing” is the dislodging of biofilm
fragments from the filter media surfaces in the course
of the treatment cycles. Such biosolids from the
“biotower” can be handled through surface filtration
and composting. (Discussed in the subsequent
section on “Biosolids”)
“…1) low energy required, 2) simple operation
with no issues of mixed liquor inventory control,
3) no problems of bulking sludge in secondary
clarifiers, 4) better sludge thickening properties, 5)
less equipments maintenance needs and 6) better
recovery from shock loading are among the
advantages of trickling filters over activatedsludge process. “ (Metcalf and Eddy 2003, p. 889)
Gonzales (1996) summarized the factors affecting the
choice of aerobic processes for biological treatment.
(Table 10) And for EDV catchment, the trickling
filter option is apparently among most suitable
treatment process. The “biotower” can be retrofitted
in limited space and could be expanded vertically.
They are also reviewed to be a treatment alternative
which requires moderate skilled personnel and
operation costs. The estimation of BOD removal
performance has been derived by Schulze (1966)
from a first order reaction considering the changes in
BOD concentration in the filter with time; and the
derivation has been applied by Germain (WEF, 2000)
for trickling filters with plastic packing.
The “biotower” is potentially capable of “combined
BOD removal and nitrification” (CN). The design
34
A VSB unit functions as a horizontal fixed-film
bioreactor that mostly takes an anaerobic (anoxic)
metabolic pathway.
(EPA 2000) The vertical
submerged bed is described in Wood (1995) to
“function a bit more than in situ contact chamber and
attached growth biofilter”. The substratum apart
from providing anaerobic or anoxic environment also
“acts as a simple filter for retention of influent
suspended solids and generated microbial solids,
which are then degraded and stabilized over an
extended period within the bed, such that outflow
suspended solids levels are generally limited.” (Wood
1999)
Although the main contribution of plants in a VSB is
still debatable, it is generally accepted that at least
near the immediate zone of plant roots (Brix, 1994)
oxygen could be delivered to the media bed, the rates
of oxygen transfer by macrophytes ranges from 0- 3g
O2 /m2 day. (EPA 2000) But for most parts, the
reed bed remains predominantly anaerobic
environment
where
methanogenesis,
sulfate
reduction and denitrification proceed. (EPA 2000)
Thus, VSB installations function as a TSS filter and a
biological treatment “support” installation before,
parallel or after the biotowers.
Fig. 23 Components of a typical rotating biological
contractor adapted from Kiely (1997)
The estimation for BOD effluent concentration is
thus computed from the assumed secondary clarifier
effluent sBOD/BOD ratio of 0.5. (Metcalf and Eddy
2003) Since sBOD data of influent wastewaters in
EDV drainages is not available, a range of
sBOD/BOD ratio can be assumed from 0.5 to 0.75.
For design assessment purpose, a ratio of
sBOD/BOD of 0.6 was also used. The ratio used for
EDV design is a major assumption entirely based on
the average of the typical provided range of 0.5-0.75.
Since no ratio is available for EDV catchment, on site
measurements are strongly recommended to be
estimated. The sBOD/BOD ratio in wastewaters
during dry and wet weather and along the treatment
process may actually differ.
A computation procedure for RBC BOD removal
process was detailed in Metcalf and Eddy (2003) and
was used for EDV design.
Rotating Biological Contractor is thus a preparatory
treatment in the upstream sites in EDV. Such could
be staged in series, alongside the drainage conduits,
such that area requirement for shafts could be
reduced and the influent BOD loading for each
successive stage could be substantial for the mass
transfer. RBC design information was also
summarized by Metcalf and Eddy (2003) and Cortez
et al (2008) enumerates the important design
parameters for RBC.
A staged rotating biological contractor (RBC) is also a
non submerged, fixed-film biological reactor that is
typically made with high density plastic attached in a
rotating shaft to form a cylinder; and is presented in
Cortes et al (2008) as “unique and superior alternative
for biodegradable matter and nitrogen removal”. The
partially submerged disc of high surface area is made
to rotate in a shaft, and as it comes in contact with
influent wastewater exposes the liquid to air. As it
turns, the liquid trickles, delivering oxygen to the
reactor and providing conditions for aerobic biomass
and nitrification. (Kiely 1997, Metcalf and Eddy
2003)
The RBC has been known as secondary treatment
unit for a variety of applications e.g. nitrification,
denitrification and phosphorus removal in landfills
leachate, food industries, pulp and paper industries
etc. (Cortes et al 2008)
The RBC design criteria provided by Metcalf and
Eddy (2003) on BRC units for BOD removal quoted
a second-order model by Opatken (U.S. EPA 1985)
further developed by Grady et al (1999) which yielded
the estimation function for soluble BOD (sBOD)
concentration at each successive RBC disc.
Sn =
Principles for Nitrification and NH4-N Removal
Designing a fixed-film trickling system for
“combined BOD removal and nitrification
treatment” was lifted from Metcalf and Eddy (2003).
Okey and Albertson (WEF 2000) in Metcalf and
Eddy 2003) have “found a linear relationship between
the specific nitrification rate and the influent
BOD/TKN ratio for combined systems”. And that
“the amount of nitrification can be estimated by
using the volumetric oxidation rate (VOR) defined by
Daigger et al (1994).
− 1 + 1 + (4)(0.00974( As / Q) S n −1
(2)(0.00974)( As / Q)
Where:
S n = sBOD concentration in stage n (g/ m3)
As = disk surface area n (m2)
Q = flowrate (m3/day)
35
Trina Go Listanco
TRITA LWR MASTER
Table 10. Summary of comparison of 3 aerobic biological treatment systems, lifted from Rich (1980) in Gonzalez (1996)
OPERATING CHARACTERISTICS
System
Resistance to shock
organics or toxics
Lagoons
Trickling filters
Activated
(sludge)
loads
of Sensitivity to intermittent Degree of skill needed
operations
Maximum
Minimum
Minimum
Moderate
Moderate
Moderate
Minimum
Maximum
Maximum
Land needed
Initial costs
Operating costs
Maximum
Minimum
Minimum
Moderate
Moderate
Moderate
Minimum
Maximum
Maximum
COST CONSIDERATIONS
System
Lagoons
Trickling filters
Activated
(sludge)
It is important to note also that according to Okey
and Albertson (WEF, 2000), the DO concentration
affects the nitrification rates more than the
temperature and that a bulk liquid dissolved (DO)
concentration of “2.8 mg/L is required for
nitrification without oxygen diffusion limitations, at a
liquid NH4–N concentration of 1.0 mg/L.” (Metcalf
and Eddy 2003, p. 924)
Airflow in “biotowers” is essential for the efficacy of
operations.
Natural draft, powered by the
temperature gradient between ambient air and the air
inside the “biotower”, has been traditionally used.
Draft or the “pressure head resulting from the
temperature and moisture differences can be
determined from the equation provided by Schroeder
and Tchobanoglous (1976) in Metcalf and Eddy,
(2003). In Manila where temperature differentials
could be small, air flow by natural draft may not be
sufficient.
Maintenance and operation of
“biotowers” would have been much more convenient
and simple if air delivery by natural draft could be
relied on.
A study by Dow Chemical during the development of
plastic packing provided a quantification of required
oxygen supply for a combined BOD removal and
nitrification tower. (Metcalf and Eddy 2003) The
calculation for total airflow requirement is also
provided with the air temperature and pressure
correction because for each degree above 20 °C, the
airflow rate increases by 1%. Manila sewage has
typical temperature of 27.9 °C, and atmospheric
temperatures can often, if not always be higher than
20°C, the temperature correction equation provided
in Metcalf and Eddy (2003) was used.
The measures and “needs” have been enumerated by
Metcalf and Eddy (2003) for the design of a
“biotower” using natural draft; e.g. “underdrains that
should not be more than half full; ventilating access
ports at the central and ends of the collection
channel; vent stacks in the peripheries of the filter;
open area of the slots in the top of the underdrain
blocks (at least 15% of filter area); and open grating
of 1 m2 in ventilating manholes for every 23 m2 of
filter area.” Information on natural drafts possible in
the EDV catchment sites have not been investigated
in detail at the time of this thesis’ writing. It is noted
that airflow dynamics in the proposed system is
crucial to airflow design of the system, but design for
supplemental air delivery is provided, and is thus
another limitation of this thesis.
Further, Metcalf and Eddy (2003) provided and
summarized process design criteria for a combined
BOD and nitrification “biotower” and stressed that
the “major impacts on nitrification performance are
the influent BOD concentration and dissolved
oxygen concentration within the trickling filter bulk
liquid.” Metcalf and eddy (2003), p923
Referenced studies for nitrification design were also
summarized in Metcalf and Eddy (2003) p.923 as
follows:
“Nitrification 1) could occur at a maximum rate at
soluble BOD (sBOD) concentrations below 5
mg/L, 2) was inhibited in proportion to the
sBOD concentration above 5 mg/L, and 3) was
insignificant, in proportion to the sBOD
concentration of 30 mg/L or more.” Harremoes
(1982)
“A steady inhibition of nitrification rates occurred
as the sBOD concentration was increased from
1.0 to 8.0 mg/L.” Huang and Hopson (1974)
36
Fig.
24
“Typical”
Vegetated Submerged Bed
(VSB) Lifted from EPA,
(2000)
“Nitrification rates in fixed film processes are
inhibited at BOD concentrations above 10
mg/L.” (Figueroa and Silverstein 1991)
Constructed wetlands as in VSB’s have popularly
represented low-cost alternative to wastewater
treatment to expensive energy intensive treatment
technologies as they provide filter media,
sedimentation spaces, adsorptive spaces for solids
separation and bio-geo-chemical transformations.
However, wetlands systems come not without
problems and challenges. Among issues like nutrient
removal, ecological protection, space requirements
and
disinfection
capabilities;
maintenance,
sustainability and capacities of such technology are
continually being questioned. Brix et al (2001) notes
that on site solutions e.g. compact bio-film systems,
sand filters and constructed reed beds “are able to
fulfill standards for suspended solids, BOD removal
and nitrification but P removal remains to be a
problem”. Nutrient removal in constructed wetlands
is rather complex to model; and the role of
macrophytes in nutrient removal can not be reduced
to just nutrient uptake. (EPA 2000, Tanner 2001) In
a study by Dolan et al (1981) mentioned in DeBusk et
al (2001) on a highly loaded treatment marsh plots in
Florida it was found that “69.2% of the loaded P was
stored in the soil complex, 23.2% in below-ground
biomass and 5.2% in above-ground biomass”. This
highlights the significant effect of substrate media for
long term phosphorus removal. Further, phosphorus
removing capacity of substrate media was found to
depend largely on the mineral content i.e. Calcium
(Ca), Aluminum (Al) , Iron (Fe) that can adsorb and
bind phosphorus, Brix et al (2001) especially when
Netter (1992) in Brix et al (2001) found that P
removal in constructed reed beds with ferruginous
sand was efficient.
“The nitrification efficiency for both rock and
plastic packing was similar at similar BOD surface
loading rates (g BOD/ m2*d); and that a surface
loading rate as low as 2.4 g BOD/m2*d is
necessary for more than or equal to 90 % NH4-N
removal.” (Parker and Richards 1986)
“The oxidation of BOD and NH4-N in trickling
filters with plastic packing could be characterized
by a volumetric oxidation rate:” (Daigger et al
1994)
It is therefore necessary for the overall process design
in upstream installations to substantially reduce BOD
through attached growth treatment, (RBC) prior to
introducing the effluent wastewaters to the
“combined BOD removal and nitrification
biotower”. This component of the treatment system
shall be installed close to the outfalls, to maximize
and complete treatment procedure where space could
be less difficult to acquire and negotiate for. RBC
units are reported to be capable of nitrification as
well, but nitrification is generally achieved only after a
minimum of 4 stages. (Cortez et al 2008) In an inline
setup, 4 RBC stages can occupy longer roads and
could mean intercepting another manhole. RBC
nitrification stages remain one possible option for
installation instead of the “biotower”. This option is
not further assessed in this thesis, but is
recommended to be tested and compared on site.
Principles for Phosphorus Reduction
Phosphorus in form of phosphate in Estero de
Valencia and all other esteros profiled in March 2007
exceeded the maximum allowed limit for Class C
waters. (PRRC 2007) This necessitates P removal in
the estero waters or in the influent waters to the
esteros.
“P chemistry in natural and constructed wetlands
is controlled by organic P pool and the
iron/aluminum bound fraction.” (Gale et al 1994
in DeBusk 2001, p. 42)
Ciupa (1996) in Brix et al (2001) noted that uptake of
P is initially high but decreases over time as the Psorption capacity of the sand media is being used up.
37
Trina Go Listanco
TRITA LWR MASTER
commercially valuable emergent macrophyte
(Pontedaria Cordata, L.) a sustainable means of P
removal”. From an influent wastewater with 1.7 mg
P/L and hydraulic retention rate (HLR) of 42cm/day,
a removal rate of 7 g P per year was projected.
(DeBusk et al 1995 and DeBusk et al 2001) VSB’s can
be installed in small plot gardens in upstream
communities or household clusters, along roadside
the drainage canals, along street corners or along the
estero. Variations and details of VSB installations
will be presented in the Results and Discussion
chapter. The application of VSB treatment for the
informal settlements along EDV has to be assessed
further.
For P removal, Brix et al (2001) observed that Ca
content of media is important, while Al and Fe
content are less important since precipitations of
calcium phosphates are the main processes
responsible for the removal of P in their study. Brix
et al (2001) also found out that grain size distribution
of media for subsurface flow constructed reed beds is
important criterion for selection, and recommends
Danish EPA (1999), the effective grain size of d10
should be in the range of 0.3 to 2.0 mm, d60 between
0.5 to 8.0 mm and uniformity coefficient d60/d10
should be less than four in order to secure hydraulic
conductivity and to minimize risk of clogging.
Although plant nutrient uptake and storage (e.g. N
and P) have been measured to be a small fraction of
the improved performance of the planted system, and
that the amount of oxygen released through plant
roots were found to be limited to immediate
environment according to Brix (1994); Tanner (2001)
summarizes and highlights the indirect complex roles
and function plants play in a treatment wetland
treatment system:
Principles for Total Coliforms Reduction
Pathogens carried by TSS and exposed to biofilms
treatment systems are made to compete in conditions
(with a degree of sunlight UV irradiation) where they
are not likely to survive. In VSB’s pathogen removal
is found to be connected with TSS removal and
hydraulic retention times. (Gearheart et al 1999,
Gersberg et al 1989 in EPA 2000) In EPA (2000) it
was quoted that Gersberg et al. (1989) “found a two
log reduction in total coliforms is a VSB system
treating primary effluent.” Gravel bed hydroponics
constructed wetlands are also known to remove
pathogens by “mechanisms of adsorption,
sedimentation, filtration, predation and inactivation
due to environmental stress.” (Gersberg et al 1989 in
Williams et al 1995) In the study of Williams et al
(1995) it was found out that the primary removal
mechanism for BOD in biofilm systems is
adsorption, which is also important for pathogen
removal more than sedimentation.
They also
suggested that with the higher temperature (i.e. >27
degrees centigrade in Eygpt field experiment) BOD
treatment and pathogen removal are improved; and
that anaerobic conditions prolong the survival of
faecal coliform in natural waters (Gray 1989 in
Williams et al 1995) and should be avoided.
On site installations of small community VSB can
thus only provide support treatment for other
components of entire treatment system. Their effects
on primary effluents in the drains could include
degrees of BOD reduction, minimal nitrification,
phosphorus removal and pathogen reduction. The
VSB although can not treat all influent wastewaters in
the EDV because of limited sizing, presents a low
cost alternative for distributed and small installations.
Produced biosolids e.g. sloughed biofilms in
“biotowers” and RBC shafts could be handled
systematically within the EDV catchment before
disposal or reuse.
“Wetland plants generally provide low
improvements in BOD and COD removal, and
disinfection.
The primarily affect treatment
performance through ecosystem engineering,
enhancing key nutrient transformation processes
(e.g. nitrification and denitrification) by root-zone
oxygen release and supply of organic matter.”
(Tanner, 2001, p. 15)
Wood (1995) claimed that plants also help “control
odour and nuisance insects (e.g. mosquitoes and
gnats) as they act as biofilter and over-shades in open
water, making it possible for such treatment systems
to be installed close to the communities they serve”.
Macrophyte Based Systems (MBS) for wastewater
treatment is another low cost alternative that rely on
plant assimilation of nutrients and plant harvesting to
reduce nutrients in influent wastewater streams.
“Most studies demonstrated that the floating water
hyacinth was the most productive aquatic species
(Reddy et al 1983, Reddy and DeBusk 1985), capable
of sustained biomass production rates of 42g dry
weight/ m2 day, P assimilation rates of 135 g P/ m2
year, under optimum conditions.” (DeBusk et al 2001,
p. 41) Thullen et al (2005) suggests establishing
“hammocks” or “shallow plant beds” within the
wetland as part of vegetation management to enhance
treatment function in surface-flow constructed
wetlands. Such could be adapted in the EDV
waterways to achieve treatment polishing.
Hammocks can be made to hold and anchor floating
macrophytes in EDV, to avoid clogging of flood
pumps. Although introducing floating macrophytes
can decrease the effect of sunlight in killing
pathogens in flowing waters, the amount of floating
“hammocks” must also be limited and determined.
One of several mesocosm studies in Lake
Okeechobee, Florida found “culturing and harvesting
Discussion on relevant Biosolids Management
“Biosolids” (historically known as sewage sludge) are
the solid organic matter produced from private or
community wastewater treatment processes that can
be beneficially used, especially as a soil amendment.
They contain 93-99 % water and as well as solids and
dissolved substances present in the wastewater
treatment or added during wastewater or biosolids
38
treatment processes” (EPA 1999 p. 13). Biosolids
management is integral to the entire treatment
system. This thesis briefly discusses a potential way
for biosolids management for the proposed
Biosolids characterization depends mostly on the
wastewater composition, the wastewater treatment
and the subsequent biosolids treatment methods
used. EPA (1999) and can vary seasonally along with
wastewater characteristics etc.
Biosolids with
significantly reduced pollutants, become more viable
for composting. (EPA 1999) Biosolids expected
from RBC units and their screenings and the slough
produced by the “biotowers,” compose the bulk of
the biosolids to be handled by the EDV wastewater
treatment system. Although composting as a way for
biolsolids treatment is one option, further
assessments on expected performance must be done.
This thesis presents it as one possible alternative that
can be adapted by communities in support of the
wastewater treatment system.
In the U.S. biosolids that passed certain requirement
e.g. pathogen reduction, vector attraction reduction,
and metal content are allowed for composting. (EPA
1999) Stabilization refers to processes to reduce
pathogens, volatile solids, and odor. The screenings
from preliminary filtrations, pre and post bio
treatment solids can vary in sizes and constituents.
The handling of screenings for the EDV catchment
shall include further segregation before any kind of
disposal. Since Metro Manila typically disposes
municipal solid wastes in landfills, bulky screenings
e.g. non biodegradable solid wastes can be taken to
landfill sites. The finer screenings can be made to be
handled in the composting facility to be established in
each Barangay’s “Materials Recovery Facility”
(MRF)17 as described in the Ecological Solid Waste
Management Act of 2000 and:
biosolids with bulking agent and the “decomposition
of organic matter by microorganisms in a controlled
environment with temperatures as typically 55-60
°C.” (EPA 1999) The bulking agent may be derived
from municipal solid wastes (MSW) and divert them
from getting dumped in landfills. “The high organic
matter content and low nitrogen content common in
compost biosolds is comparable to wetland soils
which provides strong organic substrate, prevents
nitrogen overloading, adsorbs ammonium.” (Peot
1998 in EPA document, undated) Raw and digested
solids can possibly be composted but both will
require some degree of stabilization. Carbon and
nitrogen ratio of 25-35: 1 will provide needed
balance. (EPA document, undated) “Composting
reduces bacterial and viral pathogens to nondetectable levels if the temperature of the compost is
maintained at greater than 55 °C for 15 days or more.
Additionally, it has been demonstrated that viruses
and helminthes ova do not regrow after thermal
inactivation.” (Hay 1996 in EPA undated)
Composting as a “biosolids” management method
has been widely accepted for reasons enumerated in
EPA document18 because of limited landfill spaces,
beneficial reuse in local, federal and state levels, easy
to handle and store and also because of the following:
1) Proven method for pathogen reduction and
production of valuable product
2) Compost soils can suppress disease and ward off
pest
3) Some municipalities, compost is used to filter
storm runoff to remove hazardous chemicals
4) Aside from good soil conditioners, compost
products can be used in mulching for erosion control,
silviculture crop establishment,
5) Compost soils can degrade and alter other
pollutants, e.g. wood preservatives, solvent, heavy
metals, petroleum products
“For this purpose, the barangay or cluster of
barangays shall allocate a certain parcel of land for
the MRF. The MRF shall receive mixed waste for
final sorting, segregation, composting, and
recycling. The resulting residual wastes shall be
transferred to a long term storage or disposal
facility or sanitary landfill.” Section 32, Article 4
of the R.A. 9003
“Additionally, biosolid compost is often used for
soil blending, landfill cover, application to golf
courses, mine reclamation, degradation of toxics,
pollution prevention, erosion control, and
wetlands restoration. It also is used for
agricultural purposes, such as application to citrus
crops. Composts made from biosolids can also be
tailored to remediate contaminated soils.”
(BioCycle 1997, U.S. EPA 1997a and U.S. EPA
1998a in EPA 1999, p. 19)
To achieve a composting facility with integrated
biolsolids management from the wastewater
treatment system, capacity building of communities is
crucial. It is especially true in implementing solid
wastes management, that “things are easier said than
done”. This thesis, although primarily concerned
with wastewater treatment system design, calls for
more research on appropriate biosolids management.
Composting biosolids involves mixing dewatered
Table 11 Summarizes and describes the benefits of
using composted biosolids. It is projected that due to
18 U.S. EPA publication, “Biosolids Technology Fact
sheet, Use of Composting for Biosolids Management
http://www.epa.gov/owm/mtb/combioman.pdf.
Accessed January 2008
Defined in Section 32 of the Republic Act 9003,
”Ecological Waste Management Act”
17
39
Trina Go Listanco
TRITA LWR MASTER
meeting the minimum pathogen and vector
attraction reduction.” (EPA 1999 p. 17)
the beneficial uses of composted biosolids,
technological remediation and efforts to educate
public, EPA (1999) estimated a total increase of
beneficial composted solids use from 60% in 1998 to
70% in year 2010. (EPA 1999)
Butler et al in PWEA document19 found out from
bench and full scale studies on 21 Class B biosolid
producing plants that “minimal lime dosages, coupled
with highly effective mixing can eliminate or delay
production of offensive odor compounds.” (Butler et
al, p.1) Advanced alkaline stabilization methods have
also emerged and are available but are mostly
propriety technologies. (EPA 1999) For EDV
applications, traditional liming with CaO or other
alkaline materials e.g. fly-ash, coupled with effective
mixing, could be more economically viable. But
because reports of adverse effects of liming to soil
acidity and leaching, use of lime as stabilizing and
bulking agent must be assessed further. This topic is
not pursued further in this thesis.
Anaerobic digestion for biosolid stabilization involves
the biological degradation of organic portion of the
biosolids and production of carbon dioxide, methane
and ammonia by anaerobic microorganisms in a
closed tank. (EPA 1999) At bigger digestion scales,
methane gas could be recovered and potentially
power drying and mixing processes. “Anaerobic
digestion is typically operated at about 35 °C (95 °F),
but also can be operated at higher temperatures
(greater than 55 °C [131 °F]) to further reduce solids
and pathogen content of the stabilized biosolids.”
(EPA 1999 p.17) Although liquid biosolids can also
be done for land application e.g. soil injection or
surface incorporation, dewatering is necessary prior
to composting or incineration treatments. (EPA
1999)
Gravity thickening is most common practice prior to
dewatering. (Walker 1998 in EPA 1999) Air drying is
typical method for 40-90% liquid reduction in
biosolids. The process uses sand beds where
biosolids are laid and let to dry by evaporation and
drainage. For EDV wastewater treatment system,
solid waste screenings from road inlets and coarse
screens can be air dried first before disposing to
landfill.
Fine screenings, before and after the RBC units e.g.
sands and silts and sloughed biofilm from shafts, can
also be dried and dewatered by air drying. These
screenings can be processed together with the
screenings from the “biotowers”.
Biosolids containing more offensive constituents and
can be dewatered through combinations of filter
cloths and presses and air drying. For rainy season,
acquisition of centrifuges may be necessary.
Table 11. Benefits and applications of composted
biosolids, adapted from Garland et al (1995) in EPA
(1999)
The are a number of issues arising from adapting
composting for biosolids management, among which
are generation of malodors, survival of primary
pathogenic organisms, generation of secondary
pathogenic bacteria, and lack of consistency in
producing stabilized quality product. (EPA
document, undated) The establishment of such
composting facility in the barangays of EDV should
be assessed further.
Among kinds of composting facility, an aerated static
pile provides low cost, easy to operate, but labor
intensive option for EDV wastewater treatment
system. (Fig. 25)
Small communities or community clusters can adapt a
small scale operation of such aerated static pile
compost which could be handle biodegradable
domestic solid wastes and at the same time, biosolids
produced in the biofilm system installations in EDV
wastewater treatment system. Alkaline stabilization
results in decreased biological action and thus, odor
in the mixture, by the elevation of pH to 12 for about
2 hours (EPA 1999) and is described:
“Alkaline stabilization is the addition of either
quicklime (CaO) or hydrated lime (CA[OH]2),
which is added to either liquid biosolids before
dewatering or dewatered biosolids in a contained
mechanical mixer. Traditional lime stabilization
processes are capable of producing biosolids
19 Butler et al report for Pennsylvania Water
Environment Association (PWEA) publication
document
available
at
http://www.pwea.org/documents/Ext%20Abst_Ho
ward%20Butler.pdf last accessed on January 2008
40
Table 12 Different mechanical dewatering systems used in biosolids management
System
Description
Achieved
solids content
Vacuum filter
Reported to be not in use anymore, the model involves rotating a
drum submerged in a vat of biosolids and applying a vacuum from
within the drum, drawing water into the drum, and leaving the solids
or “filter cake” on the outer drum filter medium
12-32 %
Centrifuges
spin biosolids in a horizontal, cylindrical vessel at high speeds, with
the solids concentrating on the outside of the vessel
25-35%
Belt-filter presses
Work by exerting pressure on biosolids placed between two filter
elts, which are passed through a series of rollers. The pressure
forces water out of the biosolids, and the dried biosolids cake is
retained on the filter belt
20-32%
Plate and
presses
Work by squeezing the biosolids between two porous plates or
Diaphragms. The pressure forces water out of the biosolids, and
the dried biosolids cake is retained on the plates.
35-45%
frame
Dewatered biosolids could then be stabilized by
addition of alkaline materials or by anaerobic
digestion prior to composting. Note that the detailed
assessment of needed biosolids management is
beyond the scope of this thesis.
Currently, final dumping of stabilized and digested
“biosolids” in Lahar fields of Pampanga, is an
accepted practice of MWCI for their STP and SpTP
operations. Although, no reviews on the effects and
other possible applications are available in the time of
this writing, further studies are called for by the
biosolids to these barren Lahar fields presents itself
author. For EDV, the final disposal of stabilized as
another option.
Fig. 25 Aerated static pile adapted from Hickman (1999) in EPA Fact Sheet
41
Trina Go Listanco
TRITA LWR MASTER
for the public or at least the local communities is
necessary. Academic institutions and their research
and extension work can be tapped and focused on
the goals of IUWM or EDV wastewater treatment
system.
The combined storm and wastewater system equally
addresses the problem of untreated runoff during
rain events, with out compensating the need to
effectively drain the city of storm waters. Ellis (1995)
defines “sustainable storm drainage management in
urban catchments intended not only to achieve
effective and safe conveyance of floodwater and
pollution control but also to provide self-supporting
ecological and aesthetic benefits.” He also
emphasized that a “successful integrated approaches
to the management of river corridor requirements in
urban catchments therefore demand not only the
implementation of sound and sustainable ecotechnology but also appropriate institutional
cooperation and local planning.”
Estero de Valencia catchment provides a good setting
to establish integrated storm and domestic
wastewater treatment system with its natural and built
environment assets and properties e.g. several low
lying basins, relatively homogenous land uses.
However, institutional capacities and coordination of
local government and State agencies and the private
utilities company will have to be strengthened.
Gardiner (1994) in Ellis (1995) stressed that the
integrated and realistic approach to urban catchment
planning is a function of water use management
programmes, catchment management plans and local
authority development plans.
The study site is primarily a residential area where
community plans can be made to adapt principles of
“natural engineering”--- a system where runoff
system can be integrated into the site landscaping or
into “blue-green” developments using permanent
lakes, aquatic vegetation and unit cluster techniques.
(Ellis 1995)
The decentralized combined storm and wastewater
treatment system apart from addressing flooding and
pollution issues, provide possibilities of wastewater
reuse and resource recovery, community political
participation according to WTP and improvements in
local environmental health conditions. Parkinson and
Tayler in World Bank 2003 cited an example where
night soil treatment plants in Japan have substituted
piped sewerage system, and thus encourages
adaptation of “intermediate solutions between on site
treatment and piped system” in high density urban
areas” (World Bank, PEM, 2003)
Several literatures highlight the need for improved
sanitation coupled with improvements in water
supply delivery. Noll (et al) in a study of water and
sanitation systems in eight developing countries
found that improved wastewater and sanitation
policies significantly improved the health and body
weight of children, especially in urban areas, and that
improvements in the quality of delivered water im-
Review on Management and Public Acceptability of
Wastewater infrastructures
The operational definition of “appropriate
technology” is defined by a treatment system that is
1) affordable, 2) operable and 3) reliable. (EPA 2000)
The ideals of decentralized wastewater treatment
system have also been adapted in foresights of
sustainable residential development in tropical urban
areas like Singapore. Lim et al (2002) in their paper
on decentralized grey wastewater treatment system in
Singapore public housing explored how water
infrastructure systems could be integrated into urban
housing architecture to create decentralized
wastewater treatment systems that is a core element
of the overall waterscape of the area.
Such
decentralized, underground and on site wastewater
treatment system which also features constructed
ponds and wetlands, may have been ideal for the
development of EDV communities.
The adaptation of such system e.g. for “urban
renewal projects” remains an option for the future
but requires intense assessment and financing
especially for private properties.
Ujang and Buckley in 2002 presented and proposed
the realities and strategies for water and wastewater
management in developing countries. Some of the
key strategic points mentioned were the adaptation of
an “Integrated Urban Water Management” (IUWM).
IUWM as quoted from Ujang and Buckley 2002
“implies an integrated approach in planning and
implementing all water-related urban activities and
components, including water and wastewater
management, solid and hazardous waste, economic
and social factors, as well as community and
governance.
Odendaal (2000) in Ujang and Buckley (2002)
considers the “urban environment, as ideal platform
for pioneering integrated water management”. EDV
drainages provide a “public space” where public and
private sectors can take stock in for an integrated
water management scheme.
Ujang and Buckley (2002) also referred to a strategy
where available technologies in “package forms” that
developed without the progression from a general
public understanding of the environmental issues.
Such are made to be instantly adapted into
technocratic development agenda that is sometimes
labeled “technology leap.”
Appropriate technology is meant to consider not just
the suitability and reliability of the proposed
technologies, but emphasize the process of involving
people through consultations and assessments of
their valuations and cognition of any “technological
solutions”.
The question of ownership and acceptability of
introduced technological development has been
identified as crucial element of developmental works.
Further, while an “appropriate technology” is being
developed and planned, a parallel education campaign
42
proved health only if accompanied by improvements
in sanitation. (Noll et al )
Yearly, the MMDA de-clog manholes and scrape
clean roadside canals and culverts and dredge Estero
de Valencia. DPWH also began an intensive flood
control program with more than 200 maintenance
personnel to pursue the Bantay Estero program to
ensure the cleanliness of 16 critical esteros in Metro
Manila. (DPWH website)
Bantay Estero program attempted to involve estero
dwellers integral into a community based, labor
intensive approach in maintaining the estero
environment. Now, bulk of the work has been
relegated to the MMDA. The Bantay Estero Project
did not really effectively changed ideas and
conditions in the esteros because it lacked the
systemic involvement of the entire catchment’s
stakeholders in maintaining and protecting drainage
systems, including the estero itself. There remains to
be a lack of regard in the fundamental issue of
sanitation system in the area.
