87th OWEA Annual Conference, Mason, OH, Wednesday, June 19, 2013 Energy Savings with High Rate Aeration Mark R. Greene, Ph.D. Senior Technical Director O’Brien & Gere © 2013 O’Brien & Gere 87th OWEA Annual Conference Today’s Presentation Objective Frank E. Van Lare WWTP, Monroe County, NY Oxygen transfer efficiency Aeration upgrade Side-by-side testing Performance and measured savings What these results mean 2 © 2013 O’Brien & Gere Objective Maximizing Energy Saving with Aeration Upgrade  Convert surface mechanical (60, 2-speed units) to fine bubble aeration  Predicted saving of 7.4 GWh/yr and $550,000/yr  Enhance operability and process flexibility  Minimal noise emission  Maintain compliant plant operations during construction  Phased approach with consideration of primary tank improvements 3 © 2013 O’Brien & Gere Frank E. Van Lare WWTP, Monroe County, NY 135/200/630 MGD Treatment Plant  Preliminary Treatment (630 MGD)  Screen and grit removal  Primary Treatment (200 MGD)  East/West Clarifiers  Secondary Treatment (135 MGD)  20 Aeration Tanks  4 Quadrants of 5 Tanks  6 Final Clarifiers  Sludge Thickening  8 Gravity Units  Sludge Dewatering  4 Centrifuges 4 © 2013 O’Brien & Gere Frank E. Van Lare WWTP, Monroe County, NY Aeration Tanks  High Rate Activated Sludge  1.5-2.5 hours HRT  14 to 18 tanks in service (varies seasonally)  Monitor for nitrate and control F:M to minimize 30 manual gate valves 5 © 2013 O’Brien & Gere Frank E. Van Lare WWTP, Monroe County, NY Aeration Basis of Design • Max: 290 MGD Flow • Avg: 150 MGD (PE, RAS, Recycle) • Min: 95 MGD • Max: 180,000 lb/d BOD 5 • Avg: 95,000 lb/d Load • Min: 50,000 lb/d 6 © 2013 O’Brien & Gere Oxygen Transfer Testing Old Aeration Tank Configuration  Field measurements  Structural integrity  Complete mix  Oxygen transfer efficiency › 1.8 lb/hp-hr › 61% of clean water (a) © 2013 O’Brien & Gere Aeration Efficiency in High Rate Systems  High Rate Systems  Low oxygen transfer efficiency  Fine bubble has less turbulence  Interference of soluble BOD (surfactants)  Solution  High sBOD gradient  Tank configuration © 2013 O’Brien & Gere Improved Oxygen Transfer Efficiency for Fine Bubble Aeration A Solution  Add anaerobic selector  Modify configuration to plug flow  Extend piping  Close 2 effluent sluice gates © 2013 O’Brien & Gere Phase 1 Improvements Phasing Aeration Tank Upgrades 10 © 2013 O’Brien & Gere