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 center dot 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 center dot 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.

Automated summary

This study aimed to explain the differences in kinetic between reuse water disinfection processes using UV-C radiation and OH center dot radicals through molecular pathways. The results showed that the Fenton reaction was significantly more effective in inactivating thermotolerant coliforms (TTC) compared to H2O2/UV-C or direct UV-C. This superiority was attributed to the powerful action of OH center dot in disassembling the molecular structure of E. coli cell wall and inducing the collapse of the entire cell structure, as demonstrated through molecular mechanisms. Under optimized conditions, treatment with an anaerobic hybrid reactor, intermittent sand filter, and Fenton process achieved high removal rates for TOC, turbidity, and TTC, making the final effluent suitable for direct potable reuse.