Enhanced inactivation of antibiotic-resistant bacteria isolated from secondary effluents by g-C3N4 photocatalysis

Ding, Ning; Chang, Xueming; Shi, Na; Yin, Xiufeng; Qi, Fei; Sun, Yingxue

Enhanced inactivation of antibiotic-resistant bacteria isolated from secondary effluents by g-C3N4 photocatalysis

2019

The extensive use of antibiotics has resulted in the development of antibiotic-resistant bacteria (ARB), which may not be completely removed by traditional wastewater treatment processes. More effective approaches to disinfection are needed to prevent the release of ARB into the surface water. The metal-free photocatalyst graphitic carbon nitride (g-C₃N₄) has aroused great interest as a possible agent for water and wastewater treatment, due to its low cytotoxicity and photoactivity with visible light. In this study, the efficacy of g-C₃N₄ was assessed as a possible means to enhance ARB inactivation by irradiation. ARB were isolated and purified from secondary effluents in 4 municipal wastewater treatment plants. Of these, 4 typical multi-drug ARB isolates, belonging to Enterobacteriaceae, were selected for irradiation experiments. Inactivation was seen to increase with irradiation time. At 60 min, the inactivation of the 4 ARB isolates by light at > 300 nm and > 400 nm was in the range of 0.25–0.39 log and 0.16–0.19 log, respectively. The use of g-C₃N₄-mediated photocatalysis at the same wavelengths significantly enhanced that to 0.64–1.26 log and 0.31–0.41 log, respectively. The antibiotic susceptibility of the ARB isolates remained unchanged either prior to or after irradiation and was independent of photon fluence, reaction time, and the presence of g-C₃N₄. This study establishes a baseline for understanding the effectiveness of g-C₃N₄ photocatalysis on inactivation of ARB in wastewaters and lays the foundation for further improvement in the use of photocatalysis for wastewater treatment.

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