Wu Yin-Hu, Chen Zhuo, Li Xu, Wang Yun-Hong, Liu Bo, Chen Gen-Qiang, Luo Li-Wei, Wang Hao-Bin, Tong Xin, Bai Yuan, Xu Yu-Qing, Ikuno Nozomu, Li Cai-Feng, Zhang Hong-Yu, Hu Hong-Ying
School of Environment, Tsinghua University, Environmental Simulation and Pollution Control State Key Joint Laboratory, Beijing 100084, PR China; Beijing Laboratory for Environmental Frontier Technologies, Beijing 100084, PR China.
School of Environment, Tsinghua University, Environmental Simulation and Pollution Control State Key Joint Laboratory, Beijing 100084, PR China; Beijing Laboratory for Environmental Frontier Technologies, Beijing 100084, PR China.
Water Res. 2021 May 1;195:116995. doi: 10.1016/j.watres.2021.116995. Epub 2021 Mar 2.
Membrane fouling is a prominent problem that hinders the stable and efficient operation of the reverse osmosis (RO) system for wastewater reclamation. Previous studies showed that chlorine disinfection, which was commonly used in industrial RO systems as pretreatment, could lead to significant change in microbial community structure and resulted in serious biofouling. In order to prevent biofouling during wastewater reclamation, the effect of ultraviolet (UV) disinfection on RO membrane fouling was investigated and the mechanism was also revealed in this study. With the disinfection pretreatment by UV of 20, 40 and 80 mJ/cm, the bacteria in the feed water were inactivated significantly with a log reduction of 1.11, 2.55 and 3.61-log, respectively. However, RO membrane fouling aggravated with higher UV dosage. Especially, in the group with the UV dosage of 80 mJ/cm, the normalized RO membrane flux decreased by 15% compared with the control group after 19-day operation. The morphology of the fouled RO membranes indicated serious biofouling in all groups. The analysis on the microbial amount of the foulants showed that the heterotrophic plate counts (HPC) and ATP content on the fouled RO membranes with and without UV disinfection were at the same level. However, the total organic carbon content of the foulants with the UV dosage of 40 and 80 mJ/cm was significantly higher than the control group, with higher content of proteins and polysaccharides as indicated by EEM and FTIR spectrum. Microbial community structure analysis showed that some typical UV-resistant bacteria were selected and remained on the RO membrane after disinfection with high UV dosage, including. These residual bacteria after disinfection with high UV dosage showed higher extracellular polymeric substances (EPS) secretion compared with those without UV disinfection, and thus aggravated RO membrane fouling. Thicker EPS could decrease the transmission of UV rays, and thus bacteria with higher EPS secretion might be selected after UV disinfection.
膜污染是阻碍反渗透（RO）系统稳定高效运行以实现废水回收利用的一个突出问题。先前的研究表明，工业RO系统中常用作预处理的氯消毒会导致微生物群落结构发生显著变化，并引发严重的生物污染。为了防止废水回收过程中的生物污染，本研究考察了紫外线（UV）消毒对RO膜污染的影响，并揭示了其作用机制。经20、40和80 mJ/cm的UV消毒预处理后，进水中的细菌被显著灭活，对数减少量分别为1.11、2.55和3.61对数。然而，较高的UV剂量会加剧RO膜污染。特别是，在UV剂量为80 mJ/cm的组中，运行19天后，归一化RO膜通量与对照组相比下降了15%。污染的RO膜的形态表明所有组均存在严重的生物污染。对污垢中微生物数量的分析表明，经过和未经过UV消毒的污染RO膜上的异养平板计数（HPC）和ATP含量处于同一水平。然而，UV剂量为40和80 mJ/cm的污垢中的总有机碳含量显著高于对照组，EEM和FTIR光谱表明蛋白质和多糖含量更高。微生物群落结构分析表明，在高剂量UV消毒后，一些典型的抗UV细菌被筛选出来并残留在RO膜上，包括……与未经过UV消毒的细菌相比，高剂量UV消毒后残留的这些细菌表现出更高的胞外聚合物（EPS）分泌，从而加剧了RO膜污染。较厚的EPS会降低UV射线的透射率，因此在UV消毒后可能会筛选出EPS分泌较高的细菌。
