Enhanced filtration performance of biocarriers facilitated gravity-driven membrane (GDM) by vacuum ultraviolet (VUV) pretreatment: Membrane biofouling characteristics and bacterial investigation

Membrane biofouling is a challenge for biocarriers facilitated gravity-driven membrane (GDM) systems to achieve high-efficiency filtration in decentralized drinking water treatment. The purpose of this study was to investigate the effects of vacuum ultraviolet (VUV) as a pretreatment on membrane fouling, permeate water quality and bacterial communities. VUV pretreatment was found to significantly reduce the cake layer resistance by 24.4% and the membrane pore resistance by 40.0% (p < 0.05), resulting in a 22.2% increase in stable flux. The removal of low molecular weight neutrals and protein-like materials was enhanced by 22.5% and 40.1% respectively after VUV pretreatment. The heterogeneity of the biofouling layer was improved by VUV pretreatment, and the porosity and roughness were increased by 227.5% and 46.5%, respectively. The application of VUV pretreatment resulted in a larger nanoparticle size in the biofouling layer suspension (peak at 85.4 nm), improvement in the membrane hydrophilicity, and a decrease in protein-like substances adhesion. The richness and diversity of the bacterial community were decreased by VUV pretreatment. The bacterial community structure had the highest mantel correlation with biopolymers (r = 0.89). Overall, VUV pretreatment can be a promising strategy to effectively alleviate membrane biofouling in biocarriers facilitated GDM systems.