More effective removal of antibiotic resistance genes from excess sludge by microwave integrated fenton treatment

To reduce the risk of antibiotic resistance genes (ARGs) and class 1 integrons (intI1) in excess sludge, this study explored the effect of alkaline, microwave, fenton and the integrated treatments on ARGs removal. At the same time, the alteration of microbial community composition caused by different treatments was determined to explain the potential hosts of ARGs. By comparison, alkaline and microwave treatment increased the abundance of several ARGs and intI1, but fenton treatment largely reduced ARGs and intI1 abundance. Moreover, it was found that alkaline integrated fenton and microwave integrated fenton treatment strongly reduced target genes abundance, and the reduced amount was higher than fenton only. Additionally, the microbial community structure was slightly changed by alkaline and microwave treatment, but was remarkably altered by fenton treatment. After fenton treatment, the relative abundance of Firmicutes and Actinobacteria was obviously elevated, suggesting that Firmicutes and Actinobacteria might be the possible hosts for the remaining ARGs. It is expected that this study could provide crucial information for reducing the risk of ARGs from excess sludge entering in the environment. CK: sludge without any treatment; Single treatments: alkaline treatment for 10h (A-10h), microwave treatment for 180s (M-180s), fenton treatment for 2h (F-2h); Integrated treatments: A-10h integrated M-180s (AM), A-10h integrated F-2h (AF), M-180s integrated F-2h (MF). [Display omitted] •Alkaline and microwave treatment may enhance the risk of ARGs in excess sludge.•Fenton treatment may reduce the risk of ARGs in excess sludge.•Alkaline or microwave integrated fenton treatment could remove more ARGs.•Fenton treatment may be unable to remove ARGs hosting in Firmicutes and Actinobacteria.