Optimization of nutrient removal in the WWTP Zürich-Werhölzli

2000 ◽  
Vol 41 (9) ◽  
pp. 63-71 ◽  
Author(s):  
H. Siegrist ◽  
T. Brack ◽  
G. Koch ◽  
A. Nussbaumer ◽  
W. Gujer
Keyword(s):  
Activated Sludge ◽  
Nutrient Removal ◽  
Substantial Reduction ◽  
Operating Conditions ◽  
Operating Costs ◽  
Anoxic Zone ◽  
Excess Sludge ◽  
Separate Treatment ◽  
Nitrogen Elimination ◽  
P Removal

Optimization of nitrifying activated sludge plants towards nutrient removal (denitrification and enhanced P-removal) will lead to substantial reduction of operating costs and improves effluent and operating conditions. At the WWTP Zürich-Werdhölzli, initially designed for nitrification, an anoxic zone of 28% of total activated sludge volume was installed in the initially fully aerated activated sludge tanks and allowed with optimization of the sludge blanket in the secondary clarifiers a nitrogen elimination of 60–70%. Parallel, different small process alterations at the grit removal tank, the primary clarifiers and return sludge pumps reduced odour problems and oxygen input and improved denitrification. Separate treatment of the digester supernatant, that contains about 20% of the inlet nitrogen load, will increase nitrogen elimination to about 75% and allows partial enhanced biological O-removal in the activated sludge system which will reduce precipitant feed and excess sludge production.

Improvement of nitrogen removal at WWTP Zürich Werdhöelzli after connection of WWTP Zürich-Glatt

2004 ◽  
Vol 50 (7) ◽  
pp. 35-43 ◽  
Author(s):  
H. Siegrist ◽  
L. Rieger ◽  
Ch. Fux ◽  
M. Wehrli
Keyword(s):  
Activated Sludge ◽  
Nitrogen Removal ◽  
Substantial Reduction ◽  
Operating Conditions ◽  
Operating Costs ◽  
Effluent Quality ◽  
In Series ◽  
Nitrogen Elimination ◽  
Anammox Process ◽  
P Removal

Optimisation of nitrifying activated sludge plants towards nutrient removal (denitrification and enhanced P-removal) leads to a substantial reduction of operating costs and improves effluent and operating conditions. At WWTP Zürich-Werdhöelzli, initially designed for nitrification only, an anoxic zone of 28% of total activated sludge volume was installed and allowed 60% nitrogen elimination besides several other optimisations. In 2001 the operation of WWTP Zürich-Glatt was stopped and the wastewater was connected to WWTP Werdhöelzli. To improve nitrogen removal, WWTP Werdhöelzli co-financed two research projects; one for separate digester supernatant treatment with the anammox process operating two SBRs in series and the other applying NH4 sensors for aeration control in order to decrease energy consumption and raise effluent quality. The results of both projects and the consequences for WWTP Werdhöelzli are discussed in this paper.

Expenditure on the operation of municipal wastewater treatment plants for nutrient removal

2000 ◽  
Vol 41 (9) ◽  
pp. 281-289 ◽  
Author(s):  
O. Nowak
Keyword(s):  
Nutrient Removal ◽  
Municipal Wastewater ◽  
Wastewater Treatment Plants ◽  
General Scheme ◽  
Operating Costs ◽  
Municipal Wastewater Treatment ◽  
Wastewater Purification ◽  
Labour Costs ◽  
Municipal Wastewater Treatment Plants ◽  
P Removal

Operating costs of Austrian municipal treatment plants are evaluated for 1989/90 and for 1997, respectively. The results indicate that presently the expenses which can be directly connected to wastewater purification, i.e. energy and chemicals for P removal, comprise only about 20% of the total operating costs. Today, in Austria like in other EU countries, the predominating factor is “labour costs”, even at nutrient removal plants. A general scheme for estimating operating costs is presented that can be applied to WWTPs in other parts of the world. In this scheme the important factors relevant to the operating costs are integrated.

Partial ozonation of activated sludge to reduce excess sludge, improve denitrification and control scumming and bulking

2004 ◽  
Vol 49 (10) ◽  
pp. 41-49 ◽  
Author(s):  
M. Böhler ◽  
H. Siegrist
Keyword(s):  
Activated Sludge ◽  
Cost Evaluation ◽  
Anoxic Zone ◽  
Excess Sludge ◽  
Solid Retention Time ◽  
Operation Stability ◽  
Agricultural Use ◽  
Sludge Ash ◽  
And Control ◽  
Sludge Production

