Microplastics in anoxic/aerobic membrane bioreactor (A/O-MBR): Characteristics, biofilms, degradation and carrier for antibiotic resistance genes

Abstract

Wastewater treatment plants (WWTPs) are proposed as one of the ways for microplastics (MPs) to enter the water environment. MPs as the carrier of other pollutants, the inevitable aging process will change the characteristics and fate of MPs. Herein, the physicochemical property alteration, microbial community evolution and antibiotic resistance genes (ARGs) occurrence of the aged MPs surface were analyzed in A/O-MBR system. Remarkable alteration in MPs surface properties, which included the decrease in hydrophobicity and the increase in oxygen-containing functional groups, led to aging of MPs. Aging MPs are more likely to grow biofilms, which further increased the probability of microbial colonization. The genera Hydrogenophaga, Exiguobacterium, Enterobacter, Vibrio, Flavobacterium and Bacillus on MPs surface showed higher degradation potential. ARGs determination results indicated that MPs could enrich ARGs on their surface, and the relative abundance of β-lactam ARGs on different MPs surfaces was the highest. The above research results indicated that MPs in sewage treatment systems not only undergo aging, but also carry ARGs, causing further harm to the environment.