Monitoring and assessing different strategies of wastewater treatment plants on dissemination of antibiotic resistance in the downstream river environment

Nowadays, wastewater discharge is a significant challenge, particularly in developing countries. This study aimed to evaluate the treatment strategies of wastewater treatment plants (WWTPs) and their role in disseminating antibiotic-resistant E. coli in the downstream Ganges River. The removal efficiencies and reduction of antibiotic-resistant E. coli were examined in each treatment step. Physicochemical analysis revealed that removal efficiencies of parameters such as TDS, BOD, and COD were highest by MBBR (moving bed biofilm reactor)-based WWTP, and lowest by UASB (upflow anaerobic sludge blanket)-based WWTP. The E. coli isolates showed maximum resistance against vancomycin, erythromycin, doxycycline, and ampicillin antibiotics. The Ganges River water samples were also highly abundant with antibiotic-resistant E. coli, suggesting that while WWTPs contribute to the microbial load, greater contamination observed in the Ganges River likely results from additional point and non-point sources, including untreated discharges, which may surpass the impact of treated WWTP effluent. This study highlights the presence of antibiotic-resistant bacteria (ARB) across different treatment stages in WWTPs and indicates the potential for treated effluents to contribute to downstream ARB loads. This is an alarming issue that requires stringent surveillance and minor improvements in existing treatment technologies to prevent the dissemination of antibiotic resistance.