1) to understand and communicate community impacts of any proposed infrastructural investments,
2) to solicit perceptions of the people about public
waste water treatment infrastructure, including their
needs or economic/ effective demands20,
3) to propose a range of options for future
wastewater treatment system investments and 4) to
plan pricing systems. The term “demand” has
different meanings to different people three
definitions were presented:
“Felt needs” are reflective of the communities
aspirations that could be driven political and
economic issues.
Engineers particularly are
drawn
to
measure
“consumption”
as
manifestation of demands. The third definition is
the most meaningful definition that was lifted
from White (1997) and Pearce (1991). “Effective
demand” is defined as “demands for goods and
services which is backed up with the resources to
pay for it”. (Webster 1999 in Woodwedge 2003)
“The pollution issue raises a problem of
institutional design: how can government commit
to a long-term pollution policy that reduces the
harms from pollution while avoiding overzealous
pursuit of environmental policy that indirectly
expropriates the investments of the water utility?
“The economist's stock solution for this problem
is to impose a tax on pollution (Polluters Pay
Principle) that fully reflects the marginal cost of
pollution on others. Taxes create a financial
penalty for water pollution, and so provide a
financial reason to invest in either sewers or water
treatment facilities.” (Noll et al)
The contingency valuation survey section of this
study assessed the “demands” of the catchment
stakeholders according to the three abovementioned
definitions and their interactions. The “felt needs”
for wastewater treatment facilities to help rehabilitate
the Estero de Valencia, is an important factor
assessed in this study to establish a backdrop of
environmental values and prioritizations amid the low
and irregularities of income realities of the residents
and respondents.
The current averaged
“consumption based demand” was derived from the
audited values of 2004-2007 billed and non-revenue
water supplied by the MWSI. Lastly, “economic /
effective demand” was obtained through the elicited
maximum contribution or fees willing to be paid or
willingness-to-pay (WTP)21.
Investment planning process is a complex series of
assessments and planning. It commences in needs
and services assessments and technical designing
allows planners to assess peoples’ willingness to pay
for service options and “provides the necessary basis
for projecting sales and revenue”. (Wedgewood and
Samson 2003 publication) More importantly, the
information from CVM is “essential to support
community participation and enable ‘informed
choice’ at the household level as well as for the
community as a whole.”
(WSP 2002)
The
Contingency Valuation Method (CVM) is used:
20 Effective demand is term defined by White (1997)
and Pearce (1981), as “demand for goods which
backed up with resources to pay for ” in Wedgewood
and Samson, 2003 publication.
21 WTP is the maximum amount that an individual
states they are willing to pay for a good or service
(DFID, 1999)
43
Trina Go Listanco
R E S U LT S
AND
TRITA LWR MASTER
period rain fall for until 2016 and 2025. These data
were used as input to SWMM module of the designed
dimensions of the existing profiled conduits and
drainage laterals in EDV. And these data are all
summarized in the maps below. (See also
Methodology, Flow rate estimation)
The
estimation of dry weather and wet weather flow rates
are also discussed; and more in detail in Balogh
(2008). The results are reflected in GIS maps.
(Figures 26 and 27)
DISCUSSIONS
This chapter presents the estimated flow rates,
concentrations and loads for each EDV manhole
subcathment.
Selected manholes for treatment
installations are enumerated and selected treatment
processes and sequence are discussed. Designs are
detailed in figures and the theoretical performance
according to some published models is also
presented.
Treatment Goals
The goals set for the proposed EDV wastewater
treatment system is provided by Philippine law
through the requirements of DAO 35 series of 1990:
“Revised Effluent Regulations of 1990” for all
municipal wastewater effluents discharged to
different “classes of waters”. The DAO 34 series of
1990 provides definition and water quality criteria for
the “classes of water”. And it is good to reflect at
this point, how esteros like Estero de Valencia should
be operationally classified in the first place. Different
set of standards exist for “Coastal” and “Inland
Waters” receiving waters. Esteros are naturally are
somewhere in between those classes. They are
narrow marshes/ creeks that are not protected, thus
not Class SC22 but possibly Class SD23; and they are
inland waters but not used for recreational purposes
and agriculture. By definition according to current
use and conditions, esteros are closest to “Inland
waters Class D”24, since tidal flows are controlled by
the pumping station although its waters are not used
at all. The proposed treatment design takes the
highest of 3 set of standards, and takes EDV as
“Inland Waters Class C”.
Setting the effluent standards dictates the practical
and realistic goals for treatment system. Comparing
other countries’ standards generally gives ideas on
how Philippines water policy fair with other
established practices abroad and gives insight on how
ready the economy and society is for “standard
driven sustainability”.
Five wastewater constituent parameters were
originally selected to be removed i.e Total suspended
solids (TSS), Biological Oxygen Demand (BOD),
Phosphorus (P), Nitrogen (N) and Total Coliforms.
Estimation of “Average Rain event for 2016 and
2025”
Storm water flow rates are based on interpolated
monthly rain distribution from the 4-year data base.
Available hourly rainfall data from year 2003-2006
was collected from MMDA-PAGASA rain gauge
station nearest the EDV catchment, “Science Garden
Station.” Another available hourly rainfall data
source (year 2006) is from the adjacent pumping
station, “Aviles Pumping Station”. From the Aviles
2006 rainfall data, the maximum and average rainfall
event-curve of 2006 was derived. The average and
maximum rainfall curves have been projected using
the Log-Pearson Type III distribution (Chow et al.
1988) for year 2025. The result yielded the maximum
intensity rain that can be expected to occur until 2025
(inclusive of 2016).
Using the projected peak
intensities for 2025, the “design rain event” has been
created and was used as an input to the SWMM. The
“design rain event” is such a rain event which occurs
once between 2006 and 2025. The design rain event
has been calculated using the formula from Chow et
al, (1988, p. 392) in the notes of Balogh (2008). The
following characteristics of average rain are defined
by Balogh (2008). Such was adapted for design of
proposed unit operations.
Estimation of Dry weather flow rates and Wet
weather flow rates for 2016 and 2025
The wastewater production or the average dry
weather flow is estimated to be a fraction of the
supplied volume (by the MWSI utilities and water
supply data) to all barangays in the catchments.
(Calculation methods and assumptions are presented
in Methodology) On the average, the estimated
wastewater produced (inclusive of “NRW”) for the
entire EDV catchment in 222 m3/ day; with a range
of 90- 300 L/ day. The differences in the water
consumption and wastewater production in each
Barangay reflects different conditions of water
supply, wastewater characteristics and concentrations.
The variation can be seen in Appendix I
Class SC: Coastal/ Marine waters, Recreational
Water Class II (e.g. boating); Fishery Water Class II
(commercial and sustenance fishing); marshy and/or
mangrove areas declared as fish and wildlife
sanctuaries
23 Class SD: Coastal/ Marine waters Industrial Water
Class II (e.g. cooling, etc); other coastal and marine
waters, by their quality, belong to this classification
24 “Class D” waters: for agriculture, irrigation,
livestock watering etc; Industrial Water Class II (e.g.
cooling, etc) and other inland waters by their quality
belong to this classification
22
Dry weather and Wet weather Flow rates in
Profiled Manholes
The dry weather flow represents the basic flow of
wastewater in the drains, with absolutely no rainfall.
The wet weather flow rate on the other hand is
includes the basic dry weather flow and the average
44
Optimal Site Selection
Optimal sites were chosen according to the locations
and empirical and observed conditions in the
upstream networks of EDV drainage catchment.
Generally, manholes in the upstream drainage areas
or site which serve the following criteria are
acceptable and preferred treatment sites:
Unfortunately, only BOD and TKN-N loadings were
quantified and modeled in the design process. And
of these parameters only TSS and BOD have specific
standards provided by the policy.
“Conventional and Other Pollutants Affecting
Aesthetics and Oxygen Demand and their Standards
for a wastewater treatment system effluent” are
presented in Table 13.
Note that quoted standards are “limiting 90th
percentile values. But this clause is only applicable
when the discharger undertakes daily monitoring of
its effluent quality otherwise the numerical values in
the table are not to be exceeded once a year”. (DAO
34)
Currently, and according to the baseline study of
PRRC, EDV water quality itself in terms of BOD and
TSS are substantially lower compared to other
esteros. (PRRC 2001) It is not modeled in this work,
how the loadings on each manhole summed up to the
measured BOD5 concentrations in EDV waters of 41
mg/L (value from PRRC 2001). It is assumed that
the introduction of treatment installations in the
upstream conduits will reduce the total loading along
the downstream conduits and will dilute the
concentration of the wastewaters and storm waters
discharged to the EDV.
Detailed clauses on water criteria (which might be
introduced in policy in the future) especially for
combined storm and wastewater treatment systems
such as minimum and maximum, dry/ wet weather
average allowable effluent concentrations at certain or
all stages, will affect the choice of unit operations and
monitoring needed in the proposed system. The
proposed treatment system focuses on the effluents
concentration at the outfalls to EDV and not on
effluents at each of the multiple installations at
multiple sites. The distributed unit operations reduce
load upstream and dilutes constituent concentrations
only at certain locations such that the final effluent at
the outfall will satisfy the set standards. Thus, the
effluent concentrations in the outfalls and not all
concentrations along all the drainage segments matter
more. In wet weather effluent concentrations will be
slightly higher than the set standards. But the
number days when rains would occur higher than the
average wet weather flow rates, is not likely to exceed
30 days or 10% of the year. Considering the 90th
percentile values and the current policy for treatment
systems with daily monitoring, the proposed
treatment system can still pass.
This research calls for further monitoring of the
estero water quality and the assessment of current
water quality criteria. Understanding the bio-geochemical dynamics and socio-economic interplays in
the inter-tidal environment will guide future policies
and policy clauses for sound designs of treatment
systems for estero use, rehabilitation or remediation.
1) Manholes which serve considerable population
and have relatively low flow rates were ideally chosen
for designs such that proposed treatment installations
would achieve significant load reduction while still
being in relatively small scale;
2) Manholes with considerably less downstream
population are also desirable, such that the reduced
loads and constituent concentrations by the upstream
treatment installations will not substantially increase
again as it flows through downstream;
3) Manholes where vacant lands could be available or
acquired especially for above-ground treatment
infrastructures. Realistically, this criterion is difficult
to fulfill;
4) Manholes which are frequently flooded due to
combinations of very low elevation, negative slopes
and drainage clogging are also purposively considered
to be ideal sites for treatment installations, as
treatment installations would have to reconstruct the
existing drainage structure and can be made to
accommodate rain waters as temporary retention
spaces or flow routes.
It is suggested that other systematic assessments
systems e.g. EIA not covered in this thesis,
investigate, weigh and manage the impacts of the
proposed treatment installations. The effects of the
proposed treatment system in the overall functions
and hydraulic dynamics of the drainages in EDV are
discussed in the complimentary thesis of Balogh
(2008).
Figure 28 shows the selected manholeconduits to introduce the proposed inline combined
storm and wastewater treatment.
Note labels on the map for Figure 26 and 27.
Figure 26 Projected Manhole Data 2016,
Dry and Wet Weather (Balogh, 2008) ►
Figure 27 Projected Manhole Data 2025,
Dry and Wet Weather (Balogh, 2008) ►►
45
Projected Manhole Data, 2016
Outflowing data for the manholes.
105
3.8
10.5
1063
Label guide:
Manhole ID
Dry weather flowrate [Liter/sec]
Dry weather + Average rain flowrate [Liter/sec]
Cumulated population
$
1
Color shading - Subcatchments
Wide frame - Catchment of an outfall (Outfall ID )
101
10.8
29.7
7047
55
9.6
26.4
6043
$
1
$
1
267
1.1
1.9
200
60
40.1
90.3
27281
200
0.9
2.7
1448
$
1
$
1
$
1
4
134
7.7
13.2
2089
19
13.3
23.6
4467
$
1
$ 2112.2
1
$
1
177
10.5
26.5
8882
94
80.7
206.2
54759
197
7.3
18.7
7437
81
122.3
312.4
76118
$
1
$
1
21.5
3943
74
124.9
320.4
79790
11
46
75.9
15338
$
1
$
1
111
37.2
105.6
23997
63
152.4
399.2
97118
185
56.7
96.6
19519
8
64.5
109.8
24573
205
37.8
94.4
16525
2
$
1
5
124
33
92.6
21487
$
1 114
35.6
100.7
23137
801
$
1 2659.2
71
36.8
91.3
16088
$
1
12680
$
1
39
17.3
34.3
8291
$
1
$
1
243
66
112.9
24573
$
1
$
1
$
1
$
1
$
1
68
138.8
357.6
91371
$
1
123
34.3
96.5
22273
99
78.6
199.7
52543
$
1
$
1
128
26.9
73.9
19354
1
193
167.3
445.1
113585
903
5
10.4
1979
902
3.4
10.4
4389
51
162.8
431.2
108456
$
1
$
1
154
16.4
31.4
7625
$
1
$
1
$
1
$
1
$
1
77
9.7
29.7
2126
56
160.8
424.8
106090
171
13.8
23.2
6344
44
$
1
$
1 164.3
435.7
$
1
110087
$
1
905
1029
36.1
88.9
17007
$
1 13.7
28.7
18561
909
41.5
99.9
18561
6
252
3.5
6.1
1552
$
1
253
3
$
1
$
1
906
9
23.1
36.9
10460
10183
28.3
73
14463
10
4805
230
96
171.4
42698
251
20
53.4
11284
225
124.5
247.3
56787
247
41.4
64.9
19932
227
44.6
73.3
21681
$
1
$
1
908
$
1 17.7
35
8
173
42.1
66.5
14.8 20303
45.1
8325
$
1$
1
$
1
40
80.9
131.6
37899
$
1
$
1 1.9
3.2
860
$
1
$
1 1090
12.2
37
$
1 7210
$
1
265
43.3
69.6
20931
181
11.9
31.7
7716
907
12.4
18.9
5500
10159
19.9
55.7
10976
$
1
$
1258
$
1
7
161
0.3
0.5
120
1089
4.6
14.4
4247
248
37
56.4
17809
$
1
260
79.7
128.5
37535
261
26.1
35.3
12573
263
32.9
48.5
15854
262
28.7
40.2
13787
$
1
$
1
256
11.2
13.7
5394
$
1
$
1
$
1
$
1
$
1
224
124.2
246.6
56600
1
$$
1
$
1 911
475.2
1044.6
248435
A
S
I
P
G
R
I
V
E
R
F
BaloS0FT
0 50 100
200
300
400
500
Meters
Drawing code: PF2016
Manila, Estero de Valencia, Hydraulical analysis, 27/02-2008
Projected Manhole Data, 2025
Outflowing data for the manholes.
105
3.8
11.6
1329
Label guide:
Manhole ID
Dry weather flowrate [Liter/sec]
Dry weather + Average rain flowrate [Liter/sec]
Cumulated population
!
.
Color shading - Subcatchments
Wide frame - Catchment of an outfall (Outfall ID )
101
10.7
32.9
8808
55
9.6
29.3
7554
!
.
!
.
267
1.2
2.1
250
!
.
4
177
11.3
30
11102
!
.
!
. 21
13.1
!
.
11
49.6
84.6
19172
74
132.6
362
99738
!
.
63
162.3
451.5
121397
185
61.2
107.8
24398
!
.
!
.
243
71.3
126
30716
5
902
3.7
11.9
5486
2
193
178.4
903
503.8
5.4
11.8 141981
2474
!
.
84.9
232.4
68449
!
.
!
.
51
173.5
488
135570
!
.
!
.
112.5
28922
!
.
!
.
205
40.8
107
20656
71
39.7
103.5
20110
!
. 28
66.8
15849
!
.
39
18.7
38.5
10364 154
17.7
35.1
9532
77
10.5
33.9
2657
56
171.3
480.8
132612
!
.
171
14.8
25.9
7930
!
.
!
.
44
!
.
137609
1029
38.9
100.6
21259
905
23201
252
3.8
6.8
1939
!
.
3
!
.
!
.
906
25
41.1
13074
10159
21.5
63.2
13720
10183
30.6
82.8
18079
258
46.7
77.5
26163
!
.
181
12.9
36.2
9645
907
13.4
21
6875
251
21.6
60.8
14105
!
.
!
.
!
.
!
.!
.
10
230
103.6
191.7
53373
!
.
260
86
143
46918
248
39.9
62.6
22262
!
.
263
35.5
53.8
19818
262
30.9
44.4
17233
!
.
!
. 253
2
3.6
1075
261
28.2
38.9
15716
!
.
256
12.1
15
6742
!
.
!
.
!
.
!
.
!
.
224
134
277.3
70750
.
!!
.
!
. 911
510.4
A
265
16
247
51.3
44.7
10407
72.2
24914
173
45.4
73.9
25379
!
.
!
. 908
!
. 19.1
39.4
1177.4
310543
!
.
!
.
!
.
227
48.1
81.6
27101 40
87.3
146.5
47373
!
.
6006
161
0.3
0.6
150
1089
5
16.3
5308
9
225
134.3
278.2
70983
!
. 114
36.3
!
. 175.1
493.2
!
.
!
. 15
32.1
8
!
.
!
.
124
33.5
103.3
26859
801
68
147.6
404
114214
!
.
!
.
909
44.8
113
23201
!
.
111
38
118.1
29996
!
.94
!
.
8
69.6
122.5
30716
7
81
129.8
352.7
95148
!
.
!
.
123
34.8
107.7
27841
99
82.6
225
65679
197
7.8
21.2
9297
!
.
6
!
.
!
.
24
4929
128
26.9
81.9
24193
1
!
.
134
8.3
14.7
2611
19
14.3
26.3
5584
60
43.3
102.5
34102
200
0.9
3
1810
S
I
P
G
R
I
V
E
R
F
BaloS0FT
0 50 100
200
300
400
500
Meters
Drawing code: PF2025
Manila, Estero de Valencia, Hydraulical analysis, 27/02-2008
Trina Go Listanco
TRITA LWR MASTER
Table 13. “Effluent Standards for Conventional and Other pollutants in Protected Waters Category I and II, and in
Inland Water Class C.” adapted from DAO 35 – 1990, p. 5 and other practiced standards in Sweden and E.U. Note:
No effluent standards exist for phosphorus and nitrogen in the Philippines
Parameter
Unit
pH
Philippine
Effluent
Standards
Swedish
Standards
Effluent
E.U. Effluent Standards, E.U.
Directive EEC 271/91
6.5 -9
COD
mg/L
100
< 70 ppm, not officially
used, but in actual practice
< 125 ppm
BOD5 at 20 °C
mg/L
50
BOD7 < 10 or 15 ppm
< 25 ppm
Total Suspended
Solids
mg/l
70
Total Coliforms
MPN/
100 mL
10000
Total Nitrogen
ppm
-
< 10 or 15
< 15 for plants with < 100,000 pe
nominal design
< 10 for plants with > 100,000 pe
nominal design
Total Phosphorus
ppm
-
<0.3 or 0.5
< 2.0 for plants with < 100,000 pe
nominal
design)
< 1.0 (plants > 100,000 pe nominal
design)
< 35 ppm
The selected drainage segments or roads for
proposed treatment installations are highlighted in
Fig. 28, but their area dimensions (width and lengths)
are not definitive and not scaled according to the
designed dimensions. Note that the selected sites are
actually valid only in the immediate downstream
(outlet) of the selected manholes, as all derived flow
rates, loading and population figures are in this thesis.
All profiled manholes and conduits in EDV with
their differences in loading, BOD and TKN
concentrations are estimated and presented in
Appendix I including values for highlighted arbitrarily
chosen manholes.
Note that 2 manholes along DM 10 which is a major
drainage line for flood control, Manhole 94 and 44
were also selected for RBC shaft installation. These 2
manholes were chosen to “re-treat” the incoming
wastewater previously treated in manhole-installations
further upstream.
Table 15 presents selected manholes and their
wastewater characteristics and flows (Flow rate
estimations also discussed in Balogh, 2008) BOD and
TKN concentrations estimated from (Qian et al 1998
and Metcalf and Eddy 2003)
Inline physical separation methodologies such as
tangential filters provided the principle and idea of
continuous filtration or screening without needing
external power sources. Biological treatment system
is theoretically more effective in Philippine setting
than chemical treatment methods, because of the
temperature factor. Biological activity for wastewater
treatment is higher and conducive to effective
degradation of organic constituents, whereas chemical
treatment involves “adding” constituents to the
influent wastewaters (Metcalf and Eddy 2003). The
annual temperature in Manila does not fluctuate so
much in a day or in a year, such that a more
consistent treatment can be expected throughout the
year.
There are different principles for biological treatment.
Among possibly many others, “attached, submerged
and suspended growth systems” were reviewed. And
of the 3 widely practiced biological treatment
methods, the attached growth system offers the
simplest operation and maintenance. Submerged
growth systems are mostly proprietary units and
would require backwashing. Suspended growth
systems e.g. activated sludge processes, require
operation conditions needing “special attention for
process control” e.g. regulating return sludge,
maintaining dissolved oxygen levels etc. (Metcalf and
Eddy 2003, p. 689)
Although submerged and suspended growth systems
are reviewed to be reliable and effective, their costs,
process control, operation and maintenance tend to
be more sophisticated than that of attached growth
systems.
Process Selection and Choice
Among many other treatment technologies surveyed,
the models used for this thesis design are chosen to
be the most appropriate for EDV. The evaluation is
a summary of “appropriateness” criteria: low cost,
operable and reliable (EPA 2000), and the desired
inline configurations.
48
Fig. 28 Map showing profiled manhole locations in EDV overlaid on Google Map image (taken year 2005) of the site
49
Trina Go Listanco
TRITA LWR MASTER
Table 15a. Selected manhole and their estimated flowrates and wastewater characteristics for years 2016 and 2025
YEAR
2016
Manhole
Id
Dry
weather
flow
rateday
Avg
(m3/sec)
Wet
weather
flow rate
Dry + Avg
rain
Population
Daily cons
(Liters/day)
BOD conc
DRY
[mg/l]
BOD conc
DRY+avg
rain [mg/l]
TKN
Concentration
Dry (mg/L)
TKN
Concentration
Wet (mg/L)
Avg
(m3/sec)
101
0.01
0.0185
8833
105
380
221.49
28.5
16.6
114
0.03
0.0621
27499
112
357
204.87
26.7
15.3
60
0.04
0.0608
14989
231
173
114.07
12.9
8.5
94
0.08
0.1321
47931
145
275
168.02
20.6
12.6
44
0.16
0.2750
115809
123
326
194.99
24.4
14.6
200
0.0009
0.0016
1808
41
975
530.96
73.1
39.8
177
0.0105
0.0170
11122
81
491
303.76
36.8
22.7
77
0.0097
0.0179
3846
219
183
99.52
13.7
7.4
253
0.0019
0.0024
1079
152
263
205.71
19.7
15.4
171
0.0138
0.0176
7944
150
267
209.21
20.0
15.6
71
0.0368
0.0590
18704
170
236
146.89
17.6
11.0
205
0.0378
0.0608
19251
170
236
146.55
17.69
10.9
11
0.0460
0.0581
19231
207
194
153.15
14.5
11.4
8
0.0646
0.0829
30804
181
221
172.03
16.5
12.9
263
0.0329
0.0393
19866
143
279
234.30
20.9
17.5
227
0.0446
0.0562
27160
142
282
223.73
21.1
16.7
40
0.0809
0.1014
47471
147
272
216.73
20.3
16.2
230
0.0960
0.1266
53487
155
258
195.60
19.3
14.6
181
0.0120
0.0201
9663
107
374
222.87
28.0
16.7
251
0.0200
0.0337
14135
122
327
194.33
24.5
14.5
Outfall02
0.0034
0.0063
4050
73
551
299.94
41.3
22.4
Outfall05
0.0140
0.0197
7293
166
241
171.66
18.0
12.8
Outfall09
0.0415
0.0638
23199
154
259
168.24
19.4
12.6
Outfall06
0.0231
0.0287
13109
152
262
211.14
19.6
15.8
Outfall07
0.0124
0.0151
6851
157
255
210.49
19.1
15.7
Outfall08
0.0177
0.0248
6011
254
157
112.35
11.8
8.4
Outfall
EdV
0.4753
0.7070
287604
143
280
188.32
21.0
14.1
50
Table 15b. Selected manhole and their estimated flowrates and wastewater characteristics for years 2016 and 2025
YEAR
2025
Dry +
Avg rain
Population
Daily cons
(Liters/day)
BOD
conc
DRY
[mg/l]
BOD
conc
DRY+avg
rain
[mg/l]
TKN
Concentration
Dry (mg/L)
TKN
Concentration
Wet (mg/L)
Avg
(m3/sec)
101
0.0108
0.0294
10906
85
470
171.73
35.2
12.8
114
0.0363
0.1012
33954
92
433
155.32
32.4
11.6
QC
Avg
(m3/sec)
Wet
weather
flow rate
60
0.0433
0.0949
18507
202
198
90.33
14.8
6.7
DM10
Manhole
Id
Dry
weather
flow
rateday
94
0.0850
0.2122
59182
124
322
129.11
24.1
9.6
44
0.1753
0.4517
142992
106
378
146.57
28.3
10.9
200
0.0009
0.0026
2231
36
1114
400.90
83.5
30.0
177
0.0113
0.0267
13733
71
561
238.45
42.0
17.8
77
0.0105
0.0304
4749
191
209
72.25
15.6
5.4
253
0.0021
0.0032
1333
133
301
192.47
22.5
14.4
171
0.0149
0.0237
9809
131
306
191.90
22.9
14.3
Outfalls
NL053
NL049
NL050
71
0.0397
0.0939
23094
149
269
113.86
20.1
8.5
205
0.0408
0.0973
23770
148
270
113.07
20.2
8.4
11
0.0497
0.0785
23745
181
221
140.05
16.6
10.5
8
0.0697
0.1140
38034
158
253
154.40
18.9
11.5
263
0.0356
0.0506
24528
125
319
224.60
23.9
16.8
227
0.0482
0.0770
33535
124
322
201.71
24.1
15.1
40
0.0873
0.1386
58614
129
311
195.77
23.3
14.6
230
0.1037
0.1800
66042
136
295
169.85
22.1
12.7
181
0.0129
0.0330
11931
94
428
167.49
32.0
12.5
251
0.0216
0.0555
17453
107
374
145.61
28.0
10.9
Outfall02
0.0037
0.0105
5001
64
630
221.37
47.2
16.6
Outfall05
0.0151
0.0290
9004
145
276
143.59
20.6
10.7
Outfall09
0.0448
0.1010
28643
135
296
131.29
22.2
9.8
Outfall06
0.0250
0.0388
16186
133
300
193.26
22.4
14.4
Outfall07
0.0134
0.0197
8459
137
292
198.33
21.8
14.8
Outfall08
0.0191
0.0366
7422
222
180
93.97
13.5
7.0
Outfall
EdV
0.5107
1.0955
355109
124
322
150.07
24.1
11.2
51
Trina Go Listanco
TRITA LWR MASTER
Table 16. The summary of major decision criteria for manhole treatment site selection
Lateral ID
Manhole ID
Remarks
NL 050
101
Fairly upstream location with low flow rates; intercepts flow from the northern most, less densely
populated parts of catchment (Quezon City)
114
Negative drainage slope; serves high cumulative population, recommended to be redesigned and
reconstructed (Balogh, 2008) possibly during the proposed treatment installation construction
QC
60
(Un-profiled manhole) Serves the northern portions of the catchment; low flow rates.
DM 10
94
Along main drainage (Visayan Main or “DM 10”) collecting and accumulating all flows from the northern
subcatchments
44
Also along main drainage accumulating flows just before discharge to EDV
200
Most upstream manhole of NL 049 with low flow rates but serving at least 2000 people by 2025; close to
informal and low income communities
177
Mid point manhole along NL 049, with relatively wider roads, serves high cumulative population (13,733
persons by 2025)
77
(Un-profiled manhole) Serves, eastern portion of DM 10 along Masbate Street; with estimated high
population (4,749 persons) served by 2025
253
Upstream source in NL051; relatively less densely populated residential and mixed land use area
171
Serves very high population (9,809 persons by 2025); with very low drainage slope; recommended to
be redesigned or reconstructed (Balogh, 2008)
39
Serves 3000 persons (in 2025) in addition to population served by Manhole 171; with relatively low flow
rates
71
Serves very high population in a residential area, close to high density low income and low density high
income communities; may have available open space for treatment installations
205
Manhole in highly populated, low income area; last manhole in NL051 before joining to DM 10
11
Manhole in highly populated, low income area; with negative drainage slope; frequently clogged (JICA,
2000) recommended for “urgent works”
8
Serves very high population, close to commercial establishments; located along major road traffic
263
Serves high population in residential area
227
Serves high population in residential area, close to public institutional spaces and public lands
40
Serves high population in mixed land use area; close to the EDV pumping station
230
Serves high population in mixed land use area; serve as continuation or support to proposed treatment
installations in upstream manholes or sites
181
Upstream source for NL 053; relatively low flow rate and serving high populations in mixed land use
251
Midpoint manhole in NL 053; serving about additional 6000 persons (by 2025) from upstream Manhole
181.
NL049
NL051
NL048
NL054
NL053
Outfall 02
Outfall 05
Outfall 09
Outfall 06
Outfalls are important sites for treatment prior to release of effluents to the EDV. Outfall 02 is the smallest and is the least
demanding of treatment processes and is located in a dense residential community.
Outfall 05 drains residential roads while Outfall 09 and 06 drain areas with mixed land use and roads. Outfall 08 serves
relatively low population and low density residential and school areas.
Outfall 07
Outfall 08
EDV site is highly populated but is not likely to
afford enough number of specialized professionals to
handle and operate multiple installations of fragile
treatment systems. Two of attached growth fixed
film systems: RBC and biotower, with quite passive
maintenance schemes were decisively chosen as inline
biological treatment components of the treatment
system. Table 17 summarizes the different proposed
unit processes of the proposed treatment system and
each of their apparent advantages and disadvantages.
The remarks highlight the rationale behind their
choice and inclusion in the proposed treatment
system. The variety of the site specific conditions in
EDV demands same variety of applicable
configuration or variations to be well suited to these
conditions. For example, the dimensions of road
inlets are not always maintained to standards; the pipe
diameter is not the same for all drainage lines; and the
manhole depth are different depending on the date of
construction and design. The designs for each of the
units presented in this thesis are generic models or
prototypes that could be further redesigned to fit
exact conditions of site selected for them.
The summary of remarks and rationales for choosing
and proposing the proposed system components for
the EDV site based on reported failures and
comments in published literatures are presented
below.
52
Why drilled metal plates for inlet screens?
But as the subsequent biological treatment installations i.e. RBC requires influent wastewaters to
have been effectively removed of grit, debris, and
excessive oil and grease, the relevance of VSB
installations (especially Variation 3) becomes more
crucial. Although not integral to the proposed
treatment train, the VSB provides support measures
to reduce TSS, grease and oil from the RBC influent
waters.
Drilled metal screens are presented in Dickenson
(1997) as a sturdy and effective strainer for various
applications. The need for screens in inlets is
imperative because of indiscriminate solid waste
disposal practiced on roads.
Litter and sediments tend to clog drains and reduce
their effective sizes. Metal bar-type strainers have
been adapted in several drains, but the openings and
gaps are still big enough for bits of solid wastes e.g.
dead leaves, plastic bags etc can infiltrate. Metal bars
are also found to be easy to lift and dismantle.
There have been several reports of vandalism and
theft of these drain-screens, making them ineffective,
if not “non-existing” in the site.
Thus, for
infrastructure protection, heavier drilled metal plates
difficult to carry away and with locking feature is
practical to consider. Longer drilled metal plates
would also mean increased total area of opening for
drainage, making solid screening possible even in
sudden heavy downpour of rain.
It has been observed that street sweepers sometimes
sweep the road dust and soot and other litter into the
inlet drains. Apart from correcting this practice
through education and training of employed sweepers
or public, infrastructural measures should also plot to
better road drainage maintenance. Smaller openings
in the strainer would mean less bulky solids
penetrating the screens and would “signal” the
message that: road drainages are not supposed to
collect solid wastes.
A finer screen installation can be made to handle the
smaller solids, collect and separate them from the
influent wastewater, in preparation for the successive
treatment units.
