Inactivation of Candida albicans in Water Using Advanced Oxidation Processes

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Abstract
Pathogenic microorganisms such as bacteria, viruses, fungi and protozoa have played a central role in the safety of drinking water, since they spread easily in the water network, constituting a health risk for humans and animals. Currently in water treatments, advanced oxidative processes (AOPs) have been increasing in importance in the microbiological disinfection of water. The present study aimed to inactivate C. albicans, a commensal yeast species in Vertebrates that can cause disease, using AOPs. To achieve this objective, a powerful oxidant (hydrogen peroxide) was combined with UV radiation to promote the inactivation of C. albicans. Initially, the inactivation capacity of the H2O2 was assessed and it was verified that the application of 2.5 mM, 5 mM and 10 mM H2O2 reached a cell reduction of 3 log after 180, 360 and 300 min, respectively. Subsequently, the combination with UV-A radiation (λ = 365 nm) proved to be even more promising, as the H2O2 + UV-A system, using the same H2O2 concentrations, reached an inactivation of 3 log after 240, 180 and 60 min, respectively. These results support that UV-A radiation promotes the generation of hydroxyl radicals, which have a comparatively higher oxidation potential (2.8 eV) to the H2O2 (1.8 eV), responsible for the inactivation of C. albicans cells. Thus, the UV-A/H2O2 process can reduce this microorganism in an aqueous matrix, avoiding potential hazards to human and animal health.
Funding Information
  • OBTain—Objective Building Sustainability (NORTE-01-0145 FEDER-000084, UIDB/00616/2020, UID/AGR/04033/2020, BI/UTAD/67/2022)
  • Fundação para a Ciência e a Tecnologia (FCT) (NORTE-01-0145 FEDER-000084, UIDB/00616/2020, UID/AGR/04033/2020, BI/UTAD/67/2022)
  • CITAB (NORTE-01-0145 FEDER-000084, UIDB/00616/2020, UID/AGR/04033/2020, BI/UTAD/67/2022)
  • OBTain (NORTE-01-0145 FEDER-000084, UIDB/00616/2020, UID/AGR/04033/2020, BI/UTAD/67/2022)

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