Removal of antibiotic resistance genes from post-treated swine wastewater by mFe/nCu system

In this study, a distinct type of nanoscale copper, produced by iron-copper replacement (mFe/nCu), was used to reduce ARGs from post-treated swine wastewater. The effects of several key parameters (i. e., theoretical Cu mass loadings, mFe/nCu dosage, air flow rate, initial pH and temperature) were investigated in details. The contribution of nanoscale copper in mFe/nCu system towards ARGs removal was determined. Furthermore, the removal mechanism of ARGs by mFe/nCu was examined by SEM, TEM and living/dead cell staining. Results indicate that the mFe/nCu process can promptly remove the absolute abundances of ARGs (˃2.4 logs) from post-treated swine wastewater. The outstanding performance of this approach could be attributed to the use of nanoscale copper itself rather than the oxidation by Fenton-like reaction of mFe/nCu bimetallic system. Moreover, the mFe/nCu process exhibited an excellent activity in regards bacterial killing and destruction of ARGs structure and function which, ultimately, could serve as a plausible mechanism of ARGs removal. Reactivation experiments showed that ARGs removal by mFe/nCu was permanent and irreversible. Altogether, our findings suggest that mFe/nCu treatment can be a promising advanced method for ARGs removal from post-treated swine wastewater.