Solar photocatalytic disinfection of well water using immobilized TiO$_2$: A comparative field study with SODIS in Antananarivo

TL;DR

This study demonstrates that a simple, low-cost solar photocatalytic reactor with immobilized TiO₂ effectively disinfects well water contaminated with fecal coliforms within 10 minutes, outperforming traditional SODIS methods in Madagascar.

Contribution

It introduces a straightforward, affordable TiO₂ coating method for solar disinfection, showing significant improvements over conventional SODIS in real-world rural water treatment.

Findings

Complete inactivation of fecal coliforms within 10 minutes of solar exposure.

TiO₂ coating accelerates bacterial disinfection compared to SODIS.

Disinfection effectiveness is consistent despite variations in water turbidity and pH.

Abstract

Access to safe drinking water remains a major challenge in rural areas of developing countries. This study investigates the feasibility of a simple, low-cost solar photocatalytic reactor coated with commercial titanium dioxide (TiO$_2$) for the disinfection of well water contaminated with fecal coliforms. A TiO$_2$ film was deposited on a glass plate using a straightforward acetone slurry method and exposed to natural sunlight in Antananarivo, Madagascar. The efficiency was compared to the conventional SODIS method (solar disinfection without catalyst). Water samples from ten different wells were characterized for physicochemical parameters and bacteriological quality. After only 10 minutes of solar exposure, the photocatalytic reactor achieved complete inactivation (0 CFU/100 mL) of fecal coliforms for all ten samples tested, whereas the SODIS control only reduced the initial count by approximately $51\%$ in a representative sample. While disinfection kinetics varied slightly with water turbidity and pH, complete inactivation was consistently achieved. The results demonstrate that even a non-uniform, low-purity TiO$_2$ coating significantly accelerates bacterial disinfection under solar radiation, offering a promising and affordable household-scale treatment technology for low-resource settings.