Precursors of typical nitrogenous disinfection byproducts: Characteristics, removal, and toxicity formation potential.
Precursors of typical nitrogenous disinfection byproducts: Characteristics, removal, and toxicity formation potential.
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DOI：
10.1016/j.scitotenv.2020.140566
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发表时间：
2020-07
期刊：
影响因子：
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通讯作者：
Shisheng Zhang;Tao Lin;Han Chen;Hang Xu;W. Chen;Hui Tao
中科院分区：
文献类型：
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作者：
Shisheng Zhang;Tao Lin;Han Chen;Hang Xu;W. Chen;Hui Tao
饮用水中氮消毒副产物(N-DBPs)的出现已成为人们普遍关注的问题。本研究以二氯乙腈(DCAN)、二氯乙酰胺(DCAcAm)和三氯硝基甲烷(TCNM)为代表，研究了太湖、长江和高邮湖原水中N-DBP前体的特征。脱除DCAN和DCAcAm前体必须集中在非极性和带正电的有机物上，但作为TCNM前体的小分子、极性和非带正电的有机物应该受到更多的关注。与分子量分级和亲水性分级相比，极性分级和电学分级对N-DBP前体具有更高的选择性。N-DBP前体的性质在水系统中相对固定和可追踪，这可能有助于它们的定向去除。在考察其特性的基础上，研究了三个饮用水处理厂(DWTP)在不同工艺条件下对有机前体的去除效果和选择性。预臭氧化产生的TCNM前体可以在混凝过程中被有效去除。常规工艺对N-DBP前驱体的累积去除效率约为20-30%，但臭氧/生物炭工艺的去除效率提高了约40%。提高O_3/BAC对N-DBP前体的去除效率的关键是对低分子量、非极性、带正电荷、亲水性和透水性有机物的有效去除。在联合毒性试验中，当DCAN、DCAcAm和TCNM共存时，细胞毒性和遗传毒性都表现出协同效应，这意味着实际水体中的低水平毒性增强值得关注。毒性形成势(TFP)以DCAN前体为主，TCNM前体次之。此外，总N-DBP前体的去除速率可能高于TFP，导致在水处理实践中对前体去除的评估过于乐观。因此，还必须考虑对TFP的去除效果。
The emergence of nitrogenous disinfection byproducts (N-DBPs) in drinking water has become a widespread concern. In this study, dichloroacetonitrile (DCAN), dicholoacetamide (DCAcAm) and trichloronitromethane (TCNM) were chosen as representatives to clarify the characteristics of N-DBP precursors in the raw waters of Taihu Lake, the Yangtze River, and Gaoyou Lake. Removal of DCAN and DCAcAm precursors must focus on nonpolar and positively charged organics, but more attention should be paid to micromolecular, polar and non-positively charged organics as TCNM precursors. Compared to molecular weight (MW) and hydrophilicity fractionation, polarity and electrical classification have higher selectivity to intercept N-DBP precursors. The properties of N-DBP precursors are relatively fixed and traceable in water systems, which could contribute to their targeted removal. Based on investigation of their characteristics, the removal efficiency and preferences of organic precursors under different processes were studied in three drinking water treatment plants (DWTPs). The TCNM precursors produced in preozonation can be effectively removed during coagulation. The cumulative removal efficiency of conventional processes on N-DBP precursors was approximately 20–30%, but O3/BAC process improved removal by about 40%. The key to improving the removal efficiency of N-DBP precursors by O3/BAC is that it can significantly remove low-MW, nonpolar, positively charged, hydrophilic and transphilic organics. In combined toxicity trials, both cytotoxicity and genotoxicity showed a synergistic effect when DCAN, DCAcAm, and TCNM coexisted, which means that low-level toxicity enhancement in the actual water merits attention. DCAN precursors dominated in the toxicity formation potential (TFP), followed by TCNM precursors. In addition, the removal rate of total N-DBP precursors may be higher than that of TFP, leading to overly optimistic evaluation of precursor removal in water treatment practice. Therefore, the removal effect on TFP must also be considered.