Basic Steps in DW Treatment Process. Water Treatment. EPA and DBP s. Scottsdale Chaparral DW Plant

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1 Basic Steps in DW Treatment Process Water Treatment DW: Drinking Water (pre use) Vs. WW: Waste Water (post use) Natural Sedimentation Coagulation lime ++ & clay => floc Flocculation time and mixing to max. floc Sedimentation density settling of floc Filtration gravel, sand, charcoal (suspended) Disinfection chlorine or ozone Amendments fluorine HWR213 The University of Arizona 1 HWR213 The University of Arizona 2 Putting it all together Schematic of typical: Drinking Water, Waste Water Treatment processes HWR213 The University of Arizona 3 EPA and DBP s EPA believes that the best way to control Disinfection By Products (DBPs) is both to regulate known byproducts and to limit the quantity of disinfection byproduct precursors (e.g., decomposing plant material) allowed to react with disinfectants. TTHM and HAA5 are useful indicators for measuring DBPs in chlorinated drinking water because they commonly occur at levels that can be easily measured. Enforceable Stds Maximum Contaminant Levels (MCL) Maximum Residual Disinfection Levels (MRDL) Guidelines MCL goals (MCLG) MRDL goals (MRDLG) water.epa.gov/lawsregs/guidance/sdwa/index.cfm Stage 1 (1998) Initial guidance To be done by 2002 Stage 2 (2006) Distribution system hazard analysis To be done by HWR213 The University of Arizona 4 Scottsdale Chaparral DW Plant Contractor: Black Veatech Cost: $78 M Capacity: 30 mgd (2011) Innovation: Microfiltration; Granulated Activated Carbon (GAC) to lower TOC and thus meet Stage 2 DBPR for THM; on site Sodium Hypochlorite gen. HWR213 The University of Arizona 5 HWR213 The University of Arizona 6

2 Scottsdale CAP DW Plant Contractor: Malcolm Pirnie Cost: $100 M (2015) Capacity: 53 >73 >83 mgd (2015) Innovation: Granulated Activated Carbon to lower TOC and thus meet Stage 2 DBPR for THM; on site Sodium Hypochlorite gen. TW Hayden Udall DW Treatment Plant HWR213 The University of Arizona 7 d=680&option=com_content&task=view HWR213 The University of Arizona 8 Yuma Desalination Plant Type: Brackish Water RO Cost: $250 M; $?M annual Output: 90 mgd? Capacity: 70 kafy Power: 45 MW/yr Rate: $1000/af; pwr $35/af Built: 1992 TW Avra Valley Recharge Basins HWR213 The University of Arizona M; $6 M/yr stand by cost Almost never used Pilot test 30% or 21 kaf, cost $23 M Needs $50 M in upgrades HWR213 The University of Arizona 10 Perth Desalination Plant technology.net/projects/perth/ Type: Sea Water Rev. Osmosis Cost: $410 M; $21M annual Output: 140 kl/d = 37 mgd Capacity: 45 GL/y = 36 kafy Power: 4 kwh/l or 24 MW/yr Rate: $4.7/kgal or $1532/af Built: 2006 HWR213 The University of Arizona 11 Basic Steps in the WW Treatment Process Primary Screening Settling Secondary Biological Clarification Tertiary Remove NO 3, P Disinfection: Cl, UV HWR213 The University of Arizona 12

3 Comparison of filtration systems Home: Water softener MF/Pitcher MF/Tap UF RO Other: Tap Bulk H2O Bottled HWR213 The University of Arizona 13 HWR213 The University of Arizona 14 Pima County WW Treatment Plant HWR213 The University of Arizona 15 HWR213 The University of Arizona 16 Ak Chin WWT Plant super clean! Sweetwater Wetlands Tertiary HWR213 The University of Arizona 17 HWR213 The University of Arizona 18

4 Issues with DW Treatment Disinfection Byproducts Cl 2 ==> HCO Dissolved minerals TDS and Hard water (Ca +, Mg ++ ) Costs/Effectiveness Ozone/UV more effective but Chlorine has residual Fluoridation Not everyone thinks its necessary Issues with WW Treatment Use of effluent: Toilet to tap Risks asso. w/ Pharmaceuticals Who owns/gets credit for the water Quality and disposition of RO brackish water HWR213 The University of Arizona 19 HWR213 The University of Arizona 20 Energy demands Water Energy Nexus Energy Cost of 2 nd & 3 rd Treatment Parameter Range of Values Secondary Treat. (kwh/lb BODr) Secondary Treat. (kwh/mg) Oxygen transfer efficiency (OTE) Total Plant (kwh/mg) % Plant used for secondary treat % HWR213 The University of Arizona 21 Parameter Range of Values UV@2000 MPN/L UV (kwh/mg) UV@22 MPN/L UV (kwh/mg) 1001 % Plant used for UV % Cl mg/l Cl 2 (kwh/mg) 256 NaOCl@ 20 mg/l Cl 2 (kwh/mg) PG&E Study: sys/ww/pge2.pdf HWR213 The University of Arizona 22 Low Tech DW Treatment Settling basin HWR213 The University of Arizona 23 Slide from Ahmed

5 Slide from Ahmed Slide from Ahmed As-removal by Fe-filings Nikos Nikolaidis - U. Connecticut Air Coagulation In Out 150 L/day Fe-filings Air bubbler 0.4 m & sand oxidation filter Settling Filtration Fill & Draw Unit (School in Nohakali) Slide from Capdevila HWR 203 The University of Arizona Inflow Water Treated Water ph Eh Cond O 2, mg/l < As, μg/l 600 <50 Fe, mg/l PO4, mg/l 1.4 BDL Source: United States (Columbia U.) and Bangladesh (Dhaka University NIPSOM) Arsenic Project Low Tech WW Treatment Effluent Wetlands Heavy metal reduction HWR213 The University of Arizona 29 HWR213 The University of Arizona 30

6 Apache Nitrogen Site, Benson Nitrate Reduction EPA: in.org/greenremediation/subtab_d16.cfm HWR213 The University of Arizona 31