Towards a more sustainable wastewater handling in the

Towards a more sustainable wastewater
handling in the municipality of Cedry
Wielkie, Poland
-A case study of the sanitary situation in the rural community of Trzcinisko,
Eastern Pomerania Region
Author:
Linda Wolski
Master Thesis, 30 ECTS
Department of Environmental Science
Lund University
Supervisors: Lars Nerpin
Åsa Blixte
1
Abstract
With almost its entire surface belonging to the Baltic Sea drainage basin, Poland with its 40
million inhabitants has a large impact on the eutrophication of the Baltic Sea. Several large-scale
measures have been proposed to decrease the nutrient leakage to watersheds and the coast.
However, a large proportion of the Polish population lives in rural areas that lack connections to
central wastewater treatment.
This thesis seeks to describe the wastewater practises in a Polish rural community by the Baltic
Sea, and furthermore, to give proposals on solutions that would favour a more sustainable
wastewater handling according to the joint agreement set out by the Helsinki Commission in
2007 and signed by the aligned countries.
A questionnaire handed out to the households in the studied community showed that the most
common system for wastewater handling is a “sealed” cesspool that is emptied on a regularly
basis. Estimations indicate that cesspools are commonly leaking. Since a connection to the central
wastewater treatment plant is considered a too costly investment, local authorities are seeking a
proper solution for on-site wastewater treatment for the studied object. The thesis describes
possible alternatives chosen according to the rather complicated local conditions with a high
groundwater level and dense organic soils.
Alternatives at the source include separate grey- and black water handling by the use of a vacuum
flush toilet connected to an outdoor compost. Other proposals include an ordinary water closet
with a coarse separation unit, urine-separating dry systems, as well as separate black water
collection through ultra-low flushing toilets.
Alternatives at the end of the pipe are wetland-and root zone treatment systems, premanufactured vegetation filters and sealed willow plantation filters. All of the mentioned
proposals have been tried out in different contexts in Sweden and Denmark.
All of the proposed solutions might not be suitable for the entire community. Instead, the
intention is that at least one of the proposals should suit any of the households. Ultimately, the
largest effort needs to be put into an active dialogue between locals, authorities, entrepreneurs
and manufacturers. The above presented solutions have shown to be successful predominantly in
communities with a high degree of local interest and participation.
2
Table of contents
List of abbreviations and definitions................................................................................... 4
1. Introduction..................................................................................................................... 6
1.1 General overview ...................................................................................................... 6
1.2 Aim of the study........................................................................................................ 7
2. Background ..................................................................................................................... 9
2.1 The Baltic Sea eutrophication................................................................................... 9
2.2 Poland’s national contribution .................................................................................. 9
2.3 Legal background.................................................................................................... 10
2.3.1 European legislation and the Polish national implementations ....................... 10
2.3.2 The HELCOM Recommendations and the Baltic Sea Action Plan................. 11
2.3.3 Polish National legislation ............................................................................... 14
2.3.4 National classification of surface and groundwater......................................... 15
2.4 The wastewater handling in Polish rural households.............................................. 15
2.5 Structure and sanitary situation of the Cedry Wielkie municipality....................... 16
2.6 The local soil structure, hydrology and ecosystem................................................. 18
2.7 The biological and chemical composition of domestic sewage water .................... 21
2.7.1 Bacteria and viruses ......................................................................................... 21
2.7.2 Phosphorous and the importance of P circulation............................................ 21
2.7.3 Nitrogen and the importance of N circulation ................................................. 21
3. Methodology ................................................................................................................. 23
3.1 The Lake Hornsjön-method (HS) ........................................................................... 23
3.2 Open Wastewater Planning (OWP) ........................................................................ 27
4. Results........................................................................................................................... 28
4.1 Classification of Trzcinisko sewage systems according to the HS- method .......... 28
4.1.1 General information gained from the questionnaire ........................................ 28
4.1.2 Final classification of the sewage system according to the HS-method.......... 29
5. OWP as a method for suggesting a new sewage system in Trzcinisko ........................ 31
5.1 Problem identification............................................................................................. 31
5.2 Identification of boundary conditions..................................................................... 31
5.3 Terms of requirements ............................................................................................ 32
5.4 Analysis of possible solutions................................................................................. 33
5.4.1 Alternatives at the source................................................................................. 33
5.4.2 Alternatives at the end of the pipe ................................................................... 38
6. Discussion ..................................................................................................................... 46
6.1 Methodology ........................................................................................................... 46
6.2 Results..................................................................................................................... 47
6.3 General conclusions ................................................................................................ 48
7. References..................................................................................................................... 50
7. Appendices.................................................................................................................... 54
3
List of abbreviations and definitions
Black water
Wastewater of domestic origin containing human excreta
BOD
Biological Oxygen Demand- Measure of the amount of oxygen in
consumed by microbes during the decomposition of organic
matter
Catchment area
A portion of land drained by a river and its sub-flows
Cesspool
Covered tank for collection of household sewage water
COD
Chemical Oxygen Demand- Measure of the amount of organic
matter oxidized by a strong chemical oxidant
HELCOM
The Helsinki Commission- Governing body for the 1992
convention signed by all the countries bordering on the Baltic Sea
and by the European Economic Community
Grey water
Wastewater generated through domestic water-consuming
activities such as laundry, washing and dish-cleaning
MWWTP
Municipal wastewater treatment plant
OWP
Open wastewater planning - a tool for sustainable sewage systems
P.E.
Person equivalents
Polder
Low-lying reclaimed land enclosed by embankments
River basin
See Catchment area
RZGW
Regionalny Zarząd Gospodarki Wodnej - The Regional Water
Management authority
Stabilized sludge
Sludge that has undergone a degradation process where the
organic content has been metabolised under aerobic or anaerobic
conditions
SIDA
Swedish International Development cooperation Agency
4
WFD
The EU Water Frame Directive
WIOŚ
Wojewódzki Inspektorat Ochrony Środowiska- The Regional
Inspectorate for Environmental Protection
Currency conversion used in this report
1 EUR (€)= 3.3 PLN =9.17 SEK (Riksbanken, 2008)
5
“Waste is merely an unutilized resource,
which can be better put to use, if handled correctly”
1. Introduction
1.1 General overview
One of the most efficient ways to reduce nutrient leakage to the Baltic Sea has been
considered for a long time to be the reduction of contaminants through construction and
modernisation of municipal wastewater treatment plants (MWWTP:s) in Central- and
Eastern Europe (Ollikainen & Honkatukia, 2001). The main reason, it is argued, is that
these countries still have a high potential for improving their wastewater treatment
systems at a considerably lower cost than is the case in for example Sweden where large
investments in sewage treatment systems already have been made (Elofsson, 2007).
Nevertheless, a significant proportion of the population within the Baltic Sea catchment
area is not connected to any public sewage system. In Sweden, that percentage is
estimated to around 10% of the population. This considerably low percentage stands for
as high as 50% of the total amount of eutrophying pollutants released from Swedish
household sewage to water (Avloppsguiden, 2007). In 2005, 40% of the population in
Poland was not connected to any municipal wastewater sewers (Eurostat, 2008).
One of the challenges in this concern is that a high proportion of the Polish population
live in rural regions. Out of a total population of 40 million, 38.5% live in settlements
with fewer than 2000 inhabitants (Bodík & Ridderstolpe, 2007). In fact, the total
contribution of contaminants from local sewage systems in Poland remains largely
unknown (Smołka, 2008).
The importance of accurately working sewage systems cannot be neglected from a health
nor, environmental perspective. In protecting the Baltic Sea from further eutrophication
as well as reaching the goal of the EU Water Frame Directive (WFD 2000/60/EC) - to
achieve a good water status in all water bodies by 2015, it is of major importance to
improve not only the sanitation systems of larger cities, but also to upgrade the sewage
handling in smaller communities that lack economical or structural resources to connect
the wastewater to a larger and technically more sophisticated system. The coastal and the
river-boarding regions of Poland play an important role in this context, since the effluents
- from especially the Vistula river are some of the main contributors to the emissions of
oxygen-demanding substances, phosphorous and nitrogen into the Baltic Sea basin
(Eriksson et al 2007).
6
This study has been carried out in cooperation with the environmental business network
Sustainable Sweden Southeast and the environmental consultancy company Vatten och
Samhällsteknik, both situated in Kalmar, Sweden. A significant part of their technical
know-how and environmental expertise lie within the field of wastewater management.
The cooperation has been based on an exchange of knowledge within the field of
wastewater treatment. Several small actors within the water treatment arena are interested
in the sanitary situation in Polish rural households. One reason for this is the large
financial support of 100 billion Euros that the country is given from the EU to improve
infrastructure and to raise environmental protection (SBHUB, 2006). An efficient
wastewater management is seen as a major need in this context and the Polish
municipalities receive considerable financial support from the EU to improve their
wastewater handling even at a local level in smaller communities (NEFCO, 2007).
Cedry Wielkie with its 6150 citizens is situated in the Pruszcz Gdański region, south of
the coastal city of Gdańsk. Cedry Wielkie is one of the municipalities that invests in the
construction and improvement of local wastewater systems. As an initial step, the
municipal wastewater treatment plant (MWWTP) has been upgraded to meet EU
standards and the wastewater grid is continuously connected to more communities. Prior
to the modernisation of the MWWTP the total length of the communal sewers was 18
kilometres and the plan is to extend the sewers with 14.4 kilometres by 2010. The total
cost for modernisation and upgrading of the treatment plant, sewers and on-site treatment
systems is estimated to €1 million of which 75% is financed by the EU (Cedry Wielkie
municipality, 2007).
Nevertheless, some communities are rather remotely situated and a connection to the
MWWTP would be very costly. Instead, the local authorities wish to find suitable
solutions that would meet emission standards while still being cost efficient. Also on-site
solutions are to be subject to EU financial support. Cedry Wielkie municipality has
agreed to a 50% cost replacement if landowners wish to install a new wastewater
treatment system (P.C; Goliński, 2008). From the Pruszcz Gdański region there is a large
interest in how local wastewater handling is carried out in Sweden since the Swedish
systems are believed to hold a long tradition of well-developed technologies.
1.2 Aim of the study
The aim of this study is to describe and classify the present wastewater practises in the
rural community of Trzcinisko and thereafter give proposals on solutions that would
reach the agreed reduction limits that were set up by the Helsinki Commission
(HELCOM). The proposals are to be based upon local, natural, social as well as
economic conditions and requirements. More specifically, this means that the following
aspects will be taken into consideration:
7
•
•
•
natural conditions such as geology, rivers, groundwater levels and the surrounding
ecosystem
social circumstances such as user acceptance and reliability
economic conditions, meaning affordability both for the users as well as for local
authorities.
In order to clarify the complexity around wastewater handling, the current legislation on a
national as well as a European level is taken into consideration throughout the study.
The reason for choosing the HELCOM Recommendations on reduction targets in this
project is that these targets are set out from what scientists have realised as the theoretical
maximum load of pollutants that the Baltic Sea can take and still hold a “good
environmental status”. The objectives of such a status are quoted and defined as follows
(HELCOM, 2007):
•
•
•
•
•
Nutrient concentrations close to natural levels
Clear water state
Natural level of algal blooms
Natural distribution and occurrence of plants and animals
Natural oxygen levels
The HELCOM has set up a number of reduction targets for each country and for different
sources of pollution. The reduction targets for on-site wastewater treatment of single
family homes, small businesses and settlements up to 300 P.E. (HELCOM
Recommendation 28E/6) are to be fulfilled by 2018. In perspective of the largely
insufficient treatment that is found in rural households around the Baltic Sea, it is of
major importance to enhance a more sustainable handling of the wastewater by stating
examples of good practices that might be followed and brought about on a larger scale so
that the jointly signed HELCOM targets for small-scale treatments can be reached in
time. It is my hope and intention that the suggestions in this study might serve as one out
of many practical examples of how future reduction agreements could be reached by
using more sustainable treatment technologies.