Why Rotating Biological Contractors (RBC’s)?
RBC’s are among the attached growth biological
treatment systems that are compact and cost efficient,
two of the most important criteria for EDV site and
for proposed combined storm and wastewater
treatment systems.
In Najafpour et al (2006), aerobic RBC systems were
modeled as an applicable attached growth system for
treating high level organic compounds in food
canning wastewaters. In the same work, the authors
refer to Yamaguchi et al (1999) in enumerating the
general advantages of an aerated RBC as: “short
hydraulic retention time (HRT), high biomass
concentration, high specific surface area, low energy
consumption, operational simplicity, insensitivity to
toxic substrate, less accumulation of sloughed biofilm and partial stir.” (Najafpour et al 2006)
The treatment principle primarily involves substrate
removal through biofilm processes and the alternate
exposure of wastewater to air for aerobic biological
degradation of organic compounds.
Other advantages over trickling filters and activated
sludge are reported to be: “a longer contact time (8 to
10 times longer than trickling filters), a higher level of
treatment than conventional high-rate trickling filters,
and less susceptibility to upset from changes in
hydraulic or organic loading than the conventional
activated sludge process.“ (Cortez et al 2008)
The RBC is also suitable for high density urban
municipalities or communities since typical
installations can be covered to avoid odor and noise
nuisance. The influent-effluent quality achieved by
the RBC’s in operating treatment plants are reported
to be high according to manufacturer.25
However, Fujie et al (1983) has found that although
“RBC has a higher power economy than activated
sludge process, the latter has higher BOD removal
rate per unit floor area” (RBC only about one-third
of the activated sludge process). The authors have
concluded that RBC’s are “less suitable for large
scale” installations and are more appropriate for small
scale applications where the area of the tank is not a
major issue. Further, it was recommended that flow
balancing tank be used to conserve power economy.
Why tangential screens for fine screenings?
Tangential filter screens were described in Metcalf
and Eddy (2003) as one technology appropriate for
both storm water and wastewater screening. They are
exactly designed to be installed along the drains for
dry or wet weather conditions without compromising
the drainage efficiency of the canal and without
reducing the inflowing water head.
In essence, the tangential filters provide dry and wet
weather filter space “in line” with the drains by
diverting or “re-routing” the storm or wastewater
flow into a separate chamber with a cylindrical filter
media and thus theoretically lengthening the drainage
path.
The chamber is designed to be easily
disassembled for collecting the filtrates manually.
Further, its chamber can be redesigned to function as
a settling tank for additional TSS or BOD removal.
This filtration system is also independent of any
power or mechanical component. For maintenance, it
only requires the collection of filtrates in the bin and
putting the bin back. Although this routine can be
easily introduced to the schedules of street sweepers
and drainage maintenance crews, special equipments
may be required for bigger installations. These filters
can function and can be maintained in wet season.
25 IWK is a German firm manufacturing made to
order and packaged RBC installations, it has claimed
that a raw sewage: 200-400 gBOD/ m3 can have
effluent BOD = 10-30 g/m3.
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Table 17. Summary of Published Advantages and Disadvantages of Selected Treatment Processes
Unit Process Description
Advantages
Disadvantages
Drilled metal plates to be installed in all possible road
inlets and manholes
Easy to clean and maintain; reduce solids and sediments in
the drains
Construction and reconstruction cost of road inlets
Tangential filters or chambers along drainages
Easy to operate and maintain; not externally powered
Requires regular maintenance and equipments
Involvement and education of households in wastewater
treatment
Numerous to maintain
Household
VSB’s
Distributed space requirements
Difficult to monitor at different private sites
Potentially efficient for small loadings
Immense demand for household capacity building
Combined treatment for wastewater in drains and for
household effluent
High potential for overloading and “ponding”
Combined household and inlet intercepting VSB
Variation 3
Streamlined and easy to maintain
Exposure of site to public especially, pedestrians
Parallel VSB installations along side drainage canal
Public education and information tool
Take space from sidewalks and gutters
Screens
VSB
Variation 1
Variation 2
Space demanding for high density household clusters
Difficult to maintain
Easy to maintain in “biotower” compounds
Additional aesthetic value
Require vast additional above ground space in “biotower” compounds
Space saving; requires less number of shafts
Overloaded first stage, and inefficient treatment of succeeding stages
RBC
Configuration 1
Cannot be operated / maintained without disturbing traffic and drainage
flow
Difficult to operate in events of extremely high loads
Configuration 2:
Only space requirement is along the drains and less
requirement to acquire private lots
Require installation of “step feed” distribution system or a “parallel type”
distributions system
Efficient BOD Reduction
a) 15 Maximum first stage shafts
b) 7 Maximum first stage shafts
Configuration 3
No overloading of first stage and shafts
Takes too much space; destruction and reconstruction at longer lengths of
drainage, household pipes and roads
Effective BOD removal, no fouling of discs
Disruptive of traffic for maintenance
Probable nitrification in succeeding stage
Costly to produce and takes much time to maintain
Less space, maintenance requirement
Overloaded stages, but can be compensated by supplemental aeration
Fits roads, minimum disruption in traffic
Aeration entails additional cost and maintenance work
Demand simple operation and direct interception of inflow
with high flow velocities
Wide expanse of space requirement
Easy to operate and implement
Requires large amount of area for nitrification
Require installation of distribution system
Biotower
Low maintenance demands
Produce nuisance like odor and flies if operated poorly
54
Among the inordinate failures of the RBC published
by Ross et al (2008), the major setback identified was
related to the structural failure of the shafts. This is
explained by the accumulated weight of the shaft
discs due to biofilm growth that is usually overlooked
in RBC design. The findings confirm suitability of
installing RBC units in small scale but multiple small
sites in the EDV catchment. The designs for such
small scale installations include features for achieving
a steady distributed flow, multiple shafts in tapered
stages. The designed 2m diameter discs will alleviate
dangers of possible shaft structural failures.
Since the RBC systems envisioned for this thesis
designs are aerobic in nature, sufficient oxygen supply
and transfer is crucial. However, underground
installations of RBC shafts, lower than drainage
pipes’ invert elevations can short-change the supply
of air even at high ceiling heights. Metcalf and Eddy
(2003), presents an air-feed RBC installation where
air diffusers mounted in the tanks serve as oxygen
supplier and shaft rotation driver. Such model, can
address the inherent limitations of an “inline” RBC.
RBC concept is thus theoretically ideal for an “inline”
combined storm and wastewater treatment system
because of its small demand for space and its straight
forward operations. The only major disruption
caused by its inline installation and operation is
traffic. The surface aeration and biofilm growth can
be achieved in drainage and can be supplemented
with aeration system. The treatment reaction also
resembles a “plug flow” reaction providing
continuous treatment of storm and wastewater along
the drains, and without compromising the drainage
efficiency of the pipes. The tankage of the RBC units
can also serve as small detention cells which can
theoretically, lengthen the drainage path of the rain
waters.
treatment- step 1” for substantial BOD reduction to
achieve conditions for nitrification in a “biotower”
(“biological treatment- step 2”). If RBC stages will
be added to achieve nitrification, the length of the
installation covers more than 2 manholes and 1
conduit. This will translate into deconstructing and
constructing more underground pipes.
The
“biotower” comes with the risks of structural failures.
Other alternative compact systems are presented in
table 18 including pertinent reasons why such
systems are less ideal for an “inline” treatment system
in EDV.
In summary the treatment train for the combined
storm and wastewater treatment along the drains
needed a continuous system that will operate not just
in dry weather, but also in wet weather. The system
has to be responsive to demands for low cost and
compact alternatives at the same time contribute
directly or indirectly to storm water management.
For these, simple physical and biological treatments
i.e. inline filters or screens and attached growth
biological treatment systems are found most suitable.
Among many other physical and biological treatment
operations, the “inline” filter series, the RBC and the
“biotower” stood out because of the simplicity of
their operating principles and their flexibility to be
redesigned for “inline” installations along the
drainage spaces.
The attached growth system
provided advantages of low energy; low space and
low cost, over other biological treatment procedures
e.g. submerged or suspended growth systems or their
combinations. Its operations were reviewed to not
need much “process control”. The envisioned
treatment sequence and the theoretical performance
are discussed in the next chapter.
Proposed Processes and Sequences and
Variations
In general the whole treatment process for the
treatment system is a combination of selected
physical treatment and biological treatment methods.
It is a collection of reviewed compact and costefficient treatment units that can be easily installed in
multiple sites along or along side the roads and can
be developed in stages. In principle, the system
promotes decentralization, community stock taking,
involvement and education in drainage and
wastewater units and systems. There is much effort
to design the system to be easily understandable,
labor friendly and potentially community based. The
system designs adhere to altruism of “holistic
technologies” and community development, such
that technology should be understood and
implemented to benefit local people. The units
proposed were reviewed to be among the least and
simplest maintenance requirements e.g. RBC and
“biotower” (trickling filters) that would demand not
only skilled professionals but also community
residents as actors or employees. The choice criteria
and basis for unit selection is discussed in more depth
in the chapter “Comparative Summary”.
Why “Biotower”?
Gonzales (1996) has evaluated available aerobic
biological treatment systems for aquaculture
wastewater application, including lagoons, activated
sludge processes, RBC and trickling filters. The
applicability of the biotower (trickling filter with
synthetic packing) and RBC even for wastewater
treatment in aquaculture and production, (higher
organic loading than typical municipal or combined
storm and wastewaters), can be summarized in two
important criteria for EDV applications: 1) moderate
demands for operation and 2) moderate costs.
Apparently, the RBC and Biotower installations
render the same function as a treatment system, but
their main goals in EDV site differ although highly
related. The RBC units are more compact systems
that can be reconfigured along or along side the
drainage lines, below the ground, under the road
spaces. If the “biotower” installation would have
been made to treat the primary effluents, much larger
filter areas and land would be needed above the
ground, to satisfy its efficient areal and hydraulic
loading. Thus, the RBC is essential as “biological
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TRITA LWR MASTER
Specifically, the treatment processes includes physical
separation of solids for preliminary treatment;
attached growth system: (Rotating Biological
Contractor) RBC for first step biological treatment;
and trickling filter (“Biotower”) as the 2nd step
biological treatment process. One possibility of
treatment sequence variation includes Vegetated
Submerged Bed (VSB) unit, with combined physical
and biological treatment processes, for “pre-RBC”
and “post-biotower” treatment (Variation 3 and
Variation 4). All treatment units are fitted along or
along side the drainages or roads, except for
“biotower” installations which require specific land
area above the ground. The system aims to maximize
the existing spaces under roads by vertically
extending the drainage lines, optimizing sidewalk
spaces while minimizing public health and safety risks
and improving overall hydrological and community
landscapes.
The process sequence begins with a or a series of
filter units using strainers and surface type or depth
type filter screens to separate, collect and trap wide
range of solid particles in the wastewater and storm
water streams in the drains. The solid separation is
succeeded by biological treatment systems e.g.
attached growth –fixed film systems. The RBC units
are introduced first to reduce BOD of influent waters
and simultaneously aerate and degrade organic
components mainly through biofilm consumption of
influent substrate. There are 2 proposed RBC unit
configurations in this thesis, the details of which is
discussed in detail in the Design chapter. The
dislodged biofilm components are then filtered out
and collected in a post RBC screen. Then, the
wastewater proceeds to a buffer basin from where it
will be pumped up to be distributed over a
“biotower” or a trickling filter with plastic packing.
The “biotower” units also functions as an attached
growth - fixed film system; and are designed to
further reduce BOD and introduce nitrification
process and total coliform reduction. The biosolids
produced in each step is proposed to be managed
within the subcatchment or within the community;
and will be discussed in a separate chapter. Each of
the units’ designs is detailed in the subsequent
chapters.
There are 2 possible variations of process sequence
proposed and discussed in this thesis: one that uses
more mechanical screening and filters and the other
that introduces vegetated submerged bed (VSB)
technologies. Latter, can be further varied depending
on the conditions of the sites.
treatment unit.” The second part is the beginning of
combined mechanical (tangential screens) and
biological treatment method. The first biological
treatment is a staged RBC unit or a series of RBC
shafts mounted along the drains or along side the
drains and are partially submerged (40%). The RBC
unit is the “core” of the “inline” treatment system
that operates an attached growth system, capable of
exposing wastewater to air for needed oxygen and air
while the biofilm grows, adsorbs and degrades
organic constituents in the influent wastewater as
they flow through. This treatment process is
expected to reduce the BOD of influent wastewaters
considerably in preparation for the next biological
unit process. Typically, RBC units are externally
powered, but since installations of power pumps and
engines for an RBC shaft introduces additional public
risks along roads and underground along side
drainage lines, the RBC shafts can be further
designed to be “self-supporting”. The RBC unit
comes in a series along a lateral, with a maximum of 7
shaft units that may be with variable disc surface area.
For this design exercise, a standard surface area and
shaft dimensions was fixed and investigated for its
effects on BOD removal. The maximum number of
shafts in a series could be variable as well, depending
on the target effluent concentration and the target
first-stage sBOD loading i.e. 15 g sBOD/ m2*day (as
suggested in Metcalf and Eddy, 2003). In the
resultant calculations, only 7 shafts were taken to be
in operation, and gave acceptable theoretical results
for BOD removal. The maintenance and “by – pass”
conditions, for RBC units are also important and will
be discussed in detail in the subsequent chapter on
Design.
The third component is another biological unit
process with an attached growth, fixed film system.
A trickling filter alongside the drainage lines will have
a standard plastic packing with 6.1 meter media
depth. The “biotower” units will function for
combined BOD removal and nitrification. These
“biotowers” could be installed closer to the EDV
outfalls or could be installed in smaller scales but in
multiple sites aster the RBC units.
The biosolids produced in the biological treatment
units are proposed to be handle within the EDV
catchment. From a review of existing technologies
for biosolids management and use, 2 selected
technologies are considered viable for EDV.
The viability of biosolids treatment is judged mostly
on the ease and scale of operating an installation.
Since biosolid components of the treatment effluent
includes mostly fine filter screenings and sloughed
biofilms, methods such as alkaline stabilization and
composting, already adapted in the Philippine Solid
Waste Management Act, are deemed to easily suit
communities or cluster of communities and their
“Materials Recovert Facility”. The assessment of the
existing “MRF’s” in the EDV site is beyond the
scope of this thesis, but is important to evaluate and
develop for future integration to the proposed
Process Identification and Sequence without VSB
The combined “inline” storm and wastewater
treatment system begins in the physical separation of
solid waste and sediments from the water flows.
Simplest method is by installing screens in road canal
inlets. The maintenance of such inlet screens depend
mostly on regular clearing and de-clogging.
Traditionally, this process is termed “preliminary
56
These biosolids management unit processes are
briefly presented as an integral component of the
entire EDV combined inline storm and wastewater
treatment system.
Unfortunately, phosphorus and total coliforms
removal can not be quantified for this design exercise
due mostly to the lack of baseline information on
site’s wastewater constituents and other proxy values.
It is sufficient to say that these constituents will be
handled by other proposed installations not designed
in site-specific detail in this thesis, but are mentioned
as “support” or options for constituent removal e.g.
vegetated submerged beds (VSB).
The efficiency of the proposed support unit and
installations can not be assessed beyond what has
been mentioned in published literature. The general
treatment unit operations layout, without the VSB
support units, is summarized in Fig. 29.
applicable for the proposed VSB treatment unit.
Further studies are needed to assess local
environmental impacts of such macrophytes. The
macrophytes, apart from the adding aesthetics to site,
also serve tools for public education and information
on wastewater treatment science and urban ecology.
The maintenance of such VSB systems can also
mobilize community efforts for improved sanitation
and quality of living environment.
Variation 1) Household VSB type
Variation 1) introduces the VSB on site, to treat
household primary effluents prior to discharging the
partially treated wastewater (septic tank effluent) into
the drainage line. (Fig. 31)
This variation depends largely on how clusters of
households in the community are willing to adapt
such system, their willingness to allocate land, space
and time. This also banks on the social capital of
neighbors in participating in the construction of
communal on-site septic tank effluent treatment
system.
The implementation of this variation entails much
public education and capacity building for
households involved, and touches on organizational
learning and cultures in ecological sanitation.
Unfortunately, this thesis can not provide the detailed
assessments of this variation for each potential site,
but only suggests a generic model or prototype
discussed in the subsequent chapter. The design is
nonetheless applicable to areas with limited spaces.
Note that the designs of such VSB are lifted from the
recommendations in the Design Manual of EPA
(2000).
Another possible on site solution, similar in principle
to the household-on site VSB system, is referred to as
the “upland-wetland” system.
This system is
described as a sand mound, or above ground filter for
treating domestic wastewater, in the report:
“Treatment of Domestic Wastewater by a
Constructed Upland-Wetland Wastewater Treatment
System” by House et al26 Further assessments of this
on site domestic wastewater treatment system is
outside the scope of this thesis work, but the idea and
principles it provides is of potential relevance to the
proposed EDV wastewater treatment system.
Process Identification and Sequence with Vegetated
Submerged Bed (VSB)
This chapter takes off from the above mentioned
proposed “process sequence” and introduces the
possible applications of VSB treatment installations
in the system.
Since RBC units are not
recommended to handle raw municipal wastewater,
primary settling and filtration techniques for pre-RBC
treatment, to reduce debris and excessive grease, are
needed.
The VSB support treatment processes involve
constructed wetlands treatment mechanisms and biomechanical treatment principles, in a smaller scale
and usually closer to wastewater sources. The VSB
system provides combination of physical, geochemical and biological treatment that can further
enhance the constituent reduction at multiple sites in
prior to the RBC units. These installations or train of
installations can be introduced at several points along
the “inline” treatment system e.g. in pocket areas of
house clusters, or alongside sidewalk plots, before
RBC and “biotower” units or/ and after.
There are different possible arrangements and scales
for VSB applications in different sites, e.g. VSB fitted
for residential clusters, VSB incorporated “inline” on
public lands e.g. sidewalk, gutter installations or road
island plant boxes.
Four of such variations are presented in this thesis.
However, the detailed assessments of site specific
VSB beds and designs are not. Instead, a generic
prototype design, applicable for installations
alongside drainages or sidewalks (Variation 3) is
proposed.
The adaptation of these proposed designs, like other
proposed components of this thesis will actually
require further field and pilot studies and surveys.
Macrophytes have been reviewed for the designed
VSB prototype. This thesis mentions species known
to have nutrient removal capacities according to
other constructed wetland studies and may be
26 Internet source:
http://www.ncsu.edu/ncsu/wrri/reports/house.html
,Accessed: February 2008
57
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TRITA LWR MASTER
Table 18. Summary of reported failures of other treatment systems according to capitalization, operation and
maintenance and reliability.
Treatment System
Mechanical and
automated grit
systems
Purpose
Physical separation
of solid wastes in
wastewater streams
Capitalization cost
Operation and
maintenance
High capitalization
cost for acquisition
and retrofitting
Demands reliable
and consistent
power in operation
Demands space
under or above
ground
Bulky and space
demanding,
Difficult to retro fit
for EDV inline
spaces
Reliability
Highly reliable if
maintained well
Public risk if
installed unguarded
Demands special
technician for
operation and
maintenance
Settling tanks and
clarifiers
TSS reduction
High costs due to
space requirement
(above ground or
underground) and
structural properties
Demands specially
skilled personnel to
operate and
maintain
Widely used in
wastewater
treatment plants
Activated Sludge
processes
Organic constituent
reduction
High cost of some
proprietary
technologies
Demands specially
operated and to
maintain
Proven reliable and
compact among
other benefits (e.g.
Methane gas
production) in many
reports
Demands special
facility for produced
“biosolids/ sludge”
Requires critical
monitoring and
process control
High and
continuous demand
for energy
Require controlled
loading and
sensitive to shock
loading unless,
provided buffer
storage for variable
loading
High hydraulic
retention times
Granular Sand bed
filtration
Organic constituent
reduction
High cost for
retrofitting and
acquisition
Demands specially
operated and to
maintain
High and constant
demand for energy
Demand little space
Requires much
attention and
monitoring
High and
continuous demand
for energy
Variation 2) Household + Inlet VSB Type
The proposed Variation 2) introduces the VSB not in
exactly on-site, but “subtly” off site. The bed is
installed at the end of individual household
wastewater pipe oriented towards the drains, and just
before it intersects with the drainage line. This VSB
installation variation is made to handle primary
effluent including grey waters an individual
Proven reliable and
compact among
other benefits (e.g.
availability of
needed materials)
Controlled loading
required and also
buffer storage for
variable loading
household before wastewater joins the drains. The
same VSB bed is made to take some more fraction of
wastewaters diverted from the drain. The designs for
Variation 2) would require substantial space for
effective treatment and safe functioning. Thus, it can
only be applicable for very low density residential
areas. Its implementation would depend largely on
the willingness of the community residents to
transform and possibly maintain treatment spaces,
58
handling not just their domestically produced
wastewater but also the diverted influent from the
road canals. A longitudinal VSB along a drainage
pipe that takes in wastewaters from households along
its slope through multiple inlets would entail much
coordination and highly specific estimations of loads.
This proposed variation will have to engage not just
clusters of houses but households of a subcatchment.
Thus, this thesis can only propose this variation
without detailing the designs of VSB units. (Fig. 32)
Variation 3) VSB Along the drainage line, single inlet
Variation 3) introduces the VSB component off site
of the households, but parallel to the drainage. Like
in the suggested configuration in Variation 2), a weir
is put across a drainage pipe to divert a portion of the
water flow into the VSB installed parallel all through
out a drainage pipe segment. The outlet of the VSB
unit reconnects downstream in the same drainage
pipe. It can be made to operate only during peak
loadings in the day such that it would function as a
batch-reactor, and be allowed sufficient resting when
not in use or when flow in the drains are minimal.
Unlike in Variation 2), no raw domestic wastewaters
are allowed to discharge in this VSB. The only inlet
and inflow is from the drainage pipe. It is thus,
necessary to either provide individual on site
treatment facilities for individual households or
construct another, small diversion pipe for household
effluents that will convey the domestic wastewater to
the next conduit downstream.
This type of installation can be mounted along
sidewalks, following the general slope from the invert
elevation of the drainage line. Variation 3) is a set up
that will require use long narrow vacant lands (0.8 m
– 1 m) to accommodate reliable flow diverted from
the drainage lines. It functions similarly as “slow rate
filtering system” and “horizontal trickling filters”
(EPA 2000). Also, these installations can be put
before or/ and after the RBC units in conjunction
with other mechanical filters. This way, the VSB can
serve multiple functions as a depth-type filter to
reduce primary effluent TSS, and/ or, as effluent
polishing step after RBC units.
This thesis work includes generic design for such a
VSB unit variation that can be adapted in EDV
catchment streets. Since this VSB installation is very
accessible to public and can present risks to public
health, this VSB variation shall be ensured not to
have overland flows or ponds even for weed control.
Moreover, community capacity building for VSB
management and maintenance is needed to prevent
injuries or harm to public.
Note that the designs were lifted from the guidelines
provided by the document EPA (2000), “Design
Manual: Constructed Wetlands Treatment of
Municipal Wastewater” with ample allowance for
safety.
Variation 4) Polishing VSB
Variation 4) is generally similar to the concepts of
Variation 3), where the VSB is introduced in the “in
line’ treatment system. In this variation, VSB
functions mainly as denitrification step after the
nitrification process in the “biotowers” is achieved.
The main VSB will have to be installed within
compounds of the “biotower” installations to handle
the secondary effluent from the “biotower”.
Ideal sites for Variation 4) installation include
“biotower” compounds along the outfalls, where
possible VSB can be mounted along EDV vacant
easements. Detailed land and public survey in the
EDV banks and easements are required for designing
such a VSB variation.
This thesis presents a generic design of a prototype
(Variation 3) which could be modified to suit
Variation 4) for post- “biotower” denitrification
installed inside the “biotower” compound or along
the EDV easements.
All the above mentioned variations are general
suggestions to fit VSB installations in a diversity of
community layouts, drainage spaces, household types
and socio-economy. In such conditions, an “inline
treatment system” and its components has to provide
flexibility and a good range of possible approaches
and design for site specificities. The design presented
in this thesis, is an attempt to provide such a flexible
prototype and to illustrate the need for adjusting VSB
installations for various site applications.
A
prototype for VSB variation 2) is provided in
Designs chapter. And as in variation 2) such VSB is
envisioned as a “supporting” installation to handle
not full loads from the drains but only a fraction of it.
59
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TRITA LWR MASTER
Fig. 29 Process sequence
without VSB units
Biological treatment 1
Fig. 30 Unit operation
layout
for
process
sequence without VSB
units
Fig. 31 Variation
Household type VSB
60
1,
Fig. 32 Variation 2,
Household type with
multiple inlet VSB
Fig. 33 Variation 3, VSB
along drainage line, single
inlet
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TRITA LWR MASTER
Fig. 34 Plans of Variation
3) VSB seen from
upstream, side and from
under the road
(3D Studio Max Graphic
rendering
by
Martin
Varga)
Fig. 35 Variation
Polishing VSB
62
4,
habitat or ecology at least will serve not just plain
conservation goals but a deal of improvement in the
quality of living environment for marginalized
communities. The informal communities along EDV
have been associated with the solid wastes in the
waterways. “Bantay Estero Project” of the DPWH
involves the estero settlers in the maintenance works
of the esteros e.g. providing jobs for collecting
garbage from banks etc. The project adapted
principles of resident involvement, but has not been
successful enough. Seriously involving communities
in EDV maintenance work should not just mean
employing community members but also providing
structural support for systematic community
development.
Macrophyte cultivating as wastewater treatment
ancillary process can provide commercially viable
results. This thesis recommends further assessment
of such approaches involving community and helping
local community economies through wastewater
treatment system schemes.
The success of EDV “clean up” efforts is a function
of social capital among the upstream and downstream
communities. It is thus important to provide a
framework where upstream and downstream
communities can be organized to achieve common
goal of making EDV solid waste-free. A simple
screen, to segment the river length, such as in Figure
36, has probably been employed in other river
rehabilitation efforts.
The screen features retractable flaps of coarse
openings on both edges where solid wastes can be
trapped and be easily lifted and collected. Such
screens will introduce a sense of extended turfs over
segments of the estero to informal and formal
residents. These estero segment-turfs induce and
relegate responsibility for regular cleaning to local
residents. The screen is made to divert the floating
solids to the sides of the waterways where they can be
easily collected from the bank. In case of high
discharges and flow rates e.g. pumping operations or
heavy rain fall events, such screens can be folded for
by-pass. (This idea is also shared with local informal
resident, “Dubert” who is aware of other river
rehabilitation
models
involving
community
stakeholders’ participation)
Floating macrophytes can be introduced to the waters
for minor nutrient removal and aesthetics, although
these plants would possibly clog pumping station
grits and restrict flow. Commercial value of floating
macrophytes can be further studied for possibility of
providing a potential source of livelihood for
community members e.g. fibers for paper,
ornamental plants etc. Also, improving over all
aesthetics of the estero landscape can counter what
the “theory of broken window” implies.
Point of Debate: The Estero de Valencia as a natural
wetland for protection or construction?
Constructed and natural wetlands and their functions
i.e. for wastewater treatment, are constantly being
contested. The esteros and their functions are not
different. Esteros are naturally part of a wetland
system which has been “constructed” or modified
according to its current urban function. In trying to
find and propose ways to rehabilitate and to some
degree, protect the estero and estero spaces, there are
political ecological issues that have to be reflected
upon. While this thesis is not entirely “eco-centric”
and “conservationist” in its goals of rehabilitating an
estero, EDV presents itself as an interesting potential
component for the treatment system apart from
being the target receiving water body to be protected.
Essentially, the effect of the entire treatment system
aims to discharge “cleaner” water to EDV so it can
regain functions of its natural ecology and provide a
number more of “environmental services” to the
communities and to the city. Since EDV itself is
naturally an inter-tidal ecological unit, EDV could
have served its natural and ecological function as a
wetland. The installations of various biological
treatments upstream could temper the organic
loading EDV receives. With these installations, the
remediation and the restoration of function of the
EDV can be brought together. Once EDV has
regained its ecological soundness, it could function
more as wetland that can naturally decompose,
recycle and reuse nutrients in complex ways. It thus
can perform naturally, a polishing treatment for the
proposed upstream treatment train.
Morling (2006) has provided limitations and
performance of “constructed wetlands integrated in
to a modernized wastewater treatment system”. The
experience demonstrated how treatment wetlands can
be converted to adapt activated sludge processes.
There are several challenges to accomplish this
remediation process, and most of them can not be
addressed in this thesis. But this section briefly
enumerates issues and possible ways for EDV
remediation, and its foreseeable effect in the whole
wastewater and storm water use and reuse.
The establishment of the flood control pumping
station reflects a lot on how EDV has been
“engineered” and made to function. The flood gates
and the pumping station highly limit the salinity of
the estero waters, completely changing its natural
ecology and chemistry. This change also came with
the changes in the sociological meaning of the estero
easements. What used to be “water frontages” of
local dwellers became marginal public lands taken
advantaged of by informal sector. Thus, challenging
the current roles of the EDV entails not just technical
efforts but socio political approaches.
The
remediation of EDV as a functioning and healthier
63
Trina Go Listanco
TRITA LWR MASTER
Fig. 36 A vision for the EDV, Photo of EDV on the left taken September 2007; photo on right as envisioned for EDV
Photoshop effects rendered by Andras Varga
Fig. 37 Possible screen applications and designs for a variety of road canal inlets, Photoshop rendering by Andras
Varga
64
Pre RBC – Post RBC filter screens
Designs
Designs presented in this section are rather generic
but considers most of the conditions for the selected
conduits or sites. It is important to note that each
manhole has site-specific conditions that require
further studies and verification to calibrate design
parameters, and to more appropriately provide sitespecific designs for each of the manholes.
The idea of tangential filter to divert portions of
drainage waters specifically, runoff or storm waters,
into a loop while separating selected solid
components without hindering the flow in canals and
pipes.
Because it allows continuous flow of
wastewaters, it is most ideal physical treatment unit
for an inline treatment system.
It provides
continuous screening and space (underground) for
retaining water flows, at least not interfering with the
flood waters as it “re-routes” water flows. This
technology is apparently proprietary but could be
retrofitted to accommodate the EDV site flow rates
and solid waste loads. Such screen is also deemed
best because of very minimal demand for external
power to collect and separate solids (unlike moving
mechanical grits). Also the design and form allows
easy maintenance by manual labor or assisted with
small scale collecting equipments.
The design presented in this thesis for pre-RBC and
post-RBC is a modification of the published
tangential fine screens. In principle it resembles
some of the properties of the tangential filter screens.
A diversion weir is used to re-route raw wastewater
flowing off alongside the drain into a series of
chambers of lower elevations (-5 meters from the
pipe invert elevation). The diverted flow first empties
coarse solids into a cylindrical screen and filtrates
further into a second chamber (approximately 48m3)
prior to flowing into the RBC series unit.
The second chamber for the pre-RBC filter screens is
designed to serve as temporary storage where
settlement of solids can be partially expected (given
the average flow and the computed retention time)
while accumulating finer solids into a shoot at the
bottom most compartment. The shoot is a basket of
micro screen (1.0 µm) that can be lifted off the
chamber for regular cleaning. The details of the
prototype are described in Appendix XI- Drawings.
Figure 38 shows profile of the pre-RBC chamber and
the placement of the retractable cylindrical screen.
Note that the screen has to be supported by concrete
columns. The 2 screens in this chamber are both
retractable and replaceable.
The proposed generic prototype presented in this
thesis with a total effective volume of 48 m3, can
retain waters (flowing at computed average flow
rates) at varying durations. Metcalf and Eddy (2003)
provided a graphic function for settling tank designs
where the percentage removals for TSS and BOD
influents with concentrations of 100-200 g/m3 were
plotted against the retention time. From the graph,
influent wastewaters with TSS concentrations of 100300 g/m3 can be reduced to maximum 40%, at
retention time of 0.5 hours. The summary for each
of the selected sites and manholes are presented in
Table 19.
Inlet screens:
A number of existing road inlets’ photos are shown
in Figure 37, none of which is effective in preventing
much solid waste from roads from entering into the
drainage canals. The constituents to be removed or
at least reduced are solid wastes and some fraction of
suspended particles. This detail is important to
ensure that the succeeding sections of the drains
receive minimal sediments and litter; and to provide
preliminary supporting measures to the next physical
units, where combination and series of filters along
the drainage lines should separate and collect even
finer solids prior to the beginning of the next unit
process, the biological treatment.
