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EVALUATING THE IMPACT OF WATER CHEMISTRY ON CUPROSOLVENCY AND COPPER CORROSION BY-PRODUCT USING A SIMPLE COPPER PIPE RECIRCULATING LOOP SYSTEM
Citation:
O'Donnell, A. J. AND D. A. Lytle. EVALUATING THE IMPACT OF WATER CHEMISTRY ON CUPROSOLVENCY AND COPPER CORROSION BY-PRODUCT USING A SIMPLE COPPER PIPE RECIRCULATING LOOP SYSTEM. Presented at Fifth Annual EPA Drinking Water Workshop on Treatment and Distribution System Compliance Challenges, Cincinnati, OH, August 05 - 07, 2008.
Impact/Purpose:
INFORMATION
Description:
1991, EPA publicized the Lead and Copper Rule (LCR),which set regulations to minimize the amount of lead copper in drinking water. The LCR set the copper action level at 1.3 mg/L in more then 10% of customer’s first-draw taps sampled. Potential health effects of copper include vomiting, diarrhea, nausea, and copper toxicity in people with liver damage or Wilson’s disease. Elevated copper levels can come from excessive corrosion of copper pipes and can lead to pinhole leaks and pipe failure. Water chemistry has a large impact on the types of corrosion develop and copper solubility. Phosphate-based chemicals (ortho-, poly-, and blendedphosphates) have been used to control lead solubility and iron precipitation in many drinking water systems. The usefulness of orthophosphate to reduce copper release and oxidant demand has been recognized. The mechanism(s) by which orthophosphate works is not well defined and the effect of polyphosphates on copper corrosion and copper release is less clear. Polyphosphates have many formulations available and are commonly used to stabilize particles (e.g., Ca, Fe, Mn.) Polyphosphates potentially impact the mobility of copper particles and some work has shown that polyphosphates can increase metal levels in water. There is some preliminary work however that suggests that polyphosphates may be beneficial in preventing pitting corrosion of copper. The objective of this work is to better understand the effect of phosphates on copper corrosion and release in water.