Inactivation of Escherichia coli, Bacteriophage MS2, and Bacillus Spores under UV/H₂O₂ and UV/Peroxydisulfate Advanced Disinfection Conditions

Ultraviolet light (UV) combined with peroxy chemicals, such as H₂O₂ and peroxydisulfate (PDS), have been considered potentially highly effective disinfection processes. This study investigated the inactivation of Escherichia coli, bacteriophage MS2, and Bacillus subtilis spores as surrogates for pathogens under UV/H₂O₂ and UV/PDS conditions, with the aim to provide further understanding of UV-based advanced disinfection processes (ADPs). Results showed that one additional log of inactivation of E. coli was achieved with 0.3 mM H₂O₂ or PDS at 5.2 × 10^–5 Einstein·L^–1 photo fluence (at 254 nm) compared with UV irradiation alone. Addition of H₂O₂ and PDS greatly enhanced the inactivation rate of MS2 by around 15 folds and 3 folds, respectively, whereas the inactivation of B. subtilis spores was slightly enhanced. Reactive species responsible for the inactivation were identified to be •OH, SO₄^·–, and CO₃^·– based on manipulation of solution conditions. The CT value of each reactive species was calculated with respect to each microbial surrogate, which showed that the disinfection efficacy ranked as •OH > SO₄^·– > CO₃^·– ≫ O₂^·–/HO₂^·. A comprehensive dynamic model was developed and successfully predicted the inactivation of the microbial surrogates in surface water and wastewater matrices. The concepts of UV-efficiency and EE/O were employed to provide a cost-effective evaluation for UV-based ADPs. Overall, the present study suggests that it will be beneficial to upgrade UV disinfection to UV/H₂O₂ ADP for the inactivation of viral pathogens.