Photo-Fenton and TiO(2) Photocatalytic Inactivation of Model Microorganisms under UV-A; Comparative Efficacy and Optimization

Photocatalytic inactivation of pathogens in aqueous waste is gaining increasing attention. Several homogeneous and heterogeneous photocatalytic protocols exist using the Fenton’s reagent and TiO(2), respectively. A comprehensive study of homogeneous and heterogeneous photocatalysis on a range of microorganisms will significantly establish the most efficient method. Here, we report a comparative study of TiO(2)- and Fe(+3)-based photocatalytic inactivation under UV-A of diverse microorganisms, including Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria, bacterial spores (Bacillus stearothermophilus spores) and viruses (MS2). We also present data on the optimization of TiO(2) photocatalysis, including optimal catalyst concentration and H(2)O(2) supplementation. Our results indicate that both photo-Fenton and TiO(2) could be successfully applied for the management of microbial loads in liquids. Efficient microorganism inactivation is achieved with homogeneous photocatalysis (7 mg/L Fe(+3), 100 mg/L H(2)O(2), UV-A) in a shorter processing time compared to heterogeneous photocatalysis (0.5 g/L TiO(2), UV-A), whereas similar or shorter processing is required when heterogenous photocatalysis is performed using microorganism-specific optimized TiO(2) concentrations and H(2)O(2) supplementation (100 mg/L); higher H(2)O(2) concentrations further enhance the heterogenous photocatalytic inactivation efficiency. Our study provides a template protocol for the design and further application for large-scale photocatalytic approaches to inactivate pathogens in liquid biomedical waste.