Photocatalytic disinfection of household well water using semiconductor nanocomposites

Abstract Composite materials are less explored outside of sewage water treatment. This study aimed to synthesize ZnO/TiO₂-based photocatalyst composites, including activated fly ash (aCFA) through co-precipitation–solvothermal methods and to investigate the effectiveness of the composites in removing bacteria from well water at the point of use. The standard microbiological pour-plate technique was used to preliminarily assess household water samples ( n = 256) for total bacterial count (TBC), coliform count (TCC), and Escherichia coli count (TEC). Of the 256 drinking water samples initially assessed, 10 highly contaminated samples were purposively disinfected with photocatalytic nanoparticles in sunlight and darkness and reassessed for TBC, TCC, and TEC at times t = 2, 4 and 6 h. Preliminary analysis revealed a poor microbiological water quality, as 161/256 (62.89%) water samples were fecally contaminated (TEC > 1 CFU/mL). Post-photocatalytic water disinfection showed significant differences in TBC, TCC, and TEC reduction ( p <0.0001), while TiO₂-BiOI-aCFA was the most effective. The nanoparticles at least exhibited a bacteriostatic effect against E. coli in the treated water samples, providing valuable insights into the future application of photocatalytic nanoparticles as an alternative water disinfection method.