BIOLOGICAL PHOSPHORUS REMOVAL PLUS CHEMICAL POLISHING FOR LOW LEVEL COMPLIANCE

Transcription

1 BIOLOGICAL PHOSPHORUS REMOVAL PLUS CHEMICAL POLISHING FOR LOW LEVEL COMPLIANCE Nathan Cassity, Donohue Lake Michigan District Regional Operators Meeting May 21, 2015

2 Presentation Outline Background BPR + Coagulants Janesville Pilot Studies BPR + Supplemental Carbon Take away points Page 2 May 21, 2015

3 Background

4 Background Focus of discussion: BOD:P ratio Importance to BPR Chemical dosing ratio Interactions / interrelationships when chemicals are added to a BPR process CEPT Mixed Liquor Dose Primary Clarifiers Aeration Secondary Clarifiers Page 4 May 21, 2015

5 Background 25.0 rbcod/p ratio Fraction of rbcod that is VFA Page 5 May 21, 2015 Curve used in BNR models EBPR Curve (Barnard et al, WEFTEC 2005) BOD:P provides simple BPR performance gauge BOD/P ratio 60 50Eau Claire Curve Converted to BOD/P Ratio NSSD Beloit Fort Wayne Janesville 1 Whitewater Janesville Fraction of BOD that is VFA Fermenter Benefit

6 Background Surface plot of BioWin modeling results provides performance map Results with no chemical added BioWin shows performance is highly dependent on BOD:P 30 BOD:P BOD:TKN Page 6 May 21,

7 Background Chemical addition for polishing BPR + chemical working together How does this affect BOD:P ratio? Focus on two areas of chemical interaction Mixed Liquor Dose Primary Clarifiers Mixing Aeration Secondary Clarifiers Page 7 May 21, 2015

8 Background Dose point interaction Chemical floc grows and adsorbs reactive phosphorus Mixed Liquor Dose Primary Clarifiers Mixing Aeration Secondary Clarifiers Page 8 May 21, 2015

9 Background In basin interaction Chemical floc continues to adsorb reactive phosphorus Mixed Liquor Dose Primary Clarifiers Mixing Aeration Secondary Clarifiers Mass of chemical floc depends on operating SRT Page 9 May 21, 2015

10 Background BPR interaction Ortho P Chemical lowers P and BOD: P ratio increases P still present for PAO uptake Basin position Mixed Liquor Dose Primary Clarifiers Mixing Aeration Secondary Clarifiers PAOs continue to have an advantage BPR stays healthy Page 10 May 21, 2015

11 Background Chemical addition for polishing Chemical interaction Low level treatment requires high dosing ratios Precipitation of Ferric Phosphate in Activated Sludge: A Chemical Model and Its Verification, Luedecke et al, Water Science and Technology, Vol. 21, pp , Page 11 May 21, 2015

12 Background Chemical interaction Ortho P Chemical dosing occurs at low P providing high dosing ratio Basin position Mixed Liquor Dose Primary Clarifiers Mixing Aeration Secondary Clarifiers Chemical dose point provides best opportunity for low level treatment Page 12 May 21, 2015

13 Janesville Case Study

14 Janesville Background Current flow of 14 mgd A 2 O process configuration Effluent P goal between 0.3 mg/l and 0.5 mg/l Influent Mixed Mixed Aerated Anaer. Anoxic Aerobic Effluent Internal Nitrate Recycle RAS WAS Page 14 May 21, 2015

15 Janesville Background TMDL Implementation for Rock River Janesville has new TMDL permit Monthly mass allocations necessitate effluent P concentrations at or below 0.1 mg/l Compliance schedule of 9 years Page 15 May 21, 2015

16 Ferric Dosing Pilot First pilot testing period September 3 to October 5, 2013 (5 weeks) Low flow period 35 mg/l ferric dose (300 gpd ferric, Q = 12 MGD) This dose is likely too high to be considered polishing Fe : P molar dosage of 7:1 Influent Mixed Mixed Aerated Anaer. Anoxic Aerobic Ferric Chloride Dose Effluent Internal Nitrate Recycle RAS WAS Page 16 May 21, 2015

17 Ferric Dosing Pilot Second pilot testing period June 2 to August 10, 2014 (10 weeks) High flow period Initial ferric dose of 19 mg/l (200 gpd ferric, Q = 15 MGD) Ended at 11.5 mg/l (130 gpd, Q = 16 MGD) Influent This would be considered a polishing dose Mixed Mixed Aerated Anaer. Anoxic Aerobic Fe : P molar dosage of 3:1 Ferric Chloride Dose Effluent Internal Nitrate Recycle Page 17 May 21, 2015 RAS WAS

18 2013 Pilot Results Effluent total P 1.2 Effluent Total P Phosphorus Concentration (mg/l) /24/13 08/31/13 09/07/13 09/14/13 09/21/13 09/28/13 10/05/13 10/12/13 Page 18 May 21, 2015

19 2013 Pilot Results Effluent P speciation data Effluent Total P Effluent Filtered Total P Effluent Filtered Reactive P Phosphorus Concentration (mg/l) /24/13 08/31/13 09/07/13 09/14/13 09/21/13 09/28/13 10/05/13 10/12/13 Page 19 May 21, 2015

