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Breaking Loop of Phosphorus Recycle – Side Stream Phosphorus Removal/Recovery

NC AWWA-WEA 93 rd Annual Conference. Breaking Loop of Phosphorus Recycle – Side Stream Phosphorus Removal/Recovery. Yuan Fang, Ph.D., P.E. Chris Wilson, Ph.D., P.E. Dimitrios Katehis, Ph.D., P.E. November 12 , 2013 | Concord, NC. Outline. Phosphorus Resource

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Breaking Loop of Phosphorus Recycle – Side Stream Phosphorus Removal/Recovery

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  1. NC AWWA-WEA 93rd Annual Conference Breaking Loop of Phosphorus Recycle – Side Stream Phosphorus Removal/Recovery Yuan Fang, Ph.D., P.E. Chris Wilson, Ph.D., P.E. Dimitrios Katehis, Ph.D., P.E. November 12, 2013 | Concord, NC

  2. Outline • Phosphorus Resource • Phosphorus Mass Balance in Conventional WWTP and EBPR Plant • Sidestream Phosphorus Removal and Recovery • Model Assistance in Implementing Sidestream P Removal / Recovery • Summary

  3. Outline • Phosphorus Resource • Phosphorus Mass Balance in Conventional WWTP and EBPR Plant • Sidestream Phosphorus Removal and Recovery • Model Assistance in Implementing Sidestream P Removal / Recovery • Summary

  4. Phosphorus Resource • An essential nutrient for all plants and animals • Non-renewable resource that takes 10-15 million years to cycle naturally (phosphate rock) • No substitute available, cannot be manufactured • P reserves worldwide are 71 billion tons

  5. Phosphorus Reserve According to the Global Phosphorus Research Initiatives, current high-grade reserves will be depleted within 50-100 years.

  6. Outline • Phosphorus Resource • Phosphorus Mass Balance in Conventional WWTP and EBPR Plant • Sidestream Phosphorus Removal and Recovery • Model Assistance in Implementing Sidestream P Removal / Recovery • Summary

  7. Phosphorus Mass Balance in Conventional WWTP Disinfection Plant Effluent Influent Aeration Tank (Conventional) Primary Clarifier Secondary Clarifier 269 lbd 195 lbd 289 lbd (72%) (9.2 mg/l) (6.7 mg/l) WAS RAS Primary Sludge Thickener Secondary Sludge Thickener 89 lbd Anaerobic Sludge Digester 16 lbd (6%, Internal P loading) Dewatering Sludge Disposal 74 lbd (1.8% P/TSS) (28%)

  8. Phosphorus Mass Balance in EBPR Plant Disinfection Plant Effluent Influent Aeration Tank (EBPR) Primary Clarifier Secondary Clarifier 269 lbd 56 lbd 514 lbd (21%) (9.2 mg/l) (1.9 mg/l) WAS (PAO) RAS Primary Sludge Thickener Secondary Sludge Thickener 441 lbd (increase 4x) Anaerobic Sludge Digester 228 lbd (44%, internal P loading) Dewatering Sludge Disposal 213 lbd (4% P/TSS) (79%)

  9. Phosphorus Mass Balance in EBPR Plant Disinfection Plant Effluent Influent Aeration Tank (EBPR) Primary Clarifier Secondary Clarifier WAS (PAO) RAS Primary Sludge Thickener Secondary Sludge Thickener NH4+ , PO43- release, Nuisance Struvite Precipitation Anaerobic Sludge Digester Dewatering Biosolids with higher P% Sludge Disposal

  10. Breaking P-Loop in EBPR Plant Disinfection Plant Effluent Influent Aeration Tank (EBPR) Primary Clarifier Secondary Clarifier WAS (PAO) RAS Primary Sludge Thickener Secondary Sludge Thickener Treated Sidestream with Reduced PO4-P Anaerobic Sludge Digester Sidestream with concentrated NH3-N, PO4-P P Removal / Recovery Dewatering Sludge Disposal

  11. Outline • Phosphorus Reserve • Phosphorus Mass Balance in Conventional WWTP and EBPR Plant • Sidestream Phosphorus Removal and Recovery • Model Assistance in Implementing Sidestream P Removal / Recovery • Summary

  12. Sidestream Phosphorus Removal and Recovery Options Physico-Chemical Treatment • Trivalent Metal Complexion/Precipitation • Al3+, Fe3+ , widely used • Increase biosolids production (hauling cost) • Struvite Recovery • Mg2+ + NH4+ + PO43- + 6H2O  Mg(NH4)PO4·6H2O (MAP) • Produce fertilizer with market value • Reduce N loading from sidestream as well

