Fate of Antibiotic Resistance Genes During Sludge Anaerobic Fermentation: Roles of Different Sludge Pretreatment

Abstract

Excess sludge, the primary by-product of wastewater treatment plants, is the source and sink of antibiotic resistance genes (ARGs). This study established seven anaerobic digesters to investigate the fate of typical ARGs with different sludge pretreatments. It was found anaerobic digestion could effectively remove ARGs, and the reduce efficiency of ARGs was the highest in 50 °C pretreatment, following by oxidant addition. Microbial community analysis demonstrated ARGs hosts were significantly changed and influenced by high temperature. In addition, high temperature and K2S2O8 observably decrease the level of ROS production. Macro transcriptome analysis indicated that sludge pretreatment, except for 50 ℃ pretreatment, up-regulated the genes relevant to lyases and transferase, but down-regulated the genes responsible for peroxidase, antioxidant enzymes and T4SS gene. This study emphasized and compared the different sludge pretreatments on the fate of ARGs in anaerobic sludge, and highlighted concerns regarding the environmental and health risks to our society.

Keywords: Anaerobic fermentation, Waste activated sludge, Antibiotic resistance genes, Reactive oxygen species, Microbial community