MORE EFFICIENT MECHANISMS OF BIOLOGICAL PHOSPHORUS REMOVAL

Transcription

1 NEWEA ANNUAL CONFERENCE & EXHIBITION MORE EFFICIENT MECHANISMS OF BIOLOGICAL PHOSPHORUS REMOVAL JAMES BARNARD, MARK STEICHEN & PATRICK DUNLAP January Boston MA

2 AGENDA History of EBPR Proposed mechanisms Alternative flowsheets Possible limitations of existing practices Problems with modeling alternative flow sheets Proposed remedies

3 2 SOME EARLY OBSERVATIONS Hi-rate no nitrification 30 to 40 h in Stripper Supernatant high in P treated with lime All primary effluent to aeration basin RAS thru deep anaerobic conditions Influent Wastewater Return Biomass Aerated P-enriched Lime Sludge Phostrip Process Levin et al (1975) Lime Settling Stripper Effluent Wasted Biomass 3

4 MIXED LIQUOR FERMENTER (MLF) Fermenter resulted from basin configuration and not deemed important Excellent phosphorus removal resulted Note orthophosphates profile through plant Performance could not be replicated in laboratory Barnard suggested organisms (PAO) should pass through anaerobic phase with low ORP which triggered EBPR Suggested Phoredox process by adding anaerobic zone up front Barnard 100 m 3 /d pilot 1972

5 PHOREDOX (AKA AO) CONCEPT OF PASSING ALL PRIMARY EFFLUENT THROUGH ANAEROBIC ZONE

6 2 FUHS & CHEN (1975) Studied the Pho-strip process Suggested PAO take up P when aerobic, use that energy to take up VFA in anaerobic zone Identified PAO as Acinetobacter Mechanisms further developed by Comeau & Wentzel As adapted by Comeau & Wentzel Problem not always sufficient VFA in primary effluent 6

7 VFA FROM FERMENTERS

8 VIEW OF KELOWNA B.C. Fermenter Anaerobic Zones PST

9 2 FURTHER STUDIES IDENTIFIED CANDIDATUS ACCUMULIBACTER AS THE DOMINANT PAO it was incorrectly considered that PAOs were of the genus Acinetobacter. or Tetrasphaera by Fuhs & Chen and others* More recently, culture-independent methods have shown Accummulibacter phosphatis is a PAO which can be grown in enriched cultures * For the purpose of design it will be considered that anoxic P uptake is not significant * *IWA Biological Wastewater Treatment - Principles,, Modeling and Design Henze et al 9

10 WESTBANK WITH FERMENTER Westside Kelowna BC (Westbank) X TN < 6 mg/l BOD < 5 mg/l TSS < 2 mg/l TP < 0.15 mg/l

11 WESTBANK WWTP Primary Anaerob Anoxic 1 Anoxic 2 Anoxic 3 Aerobic 1 Aerobic 2 Aerobic Phosphorus mg/l Tetrasphaera can denitrify Bioreactor Profile Phosphorus by Zone Primary Anaerob Anoxic 1 Anoxic 2 Anoxic 3 Aerobic 1 Aerobic 2 Aerobic 3 Note P uptake in Anoxic Zone

12 MIX OF ORGANISMS IN WESTSIDE PLANT Dunlap et al 2015 FISH Image from WR WWTP Sludge with EUB mix (all bacteria) Shown in Green, Tet2-174 (Tetrasphaera clade 2B) in Orange, and Tet3-654 (Tetrasphaera clade 3) in Red.

13 0.3 PHOSPHORUS REMOVAL WITH SIDE- STREAM FERMENTATION Iowa Hill CO plant From Chris Maher 9/8/2011 9/9/2011 9/10/ Effluent Ortho P mg/l

14 EXPERIMENT AT DENVER METRO RAS Cavanaugh, L., Carson, K., Lynch, C., Phillips, H., Barnard, J. and McQuarrie, J. (2012) A Small Footprint Approach for Enhanced Biological Phosphorus Removal: Results from a 106 mgd Full-Scale Demonstration. Proceedings of the 85 th Annual Water Environment Federation Technical Exhibition and Conference, New Orleans, LA, October 2012.

15 PHOSPHORUS REMOVAL BY RAS FERMENTATION DENVER METRO NSEC Effluent TP NSEC Effluent TSS 15 mg-p/l mg-tss/l NSEC Effluent PO4-P 10/4/ /6/ /8/ /10/ /12/ /14/ /16/ /18/ /20/ /22/ /24/ /26/ /28/ /30/ /1/ /3/ /5/ /7/ /9/ /11/ /13/ /15/ /17/ /19/ /21/ /23/ /25/ /27/ /29/ /1/ /3/ /5/ Cavanaugh, L., Carson, K., Lynch, C., Phillips, H., Barnard, J. and McQuarrie, J. (2012) A Small Footprint Approach for Enhanced Biological Phosphorus Removal: Results from a 106 mgd Full-Scale Demonstration. Proceedings of the 85 th Annual Water Environment Federation Technical Exhibition and Conference, New Orleans, LA, October 2012.

