Inactivation of E. Coli and B. Subtilis by solar and solar/H 2O2 processes in humic surface waters

Abstract

The aim of the present study was to evaluate enhancing effects of H2O2 on the solar disinfection process of humic waters. Inactivations of E. coli and B. subtilis spores were determined in water samples containing various concentrations (0, 2 and 6 mg L-1) of fulvic acid (FA), which were exposed to the solar radiation in absence and presence of H2O2. Disinfection efficiencies of the solar and the solar/H2O2 processes were compared. The log reduction values varied between 3.6 and 6.5 for E. colt and 3.3 and 4.0 for B. subtilis spores, under all experimental conditions. B.subtilis spores appeared to be more resistant than E.coli against the solar and the solar/H2O2 disinfection processes. Although H2O2 with the solar radiation showed a synergistic effect on E. colt inactivation, a negligible effect was observed on the inactivation of B. subtilis spores. Fulvic acid was found to be more effective in protecting E. colt from solar and solar/H2O2 processes.