Environmental Simulation and Pollution Control State Key Joint Laboratory, State Environmental Protection Key Laboratory of Microorganism Application and Risk Control (SMARC), School of Environment, Tsinghua University, Beijing 100084, PR China.
Environmental Simulation and Pollution Control State Key Joint Laboratory, State Environmental Protection Key Laboratory of Microorganism Application and Risk Control (SMARC), School of Environment, Tsinghua University, Beijing 100084, PR China.
Sci Total Environ. 2019 Nov 25;693:133579. doi: 10.1016/j.scitotenv.2019.133579. Epub 2019 Jul 24.
Biofouling of reverse osmosis (RO) membranes is an inevitable issue in wastewater reclamation and limits the application of RO systems. Chlorine disinfection is widely used as a pretreatment to control biofouling. However, the extracellular polymeric substances (EPS) and cellular inclusions released during chlorine disinfection might also cause membrane fouling. Furthermore, little is known regarding the chlorine resistance of bacterial strains found on fouled RO membranes. In this study, four bacterial strains isolated from fouled RO membranes were used as testing subjects to investigate the bacterial inactivation performance of chlorine disinfection. The effects of chlorine disinfection on the RO membrane fouling potential of these strains were also revealed. The chlorine resistance ability of Sphingopyxis sp. BM1-1 was strongest among the four strains as it secretes the highest amount of EPS per cell. The log inactivation efficiency of this strain was 1-log by 0.2 mg-Cl/L in 30 min, which was one to three orders of magnitude lower than that of the other strains. Although chlorine disinfection inactivated most bacterial cells (>90%), the reaction with chlorine significantly increased the RO membrane fouling potential of all bacterial solutions. To elucidate the main mechanism behind the increase in the fouling potential, we further investigated the changes in the properties of EPS, and the release of EPS and cellular inclusions during chlorine disinfection. Chlorine disinfection did not significantly affect the RO membrane fouling potential of the EPS secreted by these bacterial strains. However, dissolved organic carbon (DOC), protein, polysaccharide, and DNA concentration of all bacterial solutions increased by one to nine times after chlorine disinfection. These results indicate that large amounts of EPS and cellular inclusions were released into the solutions after the reaction with chlorine, which was the main cause of the increase in RO membrane fouling potential of the bacterial solution after chlorine disinfection.
反渗透（RO）膜的生物污染是废水回用中不可避免的问题，限制了 RO 系统的应用。氯消毒广泛用作控制生物污染的预处理方法。然而，在氯消毒过程中释放的细胞外聚合物（EPS）和细胞内含物也可能导致膜污染。此外，对于在污染的 RO 膜上发现的细菌菌株的氯抗性知之甚少。在这项研究中，从污染的 RO 膜中分离出的四种细菌菌株被用作测试对象，以研究氯消毒对这些菌株的细菌灭活性能。还揭示了氯消毒对这些菌株的 RO 膜污染潜力的影响。四种菌株中，Sphingopyxis sp. BM1-1 的氯抗性能力最强，因为它每细胞分泌的 EPS 量最高。该菌株的对数灭活效率在 30 分钟内通过 0.2 mg-Cl/L 达到 1-log，比其他菌株低一到三个数量级。尽管氯消毒使大多数细菌细胞失活（>90%），但与氯的反应显著增加了所有细菌溶液的 RO 膜污染潜力。为了阐明污染潜力增加的主要机制，我们进一步研究了 EPS 特性的变化，以及在氯消毒过程中 EPS 和细胞内含物的释放。氯消毒对这些细菌菌株分泌的 EPS 的 RO 膜污染潜力没有显著影响。然而，所有细菌溶液的溶解有机碳（DOC）、蛋白质、多糖和 DNA 浓度在氯消毒后增加了一到九倍。这些结果表明，大量的 EPS 和细胞内含物在与氯反应后释放到溶液中，这是氯消毒后细菌溶液的 RO 膜污染潜力增加的主要原因。
