Abstract：
The issue of biofilm-related disinfection byproducts (DBPs) in drinking water distribution system (DWDS) has garnered significant attention. This study sought to examine the changes in biofilm-originated halogenated DBP formation potential (biofilm DBP-FP) in simulated continuous-flow DWDSs subjected to sequential UV and chlorine disinfection (UV-Cl2) treatments with varying UV doses and to propose the underlying mechanism. The formation potential of trihalomethanes (THMs), haloacetic acids (HAAs), and the total organic halogen (TOX, X = Cl and Br) produced by biofilm were measured. Results showed that the biofilm TOCl-FP was at a minimum with a UV dose of 80 mJ/cm2, corresponding to the lowest amounts of protein and polysaccharides in the extracellular polymeric substances (EPS). Sphingobium, Methylobacterium, and Sphingomonas played a crucial role in protein and polysaccharide biosynthesis. Bacterial community composition characterization together with metabolic function analysis indicated that dominant bacteria varied and metabolic function shifted due to UV-Cl2 disinfection, with Alphaproteobacteria increasing in relative abundance and Bacteroidia showing the opposite trend with increasing UV doses. Correlation analysis suggested that the UV-Cl2 disinfection process led to changes in the water matrix, including organics, inorganics, bacteria, and components that provide environmental pressure for the biofilm. These changes ultimately influenced the properties of the biofilm EPS, which had a direct impact on biofilm DBP-FP.
摘要：
饮用水分配系统（DWDS）中与生物膜相关的消毒副产物（DBP）问题引起了广泛关注。这项研究旨在研究模拟连续流DWDS中生物膜起源的卤化DBP形成潜力（生物膜DBP-FP）的变化，这些DWDS经过不同UV剂量的顺序UV和氯消毒（UV-Cl2）处理，并提出了潜在的机制。三卤甲烷（THM）的形成潜力，卤代乙酸(HAAs),和总有机卤素(TOX，测定了由生物膜产生的X=Cl和Br)。结果表明，生物膜TOCl-FP在80mJ/cm2的UV剂量下处于最小值，对应于胞外聚合物（EPS）中蛋白质和多糖的最低量。鞘氨醇,甲基杆菌,鞘氨醇单胞菌在蛋白质和多糖的生物合成中起着至关重要的作用。细菌群落组成特征和代谢功能分析表明，由于UV-Cl2消毒，优势细菌发生变化，代谢功能发生了变化。随着紫外线剂量的增加，α变形杆菌的相对丰度增加，而细菌则显示出相反的趋势。相关分析表明,UV-Cl2消毒过程导致了水基质的变化,包括有机物,无机物,细菌,以及为生物膜提供环境压力的组件。这些变化最终影响了生物膜EPS的特性，对生物膜DBP-FP有直接影响。
