1 Reducing THM via Aeration: A Case Study August 28, 2014 by Gary Williams, P.E. Jones & Henry Engineers WEA-AWWA 2014 Technical Conference & Expo Agenda 2 Location  History  Pilot  Implementation  Take Away Information  Location Map 3 Water Quality 2008 4 Raw Water Total Hardness 285 mg/L as CaCO 3 Total Alkalinity 133 mg/L as CaCO 3 pH 8.2 Turbidity 3.2 Total Organic Carbon 4.5 mg/L Finished Water Total Hardness 150 mg/L as CaCO 3 Total Alkalinity 36 mg/L as CaCO 3 pH 9.2 Total Organic Carbon (average) 2.1 mg/L TOC Removal (average) 51% THM 2008 5 Total Trihalomethane & HAA5 2007/2008 Date of Sample Location Second MR002 HAA5 Sample Quarter 2007 Average RAA LRAA Average RAA 5/24/2007 RD002 38.9 13.4 RD003 40.8 14.4 MR002 50.2 43.3 47.8 59.3 11.8 13.2 17.8 Thrid Quarter 2007 7/10/2007 RD002 82.3 16.6 RD003 85.3 15.2 MR002 102.0 89.9 50.4 60.6 16.7 16.2 14.4 Fourth Quarter 2007 10/11/2007 RD002 54.1 17.3 RD003 58.3 16.4 MR002 81.7 64.7 58.1 69.3 22.0 18.6 15.9 First Quarter 2008 1/16/2008 RD002 40.6 19.3 RD003 40.7 20.8 MR002 54.9 45.4 60.8 72.2 20.4 20.2 17.0 Second Quarter 2008 4/2/2008 RD002 40.5 13.6 RD003 40.6 13.1 MR002 60.3 47.1 61.8 74.7 14.2 13.6 17.1 Third Quarter 2008 7/8/2008 RD002 85.1 33.1 RD003 85.3 32.1 MR002 131.0 100.5 64.4 82.0 34.7 33.3 21.4 Fourth Quarter 2008 10/9/2008 RD002 52.0 28.8 RD003 55.7 28.8 MR002 80.6 62.8 63.9 81.7 33.3 30.3 24.4 Water History 6 1972 Water Treatment Plant, Low Head Dam, and  Reservoir Constructed 1993 Water Treatment Plant Study  1996 Reservoir Study  1999-2000 Water Treatment Plant Expansion $3,000,000  2002 Second Reservoir $2,300,000  2004 Water Distribution System DBP Reduction Study  2005 Chlorine Dioxide Benchtop Study  2005 MIEX Benchtop Study  2006 RSSCT for GAC Benchtop Study  2008 THM Reduction via Aeration Opflow Article  2008 THM Reduction via Aeration Opflow Article 7 Research 8 Limited Research Available for Dynamic System  One Company Marketed a System $$$$$$$$  Air : Water Ratios (cfm : gpm) 5 to 60  If A:W = 40 and processing water @ 700 gpm =  28,000 cfm blower Approximately 200 hp Blower  Pilot 9 Assumed 20:1 A:W ratio or 14,000 cfm  Determined Approximate Area Diffusors for 14,000 cfm in  Clearwell 2 Assumed One/half Depth of Clearwell or 7 feet  Calculated the Volume over the Diffusors  Developed the Detention Times in the Three Celled  Clearwell Influent Cell 60 minutes  Aeration Cell 75 minutes  Effluent Cell 60 minutes  Scaled down the flows of air and water to match a 4-inch  PVC pipe Pilot 10