Simultaneously enhance the inactivation and inhibit the photoreactivation of fungal spores by the combination of UV-LEDs and chlorine: Kinetics and mechanisms

Qiqi Wan; Gang Wen; Ruihua Cao; Hui Zhao; Xiangqian Xu; Yuancheng Xia; Gehui Wu; Wei Lin; Jingyi Wang; Tinglin Huang

doi:10.1016/j.watres.2020.116143

Simultaneously enhance the inactivation and inhibit the photoreactivation of fungal spores by the combination of UV-LEDs and chlorine: Kinetics and mechanisms

Water Res. 2020 Oct 1:184:116143. doi: 10.1016/j.watres.2020.116143. Epub 2020 Jul 12.

Authors

Qiqi Wan¹, Gang Wen², Ruihua Cao¹, Hui Zhao¹, Xiangqian Xu¹, Yuancheng Xia¹, Gehui Wu¹, Wei Lin¹, Jingyi Wang¹, Tinglin Huang¹

Affiliations

¹ Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an, 710055, PR China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, PR China.
² Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an, 710055, PR China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, PR China. Electronic address: hitwengang@163.com.

PMID: 32688151
DOI: 10.1016/j.watres.2020.116143

Abstract

Waterborne fungi have been recognized as an emerging environmental contaminant in recent years. This work was to investigate the inactivation efficiency and mechanisms of ultraviolet light-emitting diodes (UV-LEDs)/chlorine (Cl₂) (265, 280 and 265/280 nm combination) and LPUV/Cl₂ (254 nm) treatments for three fungal species compared with individual disinfection processes. Control of photoreactivation for fungal species inactivated by UV-LEDs/Cl₂ and LPUV/Cl₂ was also evaluated. The results revealed that the combined UV-LEDs/Cl₂ and LPUV/Cl₂ processes, especially UV-LEDs/Cl₂, exhibited better inactivation performance compared to UV alone and Cl₂ alone based on the inactivation rate constants, and an evident synergistic effect was observed. For example, the inactivation rates for Penicillium polonicum in the processes of UV₂₆₅/Cl₂, UV₂₈₀/Cl₂, UV_265/280/Cl₂ and LPUV/Cl₂ was 0.142, 0.168, 0.174 and 0.106 cm²/mJ, respectively, which were all approximately 1.5-fold higher than that of UV alone. The synergistic effect of fungal spores inactivation by UV-LEDs/Cl₂ and LPUV/Cl₂ was due to the high level production of intracellular reactive oxygen species and the reaction of potential extracellular free radicals. Resistance of the tested fungal spores was as follows: Trichoderma harzianum < Penicillium polonicum < Aspergillus niger. In addition, the joint effect of DNA and other cellular damage resulted in the inhibition of photoreactivation of fungal spores inactivated by UV-LEDs/Cl₂ and LPUV/Cl₂ compared with that of fungal spore inactivated by UV alone. This study may provide reference for controlling the dissemination of waterborne fungi utilizing combined UV-LEDs and free chlorine processes.

Keywords: Combined UV-LEDs/Cl(2) process; Disinfection; Fungal spores; Photoreactivation; Synergistic effect.

MeSH terms

Chlorine*
Disinfection
Kinetics
Spores, Fungal
Ultraviolet Rays
Water Purification*

Substances

Chlorine