Insight into the role of biogenic manganese oxides-assisted gravity-driven membrane filtration systems toward emerging contaminants removal

Abstract

Effective water purification technologies are required to remove emerging contaminants (ECs) and prevent their extensive occurrence in rural areas. In this work, coupling gravity-driven membrane (GDM) filtration with biogenic manganese oxides (BioMnOx) in the biofouling layer was utilized for treating water containing SMX. Comparisons between BioMnOx-GDM (with BioMnOx) and Control-GDM (without BioMnOx) indicated that BioMnOx could significantly promote the removal of DOC, NH₄⁺-N, and fluorescent pollutants due to its strong oxidating capacity and high biological activity. The formation of BioMnOx increased the abundance of SMX-degrading bacteria, enriched the metabolic pathway and mineralization rate of SMX, and effectively promoted the remove of SMX. More importantly, BioMnOx facilitated the removal of antibiotic resistance genes (ARGs) in the GDM, because it increased the link between microorganisms and reduced the concentration of SMX, thus reduced the expression of ARGs. LB-EPS played an important role in the membrane fouling. Compared with the Control-GDM, the concentration of LB-EPS in BioMnOx-GDM decreased, which was beneficial to alleviate membrane fouling. Although a thicker biofouling layer (1774.88 μm vs.775.54 μm) was formed in BioMnOx-GDM, the biofilm with higher porosity (64.93% vs. 41.24%) had a more positive effect on the flux. Overall, BioMnOx could improve the pollutant removal and stable flux level of the GDM system. BioMnOx-GDM effectively avoided the risks brought by ECs and ensured water safety in rural areas.

Keywords: Antibiotic resistance genes (ARGs); Biofouling layer; Biogenic manganes oxides (BioMnOx); Emerging contaminants (ECs); Gravity-driven membrane (GDM).