Minimize Perchlorate Formation in Hypochlorite Solutions

This article discusses a study by the Southern Nevada Water Authority that investigated the rate of perchlorate and other oxyhalide species formation in hypochlorite solutions. The motivation for the study came from the recently proposed Drinking Water System Security Act of 2009 (H.R. 3258) that could decrease the usage of chlorine gas at water and wastewater utilities and increase hypochlorite use. The study discusses the risks and tradeoffs of certain processes in order to avoid problems related to competing compliance standards. The article presents study findings and implications, and makes recommendations on the following topics: dilution on delivery; storage temperature; control pH after dilution; use solutions as soon as possible; control removal of transition metal ions; storage time; and, minimize bromate in brine.