20 2013 Pilot Results Effluent phosphorus speciation average values Note: Ortho P is part of reactive P Soluble P mg/l Total P mg/l Prior to Pilot Reactive Soluble P mg/l Non-reactive Soluble P mg/l Particulate P mg/l Soluble P mg/l Pilot Results mg/l Total P Reactive Soluble P mg/l Non-reactive Soluble P mg/l Total P mg/l Particulate P mg/l Page 20 May 21, 2015

21 2013 Pilot Results Observations BOD:P ratio 26.5 Target P was 0.1 mg/l 0.06 mg/l result suggested over dose BPR was not affected Following month P of 0.10 mg/l BOD/P ratio Janesville 1 In basin ratio was much higher Janesville 2 Janesville Pilot Fraction of BOD that is VFA Page 21 May 21, 2015

22 2014 Pilot Results Effluent total P versus ferric dose Effluent Total P Ferric Dose 0.50 Phosphorus Concentration (mg/l) Ferric Dose (gpd) /11/14 05/21/14 05/31/14 06/10/14 06/20/14 06/30/14 07/10/14 07/20/14 07/30/14 08/09/14 08/19/14 Page 22 May 21, 2015

23 2014 Pilot Results Effluent phosphorus speciation average values Note: Ortho P is part of reactive P Prior to Pilot mg/l Total P Soluble P Reactive 0.97 mg/l During Pilot Soluble P Total P 0.96 mg/l 1.0 mg/l Non-reactive Soluble P 0.01 mg/l Particulate P 0.03 mg/l Soluble P mg/l Total P mg/l Reactive Soluble P mg/l Non-reactive Soluble P mg/l Particulate P mg/l Page 23 May 21, 2015

24 2014 Pilot Results Observations BOD:P ratio 38.7 Target P was 0.1 mg/l 0.12 mg/l result suggested under dose BPR was not affected Following month P of 0.12 mg/l BOD/P ratio Janesville 1 In basin ratio was much higher Janesville Pilot Janesville Fraction of BOD that is VFA Page 24 May 21, 2015

25 BPR + Supplemental Carbon

26 BPR + Supplemental Carbon Supplemental carbon can be added to increase BOD:P ratio (and BOD:TKN) Results with no chemical added BOD:P 30 Results with supplemental carbon BOD:P BOD:TKN Page 26 May 21, BOD:TKN 15

27 BPR + Supplemental Carbon Overflow from fermenters provides additional VFA for BPR The remaining VFA flows into the anoxic zone for biological nitrogen removal Primary sludge Fermenters Overflow (VFAs) to Anaerobic Zones Fermented primary sludge Influent Mixed Mixed Aerated Anaer. Anoxic Aerobic Effluent Internal Nitrate Recycle RAS WAS Page 27 May 21, 2015

28 BPR + Supplemental Carbon Overflow from fermenters provides additional VFA for BPR The remaining VFA flows into the anoxic zone for 60 biological nitrogen removal Primary sludge Fermented primary sludge Fermenters BOD/P ratio Overflow Fermenter (VFAs) Benefit to Anaerobic Zones Janesville 1 Influent Janesville 2 Mixed Mixed Aerated Anaer. Anoxic Aerobic Internal Nitrate Recycle RAS Fraction of BOD that is VFA Effluent WAS Page 28 May 21, 2015

29 Supplemental Carbon Pilot Evaluate feeding supplemental carbon from QLF Specialty Products Liquid molasses blend product 7.3 lbs COD per gallon (875,000 mg/l) Pilot Goal Stabilize BPR performance near 0.10 mg/l effluent total P (no filters and no ferric chloride) Page 29 May 21, 2015

30 Supplemental Carbon Pilot QLF product fed into fermenters Fermenters convert product to VFA s VFA loading in fermenter overflow increased 80 gpd QLF Feed (600 lb/d COD) Primary sludge Fermenters Overflow (VFAs) to Anaerobic Zones Fermented primary sludge Page 30 May 21, 2015

31 Supplemental Carbon Pilot 3 Janesville Effluent Phosphorus 2.5 Feed pump plugged for 2 days Effluent Phosphorus (mg/l) mg/l P Average Started feeding 80 gpd QLF Solution 0.13 mg/l P Average 0 7/12/2012 7/22/2012 8/1/2012 8/11/2012 8/21/2012 8/31/2012 9/10/2012 9/20/2012 9/30/2012 Page 31 May 21, 2015

32 Supplemental Carbon Pilot Observations Target P was 0.1 mg/l Supplemental carbon dose achieved 0.13 mg/l Ortho P was stable at 0.06 mg/l Limit for BPR? Another tool in the tool box BOD/P ratio Fermenter Benefit Janesville 1 Janesville Fraction of BOD that is VFA Page 32 May 21, 2015

33 Take Away Points Foundation of the process is BPR Focus on keeping BPR happy Use of chemicals does not hurt BPR process Combination of BPR + chemicals: Can produce low level performance Can improve stability May be more cost effective than chemical alone Supplemental carbon is another option Improves both P removal and N removal Page 33 May 21, 2015

34 BIOLOGICAL PHOSPHORUS REMOVAL PLUS CHEMICAL POLISHING FOR LOW LEVEL COMPLIANCE Nathan Cassity, Donohue Lake Michigan District Regional Operators Meeting May 21, 2015