Antibiotic resistant bacteria inactivation through metal-free electrochemical disinfection with carbon catalysts and its potential risks

Recently, increasing attention has been paid to the inactivation of antibiotic resistant bacteria (ARB) during the electrochemical disinfection. However, no available information could be found on ARB inactivation in water during metal-free electrochemical disinfection. In this study, polyvinylidene fluoride (PVDF)-based carbon catalyst (PPC) was chosen as working electrode. Batch experiments were conducted to investigate key design for ARB inactivation, effects of water matrix and potential risks after the disinfection under the pre-determined conditions. The disinfection with current density at 2.25 mA/cm(2) and Air/Water ratio of 10:1 was optimal with the largest ARB inactivation (5.0 log reduction for 40 min), which was in line with the profile and yield of hydrogen peroxide (H2O2) during the disinfection. Effects of water matrix analysis implied that ARB inactivation efficiencies during the disinfection in acidic solutions were better than the one in alkaline solutions, which could be due to rich C=C levels on surface of PPC cathode. After the optimal disinfection, ARB counts increased slightly at the first 2 h and then tended to disappear, and there were no conjugation transfer and little transformation for target antibiotic resistance genes, indicating that potential risks could be blocked after the disinfection for 40 min. Furthermore, intermittent flow was more effective in inactivating ARB compared with continuous flow. These suggested that the application of metal-free electrochemical disinfection with PPC to inactivate ARB in water was feasible and desirable in this study.