For upstream manholes and conduits and road inlets,
increasing the total size of openings of drainage
screens, improve the draining capacity of the road
inlets and alleviate surface overflow of storm waters
to low lying areas. Since road inlets in the EDV
catchment, varies in sizes and dimensions, a generic
road inlet screen designed is proposed in this thesis.
The dimensions of the proposed prototype were
derived estimated from the common road inlet sizes
in EDV catchment and roads.
The material as prescribed in Dickenson (1997) is a
rigid and study metal plate, with thickness of 2 cm,
and with perforations or holes, with about 2 cm
diameters. Inlet screens in drains will result in over all
head loss during rain events, and thus are important
to keep unclogged all the time. The metal screens
can be expanded over longer lengths than the existing
road holes, to increase efficiency of drainages. Since
no definitive length of installation has been
determined in this thesis, the total maximum flow
rate of proposed screens affecting storm run off
drainage are assessed in the hydrological and
hydraulical models presented in Balogh (2008).
The realistic efficiency of the inlet screens is depends
largely in maintenance management as much as its
technical design. Regular cleaning of these inlet
screens is thus imperative all the times. The cleaning
process, which will include removal of trapped solids
in openings and bags, may have to be delegated to
street-cleaning personnel and will have to be
systematized together with other implementation
procedures of the whole wastewater treatment
scheme.
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Trina Go Listanco
TRITA LWR MASTER
Note in Table 19 that a number of sites (given their average flow rates) have retention times in the pre-RBC
chambers of less than 60 minutes. Mechanisms to make the settling of solids through this chamber are suggested to
maximize settling in these chambers e.g. flow breakers or weirs.
Fig. 38 presents several
views of the pre-RBC
filter
and
settling
chamber. The bottommost “chute” is lined
with
micro-screen
bucket for collecting
settled solids. Section
A-A shows the relative
elevations
of
the
chamber inlet, drainage
and outlet
Manhole
Id
Flow
rate
[m3/s]
Flow rate
[m3/day]
Retention
time with
fixed
chamber
volume of
48m3
[mins]
Outfall02
0.0037
13
217.56
0.0105
38
76.49
Outfall05
0.0151
54
52.93
0.0290
105
27.56
Outfall09
0.0448
161
17.86
0.1010
364
7.92
Outfall06
0.0250
90
32.02
0.0388
140
20.63
Outfall07
0.0134
48
59.62
0.0197
71
40.51
Outfall08
0.0191
69
41.92
0.0366
132
21.88
WET
Weather
Flow rate
[m3/s]
Flow
rate
[m3/hr]
Retention
time with
fixed
volume of
48m3
[mins]
66
Table 19. Selected sites
for RBC installations
and expected retention
times on prototype preRBC chamber. Designs
are valid for until year
2025. (Full Table in
Appendix II)
Areal loading of 6 gBOD/m2*day was also
recommended in EPA (2000) but the generic design
in this thesis will not be capable of reducing BOD5 of
125 mg/L to 30 mg/L, in a flow rate of 400m3/day.
The design is intentionally done for small scale
installations only in support of the “combined inline
wastewater treatment system”. To increase the
effective treatment zone length, it is possible to adapt
multiple run race way paths across the VSB. (Fig. 41)
The VSB’s can be installed in phases, along sidewalks
or pocket gardens.(Fig. 42a) In literature, there is no
optimum design for bottom slope, but “generally 0.5
to 1% slope is recommended for ease of construction
and proper draining” (EPA 2000). For proposed
installations, the bed slope should be lower than the
slope of the drain it follows to allow natural draining
to the outlet.
Media layers
The bed media for EDV inline installations are
proposed to have 3 bed layers of different hydraulic
and physico-chemical properties. (Fig. 42b) The
major layer which is the design “bed layer” typically
used for VSB is composed of coarse gravel to allow
sufficient flow through of the influent wastewater.
(EPA 2000) This coarse gravel bed with (40-80 mm
rock) near the inlet and the outlet zone can be mixed
with chips of coconut shell charcoal to provide space
for adsorption and carbon in the anaerobic
environment at the bed. A gravel bed media of 20-30
mm diameter was provided by EPA (2000), to be
generally sufficient for the “treatment zone” of the
VSB. The second layer is an ancillary feature to
provide additional space for influent wastewater
storage and filtration from top or from bottom is a
layer primarily made up of sandy material of calcium
or iron or aluminum rich minerals. This sandy layer
is an additional bed space for the VSB installations
where influent water can be retained for longer times.
The post-RBC filter is also a cylindrical micro screen
installation for collecting biosolids sloughed from the
RBC units and part of the effluent waters. (Fig. 39)
The dimensions of the design are different from the
pre-RBC kind. The post RBC installations functions
mostly for water storage and buffering for pumping
after its filtration. The cylindrical micro-screen is
installed in a primary chamber where effluent waters
will be filtered and let into a buffer chamber. A
pump is installed in the secondary chamber to divert
the water back to the drainage pipe or to the “biotowers”.
Vegetated Submerged Bed
The VSB design discussed here is of Variation 3),
where the VSB installation alongside the drainage
pipes serves as treatment unit for a diverted fraction
of a conduit’s load. The generic model provided in
this thesis is of pre-determined width and length to fit
a narrow stretch of sidewalk or road “shoulder” in
the EDV catchment (approximately 30 meters in
length). (Fig. 40) The beds can be covered by
interlocking grid pavements for public safety and use.
In case drains are laid in road mid section, the VSB
can be a “road island”. This installation is most
suited in low density residential areas with minor
traffic. VSB projects can be cooperation between
communities or associations. For the design of the
generic model, a fixed influent flow rate was
determined at 9-10 m3/ day (which could be a very
low fraction of the total flow rate in a conduit) for all
the possible manhole or conduit sites in EDV. The
flow rate (Q) of 9.80 m3/day is higher than the
recommended Q for an areal loading (ALR) of 20 g
TSS/ m2*day according to the EPA (2000); but is
acceptable to satisfy hydraulic requisites for safe
wastewater conductance in the VSB. The designs
were derived from the guidelines in EPA (2000);
following a model presented in Figure 40.
Fig. 40 Typical design of
VSB (EPA, 2000)
Fig. 41 “Run race
pathway” for VSB’s,
photo adapted from
website
67
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TRITA LWR MASTER
The topmost layer is composed of soil, to which
plants can start to take root and grow. A number of
macrophytes have been used in different VSB
treatment systems and pilot installations. The role of
the macrophytes in the treatment process is not clear
but the aesthetic and potential social functions it can
provide are added values for this treatment unit.
(EPA 2000)
Together, this 3-media bed functions as depth-filter
or horizontal trickling filter for the influent
wastewaters and a permeable pavement for alleviation
of rapid surface runoff in built up areas. The possible
collective effects of VSB’s to urban hydrology is not
quantified in this thesis but can be assessed in
another research study. The efficiency of 3-media
combinations is yet to be tested in EDV site. The
design details were all lifted from the manual of EPA
(2000), where the typical values with safety factors
have been provided.
The thickness or depth of the gravel bed is set at 1
meter, plus an additional depth for raising the entire
VSB to elevations at road level. The width and
length are also fixed at 0.8 – 1.0 m and 30 m
respectively. The hydraulic retention times thus vary
for each conduit site with different flow rates. EPA
(2000) provides that for Inlet zone: 40-80 mm;
Treatment zone: 20-30 mm; and for Outlet zone: 4080 mm of diameter of rock/ debris materials.
Macrophytes
Macrophytes in the VSB are included to serve more
social functions than treatment. It is not clear how
plants actually affect treatment efficiency of VSB’s
(EPA 2000).
Planting in monoculture is not
necessarily helping the treatment capacity of the beds,
and makes the VSB “susceptible to catastrophic plant
death due to predation or disease.” (George et al,
2000 in EPA 2000) It was further suggested in
Gersberg et al. (1986), Young et al. (2000) in EPA
(2000) that the “pollutant removal performance
depends and varies according to the types of wetland
plant used.” However, these findings were not
verified by other researches (EPA 2000). The
possible effects of selected macrophytes for EDVVSB are thus recommended to be studied further.
A survey of indigenous wetland plants in the
Philippines to be tested for nutrient removal in beds
includes the reputed namesake of the capital city
“Maynila”. Scyphiphora hydrophyllacea commonly called
“Nilad” in Filipino language is a wetland shrub
indigenous to Manila environment known to blossom
in local swamps in abundance. (Fig. 43) Although, no
available study has exactly identified potential roles of
this plant in nutrient removal or BOD reduction,
such plant may be further evaluated to test potential
appropriateness as a VSB system emergent plant.
But among other tested and used wetland plants for
beds, Pontedaria Cordata, L. was found to be
commercially valuable plant also capable of
phosphorus uptake in field studies in Florida.
(DeBusk et al 1995 and DeBusk et al 2001)
Fig. 42a Variation 3 VSB, 3 media installation
along drainages Cross sections of VSB
installations (top and middle) and plane view
(bottom)
Fig. 42b Prototype 3 layer media VSB
The sandy layer also provides temporary storage
space in case of water lagged top soil layers. Also, as
in depth filtration, sand surfaces provide additional
spaces for phosphorus or other chemical adsorption
or binding. As reported in the study of Brix (2001)
on media selection for constructed wetlands, the
calcareous sand media in a reed bed provided the
most effect in P removal.
This property of
calcareous sand is limited to only the first few months
of installation, and reaction spaces will be saturated
eventually. (EPA 2000) Nonetheless, the sandy layer,
which has to be contained in a “geo-textile” material
to prevent erosion to the gravel layer, still provide
several functions as buffer retention space for
excessive influent flow to the VSB, as space for
retaining waters available to soil layer on top, and for
additional space for rain fall.
68
demanding regular maintenance operations. But the
service and the benefits it potentially provides in the
long term e.g. low energy cost, minimal land use,
environmental protection and public education are
usually immeasurable. For designing such an RBC, a
“Computation procedure for RBC design” has been
provided by Metcalf and Eddy (2003). This provided
modes and guidelines to determine RBC unit
components’ dimensions, capacities and properties.
The procedure also provided limits for influent
sBOD loading as recommended by RBC
manufacturers.
This thesis mainly explores designs for EDV system
for different possible configurations. The author
cautions that the use of the formula and the resulting
values must be substantiated by experimental
research on field; so that a new formula may be
evaluated to more suitably model the designed RBC
efficacy. There are thus, 3 configurations for RBC
installations mentioned in this work.
The first RBC unit configuration is composed of 7
stages of RBC tanks and RBC shafts inline, directly
intercepting flowing wastewaters in the drain. (Fig.
44) The tanks top elevation begins at the level of the
pipe’s invert elevations. The distance between which
can be re-designed according to site specific
necessities and limitations e.g. length of available road
segment or static analysis of roads and building
structures for underground work. But generally, the
distance from one RBC tank to the next is from 1-3
meters, such that the whole length of the series of 7
RBC stages and shafts total to 16.5-28.5 meters. The
series shall follow the general slope of the drainage
line, such that the flow of the wastewater through the
units will proceed without external pumping needed.
The discs in the shaft shall come in contact with the
inflowing waters and then made to rotate by the
continuous flow of water in the drain pipe.
Theoretically, since the outlet end of the tank is of
lower elevation, the drag of the flowing water shall
turn shaft. Mechanical simulations of this set up is
not covered in this thesis, but the idea it promoted
i.e. self –supporting systems, can be relevant and can
be developed in the future. Other rotating devices
can be installed, e.g. motor drives or air diffusers.
RBC units in this kind of series and their effects in
BOD reduction was modeled using Grady (1999)
equation for estimating sBOD concentration on
succeeding shafts. An assumption of constant or
conserved sBOD-BOD ratio of 0.6 throughout the
treatment process was used. This assumption has to
be verified, as increase particulate fraction in the
influent wastewaters can prohibit more effective flux
of soluble substrate to the biofilm. (Grady et al, 1999
in Cortez et al 2008) For the first RBC configuration,
the recommended maximum first stage sBOD
loading of 15g sBOD/ m2*day was not considered.
This introduces a number of errors in the calculation,
but generally, the results illustrate optimistic effects
of treatment installations at the given sites. But due
to overloaded conditions especially in the first shaft
and first stage, problems like fouling, reduced
Fig. 43 Macrophytes for constructed wetlands:
“Pickerel Weed” Pontedaria Cordata, L., “Calla Lily”:
Zantedeschia Aethiopica, and “Nilad”: Scyphiphora
hydrophyllacea (Photo credits in the Reference List)
Other reported wetland plants to significantly
influence removal rate of nitrogen in laboratory –
scale subsurface flow wetland, include “Calla lily”
Zantedeschia Aeothiopica. (Belmont and Metcalfe, 2003)
Liu and Zhaneg (2006) has tested 6 ornamental plants
for treatment capacities in wetlands. Macrophytes
proposed to be used in the design VSB also include
low lying plants and grasses such that VSB
installations to replace sidewalk pavements, can be
modified to function as a “permeable pavement” of
interlocking grids through which the VSB
macrophytes can grow. The prototype described in
this section features a bed with 0.8 meter width. In
more spacious sidewalk locations, possibly with 1.0
meter width, the remaining 0.2 meter stretch can
accommodate taller growing macrophytes which
could provide additional aesthetic and possibly, some
community led activities.
Rotating Biological Contractors
Conventional RBC units are typically off site
treatment installations, but the principles and
dynamics of the system are taken in the proposed
designs to possibly suit an “in line” drainage
configuration. Since RBC resembles a plug-flow
reactor, with continuous inflow allowed with
continuous outflow, they can allow continuous inline
treatment process. This task proves to be challenging
for assessment and evaluation of the efficiency of the
design, as no actual experiment and laboratory scale
study has been implemented neither for this thesis
work nor for this particular kind of RBC setting. The
assessment models used in this thesis relied on the
recommendations and published analytical model of
the sBOD concentration by Grady et al (1999) to
provide theoretical functioning of the proposed and
designed RBC installations in multiple stages.
From the implementation perspective, the
underground constructions for such drainage
retrofitted RBC units can demand substantial
capitalization costs and traffic nuisance apart from
69
Trina Go Listanco
TRITA LWR MASTER
The second RBC configuration is one that would
follow the assumption of a fixed sBOD/BOD ratio
of 0.6, and the 15 g/ m2*day maximum sBOD
loading for the first shaft, as recommended. To
somehow meet this sBOD loading criteria a “parallel
and tapered” system is used to distribute the influent
wastewater along a parallel series to avoid
overloading and fouling of the first of the series of
shafts. This “longitudinal” parallel configuration
features a way for the influent high loading
wastewater to be distributed in an array of shafts,
working independent and simultaneously or parallel
each other, such that one array functions as one
stage. Along the drains, the RBC shafts are installed
not exactly intercepting the drain, but along side them
in a longitudinal parallel distribution. For the
succeeding stages, the number may be decreased
following a tapered RBC system. This way, the RBC
shaft receives diverted flow or filtered effluent and
the influent water is made to flow in a horizontal
plank, of zero percent slope, and made to rise up to
0.1m height by a weir. Then the water is made to
overflow into the RBC tank with the shaft and discs.
The shafts and the discs are rotating perpendicular to
the inflow and the layout for configuration 2 is
provided in Appendix XI- Drawings.
Design Prototype for RBC shafts and stages
The shafts are very crucial components of the RBC
system. Noted failures of the RBC units usually
involve breaking of shafts due under-design or
unexpectedly heavy load from biofilm growth. It is
thus, important that shafts are kept small and built
sturdy.
The RBC shafts can be turned in a variety of ways, by
a variety of mechanisms. One ideal option, like in the
first configuration, is to make the influent waters turn
the panels and the discs themselves as it continues to
flow through the tank. This way, the RBC units will
be close to self supporting systems. But for increased
reliability of RBC treatment, conventional designs
involving externally powered motors can be more
useful. An air diffuser system is another driving
option for turning the RBC shafts. Additional air
cups on discs are usually mounted to ensure the
rotation of the shaft at controlled rates (Metcalf and
Eddy 2003). The introduced air can increase oxygen
transfer and increase dissolved oxygen (DO) in the
tanks. An example of an “air driven” RBC is
presented in Figure 49.
This thesis mentions three possible shaft driving
systems, but considers at this point, that an air-driven
system in selected RBC shafts is most cost effective
to use as shaft driver mechanism and aeration unit.
The study of Surampalli and Baumann (1996),
confirms the overall advantages of providing
supplemental aeration to overloaded RBC stages,
specifically for a high BOD loading application such
as a combined municipal and industrial dairy
wastewaters.
treatment efficiency is probable. This configuration
can be adapted for post denitrification as overloaded
first stage turn anaerobic. Thus, configuration 1 may
be applied for recycling effluents. Post denitrification
inline RBC configuration is not pursued further in
this thesis. The “inline” RBC designed herein are not
configured for possible recycling, because of
additional pumping required.
Further, this configuration must be further evaluated
in an experiment, to verify the validity of the results
using the Grady et al. (1999) function; and to correct
values affecting treatment system efficiency of
overloaded first stage and first shaft. A more
appropriate model can be developed to analyze
dynamics in the RBC treatment process of this kind.
The net effect of RBC shafts installations in the
upstream conduits, with the first configuration is
substantial dilution of influent wastewaters. Each
installation is composed of 7 shafts, with fixed
surface area of 1800m2. The shaft design was
estimated using the diameter of the pipes, such that
the RBC tanks and the mounted discs’ radius atop the
tanks need not exceed the top elevation of the
drainage pipe. (Fig. 45)
The results are presented in Table 20a and 20b and
they show substantial reduction of sBOD in the
effluent waters after the 7th shafts. This theoretical
performance reflects the behavior of the function,
but is not likely to be realistic. The results should
therefore be tested in actual pilot-studies. Also, note
that the results in this calculation are with overloaded
first stages and must be re modeled using a more
appropriate function. Known ways to address
overloading of shafts include “step-feed”
configurations, tapered distribution or supplemental
aeration system. The “step feed” system has been
described in Metcalf and Eddy (2003) as in Figure.
46. A tapered distribution means a decreasing
number of shafts or tanks in the succeeding stages of
the RBC treatment train. But similar in aim of
distributing loads, 2 parallel distribution arrangements
(longitudinal and lateral) are proposed and mentioned
for the inline treatment.(Fig. 47) The parallel
distribution system requires less flow control
mechanism to be operated, unlike a “step-feed”
system. These “solutions” are included in the next
proposed RBC configurations.
Configuration 1) with overloaded shafts and discs
may be supplemented with aeration systems that can
turn shafts while allowing faster oxygen transfer to
the influent wastewaters. The aeration system design
has not been detailed in this thesis but the theoretical
oxygen requirements to treat 1 kg BOD have been
used. According to EPA (2000), 1.5 kg of oxygen is
required to treat 1 kg of BOD such that the BOD
load in g/day in each selected site or tank can be
assumed to demand a certain amount of oxygen
(g/day). Table 20a and 20b provide the influenteffluent BOD characteristics in 7 stages of RBC tank
for some selected sites.(See full table in Appendix III)
70
Fig. 44 Image of RBC first
configuration, with 7 RBC
units in series, image not
drawn to scale, 3D Max
Studio
rendering
by
Martin Varga
Fig. 45 Prototype design for
RBC installations, Configuration 1. 3D Studio Max
rendering for this thesis by
Martin Varga
Fig. 46 Diagram of “stepfeed” RBC distribution,
lifted from Metcalf and Eddy
(2003)
Primary effluent
FLOW
Fig. 47 - 48 “Longitudinal Parallel” distribution (left) along the drains, Configuration 2) and “Lateral parallel”
distribution (right)
71
Trina Go Listanco
TRITA LWR MASTER
Table 20a. Summary of Configuration 1 RBC Performance in DRY Weather (Full Table in Appendix III)
2025 RBC Configuration 1
Stage 1
sBOD/ BOD ratio = 0.6
Surface area per shaft = 1800m
DRY
Weather
Manhole
Id
Flow rate
[m3/s]
Stage 2
Stage 7
2
Flow
rate
[m3/da
y]
Daily
BOD prod
[g/day]
BOD
conc.
[mg/L]
In
sBOD
[g/m3
]
Out
sBOD
[g/m3
]
E-BOD
[g/m3]
Organic
loading [g
BOD/m2*d]
In
sBOD
[g/m3
]
Out
sBOD
[g/m3]
E-BOD
[g/m3]
Organic
loading [g
BOD/m2*
d]
In sBOD
[g/m3]
Out
sBOD
[g/m3]
E-BOD
[g/m3]
Organic loading
[g BOD/m2*d]
101
0.010753
929.1
436236.3
469.53
281.7
98.5
164.2
84.76
98.5
50.5
84.1
43.4
13.5
11.1
18.5
9.6
114
0.036331
3139.0
1358150
299.19
179.5
110.9
184.8
322.22
110.9
77.4
129.0
225.0
32.4
28.0
46.6
81.3
Outfall02
0.003677
317.7
200046.4
629.65
377.8
74.2
123.6
21.82
74.2
28.7
47.8
8.4
5.5
4.4
7.4
1.3
Outfall05
0.015116
1306.0
360160.8
275.78
165.5
79.9
133.1
96.57
79.9
48.4
80.7
58.5
16.2
13.7
22.8
16.6
Outfall09
0.044796
3870.4
1145734
296.02
177.6
116.3
193.9
416.87
116.3
84.2
140.3
301.8
37.5
32.6
54.4
117.0
Outfall06
0.024987
2158.9
647454.4
299.90
179.9
99.5
165.9
198.93
99.5
65.1
108.5
130.1
24.5
20.9
34.9
41.8
Outfall07
0.013419
1159.4
338358.6
291.83
175.1
79.5
132.5
85.36
79.5
46.6
77.7
50.1
14.9
12.5
20.9
13.5
Outfall08
0.019085
1648.9
296880.4
180.05
108.0
64.2
107.0
98.02
64.2
43.8
73.0
66.9
17.6
15.2
25.3
23.2
Organic
loading [g
BOD/m2*d]
In
sBOD
[g/m3
]
Out
sBO
D
[g/m3
]
Organic
loading [g
BOD/m2*
d]
In sBOD
[g/m3]
Table 20b Summary of Configuration 1 RBC Performance in WET Weather (Full Table in Appendix III )
WET
WeatherFl
ow
rate
[m3/s]
Flow
rate
[m3/da
y]
BOD
conc.
[mg/L]
In
sBOD
[g/m3
]
Out
sBOD
[g/m3
]
Daily
BOD prod
[g/day]
101
0.02940
2540.2
436236
171.730
103.0
69.60
116.00
163.71
69.60
51.38
85.64
120.85
23.68
20.72
34.53
48.74
114
0.10120
8744.3
1358150
115.461
69.28
61.66
102.76
499.20
61.66
55.48
92.47
449.23
39.39
36.69
61.16
297.09
Outfall02
0.01045
903.66
200046
221.373
132.8
60.89
101.48
50.95
60.89
35.89
59.82
30.03
11.57
9.73
16.21
8.14
Outfall05
0.02903
2508.1
360160
143.594
86.16
60.54
100.90
140.59
60.54
45.85
76.41
106.47
22.16
19.50
32.50
45.28
Outfall09
0.10100
8726.9
1145734
131.287
78.77
69.16
115.27
558.87
69.16
61.55
102.59
497.37
42.43
39.32
65.54
317.74
Outfall06
0.03877
3350.1
647454
193.262
115.9
81.34
135.56
252.30
81.34
61.53
102.54
190.85
29.67
26.10
43.50
80.97
Outfall07
0.01974
1706.0
338358
198.326
119.0
69.44
115.74
109.70
69.44
46.87
78.11
74.04
18.53
15.92
26.54
25.15
Outfall08
0.03656
3159.2
296880
93.9722
56.38
45.10
75.16
131.92
45.10
37.35
62.26
109.27
21.67
19.55
32.58
57.19
Manhole
Id
E-BOD
[g/m3]
72
E-BOD
[g/m3]
Out
sBOD
[g/m3]
E-BOD
[g/m3]
Organic
loading
[g
BOD/m2*d]
.
the dimensions for this “longitudinal parallel” RBC
are made to fit the space under the EDV roads.
Access to the RBC installations can be done through
designed manholes. In case of drainage lines built in
the mid-section of the road, the whole drainage
segment with designed RBC shall be moved to one
side of the road to provide space for the RBC tanks.
The maximum width of the installation is 6 meters
and the average standard width of EDV roads are
approximately 7 meters. The other side of the road
where RBC tanks and shafts are installed will have to
be provided for with a small diversion pipe to convey
wastewaters to the next conduit further downstream.
The results for simulated loading and removal figures
of this RBC configuration are presented in Table 24.
Note that the highlighted values are overloaded
stages and thus would require supplemental aeration
systems. In “parallel-distribution” configurations,
treatment by-pass procedures can not be done
separately for each RBC shaft and tanks. By-pass
treatment is done by closing sluices or gates to the
horizontal distributing plank such that the whole
RBC unit process is skipped in events of excessive
rain or flow rate.
A brief evaluation of the mentioned RBC
configuration 2) with “longitudinal parallel
distribution” series is summarized in Table 21. All
designs considered are for until year 2025, dry
weather and the projected population is around
300,000 by 2025.
Fig. 49 “Air driven RBC” Diagram lifted from:
http://ragsdaleassociates.com/WastewaterSystemsCe
rtificationStudyGuide/07Fixed%20Media.pdf
Configuration 2) would involve several treatment
stages. After the wastewaters have been turned in the
first stage, the effluent wastewater is channeled to a
second or third stage and then into the post-RBC
filter-chambers. The effluent will then be pumped
and discharged back into the drain pipe or to a
“biotower” treatment unit. The number of tanks or
shafts for each stage is fixed to theoretically achieve
desired BOD concentrations of the effluent at 30g
BOD/ m3 or sBOD of 15 g/m3. The ideal number
of shafts in the first stage is set to a maximum of 15
to achieve possibly the maximum loading of 15g
sBOD/m2*day. This number of shaft is may prove
to be challenging to build and maintain. It would
require much underground works and space beyond
the standard road widths in EDV.
Initial results show lesser shafts are needed for the
succeeding stages. And so for maximum 15 shafts in
the first stage, a maximum of 2 and 3 stages were
considered. Table 22 and 23 summarize theoretical
sBOD reduction performance of these RBC
configurations with 15 first stage shafts and with
maximum 2 and 3 stages.
Note that the total number of shafts required for
both cases would be at least 300 tanks and stages
which demand significant amount of maintenance
and capital costs. Thus, another overloaded RBC
series is proposed. An RBC with longitudinal-parallel
distribution, with maximum 7 shafts in the first stage
and maximum 3 stages has been designed. The last 2
stages are made to have maximum 2 shafts each so
that the entire unit fits the width of the road and 1
continuous conduit. The overloaded stages are also
designed to have supplemental aeration systems to
compensate the demand for higher oxygen.
The optimal designed RBC installation is thus, with
7-2-2 shafts for the first, second and third stages.
Other designs for smaller sites e.g. 7-2-0, 4-2-2 and 22-2 are also presented in Appendix XI-Drawings. All
Table 21 Summary of RBC configurations
RBC series
Max 2 stages,
max 15 shafts
Max 3 stages,
max 15 shafts
Total
number of
shafts
required,
number of
people
served
376: 797
people per
RBC shaft
449: 669
people per
RBC shaft
Max 3 stages,
max 7 shafts
(7-2-2 series)
(Except for
installations
along Visayas
St, Main
Drainage with
8 maximum
shafts in the
first 2 stages)
73
296: 1014
people per
RBC shaft
Remarks
Too lengthy, not
cost-efficient,
more efficient in
reducing BOD,
but will still
require
“biotowers” for
nitrification
Ideal with
necessary
aeration, slightly
larger biotowers
required for
combined BOD
removal and
nitrification;
least demand
for construction,
maintenance
and operation
Trina Go Listanco
TRITA LWR MASTER
Table 22. Theoretical results for Configuration 2, Maximum 2 stages-maximum 15 shafts at 1st stage, DRY and WET
weather 2025 (Full Table in Appendix V)
sBOD load
at Stage 1
[g/m2*day]
Num of
Shafts
at
Stage
1
sBOD load
at Stage 2
[g/m2*day]
DRY
Flow
rate
[m3/d]
Num
of
Shafts
at
stage
2
Effluent
BOD
Conc
[g/m3]
Manhole
Original daily
load, mBOD
[g/day]
Shaft's
inflow load
[g/day]
Outfall02
200,046
200,046
318
13.34
5
6.22
1
29.6
11
949,785
949,785
4,291
21.11
15
15.53
6
40.7
8
1,521,357
746,403
6,023
16.59
15
17.50
6
37.5
NL 48
Outfall05
360,161
360,161
1,306
15.01
8
12.65
2
36.6
Outfall09
1,145,734
1,145,734
3,870
25.46
15
15.87
6
43.3
Outfall06
647,454
647,454
2,159
15.42
14
14.24
3
38.1
Outfall07
338,359
338,359
1,159
14.10
8
10.99
2
34.9
Outfall08
296,880
296,880
1,649
14.14
7
14.64
2
36.4
181
477,251
477,251
1,116
15.91
10
11.58
2
36.8
251
698,133
261,918
1,866
14.55
6
15.96
2
36.4
94
2,367,273
498,590
7,342
11.08
15
18.39
5
30.8
44
5,719,664
2,324,585
15,143
51.66
15
83.32
5
67.0
Manhole
Original daily
load, mBOD
[g/day]
Shaft's
inflow load
[g/day]
Outfall02
200,046
200,046
NL 53
DM10
Wet 2025
WET
Flow
rate
[m3/d]
sBOD load
at Stage 1
[g/m2*day]
Shafts
at
Stage
1
904
13.34
5
sBOD load
at Stage 2
[g/m2*day]
Shafts
at
stage
2
Effluent
BOD
3.23
1
53.7
NL 48
11
949,785
949,785
6,782
21.11
15
8.89
6
59.0
8
1,521,357
858,680
9,853
19.08
15
10.70
6
48.9
Outfall05
360,161
360,161
2,508
15.01
8
5.45
2
52.2
Outfall09
1,145,734
1,145,734
8,727
25.46
15
12.01
6
61.9
Outfall06
647,454
647,454
3,350
15.42
14
4.46
3
55.9
Outfall07
338,359
338,359
1,706
14.10
8
3.84
2
54.1
Outfall08
296,880
296,880
3,159
14.14
7
6.86
2
45.6
181
477,251
477,251
2,849
15.91
10
5.24
2
55.2
251
698,133
340,800
4,794
18.93
6
11.92
2
44.7
NL 53
DM 10
94
2,367,273
717,422
18,336
15.94
15
12.59
5
30.9
44
5,719,664
2,735,219
39,024
60.78
15
49.40
5
57.0
74
Table 23. Results for Configuration 2, Maximum 3 stages-maximum 15 shafts at 1st stage, DRY and WET weather year 2025 (Full Table in Appendix VI )
DRY
Inflow
conc
Flow
rate
[m3/d]
to
the
1st shaft
[g/m3]
Manhole
Original
daily
load,
mBOD
[g/day]
Shaft's
inflow load
[g/day]
Outfall02
200,046
200,046
318
Outfall05
360,161
360,161
1,306
Outfall09
1,145,734
1,145,734
Outfall06
647,454
Outfall07
Outfall08
sBOD
load at Stage
1 [g/m2*day]
Num of
Shafts at
Stage 1
629.7
13.34
275.8
15.01
3,870
296.0
647,454
2,159
338,359
338,359
296,880
94
44
sBOD
load at Stage
2 [g/m2*day]
Num of
Shafts at
stage 2
5
6.22
8
12.65
25.46
15
299.9
15.42
1,159
291.8
296,880
1,649
2,367,273
474,416
5,719,664
2,262,923
Manhole
Original
daily
load,
mBOD
[g/day]
Shaft's
inflow load
[g/day]
Outfall02
200,046
200,046
sBOD
load at Stage
2 [g/m2*day]
Num of
Shafts at
stage 3
Effluent
BOD after
final stage
BOD
after 2nd
Stage
BOD after
1st Stage
1
3.14
1
18.4
29.6
58.7
2
7.96
2
25.8
36.6
58.1
15.87
6
9.31
6
29.3
43.3
73.8
14
14.24
3
13.72
2
29.6
38.1
59.4
14.10
8
10.99
2
13.47
1
27.8
34.9
56.9
180.0
14.14
7
14.64
2
10.00
2
27.1
36.4
53.3
7,342
64.6
10.54
15
17.77
5
14.63
5
25.3
29.9
36.3
15,143
149.4
50.29
15
81.80
5
66.56
5
55.3
65.9
81.0
Inflow
conc to
shaft
[g/m3]
sBOD load at
Stage
1
[g/m2*day]
Shafts at
Stage 1
sBOD load at
Stage
2
[g/m2*day]
Shafts at
stage 2
sBOD load at
Stage
2
[g/m2*day]
Shafts at
stage 2
BOD
after 2nd
Stage
BOD after
1st Stage
904
221.4
13.34
5
3.23
1
2.25
1
28.2
37.4
53.7
DM10
Wet
WET
Flow
rate
[m3/d]
Effluent
BOD
Outfall05
360,161
360,161
2,508
143.6
15.01
8
5.45
2
4.10
2
31.1
39.3
52.2
Outfall09
1,145,734
1,145,734
8,727
131.3
25.46
15
12.01
6
8.99
6
36.7
46.4
61.9
Outfall06
647,454
647,454
3,350
193.3
15.42
14
4.46
3
3.23
2
33.4
40.5
55.9
Outfall07
338,359
338,359
1,706
198.3
14.10
8
3.84
2
2.64
1
31.1
37.1
54.1
Outfall08
296,880
296,880
3,159
94.0
14.14
7
6.86
2
5.51
2
30.5
36.6
45.6
94
2,367,273
878,203
18,336
47.9
19.52
15
14.86
5
13.56
5
30.6
33.3
36.5
44
5,719,664
2,832,778
39,024
72.6
62.95
15
50.88
5
47.39
5
51.1
54.6
58.7
DM 10
75
Trina Go Listanco
TRITA LWR MASTER
In Outfall 09, the theoretical effluent concentration with the DRY weather 2025 design is slightly above the prescribed limit (56 g/m3). Its lateral lacks detailed profile such that
upstream installation design was not possible. Upstream installation along this lateral can possibly reduce the effluent concentration in the outfall. In general, further studies on the
drainage profile would allow designing more installations upstream in more appropriate sites. Also, for DM10 installations, 8 shafts in the first and second stage can fit the width of
the road, such that the series is 8-8-3. The construction of this RBC series is special since DM10 has 2, 2m X 2m conduits. It is possible that for each of the existing conduit, an 88-3 RBC is put up.
