Glenn W. Holden
Use of chlorine dioxide (ClO2) in surface water treatment plants has grown significantly as regulations addressing disinfection byproduct (DBP) formation have become increasingly stringent over the last two decades. For example, the US Environmental Protection Agency’s (USEPA’s) Stage 2 Disinfectants and Disinfection Byproducts Rule (DBPR) requires systems to identify locations within their distribution systems with high levels of DBPs to serve as sampling sites. Water systems must meet the maximum contaminant levels (MCLs) for total trihalomethanes at 0.08 mg/L and the sum of five haloacetic acids at 0.06 mg/L, taken as an average at each monitoring location (a locational running annual average) instead of as a system-wide average as allowed under the Stage 1 DBPR.
To comply with more stringent DBP regulations, many surface water treatment plants needed to change their DBP control strategies, including preoxidation with ClO2. Because of its selective reactivity, in comparison with chlorine and other oxidizing agents, ClO2 is effective in controlling waterborne pathogens while minimizing halogenated DBPs. ClO2 is a broad-spectrum microbiocide; as effective as chlorine against viruses, bacteria, and fungi; and more effective than chlorine for the inactivation of the encysted parasites Giardia and Cryptosporidium parvum (Chauret et al. 2001). ClO2 is also an effective control strategy for taste, odor, color, iron, and manganese removal (Stevens 1982, Mounsey & Hagar 1946).
Continue reading this AWWA Journal Article to learn more, including three specific case study examples in Texas, California and Arkansas.
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Author: Glenn W. Holden, Business Development and Corporate Accounts Manager, Evoqua Water Technologies
Source: AWWA Journal Article, Chlorine Dioxide Preoxidation for DBP Reduction, July 2017
