Treatment of wastewater for reuse using advanced oxidation process: a bacterial inactivation mechanism approach

The aim of this study was to explain by molecular pathways the kinetic differences between reuse water disinfection processes using UV-C radiation and OH • radicals. The Fenton reaction (which produces OH radicals) was found to be significantly more effective at inactivating of thermotolerant coliforms (TTC) than either H 2 O 2 /UV-C or direct UV-C, with constants of inactivation that were some 6- to 14-fold higher. The superiority of Fenton was attributed to the powerful action of OH • in disassembling the molecular structure of E. coli cell wall and inducing the collapse of the entire cell structure, as demonstrated via molecular mechanisms. Under optimized conditions, treatment of wastewater in a plant comprising an anaerobic hybrid reactor with intermittent sand filter followed by a Fenton process led to the removal of 97.2% TOC, 99.9% turbidity and 100% of TTC and the quality of the final effluent was appropriate for direct potable reuse.