Table 24. Theoretical results of 7-2-2 RBC series, all concentrations in g/m3. (Full table in Appendix VII)
Manhole
Original
daily
load,
mBOD
[kg/day]
Shaft's
inflow
load
[kg/day]
DRY
Flow
rate
[m3/d]
Inflow
conc to
the 1st
shaft
[g/m3]
Remaining
mBOD
[kg/day]
Removed
BOD
[kg/day]
load at
Stage 1
[g/m2*day]
Shafts
at
Stage 1
sBOD
sBOD
load at
Stage 2
[g/m2*day]
sBOD
Shafts
at
stage 2
load at
Stage 3
[g/m2*day]
Shafts
at
stage
3
Final
Effluent
BOD
Conc
BOD
Conc
after
2ndStg
BOD
Conc
after
1st
Stg
114
1,358
0.94
3,139
301.0
154
790
44.98
7
49.15
2
34.18
2
49.1
65.3
93.9
205
950
0.15
3,525
43.8
84
69
7.35
7
16.29
2
284.64
0
24.1
24.2
27.7
177
549
0.46
979
470.5
24
435
21.93
7
11.86
2
6.42
2
25.5
39.4
72.7
77
189
0.18
908
209.2
19
170
15.83
4
8.66
2
4.94
2
21.7
32.6
57.3
Outfall02
200
0.2
318
629.7
6
193
9.53
7
2.65
2
22.19
0
19.7
20.9
50.0
8
1,521
0.79
6,023
132.5
301
496
38.00
7
71.23
2
59.08
2
50.1
58.9
71.0
Outfall05
360
0.36
1,306
275.8
34
325
17.15
7
13.41
2
8.31
2
26.7
38.2
61.6
Outfall09
1,145
1.1
3,870
296.0
215
930
54.56
7
65.28
2
46.81
2
55.7
72.6
101.2
Outfall06
647
0.64
2,159
299.9
831
564
30.83
7
28.87
2
19.05
2
38.5
52.9
80.2
Outfall07
338
0.33
1,159
291.8
290
309
16.11
7
11.67
2
7.03
2
25.0
36.4
60.4
Outfall08
296
0.29
1,649
180.0
446
252
14.14
7
14.64
2
10.00
2
27.1
36.4
53.3
251
698
0.25
1,866
134.7
49
202
11.97
7
14.65
2
10.59
2
26.3
34.0
47.1
230
2,641
0.75
8,956
84.2
413
341
35.92
7
85.48
2
76.32
2
46.1
51.1
57.3
76
The third RBC configuration in this thesis has also
cautiously considered the maximum sBOD loading of
15g sBOD/m2*day in the first stage or first shaft. It
features the shafts spread across perpendicularly to
the wastewater flow and to the drainage pipes. (Fig.
48)The influent wastewaters will be diverted for
maximum 15 RBC shafts in the first stage for
simultaneous treatment. But since 15 RBC tanks
would translate to minimum 30 meters of width, this
configuration is may not be very viable in a very
dense residential area, with narrow roads, like EDV.
Although, this configuration would not disrupt the
drainage connections of many households along the
drains, this will require displacement of several
structures across the roads. It also presents high risks
in case of excessive flow rates. Thus, this thesis
focuses on the design of the “step-feed” longitudinal
RBC installation with 7-2-2 maximum shafts for 3
stages.
The model used for evaluating the design of all
mentioned RBC configurations is provided by the
equation:
Sn =
− 1 + 1 + (4)(0.00974( As / Q) S n −1
(2)(0.00974)( As / Q)
Fig. 50 Draft of shaft and disc shapes used for RBC
design calculations
Where S n = sBOD concentration in stage n (g/ m3)
As = disk surface area n
The bottom of the tank has to slope gently to the
next corridor and should allow water to flow into the
next stages. For maintenance, a manhole must be
constructed for each of the RBC tank.
Three shaft rotation driving systems are briefly
mentioned in this thesis. The details of each driving
system are not provided in this work, but any can be
adapted for the RBC tank design. For supplemental
aeration system, at least 2 rows of diffusers are
proposed to be mounted beneath the shafts.
Although, air diffusers can demand more
maintenance and energy, it can keep particles in
suspension that could possibly contribute to more
effective aerobic degradation and improve
sedimentation at the bottom.
Power sources:
Although the original idea for the inline RBC designs
was for flowing water to drive the discs, the proposed
design can be externally powered. Each shaft shall be
connected to an electrically rotor. But to insist on
employing self-supporting principles in the design to
enhance criteria of “sustainability” of the proposed
wastewater treatment system, a renewable power
source of medium scale, e.g. wind turbine, can be
explored to power RBC rotations and “biotower”
pumps. The details of this component are beyond
the scope of this thesis, but such concept can be
employed to decrease energy costs of operating the
proposed treatment system in the long run.
(m2)
Q = flowrate (m3/day)
(Grady et al 1999 in Metcalf and Eddy 2003, p. 937)
Standard Shafts and Discs
One shaft in this thesis is meant to be a standard
design of 2 meters long. The design is derived from
published characteristics of standard discs and shafts,
although most of the reviewed RBC installations have
shafts of longer lengths, 5-10 meters. The design of
the shaft in this thesis supports perforated bladeplanes (parallel to the wastewater flow direction) and
cross disc panels across the entire shaft (with folds/
corrugations). The discs’ design is made of light
plastic material. The diameter of the disc is kept at 2
meters, such that the center of the shaft is at the level
of the invert elevation of the drainage pipe, making 1
meter radius fitted in a tank. The resulting surface
area is estimated to be 1800 m2 on which biofilm can
grow. This area was used for calculations. This
surface area was used as a constant and standard
value for each RBC shaft/ unit. There are other
existing designs such as packed shafts, discs with
foams among many others as mentioned in Cortez et
al (2008), but for simplification of design calculation,
a “standard density” disc media was used.
The entrance to the tank has to have a dike or weir
that would cause water to rise and drop at higher
velocities into the tank.
77
Trina Go Listanco
TRITA LWR MASTER
Rotational Speed:
The turning of the RBC shaft is set at 2 revolutions
per minute which is within the recommended
guideline for RBC discs with 1-4 meter diameters;
and for RBC shafts with 5-10 m length, according to
Mathure and Patwardhan (2005) in Cortez et al
(2008). Pilot study for EDV RBC will yield more
exact optimum rotation speeds, to achieve advantages
of efficient oxygen transfer, without stripping the
biofilm.
Tankage and Hydraulic retention times
The “tank” is actually a basin dug below the invert
elevation of the drainage pipe, at a level to
accommodate the RBC shaft blades and discs. Its
dimensions shall also allow some sediment to settle at
the bottom. The tanks are assessed to allow
hydraulic retention times depending on the flow
rates. The range is from least 0.7 hours for each of
the RBC units, before the wastewater are to flow
downstream through the outlet side.
Solids
accumulated at the tank bottom can be collected at
the lower corner of the tank by manual collection.
Although longer retention times would yield better
distribution of substrate and effective removal of
constituents in influent wastewaters, it would cost
more energy. (Hanhan et al 2005, Najafpour et al
2006 in Cortez et al 2008) “Full scale RBC’s have the
advantage of requiring short hydraulic retention
periods, (generally less than 1 hour)”. (Benefield and
Randall 1980 in Cortez et al 2008)
The resulting retention times for RBC units (with
different flow rates) in selected manholes are as
follows: Note that the designed prototype has a fixed
effective volume of 6.3m3.
Staging
The number of stages has been limited in the design
to fit a drainage segment or conduit between 2
manholes. Assuming that the distance between 2
manholes are approximately 25-30 meters, RBC
installations must be within those lengths. Longer
installations would translate to longer diversion pipes
for households and pipe connections along the remodeled treatment segment. The width of the design
has also been limited to the width of 2-way roads in
EDV, at approximately 7-8 meters. And only 3
stages can be accommodated in such limited space.
Nitrifcation could have been achieved with more
stages in the RBC installation, but the existing road
and drainage infrastructure makes it difficult to
establish and add 2 more RBC stages to the proposed
prototypes.
The graph of BOD and sBOD reduction in the
Configuration 1) (Manhole 101) shows marginal
decrease in BOD removal after the 7th stage. (Fig.
51) The function used to model the removal
demonstrates the possible effects of oxygen
limitations or substrate limitation in several stages.
Configuration 1) allows more than 15g/m2*day of
sBOD load in the first stage and the sBOD values are
not necessarily true.
Table 25. Retention times in each stage of the
designed RBC series (7-2-2) configuration with tank
volume of 6.3 m3
Retention
Retention
Retention
time - 1st time - 2nd time - 3rd
stage [hr]
stage [hr]
stage [hr]
Manhole
NL 50
101
1,139
0,325
0,325
114
0,337
0,096
0,096
253
5,971
1,706
0,085
171
0,824
0,236
0,236
39
0,374
0,187
0,187
71
0,308
0,088
0,088
205
0,300
0,086
0,004
200
3,775
3,775
3,775
177
1,081
0,309
0,309
77
0,666
0,333
0,333
60
0,283
0,081
0,081
3,331
0,952
0,048
11
0,247
0,070
0,070
8
0,176
0,050
0,050
Outfall05
0,810
0,232
0,232
Outfall09
0,273
0,078
0,078
Outfall06
0,490
0,140
0,140
Outfall07
0,913
0,261
0,261
Outfall08
0,642
0,183
0,183
181
0,948
0,271
0,271
251
0,567
0,162
0,162
263
0,344
0,098
0,098
227
0,254
0,073
0,073
40
0,140
0,040
0,040
230
0,118
0,034
0,034
94
0,165
0,165
0,062
44
0,080
0,080
0,030
NL 51
NL 49
Outfall02
NL 48
NL 53
NL 54
DM 10
78
The hydraulic and the organic loading differ at each
manhole site. In RBC Configuration 1), the first stage
and first shaft are definitely loaded with more than
the recommended 15 g/m2*day of sBOD limit. The
adaptation of the 1st configuration will entail less
capital cost but would demand additional pre
treatment methods e.g. supplemental aeration for
effective functioning.
In several studies it has been found out that “as the
applied organic rate increases, the substrate removal
rate increase and removal efficiency decreases.”
(Cortez et al 2008) Thus, the second configuration,
which allows more oxygen transfer to the RBC
reactors, will likely to prevent dissolved oxygen
limitation that could cause reduction of removal
efficiency in the succeeding stages. This will also
prevent nuisance associated with anaerobic
conditions.
For the second configuration and third configuration,
the first stage organic loading is kept at maximum 15
g sBOD/m2*day or close to that. However, the
major setback of configuration 2) is the huge area it
would require. A more realistic design fit for EDV
roads would require limited surface area per stage.
The optimum RBC configuration is one with 7-2-2
shafts in terms of staging and loading.
The
installation of the 7-2-2 series fit a conduit between 2
manholes and the width of the standard road.
Although the some of the stages in the 7-2-2 series
are “overloaded”, supplemental aeration in the tanks
can be used to alleviate the probability of fouling, and
reduced efficiency due to overloaded discs in these
stages. The same supplemental air diffuser is also
chosen to be the driver for the disc rotation. The
resultant organic loading for each shaft in 7-2-2 RBC
series shafts in 3 stages are provided in Table.24.
Decrease in Effluent sBOD "Out sBOD [g/m3]"
Manhole 101 from 1st-7th RBC stage
(DRY conditions, 2025)
Out sBOD [g/m3]
sBOD concentration (g/m3)
120.0
100.0
80.0
60.0
40.0
20.0
0.0
Shaft 1
Shaft 2
Shaft 3
Shaft 4
Shaft 5
Shaft 6
Shaft 7
Stages
Fig. 51 Graph of marginal decrease of effluent sBOD
in 7 stages using the Grady (1999) function. (Manhole
101, at DRY weather conditions for 2025)
The second RBC configuration with maximum 15
shafts on the 1st stage and with 2 -3 stages has a total
length of at least 40 meters while configuration 2)
with 7-2-2 series, would require 30 meters. The
numbers of shafts for each stage in configuration 2)
are mentioned in the Tables 22-24. The third RBC
configuration type would require shorter lengths but
increased widths as the shafts are distributed laterally
across the drain.
Some manholes with very high concentrations of
BOD, the RBC unit may have to add 2 or more
stages with each stage having more than 1 shaft.
Although last-stage effluent recirculation has been
reported to “increase RBC activity” (Ayoub and
Saikaly 2004 in Cortez et al 2008), recirculation
process along the drainage lines is apparently only
operable in dry weather. The additional provisions
for such recirculation may not be cost efficient for an
“inline” RBC set up.
Loading
Organic loading is expressed as the product of flow
rate and the sBOD concentration divided by the
surface area of the shaft in g sBOD/m2*day. And
the hydraulic loading is the quotient of the flow rate
and total surface area in m3/m2*day.
“Biotowers”
The “biotower” installations are proposed to treat
further the effluents of the RBC where the influent
BOD concentration has been reduced to allow
nitrification. Although RBC units can be designed to
have “combined BOD5 and NH4- N removal
functions, such require a minimum of 4 stages of
treatment”. (Cortes et al 2008)
Fig. 52 Configuration 1)
staging across the drainage
pipe
79
Trina Go Listanco
TRITA LWR MASTER
The resulting volume provides the dimension needed
for containing the entire packing for the “biotower”.
Since a standard packing depth of 6.1 meters was
assumed for this thesis, the filter area of the
“biotower” is determined by: (Metcalf and Eddy,
2003)
Four stage RBC units in an “inline” configuration
setting translate to lengthier installations, which is
theoretically possible but rather impractical.
Nitrification process can be introduced post-RBC,
when organic concentration has been reduced
considerably to make nitrifying bacteria compete
better with other bacteria.
The design components for the “biotower” units in
this thesis are made to be capable of 90% TKN
removal. Depending on the RBC configuration and
their estimated effluent BOD concentration,
differently sized “biotower” designs apply. The
different “biotower” filter area requirements for
different RBC configuration is presented in Tables 27
and 28.
The design procedure was lifted from Metcalf and
Eddy (2003), with each installation having a plastic
packing media standard for 6.1 meters (height), with
assumed packing coefficient value of 0.5.27
For the design, a required minimum wetting rate of
0.5 L/m2*sec was used. All standard measures and
properties published for this media type was provided
in Metcalf and Eddy (2003), including the following
design formula.
The nitrification rate Rn was identified for each
selected manhole or conduit sites by: (Metcalf and
Eddy 2003)
⎛ BOD ⎞
Rn = 0.82⎜
⎟
⎝ TKN ⎠
FilterArea =
The Hydraulic application rate q is determined by:
q=
Loading based on volume: (Metcalf and Eddy 2003)
BODLoading =
−0.44
VOR =
[S o + 4.6( NO x ]Q
Volume
The entire calculation was done in MathCad program
and is presented in Appendix XII. The results are
summarized in Appendix VIII which includes the
filter area required for each chosen manhole- conduit
site to achieve 90% TKN removal for RBC
configurations 2) maximum 15 shafts and 2 and 3
stages. For RBC 7-2-2 configuration, the resulting
“biotower” design is summarized in Appendix IX.
All the above calculations assumed a TKN daily
production per capita of 3 gTKN/ person *day. This
number was reviewed to be lower than realistic
figures. And so for the recommended higher TKN
value of 7.5 gTKN/ person*day, the resulting
“biotower” design is also presented in Appendix IX.
Note that the BOD effluent concentrations in these
calculations are theoretical values. In reality, such
small fractions of BOD can not be expected.
For different configurations and staging in the RBC
unit, there are consequent differences in the designs
for “biotower”. The optimal combination for RBC“biotower” configuration is one which requires the
least land area for the “biotower” units, such that not
so much land have to be acquired. With the range of
filter area required in this design proposal, one
biotower installation could mean relocation of 1-4
households. And since the installation is highly
The surface area of packing to achieve the set goal of
90% TKN removal was calculated by: (Metcalf and
Eddy 2003)
TKNremoval
Rn
The volume of the packing material is determined by
assuming the packing property of having specific
surface area of 100 m2/ m3. (Metcalf and Eddy
2003)
27
(Q )( BODconcentration)
volume
The volumetric oxidation rate for each designed
“biotower” is determined by (Metcalf and Eddy
2003)
TKNremoval = 0.90(Q )(InfluentTKNConcentration )
Volume =
Q
FilterArea
Further, the BOD loading for each designed
“biotower” is determined by: (Metcalf and Eddy
2008)
The TKN removal was then calculated to give the
amount of TKN targeted / aimed to be removed per
day. (Metcalf and Eddy 2003)
As =
volume
depth
packingsur facearea
specificsu rfacearea
Provided value in Metcalf and Eddy (2003)
80
aggregate and discharge wastewaters are: 193 (outfall
of DM 10) and 225 (combined outfall of NL 053 and
54). These outfalls have several upstream installations
but the estimated BOD load reduction of them is
presented in Table 26.
Table 26 provides options and the possible
“theoretical” performance of the proposed treatment
system. In case of phased development and only the
RBC units are to be installed and financed initially,
the treatment might slightly fail in achieving the set
standard for BOD. On optimistic note, since the
design has purposively overestimated a percent on
populations and BOD production per capita, the
effluent at the major outfalls might still comply with
the standards. If the proposed combined storm and
wastewater treatment system performs daily
monitoring of effluent concentrations, it is allowed
10th percentile of exceeding the maximum limits, and
can possibly pass the standards.
The dry weather designed “biotower” is theoretically
for 90% TKN removal, but its operation during
average wet weather conditions would translate to
about 50% removal in most “biotowers”.
From evaluation of results, it is apparently more costeffective to build the designs for DRY weather- 2025,
before the system can be upgraded for WET weather
conditions until 2025. A short comparison of the
“biotower” filter area requirements for dry and wet
weather for different RBC configurations is presented
in Table 28.
visible, the design implementation should entail more
thorough and comprehensive assessment and
negotiation of installations with the stakeholders.
This assessment and negotiation processes are
beyond the scope of this thesis.
Note that the guideline for trickling filter flushing and
normal dosing rates for known BOD loading
(kg/m3*day) were provided in Metcalf and Eddy
(2003) and WEF (2000) For all the modeled
biotower influent wastewaters, the BOD loading is
not more than 0.25kg BOD/m3*day. Thus the
operating dose was given to be 10-30 mm/pass, and
the flushing dose is > or = to 200 mm/pass. Since
the biotower design on the effluents of the RBC
configuration selected, the biotower design based
from the 7-2-2 RBC series is presented below
together with the “biotower” design for other RBC
configurations.
The “biotower” theoretical performance in terms of
BOD removal was derived from the function
provided by Metcalf and Eddy (2003):
n
Se
= e − kD / q
So
Where:
S e = BOD concentration of settled filter effluent (g/
m3 )
S o = influent BOD concentration to the filter (g/
m3 )
k = wastewater treatability and packing coefficient
based on n (L/s)0,5 / m2
D = depth of packing (m)
q = hydraulic application rate of primary effluent, excluding
recirculation (L/m2sec)
Willingness-to-Pay Survey
The survey design using stratified random sampling
(SRS) and the sample size for each barangay (the
single stratum) based on the 2000 Philippine Census.
The sampling design for the WTP survey would have
to be updated if to use the 2007 Philippine Census
results.
Survey questionnaire (see Appendix X) was written in
Filipino language, pre-tested in personal interviews
and was finally administered personally by the author.
Some general comments were solicited as well
through semi structured interviews. The WTP
amount elicited are summarized in Table 29.
The first of two parts of the questionnaire is to
profile respondents and respondents’ current
sanitation and water consumption patterns. Analyses
and correlations of these variables are not part of this
thesis work.
But from tallies, most of the
respondents of spend at least about Php 150
(approximately 22 SEK) for MWSI water bill and
would spend some more to buy bottled drinking
water.
The total monthly household expenditure on water
compared to monthly income can be very high in
some very low income households while higher
income households will only spend a small fraction of
their income for water. Some respondents even
revealed relying on free Barangay Hall water supply
or illegally connected tap for their water.
n = 0.5 is normally assumed
(Metcalf and Eddy 2003, p.917)
Using the designed RBC 7-2-2 series and its design
“biotower” filter area for “dry weather” 2025 to treat
wet weather (with wet weather load) lower TKN
removal can be expected. Since there is significant
difference in the required filter area to remove 90%
TKN in the dry weather and wet weather, it is
possible to adapt the design for dry weather 2025
even with the wet weather loads. Table 27 shows
that 50-85% TKN removal can still be expected in
wet weather operations of the dry weather designed
“biotower”.
Summary of Results
The design most adaptable is the combination of the
7-2-2 Series and its corresponding “biotower” designs
for DRY weather until year 2025. For outfalls 02, 05,
09, 06, 07 and 08, the theoretical BOD effluent
concentrations are given in Table 24. The 2 other
drainage outfalls where several sub catchments
81
Trina Go Listanco
TRITA LWR MASTER
Table 26. Theoretical TKN removal of “biotower” designed for DRY weather 2025 during average WET weather 2025
Lateral #
Filter Area [m2]
WET Weather (for
90% TKNremoval)
Manhole #
Filter Area [m2]
WET Weather
using 2025 DRY
design
% removal with DRY
weather filter area
NL 50
114
363,44
220,00
54
NL 51
205
217,10
138,90
57
NL 49
177
99,38
59,41
54
77
77
52,50
29,56
50
60
60
106,54
113,12
95
34,00
27,70
73
396,67
238,73
54
Outfall02
Outfall02
NL48
8
Outfall05
Outfall05
78,70
75,16
86
Outfall09
Outfall09
340,66
196,98
52
Outfall06
Outfall06
141,20
91,55
58
Outfall07
Outfall07
60,89
50,28
74
Outfall08
Outfall08
76,28
53,69
63
NL 53
251
150,21
117,24
70
NL 54
230
627,96
379,97
54
Table 27. Summary of theoretical load reduction in 2 other outfalls to EDV
DRY weather
designs
BOD prod
(g/day)
BOD after
the RBC
shafts
(g/day)
Flow
rate
m3/day
BOD
concentratio
n after RBC
(g/m3)
BOD
Loading
after
BIOTOWE
R
(g/day)
Outfall: 193
5,936,061
817,201
15,428
53.0
WITHOUT
TREATMENT 193
5,936,061
5,936,061
15,428
384.7
Outfall: 225
3,513,510
635,822
11,618
54.7
WITHOUT
TREATMENT 225
3,513,510
3,513,510
11,618
302.4
Outfall: 193
5,936,061
2,236,979
WITHOUT
TREATMENT 193
5,936,061
Outfall: 225
3,513,510
WITHOUT
TREATMENT 225
3,513,510
BOD
Concentrati
on after
BIOTOWER
(g/m3)
359,559.0
23
173,847
15
1,078,464
.4
27
502,395
22
WET weather designs
39,907
56.1
5,936,061
39,907
148.7
670,422
22,493
29.8
3,513,510
22,493
156.2
82
Table 28. Comparison of different possible RBC
configurations in terms of filter area requirement for
succeeding Biotower treatment
RBC
series
configuration
DRY
weather
filter
area
[m2]
Wet
weather
filter
area
[m2]
Configuration 1)
1895
2772
Configuration
15- 2 stages
2)
1918
2867
Configuration
15-3 stages
2)
1705
2389
Configuration
7-2-2 aerated
2)
1793
2746
wastewater treatment in the catchment gives clues on
environmental values or priorities of the respondents.
The range of answers is wide. (Fig. 54) The mean
WTP amount can be considered as the maximum
expected cash flow for the establishment of the
wastewater treatment system. There are various
opinions on how to collect the hypothetical fees for
the proposed wastewater treatment system. Some
interview respondents feel that MWSI should be in
charge of collecting fees and others feel that
management of a wastewater treatment system
should remain a government task. Some respondents
also wished that a new private organization can lead
the management of a new system. The varying
opinions and ideas of respondents are not analyzed
sociologically in this thesis, but it reflects different
sentiments of the residents on water and wastewater
issues in EDV catchment.
The situation in the catchment can be very disparate
as can be seen in Figure 53 and Figure 55, and would
translate to various applicable and acceptable
wastewater treatment technologies, projects and
financing. General sentiments of poor water supply
service were also shared in interviews which gave an
idea on how water supply can be a more real priority
than wastewater treatment for many EDV residents.
The second part of the questionnaire introduces the
hypothetical wastewater infrastructure and elicits the
maximum amount willing to be paid by the residents
for such a proposed infrastructure. The introduction
describes current conditions and practice in
sanitation, sewerage and wastewater treatment
facilities (or the lack of) in Metro Manila. A
hypothetical compact and combined storm and
wastewater treatment alternative was presented. A
question on perceived need was also asked.
Elicitation method for WTP during the preliminary
survey was in the form of “direct open-ended”
question and “bargaining session”. This allows the
respondents the freedom to honestly weigh and value
the wastewater treatment service based on their
current income; and to give a reasonable amount to
be paid in addition to the existing expenses. The
open ended questions do not provide “cues” but
sometimes would be answered in extremely low
amount.
From the initially surveyed samples, a range of
amount options from were created. In the actual
survey, people are asked an open-ended question and
provided the range of possible amounts. The
analyses of all other components of the questionnaire
are beyond the scope of this thesis.
“Strategic bias” was observed when respondents
understated their WTP for the proposed wastewater
treatment system, or would deliberately choose the
smallest amount in the given price ranges. It can be
ironic to get higher WTP amount from low income
respondents than higher income respondents.
Since wastewater treatment is a responsibility
traditionally delegated to governments, the WTP for a
Results
Almost 90% of respondents answered “urgently
needed” to the question of felt necessity for the
proposed wastewater treatment, which reflects desire
for a improvement in urban environment and
infrastructure and in public spaces. Many however,
tend to believe that these transformations would take
a very long in reality. Many also mention how
corruption and non-cooperation of many people
would further delay infrastructural reforms. About
2% of the respondents answered that the
hypothetical and proposed wastewater treatment
system is not needed at all. The mean WTP amount
for each of the barangay is summarized in Table 29.
The mean WTP amount for the entire EDV
catchment is derived from the resulting monthly
WTP of each barangay. It is estimated to be Php
90.7 or Php 91.00 per month for the whole
catchment. Because of the difference in income and
WTP ranges of the population in EDV, cross-sectoral
subsidies can be introduced. The mode of collection
preferred is apparently through the MWSI monthly
water bill. However, since not all households have
water supply connection with MWSI, an alternative
mode must be created.
Implications on pricing:
Currently, MWSI charges additional 50% of the water
consumption as “sewerage fee” for those connections
tapped into the sewer lines. A sewerage connection
fee of (Php 6000) is also charged initially to a new
client. Although the results of the WTP survey
predict a total about Php 3.8 million of collection per
month, the amount is non binding. Since the amount
willing to be paid differs largely among barangays, the
average amount of about Php 90.00 estimated for the
entire EDV catchment, +/- 10% can be initially
charged. The capitalization for the first stages of
construction and early stages operations of designed
treatment system may have to be financed extermally.
The total amount collectible from the barangays may
be sufficient for monthly operations. It is necessary
to explore other financial arrangement.
83
Trina Go Listanco
TRITA LWR MASTER
Table 29 Amounts willing to be paid by each Barangay, in Philippine Peso, as of Novermber
2007. All amounts are rounded up.
BRG
Y ID
WTP
(PhP
per
mont
h)
BRG
Y
BRG
Y ID
WTP
(PhP
per
mont
h)
BRG
Y ID
WTP
(PhP
per
mont
h)
BRGY
ID
ID
WTP
(PhP
per
mont
h)
WTP
(PhP
per
month)
417
70.5
526
26.5
547
22.6
568
154
627
0.
418
83.6
527
117.6
548
46
569
40.3
628
394.83
419
112
528
76.2
549
63.4
572
34.8
629
24.65
420
325
529
43.3
552
48.3
573
59.2
630
85.47
421
45.8
530
10.9
554
204
574
37.5
631
38.22
422
233
531
27.2
555
54.4
575
9.70
632
40.77
423
495
532
163.2
556
15
576
119.2
633
41.85
424
94.4
533
68.6
557
33
577
34.8
634
443.30
425
157
534
7.3
558
26.2
578
35.6
636
92.66
426
31.5
535
32.6
559
25.7
579
10
636
92.66
427
34.8
536
229
560
34.4
580
102.4
636
92.66
428
34.4
537
54
561
267.3
581
48.5
436
10.5
538
50
562
543
582
0.00
437
15.6
539
213
563
17
583
192
446
12.0
540
111
564
37.5
584
164.
523
16.6
541
65.3
565
59
585
10
524
12.7
545
17.3
566
14.
626
64
525
17.2
546
60
567
56
627
0.00
Fig. 53 Estimated water consumption per capita per day of
each Barangay, values in legend are in liters per day
84
Fig. 55
Surveyed Mean Income of each Barangay Map values in legend
are in Philippine Peso as of November 2007
Fig. 54
Willingness-to-pay Map, values in legend are in Philippine Peso,
as of November 2007
85
Trina Go Listanco
IMPLEMENTATION
M A I N T E NA N C E
TRITA LWR MASTER
and environmental remediation; and should also be
done in a way that appeal to the peoples’
understanding and needs. Ultimately, through the
IEC and the visible onsite installations, peoples’
perspectives and ways can be transformed so they
will be encouraged to participate, take responsibility
for public spaces, and take stock in public
infrastructures and urban ecology.
A decentralized treatment system in 2025 for about
300,000 people in about 260 hectares of catchment
space involves transformation not just of landscapes
but also of peoples’ attitudes and urbanism. It
demands strong involvement, cooperation and
organization, not just of mechanical components, but
of all stakeholders. And since the issue is highly
connected with other major issues e.g. solid wastes,
urban poverty and informality, this proposed
treatment system’s success depends also in the
sincerity of parallel and complimentary efforts to
address these related issues.
Monitoring the effluents and performances of the
treatment units necessitates multiple site facilities.
