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Good at the First Drop: Start-up of the Western Wake Regional WRF Meets Summer Permit Limits 95 TH Annual Conference | November 2015 | Raleigh Convention Center, Raleigh, NC Chris White, PE
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Acknowledgements Town of Cary Damon Forney Greg Johnson Hazen and Sawyer Barry Bickerstaff Katya Bilyk Bob Difiore Ron Taylor David Wankmuller
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Agenda Introduction Background Permit Facilities Process Model Sampling Start-up Results
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Introduction New Influent and Effluent Lines New Plant Summer Limits Meet Permit on Day 1 Use Basin Capacity to Hold Flow
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Background Western Wake Partners Town of Apex Town of Cary Town of Morrisville Interbasin Transfer Certificate Discharge to the Cape Fear River Basin Western Wake Regional Water Reclamation Facility – WWRWRF Wastewater Management Facilities – WWRWMF
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Interbasin Transfer Cape Fear River Basin Neuse River Basin
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Timeline 1992 Interbasin Transfer Certificate 2001 Interbasin Transfer Certificate With Conditions 2002 Planning Studies Began 2011 Construction Began 2014 Placed in Service
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NPDES Permit Monthly Average Weekly Average BOD 5, mg/L April – October5.07.5 November – March10.015.0 TSS, mg/L30.045.0 Ammonia, mg/L April – October1.03.0 November – March2.06.0 TN (April – October), mg/L5.0 TP (April – October), mg/L0.75 TN Load (April – October)112,400 lbs/season TP Load (April – October)16,100 lbs/season
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NPDES Permit Fecal Coliform, N/100 mL200 Monthly400 Weekly DO, mg/L6.0+ Daily Average pH6.0 – 9.0 Daily TKN, NO 3 -N + NO 2 -NWeekly Total Copper, Total Zinc, Conductivity,Monthly Chloride, Total CyanideMonthly Chronic Toxicity, Total MercuryQuarterly Pollutant ScanAnnual
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Western Wake Regional Wastewater Management Facilities Influent Conveyance 2 major pump stations ~9 miles pipelines Wastewater Treatment New 18 MGD WRF Effluent Conveyance Pump station ~11 miles pipeline Outfall at Cape Fear River
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Pump Stations / Conveyance West Cary Pump Station – Upgraded Beaver Creek Pump Station – New West Cary Force Main West Reedy Branch Gravity Sewer Beaver Creek Gravity Sewer Beaver Creek Force Main
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Western Wake Regional WRF Headworks Switchyard Effluent Pump Station Solids Handling Biological Reactor Basins Odor Control Administration & Maintenance Generators Clarifiers Filters Disinfection Post Aeration Bulk Chemicals
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Basin Configuration Four Biological Reactor Basins (BRBs) Nine Cells Mixers: Cells 1 – 4 Jet Aeration and Mixing: Cells 5 – 9
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Splitter Box Sluice gates direct PTE to each of the four BRBs Scum pumping station collects and sends scum to the scum digester
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Basin Flow Preliminary Treatment Effluent – Cells 1, 2, or 3 Return Activated Sludge – Cells 1, 2, or 3
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Recycles Fermentation Recycle – Cell 2 to Cell 1 Anoxic Recycle (ARCY) – Cell 4 to Cell 2 Nitrified Recycle (NRCY) – Cell 7 to Cell 3 BRB Drain Pump Station – return to Splitter Box Fermentation Recycle BRB Drain Pump Station Anoxic Recycle Nitrified Recycle
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Aeration Four High Speed Blowers Jet Aeration and Mixing – Cells 5 – 9 Coarse Bubble Diffusers – Effluent Channel Blower Room
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Process Configuration PTE RAS Fermentation Recycle ARCY NRCY Fermenter Anaerobic Anoxic Aerobic Post Anoxic
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Chemical Feed Points Supplemental Carbon Cells 3 and 8 (Anoxic zones – denitrification) Metal Salt Cell 9 and Effluent Channel Polymer Effluent Channel
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Clarifiers Clarifier Influent Channel Clarifier Effluent Channel
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Clarifiers Scum Pump Station RAS Pump Station WAS Pump Station
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Process Model
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1 Basin 0.75 MGD, Adequate nitrification / denitrification capacity Second basin before 2 nd flow step-up Seeding ~600 mg/L target Model degradation effects Supplemental carbon Model predicted glycerin addition helps heterotrophs, but may negatively impact AOBs and NOBs Flow step-up 0.75 MGD to 2.66 MGD would require second seeding Split step-up into two events to give biomass time to grow
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Process Model Chemicals Caustic Glycerin Ferric Polymer Solids 52 days to wasting (2500 mg/L MLSS) Intermittent wasting would not improve biomass growth
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Batch Testing Concurrent with seeding – July 21 – 25 Evaluate nitrification Expected performance Quantify degradation Confirm seeding needs
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Batch Testing
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Seeding 5 days – July 21 – 25 Flow Starts – July 28 Additional Seeding – July 30 Potential Seeding – Aug 1 mg NH3-N / g VSS / hr July 229.4 July 25, pH 7.86.8 July 25, pH 7.03.2 July 290.5 July 29, repeat2.4 July 317.5
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Seeding
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Influent Flow
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Recirculation Pumps Fermentation ARCY NRCY RAS All off at first except RAS Maximize nitrification time
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DO Control
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Caustic Feed Alkalinity concerns Feed issues (Manual drip) Recycles to distribute
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Caustic Feed
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Total Nitrogen Limit Supplemental Carbon Start August 8 Feed points Both anoxic zones Cell 8 aeration stopped Reaeration Zone (Cell 9) – Anoxic Rely on Effluent Channel single drops
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Total Nitrogen Limit
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Nutrient Profiles Abbreviated profiles during Batch Tests Aug 2 Aug 7 Aug 9 Aug 10 Secondary Effluent Began Aug 12
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Nutrient Profiles – Ammonia
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Nutrient Profiles – Nitrate
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Results
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Timeline July 21 – 25Seeding July 28Flow Starts July 30Additional Seeding August 8 Supplemental Carbon Feed Starts August 12Secondary Effluent Starts
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Results InfluentEffluent NO x <0.05 mg/L1.19 mg/L TKN30.4 mg/L0.831 mg/L TN30.4 mg/L2.02 mg/L TP4.17 mg/L<0.10 mg/L
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Questions Chris White cwhite@hazenandsawyer.com
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