State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China; Ministry of Education Key Laboratory of Yangtze River Water Environment, Tongji University, Shanghai 200092, China.
State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China; Shandong Province Water Supply and Drainage Monitoring Centre, Jinan 250101, China.
Water Res. 2023 Nov 1;246:120692. doi: 10.1016/j.watres.2023.120692. Epub 2023 Oct 3.
The pH of chlorination is an important factor affecting the formation of disinfection byproducts (DBPs). In this study, we discovered that the genotoxicity induced by chlorination can be effectively reduced under alkaline conditions. As the pH of chlorination increased from 6.5 to 8.5, the genotoxicity of investigated waters reduced by ∼30-90 %. By assessing the genotoxicity of the mixture of measured DBPs, it was found that the contribution of measured DBPs to the overall genotoxicity was lower than 5 %, and the significant reduction of genotoxicity was largely associated with unknown DBPs. The result of Pearson's correlation analysis indicated that humified organics and soluble microbial byproducts were likely responsible for the genotoxicity, and their derived genotoxic compounds (i.e., unknown DBPs) tended to decompose during alkaline chlorination. However, the control of genotoxicity by alkaline chlorination was achieved at the expense of promoting trihalomethane (THM) formation. The highest genotoxicity reduction (93 %) was observed for chlorinated granular activated carbon-treated waters, but the formation of THMs was promoted to a level approaching that in untreated waters. The inconsistent trend of overall genotoxicity and THM concentration during alkaline chlorination suggested the inadequacy of THMs as metric for DBP exposure, and considerations should also be given to the toxicity of bulk water in addition to regulated DBPs.
氯化的 pH 值是影响消毒副产物（DBPs）形成的一个重要因素。在本研究中，我们发现氯化在碱性条件下可以有效降低遗传毒性。随着氯化 pH 值从 6.5 增加到 8.5，所研究水样的遗传毒性降低了约 30-90%。通过评估所测 DBPs 混合物的遗传毒性，发现所测 DBPs 对总遗传毒性的贡献低于 5%，而遗传毒性的显著降低主要与未知 DBPs 有关。Pearson 相关分析的结果表明，腐殖化有机物和可溶性微生物副产物可能是遗传毒性的原因，而它们衍生的遗传毒性化合物（即未知 DBPs）在碱性氯化过程中容易分解。然而，碱性氯化对遗传毒性的控制是以促进三卤甲烷（THM）形成的代价实现的。经颗粒活性炭处理的氯化水样观察到最高的遗传毒性降低（93%），但 THM 的形成被促进到接近未处理水样的水平。碱性氯化过程中总遗传毒性和 THM 浓度的不一致趋势表明，THM 不能作为 DBPs 暴露的指标，除了受管制的 DBPs 外，还应考虑原水的毒性。