The organization of wastewater treatment monitoring
is not detailed in this thesis, but emerging
communication technologies (e.g. SMS based
reporting) and remote measuring systems are
potentially applicable in the proposed system.
Monitoring is preferably done daily and at inletoutlet of RBC and the “biotower”.
AND
This
section
summarizes
and
highlights
implementation and maintenance guidelines for all
the designed components proposed in this thesis.
The guidelines are rather obvious, and take much
from basic principles of drainage maintenance. In
general, the whole concept of a combined “inline”
storm and wastewater treatment demands reliable and
flexible treatment units without needing sophisticated
maintenance, monitoring and operation.
The
components that need special attention are the RBC
shafts and aeration systems, including the effluent
pump. The rest, are rather charges that are straight
forward and “not highly technical and delicate”. But
due to the spatial and social factors such as high
population density, poor (if not lack of) solid waste
management, the proposed combined “inline”
treatment system along public infrastructural spaces,
demands active and regular maintenance. “Drainage
maintenance” however, in this thesis means a new
and different level of “de-clogging” drains. It is ideal
to maintain minimal sediments in the drains.
Since the functions of the treatment system depend
on the whole train of units from upstream
installations, negligence and malfunction in the
upstream installations, necessitate preventive
treatment bypass. Otherwise, the downstream units
can accumulate the damages. It is important that
even though the upstream installations e.g. road inlet
screens, tangential filters and VSB’s are generally
designed with safety factors and simple to maintain,
they still must be kept functioning and operating
within safe limits.
With units at various locations, the level of operation
and management will require several distributed units
and levels of organizations as well. Issues on
institutional arrangements are not discussed further in
this thesis, but the roles of local community
government and the coordination of public (City
Government, MMDA, DPWH) and private sectors
(MWSI) are crucial. Since the drainage system and its
components are mandated to different government
and private agencies, this “inline” treatment along the
drainages stimulates discussions and offers an “urban
catchment management” framework for combined
storm and wastewater.
The availability of maintenance personnel in EDV or
neighboring districts is not foreseen to be problem.
Since, the principles and process monitoring of the
treatment system are rather simple, a few specialized
experts are foreseen to be enough for the entire
system operation.
Sustained public information and education campaign
(IEC) must be kept strong and aggressive at all times,
especially in high density and “depressed” areas. The
campaign should be able to effectively explain
principles, goals and significance of such new
approach to wastewater treatment, flood prevention,
Road Inlet Screens
Construction of drilled metal plates is foremost but
can be done in phases. All road inlets must be
replaced to filter out road litter. Resizing and
reconstruction of existing inlets must be done with
massive IEC. It is also important that the strains are
secured.
Regular cleaning of strains can be scheduled twice a
day on dry weather but more frequently in wet
weather. Typically, street sweepers use broom
brushes to collect road litter, but for inlet
maintenance it is recommended that vacuum type
suction cleaner be used, to prevent soft solids to fall
into the drains.
These equipments required
additional capital investment and energy costs, but
the maintenance can be made more effective. At
least weekly, these strainers should be inspected.
Pre-RBC and Post-RBC Filters
Both filters must be constructed prior to the
construction of other components.
With the
designed depth of 3-5 meters from the drainage
invert elevation, the filter walls and chambers must to
be constructed with strong and reinforced concrete.
The cylindrical screens made of metal wires should
have opening size of 6mm as in fine screens. The
designed depth is 1.0 meters to allow space for
influent wastewaters in case of reduced efficiency of
screen. The secondary chamber serves as primary
settling tank, with a retrievable chute to collect settled
86
solids. This chute is made of rigid woven material
with opening size of 1 um, tied up to a bar, and can
be pulled up mechanically with a simple pulley. The
chamber is has an effective volume of 48 m3 and
depending on the influent flow rates, would have
different retention times. At water reach the level (10
cm) less than the influent elevation, it will be turned
over to a horizontal distributing plank, where a level
of 10 cm must be accumulated before the influent
wastewaters are finally let into the RBC shaft tank.
These distribution systems should always be
maintained and rid of sediments. In case of by-pass,
the sluices at the inlet must be shut before the preRBC filter sluice has been closed.
Both filters should be cleaned at least once a day.
The accumulated garbage and solids in cylindrical
screens must be collected everyday, while the micro
screen bucket in the pre-RBC secondary chamber can
be checked and emptied less often. Approximately 23 personnel, including a van driver and the claw
operator should be able to accomplish the task of
cleaning several manholes a day. A day’s tasks
include checking and collecting the screens and
replacing them on empty ones, closing road to traffic.
Ideally, site schedules should have regular times. All
screenings will be stored in a transit compound prior
to landfill disposal or segregations. Inspections and
repairs can be done through the access manholes.
In case of heavy rains, all treatment must be by
passed. The sluices of the filters must be closed
manually. And the diversion weirs along the drains
must be released. In case of earthquakes, reflectors
in manholes must be kept exposed, or other road
signals must be put in place.
Maintenance costs for regular operations include fuel
and labor, losses to traffic. In total the number of
man power per day needed for 27 RBC series
installations in the EDV site is about 81 per shift.
with moderate traffic (near schools). All the rest of
the selected manholes are in relatively minor or
residential streets. During regular maintenance, of at
least 3 times a week, one tank can be closed at a time,
while the rest can continue in operation. It is
important to limit if not close the pre-RBC effluent
during cleaning. Ideally, the pre-RBC chamber must
be cleaned first before the RBC unit. The cleaning
may last 2 hours in dry weather and longer in wet
weather. But in case of treatment “by-pass”, it is
recommended to close the entire RBC series and seal
the gates from the pre-RBC chamber.
Monitoring, on the other hand, should be several
times a day, especially during start up. But in full
operation, monitoring of biofilm and DO can be
often done through provided manholes. It is thus
important to have at least 2 regular personnel at each
of the remote treatment office to oversee functioning
of the unit. This translates to 54 on site (108 total for
night shifts), regular monitoring personnel at bay,
equipped with radio and emergency pumps.
At flow rates above the average wet weather flow rate
for 2025, the treatment system must be by-passed.
The gates and sluices must be manually sealed. This
necessitates a central flood monitoring office and the
remote operators’ posts in the distributed
installations.
“Biotowers”
“Biotower” casings can be built locally, but the plastic
packing may have to be imported from seasoned
manufacturers or contractors abroad. One of the
expected expensive components of the bio trickling
filter is space.
Difficulties arise especially
construction would displace several houses and
relocating people. The pumping and the dosing
operation require most of the attention. The design
presented in this thesis mentions a polishing VSB
after the “biotower” (Variation 4). This VSB
installation may only be applicable for large vacant
land that could be function as a park in the
“biotower” treatment compound. The dosing rates
were provided in the design chapter. The most
significant risk to “biotower” efficiency is the rain
especially in case of heavy down pour. Although a
cover can be installed to conserve the biofilm, times
with prolonged rains e.g. typhoons, “biotower”
treatment will have to be washed and by-passed.
“Biotowers” can also present hazards and risks to
public during operation and earthquakes.
Using
plastic packing instead of rock media alleviates
possible injuries to personnel in case of structural
failure due to earthquakes or wear and tear.
In
events of cracking and collapse, the “biotower” must
stop operation and must be quickly replaced. Further
investigations and risk management are not included
in this thesis, but is recommended to undertake.
Operational nuisance of the “biotower” include
odors and may be avoided with built in aeration
systems.
Rotating Biological Contractors
RBC’s shafts and discs can be made-to-order locally
or can be acquired in packages from several foreign
manufacturers. Sensitive components of the RBC
unit include the aeration system and the shaft discs.
The RBC tank construction requires most of the
capital cost, because of the amount of earthworks
involved. The designed provided in this thesis
requires at least 6.0 meters of road width, such that
drainage line in a selected site built in the midsection
of the road, has to be reconstructed to one side of the
street. Also, since the full length of 30 meters of
RBC installation will block household pipes
connected to the drain sides, a smaller pipe to serve
these disconnected pipes will have to be constructed.
Maintenance of RBC units with 7-2-2 will require a
certain portion of the road to be closed. Alternate
routes for private and public transport must be
prepared. Manhole 8, is the most critical to handle,
because it is on a major thoroughfare, with heavy
traffic. Manholes 251, 230, and 40 are also in roads
87
Trina Go Listanco
COSTS
AND
TRITA LWR MASTER
Typhoons
RISK MANAGEMENT
Typhoons are perennial hazard in the Philippines, but
EDV is most prone to the floods associated with it.
In case of extremely high intensity rainfall and flow
rates, the “inline” treatment system must be
completely by-passed. Inlet strainers must be kept
clear and clean. Regular maintenance of drainage is
preventive measure to avoid clogging of drainage
lines. Pre-RBC filter sluice must be closed first, in
case of heavy rains. The maximum flow rate
designed to be accommodated by the treatment
system is the average flow rate until 2025. Thus, a
central office monitoring the flow rates shall be able
to signal by-pass procedures to the remote
installations and control personnel early on. The
inline treatment system works most effectively with
increased weather forecast accuracy.
The costs mentioned in this text may not be reflective
of current market values and prices.
Values
presented are either quoted from manufacturers’
websites, or solicited figures from key personnel
interviews in 2007. This chapter aims to provide
some idea of how much the proposed system can
cost.
Possible Costs Schedules
The figures and values presented in this section are
rough estimations of prices and costs from average
wages and gasoline values in 2007. Table 30 presents
rough amounts for different items in the proposed
wastewater treatment system.
The amounts
presented are enough to compare to the possible
financial schedules for capitalization and monthly
operations. These amounts shall be subjected to
adjustments in actual implementation. It is assumed
that most of the employees will be local residents of
the site and that part of the capital and maintenance
costs are to be shouldered by Local Government
funds. Cross sectoral subsidies can be introduced. In
general, the WTP amount is possibly enough to fund
the monthly operations expenditures of the proposed
system. A Barangay chairperson even suggested that
part of the sewerage fees being collected by MWSI be
used for fund proposed treatment system.
Table 30 presents possible cost partitioning of the
treatment system to different stake holders, such that
funds can be retrieved from multiple sources. Since
the combined drainage and sewer serves two
functions mandated to 2 agencies: 1 public and 1
private, both organizations can coordinate
management and finance the system. It is also
possible to dissect the treatment system into
components such that, the maintenance of the pre
and post RBC filters will be charged to the MMDA
and the RBC and the biotower units to MWSI. The
local community government or associations can be
active in maintaining the VSB.
Earthquakes
Structural damages to both the underground
installations and the biotower present important risks
to consider. The construction of underground
structures must be reviewed and secured to avoid
possible collapse of roads. RBC manhole covers
must come with markers and reflectors. In case of
overflows, pumps shall also be readily available in
remote or site offices.
Nuisances
Failure to limit the organic loading in RBC shafts and
“biotowers” may result to “increased probability of
developing excessive biofilm thickness, depletion of
oxygen, deterioration of process performance,
appearance of H2S odours and excessive growth of
nuisance organisms such as Beggiatoa (Tchobanoglous
and Burton, 1991; Grady et al 1999 in Cortez et al
2008) Odors, flies and mosquitoes are most
associated with “biotower” and VSB hazards that can
be avoided with proper unit maintenance.
Inordinate failures of RBC’s and “Biotowers”
Ross et al (2008) have assessed the “inordinate”
failures of different RBC installations worldwide.
From experience, shaft overload has been identified
as main draw back for the structural design of the
RBC. Thus, small light weight material and packing
must be closely designed and monitored. Also, down
scaling the installation shafts could alleviate wear and
tear on shaft mechanisms. Similarly, the wear and
tear on “biotower” plastic media may result in
cracking and structural failures. The plastic packing
for both the “biotower” unit and the RBC requires
replacement after sometime and further assessment
e.g. LCA and EIA can provide risk management
plans and evaluations.
Risk Management
The EDV catchment and the proposed system come
inherently with risks associated to geography and
treatment system selection. A few of the major
threats to public and infrastructure safety are
highlighted in this chapter. Until further assessment
can be done, a more reasonable risk management
plan can be idealized.
88
Table 30. Possible responsibility and resources sharing of treatment system among public and private agencies
Installation
operations
and
their
WTP
fees
MWSI
sewerage
+environmental
charges
Local Gov’t funds
e.g. tax
Motorist tax
MMDA
Funds
Inlet screens
YES
YES
YES
VSB
YES
YES
YES
Pre and post RBC filters
YES
YES
RBC installations
YES
YES
Biotower
YES
YES
Table 31. Possible Cost schedules for infrastructure outlay and operation of proposed treatment system
Installation
Construction
Energy
Labor (O&M)
recruitment
Solids
collection
and
transport
3 personnel per 10 -14
chambers; total of 30 for the
entire EDV
Costs
For
local
Number
items
of
Pre and post RBC filters
Cylindrical
screens
Micro
screen
mesh
Chamber
construction
Php 10,000 each * 57
Php 10,000 each *
57
27
cylindrical
screens
+30
replacements
27 micro screen
buckets + 30
replacements
500,000 each * 54
RBC shaft
9
CFM
wastewater
aerators
Diffusers
Shafts and tank
clearing
or
more,
diffuser
Aeration
and
rotation
of discs
US$ 150 * 30 (initially)
Quoted from CLEAN-FLO
brand, Manufacturer: USA.
1
RBC
3,000,000
block * 30
1 special team of 5 persons =
(6 aeration units/ personnel)
for maintenance and checking
296 total RBC
shafts and tanks
2 monitoring personnel with
shifts at remote control
operators (total 54 personnel
day shift + 54 personnel night
shift)
casing
=
Php
each
3 personnel for regular
cleaning operations, for every
5 RBC series installations
(total 180 personnel)
1 RBC disc and shaft =
200,000 Php * 300
(approx + spare)
Biotower
Land
Total 1792 m2
Land
acquisition
at
10,000 Php per m2
Media and casing = 3.5
Million each* 14
Pumping
costs
1 each “biotower”, (total 13
personnel for the entire EDV
for maintenance and checking
13 biotowers
2000 Php each x 100
Transport
of
collected
solids
Street sweepers provided by
local government; volunteers
or residents’ association
At least 150, to
replace all road
inlets,
plus
additional
coverage in low
elevation areas
225 Million Php +
contingency
Approx. = 3.6 Million
Euros + contingency
200,000
Php per
month
1,500,000 Php + taxes per
month
Road inlet strains
Drilled
plates
Metal
Total
rough
estimates
Php 1150 per person
(initially)
89
Trina Go Listanco
TRITA LWR MASTER
Design Features
The designs presented in this thesis includes “inline”
filters or chambers, on-site and alongside VSB
installations, RBC series and distributed “biotowers”,
all of which are existing technologies for physical and
biological treatment. Physical treatment units mainly
use principles of filtration for solids separation while
biological treatments units (2 aerobic steps) mostly
use principles of attach growth, fixed film systems.
But the proposed “inline” system is a continuous
treatment system, retro-fitted specifically to EDV
drainage system and conditions of: 1) high population
density urban area 2) expensive lands 3) expensive
and disruptive construction of sewage pipes and off
site treatment plants and 4) limited skilled labor.
Models used in this thesis show theoretical
functioning of distributed treatment installations in
selected sites along the drainage lines, in effectively
reducing loads not “on site” but “as they flow”, to
achieve standards for effluents by the time the
influent has reached the outfall.
The installations were chosen from a collection of
other treatment techniques and methods, but were
selected because of their affordability, simplicity and
their reliability---or “appropriateness”. The selected
unit process installations are all considered and “low
energy”, “low skill” demanding. Also, they can be
built in phases.
For example, the proposed
“biotowers” can be built after a few years of
analyzing the performance of the RBC series; and the
air diffusers can be initially placed only for the first
stage to test effects on BOD removal. From
evaluations, the design for year 2025, dry weather
conditions, is most effective to build soonest. The
filters, chambers, VSB’s, RBC’s and “biotowers” for
dry weather flow 2025 are designed to handle highest
concentrations of load. Since components are
underground structures, they are difficult and
expensive to upgrade. Thus, design valid for 2025 is
worth the cost in the long run. Also, with the design
RBC and biotower for dry weather, can still meet
effluent standards (90 percent of the time), although
achieving only 50-85% TKN removal on average wet
weather conditions.
Upstream trains of installations for dry weather 2025,
(if to function as designed) are theoretically capable
of reducing BOD influent wastewaters to achieve the
standard effluent concentration of 50 gm3 to EDV
waters. In wet weather, the predicted effluent is close
almost close to the BOD standard, at 56.1g
BOD/m3. Also, 50-90% (wet and dry season
respectively) of NH4-N is expected to be removed,
although no effluent standard exist for nitrogen and
nitrogen compounds in Philippines, at the moment.
The initial assessment of the “inline” treatment
system and installations prove that filter and RBC
chambers contributes to efficacy of the drainage
system, not just by providing small distributed spaces
for temporary retention and re-routing of storm
waters, but for promoting preventive maintenance of
drains. If maintained and managed diligently, this
CONCLUSION AND
RECOMMENDATIONS
This chapter highlights the new approach, with the
combination of process sequence and unit operations
for the proposed treatment system. This thesis has
presented alternative options to an urgent need in
urban development and encourages discussions and
further assessments in the future.
Summary of principles and approach
Calls for remediation of the Pasig River and its
tributaries (and distributaries) have been news for
decades. This thesis initiates a “non conventional”
approach to rehabilitate one estero catchment.
Significantly, this work draws one’s attention to what
is not as obvious as the solid wastes and fouling
waters in the esteros, but to what urbanism hides
beneath the roads, in canals and drains almost
everywhere. The value of this work lies in planning a
different approach to wastewater collection and
treatment involving “watershed” approaches to urban
storm and wastewater management. The approach
focuses on the drains themselves that conveys urban
runoff, households’ wastewater and some solid
wastes. It proposes to address the problem of
wastewater treatment neither “on site” nor “off site,
but inline”.
This thesis has provided concepts and discussions
for the designs of a physical and 2 step aerobic
biological treatment train that is set to maximize the
drainage spaces, minimize above ground installations.
Although, the proposed installations will not capture
and treat all the flows, it is theoretically capable of
reducing constituent loads before they are discharged
into the estero. The design approach has also
preferred multiple sites upstream as an alternative to
traditional and compartmentalized sewage collection
and treatment system.
The decentralized system and process design, staged
at multiple locations will demand reconstruction of
drainages segments; and will require highly
coordinated management. It demands a change in
paradigm in wastewater treatment as it demands
transformation in management of private and public
sectors. It also demands engagement of actors and
organizations down the community level.
The “in line” approach challenges the conventional
paradigm in centralized urban sanitation systems and
water resources planning by preferring to employ
more people than building longer sewer pipes; by
raising public awareness and involvement; and finally,
by engaging community workers and leaders in urban
environmental-systems thinking. The benefits of the
“inline” treatment can be shared among stakeholders
and the transformation of meanings of esteros and
drainages as “public” spaces will begin.
90
system, not only addresses water pollution hazards,
but also alleviates flooding hazards.
The challenges of the proposed treatment system are
in effective and safe management. The “inline”
treatment requires well coordinated operation and
maintenance works. It also requires available and
reliable energy to collect solids, aerate, rotate and
pump components. These challenges, while difficult
can be solved in a number of ways. This thesis has
briefly mentioned principles of self supporting
systems applicable and renewable energy sources, the
details of which are beyond the scope of this thesis
work. Also, participative approaches to include
informal sectors in urban ecological projects e.g.
maintaining VSB’s, or macropyhte based systems
were identified.
It has brought up possible
organizational devolution of tasks to communities
and sharing of responsibilities among public and
private agencies. It highlights IEC for increased
environmental awareness and competence among the
stakeholders. For example, specific management
duties can be charged to MMDA, to DPWH or to a
third party wastewater treatment contractor.
Distributed operation quarters can also be
established.
1) The hydraulic and hydrological estimations
available to the author at the time of writing of this
thesis is that of Balogh (2008), no other scenarios
were considered in the design, further only average
flow rates were used as basis for the proposed
processes and dimensions
2) Theoretical quantifications in this thesis can only
be done with constituents BOD and TKN, other
constituent flows need further analyses
3) Lack of control mechanisms and features for
consistent and low risk operation especially for
proposed supplementary VSB installations
4) Short assessment of indigenous materials for
treatment unit media and construction for the entire
proposed installations
5) Brief presentation and assessment of necessary
biosolids management system
6) Effective management and monitoring for
decentralized treatment units
This thesis has only touched on one of many of other
potential approaches to combined storm and waste
water treatment system in EDV. But importantly, it
has begun what could be fruitful discussions in the
future for EDV and other urban catchments in
developing countries.
The issue of sanitation has other facets, and water
and wastewater management are just two. It is
recommendable that this “inline” treatment approach
be used as an opportunity to introduce other
sanitation projects and stir innovation for other
alternative and appropriate approaches to
“sustainable urban development” e.g. self supporting
systems.
The designs proposed in this study can be made
replicated and re adjusted to other sites if proven in
at least one pilot plant, and can be integrated in
bigger water cycle planning and management for
“water sensitive cities” (Wong, 2008) e.g.
examinations of groundwater and pollutants in
hyporheic zones, impacts of climate changing,
continuous monitoring of water, promotion of
preventive-adaptive management to natural hazard
and continuous capacity building.
The rehabilitation of EDV will also involve further
investigations on pollutant transport in surface and
subsurface inter-phases. Further assessment on
socio-cultural factors in water use and wastewater
disposal can give more insights to possible
organizational approach. Eventually, the proposed
wastewater treatment will be just a transition for
wastewater reuse.
Recommendations
The main designs introduced in this thesis are aerobic
biological treatment and physical separation methods.
Their performances as been written and estimated in
this work, is mostly theoretical. The last of the
proposed process ends in nitrification and NH4
removal. The proposed sequence can be improved
and upgraded to include denitrification. Such can be
achieved by recycling28 biotower effluents or
introducing some anaerobic batch reactions. This
thesis shortly mentions the options for effluent
recycling in the RBC stages and biosolids
management, but at this point, leaves the task of
designing pumping requirements for sludge recycling
to future researchers.
Essentially, the designs, assumptions and models
lifted from other pilot studies should be verified on
site. The pilot study can provide site specific
conditions for improving the theory and practice of
wastewater treatment in tropical low income urban
areas while educating the people on waste water
treatment, waterways protection and environmental
remediation.
With heightened information and
venues for participation, communities will (hopefully)
imbibe the “watershed” perspectives for improved
estero water quality, human health and urban
environment.
Other major technical and implementation weak
points of the proposed design in this thesis are the
enumerated below. Future research and efforts are
call on to address the following limitations:
Reference from Bengt Hultman (discussant)
“Göteborg Upgrading” (Article)
28
91
Trina Go Listanco
TRITA LWR MASTER
R E F E R E NC E S
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Combined Storm and Wastewater Treatment System for Estero de Valencia, Sampaloc, Manila – Appendices
APPENDIX I
Manhole Id
Dry
weather
flow
rateday
Avg
(m3/sec)
Wet
weather
flow rate
Dry +
Avg rain
Avg
(m3/sec)
105
0.0038
0.0092
1333
245
55
0.0096
0.0164
7575
109
Population
Daily cons
(Liters/day)
BOD
conc
DRY+avg
rain
[mg/l]
TKN
Concentration
Dry (mg/L)
164
67.41
12.26483
5.055959
366
213.47
27.48252
16.00995
BOD
conc
DRY
[mg/l]
TKN
Concentration
Wet (mg/L)
0.0108
0.0185
8833
105
380
221.49
28.52052
16.61178
128
0.0269
0.0461
24260
96
417
243.71
31.26622
18.27851
124
0.0330
0.0573
25429
112
356
205.30
26.71921
15.39745
123
0.0343
0.0596
26415
112
357
205.12
26.76312
15.38407
0.0356
0.0621
27499
112
357
204.87
26.79467
15.365
111
0.0372
0.0651
28578
113
355
203.30
26.66178
15.24714
60
0.0401
0.0608
14989
231
173
114.07
12.96928
8.555119
99
0.0786
0.1282
45155
150
266
163.07
19.95369
12.23052
NL051
NL049
DM10
114
QC
101
NL050+QC
NL050
Projected Manhole data for 2016, Dry and Wet Weather, Highlighted manholes are selected treatment sites
94
0.0807
0.1321
47931
145
275
168.02
20.62863
12.60155
81
0.1223
0.1999
73241
144
277
169.62
20.80067
12.72123
74
0.1249
0.2047
77840
139
289
176.01
21.64252
13.20069
68
0.1388
0.2280
92347
130
308
187.47
23.10055
14.06059
63
0.1524
0.2531
99554
132
302
182.11
22.68043
13.65855
56
0.1608
0.2685
110797
125
319
191.05
23.92823
14.32898
51
0.1628
0.2723
113765
124
323
193.45
24.26138
14.50861
44
0.1643
0.2750
115809
123
326
194.99
24.47801
14.62436
193
0.1673
0.2806
120191
120
333
198.32
24.93929
14.87386
200
0.0009
0.0016
1808
41
975
530.96
73.12386
39.82237
197
0.0073
0.0119
9312
67
593
361.97
44.47709
27.14775
177
0.0105
0.0170
11122
81
491
303.76
36.81566
22.78171
77
0.0097
0.0179
3846
219
183
99.52
13.72486
7.464346
161
0.0003
0.0004
151
158
253
190.77
19.00713
14.3076
253
0.0019
0.0024
1079
152
263
205.71
19.72255
15.42858
252
0.0035
0.0045
1947
155
258
198.50
19.36647
14.88727
171
0.0138
0.0176
7944
150
267
209.21
20.04533
15.69063
154
0.0164
0.0224
9552
148
270
197.05
20.24136
14.77906
39
0.0173
0.0242
10387
144
277
198.68
20.80641
14.90089
NL051plus1
0.0260
0.0394
14437
155
257
169.44
19.30854
12.70764
71
0.0368
0.0590
18704
170
236
146.89
17.66263
11.01646
205
0.0378
0.0608
19251
170
236
146.55
17.69604
10.99136
1
A P P E N D I X I C O N T I NU E D
Outfalls
NL053
NL054
NL048
Projected Manhole data for 2016, Dry and Wet Weather, Highlighted manholes are selected treatment sites
Manhole Id
Dry
weather
flow
rateday
Avg
(m3/sec)
Wet
weather
flow rate
Dry +
Avg rain
Avg
(m3/sec)
267
0.0011
134
0.0077
21
19
BOD
conc
DRY+avg
rain
[mg/l]
TKN
Concentration
Dry (mg/L)
TKN
Concentration
Wet (mg/L)
Population
Daily cons
(Liters/day)
BOD
conc
DRY
[mg/l]
0.0015
251
389
103
80.26
7.716638
6.019431
0.0099
2621
253
158
122.47
11.84236
9.184883
0.0122
0.0159
4947
212
188
143.78
14.12117
10.78354
0.0133
0.0174
5606
204
196
149.02
14.67016
11.17681
11
0.0460
0.0581
19231
207
194
153.15
14.52187
11.48648
185
0.0567
0.0729
24467
200
200
155.38
14.97352
11.65364
8
0.0646
0.0829
30804
181
221
172.03
16.56965
12.90202
243
0.0660
0.0850
33284
171
233
181.21
17.49862
13.59078
256
0.0112
0.0122
6753
143
279
255.93
20.9557
19.19479
261
0.0261
0.0299
15752
143
279
244.24
20.92036
18.31828
262
0.0287
0.0333
17273
143
279
239.93
20.93162
17.99502
263
0.0329
0.0393
19866
143
279
234.30
20.94096
17.57278
248
0.0370
0.0449
22317
143
279
230.32
20.94644
17.27395
247
0.0414
0.0509
24968
143
279
226.95
20.93612
17.02102
173
0.0421
0.0520
25435
143
280
226.52
20.96752
16.98888
258
0.0433
0.0539
26219
143
280
225.03
21.02942
16.8772
227
0.0446
0.0562
27160
142
282
223.73
21.14544
16.77966
260
0.0797
0.0995
47014
147
273
218.76
20.47311
16.40709
40
0.0809
0.1014
47471
147
272
216.73
20.38347
16.25486
230
0.0960
0.1266
53487
155
258
195.60
19.34919
14.6698
224
0.1242
0.1740
70905
151
264
188.63
19.81915
14.14693
225
0.1245
0.1745
71140
151
265
188.73
19.839
14.15454
181
0.0120
0.0201
9663
107
374
222.87
28.05522
16.71507
251
0.0200
0.0337
14135
122
327
194.33
24.54581
14.57498
Outfall02
0.0034
0.0063
4050
73
551
299.94
41.30634
22.49541
Outfall03
0.0050
0.0073
2481
176
228
158.09
17.09253
11.85671
Outfall05
0.0140
0.0197
7293
166
241
171.66
18.09236
12.87446
Outfall09
0.0415
0.0638
23199
154
259
168.24
19.42045
12.61772
Outfall06
0.0231
0.0287
13109
152
262
211.14
19.67388
15.83521
Outfall07
0.0124
0.0151
6851
157
255
210.49
19.14392
15.78654
Outfall08
0.0177
0.0248
6011
254
157
112.35
11.81149
8.426436
Outfall EdV
0.4753
0.7070
287604
143
280
188.32
21.00928
14.12419
2
Manhole Id
Dry
weather
flow
rateday
Avg
(m3/sec)
Wet
weather
flow rate
Dry +
Avg rain
Avg
(m3/sec)
105
0.0038
0.0103
Population
Daily cons
(Liters/day)
BOD
conc
DRY
[mg/l]
BOD
conc
DRY+avg
rain
[mg/l]
TKN
Concentration
Dry (mg/L)
TKN
Concentration
Wet (mg/L)
1645
198
202
74.06
15.14
5.55
0.0096
0.0262
9353
88
452
165.36
33.93
12.40
0.0108
0.0294
10906
85
470
171.73
35.21
12.88
128
0.0269
0.0739
29954
78
515
187.62
38.60
14.07
124
0.0335
0.0930
31397
92
433
156.24
32.51
11.72
123
0.0349
0.0969
32614
92
433
155.78
32.49
11.68
0.0363
0.1012
33954
92
433
155.32
32.45
11.65
111
0.0380
0.1064
35285
93
429
153.52
32.21
11.51
60
0.0433
0.0949
18507
202
198
90.33
14.83
6.77
99
0.0827
0.2055
55753
128
312
125.61
23.41
9.42
NL051
NL049
DM10
114
QC
55
101
NL050+QC
NL050
Projected Manhole data for2025, Dry and Wet Weather, Highlighted manholes are selected treatment sites
94
0.0850
0.2122
59182
124
322
129.11
24.18
9.68
81
0.1299
0.3220
90432
124
322
130.00
24.18
9.75
74
0.1327
0.3313
96110
119
335
134.32
25.14
10.07
68
0.1478
0.3693
114023
112
357
142.94
26.80
10.72
63
0.1624
0.4124
122921
114
350
137.99
26.27
10.35
56
0.1715
0.4395
136804
108
369
144.10
27.70
10.81
51
0.1737
0.4465
140466
107
374
145.65
28.08
10.92
44
0.1753
0.4517
142992
106
378
146.57
28.33
10.99
193
0.1786
0.4619
148402
104
385
148.75
28.86
11.16
200
0.0009
0.0026
2231
36
1114
400.90
83.56
30.07
197
0.0079
0.0188
11498
59
678
283.27
50.85
21.25
177
0.0113
0.0267
13733
71
561
238.45
42.09
17.88
77
0.0105
0.0304
4749
191
209
72.25
15.69
5.42
161
0.0003
0.0005
187
138
290
180.20
21.78
13.51
253
0.0021
0.0032
1333
133
301
192.47
22.55
14.44
252
0.0038
0.0061
2403
136
295
182.92
22.14
13.72
171
0.0149
0.0237
9809
131
306
191.90
22.92
14.39
154
0.0177
0.0319
11793
130
309
171.22
23.14
12.84
39
0.0187
0.0350
12825
126
317
169.43
23.79
12.71
NL051plus1
0.0280
0.0606
17825
136
294
136.09
22.07
10.21
71
0.0397
0.0939
23094
149
269
113.86
20.19
8.54
205
0.0408
0.0973
23770
148
270
113.07
20.23
8.48
3
Outfalls
NL053
NL054
NL048
Projected Manhole data for2025, Dry and Wet Weather, Highlighted manholes are selected treatment sites
Manhole Id
Dry
weather
flow
rateday
Avg
(m3/sec)
Wet
weather
flow rate
Dry +
Avg rain
Avg
(m3/sec)
267
0.0012
0.0019
134
0.0083
0.0134
3236
21
0.0131
0.0218
6108
19
0.0143
0.0238
6921
11
0.0497
0.0785
23745
185
0.0613
0.1001
30210
Population
Daily cons
(Liters/day)
BOD
conc
DRY
[mg/l]
BOD
conc
DRY+avg
rain
[mg/l]
TKN
Concentration
Dry (mg/L)
TKN
Concentration
Wet (mg/L)
310
340
118
74.85
8.81
5.61
222
181
112.18
13.54
8.41
186
215
129.84
16.14
9.74
179
224
134.61
16.77
10.10
181
221
140.05
16.60
10.50
175
228
139.78
17.12
10.48
8
0.0697
0.1140
38034
158
253
154.40
18.94
11.58
243
0.0713
0.1174
41096
150
267
162.10
20.01
12.16
256
0.0121
0.0144
8337
125
319
267.13
23.96
20.03
261
0.0282
0.0371
19449
125
319
242.95
23.92
18.22
262
0.0309
0.0420
21328
125
319
234.98
23.93
17.62
263
0.0356
0.0506
24528
125
319
224.60
23.94
16.85
248
0.0400
0.0588
27555
125
319
217.06
23.95
16.28
247
0.0447
0.0676
30828
125
319
211.20
23.94
15.84
173
0.0455
0.0693
31404
125
320
209.65
23.97
15.72
258
0.0468
0.0727
32373
125
321
206.04
24.04
15.45
227
0.0482
0.0770
33535
124
322
201.71
24.17
15.13
260
0.0861
0.1352
58048
128
312
198.80
23.41
14.91
40
0.0873
0.1386
58614
129
311
195.77
23.30
14.68
230
0.1037
0.1800
66042
136
295
169.85
22.12
12.74
224
0.1342
0.2591
87548
132
302
156.45
22.66
11.73
225
0.1345
0.2603
87838
132
302
156.20
22.68
11.72
181
0.0129
0.0330
11931
94
428
167.49
32.07
12.56
251
0.0216
0.0555
17453
107
374
145.61
28.06
10.92
16.60
Outfall02
0.0037
0.0105
5001
64
630
221.37
47.22
Outfall03
0.0054
0.0110
3064
154
261
129.20
19.54
9.69
Outfall05
0.0151
0.0290
9004
145
276
143.59
20.68
10.77
Outfall09
0.0448
0.1010
28643
135
296
131.29
22.20
9.85
Outfall06
0.0250
0.0388
16186
133
300
193.26
22.49
14.49
Outfall07
0.0134
0.0197
8459
137
292
198.33
21.89
14.87
Outfall08
0.0191
0.0366
7422
222
180
93.97
13.50
7.05
Outfall EdV
0.5107
1.0955
355109
124
322
150.07
24.14
11.26
4
A P P E N D I X II
WET
Weather
Flow rate
[m3/s]
Flow rate
[m3/hr]
212.06
0.0103
37
77.80
34
83.60
0.0262
94
30.55
0.0108
39
74.40
0.0294
106
27.21
128
0.0269
97
29.69
0.0739
266
10.82
124
0.0335
121
23.86
0.0930
335
8.60
123
0.0349
125
22.95
0.0969
349
8.25
114
0.0363
131
22.02
0.1012
364
7.90
111
0.0380
137
21.03
0.1064
383
7.52
QC
60
0.0433
156
18.46
0.0949
341
8.43
NL050+
QC
Selected sites for RBC installations and expected retention times on prototype pre-RBC chamber. Designs are valid for
until year 2025. Underlined manholes are selected sites for RBC installation
99
0.0827
298
9.67
0.2055
740
3.89
94
0.0850
306
9.41
0.2122
764
3.77
81
0.1299
468
6.16
0.3220
1159
2.48
74
0.1327
478
6.03
0.3313
1193
2.41
68
0.1478
532
5.41
0.3693
1330
2.17
63
0.1624
585
4.92
0.4124
1485
1.94
56
0.1715
617
4.67
0.4395
1582
1.82
51
0.1737
625
4.61
0.4465
1607
1.79
44
0.1753
631
4.56
0.4517
1626
1.77
193
0.1786
643
4.48
0.4619
1663
1.73
200
0.0009
3
862.81
0.0026
9
310.45
197
0.0079
28
101.89
0.0188
68
42.57
177
0.0113
41
70.62
0.0267
96
30.01
NL051
NL049
DM10
NL050
Loc
Manhole Id
Flow rate
[m3/s]
Flow rate
[m3/day]
105
0.0038
14
55
0.0096
101
Retention time with
fixed chamber
volume of 48m3
[mins]
Retention time
with fixed
volume of
48m3 [mins]
77
0.0105
38
76.13
0.0304
110
161
0.0003
1
2690.93
0.0005
2
1669.46
253
0.0021
7
389.92
0.0032
12
249.57
252
0.0038
14
212.20
0.0061
22
131.51
171
0.0149
54
53.83
0.0237
85
33.81
154
0.0177
64
45.21
0.0319
115
25.09
39
0.0187
67
42.73
0.0350
126
22.83
NL051plus1
0.0280
101
28.53
0.0606
218
13.19
71
0.0397
143
20.15
0.0939
338
8.52
205
0.0408
147
19.61
0.0973
350
8.22
5
26.29
A P P E N D I X II C O N T I N U E D
Outfalls
NL053
NL054
NL048
Loc
Selected sites for RBC installations and expected retention times on prototype pre-RBC chamber. Designs are valid for
until year 2025. Underlined manholes are selected sites for RBC installation
Retention time
with fixed
volume of
48m3 [mins]
WET
Weather
Flow rate
[m3/s]
Flow rate
[m3/hr]
654.66
0.0019
7
416.93
30
96.39
0.0134
48
59.89
0.0131
47
60.90
0.0218
78
36.73
19
0.0143
52
55.83
0.0238
86
33.61
11
0.0497
179
16.11
0.0785
283
10.19
185
0.0613
221
13.06
0.1001
360
8.00
8
0.0697
251
11.48
0.1140
411
7.01
243
0.0713
257
11.22
0.1174
423
6.82
256
0.0121
44
66.20
0.0144
52
55.37
261
0.0282
102
28.33
0.0371
133
21.59
262
0.0309
111
25.85
0.0420
151
19.04
263
0.0356
128
22.49
0.0506
182
15.82
248
0.0400
144
20.02
0.0588
212
13.61
247
0.0447
161
17.89
0.0676
243
11.84
173
0.0455
164
17.59
0.0693
250
11.54
258
0.0468
168
17.11
0.0727
262
11.00
227
0.0482
173
16.61
0.0770
277
10.39
260
0.0861
310
9.29
0.1352
487
5.92
40
0.0873
314
9.16
0.1386
499
5.77
230
0.1037
373
7.72
0.1800
648
4.44
224
0.1342
483
5.96
0.2591
933
3.09
225
0.1345
484
5.95
0.2603
937
3.07
181
0.0129
46
61.94
0.0330
119
24.26
251
0.0216
78
37.04
0.0555
200
14.42
Outfall02
0.0037
13
217.56
0.0105
38
76.49
Outfall03
0.0054
20
146.96
0.0110
40
72.87
Outfall05
0.0151
54
52.93
0.0290
105
27.56
Outfall09
0.0448
161
17.86
0.1010
364
7.92
Outfall06
0.0250
90
32.02
0.0388
140
20.63
Outfall07
0.0134
48
59.62
0.0197
71
40.51
Outfall08
0.0191
69
41.92
0.0366
132
21.88
Outfall EdV
0.5107
1839
1.57
1.0955
3944
0.73
Manhole Id
Flow rate
[m3/s]
Flow rate
[m3/day]
267
0.0012
4
134
0.0083
21
Retention time with
fixed chamber
volume of 48m3
[mins]
6
A P P E N D I X III
Summary of Configuration 1 RBC Performance in DRY Weather (From Table 20a)
Manhole
Id
Surface area per shaft = 1800m2
DRY
Daily
Flow
Weather
BOD
rate
Flow rate
prod
[m3/day]
[m3/s]
[g/day]
Stage 1
BOD
conc.
