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“Green” & Sustainable Infrastructure: A Water Treatment Perspective

“Green” & Sustainable Infrastructure: A Water Treatment Perspective. Michael R. Schock USEPA, ORD, NRMRL, WSWRD Cincinnati, OH schock.michael@epa.gov. Why Do We Care about Plumbing?. Human health Toxic contaminants Metals Microorganisms Organic leachates Allergens

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“Green” & Sustainable Infrastructure: A Water Treatment Perspective

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  1. “Green” & Sustainable Infrastructure: A Water Treatment Perspective Michael R. Schock USEPA, ORD, NRMRL, WSWRD Cincinnati, OH schock.michael@epa.gov

  2. Why Do We Care about Plumbing? • Human health • Toxic contaminants • Metals • Microorganisms • Organic leachates • Allergens • Dermal irritants (eg. Ni) • Biofilms

  3. Why Do We Care about Plumbing? • Materials longevity • Uniform corrosion (wears through) • Non-uniform corrosion • pinhole leaks • tuberculation

  4. Scale View of Drinking Water Distribution • Municipal distribution network • Mains • Storage tanks/reservoirs • Service lines • Premise plumbing system • Cold (drinking/consumption) • Hot (human use)

  5. “Premise Plumbing” • After NRC-NAS Report1 definition • Residential • School/day care • Hospital • Office building • Manufacturing complex 1 National Research Council, 2006. Alternatives for Premise Plumbing. Ch. 8 in: Drinking Water Distribution Systems: Assessing and Reducing Risk, pp. 316-340. National Academies Press, Washington, DC.

  6. Typical Plumbing Materials: DS • Old unlined iron • Asbestos-cement • Cement mortar linings with seal coat • Bitumen • Epoxy • Plastics • In-situ relined (rehabilitated) • Cement mortar • Epoxy • Plastic liners

  7. Typical New Premise Plumbing Materials • Copper • Plastics • Copper alloy components • Traditional leaded brasses • New low-Pb alloys • Stainless steels • Plated materials (Ni, Cr) • Soldered joints

  8. What Are Contamination Sources? • Pipes • Faucets • Flow control/shut-off valves • Meters • Pressure regulators • Backflow preventers • Storage tanks • Biofilms growing in the above

  9. Pipe Networks Are Not Inert!

  10. Challenges of Water Conservation • Creates conditions of • Higher metal exposure potential • Depletion of disinfection • Temperature conditions favorable for nitrification and other biofilm growth • Problem extent function of: • Background water chemistry • Usage pattern • Spatial distribution of contamination sources

  11. Example: Copper Levels and Stagnation

  12. Current Plumbing Standards • EPA does not have statutory authority to require non-contaminating materials not be used in drinking water systems • SDWA has voluntary standards • Widespread use of NSF/ANSI 61 in model plumbing codes • Enforcement erratic or non-existent

  13. More Problems • Standards not robust enough to cover low-flow challenges • Many materials are legal under the standards, but can still contaminate under many water chemistries • Leaded brasses • Copper

  14. DW Treatment Dilemma • Water chemistry targets of corrosion control often conflict with ideal conditions for DBP control • Increasing levels of disinfectant to overcome high water age cause more DBPs to form • High dosages of corrosion inhibitors create high nutrient loads for wastewater treatment plants • Phosphate inhibitors are costly and sometimes in short supply

  15. Reasons to Avoid Supplemental Building Water Treatment • Dangerous chemicals • Requires chemical feed or other mechanical equipment operation • Ongoing chemical/process cost • Requires dosage and background chemistry monitoring to maintain proper conditions • May require licensed operator and state or federal regulation as TNCWS • Even POU devices at each tap for consumption require monitoring and replacement

  16. What We Think is “Green” • Reduced use of non-renewable natural resources • Manufacture of plumbing materials • Municipal or supplemental DW treatment chemicals • Does not cause unhealthy levels of contamination under intended usage conditions • Metals • Organics • Microbial

  17. What We Think is “Green” • Does not require supplemental treatment • Entry point • Point of use • Does not create environmental challenges with waste • Reduces metal loadings to WWTPs • Reduces nutrient loadings to WWTPs • Plumbing materials amenable to recycling/reuse

  18. “Green Infrastructure”New Opportunity for Achievable Objectives • Prevent the potential for contamination in the first place • Dramatically reduce the extent of contamination • Simplify central water treatment to provide better overall protection • Metal contamination • Corrosion • Disinfection • Disinfection byproducts (carcinogens)

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