8
2. Background
2.1 The Baltic Sea eutrophication
This study is not intended to give an in-depth knowledge of the problems and causes of
the Baltic Sea eutrophication. Therefore, only a very brief summary of the eutrophication
problem is given in this and the following section. For further information on this
complex issue, see related links from e.g. HELCOM.
One of the main environmental concerns in the Baltic Sea is eutrophication. This
environmental disturbance is caused by largely excess inputs of organic matter, nitrogen
and phosphorous which leads to a higher primary production. The main sources for these
pollutants are agriculture, industries and insufficiently treated sewage water. The excess
of pollutants leads to an abnormally high primary production and eventually generates a
large-scale bacterial decomposition of organic matter. The intense decomposition is
highly oxygen-demanding and finally results in a lack of oxygen on the sea floor
(Brenner et al, 2007). Due to natural circumstances, the Baltic Sea has a low water
exchange rate, and is therefore additionally sensitive to eutrophication. The low water
exchange means a lower input of oxygen rich water that could counteract some of the
effects of eutrophication by increasing the oxygen content on the sea floor (Brenner et al,
2007).
2.2 Poland’s national contribution
A total of 99.7 % of the Polish territory is situated within the Baltic Sea drainage basin.
The country is inhabited by about half of the entire basin’s human population. Around
40% of the total amount of farmland within the Baltic Sea catchment area is situated in
Poland (Kowalkowski & Buszewski, 2006). With a background in these facts, it is
obvious that Poland stands for a large proportion of the river transported contaminants to
the Baltic Sea. The nitrogen effluents from the Vistula river stands for 1/6th of the total
riverine nitrogen entering the Baltic Sea (Eriksson et al, 2007). The Polish P emissions
are by far the highest compared to the other countries within the Baltic Sea drainage
basin. The largest part of the Polish P emissions originates from MWWTPs, followed by
surface runoff in which local (i.e. non-MWWTP) wastewater leakage is included.
Nevertheless, there is no specific figure on to what extent the local sewage contamination
contributes to the total contamination from surface runoff (Smołka, 2008).
9
2.3 Legal background
2.3.1 European legislation and the Polish national implementations
An important obligation concerning wastewater handling is the European Directive
271/91/EEC that demands the construction and functioning of a wastewater treatment
plant with biological treatment for all population agglomerations of more than 2000
inhabitants, by the year of 2015 (Bodík & Ridderstolpe, 2007). Even though communities
with less than 2000 inhabitants do not have any EU-implemented legally binding
obligation concerning sewage treatment, the Water Frame Directive (WFD) still obliges
all the EU25 countries to achieve a good water status in all water bodies by 2015
(Smołka, 2008). A good water status however, in many places seems very difficult to
achieve without improving the local sewage practises. The WFD target should be reached
throughout the use of a river basin approach, which in Poland has resulted in an eight-unit
river basin area division that is shown in fig. 1 below.
Fig. 1. The eight-unit division of river basin districts in
Poland (Ramowa Dyrektywa Wodna, 2006).
Fig. 2 shows the division of sub-districts within
the Dolna Wisła water district. (RZGW, 2006)
The Cedry Wielkie municipality is situated in the Dolna Wisła (Lower Vistula) water
district which includes the city of Gdansk and is marked in yellow stripes in fig. 1. The
Lower Vistula river basin district is managed from the regional office of RZGW- the
regional water management authority that is situated in Gdańsk (RZGW, 2006).
The Dolna Wisła water district is in turn divided into 21 sub-districts. Cedry Wielkie
municipality belongs to sub-district number 14 called the Martwa Wisła- Przymorze
Delty Wisły district (RZGW, 2006). The sub-district division can be seen in fig. 2. The
figure shows also how the Dolna Wisła main district is distributed over the three
10
Voivodships (red, bold lines) of Pomorskie, Warmińsko-Mazurskie and KujawskoPomorskie. The main functions of RZGW are to assure a good drinking water quality,
prevent water pollution and to protect the land from flooding and draughts. Other tasks
include water maintenance for the industry and water sport activities as well as river and
channel management for the state (RZGW, 2006). The organisation is thereby
responsible for setting restrictions on land use in order to protect the Vistula River and
the groundwater from polluting activities (Przewoźniak et al, 2004).
The Sewage Sludge Directive
Even though EU legislation does not include any regulations for wastewater treatment in
agglomerations with less that 2000 P.E., the Sewage Sludge Directive 86/278/EEC still
regulates the use of sludge originating from single households/ on-site treatment
facilities. The sewage sludge directive seeks to promote a sustainable use of the sludge in
agriculture while preventing contamination of the vegetation, soil, animals and man. One
of the principles is that untreated sludge needs to be injected or incorporated into the soil
in order to prevent local contamination. Treated sewage sludge is defined as “having
undergone biological, chemical or heat treatment, long-term storage or any other
appropriate process so as significantly to reduce its fermentability and the health hazards
resulting from its use". In order to prevent the spreading of pathogens, sludge may not be
applied to fruit or vegetable plantations during the fruit season or within 10 months prior
to harvest. Moreover, both grazing animals and harvest of forage crops is prohibited on
land where sludge has been applied within the last three weeks. The sewage sludge
directive further requires that the sludge be used in a way that meets the nutrient demands
of the plant in order to protect the soil and groundwater from contamination (Bodík &
Ridderstolpe, 2007).
The Eco-label regulation
The Eco-label regulation (EC) No 1980/2000 prohibits the use of sewage sludge in the
production of eco-labelled agricultural products. The regulation only applies for
producers that wish to retail eco-labelled products but it implies a large obstacle for
farmers who wish to use sewage sludge on their eco-label farmland. However, there is an
ongoing discussion on whether source separated toilet waste should be considered as
sewage sludge. If separated fractions of faeces and urine are not considered to be sewage
sludge there is, at least according to the Eco-label regulation, no legal obstacle for using
these fertilisers in Eco-labelled production (Bodík & Ridderstolpe, 2007).
2.3.2 The HELCOM Recommendations and the Baltic Sea Action Plan
In November 2007, the Baltic Sea countries signed an agreement that mandates countryspecific reduction levels of phosphorous and nitrogen (HELCOM, 2007a). The Helsinki
Commission estimates that, in order for the Baltic Sea to achieve a good environmental
status, the total annual input of phosphorous should not exceed 21,000 tonnes. The
corresponding limit for nitrogen is set to 600,000 tonnes. The average annual input 199711
2003 was 36,000 tons of P and 737,000 tons of N. In order to reach the necessary
reduction to achieve a good environmental status, the annual input of P should be reduced
by a 15,000 tons and N by 135,000 tons, see table 1 (HELCOM, 2007).
Table 1. The maximal allowable nutrient inputs in the Baltic
Sea as related to the actual inputs and needed reductions
according to the Helsinki Commission (HELCOM, 2008).
Maximum allowable
nutrient input (tonnes)
Inputs in tones 19972003 (normalised by
hydrological factors)
Necessary reductions
(tonnes)
Phosphorus
Nitrogen
Phosphorus
Nitrogen
Phosphorus Nitrogen
21,060
601,720
36,310
736,720
15,250
135,000
Poland carries a large part of the reduction requirements by being obliged to reduce its
annual P emissions by 8,760 tons and N by 62,400 tons. In order to reach these targets,
each country should by 2010 develop its own national strategies. It is eventually up to
each country to set the frames for a cost-efficient reduction.
The Helsinki Commission has suggested a few solutions that would theoretically make a
large difference to the total input. For example, increasing the phosphorous removal in all
MWWTPs from 80% to 90% together with the removal of phosphorous in detergents,
would together sum up to a reduction of phosphorous of more than 7,000 tonnes, which
corresponds to almost half of the necessary emission-cut for phosphorous (HELCOM,
2007a). Another important measure would be to reduce the contamination from large
animal farms that today stand for a continuosly increasing nutrient load. The construction
of sealed manure containers is here recommended as a very cost efficient solution, if
looking at the Baltic Region as a whole (NEFCO, 2007).
This tells us that a top-down solution is necessary for an efficient reduction, but it is, in
fact, far from enough. In order to reach the set goals, measures have to be taken also from
a bottom-up perspective, meaning that resources have to be put into more efficient
reduction even on a small scale basis, including measures on a single household level
(Bodík & Ridderstolpe, 2007).
One of the main tasks of the Helsinki Commission is to provide recommendations on
measures to deal with specific areas of environmental concern. The HELCOM
Recommendations are to be implemented by the associated countries through their
national legislation.
12
The HELCOM Recommendation 28E/6 of 15th November 2007 is targeted towards single
family households in agglomerations of less than 300 P.E. and out of reach of municipal
wastewater pipelines- stating the following:
1) “Untreated wastewaters shall not be led directly to natural water systems in areas that
are not connected to sewers”
2) “Wastewaters from single family homes, small businesses and settlements should be
treated so that emissions per capita do not” exceed the values stated in table 2 below.
Table 2 shows the highest permissible load in grams/person/day (g/p/d) and the
approximate corresponding reduction percentage according to the HELCOM
Recommendation 28E/6 for single family households (HELCOM, 2008)
Parameter
Specific
pollutant load
in untreated
wastewater
(g/p/d)
Highest
permissible
pollutant load
after water
treatment
(g/p/d)
Normal
approximate
reduction
(%)
Approximate
reduction
sensitive
areas
(%)
BOD5
40.0
8
80
95
Tot-P
1.1
0.65
70
90
Tot-N
12.9
10
29
29
* The calculations are based on the Polish average water consumption of 100 l/p/d.
The HELCOM Recommendation 28E/6 further recognises a diverse need for wastewater
treatment depending on the sensitivity of the recipient. In more sensitive areas, an
enhanced reduction of BOD and phosphorous of 95% and 90% respectively, is necessary.
The recommendations concerning agglomerations up to 300 P.E. are to be implemented
in the signatory countries until 2018 (HELCOM, 2007b).
13
2.3.3 Polish National legislation
The following environmental-political goals, of which some are EU-implemented, are to
be fulfilled in Poland by 2010 (Stan Środowiska w Polsce, 2004)
•
•
•
•
•
•
Prolongation of measures taken for rational water consumption patterns
Reduction of groundwater usage for industrial processes
Achieve a good water status for all water bodies by 2015
Achieve a minimum of 75% reduction of organic substances in the catchment area
of the rivers Oder and Vistula.
Construction, modernisation and improvement of MWWTP:s
Reduction of polluting substances from point sources.
The Polish water law (Faolex, 2004) states the following in relation to water quality
regulations of private sewage systems:
“Sewage generated from a private household or farm can be released to the soil within
the borders of the own property only if the following criteria are fulfilled”:
1) The sewage volume does not exceed 5 m3/day
2) BOD5 is reduced by a minimum of 20% and suspended matter reduced by a minimum of 50%.
3) The sewage outlet is located above soil material with a minimum of 1,5 meter thickness to waterbearing groundwater layers.