[mg/L]
In
sBOD
[g/m3]
Out
sBOD
[g/m3]
E-BOD
[g/m3]
Stage 2
Organic
loading [g
BOD/m2*d]
In
sBOD
[g/m3]
Out
sBOD
[g/m3]
E-BOD
[g/m3]
Stage 7
Organic
loading [g
BOD/m2*d
]
In
sBOD
[g/m3]
Out
sBOD
[g/m3]
E-BOD
[g/m3]
Organic loading
[g BOD/m2*d]
101
0.010753
929.1
436236
469.53
281.7
98.5
164.2
84.76
98.5
50.5
84.1
43.4
13.5
11.1
18.5
9.6
114
0.036331
3139.0
1358150
299.19
179.5
110.9
184.8
322.22
110.9
77.4
129.0
225.0
32.4
28.0
46.6
81.3
94
0.084977
7342.1
2367273
158.03
94.8
79.7
132.8
541.58
79.7
68.5
114.1
465.5
43.3
39.5
65.9
268.7
1052.3
44
0.175261
15142.6
5719664
274.25
164.6
141.4
235.7
1982.58
141.4
123.7
206.1
1734.2
81.6
75.1
125.1
200
0.000927
80.1
89257
1114.18
668.5
53.0
88.4
3.93
53.0
13.4
22.4
1.0
1.7
1.3
2.2
0.1
177
0.011329
978.8
549306
470.19
282.1
100.7
167.8
91.22
100.7
52.1
86.8
47.2
14.1
11.6
19.4
10.6
8.1
77
0.010508
907.9
189957
209.23
125.5
58.8
98.0
49.42
58.8
35.1
58.4
29.5
11.5
9.7
16.1
253
0.002052
177.3
53307
300.72
180.4
38.0
63.3
6.23
38.0
15.2
25.3
2.5
3.0
2.4
4.0
0.4
171
0.014862
1284.1
392361
470.19
282.1
111.7
186.2
132.82
111.7
61.0
101.6
72.5
17.7
14.7
24.5
17.5
39
0.018721
1617.5
513007
94.05
56.4
39.5
65.9
59.18
39.5
29.9
49.8
44.7
14.4
12.6
21.1
18.9
71
0.039712
3431.1
923769
129.64
77.8
59.6
99.4
189.42
59.6
47.9
79.8
152.2
26.0
23.3
38.8
73.9
205
0.040796
3524.8
950790
45.40
27.2
24.3
40.5
79.31
24.3
21.9
36.5
71.5
15.6
14.6
24.3
47.6
11
0.04966
4290.6
949785
221.36
132.8
95.5
159.2
379.52
95.5
73.5
122.5
291.9
36.6
32.3
53.8
128.3
183.1
8
0.069715
6023.3
1521357
133.25
79.9
66.9
111.5
373.20
66.9
57.3
95.6
319.8
36.0
32.8
54.7
263
0.035575
3073.6
981135
319.21
191.5
115.5
192.5
328.63
115.5
79.5
132.4
226.1
32.4
28.0
46.6
79.6
227
0.048167
4161.7
1341412
120.99
72.6
58.3
97.1
224.59
58.3
48.4
80.7
186.5
28.3
25.5
42.5
98.3
40
0.087334
7545.7
2344543
156.40
93.8
79.2
132.1
553.67
79.2
68.4
114.0
477.8
43.6
39.9
66.5
278.8
230
0.103662
8956.4
2641694
89.22
53.5
48.9
81.4
405.18
48.9
44.9
74.8
372.4
33.8
31.8
53.1
264.1
181
0.012916
1116.0
477250
427.65
256.6
99.9
166.5
103.20
99.9
54.0
90.0
55.8
15.5
12.9
21.4
13.3
251
0.021596
1865.9
698132
131.21
78.7
52.7
87.8
90.99
52.7
38.6
64.4
66.8
17.6
15.4
25.6
26.6
Outfall02
0.003677
317.7
200046
629.65
377.8
74.2
123.6
21.82
74.2
28.7
47.8
8.4
5.5
4.4
7.4
1.3
Outfall05
0.015116
1306.0
360160
275.78
165.5
79.9
133.1
96.57
79.9
48.4
80.7
58.5
16.2
13.7
22.8
16.6
Outfall09
0.044796
3870.4
1145734
296.02
177.6
116.3
193.9
416.87
116.3
84.2
140.3
301.8
37.5
32.6
54.4
117.0
Outfall06
0.024987
2158.9
647454
299.90
179.9
99.5
165.9
198.93
99.5
65.1
108.5
130.1
24.5
20.9
34.9
41.8
Outfall07
0.013419
1159.4
338358
291.83
175.1
79.5
132.5
85.36
79.5
46.6
77.7
50.1
14.9
12.5
20.9
13.5
Outfall08
0.019085
1648.9
296880
180.05
108.0
64.2
107.0
98.02
64.2
43.8
73.0
66.9
17.6
15.2
25.3
23.2
7
A P P E N D I X IV
Summary of Configuration 1 RBC Performance in WET Weather (From Table 20b)
2
Surface area per shaft = 1800m
Manhole
Id
101
114
60
94
44
200
177
77
253
171
39
71
205
11
8
263
227
40
230
181
251
Outfall02
Outfall05
Outfall09
Outfall06
Outfall07
Outfall08
WET
WeatherFlo
w rate
[m3/s]
0.02940
0.10120
0.09485
0.21222
0.45166
0.00257
0.02666
0.03043
0.00320
0.02366
0.03504
0.09390
0.09732
0.07849
0.11404
0.05055
0.07697
0.13861
0.18001
0.03298
0.05549
0.01045
0.02903
0.10100
0.03877
0.01974
0.03656
Flow
rate
[m3/day]
2540.2
8744.3
8195.2
18335
39023
222.64
2303.6
2629.2
276.95
2044.6
3027.7
8113.2
8408.6
6781.7
9853.4
4368.2
6650.3
11975
15553
2849.4
4794.3
903.66
2508.1
8726.9
3350.1
1706.0
3159.2
Daily
BOD
prod
[g/day]
436236
1358150
740268
2367273
5719664
89257
549306
189957
53307
392361
513007
923769
950790
949785
1521357
981135
1341412
2344543
2641694
477250
698132
200046
360160
1145734
647454
338358
296880
Stage 1
BOD
conc.
[mg/L]
171.73
115.46
90.328
129.10
146.56
400.89
200.20
72.246
192.47
166.60
59.579
60.347
41.619
140.05
99.083
224.60
90.142
109.96
71.034
167.48
68.186
221.37
143.59
131.27
193.26
198.32
93.972
In sBOD
[g/m3]
103.0
69.28
54.20
77.46
87.94
240.5
120.1
43.35
115.4
99.96
35.75
36.21
24.97
84.03
59.45
134.7
54.09
65.98
42.62
100.4
40.91
132.8
86.16
78.77
115.9
119.0
56.38
Out
sBOD
[g/m3]
69.60
61.66
49.05
72.45
84.72
49.28
76.07
35.12
35.54
64.40
30.40
33.75
23.79
71.00
54.22
97.00
48.01
60.60
40.75
70.19
36.14
60.89
60.54
69.16
81.34
69.44
45.10
E-BOD
[g/m3]
116.00
102.76
81.75
120.74
141.19
82.14
126.79
58.54
59.23
107.33
50.66
56.25
39.65
118.33
90.37
161.67
80.02
101.01
67.92
116.98
60.23
101.48
100.90
115.27
135.56
115.74
75.16
Stage 2
Organic
loading [g
BOD/m2*d]
163.71
499.20
372.20
1229.95
3061.08
10.16
162.27
85.51
9.11
121.92
85.22
253.52
185.24
445.83
494.67
392.34
295.63
672.03
586.84
185.17
160.42
50.95
140.59
558.87
252.30
109.70
131.92
8
In
sBOD
[g/m3]
69.60
61.66
49.05
72.45
84.72
49.28
76.07
35.12
35.54
64.40
30.40
33.75
23.79
71.00
54.22
97.00
48.01
60.60
40.75
70.19
36.14
60.89
60.54
69.16
81.34
69.44
45.10
Out
sBOD
[g/m3]
51.38
55.48
44.76
68.02
81.72
19.46
53.94
29.37
17.08
46.14
26.37
31.59
22.72
61.29
49.81
74.64
43.11
56.01
39.03
52.94
32.32
35.89
45.85
61.55
61.53
46.87
37.35
E-BOD
[g/m3]
85.64
92.47
74.61
113.37
136.19
32.43
89.89
48.95
28.46
76.91
43.95
52.65
37.86
102.15
83.01
124.40
71.85
93.35
65.05
88.23
53.86
59.82
76.41
102.59
102.54
78.11
62.26
Stage 7
Organic
loading [g
BOD/m2*
d]
120.85
449.23
339.68
1154.84
2952.68
4.01
115.04
71.50
4.38
87.36
73.93
237.32
176.86
384.85
454.40
301.90
265.46
621.10
562.11
139.68
143.46
30.03
106.47
497.37
190.85
74.04
109.27
In
sBOD
[g/m3]
23.68
39.39
33.03
54.58
71.55
3.81
23.15
17.41
4.20
20.17
17.04
25.12
19.22
39.12
37.45
37.19
30.43
42.86
33.38
25.39
22.57
11.57
22.16
42.43
29.67
18.53
21.67
Out
sBOD
[g/m3]
20.72
36.69
30.98
52.00
69.39
3.07
20.08
15.75
3.45
17.53
15.63
23.88
18.51
35.81
35.24
32.86
28.32
40.47
32.21
22.33
20.96
9.73
19.50
39.32
26.10
15.92
19.55
E-BOD
[g/m3]
34.53
61.16
51.64
86.66
115.65
5.11
33.47
26.25
5.75
29.22
26.04
39.80
30.85
59.68
58.73
54.76
47.19
67.44
53.69
37.21
34.93
16.21
32.50
65.54
43.50
26.54
32.58
Organic
loading
[g
BOD/m
2*d]
48.74
297.09
235.10
882.78
2507.25
0.63
42.83
38.35
0.89
33.19
43.81
179.41
144.10
224.86
321.48
132.89
174.36
448.71
463.90
58.90
93.04
8.14
45.28
317.74
80.97
25.15
57.19
APPENDIX V
Results for RBC Configuration 2, maximum 2 stages, maximum 15 shafts per stage, DRY Weather 2025
Manhole
Original daily
load, mBOD
[g/day]
Shaft's inflow
load [g/day]
DRY
Flow
rate
[m3/d]
sBOD load at
Stage 1
[g/m2*day]
Num of
Shafts
at
Stage 1
sBOD load at
Stage 2
[g/m2*day]
Num of
Shafts at
stage 2
Effluent
BOD
Conc
[g/m3]
NL 50
101
436,236
436,236
929
14.54
10
6.21
3
29.9
114
1,358,150
949,653
3,139
21.10
15
4.76
15
28.2
253
53,307
53,307
177
17.77
1
3.74
1
25.3
171
392,361
343,538
1,284
14.42
14
12.82
2
37.2
39
513,008
168,434
1,618
14.04
4
12.64
2
32.9
NL 51
71
923,770
463,913
3,431
15.46
10
14.89
4
36.1
205
950,790
150,869
3,525
16.76
3
19.41
2
28.3
200
89,257
89,257
80
14.88
2
1.69
1
18.5
177
549,306
461,528
979
15.38
10
10.07
2
35.2
77
189,957
189,957
908
15.83
4
8.66
2
32.6
60
740,268
740,268
3,744
16.45
15
14.39
5
37.7
Outfall02
200,046
200,046
318
13.34
5
6.22
1
29.6
11
949,785
949,785
4,291
21.11
15
15.53
6
40.7
8
1,521,357
746,403
6,023
16.59
15
17.50
6
37.5
Outfall05
360,161
360,161
1,306
15.01
8
12.65
2
36.6
Outfall09
1,145,734
1,145,734
3,870
25.46
15
15.87
6
43.3
Outfall06
647,454
647,454
2,159
15.42
14
14.24
3
38.1
NL 49
NL 48
Outfall07
338,359
338,359
1,159
14.10
8
10.99
2
34.9
Outfall08
296,880
296,880
1,649
14.14
7
14.64
2
36.4
181
477,251
477,251
1,116
15.91
10
11.58
2
36.8
251
698,133
261,918
1,866
14.55
6
15.96
2
36.4
263
981,136
981,136
3,074
21.80
15
14.29
5
41.0
227
1,341,412
486,231
4,162
16.21
10
14.16
5
35.3
40
2,344,543
1,149,987
7,546
25.56
15
27.14
6
46.6
230
2,641,694
648,702
8,956
18.02
12
22.15
6
35.6
94
2,367,273
498,590
7,342
11.08
15
18.39
5
30.8
44
5,719,664
2,324,585
15,143
51.66
15
83.32
5
67.0
NL 53
NL 54
DM10
9
APPENDIX V CONTINUED
Results for RBC Configuration 2, maximum 2 stages, maximum 15 shafts per stage, WET Weather 2025
Manhol
e
Original daily
load, mBOD
[g/day]
Shaft's inflow
load [g/day]
WET
Flow
rate
[m3/d]
sBOD load at
Stage 1
[g/m2*day]
Shafts
at
Stage 1
sBOD load at
Stage 2
[g/m2*day]
Shafts
at
stage 2
Effluen
t BOD
NL 50
101
436,236
436,236
2,540
14.54
10
4.53
3
53.4
114
1,358,150
1,015,158
8,744
22.56
15
11.11
15
57.2
NL 51
253
53,307
53,307
277
17.77
1
5.47
1
59.2
171
392,361
346,937
2,045
8.26
14
2.05
2
42.1
39
513,008
185,521
3,028
15.46
4
9.98
2
39.5
71
205
923,770
950,790
508,547
308,551
8,113
8,409
16.95
34.28
10
3
11.07
30.54
4
2
40.9
32.7
200
89,257
89,257
223
14.88
2
2.23
1
60.1
177
549,306
465,973
2,304
15.53
10
4.34
2
56.5
77
189,957
189,957
2,629
15.83
4
9.39
2
42.9
60
740,268
740,268
3,744
16.45
15
8.61
5
47.3
Outfall02
200,046
200,046
904
13.34
5
3.23
1
53.7
11
949,785
949,785
6,782
21.11
15
8.89
6
59.0
8
NL 49
NL 48
1,521,357
858,680
9,853
19.08
15
10.70
6
48.9
Outfall05
360,161
360,161
2,508
15.01
8
5.45
2
52.2
Outfall09
1,145,734
1,145,734
8,727
25.46
15
12.01
6
61.9
Outfall06
647,454
647,454
3,350
15.42
14
4.46
3
55.9
Outfall07
338,359
338,359
1,706
14.10
8
3.84
2
54.1
Outfall08
296,880
296,880
3,159
14.14
7
6.86
2
45.6
181
477,251
477,251
2,849
15.91
10
5.24
2
55.2
251
698,133
340,800
4,794
18.93
6
11.92
2
44.7
263
981,136
981,136
4,368
21.80
15
6.43
5
66.2
227
1,341,412
550,158
6,650
18.34
10
10.49
5
47.3
40
2,344,543
1,247,042
11,976
27.71
15
15.63
6
58.7
230
2,641,694
860,580
15,553
23.90
12
17.89
6
41.4
94
2,367,273
717,422
18,336
15.94
15
12.59
5
30.9
44
5,719,664
2,735,219
39,024
60.78
15
49.40
5
57.0
NL 53
NL 54
DM 10
10
A P P E N D I X VI
Results for RBC Configuration 2, maximum 3 stages, maximum 15 shafts per stage, DRY Weather 2025
Manhole
NL 50
101
114
NL 51
253
171
39
71
205
NL 49
200
177
77
60
Outfall02
NL 48
11
8
Outfall05
Outfall09
Outfall06
Outfall07
Outfall08
NL 53
181
251
NL 54
263
227
40
230
DM10
94
44
Original
daily load,
mBOD
[g/day]
Shaft's
inflow
load
[g/day]
DRY
Flow
rate
[m3/d]
Inflow conc
to the 1st
shaft [g/m3]
sBOD
load at
Stage 1
[g/m2*day]
sBOD
load at
Stage 2
[g/m2*day]
Shafts at
Stage 1
Shafts at
stage 2
sBOD
load at
Stage 2
[g/m2*day]
Shafts at
stage 3
Effluent
BOD
after final
stage
BOD
after 2nd
Stage
BOD
after 1st
Stage
436,236
1,358,150
436,236
946,263
929
3,139
469.5
301.5
14.54
21.03
10
15
9.31
11.88
2
6
10.52
13.40
1
3
26.2
29.6
34.0
38.4
60.1
68.1
53,307
392,361
513,008
923,770
950,790
53,307
341,514
159,012
454,660
124,315
177
1,284
1,618
3,431
3,525
300.7
266.0
98.3
132.5
35.3
17.77
14.39
13.25
15.16
13.81
1
14
4
10
3
3.74
12.81
12.18
14.70
16.55
1
2
2
4
2
1.49
15.92
17.22
13.63
14.43
1
1
1
3
2
13.9
29.9
27.1
28.4
21.7
25.3
37.2
31.9
35.8
24.6
63.3
59.9
45.2
51.4
28.2
89,257
549,306
189,957
740,268
200,046
89,257
460,741
189,957
740,268
200,046
80
979
908
3,744
318
1114.2
470.7
209.2
197.7
629.7
14.88
15.36
15.83
16.45
13.34
2
10
4
15
5
1.69
10.06
8.66
14.39
6.22
1
2
2
5
1
0.49
11.47
9.87
15.68
3.14
1
1
1
3
1
8.6
27.2
25.2
30.1
18.4
18.5
35.1
32.6
37.7
29.6
63.3
61.7
57.3
57.6
58.7
949,785
1,521,357
360,161
1,145,734
647,454
338,359
296,880
949,785
694,552
360,161
1,145,734
647,454
338,359
296,880
4,291
6,023
1,306
3,870
2,159
1,159
1,649
221.4
115.3
275.8
296.0
299.9
291.8
180.0
21.11
15.43
15.01
25.46
15.42
14.10
14.14
15
15
8
15
14
8
7
15.53
16.71
12.65
15.87
14.24
10.99
14.64
6
6
2
6
3
2
2
9.71
12.12
7.96
9.31
13.72
13.47
10.00
6
6
2
6
2
1
2
28.7
28.0
25.8
29.3
29.6
27.8
27.1
40.7
36.2
36.6
43.3
38.1
34.9
36.4
65.2
50.0
58.1
73.8
59.4
56.9
53.3
477,251
698,133
477,251
253,133
1,116
1,866
427.7
135.7
15.91
14.06
10
6
11.58
15.63
2
2
13.68
11.13
1
2
28.9
27.4
36.8
35.8
62.3
50.3
981,136
1,341,412
2,344,543
2,641,694
981,136
450,209
1,114,431
536,409
3,074
4,162
7,546
8,956
319.2
108.2
147.7
59.9
21.80
15.01
24.77
14.90
15
10
15
12
14.29
13.47
19.95
14.46
5
5
8
8
10.50
11.78
13.49
15.02
4
4
8
6
29.3
26.7
31.7
25.6
41.0
34.0
42.9
30.2
69.7
48.6
63.5
38.7
2,367,273
5,719,664
474,416
2,262,923
7,342
15,143
64.6
149.4
10.54
50.29
15
15
17.77
81.80
5
5
14.63
66.56
5
5
25.3
55.3
29.9
65.9
36.3
81.0
11
A P P E N D I X VI C O N T I N U E D
Results for RBC Configuration 2, maximum 3 stages, maximum 15 shafts per stage, WET Weather 2025
Manhole
NL 50
101
114
NL 51
253
171
39
71
205
NL 49
200
177
77
Original
daily load,
mBOD
[g/day]
Shaft's
inflow
load
[g/day]
WET
Flow
rate
[m3/d]
Inflow conc
to shaft
[g/m3]
sBOD load
at Stage 1
[g/m2*day]
sBOD load
at Stage 2
[g/m2*day]
Shafts at
Stage 1
sBOD load
at Stage 2
[g/m2*day]
Shafts at
stage 2
Shafts at
stage 2
Effluent
BOD
BOD
after 2nd
Stage
BOD
after 1st
Stage
436,236
1,358,150
436,236
1,010,909
2,540
8,744
171.7
115.6
14.54
22.46
10
15
4.53
11.07
2
6
3.40
8.43
1
3
35.0
38.1
40.1
43.4
53.4
57.0
53,307
392,361
513,008
923,770
950,790
53,307
343,821
177,204
497,202
274,999
277
2,045
3,028
8,113
8,409
192.5
168.2
58.5
61.3
32.7
17.77
8.19
14.77
16.57
30.56
1
14
4
10
3
5.47
2.04
9.64
10.89
27.51
1
2
2
4
2
2.63
1.54
7.92
9.25
25.74
1
1
1
3
2
17.2
27.7
28.5
30.6
25.9
28.5
31.6
31.4
34.2
27.6
59.2
41.9
38.2
40.3
29.4
89,257
549,306
189,957
89,257
463,478
189,957
223
2,304
2,629
400.9
201.2
72.2
14.88
15.45
15.83
2
10
4
2.23
4.33
9.39
1
2
2
0.99
3.15
7.39
1
1
1
15.4
35.3
30.1
26.6
41.0
33.7
60.1
56.3
42.9
60
740,268
740,268
8,195
90.3
16.45
15
8.61
5
6.92
3
33.7
38.0
47.3
Outfall02
NL 48
11
8
Outfall05
Outfall09
Outfall06
Outfall07
Outfall08
NL 53
181
251
NL 54
263
227
40
200,046
200,046
904
221.4
13.34
5
3.23
1
2.25
1
28.2
37.4
53.7
949,785
1,521,357
360,161
1,145,734
647,454
338,359
296,880
949,785
792,001
360,161
1,145,734
647,454
338,359
296,880
6,782
9,853
2,508
8,727
3,350
1,706
3,159
140.1
80.4
143.6
131.3
193.3
198.3
94.0
21.11
17.60
15.01
25.46
15.42
14.10
14.14
15
15
8
15
14
8
7
8.89
10.12
5.45
12.01
4.46
3.84
6.86
6
6
2
6
3
2
2
6.38
8.17
4.10
8.99
3.23
2.64
5.51
6
6
2
6
2
1
2
32.5
31.1
31.1
36.7
33.4
31.1
30.5
42.3
37.3
39.3
46.4
40.5
37.1
36.6
59.0
46.2
52.2
61.9
55.9
54.1
45.6
477,251
698,133
477,251
326,380
2,849
4,794
167.5
68.1
15.91
18.13
10
6
5.24
11.54
2
2
4.00
9.92
1
2
37.0
32.6
42.1
37.3
55.2
43.3
981,136
1,341,412
2,344,543
981,136
504,373
1,198,723
4,368
6,650
11,976
224.6
75.8
100.1
21.80
16.81
26.64
15
10
15
6.43
9.87
15.20
5
5
8
4.22
7.73
11.63
4
4
8
33.0
29.4
35.1
43.5
34.9
43.7
66.2
44.5
57.1
2,641,694
717,023
15,553
46.1
19.92
12
15.44
8
13.24
6
27.6
30.7
35.7
2,367,273
5,719,664
878,203
2,832,778
18,336
39,024
47.9
72.6
19.52
62.95
15
15
14.86
50.88
5
5
13.56
47.39
5
5
30.6
51.1
33.3
54.6
36.5
58.7
230
DM 10
94
44
12
A P P E N D I X VII
Theoretical results RBC configuration with 7-2-2 stage series Note: Underlined figures denote overloaded shafts, and highlighted manholes are installations followed by “biotower”
unit.. BOD conc = concentration in g/m3 (From Table 24)
Manhole
Original
daily
load,
mBOD
[g/day]
Shaft's
inflow
load
[g/day]
DRY
Flow
rate
[m3/d]
Inflow
conc
to the
1st
shaft
[g/m3]
BOD
conc
after
stages
[g/m3]
Remaining
mBOD
[g/day]
Removed
BOD
[g/day]
sBOD load
at Stage 1
[g/m2*day]
Shafts
at
Stage
1
sBOD load
at Stage 2
[g/m2*day]
Shafts
at
stage
2
sBOD load
at Stage 2
[g/m2*day]
Shafts
at
stage
3
Final
Effluent
BOD
Conc
BOD
Conc
after
2nd
BOD Conc
after 1st
NL 50
101
436,236
436,236
929
469.5
24.5
22758
413,478
20.77
7
10.98
2
5.90
2
24.5
38.1
70.9
114
1,358,150
944,672
3,139
301.0
49.1
154263
790,409
44.98
7
49.15
2
34.18
2
49.1
65.3
93.9
NL 51
253
53,307
53,307
177
300.7
10.5
1853
51,454
2.54
7
0.76
2
6.56
0
10.5
11.1
25.7
171
392,361
340,907
1,284
265.5
30.9
39738
301,169
28.77
7
17.61
2
9.98
2
30.9
46.6
82.3
39
513,008
160,385
1,618
99.2
24.4
39392
120,993
13.37
4
12.25
2
8.64
2
24.4
32.1
45.4
71
923,770
450,153
3,431
131.2
37.1
127341
322,812
21.44
7
33.33
2
26.05
2
37.1
45.6
58.3
205
950,790
154,362
3,525
43.8
24.1
84785
69,578
7.35
7
16.29
2
284.64
0
24.1
24.2
27.7
200
89,257
89,257
80
1114.2
5.6
447
88,811
14.88
2
0.84
2
0.18
2
5.6
13.7
63.3
177
549,306
460,495
979
470.5
25.5
24915
435,580
21.93
7
11.86
2
6.42
2
25.5
39.4
72.7
77
189,957
189,957
908
209.2
21.7
19703
170,255
15.83
4
8.66
2
4.94
2
21.7
32.6
57.3
60
740,268
740,268
3,744
197.7
46.5
174176
566,092
35.25
7
48.69
2
36.62
2
46.5
58.7
78.0
Outfall02
200,046
200,046
318
629.7
19.7
6249
193,798
9.53
7
2.65
2
22.19
0
19.7
20.9
50.0
11
949,785
949,785
4,291
221.4
52.8
226513
723,273
45.23
7
63.01
2
47.52
2
52.8
66.5
88.1
8
1,521,357
798,085
6,023
132.5
50.1
301715
496,370
38.00
7
71.23
2
59.08
2
50.1
58.9
71.0
NL 49
NL 48
Outfall05
360,161
360,161
1,306
275.8
26.7
34856
325,305
17.15
7
13.41
2
8.31
2
26.7
38.2
61.6
Outfall09
1,145,734
1,145,734
3,870
296.0
55.7
215594
930,140
54.56
7
65.28
2
46.81
2
55.7
72.6
101.2
Outfall06
647,454
647,454
2,159
299.9
38.5
83110
564,344
30.83
7
28.87
2
19.05
2
38.5
52.9
80.2
Outfall07
338,359
338,359
1,159
291.8
25.0
29003
309,356
16.11
7
11.67
2
7.03
2
25.0
36.4
60.4
Outfall08
296,880
296,880
1,649
180.0
27.1
44604
252,276
14.14
7
14.64
2
10.00
2
27.1
36.4
53.3
13
A P P E N D I X VII C O N T I N U E D
Theoretical results RBC configuration with 7-2-2 stage series Note: Underlined figures denote overloaded shafts, and highlighted manholes are installations followed by “biotower”
unit.. BOD conc = concentration in g/m3 (From Table 24)
Manhole
Original
daily
load,
mBOD
[g/day]
Shaft's
inflow
load
[g/day]
DRY
Flow
rate
[m3/d]
Inflow
conc
to the
1st
shaft
[g/m3]
BOD
conc
after
stages
[g/m3]
Remaining
mBOD
[g/day]
Removed
BOD
[g/day]
sBOD load
at Stage 1
[g/m2*day]
Shafts
at
Stage
1
sBOD load
at Stage 2
[g/m2*day]
Shafts
at
stage
2
sBOD load
at Stage 2
[g/m2*day]
Shafts
at
stage
3
Final
Effluent
BOD
Conc
BOD
Conc
after
2nd
BOD Conc
after 1st
181
477,251
477,251
1,116
427.7
27.2
30402
446,849
22.73
7
13.63
2
7.67
2
27.2
41.2
73.3
251
698,133
251,284
1,866
134.7
26.3
49003
202,281
11.97
7
14.65
2
10.59
2
26.3
34.0
47.1
263
981,136
981,136
3,074
319.2
49.5
152240
828,895
46.72
7
49.40
2
33.98
2
49.5
66.3
96.4
227
1,341,412
512,517
4,162
123.2
40.0
166559
345,958
24.41
7
41.50
2
33.38
2
40.0
48.1
59.8
40
2,344,543
1,169,690
7,546
155.0
60.6
457209
712,481
55.70
7
106.67
2
89.07
2
60.6
70.8
84.8
230
2,641,694
754,360
8,956
84.2
46.1
413136
341,224
35.92
7
85.48
2
76.32
2
46.1
51.1
57.3
94
2,367,273
597,294
7,342
81.4
31.9
233876
363,418
24.89
8
15.68
8
29.54
3
31.9
36.2
51.2
44
5,719,664
2,389,033
15,143
157.8
63.7
964221
1,424,812
99.54
8
63.75
8
121.35
3
63.7
72.1
101.0
NL 54
DM10
14
A P P E N D I X VIII
Biotower design for RBC configuration 2) with maximum 15 shafts at first stage and maximum 2 stages; DRY and WET weather 2025
Manhole ID
114
205
177
77
60
Outfall02
8
Outfall05
Outfall09
Outfall06
Outfall07
Outfall08
251
230
Wet weather
114
205
177
77
60
Outfall02
8
Outfall05
Outfall09
Outfall06
Outfall07
Outfall08
251
230
3,139
3525
979
908
3744
318
6023
1306
3870
2159
1159
1649
1,866
8956
28.22
28.26
35.17
32.61
37.69
29.64
37.53
36.57
43.28
38.13
34.85
36.39
36.38
35.59
32.45
20.23
42.09
15.69
14.83
47.22
18.94
20.68
22.20
22.49
21.89
13.50
28.06
22.12
172.36
148.64
68.49
35.37
150.60
21.99
277.36
62.46
207.40
110.21
56.03
61.97
105.62
439.42
Eff. BOD
conc
[g/m3]
0.01
0.02
0.01
0.04
0.07
0.00
0.04
0.04
0.05
0.03
0.03
0.08
0.02
0.03
8744
8409
2304
2629
3744
904
9853
2508
8727
3350
1706
3159
4794
15553
57.15
32.69
56.50
30.12
47.28
53.68
48.88
52.19
61.93
55.90
54.08
45.57
44.74
41.41
11.65
8.48
17.88
5.42
6.77
16.60
11.58
10.77
9.85
14.49
14.87
7.05
10.92
12.74
369.01
232.31
122.97
54.52
107.31
45.24
386.89
97.33
347.25
158.23
80.57
91.08
175.21
598.86
0.31
0.12
0.15
0.20
0.42
0.15
0.21
0.28
0.48
0.21
0.19
0.36
0.18
0.12
