Assessment of solar photocatalysis using Ag/BiVO4 at pilot solar Compound Parabolic Collector for inactivation of pathogens in well water and secondary effluents

tAdvanced oxidation processes (AOPs), such as photocatalysis driven by natural sunlight have beendemonstrated to be a promising technology for degradation of hazardous chemical compounds and inac-tivation of microorganisms in water. Among already exiting photocatalysts, for solar water treatment,currently visible light-active photocatalysts such as bismuth vanadate (BiVO4), have received much atten-tion from researchers. This work reports on the capacity of new synthetized Ag modified BiVO4compositeto inactivate E. coli, E. faecalis and spores of F. solani in different water matrices. Proof of principle exper-iments performed at laboratory scale (200 mL of distilled water in stirred tank reactor) demonstratedthe capability of this photocatalyst to inactivate those pathogens. A range of Ag loadings were investi-gated, demonstrating that 15% of Ag was the best option for water disinfection under natural sunlight.Although, TiO2-P25 is a better material for the solar photocatalytic disinfection of water under real sun.The cytotoxic effect of Ag/BiVO4composites was investigated by testing its cytotoxicity in human dermalfibroblasts (HDF). This result was supported also by the lack of bactericidal effect of the composites as itwas demonstrated to not compromise the viability of E. coli, E. faecalis and F. solani spores in dark (1 g L−1of Ag(15%)/BiVO4) for 3 h in the case of E. coli and for 5 h for the others. Up-scaling the treatment to CPCflow-reactor of 10 L was successfully done in distilled water and well water; meanwhile inactivation ofmicroorganism in secondary effluent (SE) from a Municipal Wastewater Treatment Plant was achievedonly in the case of naturally occurring E. coli. Several concentrations of catalyst were investigated, andbest inactivation efficiency was found to be 1 g L−1for all microorganisms, solar reactors and water matri-ces. The influence of chemical composition of the water matrix was also investigated. The presence ofhigh concentrations of carbonates/bicarbonates (in well water) did not affect significantly the photocat-alytic efficiency; while natural organic matter (in SE) strongly limited the process probably due to thecompetitiveness for the radicals generated.