紫外线消毒对再生水中微生物生长分泌特性的影响

EFFECT OF ULTRAVIOLET DISINFECTION ON GROWTH AND SECRETION CHARACTERISTICS OF MICROORGANISM IN RECLAIMED WATER

膜污堵是阻碍污水再生处理反渗透(RO)系统稳定、高效运行的突出问题。前期研究表明,RO系统常用的氯消毒预处理会导致微生物群落结构及代谢产物分泌特性发生显著改变,从而引起严重的生物污堵。为优化污水再生处理RO系统的预处理工艺选择,该研究全面考察了紫外线消毒对再生水中细菌的生长、群落结构和分泌特性的影响。结果表明:紫外线剂量为20,40,80 mJ/cm^2时,对膜生物反应器出水中细菌的灭活率分别可达1log、3log、4log。紫外消毒后,存活细菌再培养时其生长迟滞期变长,稳定期细菌数量在紫外线剂量为40,80 mJ/cm^2时分别比对照组降低18.6%和19.2%。高紫外线剂量下(40,80 mJ/cm^2),变形菌门、β-变形菌纲、詹森菌属相对丰度有所增加。分泌特性方面,细菌胞外多聚物含量随紫外线剂量升高先减少后增多,且其中大分子物质增多,并表现出更强的RO膜污堵潜势。

Membrane fouling is a prominent problem that hinders the stable and efficient operation of reverse osmosis(RO)system for wastewater reclamation.Previous studies showed that chlorine disinfection,which was commonly used in RO system as the pretreatment could lead to significant change in microbial community structure and secretion characteristics,resulting in serious biofouling.In order to optimize the selection of pretreatment process for RO system in wastewater reclamation,the effect of ultraviolet(UV)disinfection on the growth,community structure and secretion characteristics of microorganism in reclaimed water was investigated.Results showed that when the UV dose was 20,40 and 80 mJ/cm^2,the inactivation rate of bacteria reached 1,3 and 4 log,respectively.The lag period of bacterial growth was prolonged after UV disinfection.The biomass in stable period also decreased by 18.6% and 19.2% compared with the control group,when the UV dose was 40 and 80 mJ/cm^2.The relative abundance of Proteobacteria phylum,Betaproteobacteria class and Janthinobacterium genus increased at higher UV dose(40,80 mJ/cm^2).In terms of secretion characteristics,the amount of extracellular polymeric substances(EPS)decreased firstly and then increased with the increase of UV dose,and the content of macromolecule substances in them increased after UV disinfection,showing higher potential of RO membrane fouling.