Effective solar processes in fresh-cut wastewater disinfection: Inactivation of pathogenic E. coli O157:H7 and Salmonella enteritidis

Abstract

The disinfection of synthetic fresh-cut wastewater (SFCWW) by several solar processes has been investigated as an alternative to the commonly used chlorination in this industry. To this end, a SFCWW recipe was developed based on real sample analysis from the fresh-cut industry and literature data. It is characterized mainly by the presence of organic matter in solution (25mg/L DOC) and turbidity (100 NTU). The inactivation kinetics of human pathogenic bacteria (E. coli O157:H7 and Salmonella enteritidis) in SFCWW was assessed by solar photo-inactivation, H2O2/solar, iron/solar and solar photo-Fenton processes. Excellent inactivation performance was achieved in all cases demonstrating the capability of solar processes to disinfect water even at high levels of turbidity. The best bacterial inactivation rates were obtained with the H2O2/solar process (20mg/L) in less than 60min for both E. coli and S. enteriditis. Moreover, the influence of UVA irradiance (10–50W/m2) on the inactivation of both pathogens by the H2O2/solar process at several H2O2 concentrations was investigated. These results showed a slightly different response for both pathogens against UVA irradiance and H2O2 concentration: photo-limitation for both types of bacteria; while only E. coli was limited by the H2O2 concentrations investigated in this work.