Prevalence of antibiotic resistant genes in selected activated sludge processes in Isfahan Province, Iran

Wastewater treatment plants are one of the main sources of dissemination of antibiotic resistance genes (ARGs) into the environment. The present study was conducted to determine the prevalence and removal of ARGs in different wastewater treatment processes. A total of 36 samples from raw and final effluent of different activated sludge processes were collected and analyzed. Molecular analysis was conducted on the samples for the detection of encoding genes resistant to three groups of antibiotics (tetracycline, erythromycin, and sulfonamide). The results of this study showed that all ARGs were identified in activated sludge processes (average 70%). Comparison of different activated sludge processed showed that the removal percentage patterns were A-B process, conventional process, and extended aeration process, respectively. The results of this study showed that ARGs were present in relatively high levels in activated sludge process. The results also indicated that the activated sludge process did not contribute to effective reduction of ARGs. However, this revealed the major role of the activated sludge process in the distribution of ARGs in the environment. Thus, it seems that the improvement of the process is necessary for ARGs control in activated sludge process.