Biological Phosphorus Removal Technology. Presented by: Eugene Laschinger, P.E.

Transcription

1 Biological Phosphorus Removal Technology Presented by: Eugene Laschinger, P.E.

2 Overview What is phosphorus and why do we care? How can you remove phosphorus? Biological phosphorus removal Biological phosphorus removal facilities Tomah, WI Dane-Iowa, WI Cross Plains, WI Reedsburg, WI Rhinelander, WI

3 Phosphorus

4 Phosphorus Regulation Technology based effluent limits Typical = 1.0 mg/l Alternative phosphorus limits (APL) Biological maximum 2.0 mg/l Economics - variance Water quality based effluent limits Based upon target concentration in receiving water Total Maximum Daily Load (TMDL) Can be as low as mg/l for streams and mg/l for lakes

5 Chemical Phosphorus Removal Coagulant Alum Ferric Chloride Ferric Sulfate Poly aluminum chloride (PAC) Advantages Simple Lower capital cost (sometimes) Disadvantages Sludge production Operational costs Chemical handling Consumes alkalinity

6 Biological Phosphorus Removal (BPR) Create an environment to select for organisms that will store phosphorus Requirements Readily biodegradable BOD in the form of volatile fatty acids Phosphorus Cycling between anaerobic and aerobic environments Advantages Low operational costs Improved treatment performance Disadvantages Capital cost More complicated treatment

7 BPR Microbiology Phosphorus accumulating organisms (PAOs) Store excess phosphorus inside cells Release phosphorus for energy in anaerobic environment Take in phosphorus in aerobic environment Identifying PAOs and biological phosphorus removal Anaerobic batch testing Staining techniques DAPI Florescence In-Situ Hybridization (FISH) DNA sequencing

8 Typical Biological Removal Configuration

9 Influent Considerations BOD and phosphorus required for biological phosphorus removal to work BOD should be in readily biodegradable form Nitrate inhibits biological phosphorus removal High influent ammonia will be converted to nitrate if nitrification occurs Frequency and quantity of inflow and infiltration (I&I)

10 Primary Clarifier Removal of nonbiodegradable or difficult to degrade components Use as ACTIVATED primary for production of VFA s Hold sludge blanket Recirculate sludge - elutriation

11 Activated Primary Clarifier

12 Selector Basins Anaerobic environment VFA s formed through fermentation Organisms take in VFA s and store VFA s as PHB Phosphorus released to give PAO energy

13 Anaerobic Environment VOLATILE FATTY ACIDS (INFLUENT BOD) PHOSPHATE ENERGY PHB POLY-P PHOSPHORUS ACCUMULATING ORGANISM

14 Aeration Basins Stored PHB is consumed (BOD) Influent and released phosphorus is taken up to provide energy for future reactions Micro organisms grow and reproduce Higher phosphorus content in cells (>4% vs. 1% - 2%)

15 Aerobic Environment PHOSPHORUS ACCUMULATING ORGANISMS PHB POLY-P OXYGEN OR NITRATE CO2 OR N2 GAS PHB ENERGY POLY-P GROWTH PHOSPHATE (INFLUENT AND RELEASED)

16 Final Clarifiers, RAS, and WAS Phosphorus laden organisms settle Rapid sludge removal (avoid secondary release) Sludge wasting removes organisms and phosphorus from system

17 Waste Activated Sludge PHOSPHORUS ACCUMULATING ORGANISMS ORGANISMS RECYCLED TO SELECTOR BASIN POLY-P POLY-P SLUDGE WASTING P REMOVED FROM SYSTEM IN WASTE SLUDGE POLY-P

18 Special Considerations for BPR Secondary release selector basins and clarifiers Nitrates RAS Recycle streams especially with anaerobic digestion ORP and DO control

19 Tomah, WI WWTP Design Conditions Design Flow 2.3 MGD Peak Hourly Flow 8.0 MGD BOD 4,500 lbs/day TSS 4,750 lbs/day TKN 540 lbs/day Phosphorus 190 lbs/day Unique features High influent phosphorus load Concentration 10 mg/l to 20 mg/l Difficult chemical treatment

20 Tomah, WI WWTP

21 Tomah Start-Up (February May, 2000) Fermenter (Off Line) Raw Wastewater Pre-Anoxic Basin (Off Line) Anaerobic Basin #1 Anaerobic Basin #2 Oxidation Ditch RAS Flow

22 Influent Phosphorus Concentration, mg/l Effluent Phosphorus Concentration, mg/l Tomah February May 2000 Results 75 Inf P Eff P Date 2/7/00 2/14/ 00 2/21/ 00 2/28/ 00 3/6/00 3/13/ 00 3/20/ 00 3/27/ 00 4/3/00 4/10/ 00 4/17/ 00 4/24/ 00 5/1/00 Date (Note: May 18 Influent P mg/l, Effluent P mg/l) 5/8/00 5/15/ 00 5/22/ 00 5/29/ 00

23 Tomah Start-Up (June July 2000) Fermenter Raw Wastewater Pre-Anoxic Basin (Off Line) Anaerobic Basin #1 Anaerobic Basin #2 Oxidation Ditch RAS Flow

