Enhancing efficacy and microbial community dynamics in forward osmosis membrane bioreactors for treating micro-polluted surface water

A system known as the forward osmosis membrane bioreactor (FOMBR) was developed to treat micro-polluted surface water (MPSW) efficiently. Extensive investigations were conducted to assess the system's ability to remove pollutants, evaluate membrane fouling behaviour, and observe changes in the microbial community. The findings revealed remarkable removal rates for NH4+-N and TP, reaching 99.6 ± 0.3 % and 91.2 ± 6.4 %, resulting in effluent concentrations below 0.03 and 0.07 mg/L. Additionally, the average removal rates for turbidity, CODMn, UV254, and UV410 were found to be 99.3 ± 0.1 %, 81.7 ± 3.0 %, 93.1 ± 2.9 %, and 98.3 ± 1.9 %, respectively. Throughout the 30-day operation, a fouling layer consisting of loosely structured materials was observed solely at the periphery of the membrane module. Polysaccharides and proteins were identified as the primary organic pollutants within this fouling layer, while inorganic contaminants such as Si, Al, Cl, Fe, and Na were also detected. Microbial community analysis revealed that the nutrient-deficient conditions within the system influenced the structure of the microbial community and enhanced microbial diversity. Under nutrient-deficient conditions, the microbial community exhibited a remarkable tolerance to high salinity resulting from reverse diffusion caused by draw solutions. Consequently, the FOMBR system shows great potential as a viable option to treat micro-polluted surface water sources (MPSW).