Unveiling a potential disinfection process in ultraviolet treatment of bromine-containing water: inactivation of P. aeruginosa in a UV/NH2Br system

Abstract

Monobromamine (NH₂Br) is a weak oxidant generated in the chlorination process of bromine- and ammonia-containing water. Under advanced oxidation conditions like ultraviolet (UV) irradiation, the N–Br bond in NH₂Br can be cleaved to generate Br˙ and HO˙, which endows NH₂Br with remarkable disinfection potential. This study systematically assessed the effectiveness of the UV/NH₂Br system in the inactivation of P. aeruginosa (log reduction = 3.78), which showed significantly better performance than UV (log reduction = 1.32) and NH₂Br (log reduction = 0.48) alone. Next, we characterized specific substances in the water samples from multiple perspectives, including intracellular reactive oxygen species (ROS), as well as the efflux of ATP, DNA, and proteins, to elucidate the sterilization mechanism. Besides, the dark repair potential of bacteria and the removal efficiency of antibiotic resistance genes (ARGs) in the UV/NH₂Br system were investigated. Due to its efficient generation of free radicals, the UV/NH₂Br system also demonstrated effectiveness in depressing dark repair potential of bacteria and removing ARGs. Finally, the impact of factors, including pH, alkalinity and water matrix, on the sterilization efficacy of the UV/NH₂Br system was investigated. Our study unveils a potential disinfection mechanism in treating bromine-containing water using advanced oxidation processes. This finding contributes to a more comprehensive understanding of the UV disinfection mechanism in drinking water treatment processes.