Occurrence and degradation of emerging antibiotic-resistant bacteria in riverine environment with sono, photo, and sonophotocatalytic oxidation under low-frequency ultrasound and sunlight.

The current study reports the prevalence of antibiotic-resistant bacteria, Escherichia coli (E. coli) in riverine environments and their removal using advanced oxidation processes such as sonocatalysis (ultrasound), photocatalysis (sunlight), and sonophotocatalysis (ultrasound/sunlight) techniques utilizing zinc oxide (ZnO) as the catalyst. Results showed that about 96% of the E. coli isolates exhibited resistance to at least one tested antibiotic, and 47% were identified as multi-drug resistant (MDR). An MDR E. coli strain isolated from the Periyar River was selected as the target for the studies. Survey study conducted revealed that 12% of the participants reported the use of ampicillin, with 75% of the isolates displaying resistance to this antibiotic. Moreover, sonophotocatalysis system demonstrated the highest efficiency achieving approximately 90% degradation of AR E. coli within 90 min. No re-emergence of antibiotic-resistant bacteria (ARB) was observed in the presence of ZnO. Sonophotocatalytic system was further validated in real water matrices, and results indicated that the efficiency of bacterial removal varied depending on the contamination levels of each water source, following the order: groundwater > river water > lake water > wastewater. The findings underscore the emergence of antibiotic resistance in aquatic bacteria that are typically exposed to antibiotics. This is the first study to demonstrate the feasibility of using inexpensive and renewable solar energy in combination with ultrasound for the purification of ARB-contaminated wastewater, thereby preventing the transmission of ARB and addressing the One Health challenges associated with them.