Case study on modernising Soviet time WWTP for Nutrient Removal

Transcription

1 Case study on modernising Soviet time WWTP for Nutrient Removal PRESTO Training Workshop St. Petersburg, Dr. Peter Hartwig, aqua consult / Germany Dr. Taavo Tenno, OÜ aqua consult baltic, Tartu/ Estonia

2 Independent Consulting and Planning Engineers for Water, Wastewater, Solid Waste and Environmental Protection Technology Worldwide Experience from the planning and realization of more than 1,000 projects in the field of environmental protection in the last 30 years

3 Independent Consulting and Planning Engineers for Water, Wastewater, Solid Waste and Environmental Protection Technology Worldwide OÜ aqua consult baltic Since 1996 office in Estonia with today 15 wastewater engineers and russian language ability in Tartu

4 Fields of specialization Consulting for Environmental Protection Industrial wastewater Municipal wastewater Waste management Sewerage Systems Water supply Biogas-Projects Cost and fee calculation Plant operation Project management Turn-Key-Projects

5 Examples for the rehabilitation of exisiting WWTP plants for N- and P-removal Basics Optimization of individual components Change of process technology of the biological stage Change of the function of existing components Adding of components Small size plants rehabilitation

6 Basics At first an evaluation of the current operation conditions and results is required Evaluation of the current quality of the civil works and the installations and definition of remaining expected lifetimes for the components Working out rehabilitation procedures with different degree of usage of the existing plant

7 Optimization of exisiting components Final clarifier inlet structure Process control

8 Final clarifiers, Kläranlage used aqua Rheda for consult - the Übersichtsbild research project

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11 X TS,AN [g/l] aqua consult 0,025 Becken 1 Becken 2 0,020 DWA-A 131 design peak flow 0,015 0,010 0,005 0,

12 Optimization of the inlet structure

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14 Increasing of the capacity of existing final clarifiers

15 Process control Installation of process control technolgogy Flow mesurement (inflow, return sludge) Oxygen meters Online measurement devices for nitrogen (NH 4 -N, NO 3 -N) Developing of a strategy to use the existing components in the best way Individual solution required

16 Change of process technology of the biological stage Example with the change of the operation mode

17 Bild der Belebungsanlage aqua consult Munster DN N DN N Operation problems: - No sufficient denitrification because of too short contact time in the denitrification zone (nitrification is ok) - Filamentous sludge with bad settling characteristic (high dilution, around 80 internal recycle times during average retention time )

18 Growth-velocity [1/d] Monod-Relation Example for bacterias which grow in biomass-flocs Example for filamentous bacterias, active under lower concentrations Substrate-concentration

19 Denitrification Bild der Belebungsanlage aqua consult Nitrification Munster Clarifier Solution: Change from simultaneous to alternating Denitrification

20 Nitrification Bild der Belebungsanlage aqua consult Denitrification Munster Clarifier Change from simultaneous to alternating Denitrifikation

21 Alternating denitrification I Denitrification II Nitrification Zulauf Inflow I II I Denitrifikation II Nitrifikation I Nitrifikation II Denitrifikation Nachklärung Final clarifier Ablauf Effluent I Nitrification II Denitrification Rücklaufschlamm Recycle sludge

22 Change of the function of existing components Example Polva/ Estonia Usage of the boiological stage for mechanical treatment/ storage/ Biology Example Tartu/ Estonia Usage of the primary sedimentation tanks for a biological stage

23 Põlva/ Estonia before renewing

24 WWTP Põlva/ Estonia after renewing Building for mechanical treatment, electric supply, blower station

25 Mechanical treatment aqua consult (screen, sand removal) Storage II Storage I

26 South estonian training center for WWTP operators

27 WWTP Tartu/ Estonia Problems: - too big sedimentation tanks - not enough space for nitrogen removal in the bioloigcal stage

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29 SBR-Technology

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31 Adding of components Adding of a primary sedimentation Adding of a cloth filtration Selector for a better sludge settling characteristic Degasing to better the sludge settling characteristic

32 Adding of a primary sedimentation Reduction of the load to the bioloigical stage (30 50 %) If anaerobic sludge tretament is used: Biogas production Reduction of the sludge mass to be disposed Example: Ljubljana/ Slovenia enlargement from 430,000 PE to 550,000 PE without enlargement of the biological stage

33 Filtration after the final clarifier Allows a higher MLSS concentration in the biological stage Possible alternative for an enlargement of the biologcal capacity of a plant Example: cloth filtration behind final clarifiers in Oldenburg/ Germany and Ljubljana (planning stage)

34 Disc filter with cloth material for concrete tanks

35 oil- separator Cloth filtration with a specific pile fabrics suction beam crude sewage pile coarse-porous carrier fabric filtrate

36 Cloth Filtration aqua consult

37 Clothfiltration Oldenburg/ Germany Design SS in the effluent of the final clarifier: 50 mg SS/l!

38 Adding of a selector to better the sludge settling

39 Selector gives an advantage for the floc forming bacterias

40 Adding of a degasing system for a better settling (WWTP Tartu)

41 Without Degasing With Degasing

42 Biogradex Degasing system

43 Application of nutrient removal for 1.5 million PE and 730 WWTP 1994 no wastewater treatment plants with nutrient removal in Estonia 2001 N- and P- removal on the basis of EU environmental standards stepwise legalisation of HELCOM agreement P 0,5 mg/l N effluent limitation starting from 300 PE 2012 Estimated WWTP-s with nutrient removal

44 There are about 730 WWPS in Estonia 6 WWTP > pe: Tallinn; Tartu, Narva, Kohtla-Järve, Pärnu, Rakvere 12 WWTP pe : Võru, Valga, Põlva, Viljandi, Jõgeva, Põltsamaa, Paide, Rapla, Haapsalu, Kuressaare, Paldiski, Tapa; 31 WWTP pe; 680 WWTP <2000 pe; ca 70% pe;

45 How nutrient removal was initiated 6 WWTP > pe: Tallinn - stepwise rehabilitation and enlargement Tartu - stepwise rehabilitation and enlargement Narva - new plant Kohtla Järve - new plant Pärnu - rehabilitation Rakvere - stepwise rehabilitation and enlargement 12 WWTP pe : Võru - N Valga - R Põlva - R Viljandi - N Põltsamaa - R Jõgeva - N Paide - N Haapsalu - R Rapla - R Kuressaare - N/R Sillamäe - N Tapa - N

46 Põlva/ Estonia before renewing

47 WWTP Põlva/ Estonia after renewing Building for mechanical treatment, electric supply, blower station

48 Stepwise reconstruction of Põlva WWTP Biological N-P removal Extension of aeration Sludge treatment Drum composting Extension biological stage

49 Võru wastewater treatment plant pe Yellow FIDIC tender Construction company can influence the process and technology Decision needed Reconstruct old plant / build new

50 Võru wastewater treatment plant Reconstruct the plant based on the old basins Potentially cheaper NEW Old concrete basins need to be covered to meet 50y concrete life cycle Final clarifiers difficult to reconstruct (8 pc, difficult hydraulics, wrong inclinations) Effluent guarantee during the construction time

51 Võru wastewater treatment plant NEW WWTP was built SBR technology High hydraulic variations Flexible operation Sludge composting plant

52 Arke wastewater treatment plant Slaughterhouse (2000 -> 5000 pe) 2005 no active biological treatment (bioponds) Old concrete WWTP structures Shallow tanks Small inclinations for final clarifier DECISON NEW / reconstruct old basins RECONSTRUCT SBR technology

53 Thank you for your kind attention!