ABSTRACT
As a class of endocrine disrupting compounds (EDCs), corticosteroids (CSs) have attracted increasing attention due to their large excretion masses and toxic effects. However, compared to the very well-studied estrogens and androgens, few studies have been made dealing with the removal of CSs at environmentally relevant concentrations using advanced water and wastewater treatment processes. In this study, degradation performances of 26 natural and synthetic CSs in secondary effluent at environmentally relevant concentrations were comparatively investigated during UV/free chlorine (UV/Cl-2), UV/monochloramine (UV/NH2Cl) and UV/hydrogen peroxide (UV/H2O2) treatments. The 26 CSs could be divided into two groups: UV sensitive CSs, which have two double bonds in ring A (Delta(1,4)), and UV insensitive CSs, which have only one double bond in ring A (Delta(4)). The UV sensitive CSs could be effectively removed (removal efficiency >60%) by a UV dose of 100 mJ cm(-2) while the UV insensitive CSs could be removed (removal efficiency >40%) by a UV dose of 800 mJ cm(-2). The removal efficiencies of UV insensitive CSs increased with the increase of UV dose. Most of the CSs were poorly removed by sole Cl-2, NH2Cl, or H2O2 treatment (removal efficiency <40%). However, the addition of Cl-2, NH2Cl, and H2O2 promoted the UV degradation of CSs, especially for UV-insensitive CSs. UV photolysis would be the predominant mechanism in the UV/Cl-2, UV/NH2Cl, and UV/H2O2 processes for removing CSs in water. Besides the UV photolysis, HO radicals also functioned for CS removal. Compared with the insignificant effects of reactive chlorine species (RCS), the reactive nitrogen species (RNS) showed obvious selectivity in CS degradation. This study expanded the UV induced oxidation performances of CSs, which lays a foundation for exploring degradation mechanisms and eliminating the pollution from CSs.
ABSTRACT
In the context of the SARS-CoV-2 pandemic, reuse of surgical masks and filtering facepiece respirators has been recommended. Their reuse necessitates procedures to inactivate contaminating human respiratory and oral pathogens. We previously demonstrated decontamination of masks and respirators contaminated with an infectious SARS-CoV-2 surrogate via ultraviolet germicidal irradiation, vaporised hydrogen peroxide, and use of dry heat. Here, we show that these same methods efficiently inactivate a more resistant, non-enveloped oral virus; decontamination of infectious murine norovirus-contaminated masks and respirators reduced viral titres by over four orders of magnitude on mask or respirator coupons.
ABSTRACT
BACKGROUND: In the context of the ongoing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic, the supply of personal protective equipment remains under severe strain. To address this issue, re-use of surgical face masks and filtering facepiece respirators has been recommended; prior decontamination is paramount to their re-use. AIM: We aim to provide information on the effects of three decontamination procedures on porcine respiratory coronavirus (PRCV)-contaminated masks and respirators, presenting a stable model for infectious coronavirus decontamination of these typically single-use-only products. METHODS: Surgical masks and filtering facepiece respirator coupons and straps were inoculated with infectious PRCV and submitted to three decontamination treatments, ultraviolet (UV) irradiation, vaporized H2O2, and dry heat treatment. Viruses were recovered from sample materials and viral titres were measured in swine testicle cells. FINDINGS: UV irradiation, vaporized H2O2 and dry heat reduced infectious PRCV by more than three orders of magnitude on mask and respirator coupons and rendered it undetectable in all decontamination assays. CONCLUSION: This is the first description of stable disinfection of face masks and filtering facepiece respirators contaminated with an infectious SARS-CoV-2 surrogate using UV irradiation, vaporized H2O2 and dry heat treatment. The three methods permit demonstration of a loss of infectivity by more than three orders of magnitude of an infectious coronavirus in line with the United States Food and Drug Administration policy regarding face masks and respirators. It presents advantages of uncomplicated manipulation and utilization in a BSL2 facility, therefore being easily adaptable to other respirator and mask types.