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QUENCHING OF CHLORINATION DISINFECTION BY-PRODUCT FORMATION IN DRINKING WATER BY HYDROGEN PEROXIDE. (R825362)
Citation:
Batterman, S., L. Z. Zhang, AND S. Q. Wang. QUENCHING OF CHLORINATION DISINFECTION BY-PRODUCT FORMATION IN DRINKING WATER BY HYDROGEN PEROXIDE. (R825362). WATER RESEARCH. American Chemical Society, Washington, DC, 34(5):1652-1658, (2000).
Description:
Reactions between chlorine disinfectants, dissolved organic matter, and other chemicals in water form a series of disinfection by-products (DBPs), including trihalomethanes (THMs) and haloacetic acids (HAAs), that are toxic and subject to increasingly stringent regulations. This paper explores effects on DBP formation produced by an alternative, non-chlorine-based secondary disinfectant comprised of silver and hydrogen peroxide (Ag+/H2O2) that is designed to provide long-lasting residual disinfection. Based on a series of laboratory experiments using simulated treatment and distribution systems, post-chlorination additions of the secondary disinfectant dramatically reduced the formation of halogenated DBPs. Five source waters were tested over a range of conditions, including various levels of chlorine dosing, bromine and organic carbon concentrations, pH and temperature. For surface and ground waters, DBP reductions at 24 h with the secondary disinfectant averaged 72±9% for THMs and 67±11% for HAAs after a 10-min chlorination period. The dramatic reduction in halogenated DBPs occurred for all tested source waters and all disinfection conditions. The likely mechanism is the reduction of chlorine to chloride by H2O2, which halts further reaction of chlorine with dissolved organic matter and other DBP precursors. Thus, H2O2 acts as a quenching agent, in addition to its residual disinfectant properties in combination with Ag+. This research shows a potential benefit of mixed disinfectants that provide a potentially viable option for controlling the formation of DBPs while maintaining effective disinfection.
Author Keywords: disinfection; disinfection by-products; drinking water; haloacetic acids; hydrogen peroxide; silver; trihalomethanes