Membrane fouling mechanism of chlorine-resistant bacteria (CRB) in a seawater desalination reverse osmosis (SWRO) system

Abstract

Biofouling affects over 45% of seawater desalination reverse osmosis (SWRO) membrane systems, impeding the advancement of this technology. Notably, there is a positive correlation between membrane fouling potential and resistance to chlorine. Therefore, understanding the fouling mechanism of chlorine-resistant bacteria (CRB) provides a new perspective for controlling bacterial biofouling in SWRO systems. In this study, ten CRB were isolated from biofouled SWRO membranes at a nuclear power plant in China. All these bacteria demonstrated strong capacity for biofilm formation, characterized by the presence of high-molecular-weight exopolysaccharides, with protein content exceeding that of polysaccharides in the biofilm matrix. The primary monosaccharides in these exopolysaccharides were glucose and mannose, which enhanced the integrity of the extracellular polymeric substances (EPS) and contributed to the formation of robust, viscous biofilms. Infrared (IR) spectroscopy confirmed the presence of α-1,4 glycosidic linkages and amide II bonds, which are associated with biofouling in the EPS. The findings provide insights into the control of membrane biofouling in SWRO systems.