Sewage generated from the private household or farm can be released to water devices
within the borders of the own property only if the following criteria are fulfilled:
1) The sewage volume does not exceed 5 m3/day
2) The sewage quality meets the set emission standards of outgoing water from MWWTP:s serving
2000-9999 P.E. (see table 3 below)
3) The highest water-bearing groundwater level is situated at a minimum of 1,5 meters below the
bottom of such a water device.
The outgoing water from MWWTPs serving 2000-9999 P.E. may not exceed the
concentrations or fall below the minimum reduction levels stated in table 3 (Faolex,
2004).
Table 3. Max. permissible concentrations or min. reduction levels in outgoing water from a
MWWTP serving 2000-9999 P.E. (Faolex, 2004)
Substance
BOD5
CODCr
Suspended matter
N-tot (Kjeldahl)
P-tot
Max. Concentration
25 mg O2/l
125 mg O2/l
35 mg/l
15 mg/l
2 mg/l
14
or a min. reduction of
70-90%
75%
90%
-
2.3.4 National classification of surface and groundwater
Poland has its own national system for classification of surface- and groundwater quality.
Basically, until 2004 the water quality was rated according to three different classes
based on a list of physical and chemical indicators. Within the first class belonged waters
that were suitable for human consumption or salmon aquaculture. Waters within this
class showed no or insignificant signs of human impact. The second class represented
waters that were pure enough for livestock consumption or water sport activities. Waters
belonging to the third class should only be used for watering of plant cultivations or
within industrial processes not demanding a high water quality. (Ministerstwo
Środowiska, 2004) The old classification system has been critisised for only being based
on chemical and physical parameters.
Since 2004, a new classification system for surface waters is used. The new system is
based on a five-degree scale for water quality assessment. The waters are classified
according to a combination of physical/chemical and biological parameters. The Regional
Agency for Environmental Control (WIOŚ) is responsible for monitoring surface water
quality (Ministerstwo Środowiska, 2004). The new classification system also includes an
assessment of the drinking water quality.
In 2002, WIOŚ carried out a series of analyses on the water quality in Martwa Wisła. One
of the collection points was located in Błotnik, a small community some half kilometre
south of Trzcinisko. For a period of time an increased concentration of suspended matter
was observed, which resulted in a classification of the water quality to fall within the
limits of class 3 (according to the old classification system). Nevertheless, seen on a
whole-year perspective, the water quality of Martwa Wisła met the standards for a class 2
position in the old classification system. The latest analysis series showed a “wellbalanced” microbial composition but a noticed increased concentration of Chlorophyll A
finally resulted in a class 2 classification.
2.4 The wastewater handling in Polish rural households
As of today, the most commonly used sewage system for Polish single family households
not connected by a pipeline to a municipal treatment plant, is to have a cesspool that
collects all of the sewage from the household, including grey water from washing,
dishing and showering. This cesspool is by rule of thumb emptied every 10-30 days by a
municipal car although this frequency varies largely due to different local sewage
practices. The collected content is typically emptied into a municipal sewage treatment
system, although this might not always be the case due to e.g. a lack of treatment
capacity. Sometimes illegal emptying takes place in a forest or other hidden site (Chmiel
& Pietrusiak, 2004).
Other disadvantages with this system involve the often leaking cesspools and commonly
far transportation distances, risk of soil/groundwater leakage as well as the unpleasant
15
odour during the relatively frequent collections (Chmiel & Pietrusiak, 2004). In general,
the frequent emptying and collection of wastewater involves expensive and air-polluting
transportation of highly diluted sewage where about 95% of the fluids consist of water.
Costs for cesspool emptying usually reach a level of € 3- 4.50 per cubic meter.
Depending on the size and the water consumption of the household, this cost could
generally vary from € 530 - 1030 per annum, presuming that the cesspool is sealed
(Kanalizacja i odwodnienie, 2007).
2.5 Structure and sanitary situation of the Cedry Wielkie municipality
The municipality of Cedry Wielkie is
situated in the western Żulawy delta
region and has a total of 6,150
inhabitants. The population is spread
out on 13 middle-sized or small
communities. The two largest
agglomerations include the
communities of Cedry Wielkie and
Cedry Małe which together host
around 2000 inhabitants. The smaller
rural communities count about 300
inhabitants each. (Cedry Wielkie
municipality, 2007)
A recently (2005) upgraded and
modernised wastewater treatment
plant serves the larger communities.
In total, about 2000 people are
connected, and by 2010 another
2000 people are to be served by the
MWWTP. Currently, a large
investment is made in order to
Fig. 3 shows the municipality of Cedry Wielkie (dashed
improve the communal sanitary
black line) with the modernized MWWTP (large red
standards and to meet EU
dot), the existing sewage pipelines (red full line) and the
regulations. An important part of the
planned sewage pipelines (dashed red line). (Cedry
investments involve the construction
Wielkie Woda, 2007)
of new sewerages in places which
were earlier not connected to the municipal wastewater pipeline, see fig. 3 (Cedry
Wielkie municipality, 2007).
At present, the sewage sludge is dried directly nearby the treatment plant and it is not
used as a soil fertiliser. The sludge quality has not yet been tested but the sludge isaccording to personnel at the treatment plant- assumed to contain very limited
concentrations of harmful substances, since it is only collected from households in a
rather sparsely populated area without heavy industries. However, sewage sludge has
16
occasionally been used as a soil amendment and fertiliser in the Cedry Wielkie
municipality. In 2003, sludge from the MWWTP Gdansk Wschód was applied as a
fertiliser on a property in Trzcinisko on a total area of 5.6 ha. In 2004, some sewage
sludge was used as a soil amender for local plant nurseries. The sludge handling was
carried out by the company Ekopolgrunt from Wrocław on demand from the water
management consulting group Saur Neptun Gdańsk. The local transportation company
Truck-Trans in Trzcinisko holds an official permission for transportation of stabilized
communal sewage sludge.
Some of the agglomerations in the municipality are rather scarcely populated and are
situated far enough away to make connection to the MWWTP a too costly investment.
One of these communities is Trzcinisko with 206 inhabitants (Cedry Wielkie
municipality, 2007). The distance from Trzcinisko to the closest planned sewage pipeline
in Błotnik is five km. Many houses are located several hundred metres from the nearest
neighbour while a few are more closely situated. Apart from earlier mentioned
complications, the land is also rather difficult for constructing sewers due to the heavy
soil as well as the many crossing channels and ditches in between the agglomerations.
As a part of the sanitary investments, an upgrade of the water grid has been carried out.
This resulted in a closure of most of the municipal water intakes due to high fluoride
concentrations. Many locals have been suffering from fluorosis and dental problems as a
consequence of the high fluoride content. Water for drinking purposes is nowadays
provided from three water intakes with concentrations that fall below the highest
permissible EU standards for fluoride in drinking water (Cedry Wielkie municipality,
2007). Since about ten years ago, the communal water grid also serves the Trzcinisko
community, although a few households still take water from a private well (P.C; Lech,
2008)
As in other parts of the country, the cesspool is the most common system for wastewater
collection in areas that lack a municipal sewerage. According to legal regulations, the
emptying of the cesspools should be carried out at least on an every-second-week basis.
In the case of the Cedry Wielkie municipality, the cesspools are emptied approximately
once a month, but there are several exceptions where emptying is carried out far less
frequently (P.C; Goliński, 2008). Currently, a collection point at the MWWTP in Cedry
Wielkie is used for collecting sewage from households that lack a communal pipeline.
According to personnel at the treatment plant, the input wastewater from cesspool
emptying contains a chemically more “aggressive” sewage than the sewage from the
communal pipelines. The bacterial composition is thought to be different from the one in
the sewage transported by communal pipelines. An employee working with this function
stated on a study visit in March 2008 that one reason could be that the sewage from
cesspools usually has been stored in anaerobic conditions for some period of time prior to
emptying, which leads to a deactivation of many microbes. As a consequence, the
cesspool wastewater is causing some disruptions in the biological activity at the treatment
plant.
17
2.6 The local soil structure, hydrology and ecosystem
The municipality of Cedry Wielkie is a characteristically agricultural region with 65% of
the area being arable land of very high quality for farming purposes (Piasek, 2002). After
decades of drainage-activities (dewatering practices have been carried out here since the
14th century), the soil has been increasingly exposed to air oxygen. This has led to an
increased decomposition of organic material into humus and as a consequence, a
lowering of the drained land (Strupińska, et al, 2001).
The Vistula river is one of the largest rivers entering the Baltic Sea and it has had an
immense impact on the geological structure that is found in the Cedry Wielkie region
today. Vistula runs from southern Poland and enters the Baltic Sea directly north of the
Cedry Wielkie municipality border. During its flow it carries immense amounts of eroded
soil materials containing nutrients and organic- and mineral particles which are deposited
at or near the river mouth as the water slows down.
Since large areas of the Żuławy region have been flooded either completely or
temporarily by the Vistula since the last glaciation, the soils contain large amounts of
fluvial deposits. These fluvial deposits are high in fine-particle organic matter (humus)
which gives the soil a very good water holding capacity. These organic soils are
considered to be very fertile but also rather heavy for farming practices (Strupińska et al,
2001). The high water-holding capacity also means that the ground is rather unsuitable
for treating sewage water by soil infiltration (P.C; Hammarlund, 2008).
The area in which we today find the Trzcinisko community was for a long period
between the last glaciation (11,000 years ago) and the 14th century partly or completely
covered with water, which is shown in fig. 4.
Fig. 5 shows the main watercourse in the
Żuławy river delta region of today. Although
smaller ditches are not presented on this map, a
comparison with fig. 4 gives a clear perspective
of the immense changes that have taken place
mainly as a result of drainage activities.
Fig. 4 shows the Żuławy river delta region on a
reconstructed map from the 14th century (Piasek,
2002). The thin dashed lines in the lakes mark the
approximate localization of the coastline of today.
Trzcinisko is marked with a red ring in both
maps.
18
The Trzcinisko community is situated directly on the southern shore of the Martwa Wisła or the
Dead Vistula river outlet. The Martwa Wisła enters the Baltic Sea about nine kilometres north of
Trzcinisko. This cut-off river basin was once the western path of the Vistula river delta. Since the
beginning of the 20th century it is chopped off from the main river and is nowadays regulated
with a sluice station a few kilometres east of Trzcinisko. This was done through the dredging of a
straight, broad channel north of the river, which formed the przekop Wisły, or the Vistula crosscut. The reason for this dig-out was to make available more of the flooded and thus highly fertile
land for crop production.
Martwa Wisła receives storm and drainage water from large parts of the Cedry Wielkie
municipality. The two main sources are the Śledziowy and the Piaskowy channels that together
collect water from the widespread smaller drainage ditches. The Śledziowy channel also receives
the treated wastewater from the MWWTP in Cedry Wielkie (Cedry Wielkie municipality, 2007).
The channels are embanked all along the course and pumping stations by the channel outlets to
Martwa Wisła are in charge of regulating the water flow. In the case of an increased water level
in Martwa Wisła, some watergates are closed in order to avoid flooding of the adjacent land
(Cedry Wielkie municipality, 2007). Polders have been constructed all over the Żuławy region
and now make up an important factor for land drainage. These low-lying constructed lands with
surrounding embankments are rather prone to flooding why it is considered to be of major
importance to maintain a good condition of the embankments and to not allow a too high
difference of the inside and outside water levels.
