State Key Laboratory of Pollution Control and Resource Reuse, Key Laboratory of Urban Water Supply, Water Saving and Water Environment Governance in the Yangtze River Delta of Ministry of Water Resources, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, PR China.
Department of Civil and Environmental Engineering, South Dakota School of Mines and Technology, Rapid City, SD 57701, USA.
Sci Total Environ. 2023 Jul 1;880:163297. doi: 10.1016/j.scitotenv.2023.163297. Epub 2023 Apr 5.
Mixed chlorine/chloramines are common in drinking water distribution systems (DWDSs); however, their transformation and impact on chemical and microbial characteristics are not well understood. We systematically investigated water quality parameters associated with mixed chlorine/chloramine species conversion in 192 samples (including raw, finished, and tap water) collected throughout the year in a city in East China. Various chlorine/chloramine species (free chlorine, monochloramine [NHCl], dichloramine [NHCl], and organic chloramines [OC]) were detected in both chlorinated and chloraminated DWDSs. NHCl + OC increased with transport distance along the pipeline network. The maximum proportion of NHCl + OC in over total chlorine in tap water reached 66 % and 38 % from chlorinated and chloraminated DWDSs, respectively. Both free chlorine and NHCl showed a rapid decay in the water pipe systems, but NHCl and OC were more persistent. Correlations between chlorine/chloramine species and physicochemical parameters were established. Models for predicting the sum of chloroform/TCM, bromodichloromethane/BDCM, chlorodibromomethane/CBDM, and bromoform/TBM (THM) (R = 0.56) and haloacetic acids (HAAs) (R = 0.65) exhibited greater accuracy based on machine learning tuned with chlorine/chloramine species, particularly NHCl + OC. The predominant bacterial communities in mixed chlorine/chloramine systems were those resistant to chlorine or chloramine such as proteobacteria. NHCl was the most significant explanatory factor (28.1 %) for the variation in microbial community assemblage in chloraminated DWDSs. Although residual free chlorine and NHCl + OC, accounted for a smaller proportion of chlorine species in chloraminated DWDSs, they played an essential role (12.4 % and 9.1 %, respectively) in the microbial community structure.
混合氯/氯胺在饮用水分配系统（DWDS）中很常见；然而，它们的转化及其对化学和微生物特性的影响还不太清楚。我们系统地调查了 192 个样本（包括原水、成品水和自来水）中的水质参数，这些样本全年在中国东部的一个城市采集。在氯化和氯胺化的 DWDS 中都检测到了各种氯/氯胺物种（游离氯、一氯胺[NHCl]、二氯胺[NHCl]和有机氯胺[OC]）。NHCl+OC 随着沿管网的输送距离增加而增加。自来水中 NHCl+OC 占总氯的最大比例分别达到了 66%和 38%，来自氯化和氯胺化的 DWDS。游离氯和 NHCl 在水管系统中迅速衰减，但 NHCl 和 OC 更持久。建立了氯/氯胺物种与理化参数之间的相关性。基于机器学习，使用氯/氯胺物种进行调整的模型可以更准确地预测三卤甲烷（THM）（R=0.56）和卤乙酸（HAAs）（R=0.65）的总和，这些模型表现出更好的预测能力。在混合氯/氯胺系统中，主要的细菌群落是那些对氯或氯胺有抵抗力的细菌，如变形菌门。NHCl 是氯胺化 DWDS 中微生物群落组成变化的最显著解释因素（28.1%）。尽管剩余的游离氯和 NHCl+OC 在氯胺化 DWDS 中占氯物种的比例较小，但它们在微生物群落结构中起着重要作用（分别为 12.4%和 9.1%）。
