Resumen
In the Philippines, an estimated 8.4 million rely on unsafe water sources where pathogens like E.coli thrive. Chlorination is conventionally used; however, it produces carcinogenic disinfection by-products. Thus, a solar-activated TiO2-CuO-SiO2 photocatalyst composite immobilized in waste polystyrene is proposed as an alternative for safely inactivating E.coli, the mandatory pathogen indicator, in water. The photocatalyst composite was prepared mainly by sonication and calcination then was immobilized in thin film form using waste polystyrene. In order to determine the efficiency of the photocatalyst in reducing E.coli concentration and to evaluate whether it is within the Philippine National Standards for Drinking Water (PNSDW) of 2017, the groundwater samples were characterized before and after 6 hours of solar irradiation. The highest photocatalytic inactivation was exhibited by PS-TiO2-CuO-SiO2 composite compared to PS-TiO2-CuO and PS-TiO2. PS-TiO2-CuO-SiO2 achieved almost 100% reduction of E.coli concentration from 24,000 to <1.1 MPN E.coli/100 ml. The results showed that the composite synergy between TiO2, CuO and SiO2, together with the homogeneous dispersion of the photocatalyst particles characterized by the EDS led to enhanced photocatalytic inactivation of E.coli. Furthermore, even if the pilot scale volumes were increased, the coliform concentrations were still reduced from 79 to <1.1 MPN / 100ml reaching almost 100%. The reusability of the catalyst was also studied. PS-TiO2-CuO-SiO2 can be reused for at most five times to reduce coliform concentration in water to the PNSDW standard while retaining almost 100% efficiency. The entirety of the research is simple, efficient, economical, environmental, sustainable and feasible for large scale and point of use applications to convert non-potable water into a safer drinking water without harmful disinfection by-products.