Efficient treatment of swimming pool water by photoelectrocatalytic ozonation: Inactivation of Candida parapsilosis and mineralization of Benzophenone-3 and urea

Abstract

Swimming pool water (SPW) poses a potential risk to both human health and the environment due to the presence of contaminants of emerging concern (including components of sunscreens), pathogenic microorganisms, and eventually products of the reaction of chlorine with urea, such as chloramines, which are found in the water. The present work describes the efficient combination of photoelectrocatalysis and ozonation (PEC + O3) to treat both simulated and real contaminated pool water. An annular bubble reactor was designed based on a cylindrical TiO2 nanotubes electrode irradiated by an UVB 36 W lamp with an injection of ozone/air. Benzophenone-3 (BP-3) was used as a model of harmful commercial sunscreen to test the reactor efficiency. The results showed that O3-based treatment efficiently oxidized BP-3 (100% in 20 min) but reached only 32% of mineralization after 120 min of treatment, whereas O3 + PEC-based treatment reached 82% of TOC removal (with 100% BP-3 removal in 20 min). The addition of 106 CFU mL−1 of Candida parapsilosis did not interfere in BP-3 mineralization, and the fungus was found to be completely inactivated after 45 min of treatment. Furthermore, the presence of urea (10 and 20 mg L−1) was not found to exert any significant influence over BP-3 degradation. The method was successfully applied in real SPW sample fortified with 10.0 mg L−1 of Benzophenone-3. The findings show that O3 + PEC-based treatment could be a good alternative for SPW treatment, once it leads to efficient disinfection and mineralization of harmful organic compounds.