UV-氯消毒后供水管网生物膜的应激反应研究

Stress Response of Biofilm in Water Supply Network to Pre-disinfection of Sequential UV and Chlorine

为研究供水系统中紫外线与氯顺序消毒(UV-氯)后管网生物膜的应激反应,本文搭建消毒至供水管网的连续流实验装置,设置不同剂量的UV-氯消毒单元,探索和比较消毒后管网生物膜微生物活性、群落结构、胞外聚合物(extracellular polymeric substances,EPS)组成和代谢特征的变化。结果表明:UV-氯消毒较单独氯后生物膜微生物表现出明显的团聚现象。生物膜中微生物以γ-变形菌纲、α-变形菌纲和拟杆菌纲为主,余氯量对生物膜优势菌群的影响要高于紫外剂量带来的影响。EPS含量受到余氯及紫外剂量的共同作用,其中蛋白质比例高于多糖。代尔夫特菌属、寡养单胞菌属、鞘脂菌属、假单胞菌属和甲基杆菌属等是影响EPS合成的重要菌属。其中,假单胞菌属、甲基杆菌属、鞘氨醇单胞菌属具有耐氯性,假单胞菌属、代尔夫特菌属不耐紫外。该研究成果有助于了解管网中生物膜情况,并可为UV-氯消毒对饮用水微生物安全问题的影响提供一定参考。

This study sought to examine the change of biofilm in a simulated continuous-flow drinking water distribution system subjected to sequential UV and chlorine disinfection(UV-chlorine)treatments.The different doses of UV-chlorine disinfection were set up to compare the changes in microbial activity,community structure,extracellular polymeric substances(EPS),and metabolic characteristics of biofilm.In contrast to when chlorine disinfection was used,the bacteria in the biofilm following UV-chlorine disinfection displayed apparent aggregation.Gammaproteobacteria,Alphaproteobacteria,and Bacteroidia were the most prevalent bacteria in the biofilm,and residual chlorine had a more substantial impact on the dominant bacterial community than UV radiation.The amount of proteins was more than polysaccharides in EPS.The residual chlorine and UV dosage played an important role in the EPS content.Besides,the key bacterial genera Delftia,Stenotrophomonas,Sphingobium,Pseudomonas,and Methylobacterium had an impact on EPS production Pseudomonas,Methylobacterium,and Sphingobium had chlorine resistance,while Pseudomonas and Delftia were not UV resistant.Theoutcome of this study is bound to understand the biofilm in the pipeline and can provide references for studying the influence of UV-chlorine disinfection on the microbial safety of drinking water.