Removal of Intracellular and Extracellular Antibiotic Resistance Genes in Municipal Wastewater Effluent by Electrocoagulation

Abstract

Effluent from wastewater treatment plants (WWTPs) is considered to be an important source of antibiotic resistance genes (ARGs) in the environment, which has become a global issue for human and animal health. However, the conventional treatment processes in WWTPs including the disinfection process cannot remove ARGs completely. This study estimated the removal efficiency of selected ARGs (sul1, sul2, tetO, and tetX) from WWTP effluent by electrocoagulation (EC). A reduction of 1.48-2.61 logs for selected ARGs was obtained by EC with the electrolysis time of 60 min under a current density of 20.0 mA/cm2 at neutral pH. Adsorption and enmeshment of the precipitated flocs generated electrochemically were proposed as the main mechanism for the removal of ARGs by EC. High current density and low pH (3.0-7.0) could promote the removal of ARGs. When pretreated with conventional ultraviolet (UV) disinfection, the reduction logs of ARGs were higher than the sum of that by single UV disinfection and EC process, ranging from 1.62 to 2.83 logs after 30 min of electrolysis. Moreover, it was found that the abundance of extracellular ARGs was increased after UV disinfection but reduced significantly after the subsequent EC treatment. The results showed that EC would be an effective method for the removal of both intracellular and extracellular ARGs from WWTPs effluent.