Alexander Matthew T, Woodruff Peyton, Mistry Jatin H, Buse Helen Y, Muhlen Christy, Lytle Darren A, Pressman Jonathan G, Wahman David G
United States Environmental Protection Agency, Office of Ground Water and Drinking Water, Standards and Risk Management Division, Technical Support Branch, Cincinnati, Ohio, USA.
Oak Ridge Institute of Science and Education, Oak Ridge, Tennessee, USA.
AWWA Water Sci. 2024 Jun 20;6(3). doi: 10.1002/aws2.1377.
Chloraminated drinking water systems commonly use free chlorine conversions (FCCs) to prevent or control nitrification, but unintended water quality changes may occur, including increased disinfection by-product and metal concentrations. This study evaluated water quality in a chloraminated drinking water system and residential locations before, during, and after their annual, planned FCC. Water quality alternated between relatively consistent and variable periods when switching disinfectants. During the FCC, regulated four trihalomethane and five haloacetic acid concentrations increased by four and seven times, respectively, and exceeded corresponding maximum contaminant levels. Implications of disinfection by-product sampling during an FCC were assessed, and an approach to account for increased FCC disinfection by-product concentrations was proposed. For metals, the FCC had minor impacts on distribution system concentrations and did not appear to impact residential concentrations. Overall, observed variable water quality appeared primarily associated with switching disinfectants and depended on distribution system hydraulics.
氯化消毒饮用水系统通常采用游离氯转化（FCC）来预防或控制硝化作用，但可能会出现意外的水质变化，包括消毒副产物和金属浓度增加。本研究评估了一个氯化消毒饮用水系统以及居民点在年度计划FCC之前、期间和之后的水质。在切换消毒剂时，水质在相对稳定和变化的时期之间交替。在FCC期间，四种受监管的三卤甲烷和五种卤乙酸浓度分别增加了四倍和七倍，并超过了相应的最大污染物水平。评估了FCC期间消毒副产物采样的影响，并提出了一种考虑FCC消毒副产物浓度增加的方法。对于金属，FCC对配水系统浓度影响较小，似乎也不会影响居民点的金属浓度。总体而言，观察到的水质变化主要似乎与消毒剂切换有关，并取决于配水系统的水力情况。