Fig. 6. View of Martwa Wisła as seen from the western shore in
Trzcinisko (Photo: private)
The ecological status of Martwa
Wisła (fig. 6) is altered by a number
of different sources of pollution. One
of them is a large pile of
phosphorous-cast, a waste product
from the fertilizer industry. The waste
is dumped at Wiślinka, right west of
Trzcinisko and the dumping site is
bordering the Martwa Wisła. Some
effort with Salix plantations has been
done to reduce the impact of the
storm water that is drained from the
pile to the Martwa Wisła, but the site
is still recognized as one of 14 water
polluting hotspots in Poland. (P.C;
Greenpeace, 2008)
The name Trzcinisko, denoting a reedy place, already tells something about the surrounding
environment. Common Reed (Phragmites australis) is frequently found along drainage ditches
and channels. Trees such as willow and alder are also rather numerous in this area with plentiful
groundwater. Avenues make up a distinct and unique element of this plane landscape. Besides the
avenues, many ditches and channels are also surrounded by various species of trees, i.e. birches
(Betula), poplar (Populus), ash (Flaxinus), lime (Tilia), maple (Acer), rowan (Sorbus) and beech
(Carpinus) which together make up an important habitat and migration path for many other
species (Cedry Wielkie municipality, 2007). Along with many other important ecosystem
19
functions, the vegetation zones around waterways also protect the water from nutrient leakage
from adjacent farming fields or other polluting activities (Tonderski et al, 2002). These ecological
buffer zones probably play an additional important role for protecting the water in the Żuławy
region since surface runoff is estimated to be rather high due to poor soil infiltration.
Due to its location by the Martwa Wisła, the groundwater level in Trzcinisko is rather high,
despite the open northward drainage ditches (fig. 7) that were once constructed to dewater the
land. At a distance of about 20 m from the shore, the groundwater level is according to villagers
estimated to maximum 50 cm below ground level. At the southern rear end of Trzcinisko, about 1
km south of this point, the groundwater level is most likely found at a level of two meters below
the ground. As a protection from flooding, a three meter high embankment of sandy clay has
been built along the Martwa Wisła.
Most of the groundwater is
found in marine sand aquifers
that were formed during the
Pleistocene interglacial period
or in sandy fluvial sediments
with overlying layers of clay,
mud and peat. The best aquifers
are found at a depth of 100 m
below the ground.
Replenishment of the aquifer is
taking place in the higher
situated lake lands of the
Żuławy district (Przewoźniak et
al, 2004). The aquifer is drained
in the lower coastal zones
surrounding the bay of Gdansk.
Fig. 7. One of the northward drainage ditches crossing Trzcinisko. The
Even though contamination of
water is discharged to Martwa Wisła where after a kilometer it finally
finds its way out to the Gdańsk Bay (Photo: private).
the deep groundwater aquifers
in Trzcinisko is rather unlikely,
there is still an obvious risk of contamination of the surface waters in Martwa Wisła. This risk is
linked to the dense grid of drainage ditches that easily transport discharged sewage from adjacent
land (Przewoźniak et al, 2004). The impermeable soil layers are likely to cause a high surface
runoff of contaminants that are easily discharged into the closest drainage ditch (P.C;
Hammarlund, 2008).
Due to the protective and rather impermeable layers above the main aquifers, there is no
officially restricted area of groundwater protection. The groundwater generally has a high
concentration of fluoride which in places exceeds the permissible standards for drinking water
(Cedry Wielkie municipality, 2007). For information on measures taken to solve this problem,
see section 2.3 in this report.
20
2.7 The biological and chemical composition of domestic sewage water
The main contaminants in sewage water from households come from urine and faeces where a
wide range of polluting agents can be found. Below is listed the most important considering
environmental as well as health risks.
2.7.1 Bacteria and viruses
These contaminants originate predominantly from faeces. The large amount of Coli bacteria in
faeces can, if untreated, lead to serious human infections. Disinfection of these pathogens can be
carried out through fermentation processes, soil infiltration/percolation, or by sterilization with
chlorine or UV-light radiation.
2.7.2 Phosphorous and the importance of P circulation
Phosphorous is released from the bedrock through the weathering process. It is eventually
transported through the soil where the phosphate ions (PO43-) easily forms conglomerates with
soil particles. Due to its rather insoluble properties, phosphorous is mainly transported from the
soil through plant uptake or surface particulate runoff. (Brady & Weil, 2002)
Phosphorous is today extensively extracted from phosphate mines for usage as an agricultural
fertiliser. Another source might be animal manure. Via human consumption of agricultural
products it is eventually extracted, with a large part finally ending up in the sewage water. It is of
great importance to recycle and reuse the phosphorous as it otherwise might end up in water and
sediments contributing to the eutrophication of smaller water bodies as well as the Baltic Sea.
This is also of major concern for the agricultural sector since phosphorous is a limited resource.
Once diluted in lakes and seas, it is practically impossible to extract and reuse as a fertiliser
(Johansson et al, 2002).
Phosphorous is more abundant in urine than in faeces. Slightly more than 50 % of the
phosphorous comes from urine; the rest comes from faeces and greywater, with about 25%
respectively, presuming that the household detergents contain phosphates. (Johansson et al,
2002). In other words, the major part, or at least 75 % of the phosphorous can be removed from
wastewater by source separation of urine and faeces.
2.7.3 Nitrogen and the importance of N circulation
Nitrogen is, unlike phosphorous, very abundant in the air. Around 80% of the air is constituted by
nitrogen gas. All organisms are dependent on nitrogen for their growth. However, most plants are
not able to use the nitrogen gas in the air for direct nutrient uptake. Instead, they rely on soilavailable nitrogen that appears as either ammonium, NH4+, or nitrate, NO3-. These molecules
have been made available for plant uptake through processes that we refer to as ammonification
and nitrification. The latter processes turn organically bound nitrogen into soluble and plant21
available ammonium and nitrate. Those chemical activities are carried out mainly by
microorganisms in the soil or water. Nitrate is recycled to the atmosphere by the process of
denitrification where bacteria in an anoxic environment convert the nitrate to nitrogen gas by
using the oxygen atom in nitrate for their metabolism (Persson, 1997).
However, nitrogen can also be fixated through artificial chemical processes which are carried out
on a large-scale basis for the production of nitrogen fertilisers. This synthetic fixation of nitrogen
is rather resource demanding since 1 kg of oil is required for producing 1 kg of nitrogen fertilisers
(LfM, 2006). As a consequence, it is from a natural resources perspective desirable to reuse the
nitrogen that was once derived from farmlands through human consumption.
The nitrogen cycle is a key function in wastewater systems since the natural nitrification and
denitrification processes can be synthetically stimulated to enhance the removal of nitrogen in
sewage waters. This is basically done by adding and removing the oxygen supply in MWWTP:s.
The dominant source of nitrogen in wastewater is the urine fraction that contains just over 80% of
the total nitrogen content. Faeces contain some 10% of the total nitrogen so by separating the
urine and faeces already at the source, nitrogen can be reduced by over 90% and the collected
nutrients can after proper storage be used on arable land since source separated toilet waste is a
rather pure fertiliser with very low content of heavy metals and other hazardous substances
(Swedish EPA , 1995).
In fact, 75- 90% of the phosphorous, nitrogen and potassium is found in urine or faeces, which
together only constitute about 1% of the total sewage flows (Swedish EPA , 1995). These figures
are dependent on consumption patterns such as the usage of phosphorous-based detergents in a
household.
22
3. Methodology
Two tools were chosen to fulfil the aim of this study. The two tools differ from each other in
several significant ways. The first, which is here referred to as the Hornsjön-method (HS), was
developed by the Swedish environmental consultancy group Vatten- och Samhällsteknik AB. The
HS method is based on technical and physical parameters such as sewage system performance,
distance to the closest water stream, groundwater level as well as soil structure and profile
(Larsson et al. 2005).
The second, Open Wastewater Planning (OWP) was carried out by another Swedish
environmental consultancy group, Water Revival Systems Ekoteknik AB in cooperation with
Swedenviro AB. The main objectives in OWP are to focus on the actual function of the
wastewater system instead of the technological approach that traditionally has been widely used
in wastewater planning (Kvarnström & af Petersens, 2004). OWP is an interdisciplinary tool for
sustainable water technology in the sense that it focuses both on the environmental, economic as
well as the social aspects of sustainability.
Initially, the HS-method was used to classify the existing sewage system in Trzcinisko.
The result of the HS-method was used as a basis for working with the Open Wastewater Planning
concept in which new wastewater practises were suggested for locals as well as for the
municipal- and regional authorities.
Below, a more thorough description of each methodology is given.
3.1 The Lake Hornsjön-method (HS)
The HS-method was developed as a tool for protecting local groundwater and surface waters but
also for realising a common tool for classification of on-site sewage systems. The method can be
used both for existing amenities as well as for planned constructions. In this study the focus is put
entirely on the existing systems.
The classification was based upon answers given in the specially prepared survey
“Questionnaire on the sanitary situation in Trzcinisko”. (See appendix A) The questionnaire was
distributed by the local authorities with the help of a community representative.
23
Initially, a classification based on the technical standards (fig. 8) was carried out. The studied
sewage systems were here defined as good, middling or poor. If the given information would be
too poor, the sewage system could not be classified, and would be marked as no classification. In
this case, a check-up through e.g. a phone call or a study visit is recommended in order to classify
the lacking amenities.
Fig. 8. Systematic scheme for classification of the technical standard of a sewage system according to the HSmethod (Larsson et al, 2005).
At a second step, the technical classification should be completed by adding site-specific
conditions, meaning that a technically good system could be classified as poor if the local soil
conditions are not appropriate for the existing system. An example would be a sand infiltration
system which usually is classified as good, but in an area with high groundwater levels, it would
be classified as poor since it would likely not serve its original purpose. In order to classify the
site-specific conditions, a credit-system is used which is shown in the following tables.
In order to classify the site-specific conditions, three main aspects were taken into consideration.
These aspects would not give a complete information of the local barrier effect but since they are
all of major importance, they are here used as an approximate measure of the barrier effect.
1. For assessing the transportation in the unsaturated zone the following schedule is used:
•
Unsaturated zone non-existing or less than 1 meter deep
0 credits
•
•
Unsaturated zone more than 1 meter deep
The facility is a closed system
1 credit
2. For assessing the transportation in the saturated zone the distance to closest water body is
taken into consideration as given below:
24
•
•
0-50 meters from source to closest surface water
Facility located on bare rock material or clayey till
0 credits
•
50-100 meters from source to closest surface water
1 credit
•
•
100-200 meters from source to closest surface water
The facility is an on-site wastewater treatment plant with biological and
chemical treatment
2 credits
•
•
More than 200 meters from source to closest surface water
The facility is a closed system
3 credits
3. For a simplified assessment of the decomposition and adhesion of pollutants in ditches
and water bodies, the following standards are suggested as a tool.
•
0-0,5 km of ditches or water courses between source and receiving water
This is supposed to correspond to an average retention time of one hour
0 credits
•
0,5-1 km of ditches or water courses between source and receiving water
This corresponds to an average retention time of two hours
1 credit
•
1-4 km of ditches or water courses between source and receiving water
This corresponds to an average retention time of up to eight hours
2 credits
•
More than 4 km of ditches or water courses between source and receiving
water. This corresponds to an average retention time of more than eight
hours.
3 credits
25
4. In order to make a final assessment of the barrier effect, the summarized credits from the
previous partial assessments are classified according to the schedule below.
Credits
Assessment
Measure
0-1
• Very poor barrier effect
• The facility should not be permitted.
• The facility is situated close to
surface waters.
• The facility should be relocalised to
improve the barrier effect or
additional requirements should be
set. Dry or closed systems are
recommended.
• There is no appropriate natural
purification of the outgoing
water.
2-3
• Poor barrier effect.
