氯/二氧化氯消毒对热水管壁生物膜的控制作用

Effects of disinfection by chlorine and chlorine dioxide on pipeline biofilm in hot water supply system

摘要:

建筑生活热水存在严重的生物安全性问题,需要采取必要的消毒措施.为此,采用建筑生活热水模拟管道系统,对比研究氯或二氧化氯冲击消毒对管壁生物膜微生物的灭活效果,并通过高通量测序和扫描电子显微镜评估冲击消毒对管壁生物膜群落组成和生物膜表观特征的影响.结果表明,高消毒剂质量浓度可显著提高微生物的灭活速率,但已不能进一步改善微生物灭活率；1.5 mg/L氯或二氧化氯的消毒效果不佳；3～5 mg/L氯或二氧化氯在冲击消毒120 min后,总大肠菌群、细菌总数和异养菌(HPC)均可达到完全灭活的程度,能够有效控制热水管道生物膜,说明足够的消毒剂质量浓度和消毒时间对保持高效灭活率非常必要.生活热水管壁生物膜的微生物多样性丰富,异常球菌-栖热菌门和变形菌门为优势门,并含有多种致病菌,与市政供水和二次供水管道系统的优势菌群有很大差异；氯或二氧化氯冲击消毒对各种菌门均有不同程度的灭活效果,二氧化氯对致病菌、变形菌门和衣原体门等的灭活效果更佳.氯或二氧化氯冲击消毒能有效破坏生物膜的表面结构,使生物膜出现间隙变大、萎缩、脱落等现象,二氧化氯对生物膜的破坏作用更显著,具有更佳的冲击消毒作用和消毒效果.研究结果为建筑生活热水系统的安全消毒技术以及生物安全性保障提供了支持.

Abstract:

Effective disinfection measures are in urgent need due to the serious biosafety issues in domestic hot water supply system. In this study, biofilms annular reactor was applied to simulate the domestic hot water pipeline system. The effects of chlorine and chlorine dioxide on microbial inactivation in biofilm were investigated. The changes of microbial community and the surface structure of biofilm were further explored using Illumina MiSeq sequencing and scanning electron microscopy (SEM). The results show that by increasing disinfectant concentration, the microbial inactivation rate could be notably improved while the inactivation effect remained stable. 1.5 mg/L chlorine or chlorine dioxide did not achieve a good microbial inactivation effect. However, the complete inactivation of Escherichia coli, total number of bacteria and heterotrophic bacteria (HPC) were observed in the presence of 3-5 mg/L chlorine and chlorine dioxide. 3-5 mg/L chlorine and chlorine dioxide can effectively control the biofilm of hot water pipeline. The results suggest that adequate concentration of disinfectant and disinfection time are important for keeping high inactivation effect. The pipeline biofilm was high in bio-diversity. Different from those in municipal water supply system and the secondary water supply system, the predominant phyla of pipeline biofilm were Deinococcus-Thermus and Proteobacteria, as well as some detected pathogenic bacteria. The shock disinfection of chlorine or chlorine dioxide showed a different inactivation effect on each phylum. Specifically, compared with chlorine, chlorine dioxide had a better inactivation effect on pathogenic bacteria, Proteobacteria, and Chlamydiae. The results of SEM indicate that the surface structure of biofilm was effectively destroyed by chlorine and chlorine dioxide, resulting in the larger gaps, shrinkage, and shedding of biofilm. Moreover, the effect of chlorine dioxide on biofilm surface structure was higher than chlorine. Overall, the results are important for the biosafety in hot water system.