Effect of modified microbial flocculant on membrane fouling alleviation in a hybrid aerobic granular sludge membrane system for wastewater reuse

Pre-coagulation is an excellent method for alleviating membrane fouling in aerobic granular sludge (AGS) membrane systems (AGSMSs) for wastewater reuse. However, little attention has been paid to modified microbial flocculants (MMFs) for membrane fouling mitigation. Herein, an MMF was prepared, and the effect of its dosage (5–30 mg/L) on membrane fouling mitigation was investigated. MMF pre-coagulation could effectively alleviate membrane fouling by utilizing electrical neutralization and adsorption bridging. When the MMF dosage was 10 mg/L, the membrane flux was increased by 79.4% and the total fouling resistance was reduced by 90.3%. The MMF dosage of 10 mg/L greatly inhibited the adhesion and accumulation of foulants, thereby forming a loose and porous cake layer on the membrane surface. Moreover, the extended Derjaguin–Landau–Verwey–Overbeek theory further clarified that the greatest energy barriers existed throughout the filtration process with an MMF dosage of 10 mg/L. Correlation analysis showed that the occurrence of membrane fouling was mainly related to total phosphorus, chemical oxygen demand, and polysaccharides in the raw wastewater. This study reveals the effects of different MMF dosages on membrane fouling and provides a novel approach for MMF pre-coagulation to mitigate membrane fouling.