• The facility is situated
relatively close to surface
waters.
• Ditches or the ground provide
a limited barrier effect.
4-7
• Good barrier effect.
• The facility is situated at some
distance to surface waters.
• The site provides a
considerable barrier effect.
• Facilities with this location can be
permitted
• Additional purification should be
considered or the facility should be
relocalised to improve the barrier
effect.
• Facilities with this location can be
permitted
• No special measures needed to
improve the treatment function.
In order to classify the present sewage system in Trzcinisko according to the described HS–
method, the given cesspool volumes and emptying frequencies had to be related to a hypothetical
water usage. This was done in order to estimate if the cesspools were sealed or if there was an
assumed leakage, the latter leading to a direct classification as poor, whereas sealed tanks would
automatically be classified as good. To simplify the assessment, a theoretical water usage value
was calculated for each household, presuming that the cesspool was sealed. This was done by
multiplying the cesspool volume with the emptying frequency and finally dividing by the amount
of people in the household. The resulting value was then related to general published statistics on
100 l/person/day as the average national water usage which can be compared to the Swedish
average of 150 l/person/day (Bodík & Ridderstolpe, 2007b).
26
3.2 Open Wastewater Planning (OWP)
In this method a wide perspective approach is applied to define the needs and functions of a
wastewater system in a community. The general goal is to create a sustainable sanitation system
which is here defined as a system that promotes human health, prevents environmental
degradation and the depletion of finite resources (i.e. phosphorous) and that are economically as
well as socially acceptable by being for example user friendly and free from odours. In OWP, a
sanitation system is realised as something far beyond merely technology; the term also implies
the collection, transportation, treatment and usage of the end products such as sewage sludge,
urea or even biogas.
Throughout the planning process, a large importance is given to the stakeholders. Involving the
users, decision makers and possibly farmers already at an initial level will increase the probability
of a successful result since the stakeholders are given a sense of ownership in the investment. The
whole process is divided into five steps. Finally, to the stakeholders are proposed a few selected
alternatives which should all fulfil the initial terms of requirements. (Kvarnström & af Petersens,
2004)
Step 1: Problem identification
In this step it is recommended to use tools such as the Logical Framework Approach; however, in this
case, a questionnaire was sent out to the users as a tool for identifying the problem.
Step 2: Identification of boundary conditions
In order to limit the study, geographical, legal, social and environmental boundaries need to be set.
Step 3: Terms of requirements
A crucial part of the project involves the setup of system requirements. These should be established by a
facilitator together with the local authorities as well as the concerned community. The requirements
should include all the specifics for creating a site-appropriate and sustainable sewage handling. Usually,
the requirements are divided into two blocks where the first one describes hygienic standards to be
fulfilled, while the second block contains practical demands such as user-friendliness, reliability and
affordability. It is important to obtain a well balanced combination of the two blocks. There is no ready
measure of sustainability for a project; instead, it is recommended that each site be given the best
possible sustainability adapted solution according to the site-specific conditions.
Step 4: Analysis of possible solutions
It is recommended that at least three options for system solutions be presented for the stakeholders. The
presentation should include a comparison of the given options and should be based upon the Terms of
Requirements set in level 3. It is of major importance that the options are presented in an impartial and
neutral manner.
Step 5: Choice of the most appropriate solution
On this level the stakeholders and the system users should agree on which option to be most suitable for
their community. A suggested method is to give points to each parameter and use the summary to
eventually predict which of the options that best match the Terms of Requirements.
27
4. Results
As stated in the introduction section 1.2, the aim of this study is to classify the present sewage
system in Trzcinisko according to the HS-method and to give suggestions for a more sustainable
wastewater handling in the community by using the OWP-method.
4.1 Classification of Trzcinisko sewage systems according to the HS- method
4.1.1 General information gained from the questionnaire
The questionnaire resulted in a 76 % respondent frequency which was represented by 34
answering households, see fig. 9. The total amount of people living in the responding households
was 117.
All of the responding households turned out to be occupied on a year-round basis. All, with the
exception of three respondents, were using a cesspool for collection of all the water used within
the household. The cesspools were all emptied by a municipal car with a widely varying
collection frequency. In the households where no cesspool was installed, a dry toilet was used for
sewage collection and the content was emptied into nearby ground. According to the respondents,
no organised grey water separation or treatment was used. The same was true for urine
separation.
Fig. 9 shows the location of the responding households
The cesspools were, according to the given answers, of largely varying sizes with a volume span
from a few cubic meters up to twenty cubic meters.
28
Four of the households did not state the cesspool volume, the amount of people in the household
and/or emptying frequency, which made it impossible to classify their sewage system.
Five of the respondents used a private well. Three of these were drilled (households nr. 8, 13 and
20) and two (nr. 5 and 25) were dug. Some of the wells are according to villagers and authorities,
so-called artesian wells, meaning that the pore pressure is high enough to cause an upward water
transportation to the well without any necessity of pumping. This phenomenon appears if
groundwater is trapped in between two impermeable layers.
Four out of the five respondents with a private well stated the water quality as good and they had
no remarks on water colour, smell or flavour. One of the respondents with a private well (nr. 20)
did not comment on the water quality. However, it is unclear whether the local wells are used for
drinking water purposes since it is very common to purchase bottled water.
The remaining households were provided with communal water. Bad water taste and smell were
stated in four of these households. Six respondents remarked on the water colour being other than
neutral (rusty or yellow). Three of the households with communal water stated the water quality
as unpleasant all year round.
4.1.2 Final classification of the sewage system according to the HS-method
The three dry systems that were found in Trzcinisko would according to the HS-method be
classified as good.
Depending on the estimated water usage within the households, the cesspools were classified as
either good or poor, giving no room for a gradual assessment. As soon as a tank is suspected to
leak, the system will automatically be classified as poor irrespective of the size of the leakage. A
theoretical value is set on a water consumption level of 100 l/p/day which corresponds to the
average household water consumption in Poland (Bodík & Peter, 2007b). Taking into
consideration the amount of people in each household and the emptying frequencies, this would
mean that at least 21 out of the total 24 cesspools are leaking and would consequently be
classified as poor regarding the technical standard. For an illustration of the technically classified
sewage systems and the surrounding wells, see the classification map in appendix B.
When taking into consideration the site-specific conditions, i.e. the barrier effect, the results
varied only slightly. The households that were situated on ground with <0.5 m to the groundwater
were also closely situated to open surface water (<50m). All of the households were situated on
ground with very low hydraulic conductivity which could be compared to clayey till that is used
as a reference.
The technical classification of the dry toilet systems as good was changed after the barrier effect
was taken into consideration. The dry systems were all emptied into the ground, either directly, or
after a period of storage. All three dry systems were localized at a distance of less than 50 m to
closest surface water where groundwater levels were around 0.5 m. The sewage containers were
29
also emptied on the organic sediment soil with a very poor infiltration capacity. These facts
together added up to a total assessment of 0-1 credits which means a very poor barrier effect.
According to the applied classification standards, there is a very limited natural purification of the
outgoing water and hence, the facility should not be permitted. Alternatively, the facility should
be relocated or additional requirements should be set. The classification standards here
recommend that either dry or enclosed systems be installed.
30
5. OWP as a method for suggesting a new sewage system in
Trzcinisko
5.1 Problem identification
The questionnaire answers gave several indications of problems within the present sewage
system.
•
Six out of 34 respondents (17.6%) remarked their sewage system as unsatisfactory.
•
In 23 of the households (67.7%), bad odour was felt during cesspool emptying.
•
For ten of the households (29.4%) bad odour occurred not only during cesspool emptying.
•
Four of the respondents (11.8%) stated under “comments” that they aim to install a new
treatment facility that fulfils the set environmental standards.
•
None of the respondents had noticed any clear ecological changes that could be related to
sewage water leakage. Three of the respondents stated “I don’t know”.
In a meeting with the locals, a general anxiety was expressed about the actual aim of the sanitary
assessment. “Was this going to mean high investments cost for the local community?” and “Why
are the authorities interested in such local and private issues?” were comments that were heard
among the residents. Others were more interested in the study and the sudden focus that was set
on their community.
5.2 Identification of boundary conditions
In order to limit the extent of the study, a geographical boundary was set around the area of the
Trzcinisko community, secluding the nearby located village of Szerzawa. The legal boundaries
include national law, European Union regulations as well as the Recommendations that were set
by the Helsinki Commission in the Baltic Sea Action Plan. The social boundaries correspond to
the geographical boundaries by involving the inhabitants of the Trzcinisko community. However,
the social boundaries also reach beyond the responsible authorities of the Cedry Wielkie
municipality as well as the provincial authorities of Pruszcz Gdański since they have been
interested in the project since the start. The health and environmental boundaries involve the
protection from bacterial or viral infections as well as protection of the soil, groundwater and
inland waters and measures taken to reduce the Baltic Sea eutrophication. Nevertheless, due to
the set limitations, emissions of greenhouse gases from the sewage systems or the transportation
of sewage water are not taken into consideration in this study.
31
5.3 Terms of requirements
The following table 4 shows the Terms of Requirements that were set for achieving a more
sustainable wastewater handling in Trzcinisko. The requirements were chosen after a proposed
list from the OWP-system and after general opinions from the locals.
Table 4. Terms of requirements for a new sewage handling system in Trzcinisko.
Primary functions
Sanitation and disease prevention:
Secondary functions
Costs:
*odour neutralisation
*user-friendliness
*elimination of pathogens
Water protection:
*prevention of nutrient- and organic
matter leakage to ground and/or surface
waters
*Economically feasible both as an initial
investment as well as for long term
maintenance
Reliability:
*Locally available operational know-how
*Robust for high groundwater levels
Reach the HELCOM Recommendations with the
following reduction levels:
BOD5 95%
Tot-P 90%
Tot-N 30%
Natural resources conservation include
the management and saving of:
*water
*nutrients (the sludge would preferably
be used in local agriculture/private
gardens
*energy
The emission limits for water protection were stated in the HELCOM Recommendations 28E/6
for areas with a high ecological sensitivity. Due to the close location of the Martwa Wisła River
and the Baltic Sea, the highest protection level was chosen for Trzcinisko.
32
5.4 Analysis of possible solutions
5.4.1 Alternatives at the source
The most efficient way to reduce contaminants in sewage water is through source separating
systems. These systems also decrease the need for infiltration treatment that otherwise would
have been difficult to accomplish in Trzcinisko due to the unsuitable soil and groundwater
conditions. Another advantage with using a source-separating system is the saving in water
consumption. Even though freshwater might be plentiful at a site, the purification process still
implies a possibly chemical and energy-demanding and costly process. A possible option for
saving fresh water is to collect rainwater for flushing. A large effort has been made to develop
modern and convenient separating toilet systems. Below, some of the latest solutions from this
research field are presented.
The BioGlobe system for toilets
Function
This method has been developed during 12 years by researchers at SLU, the Swedish University
of Agriculture. It is based on a nearly dry toilet system with an extremely water saving vacuum
toilet consuming about 0,4 l of water/flush. The toilet is connected through a vacuum pump to a
compost system with manure worms in the top layer, see fig. 10. A small construction of robust
plastic serves as a cover. Organic kitchen waste can easily be composted through an opening in
the roof. The compost has a structure of liquid separating and aerating layers and the surplus
water is led to a root zone infiltration area before it is finally discharged into the closest ditch.
The root zone can consist of either natural vegetation like trees and shrubs but can also be planted
with perennials, berry bushes, etc. The length of the root zone should be 15 m.