Disposal of sewage sludge is forbidden and agricultural use of stabilized sludge will be banned in 2005 in Switzerland. The sludge has to be dewatered, dried, incinerated and the ashes disposed in landfills. These processes are cost intensive and lead also to the loss of valuable phosphate resources incorporated in the sludge ash. The implementation of processes that could reduce excess sludge production and recycle phosphate is therefore recommended. Partial ozonation of the return sludge of an activated sludge system reduces significantly excess sludge production, improves settling properties of the sludge and reduces bulking and scumming. The solubilized COD will also improve denitrification if the treated sludge is recycled to the anoxic zone. But ozonation will partly inhibit and kill nitrifiers and might therefore lead to a decrease of the effective solid retention time of the nitrifier, which reduces the safety of the nitrification. This paper discusses the effect of ozonation on sludge reduction, the operation stability of nitrification, improvement of denitrification and gives also an energy and cost evaluation.

Difficulties and developments in biological nutrient removal technology and modelling

1999 ◽  
Vol 39 (6) ◽  
pp. 1-11 ◽  
Author(s):  
George A. Ekama ◽  
Mark C. Wentzel
Keyword(s):  
Activated Sludge ◽  
Nutrient Removal ◽  
P Uptake ◽  
Biological Nutrient Removal ◽  
Filamentous Bulking ◽  
Recent Developments ◽  
Removal Technology ◽  
Hydrolysis Of ◽  
Activated Sludge Systems ◽  
P Removal

Filamentous bulking and the long sludge age required for nitrification are two important factors that limit the wastewater treatment capacity of biological nutrient removal (BNR) activated sludge systems. A growing body of observations from full-scale plants indicate support for the hypothesis that a significant stimulus for filamentous bulking in BNR systems in alternating anoxic-aerobic conditions with the presence of oxidized nitrogen at the transition from anoxic to aerobic. In the DEPHANOX system, nitrification takes place externally allowing sludge age and filamentous bulking to be reduced and increases treatment capacity. Anoxic P uptake is exploited in this system but it appears that this form of biological excess P removal (BEPR) is significantly reduced compared with aerobic P uptake in conventional BNR systems. Developments in the understanding of the BEPR processes of (i) phosphate accumulating organism (PAO) denitrification and anoxic P uptake, (ii) fermentation of influent readily biodegradable (RB)COD and (iii) anaerobic hydrolysis of slowly biodegradable (SB)COD are evaluated in relation to the IAWQ Activated Sludge Model (ASM) No.2. Recent developments in BEPR research do not yet allow a significant improvement to be made to ASM No. 2 that will increase its predictive power and reliability and therefore it remains essentially as a framework to guide further research.

Potential of activated sludge ozonation

2007 ◽  
Vol 55 (12) ◽  
pp. 181-187 ◽  
Author(s):  
M. Boehler ◽  
H. Siegrist
Keyword(s):  
Sewage Sludge ◽  
Activated Sludge ◽  
Cost Evaluation ◽  
Anoxic Zone ◽  
Excess Sludge ◽  
Solid Retention Time ◽  
Operating Stability ◽  
Agricultural Use ◽  
Sludge Ash ◽  
Sludge Production

The disposal of sewage sludge and the agricultural use of stabilised sludge are decreasing due to more stringent regulations in Europe. An increasing fraction of sewage sludge must therefore be dewatered, dried, incinerated and the ashes disposed of in landfills. These processes are cost-intensive and also lead to the loss of the valuable phosphate resources incorporated in the sludge ash. The implementation of processes that could reduce excess sludge production and recycle phosphate is therefore recommended. Partial ozonation of the return sludge of an activated sludge system significantly reduces excess sludge production, improves the settling properties of the sludge and reduces bulking and scumming. The solubilised COD will also improve denitrification if the treated sludge is recycled to the anoxic zone. However, ozonation partly kills nitrifiers and could therefore lead to a decrease of the effective solid retention time of the nitrifier, thus reducing the safety of the nitrification. This paper discusses the effect of ozonation on sludge reduction, the operating stability of nitrification, the improvement of denitrification and also presents an energy and cost evaluation.

Nutrient removal process development and full implementation at the 4 million p.e. main treatment plant of Vienna, Austria

2004 ◽  
Vol 50 (7) ◽  
pp. 19-26 ◽  
Author(s):  
H. Kroiss ◽  
F. Klager ◽  
S. Winkler ◽  
G. Wandl ◽  
K. Svardal
Keyword(s):  
Activated Sludge ◽  
Nutrient Removal ◽  
Process Development ◽  
Treatment Plant ◽  
High Rate ◽  
Excess Sludge ◽  
Temperature Variations ◽  
Second Stage ◽  
Eu Directive ◽  
The Cost

