Synergistic UVA-Cu2+ disinfection in water environments: simultaneous removal of pathogens, antibiotics and antibiotic resistance genes

Abstract The World Health Organization recognizes antimicrobial resistance as a serious threat to human health. The water environments play an important role as a habitat for bacteria and are conducive to the transfer of antimicrobial resistance genes (ARGs). Although various methods for water disinfection have been developed, further efforts are still necessary to balance efficiency, cost, and safety. The work shows that the combination of ultraviolet A (UVA) and copper ions (Cu 2+ ) synergistically inactivates pathogens, including Escherichia coli , Aeromonas hydrophila , Vibrio parahaemolyticus , and Staphylococcus aureus . Exposure to UVA for 3 h in the presence of 50 μM Cu 2+ resulted in an 8 log 10 CFU/mL reduction in viable bacteria. Moreover, the UVA–Cu 2+ system effectively degraded residual antibiotics, achieving removal efficiencies of 99.55% for sulfamethoxazole and 74.04% for enrofloxacin under the same conditions. ARGs, including bla TEM-1 , tet (C), tet (A), and sul 2, were reduced to below the detection limit, thereby mitigating the risks posed by antibiotic residues and ARGs. Mechanistic studies revealed that the UVA–Cu 2+ treatment triggers excessive reactive oxygen species within bacteria, leading to DNA damage, protein carbonylation, lipid peroxidation and other oxidative damages, and even causing cell death. In summary, the UVA–Cu 2+ treatment can synergistically eradicate multidrug-resistant pathogens, antibiotic residues, and ARGs in a simultaneous manner. This research provides a feasible method for water environments disinfection and lays the foundation for future evaluation in complex wastewater matrices, while optimization of copper ions recovery would further enhance its environmental sustainability.