24 Influent Phosphorus Concentration, mg/l Effluent Phosphorus Concentration, mg/l Tomah June July 2000 Results Inf P Eff P Date 6/7/00 6/14/00 6/21/00 6/28/00 7/5/00 7/12/00 7/19/00 7/26/00 Date 0

25 Tomah Start-Up (August Dec. 2000) Fermenter Raw Wastewater Pre-Anoxic Basin (Off Line) Anaerobic Basin #1 Anaerobic Basin #2 Oxidation Ditch RAS Flow

26 Influent Phosphorus Concentration, mg/l Effluent Phosphorus Concentration, mg/l Tomah June July 2000 Results Inf P Eff P Date 8/7/00 8/14/00 8/21/00 8/28/00 9/4/00 9/11/00 9/18/00 9/25/00 10/2/00 10/9/00 10/16/00 10/23/00 Date 10/30/00 11/6/00 11/13/00 11/20/00 11/27/00 12/4/00 12/11/00 12/18/00 12/25/00

27 Effluent Phosphorus Concentration, mg/l Tomah Operation ( ) Effluent Phosphorus Concentration Tomah WWTF 3.0 Current Monthly Permit Limit Date

28 Tomah Plant Operating Results Effluent Results 2012 BOD/SS < 5 mg/l Ammonia < 0.5 mg/l Phosphorus < 0.3 mg/l No chemical usage for P removal No control on recycle streaming

29 Dane-Iowa WWTP Design Flow Peak Hourly BOD TSS TKN Phosphorus MGD MGD 1,369 lbs/day 1,501 lbs/day 230 lbs/day 37 lbs/day

30 Dane-Iowa WWTP

31 Effluent Phosphorus Concentration, mg/l Dane-Iowa Performance Dane-Iowa WWTF Monthly Average Effluent Phosphorus Concentration Current Monthly Permit Limit Date

32 Cross Plains, WI WWTP Design Flow Peak Hourly BOD TSS TKN Phosphorus mgd 2.27 mgd 1,376 lbs/day 1,493 lbs/day 155 lbs/day 44 lbs/day

33 Cross Plains, WI WWTP

34 Effluent Phosphorus Concentration, mg/l Cross Plains Performance Effluent Phosphorus Concentration Current Monthly Permit Limit Date

35 Reedsburg, WI WWTP Design Flow Peak Flow BOD TSS TKN Phosphorus MGD MGD 6,331 lbs/day 5,048 lbs/day 687 lbs/day 205 lbs/day

36 Reedsburg, WI WWTP

37 Effluent Phosphorus Concentration, mg/l Reedsburg Performance Effluent Phosphorus Concentration 4.00 Current Monthly Permit Limit Date

38 Rhinelander, WI WWTP Design Flow Peak Hourly Flow BOD TSS TKN Phosphorus mgd mgd 4,277 lbs/day 4,349 lbs/day 423 lbs/day 138 lbs/day

39 Rhinelander, WI WWTP

40 Effluent Phosphorus Concentration, mg/l Rhinelander Performance Effluent Phosphorus Concentration Date

41 Rhinelander Challenges Anaerobic digester recycle streams Carbon need to feed Bio P and anaerobic digester Batching for digester More complex controls

42 Dodgeville, WI WWTP Design Conditions Design Flow Peak Hourly Flow BOD TSS NH3 Phosphorus Typical Discharge MGD MGD 1,925 lbs/day 1,650 lbs/day 380 lbs/day 50 lbs/day.5 mg/l to.7 mg/l with chemical

43 Dodgeville, WI WWTP

44 Dodgeville, WI WWTP WWTP Operational Modifications Revised Process Flow Influent Flow Diverted to Tank #1 Timers Added to Mixers Operated 20 Minutes/Hour WWTP Improvements Effluent Improvements Effluent P reduced to 0.30 PPM annual average Chemical Addition Reduced Previous Chemical Addition Seasonally Reduced Chemical Consumption Saving >$35,000 per Year

45 Marshfield, WI WWTP Design Conditions Design Flow 7.91 MGD Peak Hourly Flow 28.0 MGD BOD 11,000 lbs/day TSS 11,100 lbs/day TKN 1,550 lbs/day Phosphorus 350 lbs/day Unique features High peak flow Designed for only chemical phosphorus removal

46 Marshfield, WI WWTP

47 Marshfield, WI WWTP Plant Performance Prior to Changes in Operation Generally BOD/SS Very Good Required 200 gpd of Ferric Chloride Effluent Phosphorus.7 mg/l to.9 mg/l WWTP Operational Modifications Operate Two Ditches in Series First Ditch Operated with Low DO/Anoxic

48 Marshfield, WI WWTP WWTP Improvements Effluent Improvements Effluent P reduced from 0.90 mg/l to mg/l Chemical Addition Reduced Chemical Addition Reduced to 25 gpd Projected Annual Savings of $95,000 Sludge Dewatering Reduce Polymer Addition 40% to 50% Potential Future Improvement Update Controls Replace Aerators to Lower Power and Improve Mixing

49 Summary Biological phosphorus removal is a reliable alternative for phosphorus removal down 0.2mg/L to 0.5 mg/l or below Designs must incorporate flexibility to ensure systems can be optimized Treatment arrangements should be suited for the specific WWTP Process control allows ease of operation

50 Questions / Comments