Water Treatment and Disinfection by Natural Solar Radiation in the Ferrous-Persulfate System

The simultaneous treatment and disinfection of natural water and municipal wastewater using solar-enhanced Fenton-like process was studied. Using herbicide atrazine and bacterium Escherichia coli as model pollutants, the kinetics of separate and simultaneous processes of destruction and inactivation in different aqueous matrices (deionized water – DW, lake water – LW and wastewater – WW) were studied in the ferrous-persulfate system, activated with natural solar radiation {Solar/Fe²+/S₂O₈²⁻}. It was found, that the presence of bacterial cells inhibited the rate of atrazine destruction in all water types, decreasing the pseudo-first-order rate constants by one order of magnitude. The accumulated solar doses (Q_UVA) for 90% atrazine removal from DW, NW and WW were 5.2, 5.7 and 9.2 kJ/L, respectively. By contrast, the presence of atrazine in NW and WW did not affect negatively on the E. coli inactivation rates. Inactivation of 95% cells was achieved (∼1.5 log reduction) at doses Q_UVA of 4-6 kJ/L, that is comparable with the literature data on E. coli inactivation in other oxidation systems. The combined method of simultaneous destruction of micropollutants and inactivation of microbial pathogens was proposed by using natural solar radiation in the ferrous-persulfate system.