Drinking water is one of the fundamental pillars of modern society. It is crucial that community drinking water meets the highest possible standards & safety regulations. Currently one third of all drinking water in the U.S. is being disinfected using bulk or on-site hypochlorite generation methods. It is expected for this to be a primary method of disinfection in the foreseeable future. Disinfection using sodium hypochlorite produces the presence of chlorate, which is considered a health risk to humans in high concentrations. In the generation process hypochlorite undergoes a disproportionation reaction to form chlorate due to its thermodynamically favorable mechanism. Even though the Environmental Protection Agency (EPA) has not yet regulated the allowable amount of chlorate in public drinking water, the agency has released a Health Risk Limit (HRL). According to results obtained from the EPA’s Unregulated Contaminant Rule 3 (UCMR3), over 38% of Public Water Systems had results above the HRL. Therefore, it is important to track current concentrations of chlorate as well as develop methods to efficiently reduce chlorate concentrations in generated hypochlorite solutions and most importantly, drinking water. The purpose of this research is to consider three parameters that have been determined in previous papers as major contributor to chlorate formation in the post-generation process: pH, temperature and storage time. The goal of this research is to provide a general guideline on how to reduce or eliminate chlorate concentrations during on-site generation processes. Effects are expected to be seen before and after the hypochlorite generation in on-site generators by varying pH levels, temperature and storage turn-over time (only after the hypochlorite generation).

Chlorate formation in on-site hypochlorite generators: Dependence on pH-level, temperature and storage time

253rd National Meeting (2017)

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