“Green” & Sustainable Infrastructure: A Water Treatment Perspective Michael R. Schock USEPA,...

“Green” & Sustainable Infrastructure: A Water Treatment Perspective

“Green” & Sustainable Infrastructure: A Water Treatment Perspective

Michael R. SchockUSEPA, ORD, NRMRL, WSWRD

Cincinnati, OHschock.michael@epa.gov

Michael R. SchockUSEPA, ORD, NRMRL, WSWRD

Cincinnati, OHschock.michael@epa.gov

Why Do We Care about Plumbing?

• Human health Toxic contaminants

• Metals• Microorganisms• Organic leachates

Allergens• Dermal irritants (eg. Ni)• Biofilms

Why Do We Care about Plumbing?

• Materials longevity Uniform corrosion (wears through) Non-uniform corrosion

• pinhole leaks• tuberculation

Scale View of Drinking Water Distribution

• Municipal distribution network Mains Storage tanks/reservoirs

• Service lines • Premise plumbing system

Cold (drinking/consumption) Hot (human use)

“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.

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

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

What Are Contamination Sources?

• Pipes• Faucets• Flow control/shut-off valves• Meters• Pressure regulators• Backflow preventers• Storage tanks• Biofilms growing in the above

Pipe Networks Are Not Inert!

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

Example: Copper Levels and Stagnation

Stagnation time, hours

0 10 20 30 40 50 60 70 80 900

1

2

3

4

5

6

7Cu, 161-184 days

DO, 161-184 daysCu, 455-462 days

DO, 455-462 days

Dissolved oxygen

Copper

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

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

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

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

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

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

“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)