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Chlorinated Cyanurates in Drinking Water: Measurement Bias, Stability, and Disinfectant Byproduct Formation
Citation:
Wahman, D., M. Alexander, AND A. Dugan. Chlorinated Cyanurates in Drinking Water: Measurement Bias, Stability, and Disinfectant Byproduct Formation. JOURNAL OF THE AMERICAN WATER WORKS ASSOCIATION. American Water Works Association, Denver, CO, 1(2):e1133, (2019). https://doi.org/10.1002/aws2.1133
Impact/Purpose:
Evaluation of issues with measuring free chlorine in systems using chlorinated cyanurates. Since 2001 in the United States, two chlorinated cyanurates, commonly referred to as dichlor (anhydrous sodium dichloroisocyanurate or sodium dichloroisocyanurate dihydrate) or trichlor (trichloroisocyanuric acid) may be approved by states, tribes, or territories for use in drinking water. One complication with dichlor or trichlor is that the actual free chlorine concentration in these systems cannot be accurately measured by currently approved methods. Based on known water chemistry, two possible advantages of dichlor or trichlor use are potential increased residual stability and conversely delayed regulated disinfectant by–product (DBP) formation. To inform these practical considerations, the current research investigated measurement bias in N,N–diethyl–p–phenylenediamine (colorimetric and portable parallel analyzer), indophenol, amperometric titration, and amperometric electrode based free chlorine methods. In addition, hold studies using surface water and either free chlorine, dichlor, or trichlor were conducted to compare disinfectant residual stability and regulated DBP formation.
Description:
Since 2001 in the United States, two chlorinated cyanurates, commonly referred to as dichlor (anhydrous sodium dichloroisocyanurate or sodium dichloroisocyanurate dihydrate) or trichlor (trichloroisocyanuric acid) may be approved by states, tribes, or territories for use in drinking water. One complication with dichlor or trichlor is that the actual free chlorine concentration in these systems cannot be accurately measured by currently approved methods. Based on known water chemistry, two possible advantages of dichlor or trichlor use are potential increased residual stability and conversely delayed regulated disinfectant by–product (DBP) formation. To inform these practical considerations, the current research investigated measurement bias in N,N–diethyl–p–phenylenediamine (colorimetric and portable parallel analyzer), indophenol, amperometric titration, and amperometric electrode based free chlorine methods. In addition, hold studies using surface water and either free chlorine, dichlor, or trichlor were conducted to compare disinfectant residual stability and regulated DBP formation.
URLs/Downloads:
DOI: Chlorinated Cyanurates in Drinking Water: Measurement Bias, Stability, and Disinfectant Byproduct Formation
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