Chlorine disinfection significantly aggravated the biofouling of reverse osmosis membrane used for municipal wastewater reclamation. (1st May 2019)

• Record Type: Journal Article
• Authors: Wang, Yun-Hong; Wu, Yin-Hu; Tong, Xin; Yu, Tong; Peng, Lu; Bai, Yuan; Zhao, Xue-Hao; Huo, Zheng-Yang; Ikuno, Nozomu; Hu, Hong-Ying
• Is Part Of: Water research. Volume 154(2019)
• Page Start: 246
• Page End: 257
• Publication Date: 2019-05-01
• Subjects: Reverse osmosis -- Biofouling potential -- Membrane fouling -- Chlorine disinfection -- Reclaimed water -- Microbial community structure; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2019.02.008
• Languages: English
• ISSNs: 0043-1354

Abstract

Abstract: In reverse osmosis (RO) system for wastewater reclamation, biofouling is an inevitable issue. Chlorine disinfection is commonly used in pretreatment to control biofouling. Some chlorine-resistant bacteria could survive after chlorine disinfection and the microbial community structure in feed water changes significantly, thus leading to the change of biofouling potential. In this study, the effect of chlorine disinfection on the biofouling of RO membrane was investigated using a laboratory cross-flow RO system. Chlorine disinfection inactivated most bacteria in feed water. However, during the operation of RO system, with the increase of chlorine dosage the flux decline became more severe after a period of operation. The final normalized flux after 21 days was 0.27, 0.26, 0.20, and 0.21 with 0, 1, 5, and 15 mg-Cl2 /L chlorine as pretreatment, respectively. After the operation, the numbers of active bacteria in the foulants on the fouled membrane were on the same level regardless of the chlorine dosage, whereas the thickness of the foulants increased with the chlorine dosage significantly. Additionally, the higher total organic carbon concentration indicated more extracellular polymeric substances (EPS) in foulants. Microbial community structure analysis showed that the abundance and the species number of chlorine-resistant bacteria increased significantly with the chlorine dosage. Typical chlorine-resistant bacteria, including Methylobacterium, Pseudomonas, Sphingomonas, and Acinetobacter, were identified as significantly distinctive genera in the foulants after the pretreatment by 15 mg-Cl2 /L chlorine. Compared with the bacteria without chlorine disinfection, these remaining bacteria produced more EPS with higher molecular weight, which could be the major contribution to more severe RO membrane fouling after chlorine disinfection. Graphical abstract: Image 1 Highlights: Studied effect of chlorine disinfection on biofouling of reverse osmosis (RO) system. Applied lab RO systems, multiple microscopy, gene sequencing and organic analysis. Chlorine disinfection changed the microbial community structure in foulants. Four dominant chlorine-resistant strains were found in foulants with 15 mg-Cl2 /L. Extracellular polymeric substance produced by these strains caused severe biofouling.