以管壁生物膜为前体物的DBPs生成特性和毒性评估

Formation of Disinfection Byproducts from Pipe Wall Biofilm and Their Toxicity Evaluation

针对球墨铸铁管、钢管和聚乙烯(PE)管3种常见给水管材,探究管壁生物膜在氯化作用下生成典型含碳消毒副产物(C-DBPs)和含氮消毒副产物(N-DBPs)的潜能,考察消毒剂投加量对消毒副产物(DBPs)产生的影响,进一步评估管壁生物膜作为DBPs前体物潜在的毒理学危害。结果表明,与主体水相比,管壁生物膜的DBPs生成潜能(DBPFP)更具优势。氯投加量对不同管材生物膜生成C-DBPs和N-DBPs的影响规律有所区别。随着投氯量的增加,三卤甲烷(THMs)和卤乙酸(HAAs)生成量均持续增大;球墨铸铁管生物膜的N-DBPs生成量先增大后减小;钢管和PE管生物膜的二氯乙腈(DCAN)和二氯乙酰胺(DCAcAm)生成量呈现先上升后下降的趋势,三氯硝基甲烷(TCNM)生成量保持增大的趋势。毒性评估结果表明,在较高投氯量下,生物膜的毒性生成潜能更高;但持续增加投氯量,毒性生成潜能有所下降或增势减缓。相比C-DBPs,N-DBPs在生物膜毒性生成潜能上占据更高贡献率,降低生物膜细胞毒性风险的关键是控制DCAN和HAAs,规避遗传毒性风险的核心是防控TCNM的生成。

This paper investigated the potential of biofilm attached on three common water supply pipe walls(ductile iron,steel,and polyethylene)to generate typical carbonaceous disinfection byproducts(C-DBPs)and nitrogenous disinfection byproducts(N-DBPs)under the effect of chlorination,explored the effect of disinfectant dosage on disinfection byproducts(DBPs),and further evaluated the potential toxicological hazards of the pipe wall biofilm as DBPs precursors.The DBPs formation potential(DBPFP)of the pipe wall biofilm was more advantageous than that of the bulk water.The effect of chlorine dosage on C-DBPs and N-DBPs formation from different pipe wall biofilm was distinct.The yield of trihalomethane(THMs)and haloacetic acid(HAAs)increased with the increase of chlorine dosage.The N-DBPs production from ductile iron wall biofilm increased first and then decreased.The production of dichloroacetonitrile(DCAN)and dichloroacetamide(DCAcAm)generated from the steel and PE iron wall biofilm increased first and then decreased,while the production of trichloronitromethane(TCNM)kept increasing.The toxicity evaluation showed that the toxicity formation potential of pipe wall biofilm was higher at high chlorine dosage.However,the toxicity formation potential displayed a slower growth trend or a decrease tendency with the continuous increase of chlorine dosage.Compared with C-DBPs,N-DBPs had a higher contribution rate to the toxicity formation potential of pipe wall biofilm.The key to reduce the pipe wall biofilm cytotoxicity risk was to control DCAN and HAAs,and the core to avoid the genotoxicity risk was to prevent the formation of TCNM.