The Effects of NOM and Coagulation on Copper Corrosionby John P. Rehring, Univ of Colorado, Boulder, CO, USA,
Marc Edwards, Univ of Colorado, Boulder, CO, USA,
Abstract: Copper corrosion was examined in solutions containing natural organic matter (NOM) and in situations where NOM was removed by enhanced coagulation with alum or ferric chloride. Electrochemical methods were used to evaluate the long-term effects of each water quality on copper corrosion. In experiments exploring the role of NOM in copper corrosion, corrosion rates increased with NOM concentration at pH 6, whereas at pH 7.5 and 9 the NOM had less significant effects. Waters treated by enhanced alum coagulation had higher corrosion rates than untreated waters, but enhanced ferric chloride coagulation had the opposite effect. This difference was attributed to the relative effects of added sulfate via alum coagulation versus added chloride via ferric chloride coagulation. Compliance with the EPA Lead and Copper Rule and disinfection byproduct regulations may require that utilities address both regulations simultaneously. That is, water treatment processes, NOM concentration, and copper corrosion behavior are clearly interdependent and should be considered when contemplating changes to meet DBP regulations.
Subject Headings: Organic matter | Corrosion | Copper (chemical) | Coagulation | Chloride | Water quality | pH
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