Process Control in the Ozonation Process to Eliminate Micro

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Process Control in the Ozonation Process to Eliminate
Micro-Pollutants in Waste Water
Dr. Heidrun Tippe, Endress+Hauser Messtechnik, DE
Max Schachtler, Nathalie Hubaux, WWTP Neugut, CH
Slide 1
05/06/2016
Tippe - Schachtler - Hubaux
Process Control in the Ozonation Process to Eliminate Micro-Pollutants in Waste Water
Motivation
• Elimination of Micro-Pollutants (MP) from wastewater is advancing
from theory to becoming implemented as a new process step in
plants
• Ozonation and Powdered Activated Carbon (PAC) seems to be the
most important technologies for the 4th treatment step
• In Switzerland, 100 selected wastewater treatment plants (WWTP)
have to be upgraded to guarantee an average elimination
performance of about 80% minimum by legislation.
• the SAC (Spectral Absorption Coefficient) is already recognized as a
very suitable parameter to implement process control
• The target is to manage the new processes at the WWTP Neugut
more reliable and efficient
Slide 2
05/06/2016
Tippe - Schachtler - Hubaux
Process Control in the Ozonation Process to Eliminate Micro-Pollutants in Waste Water
The Spectral Absorption Coefficient SAC
• self-absorption of the substances in the water
on a defined measuring wavelength (254
nm), offers a sophisticated possibility in many
applications to get information about the
current water load.
• The measurement principle based on the
absorption of ultraviolet light(254 nm) by
present substances in proportion to their
concentration.
• reference wavelength, e.g. 550nm to limit
interferences from turbidity, contamination or
other organic hydrocarbons
• The substances concentration is determined with
the aid of a calibration curve saved in the system
as SAC (1/m) or directly as ‘TOC’, ‘COD’, ‘BOD’
Slide 3
05/06/2016
Tippe - Schachtler - Hubaux
Process Control in the Ozonation Process to Eliminate Micro-Pollutants in Waste Water
Starting point: Stable and reliable Process Values
• Engineering and a careful
selected installation have the
same impact on data reliability
and availability as maintenance
during operation
• Ozonation process makes a
measurement at the lower end of
the measuring range necessary
• Bypass with sufficient flow
conditions to and from the sensors
• Continuous cleaning system for the
SAC sensors
• Optional: redundancy
Slide 4
05/06/2016
Tippe - Schachtler - Hubaux
Process Control in the Ozonation Process to Eliminate Micro-Pollutants in Waste Water
Intelligent sensors – today and tomorrow
Self-diagnosis functions of modern sensor systems open new
opportunities to support increasing quality and maintenance
management demands
• Today: Device diagnostic information, i.e. operating hours counter of critical
compounds or internal storage of calibration intervals
• Tomorrow: Additional monitoring interfaces for trend identification and
system condition information based on web-server technologies over Ethernet
Slide 5
Diagnostics
Verification
Monitoring
Safe processes
Reduced verification effort
Optimization of process and
maintenance strategy
05/06/2016
Tippe - Schachtler - Hubaux
Process Control in the Ozonation Process to Eliminate Micro-Pollutants in Waste Water
WWTP Neugut in CH
• The first Swiss WWTP with large-scale
Ozonation
• Treatment capacity: 150.000 PE
• Current load: 100.000 PE
• 50% municipal – 50% industrial (food industry)
new act in CH
(01.01.2016):
• >80% MP removal
• 12 lead substances
• 48h-samples 12x / year
primary
clarifier
secondary
clarifier
since 2014
ozone reactor
sandfiltration
biology
4th treatment step
digestion
Slide 6
05/06/2016
digestion
Tippe - Schachtler - Hubaux
Process Control in the Ozonation Process to Eliminate Micro-Pollutants in Waste Water
The Ozonation scheme
Inflow ozonation:
Ozone reactor
• Full-flow
• Qdim, max = 660 l/s ; QDW, av = 200 l/s
• Vtot = 530m3 ; HRTmin = 13min
• O3 dosage in chamber 1 and 3
Ozone production
• O3 produced from liquid O2
• 2 O3 generators (capacity: 2 x 5.5 kgO3/h)
Slide 7
05/06/2016
Tippe - Schachtler - Hubaux
Process Control in the Ozonation Process to Eliminate Micro-Pollutants in Waste Water
The Control Strategy – principle BEAR
Is it possible to
target kgO3/h
= gO3/m3 * Q
•
achieve a constant 82±2% EMP?
•
measure the EMP online?
with a simple and reliable
Q
technology?
target
gO3/m3
BEAR
SACOUT
SACIN
ΔSAC
With BEAR: 0.33 - 0.5 gO3/gDOC
Slide 8
05/06/2016
BEAR control strategy:
Best Elimination, Analysis and
monitoRing
Advantages BEAR:
Tippe - Schachtler - Hubaux
•
continuous and stable EMP
•
needs-oriented O3production
•
O3 consumption reduced
•
O3 excess avoided
•
easy to customize
•
only SACIN & SACOUT
Process Control in the Ozonation Process to Eliminate Micro-Pollutants in Waste Water
The BEAR control strategy - Results
ΔSAC
O3 concentration
(gO3/m3)
ΔSAC = 42 ± 2 %  EMP = 82 ± 2 %
ΔSAC
needs-oriented O3
concentration
days
Slide 9
05/06/2016
Tippe - Schachtler - Hubaux
Process Control in the Ozonation Process to Eliminate Micro-Pollutants in Waste Water
The BEAR control strategy - Results
• …
ΔSAC
= indicator EMP
(12 lead substances)
EMP = 82 ± 2 %
= control parameter
= monitoring parameter
ΔSAC = 42 ± 2 %
ΔSAC depends on:
• type of sensor
• installation of sensor
ΔSAC
 has to be defined for each
WWTP
Slide 10
05/06/2016
Tippe - Schachtler - Hubaux
Process Control in the Ozonation Process to Eliminate Micro-Pollutants in Waste Water
Conclusion
SAC technology is useful for the controlling and monitoring of the ozonation
 Installation and maintenance of SAC sensor are crucial
Other control strategies are possible but lead to:
 EMP not stable
 Process not optimised
Neugut has shown that :
 ∆SAC = indicator for the EMP (Ø 12 lead substances) For the online monitoring of
the EMP, ∆SAC required.
 with BEAR: EMP = 82±2%
 implementation of BEAR
requires nothing more
 easy online monitoring of EMP with ∆SAC
Visit our homepage : www.neugut.ch
Or contact us: [email protected]
Slide 11
05/06/2016
Tippe - Schachtler - Hubaux