  13. Outline • Phosphorus Reserve • Phosphorus Mass Balance in Conventional WWTP and EBPR Plant • Sidestream Phosphorus Removal and Recovery • Model Assistance in Implementing Sidestream P Removal / Recovery • Summary

  14. Model Layout for Case Study Facility Centrifuge feed tube - 12 weeks following commissioning. Struvite Crystal Build-up, Centrate Sump Pump Volute and Impeller Sidestream Treatment

  15. Case Study Facility Process Model, TP Balance EBNR Process (Five-Stage Bardenpho) Unit: pounds per day 4,160 3,174 1,110 1,110 (4.4 mg/l) Side Stream 2,232 (115% of influent P) 1,928 1,928 986 2063 986 0 405 1,827 1637 1637 3,699 3,699 3,294 1,637 1,637 TP Balance Total In: 1,928+1,637 = 3,565 lbd Total Out: 1,110+2,453 = 3,563 lbd Side Stream: 1,827+ 405 = 2,232 lbd 189 1,638 1,827 4,091 4,091 2,453 2,453 Centrate Recycle NH4-N: 650 mg/l Ortho-P: 459 mg/l 797

  16. Case Study Facility Process Model, TP Balance EBNR Process Plus Sidestream Ferric Addition Unit: pounds per day TP Balance 255 (1.01 mg/l) Total In: 1928+1637 = 3565 lbd Total Out: 255+3305 = 3560 lbd Side Stream: 365+484 = 849 lbd WRF Influent Side Stream 849 (44%) 1928 365 484 Sludge from Other WRF 1637 377 950 kg Fe/d 3653 Centrate Recycle NH4-N: 708 mg/l Ortho-P: 7.5 mg/l 3305

  17. Case Study Facility Process Model, TP Balance EBNR Process Plus Struvite Recovery_Method 1 Unit: pounds per day TP Balance (lbd) 267 (1.06 mg/l) Total In: 1928+1637 = 3565 lbd Total Out: 267+2078+1216 = 3561 lbd Side Stream: 337 + 150 = 487 lbd 1928 Side Stream 487 (25%) 337 150 1637 1254 3333 Recycle Stream NH4-N: 533 mg/l Ortho-P: 11 mg/l 2078 1254 1216

  18. Case Study Facility Process Model, TP Balance • EBNR Process Plus Struvite Recovery_Method 2 Unit: pounds per day TP Balance 249 (1.0 mg/l) Total In: 1928+1637 = 3565 lbd Total Out: 249+1967+1351 = 3567 lbd Side Stream: 239 lbd WRF Influent 1928 Side Stream 239 (12%) 239 Sludge from Other WRF 341 1637 1152 3118 Centrate Recycle NH4-N: 156 mg/l Ortho-P: 16 mg/l 1967 1351 1493

  19. Comparison_Biosolids

  20. Comparison_Sidestream Nutrient Loads

  21. Payback Period Analysis for Struvite Recovery Note: Using ferric iron addition as the baseline for comparison O&M Cost: O&M labor, power, chemical, lab O&M Saving: Aeration, chemical (ferric), sludge hauling, market value of struvite

  22. Outline • Phosphorus Reserve • Phosphorus Mass Balance in Conventional WWTP and EBPR Plant • Sidestream Phosphorus Removal and Recovery • Model Assistance in Implementing Sidestream P Removal / Recovery • Summary

  23. Summary • Sidestream P removal/recovery is beneficial to EBPR system in terms of • Reduce sidestream P load to the main plant • Improve bio-P stability • Reduce nuisance struvite precipitation • Whole plant model is an effective tool to • Evaluate sidestream treatment performance • Assist in optimizing struvite recovery

  24. Summary • Compare to metal addition, struvite recovery has following advantages: • Reasonable payback period • Reduce aeration need and biosolids hauling cost • Produce struvite that has market value • Reduce P content in biosolids • Support sustainability of P resource

  25. Several proprietary processes exist to manage struvite precipitation Multiform Harvest Cone DHV Crystalactor Ostara Pearl Process Veolia Aeration/CO2 stripping

  26. Struvite Recovery Process Configuration

  27. Thank you for your time! QUESTIONS? Contact Information: • Yuan Fang, Ph.D., P.E. yfang@greeley-hansen.com

  28. Several proprietary processes exist to manage phosphorous precipitation Multiform Harvest Cone DHV Crystalactor Ostara Pearl Process Veolia Aeration/CO2 stripping

  29. Biosolids Phosphorus Management Regulations

  30. Typical Sidestream Characteristics 30

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