16 CAROUSEL PLANT HENDERSON NV 60 ML/D UPGRADED TO BNR Switching off a mixer in the anaerobic zone resulted in In-plant Fermentation Ortho-P for May ANA Eft SPS SCC Final Eft 0.4 Phosphorus (mg/l) /3/2010 5/4/2010 5/5/2010 5/6/2010 5/7/2010 5/8/2010 5/9/2010 5/10/2010 5/11/2010 5/12/2010 5/13/2010 5/14/2010 5/15/2010 5/16/2010 5/17/2010 5/18/2010 5/19/2010 5/20/2010 5/21/2010 5/22/2010 5/23/2010 5/24/2010 5/25/2010 5/26/2010 5/27/2010 5/28/2010 5/29/2010 5/1/2010 5/2/2010 5/30/2010

17 POSSIBLE LIMITATIONS OF EXISTING CONFIGURATION Were we perhaps selecting mostly for species of Accumulibacter that needed a supply of acetic & propionic acid They could have prevailed in standard anaerobic zones since conditions were not ideal for fermenting species like Tetrasphaera Tetrasphaera can ferment glucose and amino acids and other higher carbon forms and store phosphorus Nguyen et al They actually produce VFA that allow a population of Accumulibacter to grow alongside them They can denitrify under anoxic conditions Why did we not grow them not deep enough anaerobic conditions 2 17

18 WHY DID WE MISS IT? It appears that we need an ORP of <-300 mv most anaerobic zones struggle to get -150 mv Impossible to achieve with nitrates or DO anywhere Most plants were over-mixed with turbulent surfaces that entrained air which prevented deeper anaerobic conditions Standard mixing energy 0.6 hp/kcf need 0.08 hp/kcf (huge saving in energy) Too much air entrained in primary effluent Too much primary effluent per se which may contain very little VFA thus diluting the content of the anaerobic zone and reducing the anaerobic SRT 18

19 ORP IN ANAEROBIC ZONES Anaerobic Zone Conventional Anaerobic Zone Side-stream Fermenter 0 VFA -100 Accummulibacter Accummulibacter ORP (mv ) -200 Tetrasphaera VFA Glucose

20 2 MODIFIED WESTBANK PROCESS Aim for 1 to 2 day SRT in anaerobic zone (12-18 h with fermentate 20

21 WHEN NO PRIMARIES USE MIXED LIQUOR FERMENTER OLATHE KS, SACRAMENTO CA Flow Split Fermentation Power Outage End of MLF Ortho-Phosphate, mg-p/l COD: TKN 7.2 Nitrates 7.5 Average SVI ~ 90 ml/g Hardly any Acetate addition Present Limit 2.3 mg/l /2/13 1/1/14 1/31/14 3/2/14 4/1/14 5/1/14 5/31/14 6/30/14 7/30/14 Time MLF mixed only once per day or less often Guideline SRT of MLF approximately 2 days And here I would like to thank Kevin Clark from Pinery Water for showing us the way 21

22 Black & Veatch LAY-OUT OF CHANGIPLANT - SINGAPORE Aerobic Aerobic Aerobic Aerobic Aerobic RAS Feed Step-feed nitrification/denitrification Achieve EBPR Denite PAO Presence of Accumulibacter & Tetrasphaera The Occurrence of Enhanced Biological Phosphorus Removal in a 200,000 m3/day Partial Nitration and Anammox Activated Sludge Process at the Changi Water Reclamation Plant, Singapore Cao et al,

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24 TETRASPHAERA IMPACTS MODEL BEHAVIOR Anaerobic Process Aerobic Processes Fermentation With Tetrasphaera OHOs Only Sb Tetrasphaera Ordinary Heterotroph Poly-P Growth COD Acetate COD Typical PAO Poly-P PO 4 PO 4 Tetrasphaera Ordinary Heterotroph Growth PO 4 Poly-P Sb COD O 2 COD Poly-P Growth Typical PAO PO 4

25 DRAWBACKS OF PARAMETER ADJUSTMENT Coarse parameter adjustment can offer insight into current model shortcomings but; the adjustment of many variables likely results in over adjustment & compensation, calibration is only possible if all relevant mechanisms are incorporated, and it will provide little predictive power when extrapolating beyond specific scenario. We are working with Northeastern University towards recommendations for better modeling sidestream EBPR as part WERF study Refer to WWTmod 2016 paper for more information; Rethinking EBPR: What do you do when the model will not fit real-world evidence?

26 2 CONCLUSIONS Shortcomings of design resulted in selection for limited variety of PAO, mainly those that need a supply of SCVFA Deeper anaerobic conditions are needed to cultivate fermenting PAO such as Tetrasphaera These organisms can also take up phosphorus under anoxic conditions Limit HRT in anaerobic zone by reduced primary effluent discharge and/or reduced RAS flow Wastewater characteristics irrelevant Modeling for alternative species of fermenting PAOs 26

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