Application of intensified Fenton oxidation to the treatment of hospital wastewater: Kinetics, ecotoxicity and disinfection

Abstract

Fenton oxidation has proved to be effective for the treatment of a real hospital wastewater. The intensification of the process viz. the improvement on the efficiency of H2O2 consumption, by increasing the temperature, is necessary to operate in a single step and avoid high reaction times and the need of large H2O2 and iron concentrations. This approach would allow taking advantage of the heat energy contained in the laundry stream since the washing process is performed at high temperature to assure disinfection of the hospital textiles. In this work, temperatures within the range of 50–90°C have been tested, which allowed an effective oxidation of the real wastewater ([COD]0=365mgL−1, [Phenols]0=8.4mgL−1, [total coliforms]0=4.16×106 MPN/100mL, 5 toxicity units) with the stoichiometric amount of H2O2 (1000mgL−1) and a relatively low iron concentration (25mgL−1 Fe3+). Operating at 90°C, complete disappearance of phenolic compounds and 70% and 50% reduction of COD and TOC were achieved in 1h reaction time. Time evolution of those global parameters were appropriately fitted to pseudo-first and second order kinetic equations, providing a useful approach for design purposes. The main by‐products were short-chain organic acids (oxalic and formic), being the final effluents non-toxic. Disinfection of the hospital wastewater was also achieved at all the operating temperatures tested, as confirmed by the absence of coliforms.