A balancing act: Optimizing free chlorine contact time to minimize iodo-DBPs, NDMA, and regulated DBPs in chloraminated drinking water  

作　　者：Matthew A.Bloodgood Sridevi Anduri Chowdary Eric J.Daiber Honglan Shi Caroline O.Granger Susan D.Richardson 

机构地区：[1]Student Services Authority,U.S.Environmental Protection Agency,National Exposure Research Laboratory,Athens,GA 30605,USA [2]Department of Chemistry,Missouri University of Science and Technology,Rolla,MO 65409,USA [3]Department of Chemistry and Biochemistry,University of South Carolina,Columbia,SC 29208,USA

出　　处：《Journal of Environmental Sciences》2022年第7期315-325,共11页环境科学学报（英文版）

摘　　要：Many drinking water treatment plants in the U.S. have switched from chlorination to chloramination to lower levels of regulated trihalomethane(THM) and haloacetic acid(HAA) disinfection byproducts(DBPs) in drinking water and meet the current regulations. However, chloramination can also produce other highly toxic/carcinogenic, unregulated DBPs: iodoacids, iodo-THMs, and N-nitrosodimethylamine(NDMA). In practice, chloramines are generated by the addition of chlorine with ammonia, and plants use varying amounts of free chlorine contact time prior to ammonia addition to effectively kill pathogens and meet DBP regulations. However, iodo-DBPs and nitrosamines are generally not considered in this balancing of free chlorine contact time. The goal of our work was to determine whether an optimal free chlorine contact time could be established in which iodo-DBPs and NDMA could be minimized, while keeping regulated THMs and HAAs below their regulatory limits. The effect of free chlorine contact time was evaluated for the formation of six iodo-trihalomethanes(iodo-THMs), six iodo-acids, and NDMA during the chloramination of drinking water. Ten different free chlorine contact times were examined for two source waters with different dissolved organic carbon(DOC) and bromide/iodide. For the low DOC water at pH 7 and 8, an optimized free chlorine contact time of up to 1 h could control regulated THMs and HAAs, as well as iodo-DBPs and NDMA. For the high DOC water, a free chlorine contact time of 5 min could control iodo-DBPs and NDMA at both p Hs, but the regulated DBPs could exceed the regulations at pH 7.

关 键 词：Iodo-DBPs NDMA Disinfection byproducts CHLORAMINE Drinking water Free chlorine contact time 

分 类 号：TU991.2[建筑科学—市政工程]