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SPWSTAC 2006

Study on POU versus centralized treatment for arsenic removal in small water systems, comparing costs and effectiveness.

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SPWSTAC 2006

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  1. 2006 NGWA Naturally Occurring Contaminants Conference From POU to Centralized Arsenic Treatment: A Small Water System Case Study J. Mitchell Spear, Charles A. Cole, Yuefeng Xie and Alison Shuler Penn State Harrisburg SPWSTAC 2006

  2. 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

  3. 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. 10- 40 percent total water) 3) No highly skilled operators needed 4) Waste disposal not a problem 5) Cost saving in smaller systems SPWSTAC 2006

  4. 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

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

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

  7. 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 30 - 200) • No plan to meet upcoming MCL SPWSTAC 2006

  8. Background System selection • Mohrsville, PA SPWSTAC 2006

  9. Water Quality Characteristics SPWSTAC 2006

  10. 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

  11. 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 adsorptive media) SPWSTAC 2006

  12. Installations POU Treatment Design SPWSTAC 2006

  13. Installations SPWSTAC 2006

  14. POU Pilot Test Result SPWSTAC 2006

  15. Monitoring Results on all POUsby GFAA SPWSTAC 2006

  16. Monitoring Resultsby Flowmeter SPWSTAC 2006

  17. POU Piloting Costs (1st year)

  18. POU Annual Cost Total - $31 / unit / month SPWSTAC 2006

  19. POU Acceptance? • 25 Pa. Code § 109.602 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

  20. 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

  21. Centralized Treatment Annual Cost Total - $9 / connection / month SPWSTAC 2006

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

  23. POU vs. Centralized Treatment Cost Comparison SPWSTAC 2006

  24. 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

  25. 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

  26. 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

  27. 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

  28. 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

  29. Contact Information US EPA Small Public Water System Technology Assistance Center J. Mitchell Spear Laboratory Supervisor, ETC jms63@psu.edu (717) 948-6357 SPWSTAC 2006

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