The Main Treatment Plant of Vienna is in extension for 4 million p.e. and very stringent nutrient removal requirements. The existing high rate BOD removal activated sludge plant (in operation since 1980) is extended by a second stage activated sludge plant and a newly developed flow scheme for nitrogen removal optimisation adaptable to the temperature variations over the year. For this plant pilot investigations have been performed for the development of a specific mathematical model (ASMV) and a specific aeration control strategy. The civil work of the extension is already finished and the installation of the equipment has started. Operation should start in 2004. The whole project will cost about €264 million of which about one half is for civil work. The effluent standards correspond to the requirements for sensitive areas in EU Directive for Municipal Waste Water. The raw primary and excess sludge are incinerated after thickening and dewatering. This paper tries to condense the already existing literature with the construction progress and the cost situation.

scholarly journals Efficiency studies of modified IFAS-OSA system upgraded by an anoxic sludge holding tank

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mansour Fazelipour ◽  
Afshin Takdastan ◽  
Seyed Mehdi Borghei ◽  
Neda Kiasat ◽  
Marcin Glodniok ◽  
...  
Keyword(s):  
Control System ◽  
Activated Sludge ◽  
Removal Efficiency ◽  
Biomass Yield ◽  
New Technology ◽  
Cod Removal ◽  
Yield Coefficient ◽  
Excess Sludge ◽  
Fixed Film ◽  
P Removal

AbstractAn upgraded integrated fixed-film activated sludge-oxic settling anoxic (IFAS-OSA) system is a new technology for reducing nutrients and excess sludge. The results showed that the average TN removal efficiency of the IFAS-OSA system was gradually increased up to 7.5%, while the PO4–3-P removal efficiency increased up-to 27%, compared with that of the IFAS system. The COD removal efficiency of the IFAS-OSA system was slightly increased up-to 5.4% and TSS removal efficiency increased up to 10.5% compared with the control system. Biomass yield coefficient (Yobs) in the IFAS and IFAS-OSA systems were 0.44 and 0.24 (gr MLSS/ gr COD). Hence, sludge production decreased by 45%. The average SVI was decreased by 48% in IFAS-OSA system compared with IFAS. This study demonstrated the better performance of the IFAS-OSA system compared to that of the IFAS system.

Nutrient Removal in a 2-Stage Biological Sewage Treatment Plant

1992 ◽  
Vol 25 (4-5) ◽  
pp. 135-142
Author(s):  
E. Sickert
Keyword(s):  
Nutrient Removal ◽  
Combined Treatment ◽  
Sewage Treatment ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Distribution Channel ◽  
Operating Conditions ◽  
Phosphorus Concentration ◽  
Legal Regulations ◽  
Excess Sludge

The Dradenau sewage treatment plant consists basically of a large activated sludge plant which supplements the treatment stages of the Köhlbrandhöft plant. Although built to mainly oxidize ammonia and despite unfavourable operating conditions - the different locations of the Köhlbrandhöft and Dradenau plants - considerable amounts of nitrogen have successfully been eliminated. Denitrification takes place in the distribution channel of the Dradenau plant and in one of the biological stages of the Köhlbrandhöft plant. This stage takes over the excess sludge from the Dradenau plant resulting in nitrifying - and denitrifying - part of the nitrogen load already here. There is an average overall reduction of 70 %. Simultaneous precipitation at the Köhlbrandhöft treatment plant reduces the phosphorus concentration in the effluent of the combined treatment plants Köhlbrandhöft/Dradenau to values recently set by legal regulations (1 mgP/l).

High Biological Nutrient Removal from Domestic Wastewater in Combination with Phosphorus Recycling

1991 ◽  
Vol 23 (4-6) ◽  
pp. 651-657 ◽  
Author(s):  
J. H. Rensink ◽  
E. Eggers ◽  
H. J. G. W. Donker
Keyword(s):  
Fluidized Bed ◽  
Nutrient Removal ◽  
Domestic Wastewater ◽  
Fluidized Bed Reactor ◽  
Biological Nutrient Removal ◽  
Anoxic Zone ◽  
Domestic Waste ◽  
Average Value ◽  
Phosphorus Recycling ◽  
P Removal

Pilot plant studies on biological nutrient removal and using settled domestic waste water have been carried out in combination with phosphorus recycling on the basis of crystallisation of calcium phosphate on sand pellets in a fluidized bed-reactor. The bioreactor had been divided into four zones, respectively anaerobic, aerobic, anoxic and aerobic. To eliminate nitrate sludge recirculation for denitrification, a part of the influent was led to the anoxic zone. In the by-pass of the bioreactor a phostripper tank was incorporated followed by a fluidized bed-reactor. The experiments carried out at low F/M ratios and at a constant and variable influent flow resulted in nearly 100% P-removal. P-total effluent was lower than 0.1 mg P/l. The total nitrogen content in the effluent amounted to an average value of approximately 16 mg N/l.

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