氯和氯胺冲击消毒对二次供水管道生物膜的控制作用

针对建筑二次供水管壁生物膜对饮用水的生物安全性构成的潜在威胁，采用生物膜反应器(BAR)模拟二次供水管道，研究氯和氯胺冲击消毒过程对管壁生物膜的细菌总数、大肠杆菌和异养菌(HPC)灭活效果以及对生物膜结构的影响.结果表明，在第80天时生物膜中生物量达到最大，生物膜宏基因组分析表明，厚壁菌门(Firmicutes)、变形菌门(Proteobacteria)和拟杆菌(Bacteroidetes)为优势菌种.冲击消毒对生物膜的灭活效能与氯和氯胺的质量浓度以及CT值有关，在相同CT值条件下，高质量浓度氯和氯胺的灭活效果更佳.氯和氯胺的生物膜灭活效果对比可以看出，在低投量条件下，氯的细菌总数和大肠杆菌灭活效果好于氯胺，但氯的HPC灭活效果弱于氯胺；在高投量条件下，消毒剂质量浓度和CT值与生物膜的灭活效果无明显相关性，可以达到快速消毒的效果.在氯和氯胺的投加质量浓度为3.0 mg/L、CT值300~400 mg·min/L的最佳冲击消毒条件下，生物膜中细菌总数、大肠杆菌和HPC的灭活率均达到95%以上.从生物膜的表面特性分析可以看出，冲击消毒后生物膜结构破坏明显，生物膜变薄或脱落；氯冲击消毒对生物膜的破坏和削减程度优于氯胺，更有利于管道生物膜的控制
Focused on the potential threat of the membrane fouling to the bio-safety of the drinking water in the second water supply, this study investigated the effect of shock chlorine and chloramine disinfection on the total Bacteria, Escherichia Coli and Heterotrophic (HPC) bacteria as well as the structure of the biofilm in the BAR-simulated secondary water supply system. The results showed that the number of microbes in the biofilm reached maximum on the 80th day and soon it fluctuated smoothly. The Firmicutes, Proteobacteria and Bacteroidetes were predominant bacteria by Metagenomic approaches. The effect of chlorine and chloramine disinfection on the biofilm was related to the concentration of the disinfectant as well as the concentration and time(CT). At the same CT value, higher concentration of Chlorine and chloramine had more effective disinfection. Comparison and analysis found that in low concentrations, compared to chloramine, chlorine is more effective to total Bacteria and Escherichia Coli, while less effective to HPC. However, in high concentrations, chlorine and chloramine own nearly the same inactivated effect. When the concentration of chlorine and chloramine was 3.0 mg/L and the CT value was 300-400 mg·min/L, the inactivation rate of total Bacteria, Escherichia Coli and HPC was as high as 95%. Scanning Electron Microscope(SEM) images of biofilm surface plot analysis illustrated that the structure of biofilm was damaged seriously, and shock chlorine disinfection, compared to chloramine, possessed less impact to the structure and reduction degree of the biofilm and was hence more conducive to the biofilm control