Potential of UV-B and UV-C irradiation in disinfecting microorganisms and removing N-nitrosodimethylamine and 1, 4-dioxane for potable water reuse: A review. (January 2022) - Minh Tran, Hai Duc
Abstract: The ultraviolet (UV)-based advanced oxidation process (AOP) is a powerful technology for removing pathogenic microorganisms and contaminants of emerging concern (CECs) from water. AOP in potable water reuse has been predominantly based on traditional low-pressure mercury (LP-Hg) lamps at 254 nm wavelength, supplemented by hydrogen peroxide addition. In this review, we assessed the potential of unconventional UV wavelengths (UV–B, 280–315 nm and UV-C, 100–280 nm) compared to conventional one (254 nm) in achieving the attenuation of pathogens and CECs. At the same UV doses, conventional 254 nm LP-Hg lamps and other sources such as, 222 nm KrCl lamps and 265 nm UV-LEDs, showed similar disinfection capability for viruses, protozoa, and bacteria, and the effect of hydrogen peroxide (H2 O2 ) addition on disinfection remained unclear. The attenuation levels of key CECs in potable water reuse ( N -nitrosodimethylamine and 1, 4-dioxane) by 185 + 254 nm LP-Hg or 222 nm KrCl lamps were generally greater than those by conventional 254 nm LP-Hg and other UV lamps. CEC degradation was generally enhanced by H2 O2 addition. Overall, our review suggests that 222 nm KrCl or 185 + 254 nm LP-Hg lamps with the addition of H2 O2 would be the best alternative to conventional 254 nm LP-Hg lamps for achieving target removal levels of both pathogens and CECs in potable water reuse. Highlights: This review assessed the water-treatment potential of UV wavelengths beyond 254 nm. Disinfection efficiencies for viruses, protozoa, and bacteria were compared. Some unconventional UV lamps showed higher removals of NDMA and 1, 4-dioxane. UV doses for CEC inactivation were higher than those for pathogen removal. AOP using 185 + 254 nm LP-Hg or 222 nm KrCl lamp could be the best alternatives.