BIOLOGICAL PHOSPHORUS REMOVAL PLUS CHEMICAL POLISHING FOR LOW LEVEL COMPLIANCE Nathan Cassity, Donohue Lake Michigan District Regional Operators Meeting May 21, 2015
Presentation Outline Background BPR + Coagulants Janesville Pilot Studies BPR + Supplemental Carbon Take away points Page 2 May 21, 2015
Background
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
Background 25.0 rbcod/p ratio 20.0 15.0 10.0 5.0 0.0 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 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 40 30 20 10 Curve Converted to BOD/P Ratio NSSD Beloit Fort Wayne Janesville 1 Whitewater Janesville 2 0 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 Fraction of BOD that is VFA Fermenter Benefit
Background Surface plot of BioWin modeling results provides performance map Results with no chemical added 60 45 BioWin shows performance is highly dependent on BOD:P 30 BOD:P 3 5 7 9 BOD:TKN Page 6 May 21, 2015 15
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
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
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
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
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 325 337, 1989. Page 11 May 21, 2015
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
Janesville Case Study
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
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
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
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
2013 Pilot Results Effluent total P 1.2 Effluent Total P 1.1 1.0 Phosphorus Concentration (mg/l) 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 08/24/13 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
2013 Pilot Results Effluent P speciation data Effluent Total P Effluent Filtered Total P Effluent Filtered Reactive P 0.12 0.11 0.10 Phosphorus Concentration (mg/l) 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0.00 08/24/13 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
2013 Pilot Results Effluent phosphorus speciation average values Note: Ortho P is part of reactive P Soluble P 0.076 mg/l Total P 0.160 mg/l Prior to Pilot Reactive Soluble P 0.037 mg/l Non-reactive Soluble P 0.039 mg/l Particulate P 0.084 mg/l Soluble P 0.028 mg/l Pilot Results 0.061 mg/l Total P Reactive Soluble P 0.004 mg/l Non-reactive Soluble P 0.024 mg/l Total P 0.061 mg/l Particulate P 0.033 mg/l Page 20 May 21, 2015
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 60 50 40 30 20 10 Janesville 1 In basin ratio was much higher Janesville 2 Janesville Pilot 0 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 Fraction of BOD that is VFA Page 21 May 21, 2015
2014 Pilot Results Effluent total P versus ferric dose Effluent Total P Ferric Dose 0.50 Phosphorus Concentration (mg/l) 0.45 0.40 0.35 0.30 0.25 0.20 0.15 0.10 200 150 100 50 Ferric Dose (gpd) 0.05 0.00 0 05/11/14 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
2014 Pilot Results Effluent phosphorus speciation average values Note: Ortho P is part of reactive P Prior to Pilot 0.124 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 0.089 mg/l Total P 0.124 mg/l Reactive Soluble P 0.075 mg/l Non-reactive Soluble P 0.014 mg/l Particulate P 0.035 mg/l Page 23 May 21, 2015
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 60 50 40 30 20 10 Janesville 1 In basin ratio was much higher Janesville Pilot Janesville 2 0 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 Fraction of BOD that is VFA Page 24 May 21, 2015
BPR + Supplemental Carbon
BPR + Supplemental Carbon Supplemental carbon can be added to increase BOD:P ratio (and BOD:TKN) Results with no chemical added 60 45 BOD:P 30 Results with supplemental carbon 60 45 BOD:P 30 3 5 7 9 BOD:TKN Page 26 May 21, 2015 15 3 5 7 9 BOD:TKN 15
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
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 50 40 30 20 10 0 Overflow Fermenter (VFAs) Benefit to Anaerobic Zones Janesville 1 Influent Janesville 2 Mixed Mixed Aerated Anaer. Anoxic Aerobic Internal Nitrate Recycle 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 RAS Fraction of BOD that is VFA Effluent WAS Page 28 May 21, 2015
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
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
Supplemental Carbon Pilot 3 Janesville Effluent Phosphorus 2.5 Feed pump plugged for 2 days Effluent Phosphorus (mg/l) 2 1.5 1 0.5 0.35 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
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 60 50 40 30 20 10 Fermenter Benefit Janesville 1 Janesville 2 0 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 Fraction of BOD that is VFA Page 32 May 21, 2015
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
BIOLOGICAL PHOSPHORUS REMOVAL PLUS CHEMICAL POLISHING FOR LOW LEVEL COMPLIANCE Nathan Cassity, Donohue Lake Michigan District Regional Operators Meeting May 21, 2015