Fig. 10. The BioGlobe compost with its drainage layers. Sludge is applied
from the vacuum pipe to the top and is drained by a layer of leca, followed
by a layer of washed sand. The bottom is covered with a geotextile
(BioGlobe, 2007)
33
Reduction and recycling
potential
The manure worms in the
compost assure a high and
fast decomposition of the
organic matter. Solid waste
is rapidly turned into a soil
amender that can soon be
used in the garden. In order
to separate the fresh and
decomposed matter, a wall
can be placed in the centre of
the compost. The function of
the root zone is not
completely revised at the
moment of writing this
document. However,
according to research from SLU, a dry root zone like the one suggested in this solution, has a
higher reduction potential than conventional soil infiltration that has been extensively used for
wastewater treatment.
Pros and cons
After the initial investment no additional costs are involved. The system is self sustaining and
assures a recirculation of nutrients for biomass growth or even crop production. Since all
components in the wastewater are treated on site, there will be no additional cost for sludge
emptying. Even though a high degree of reduction can be expected there are at the time of writing
no specific results given yet. The Bioglobe system would most likely fulfil the reduction levels
set for this area.
Costs
The total cost for all the components needed for a complete system is €4 250.
The package includes
•
•
•
•
•
•
•
•
•
•
1 vacuum toilet
1 vacuum generator with tank
1 compost container with bottom filter and outlet connection
1 compost cover with opening and alu-profiles
1 heat pipe for freezing prevention
1 starting set of compost worms
1 charger for outdoor use
1 meshbag for leca compost and root zone
installation instructions with drawings
all material needed for the root zone included
The cost for one additional vacuum toilet is €480.
Aquatron toilet separator
Function
Aquatron is a biological toilet system that utilizes an ordinary water closet together with a
compost (fig. 11). A separator physically segregates the solid waste in a time-glass-shaped
device. The faeces and toilet paper are deposited in the central part of the separator and are
composted in an underlying container. The liquid fraction is separated and transported to further
treatment such as soil infiltration or a compact filter. It is also possible to install a urineseparating toilet. The urine can, after a period of storage just like the compost, be spread in the
garden or on farmland. By separating the two fractions, a major part of the phosphorous, nitrogen
and organic content is extracted from the water. The system can also include a UV-light unit that
is connected to the liquid fraction after the separator. The UV-unit will sterilise the faecal
bacteria that were released to the water during the flushing. A simple secondary treatment like an
elevated soil infiltration system or a root zone is still needed for the greywater and the
contaminants that were released from faeces to water prior to separation.
34
In a year-round family household of five
members a four-chamber system is
recommended. After about three to four months
the first chamber is full and the device is turned
90 degrees to fill up the next chamber. Manure
worms can be added to the chambers to achieve
a more efficient decomposition of the organic
material. After a one-year cycle, the content of
the first chamber is suitable for using as a soil
amendment for berry bushes or other plants, or
the chambers can be used for another year before
emptying.
Pros and cons
Aquatron uses an ordinary WC hence there is no
need for installing a new toilet. Installing a urine
Fig. 11. The Aquatron toilet separator
separating toilet would however, result in a
with a compost container and UV-unit
lesser need for nutrient reduction in the
(Aquatron, 2007)
following treatment step and a better recycling
potential for the produced wastewater. The
installation is dependent on available space underneath the toilet or a separate area outside the
house.
A treatment step that involves soil infiltration is as earlier mentioned not suitable for most of the
households in Trzcinisko. Therefore, the urine-separating alternative would be more favourable
since only the greywater and the separated liquid-fraction would need to be treated. This could
after coarse particle separation, be done in a root-zone like the one described in the BioGlobe
section.
When using a compost for separation and treatment of solid toilet waste, it is important to
remember that the treatment relies completely on an efficient biological decomposition of the
organic material. Adding strong acidic or alkaline solutions or other chemicals might alter the
biological function and could therefore affect the decomposition process.
Costs
There are several possible combinations of different sizes and functions that can be chosen to
meet the needs of a household. For a household with up to 5 persons an Aquatron module with
four fractions can be recommended. The price for a complete package for a permanent 5 P.E.
household including biochamber, separator and UV-unit is €3 600. A lesser additional cost will
be needed to cover material costs for the root-zone.
35
Dry toilet systems and separate greywater treatment
Function
A few of the households in Trzcinisko today use a dry toilet that is emptied into nearby ground. A
modern, dry sanitation system, can however if handled in a proper way, be a very efficient and
resource-saving system. Modern dry toilets have the advantage of a more user-friendly function
since the toilet waste is automatically source-separated. Through source separation of the solid
and liquid phases most of the unpleasant smell can be neutralised since the main cause for the
smell are the sulphuric-hydrogen components that are built up in mixed toilet waste. Another
option is non-source separated systems that are well ventilated so that excess liquid is evaporated
from the system to neutralise odours.
Fig. 12. Urine-separating, ventilated dry toilet (Separett, 2007)
The collected and decomposed toilet waste might, like the previous alternatives, be used as a soil
amender in the garden or in agriculture.
Reduction and nutrient recycle potential
The urine fraction contains 80% and the faeces fraction some 10% of the total amount of nitrogen
that is found in sewage water. The urine and faeces together contain a total of 75% of the
phosphorous in sewage water, presuming that phosphorous-containing detergents are used
(Naturvårdsverket, 1995). A change for phosphate-free detergents in combination with a dry
toilet will mean that no additional phosphorous removal is necessary to reach the reduction
targets. The total emissions of biologically oxygen-demanding substances (BOD) from the two
toilet fractions represent 30% of the total BOD substances in wastewater. The rest can be
removed through a settling tank followed by a root-zone infiltration or a plant irrigation system.
Since the toilet fractions together contain a major part of the contaminants in household sewage,
only a lesser treatment of the greywater is needed in order to fulfil the reduction requirements.
The greywater treatment needs, however to render possible a sufficient reduction of virus and
bacteria since these contaminants can be rather high also in greywater.
Pros and cons
A dry toilet is an efficient solution to achieve the reduction limits. It will, however demand a
higher level of maintenance than a traditional water closet. Some of the systems need to be
36
emptied manually. Others are more user-friendly since solid particles are automatically collected
and decomposed, finally leaving a soil rich in nutrients and that can be used directly after storage.
Costs
There are several different dry toilet systems available on the market. One of the most well
known is the urine-separating “Separett”, see fig. 12 above. The cost for one unit including all
necessary separating components is €875 (Separett, 2008).
WM-Tron by Wostman Ecology (Wostman, 2008) is a dry system with a fan but without urine
separation for the total price of €850.
Separate toilet fraction collection and treatment
Function
Sealed tanks are used to collect the toilet fractions. Here, an ultra-low flushing or a vacuum toilet
should be used in order to avoid a rapid filling and frequent emptying of the tank. The greywater
is separately transported to a settling tank and a root zone infiltration like the one described under
the BioGlobe alternative. Since the municipality already has a functioning system for cesspool
emptying and collection, a possible option is to treat the toilet fractions together with plant
residues from local agriculture in an anaerobic bioreactor (fig. 13) that converts the source
material into a stabilized soil fertilizer with very low contents of heavy metals as long as a pure
source material is used. In previous trials of this sanitary system the sealed tanks have been
emptied once per year (Malmén, 2005).
Reduction and recycling potential
Provided that the greywater is treated in a proper way and is excluded from phosphate based
detergents, this method provides a very good potential for nutrient reduction and recycling.
Pros and cons
A large amount of households would need to provide the bioreactor with concentrated wastewater
in order to make this solution a feasible investment. At the time of writing, five bioreactors of this
type are in use in Sweden. They have been constructed in municipalities where a considerably
large amount of the population (about 10,000 households) lacks a connection to communal sewer
systems. In addition, it is an advantage if local agriculture can provide the bioreactor with plant
residues. According to studies from one of the wet compost reactors in Norrtälje, Sweden, the
collected toilet fractions need to be complemented with more energy-dense materials like animal
manure or plant residuals (Malmén, 2005). The adding of animal manure to the bioreactor might
stand a good opportunity to reduce nutrient leakage from large animal farms- a measure that is
realized as one of the most cost-efficient in reducing nutrient leakage to the Baltic Sea (NEFCO,
2007). One of the experiences from the facility in Norrtälje is the need to develop wellfunctioning, vacuum-based low-flushing toilets in order to concentrate the toilet waste. A clear
advantage with this system is the comparatively lower emptying frequencies of once per year,
compared to the current emptying frequency of about 10 collections per year in Trzcinisko. The
less frequent emptying would in the long run mean a considerably lower cost for sewage
emptying compared to today.
37
Fig. 13. The wet compost bioreactor in Norrtälje, Sweden
(Malmén, 2005)
Costs
The costs on a household
level would be rather
limited compared to the
other solutions. The new
installations include an
ultra low flushing toilet
that is separately
connected to a sealed tank
of about 5-6 m3. This
involves some major
changes in the household
sewage pipelines. The
greywater needs to be
coarse separated in a
settling tank and could
thereafter be treated in a
root-zone like the one
mentioned in the
BioGlobe section.
Nevertheless, the cost for constructing the five wet composting bioreactors in Sweden and Åland
has been varying according to the dimensions and technologies used. A facility in Åland was
dimensioned for 60 households with an approximate cost of €290 000. The facility was financed
mainly from external inputs.
5.4.2 Alternatives at the end of the pipe
The alternatives given below are chosen to match the special hydrogeological conditions in
Trzcinisko. With a naturally high groundwater level and a dense soil with a strongly limited
infiltration capacity, the commonly used infiltration systems are not taken into consideration in
this study. Instead, sealed systems with a recycle potential are preferred to meet the reduction
requirements. The proposals are supposed to render possible a local usage of the wastewater
either as a soil amender or for production of useful materials like willow wood or reed.
Combined wetlands and root-zones as a sewage treatment method
Function
Several case studies in Sweden show that artificial wetlands can be rather efficient for wastewater
treatment. These studies have been made on facilities that use wetlands as a polishing step after
the initial treatment in a MWWTP but also on facilities that use wetlands as the main water
treatment directly after coarse particle separation.
An important issue when constructing wetlands for sewage treatment is the physical outline of
the system, meaning the design of deep/shallow parts and the relation between length and width.
38
In order to achieve an optimal reduction of nutrients, there should be a deeper basin right after the
inflow. This facilitates the sedimentation of particulate matter since the kinetic energy of the
incoming water is decreased. Moreover, the length to width relation should preferably not fall
below 2:1 (Knight, 1987). The bottom should be of a rather impermeable soil material in order to
prevent infiltration. For maximal absorption of P it is favourable if the bottom substrate contains
a sufficient amount of iron- or manganese hydroxide. Limestone is another, although less
efficient P-binding agent. Nevertheless, the binding and release of P is rather complex and varies
with pH, depth, oxygen concentration, etc., which make P capture a somewhat complicated task
in wetlands (Tonderski et al, 2002).
The wetland is preferably incorporated with suitable plants for a maximal nutrient reduction. This
solution is commonly referred to as a root-zone system. Flood-tolerant plants with a high growth
rate are favourable for nutrient uptake. A species that is frequently used is common weed. This
plant is not only suitable for water treatment - it also has a direct economic value since it can be
used for roof construction or other building material.
An interesting example is the cultivation and harvest of weed that according to the locals recently
was taking place in the neighbouring community of Błotnik where a farmer got a good price for
exporting his weed as a roof cover material to Scandinavia. In order to achieve an optimal
reduction of nutrients, the weed would preferably be harvested in the beginning of the cold
season right before a major part of the nutrients is stored in the roots.