Q Dry Weather
(m^3/day)
BOD
(g/m^3)
TKN DRY(g/m^3)
Filter Area
[m2]
15
TowerDiam
[m]
AirFlow
[m3/s]
86.18
74.32
34.25
17.68
75.30
11.00
138.68
31.23
103.70
55.11
28.02
30.98
52.81
219.71
9
7.8
3.6
1.8
7.9
1.1
14.5
3.3
10.8
5.8
2.9
3.2
5.5
22.9
0.25
0.27
0.10
0.08
0.35
0.03
0.58
0.13
0.43
0.22
0.11
0.15
0.18
0.84
BOD
loading A
[g/m2*day]
0.84
1.10
0.82
1.37
1.54
0.70
1.34
1.25
1.32
1.22
1.18
1.59
1.05
1.19
184.51
116.16
61.48
27.26
53.66
22.62
193.44
48.66
173.63
79.12
40.29
45.54
87.60
299.43
19.3
12.1
6.4
2.8
5.6
2.4
20.2
5.1
18.1
8.3
4.2
4.8
9.1
31.2
1.15
0.65
0.32
0.18
0.39
0.12
1.13
0.30
1.21
0.44
0.22
0.32
0.51
1.56
2.22
1.94
1.74
2.38
2.70
1.76
2.04
2.20
2.55
1.94
1.88
2.59
2.01
1.76
Pumping rate
[L/s]
BOD loading V
[kg/m3*day]
0.08
0.11
0.08
0.14
0.15
0.07
0.13
0.13
0.13
0.12
0.12
0.16
0.11
0.12
0.22
0.19
0.17
0.24
0.27
0.18
0.20
0.22
0.26
0.19
0.19
0.26
0.20
0.18
A P P E N D I X VIII C O NT I N U E D
“Biotower” design for RBC configuration 2), maximum 15 shafts in first stage, maximum 3 stages in DRY Weather, 2025
Manhole #
Q Dry
Weather
(m^3/day
BOD
(g/m^3)
29.61
Filter Area
[m2]
Effluent
BOD
conc
[g/m3]
Pumping
rate [L/s]
32.45
176.05
0.01
88.02
TKN
DRY(g/m^3)
TowerDiam
[m]
9.2
AirFlow
[m3/s]
0.26
BOD
loading A
[g/m2*day]
0.87
BOD loading V
[kg/m3*day]
114
3,139
0.09
205
3525
21.74
20.23
132.44
0.01
66.22
6.9
0.21
0.95
0.09
177
979
27.20
42.09
61.17
0.00
30.58
3.2
0.08
0.71
0.07
77
908
25.24
15.69
31.59
0.02
15.80
1.6
0.06
1.19
0.12
60
3744
30.07
14.83
136.36
0.04
68.18
7.1
0.29
1.35
0.14
Outfall02
318
18.41
47.22
17.84
0.00
8.92
0.9
0.02
0.54
0.05
8
6023
28.00
18.94
243.80
0.02
121.90
12.7
0.45
1.13
0.11
Outfall05
1306
25.83
20.68
53.59
0.01
26.80
2.8
0.09
1.03
0.10
Outfall09
3870
29.29
22.20
174.66
0.02
87.33
9.1
0.31
1.06
0.11
Outfall06
2159
29.59
22.49
98.58
0.02
49.29
5.1
0.17
1.06
0.11
Outfall07
1159
27.83
21.89
50.75
0.01
25.37
2.6
0.09
1.04
0.10
Outfall08
1649
27.05
13.50
54.39
0.03
27.19
2.8
0.12
1.34
0.13
251
1,866
27.36
28.06
93.16
0.01
46.58
4.9
0.14
0.90
0.09
230
8956
25.57
22.12
379.97
0.01
189.98
19.8
0.63
0.99
0.10
16
A P P E N D I X IX
“Biotower” design for RBC configuration 7-2-2 in DRY Weather, 2025
Manhole #
Q (m^3/day
BOD (g/m^3)
TKN DRY(g/m^3)
Filter
Area
[m2]
Effluent
BOD conc
[g/m3]
Pumping
rate [L/s]
TowerDiam
[m]
AirFlow
[m3/s]
BOD
BOD loading V
loading A
[kg/m3*day]
[g/m2*day]
114
3,139
49.14
32.45
220.00
0.035
110.0
11.5
0.41
1.15
0.11
205
3525
24.23
20.23
138.90
0.010
69.4
7.2
0.23
1.01
0.10
177
979
25.45
42.09
59.41
0.002
29.7
3.1
0.07
0.69
0.07
77
908
21.70
15.69
29.56
0.013
14.8
1.5
0.05
1.09
0.11
60
3744
19.67
14.83
113.12
0.011
56.6
5.9
0.20
1.07
0.11
Outfall02
318
50.09
47.22
27.70
0.017
13.9
1.4
0.04
0.94
0.09
8
6023
26.69
18.94
238.73
0.016
119.4
12.5
0.43
1.10
0.11
Outfall05
1306
55.70
20.68
75.16
0.116
37.6
3.9
0.18
1.59
0.16
Outfall09
3870
38.50
22.20
196.98
0.036
98.5
10.3
0.39
1.24
0.12
Outfall06
2159
25.01
22.49
91.55
0.009
45.8
4.8
0.15
0.97
0.10
Outfall07
1159
27.24
21.89
50.28
0.013
25.1
2.6
0.09
1.03
0.10
Outfall08
1649
26.26
13.50
53.69
0.030
26.8
2.8
0.11
1.32
0.13
251
1,866
46.13
28.06
117.24
0.039
58.6
6.1
0.23
1.20
0.12
230
8956
25.57
22.12
379.97
0.010
190.0
19.8
0.63
0.99
0.10
17
A P P E N D I X IX C O NT I N U E D
“Biotower” design for RBC configuration 7-2-2 in DRY Weather, 2025 with TKN production per capita per day of 7.5 g
Manhole #
Q
(m^3/day
BOD
(g/m^3)
TKN
DRY(g/m^3)
81.13
Filter Area
[m2]
Effluent
BOD conc
[g/m3]
515.9819
0.020018
257.991
Pumping
rate [L/s]
AirFlow
[m3/s]
BOD loading
A [g/m2*day]
BOD loading
V
[kg/m3*day]
26.9
0.906010068
1.059807257
0.105980726
TowerDiam
[m]
114
3,139
29.61
205
3525
21.74
50.57732
350.1662
0.011674
175.0831
18.3
0.595928156
1.018649726
0.101864973
177
979
27.20
105.2247
167.0068
0.005861
83.50342
8.7
0.233776655
0.798121971
0.079812197
77
908
25.24
39.22997
91.0804
0.044699
45.5402
4.8
0.201516796
1.425206681
0.142520668
60
3744
30.07
37.06796
154.3506
0.040557
77.17529
8.1
0.325225895
1.338268926
0.133826893
318
18.41
118.0601
56.90088
0.003208
28.45044
3
0.074326404
0.733241868
0.073324187
6023
28.00
47.35824
529.6701
0.0106
264.835
27.6
0.851699019
0.948363307
0.094836331
Outfall05
1306
25.83
51.70834
129.5245
0.012491
64.76223
6.8
0.215216093
0.988317144
0.098831714
Outfall09
3870
29.29
55.50467
460.5577
0.02511
230.2788
24
0.855647207
1.138743713
0.113874371
Outfall06
2159
29.59
56.2315
210.8605
0.008063
105.4302
11
0.316783649
0.87112552
0.087112552
Outfall07
1159
27.83
54.71888
105.559
0.005956
52.77952
5.5
0.151743387
0.824748698
0.08247487
Outfall08
1649
27.05
33.75875
127.4264
0.028098
63.71319
6.6
0.252689712
1.237856498
0.12378565
251
1,866
27.36
70.15549
254.612
0.014017
127.306
13.3
0.429080538
1.006100434
0.100610043
230
8956
25.57
55.30318
836.4069
0.005715
418.2035
43.6
1.220756832
0.840404897
0.08404049
Outfall02
8
18
APPENDIX X
Willingness to Pay Survey Questionnaire
Good Day. I am a student of Environmental Engineering and Sustainable Infrastructure in the Royal Institute of
Technology, Stockholm. This survey is needed for my Master´s Thesis about the establishment of a “wastewater
treatment system” for the Rehabilitation of Estero de Valencia and Flood control. This system is for the
remediation of our esteros and wastewaters in the canal to also alleviate flooding and pollution. I ask that you
answer the questions as accurate and as honest as possible.
Please encircle your answer:
1)
Ownership of house and land:
a) Legitimate Owner of house and land
b) Tenant / renter
c) Owner of the house but not the land
2) How much is your total household income per month?
Please specify the amount in Pesos____________
3) Does your household have a private metered connection to Maynilad Water Service Inc (MWSI) ?
a) Yes, we have 2) None
3.a) If yes you have a metered private water supply connection, is it
a) residential b) semi-business c) high rise d) commercial water connection type?
How much is your usual monthly bill for this water connection/ supply?
Please specify amount in Pesos ___________.
3. b) If your household has no connection to the MWSI, where do you get your water for washing?
a) deep well b) buy from neighbours who has MWSI connection c) others, specify__________
Where do you get your water for drinking?
a) Drinking (bottled) water vendors b) boil water bought from neighbors c) others, specify__________
How much do you spend for buying and getting water in a month?
Please specify in Pesos _______________
4) Does your household have a septic tank or is connected to one?
a) yes b) no
If no, how much are you willing to pay for you to have one?
Please specify amount__________
Currently, many of the houses are not connected to the Sewer lines of MWSI / MWSS, and so most of the
wastewater from the houses e.g. grey water, sewage etc, go directly into the drains instead of going to the sewers.
These wastewaters thus are discharged without any treatment into the estero (Estero de Valencia). One of the main
aims of my thesis is to design a combined storm and wastewater treatment system where the wastewaters in the
drains will have to be “cleaned” before it gets discharged in the EDV.
5) In your opinion, do you think that for those who are not connected to the sewer line, this combined storm and
wastewater treatment system is needed for the cleanliness of waters in drains and for the rehabilitation of the estero?
a) Yes, urgently needed b) needed but in the next 5 years c) needed but in the next 10 years d) not needed at all
Currently, MWSI charges 50% of your water consumption in addition to your total water bill if you are connected to
their sewer lines. However, there are alternatives to putting new sewer lines in your area to minimize the costs and
disruptions of ground works for the laying of pipes. One such treatment alternative can make use of the drainage
19
line to be the site of the treatment where wastewater can be mechanically, physically filtered or cleaned as it passes
through the drainages. Such a treatment alternative can be called an “interceptor system” in the drains.
6) If there will be a possibility of installing such drain interceptors system for wastewater treatment system, how is
the maximum amount you are willing to pay for such a service?
a) 50% of monthly bill
b) fixed user fee, 20-50 pesos monthly
c) fixed user fee, 50-100 pesos monthly
d) fixed user fee, 100 – 200 pesos monthly
e) fixed user fee, 200 – 300 pesos monthly
f) fixed user fee, mahigit sa 300 pesos monthly
g) other amount please specify______________pesos
7) Which agency would you rather or prefer to handle such wastewater treatment management?
a) MWSI
b) DPWH
c) MMDA
d) DENR
e) new private company
specializing in wastewater treatment system
Thank you for your participation in this survey.
Questionnaire in Filipino Language
Magandang Araw Po. Ako po ay isang estudyante ng Environmental Engineering and Sustainable Infrastructure sa
Royal Institute of Technology, Stockholm. Ang survey na ito ay kailangan ko para sa aking Master’s Thesis tungkol
sa pag–tatayo ng isang: “wastewater treatment system” (Establishment of Wastewater Treatment System for Estero
Rehabilitation and Flood Control) Ito po ay para sa ikalilininis ng mga estero at ng mga tubig sa ating mga kanal para
makaiwas sa pagbaha at polusyon. Kung maaari ay paki sagot po nang matapat at tama ang mga katanungan.
Paki-bilugan ang letra ng inyong sagot:
1) Pag mamay ari ng tinitirahan at lupa, Kayo po ba ay:
a) may-ari ng lupa at bahay (owner)
b) nangungupahan (renter/ tenant)
c) hindi may ari ng lupa pero may ari ng bahay
2) Magkano po ang kabuuang kita (total monthly income of household) ng inyong “household” o kabahayan sa isang
buwan? Kung renter, magkano po ang inyong kita o ang kita ng ningyong mag-anak na nangungupahan buwan
buwan?
Pakisulat po ang sagot: ( _________________ )Pesos sa isang buwan (kahit hindi eksaktong halaga)
3) Kayo po ba o ang inyong tinitirahan ay may linya (may metro) o kaya ay naka kunekta sa linya ng tubig ng
Maynilad?
a) Meron
b) Wala
3.a) Kung meron: (Pakibilugan ang letra ng inyong sagot)
Ang linya po ba na iyon ay: a) residential line
b) semi-business line
c) high rise line
d) commercial line
Magkano po ang karaniwang konsumo o bayarin ninyo ng tubig sa isang buwan? (Karaniwang Maynilad Billing o
kaya’y kontribusyon sa bayarin ng tubig sa isang buwan)
Pakisulat ang sagot: _______________pesos sa isang buwan
3.b) Kung walang linya sa Maynilad: (Pakibilugan po ang letra ng inyong sagot)
Saan po kayo kumukuha ng tubig pang hugas?
a) deep well
b) bumibili sa kapit bahay na may linya o metro sa Maynilad
c) kung sa iba pakisulat po kung saan __________.
Saan po kayo kumukuha ng tubig na maiinom (drinking water)?
a) bumibili
b) pinakukuluuan ang tubig sa deep well or binili sa kapit bahay
c) kung sa iba pa, pakisulat po kung saan __________
20
Magkano po ang karaniwang nagagastos ninyo para sa pag bili at pag kuha ng tubig at pag bili ng tubig sa isang
buwan? (Kahit sa inyong tansya o estima)
Pakisulat po ang halaga: _________________ pesos kada buwan.
4) Kayo po ba ay may septic tank o “poso negro” o hukay para sa dumi mula sa kubeta?
a) oo, meron
b) wala,
Kung wala, magkano po ang kaya ninyong bayaran para magkaroon ng “septic tank”/ “poso negro” Pakisulat ang
sagot: _____________ (Pesos)
Sa ngayon, hindi po lahat ng kabahayan at negosyo ay nakakabit sa “sewer lines” ng Maynilad. Ibig sabihin po nito,
ang tubig na ginamit sa kubeta (kung walang septic tank), kusina, labada o mga “waste water” ay pumupunta diretso
sa ating mga “drainage canals” (sa halip na sa “sewer lines”) at tutuloy sa ating mga estero nang hindi man lamang
nalilinis (walang treatment). Isa po ito sa mga dahilan ng polusyon at pag dumi ng ating mga kanal at mga estero. Isa
po sa layunin ng aking pag aaral ay ang pag-disenyo ng isang “wastewater treatment system” kung saan ang tubig na
dumadaloy sa mga kanal na galing sa kalsada, ulan at kabahayan, ay lilinisin bago dumating sa estero.
5) Sa inyong palagay, kinakailangan po ba ang isang ”waste water treatment” para sa mga walang ”sewer lines” upang
malinis ang tubig at mabuhay ang mga estero?
Paki bilugan ang inyong sagot.
a) kailangang kailangan sa ngayon
c) kailangan sa loob ng 10 taon
b) kailangan sa loob ng 5 taon
d) hindi kailangan
Sa kasalukuyan, kapag nakakunekta ang bahay sa ”sewer lines” o tubo ng Maynilad na papuntang Tondo waste water
treatment plant, sinisingil po sila ng karagdagang 50% ng konsumo sa tubig bilang ”sewerage fee”. Isang mas
matipid at alternatibong paraan ang pag kolekta ng waste water ay ang pag linis nito sa mismong ”drainage canals”
upang hindi na po mag huhukay ng mga kalsada para sa maglagay pa ng bagong mga tubo para sa ”sewer lines”. Sa
ganito pong paraan, sasalain (filter) na lang ng mabuti ang mga waste water, tubig ulan at tubig galing sa kalsada sa
ating mga manholes, bago po ito makadating sa mga ilog at estero. Ito po ay maaring tawaging ”interceptor
wastewater treatment system”.
6) Kung sakali pong magkaroon ng ganitong ”interceptor waste water treatment system” sa inyong lugar, at sakaling
sisingilin kayo ng “user fee”, magkano po ang pinaka malaking halaga na inyong kayang bayaran buwan-buwan, para
sa proyektong ito? (Ang tanong po na ito ay para malaman ang ”maximum amount willing to be paid” o kakayahan
ng mga tao na makapag bayad para sa pag tatayo, operasyon and “maintenance” ng isang waste water treatment
system.)
Paki bilugan ang inyong sagot:
a) depende sa aking konsumo ng tubig; hanggang 50% ng aking bayarin sa tubig buwan-buwan
b) fixed na user fee, hanggang 20-50 pesos lamang buwan buwan
c) fixed na user fee, kaya hanggang 50-100 pesos buwan buwan
d) fixed na user fee, kaya hanggang 100 – 200 pesos buwan buwan
e) fixed na user fee, kaya hanggang 200 – 300 pesos buwan buwan
f) fixed na user fee, mahigit sa 300 pesos
g) iba pang halaga, pakisulat ang sagot ______________pesos
7) Sinong ahensya o kumpanya ang nais ninyong mangalaga at mag-asikaso ng ”waste water treatment system” sa
mga kanal at estero? Paki bilugan ang letra ng inyong sagot.
a) Maynilad
b) DPWH
c) MMDA
na kumpanya espesyalidad ang ”waste water treatment system”
d) DENR
e) isang bagong pribado
Maraming Salamat po sa inyong pakikiisa sa survey. Sana po ay maging matumpay ang layunin ng inyong komunidad
at mapalinis po natin ang ating mga kanal at estero. Salamat pong muli!
Gumagalang,
Trina Listanco, Estudyante (Royal Institute of Technology, Stockholm, Sweden)
(Residence) 13 Viola St. U.P Diliman, Quezon City
21
A P P E N D I X XIDrawings
1.
Manila, Estero de Valencia (EDV); In-line RBC Wastewater Treatment – Typical design for 7-2-2 Series I; Scale = 1:100; Size: A3; RBC-T1
2.
Manila, Estero de Valencia (EDV); In-line RBC Wastewater Treatment – Typical design for 7-2-2 Series II; Scale = 1:100; Size: A3; RBC-T2
3.
Manila, Estero de Valencia (EDV); In-line RBC Wastewater Treatment – Other Layouts; Scale = 1:150; Size: A3; RBC-T3
22
1/9
InEx :=
InputVarNEW3.xls
1
2
3
4
5
6
7
InEx = 8
9
10
11
12
13
14
15
16
17
1
"Lateral #"
"NL 50"
2
"Manhole #"
114
"NL 51"
"NL 49"
77
60
"Outfall02"
"NL48"
"Outfall05"
"Outfall09"
"Outfall06"
"Outfall07"
"Outfall08"
"NL 53"
"NL 54"
205
177
77
60
"Outfall02"
8
"Outfall05"
"Outfall09"
"Outfall06"
"Outfall07"
"Outfall08"
251
230
〈3〉
Qa := InEx
i := 15
3
m
Q := Qa ⋅
i day
3
"Q (m^3/day"
8.744·103
8.409·103
2.304·103
2.629·103
3.744·103
903.661
9.853·103
2.508·103
8.727·103
3.35·103
1.706·103
3.159·103
4.794·103
1.555·104
4
"BOD (g/m^3)"
38.147
25.875
35.296
30.116
33.65
28.164
31.097
31.133
36.659
33.446
31.128
30.456
32.592
27.568
〈5〉
TKNa := InEx
〈4〉
BODa := InEx
g
TKN := TKNa ⋅
i 3
m
g
BOD := BODa ⋅
i 3
m
5
"TKN (g/m^3)"
11.649
8.48
17.884
5.418
6.775
16.603
11.58
10.77
9.847
14.495
14.875
7.048
10.921
12.739
6
2/9
Combined BOD Removal and Nitrification Trickling Filter
0. Input values
3
Q = 15553
TKN = 12.7
m
day *
g
g
BOD = 27.6
3
3
m
m
Filter depth:
depth := 6.1m
Density of packaging material:
DensPack := 100
2
m
3
m
BOD ⎞
1. Determine the specific TKN removal rateRn := 0.82⋅ ⎛⎜
⎝ TKN ⎠
2. Determine the TKN removal
− 0.44
g
⋅
m ⋅ day
TKNrem := 0.9⋅ Q⋅ TKN
3. Determine the required surface area of packing As :=
FilterArea :=
q :=
3
Vol
2
FilterArea = 501 m
depth
Q
q = 0.36
FilterArea
a. Loading based on volume
1kg
1000g
Vol
BODloadingV = 0.14
kg
3
m ⋅ day
b. Loading based on area
1
⎛
⎞ ⋅ 1000 g
BODloadingA := BODloadingV⋅ ⎜
kg
⎝ DensPack ⎠
BODloadingA = 1.404
7. Determine the volumetric oxidation rate
g
So := BOD
So = 27.568
NOx := 0.9⋅ TKN
NOx = 11.465
VOR :=
(So + 4.6 ⋅ NOx)⋅ Q
Vol⋅ 1000
g
kg
3
m
g
3
m
VOR = 0.409
kg
3
m ⋅ day
L
2
m ⋅s
6. Determine the BOD loading based on volume and surface area
BODloadingV :=
day
Vol = 3054 m
DensPack
To meet the minimum hydraulic application given previously as 0.5 L/m^2*s recirculation will
be required.
Q⋅ BOD
g
2
As
5. Determine the hydraulic application rate
m ⋅ day
As = 305423 m
Rn
Vol :=
g
2
TKNrem = 178314
TKNrem
4. Determine the volume of packing material
Hydraulic application rate, q
Rn = 0.584
2
g
2
m ⋅ day
3/9
Computation for BOD removal
1. Determine k20 for design conditions (WEF 2000)
0.5
⎛ L⎞
⎜
⎝s⎠
k1 := 0.210
2
0.5
D1 := depth
D2 := depth
m
S1 := 150
⎛ D1 ⎞
k20 := k1⋅ ⎜
⎝ D2 ⎠
g
3
m
0.5
⎛ S1 ⎞
0.5
⋅⎜
⎝ So ⎠
⎛ L⎞
⎜
⎝s⎠
k20 = 0.49
2
m
0.5
Correction for temperature effect (Matcalf and Eddy, 2003, p917) k28 := k20⋅ 1.035
28− 20
⎛ L⎞
⎜
⎝s⎠
k28 = 0.645
2
2. Determine the effluent BOD concentration
m
− k28⋅ D 2
Se
So
=e
q
0.5
Se = 0.039
g
3
m
3. Determine the recirculation rate and recirculation ratio
The minimum wetting rate: Wr := 0.5
Determine the recirculation ratio
4. Pumping rate
L
2
m ⋅s
R :=
Dow Chemical (WEF, 2000), page 919 - Metcalf and Eddy 2003
q + qr = Wr
qr
q
Pr := Wr⋅ FilterArea
R = 0.391
qr = 0.14
L
2
m ⋅s
L
Pr = 250.346
s
5. Determine the rotational speed
3
R = 0.391
q = 1.294
m
A := 2 number of arms
2
m ⋅ hr
DRn := 10mm
DRf := 200mm
DR: Dosing Rate
nn :=
nf :=
( 1 + R) ⋅ q
A⋅ DRn
( 1 + R) ⋅ q
A⋅ DRf
1
nn = 1.5
min
rotational speed - normal dosing
1
nf = 0.075
min
rotational speed - flushing
4/9
Determine trickling filter airflow rate requirements and pressure drop
for forced ventillation
Input values
3
Wastewater flowrate:
Q = 15553
Primary effluent:
BOD = 28
m
Temperature:
day
g
T := 28K
So := BOD
3
m
Design assumptions
BOD loading:
BODloadingV = 0.14
Organic loading peak factor:
3
kg
LB := BODloadingV⋅
3
m ⋅ day
kg
Tower diameter, calculated from the filter area:
⎛
⎜
d := round⎜
⎝
⎞
FilterArea
depth
π
⋅
1
m
, 1 ⋅m
⎠
nd := 1
depth = 6.1 m
Depth of packing:
Headloss correction factor for inlet and other minor losses:
Lin := 1.5
Headloss correction factor for cross-flow packing:
Lcross := 1.3
Air temperature:
Tmin := 18K
Tmax := 38K
Solution
1. Determine the required oxygen rate
Ro := 20
kg
kg
⎛
⋅ ⎝ 0.80 ⋅ e
− 9⋅ LB
+ 1.2⋅ e
− 0.17 ⋅ LB⎞
⎠ ⋅ PF
Ro = 45.849
2. Determine airflow rate for the given conditions
a. Determine the airflow rate at standard conditions
3
ARSTD :=
Ro⋅ Q⋅ So⋅ 3.58
g
1000
kg
⋅ 1440
m
3
m
ARSTD = 48.875
min
kg
min
day
b. Correct the air flowrate for temperature and pressure
⎛ 273.15K + Tmax ⎞
273.15K
⎝
⎠
ART := ARSTD⋅ ⎜
3
m
ART = 55.674
min
c. Correct the air flowrate for lower oxygen saturation
⎛
Tmax − 20K ⎞
⎝
100K
AR := ART⋅ ⎜ 1 +
⎠
LB = 0.14
same as flowrate peak factor
PF := 1.64
Number of towers:
m ⋅ day
3
AR = 65.695
m
min
kg⋅ O2
kg⋅ BOD
d = 26.1 m

COMBINED STORM AND WASTEWATER TREATMENT

Transcription

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