SPWSTAC 2006 From POU to Centralized Arsenic Treatment: A Small Water System Case Study 2006 NGWA Naturally Occurring Contaminants Conference J. Mitchell Spear, Charles A. Cole, Yuefeng Xie and Alison Shuler Penn State Harrisburg

Objective  Conduct an evaluation of a POU device for removal of arsenic in a small public water system to determine the feasibility and cost effectiveness with respect to a similar centralized treatment technology. SPWSTAC 2006

POU vs. Centralized Treatment The advantages of decentralized (POU) treatment in small public water systems. 1) Lower capital cost 2) Treating only water for consumption (approx percent total water) 3) No highly skilled operators needed 4) Waste disposal not a problem 5) Cost saving in smaller systems SPWSTAC 2006

POU vs. Centralized Treatment The advantages of centralized treatment in small public water systems 1) Treats all water 2) Lower annual costs 3) Little customer involvement 4) Cost saving in larger systems SPWSTAC 2006

POU vs. Centralized Treatment Cost Comparison Most studies estimated this number is between 100 to 200 connections SPWSTAC 2006

Overview  Community Selection  Treatment Technology Selection  POU Installations  Arsenic Removal Results  POU Costs  Centralized Treatment Installation and Costs  Summary SPWSTAC 2006

Background System selection  Within US EPA Region III  CWS – primarily residential  Arsenic Concentration (10 µg/L<[As]<50 µg/L )  Population less than 500  Service connections (between )  No plan to meet upcoming MCL SPWSTAC 2006

Background System selection  Mohrsville, PA Population size375 Service Connections125 Production (GPD)17000 Storage Capacity (Gallons) Wells1 Disinfectant12.5% sodium hypochlorite SPWSTAC 2006

Water Quality Characteristics ParameterUnits pH7.3 Arsenic, total28.6 µg/L Chlorine residual mg/L Alkalinity86.0 mg/L Total solids220 mg/L Total dissolved solids216 mg/L Calcium37.5 mg/L Magnesium8.05 mg/L Iron80.0 µg/L Manganese40.0 µg/L SPWSTAC 2006

Treatment Selection General Factors to Consider  Water Chemistry  S.S., Iron, pH, organics, bacteria  Infrastructure Constraints  Available space, electricity, sewer  Permitting Constraints  Labor  Availability and skill SPWSTAC 2006

Treatment Technology Selection  Ability to treat both As +3 and As +5  NSF 61 approval  NSF 53 approval  Residuals (TCLP and WET)  Ability to scale up (POU to Central treatment) --- Isolux™ - Magnesium Elektron, Inc. (Zirconium hydroxide adsorptivemedia) SPWSTAC 2006

Installations POU Treatment Design SPWSTAC 2006

Installations SPWSTAC 2006

POU Pilot Test Result SPWSTAC 2006

Monitoring Results on all POUs by GFAA SPWSTAC 2006

Monitoring Results by Flowmeter Flow (gal/min)Gallons Treated Mean Median Minimum0.390 Maximum SPWSTAC 2006

POU Piloting Costs (1 st year) ItemDollar amount Installation POU system T-valve 6.50 Housing Pre filter (2X/year) Carbon Filter (2X/year) Isolux™ Flow Meter Field testing (2X) 6.00 Compliance testing Operation & Maintenance* Total

POU Annual Cost Capital Costs $ 2004 Installation90.00 T-Valve6.50 Housing95.00 Flow meter42.00 Total % for 10 years Total (yearly)31.73 Total (monthly)2.64 SPWSTAC 2006 Operating Costs $ 2004 Pre-filter18.00 Carbon filter36.00 Isolux™70.00 Field testing6.00 Compliance15.00 O & M Total (yearly) Total (monthly)28.75 Total - $31 / unit / month

POU Acceptance?  25 Pa. Code § Acceptable design.  (e) Point-of-use devises which are treatment devices applied to a single tap are not an acceptable treatment methods for complying with an MCL or treatment technique requirement. SPWSTAC 2006

Centralized Treatment  75 gpm Treatment System w / 100% redundancy  Two 48 x 6 inch towers – 2 inch inlet and outlet  1 Flow meter / totalizer  Particulate prefilter housing  36 – 42 inch Isolux removal cartridges  3 hp booster pump SPWSTAC 2006

Centralized Treatment Annual Cost Capital Costs $ 2006 Treatment Modules Transportation200 Cartridges (36)6480 Start up and Training 2880 Total % for 10 years76848 Total (yearly)7684 SPWSTAC 2006 Total - $9 / connection / month Operating Costs $ 2006 Cartridges5913 Particulate Filter139 Transportation150 Media Management175 Total (yearly)6377 Total Capital + Operating (yearly) 14061

Estimated Monthly Cost Comparison Type of SystemCost/Connection POU $15 - $31 Centralized $9* Treatment * Based on proposal for Isolux media, does not include additional time for operations SPWSTAC 2006

POU vs. Centralized Treatment Cost Comparison SPWSTAC 2006

User Survey Results  Amount willing to pay for POU (monthly)  Average $5  Minimum $0  Maximum $8  Amount willing to pay for centralized treatment (monthly)  Average $10  Minimum $0  Maximum $32 SPWSTAC 2006

Initial “hurdles”  Financial  Water association vs. public water utility  Water association awarded special allowance grant  Permitting  Contracted with licensed engineer for state permitting and overall site plan design  Site Location  No Available space near well house SPWTAC 2006

Current Status  Proposal submitting to Pa DEP  Site plan accepted by Association Board  Contractors designated for site work  Targeted start up – March 2006 SPWSTAC 2006

Summary  POU effective for removing arsenic  Might be more economical solution in very small water systems  Record keeping, communication, increased sampling  Centralized Treatment chosen for Mohrsville site SPWSTAC 2006

Acknowledgements  US EPA Small Public Water Systems Technology Assistance Center Grant for funding the study  Magnesium Elektron, Inc. and Jim Knoll for their technical guidance  Alice Renshaw (President of Mohrsville Water Association) for her cooperation  All participating homeowners SPWSTAC 2006

Contact Information US EPA Small Public Water System Technology Assistance Center J. Mitchell Spear Laboratory Supervisor, ETC (717) SPWSTAC 2006