Efficiencies of solar light, solar/H2O2 and solar photo-Fenton processes for disinfection of turbid wastewaters

The effect of turbidity on wastewater disinfection by solar light, solar/H2O2 and solar photo-Fenton processes was investigated. The current work focused mainly on the enhancement of disinfection efficiency of turbid wastewaters by the application of solar-based advanced oxidation processes. Inactivation of Escherichia coli and Bacillus subtilis spores were evaluated in domestic wastewater at different turbidity levels. In total, 50 and 30 mg/L of hydrogen peroxide concentrations were used for solar/H2O2 and solar photo-Fenton processes, respectively. Results showed that E. coli removal by solar light process decreased significantly from a maximum of 4.24-log to a minimum of 1.38-log with increasing turbidity levels of 0.2, 30 and 150 nephelometric turbidity unit. However, with the application of solar/H2O2 and solar photo-Fenton processes, disinfection efficiencies increased and substantially higher E. coli removals were obtained. The synergistic effect of solar light and hydroxyl radicals overcame the adverse effect of turbidity. Inactivation levels of B. subtilis spores did not change significantly by the application of solar-based advanced oxidation processes. The best E. coli inactivation level in turbid wastewaters was achieved with solar photo-Fenton process.