Solar-driven butanedione-based disinfection: A by-product-free approach to pathogen control

• BD/Solar system effectively inactivated bacteria in a range of waters. • Acetyl peroxyl radicals contributed to bacteria inactivation in BD/Solar system. • BD/Solar inactivated bacteria via physiological and metabolic changes. • Disinfection with BD/Solar did not generate halogenated disinfection by-products. The imperative for environmentally friendly water disinfection methods has spurred the exploration of innovative solutions to mitigate microbial threats in water while simultaneously controlling the formation of harmful disinfection by-products (DBPs). This study introduces the combination of butanedione (BD) and solar irradiation as an effective method to inactivate pathogenic bacteria, including Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus . Acetyl radicals produced by solar activation of BD homolytic cleavage combined with dissolved oxygen to form acetyl peroxyl radicals, which were the main reactive species in the disinfection process. These acetyl peroxyl radicals attack bacterial cell membranes, escalate intracellular reactive oxygen species, and induce oxidative degradation of vital intracellular components such as enzymes and nucleic acids. Remarkably, the BD/Solar system demonstrated exceptional disinfection efficacy across a range of water quality parameters, achieving rate constants that were 5.2–98.1 times greater than those of other advanced disinfection processes that utilize H 2 O 2 , peroxydisulfate, or periodate in combination with solar irradiation. Notably, there was no evidence of bacterial regrowth and no formation of typical halogenated DBPs after treatment. These findings highlight the potential of this novel solar-powered system as a green approach for controlling environmental pathogens in a variety of waters, especially in sunlit swimming pools.