Inactivation of E. coli and E. faecalis by solar photo-Fenton with EDDS complex at neutral pH in municipal wastewater effluents.

Photo-Fenton is a solar disinfection technology widely demonstrated to be effective to inactivate microorganisms in water by the combined effect of photoactivated iron species and the direct action of solar photons. Nevertheless, the precipitation of iron as ferric hydroxide at basic pH is the main disadvantage of this process. Thus, challenge in photo-Fenton is looking for alternatives to iron salts. Polycarboxylic acids, such as Ethylendiamine-N',N'-disuccinic acid (EDDS), can form strong complex with Fe and enhance the dissolution of iron in natural water through photochemical process. The aim of this study was to evaluate the disinfection effectiveness of solar photo-Fenton with and without EDDS in water. Several reagent concentrations were assessed, best bacterial (Escherichia coli and Enterococcus faecalis) inactivation was obtained with 0.1:0.2:0.3 mM (Fe:EDDS:HO) in isotonic water. The benefit of using EDDS complexes to increase the efficiency of kept dissolved iron in water at basic pH was proven. Solar disinfection and HO/solar with and without EDDS, and Fe:EDDS complexes were also investigated. Bacterial inactivation results in municipal wastewater effluents (MWWE) demonstrated that the competitive role of organic matter and inorganic compounds strongly affect the efficacy of Fe:EDDS at all concentrations tested, obtaining the fastest inactivation kinetics with HO/solar (0.3 mM).