Fate and removal of antibiotic resistance genes in heavy metals and dye co-contaminated wastewater treatment system amended with β-cyclodextrin functionalized biochar.

Biochar has been received increasing concerns regarding its environmental effect, which is promising in wastewater treatment. In this study, the performance of β-cyclodextrin functionalized biochar (β-BC) on the removal of antibiotic resistance genes (ARGs) in wastewater treatment under the co-stresses of heavy metals and dye is evaluated. Results show that when 20 mg/L heavy metals (HMs) and 150 mg/L methyl orange (MO) are present in daily fed influent, only 0.05 mg/L HMs residual and 96.79%–98.84% MO removal efficiency achieved in β-BC additive group, compare to 0.16 mg/L and 87.92%–94.11% of that in control, respectively, indicating that β-BC can benefits the performance of contaminants removal. To evaluate the role of β-BC plays on ARGs in multi-contaminants stressed system, tet W, tet M, sul-1, sul-2, blaTEM, oxa-1, qnr-S, erm-B and intI-1 are identified. The relative abundance of all identified ARGs are decreased when β-BC presence compared to the corresponding groups without β-BC additive. The diversity and composition of microbial community are explored and the reduction of potential antibiotic-resistant bacteria is speculated as a driver of ARGs removal. In conclusion, our study demonstrates that β-BC possesses the ability to promote the removal of ARGs during continuous wastewater treatment under HMs-MO co-contaminant.