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 H2O2/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.