The combined wetland/root zone should be constructed on a natural low-point in the landscape in
order to avoid expensive excavation work and to take use of the natural water treatment capacity
of the actual site. In Trzcinisko, a suitable place for a wetland could be at the east side of the
community in the direct vicinity of the Martwa Wisła. This area has a plain and low position and
is not cut off by river embankments.
If wetland/ root zone filtration would
be chosen as an alternative, it is
important to consider the drainage
situation in order to avoid flooding
of adjacent farming land or an
unintended drainage of the incoming
sewage water.
Fig. 14. Part of the wetland wastewater treatment site
at Igelösa (Region Skåne, 2006).
39
Reduction and nutrient recycling
potential
While the reduction of nitrogen has
been widely varying depending on
the site and season, the reduction of
BOD7 and phosphorous has been
rather similar at the different sites as
well as on a seasonal basis. In this
context it is relevant to distinguish
between area-specific reduction and
relative reduction.
The area-specific reduction is referred to as the reduction that is reached per wetland area unit,
which is usually given in kg of N or P *ha-1*year-1. In a wetland with a high load of nutrients the
area specific reduction can reach above 1000 kg N / (ha*year) and 150 kg P / (ha*year).
The relative reduction (i.e. the total reduction in percentage of incoming pollutants) has been
varying from around 23% up to 70% of N between the studied objects. The initial intention was
to reduce N in these wetlands. Nevertheless, the reduction of BOD to 5 mg/l and P to 0.1 mg/l
was observed as a positive side-effect. Interestingly, these reduction levels have been rather
constant and independent on the concentration in the incoming water. The reason for this is
probably that a full reduction potential has been reached in the studied systems. Several studies
have shown that constructed wetlands are more efficient in N reduction if a vertical instead of a
horizontal water flow is achieved. A constructed wetland with a vertical water flow has a
function similar to that of conventional on-site infiltration treatment where the contaminants are
consumed by bacteria at the surface of sand of an optimal grain size. Nevertheless, the best
reduction is achieved when the vertical flow is combined with a horizontal flow. This
combination together gives an altering aerobic/anaerobic composition that favours the process of
denitrification (Tonderski et al, 2002).
An example of such a system was constructed in the small community of Igelösa north of Lund in
southern Sweden. Prior to the new treatment the wastewater had after coarse particle separation
been transported to a nearby creek (Region Skåne, 2006). The municipality decided that a new
treatment had to be installed in Igelösa. The 26 households in Igelösa jointly set up a union for
carrying out a wetland wastewater treatment. In order to avoid contamination from the
wastewater, the ponds were constructed at a distance of 200 m from Igelösa. Bushes were planted
along the sides to avoid airborne spreading of contaminants. The wetland area was dimensioned
to 0.6 ha and after 5 years of usage the full capacity was far from reached. It showed out that the
constructed wetland (fig. 14) absorbed all of the generated wastewater since no discharge from
the site was noted. The planners had taken advantage of a combination of vertical and horizontal
flow. Deep and shallow parts as well as willow plantations were used in the different treatment
steps. After 5 years of usage, an evaluation showed that the treatment targets had been fulfilled.
Nevertheless, no harvest of the biomass captured nutrients had been done but parts of the system
were used for goldfish aquaculture and willow plantations.
Pros and cons
The suggested solution involves an exchange of the existing poor cesspools for new settling
tanks. The new settling tank can either be installed in each household or alternatively, a larger
central settling tank is placed prior to the wetland area. This choice also demands a different
performance of the connection pipelines where fractionating pumps would need to be installed in
order to transport the coarse particle containing wastewater.
Both cases will reduce the emptying frequency since the current “sealed” tanks would be
exchanged to tanks that simply separate the solid matter on the bottom or surface. A settling tank
constructed for one household is usually emptied on a one time/year basis. The standard volume
for a single family household is 2 m3. If instead, a central settling tank is placed prior to the
wetland the volume should be dimensioned to the amount of households. Here it is possible to
add a chemical flocking agent for precipitating phosphorus already in the settling tank.
Nevertheless, adding a flocking agent will increase the volume of sludge produced in the settling
40
tank. This can be compensated for by investing in a larger settling tank (4 m3) for a 5 P.E.
household or by choosing a more frequent emptying.
Costs
Approximate cost of a 2 m3 settling tank: €500 (Oczyszczalnie przydomowe, 2007).
The total cost of the wetland treatment in Igelösa was €100,000 or €4,000 /household The cost
for only the filtration installation was €25,500. Nevertheless, the final cost could have been
considerably lower if the facility was not overdimensioned. Total costs might vary largely
depending on the distance between the households and the constructed wetland. It might
therefore not be motivated to connect all of the households to this joint treatment facility.
Combined vegetation filters in a microscale
A variant of the combined wetlands and root-zones alternative is provided by the different natural
treatment methods that have been developed by ecologists and environmental engineers in recent
years.
Function
There is no precise description or definition of these systems but what they do have in common is
that they take advantage of the high absorption potential of nutrients or contaminants that a
specific combination of plants, algae or even animals possess. The treatment process is carried
out on a fraction of the land needed to achieve the same treatment results by a conventional soil
infiltration system (Sweden Today, 2008). The treated wastewater is usually recycled into the
system to be used for irrigation of garden or crop plantations.
One example that takes advantage of these functions is the so-called Eco-restorer system in
Findhorn, UK. Here all
treatment steps are captured in
a greenhouse so as to extend
the treatment function of the
plants throughout the cold
season.
Fig. 15. Part of the wastewater treatment system carried out by
Phytotechnology AB (Phytotechnology, 2008)
41
Another promoter of this type
of treatment is
PhytoTechnology Europe AB.
This treatment method (fig.
15) is based on 15 years of
joint research at the
universities of Lund and
Warsaw. No addition of
chemicals is needed and only a
minimum of external energy
input is necessary. Basically,
the wastewater passes through
a number of separation tanks
and are thereafter treated biologically mainly with the use of a specific composition of algae and
plants. According to one of the inventors, the process does not produce any sludge since all of the
components of the wastewater are recycled within the system (Phytotechnology, 2008).
Reduction and recycling potential
The Eco-restorer system presented above has been tested for reduction levels with the following
results (table 5).
Table 5. Reduction levels measured for the Eco-restorer system (Living Technologies Ltd, 2008)
1
BOD before treatment 250 mg/l
after treatment less than 10 mg/l
3
Tot-N before treatment 40 mg/l
after treatment less than 10 mg/l
6
Tot-P before treatment 7 mg/l
after treatment less than 5 mg/l
The reduction levels from table 5 fulfill the set limits for BOD and N but not for P (see table 2 in
section 2.3.2). Therefore, if this system is chosen, an additional reduction of P is necessary prior
to discharge into a natural water body.
Since the PhytoTechnology system has not yet been tested in full-scale, it is impossible to present
results of this treatment. Full-scale tests for wastewater charges of 1-200 m3 per day are to be
carried out at the Swedish agricultural university (SLU) in Alnarp, Sweden in autumn of 2008
(Phytotechnology, 2008).
Pros and cons
The PhytoTechnology is yet to be evaluated but one advantage is that no sewage sludge needs to
be taken out from the system. According to the developers, this system can promote biodiversity
by the usage of several different species for nutrient absorption. It is furthermore said to be
adaptable to several different natural conditions. Another advantage of these combined
vegetation-filtering systems is their multifunctionality. Apart from treating the wastewater they
can also be used for producing e.g. mussels, fish or other aquaculture species.
Costs
The price for the Living Technology system is dependent on the size of the facility. The designer
can give more information about prices.
The PhytoTechnology system is not yet provided on the market. An introduction is expected for
2008/2009. According to the producers, however, the system should be economically feasible
even for users in developing countries.
42
Willow filters for wastewater treatment
Function
Research on willow beds in Denmark, Poland and Sweden has shown that this option is suitable
for wastewater treatment. One of the more promising constructions from the testing seems to be a
bottom-sealed willow bed that since 1997 has been installed for at least 150 households in
Denmark (Brix & Hasling, 2005), see fig. 16 below. The willow plantation is here dimensioned
to take care of all the produced wastewater through transpiration. This means that the area needed
is far larger than for other treatment methods. On the contrary, the willow yield- and the possible
gain from it are larger since the plantation renders possible a more efficient nutrient absorption.
Given that all the wastewater is taken up in the bed, there is no necessity of installing additional
treatment for reaching the set reduction limits.
In Sweden, willow plantations are extensively irrigated with sewage water. Some of the
advantages with wastewater irrigation are the increased reduction of nutrients from the water, the
savings of chemical fertilisers as well as the avoidance of using high quality drinking water for
irrigation purposes. A study of willow plantations irrigated with wastewater and plantations
without any additional fertilisers added showed that the wastewater irrigation resulted in a 100%
increase in growth rate (Andersson & Andersson, 2000). According to the same study, household
sewage water has a very suitable composition of nutrients for irrigation and fertilisation of willow
plantations.
An important characteristic of willow is its long growing season, which renders possible a more
continuous seasonal nutrient absorption. This means that the effect of cold climate on nutrient
uptake will be less significant than if other species are used for water treatment in temperate
areas. It is here recommended to plant a mix of different willow clones so as to extend the
growing season and to increase the resistance of the plantation. A common belief is that plantbased treatment methods are less efficient during the cold season. In fact, studies have shown the
seasonal differences in reduction levels on willow beds to be negligible (Brix & Hasling, 2005).
One explanation for this could be that the sewage water holds a rather constant temperature of 510 degrees which keeps the biological and decomposing activity going even during periods of
colder climate (Hedström et al, 2007).
Willow bed dimensioning
On a yearly basis the transpiration from the willow bed should equal the amount of precipitation
water and wastewater. The local annual precipitation and its deviations need therefore to be
considered while dimensioning the treatment bed (Brix & Hasling, 2005). The bed should be able
to store water during cold seasons when transpiration is low. Instead of planning the bed
according to the amount of users in the household, the dimensioning is made according to the
total water consumption of the household. Lowering the water consumption will improve the
performance of the willow bed and decrease the area needed.
The willow bed should be 8 meters wide and have a depth of 1.5 metres. It should be constructed
with a 45° slopes on the sides. Calculations from willow bed constructions in Denmark show that
in areas with an average annual precipitation of 530-600 mm, an area of 130-150 m2 is needed for
transpiring 100 m3 of wastewater. If the annually produced wastewater is 150 m3 per annum, the
43
bed area should be 1½ times the initial size, or between 195 and 225 m2. With a width of 8 meters
which is necessary for the membrane construction, the bed will have a length of 24 to 28 metres.
The bed is constructed of one single infiltration pipe that is placed in a layer of washed macadam
(16-32 mm). The infiltration pipe (32-63 mm) should have bottom perforations (8-10 mm) at
every 1 metre of distance. The water needs to be transported through the pipe with a pump to
achieve an even distribution of the wastewater. Gravitational flow cannot be used in this system
since the bed will be clogged with water during the winter. If the infiltration pipe is longer than
30 metres, the incoming water should be pumped out from the centre of the bed. The pipes should
be equipped with an opening at the end in order to simplify an inspection or flushing of the
system. At the bottom of the bed an impermeable layer like a geotextile should be placed. A
drainage pipe (90-120 mm) is placed above the sealed bottom and covered with gravel (8-16
mm). The drainage is connected to an inspection well (350 mm). The pipes should be covered
with a permeable geotextile to prevent clogging. The bed is refilled with soil and a layer of sand
to improve the drainage capacity in soils with a low hydrological conductivity. The first year half
of the plants should be cut down to 15 cm of length from end of January until the end of
February. After the first season half of the bed should be harvested every second year (Brix &
Hasling, 2005).
Reduction and recycling
potential
There is no wastewater
discharge in this system
since all the incoming
components are recycled
in the bed (Brix &
Hasling, 2005). The
nutrients are absorbed in
the growing biomass or
turned over by microbes in
the soil and the water is
transpired from the
growing biomass and the
soil to the air.
Fig. 16. A 200 m2 willow bed serving a household in Denmark (Brix &
Hasling, 2005).
Due to the increasing
demand for biomass as an energy substitute for coal, there is a growing market for willow in
Poland. Willow by tradition makes up a culturally important element in the landscape. It is also a
well appreciated species partly due to its suitability as a handicraft product where it is used for
manufacturing wicker furniture or weaving baskets. Another appliance is as a reinforcement plant
at river and lake embankments (Obarska-Pempkowiak & Kołecka, 2007).
44
Pros and cons
Willow is a fast growing plant which is here utilised for a high nutrient absorption and
transpiration. The produced biomass can be used for energy production and it could possibly
replace part of the coal that many rural Polish households consume for heating.
During the winter when transpiration is low, the willow bed is more easily clogged with water,
meaning that there is a higher risk for exposure to sewage contaminated water. A fence around
the plantation might protect from direct contamination. The sealed willow bed should not be
constructed on the lowest lying terrain. This is to avoid rain water discharge to the bed. The bed
should be constructed at a site with maximal sun exposure so as to increase transpiration.
Costs
The approximate investment cost for a willow bed in Denmark is estimated to about €7,500.
However, after a year when the willow is ready to harvest, the biomass production might also
render some economical advantages since it could be used for energy production as a partial
substitute for coal in domestic heating systems. According to a life-cycle study from Lund
Technical University, a one hectare willow plantation can produce a total of 30 MWh of heat per
annum. An average Swedish household uses 15 MWh of energy for heating per annum
(Börjesson, 2006). Depending on the energy consumption and the technical standards for heating
the houses in Trzcinisko, the willow could support a partial amount of the total energy needed.
Nevertheless, if the biomass is intended to be used for a more efficient energy production it is
recommended to connect a larger number of households to a larger willow filter.
45
6. Discussion
The discussion is divided into the following parts: Methodology, Results, and finally, some
General conclusions are given to summarise the main findings of the study.
6.1 Methodology
The methodology chapter involves the description of two different methods for fulfilling the aim
of the study. The main reason for choosing the HS-method as a basis for the sewage system
assessment was that this method is based upon a standard of sewage systems that is commonly
used in Sweden. However, the final classifications of “good”, “middling” or “poor” are not
related to the HELCOM reduction limits that are aimed for in this study. A system that is
classified as “good” according to the HS-method might not fulfil the reduction levels for sensitive
areas according to HELCOM.
The HS-method was developed as a grading system before the new regulations for wastewater
treatment were applied in Sweden. In the new regulations from 2006, a reduction approach is
used instead of the technical approach that was earlier used to define an approved wastewater
treatment. The new regulations practically mean that it is up to each estate-owner to choose
his/her own treatment method as long as it can fulfil the set reduction requirements. This more
flexible approach renders possible a more differentiated wastewater treatment and hence,
increases the need for individual control programmes or certification of approved solutions for
e.g. wastewater treatment plants for single households.
The HS-method might for other reasons not be optimal for assessing the sanitary situation of
Polish rural households due to the substantial differences in wastewater practices that are found
between the countries. Since in Polish rural households the most common system is the use of
cesspools that are emptied on a comparatively frequent basis, a simple “home-designed” method
was used to check if the cesspools were likely to be sealed or not. The calculations for the
classification are partially based on numeric answers given by respondents to a questionnaire, and
partially based on a national average water consumption of 100 litres per person, meaning that
there is an apparent risk of miscalculations. The water consumption rate of households in
Trzcinisko could differ substantially from the national figure. As a result, this method will never
give a precise classification. However, through site visits in Trzcinisko and contacts with the
locals by personal meetings and a general questionnaire, the overall sanitary situation can be said
to correspond rather well with the results of the HM-classification.
The OWP-method has in this study not been used to its full extent. The reason for this is the time
limitations. The missing part from the complete OWP scheme is the Logical Framework
Approach (LFA) which in itself makes up a complete work unit for identifying the needs of a
project. The LFA is commonly used for project planning by SIDA and other institutions.
Nevertheless, for a relatively source and time-limited study like this, there were other more
efficient and easily available approaches for defining the local sanitary problems in Trzcinisko.
46
A questionnaire was chosen to replace the function of a complete LFA. The answering frequency
(76%) rendered from the questionnaire was surprisingly high.
6.2 Results
The study shows that the natural conditions with high groundwater levels and heavy soils in
Trzcinisko are not suitable for a conventional on-site wastewater treatment. A connection to the
MWWTP is not an option for Trzcinisko since local authorities consider the distance to the
communal grid too far. With these facts in mind, an alternative system has to be found for
Trzcinisko.
The results from the questionnaire showed that at least 17 % of the locals are unsatisfied with the
current sanitation system and that several of them are interested in participating in the planning of
a new solution. Some of the answering households stated that they had plans for improving their
sewage handling. Finally, the OWP-method suggests a fifth step in the planning process; The
choice of the most appropriate solution. In this study however, the suggested solutions are not
representing complete solutions but are rather to be seen as possibilities that can be combined in
one way or the other. Suggesting a complete solution for the community of Trzcinisko is an
impossible task since natural, economical and social conditions vary largely even within the
community. Since the households are spread out with up to 1.5 km in distance, each household
should consider a solution that matches its specific needs. The intention for this study however, is
that at least one of the proposed solutions would match any of the households. After all, it is up to
the locals and the local authorities to choose the final solutions.
Considering the economic perspective, the proposed solutions implicate a wide range of costs.
The dry toilet systems are probably the most economical but do however implicate a higher level
of maintenance since the composting container needs to be either emptied or maintained in other
ways. It is important to remember that the prices given in this report are mainly taken from a
Swedish/Scandinavian context and might therefore not fully correspond to the costs for the same
or comparable installations in Poland. Keeping this in mind, the prices given for construction of a
willow bed could be considerably lower in Poland since both materials and practical work can be
carried out for a lower cost than in this case Denmark.
For the families that lack communal water the household is served by a dug well (nr. 5 and 25).
For these households it is of additional importance that the nearby sewage water is handled in a
safe way in order to avoid contamination of the drinking water. Although there is no apparent risk
for diffuse deep groundwater contamination because of the overlying impermeable soil layers, the
deeper drilled wells still need a local protection that prevents top soil waters from entering the
outtake.
47
6.3 General conclusions
The suggested systems are all chosen to fulfil the requirements stated in the Terms of
Requirements. An overview of the proposals shows however that some of the requirements are
supported to a higher degree.
The proposals are made to serve as suggestions on different methods. There is no obstacle
whatsoever for combining two or more of the suggested methods. For some households it might
make economic sense to connect two or more houses to the same treatment facility.
It is possible that other solutions than the suggested are applicable at some of the estates. The
households in Trzcinisko are distributed over a rather large area where conditions may vary
largely. While groundwater levels are rather high at 30 cm below ground in the northern part of
Trzcinisko, there might be a good enough distance to the groundwater for constructing an
infiltration system at the southern-most estates.
For all of the proposed solutions it is advantageous if non-phosphate detergents are used in the
households. However, for the time being, there is no expected national ban on phosphate-based
detergents in Poland. Instead, it is up to every household to choose a phosphate-free detergent
which might seem like a rather complicated task since the supply is very limited and the
difference in prices significant.
Due to the high fluoride concentrations found at many locations within Cedry Wielkie
municipality, it is highly recommended that the local wells in Trzcinisko be monitored for the
same reason. If analyses show that the drinking water in Trzcinisko is not suitable for human
consumption, there is already a communal grid available that could replace the unfit wells. An
overall connection to the communal water grid would also simplify and make the local
wastewater handling safer.
During meetings with the locals, some creative suggestions were expressed. One was the note
that a neighbouring community had built up a reed cultivation from which a farmer had “made a
good deal” by selling weed on export for the use as a roof cover material to Scandinavia. This
initiative could be an interesting experience if the wetland alternative would be chosen as a
solution. As mentioned earlier in this report, a local enterprise, Truck-Trans, holds a certificate
for handling sewage fractions. These locally available resources and knowledge might show
useful in the further development of a more sustainable wastewater handling in Trzcinisko.
The proposed solutions might look rather costly at an initial glance but considering that many of
them entail stopping of the communal sludge collection they could, seen in a long time
perspective, instead become a saving. Another reason that the cost can be motivated is that the
municipality has been given EU-funding for improving on-site sewage treatment which renders
possible a 50% financial support for a new treatment. In addition, finding and taking advantage of
48
locally available knowledge might be a good initiative also for cutting costs. It would moreover
motivate the users to take a more active role in developing a new system which would hopefully
result in the choice and development of a more user-friendly and long-lasting solution.
The study shows that the HELCOM reduction requirements can be reached by using lowintensive technology that is not dependent on a continuous input of chemicals or highly energy
demanding appliances. At least a few of the above-mentioned solutions could probably prove to
be suitable for the community of Trzcinisko. The technologies are available and in use today. A
major task still lies in bringing these solutions into a more general practical use. Evaluations of
alternative sanitary systems in Sweden however, show that these solutions have been proved
successful generally in areas where people had a high motivation for trying out alternatives
(typically ecovillages) or at sites where conventional techniques were not suitable due to natural
conditions such as poor soil infiltration capacity or high groundwater levels.
A potential obstacle for a wider spreading of these technologies is that the reduction levels set out
by HELCOM and signed by the aligned nations, are not implemented in the national legislation
in Poland. Another difficulty with the here proposed solutions is that some of them (the combined
wetland/root-zone solutions) are complicated to measure and analyse in order to clarify if they
are fulfilling the necessary reduction requirements. Hence, there is an outspoken need for further
studies in the efficiency of root-zone based treatment and other alternative wastewater systems
that if proven to be efficient enough could stand a good alternative at sites where a conventional
infiltration facility is not suitable due to soil- and groundwater conditions. A diversified
wastewater practice like in this case, demands a better overview of the performance of different
systems. Some of the systems need further testing and evaluations, especially when it comes to
user-friendliness and the possible potential for improvements.
Finally, the social acceptance is very likely to stand a key issue in implementing one of the above
mentioned proposals. The social aspects are only taken into consideration to a limited extent in
this study. It is however clear that the suitability of these proposals needs to be estimated through
an agreement and open dialogue between the locals, authorities, manufacturers, entrepreneurs and
possibly also the local farmers. Some of the households have already expressed a will to change
their present sewage system. When choosing a solution, it might also be relevant to consider the
future living standards at the site. A changing lifestyle with more people earning their living in
urban areas would mean a lesser amount of people involved in the local agriculture which might
also change people’s motivation to utilise the proposed solutions.
Bearing in mind the considerable monetary resources that are available from EU-funds for
installations like those here mentioned, it seem to be only a matter of spreading the knowledge
and acceptance by raising a dialogue about the possibilities and future potential that lie behind
these systems.
49
7. References
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53
7. Appendices
Appendix A- Questionnaire on the sanitary situation in Trzcinisko
Appendix B- Map of the technical classification of the sewage systems in Trzcinisko
54