Decontamination of cork wastewaters by solar-photo-Fenton process using cork bleaching wastewater as H2O2 source

Abstract

This paper reports on a treatment strategy of cork wastewaters through the design of a solar-photo-Fenton process using cork bleaching wastewater as hydrogen peroxide (H2O2) source, as a pre-oxidation step, before a conventional biological oxidation process. This method proved to be efficient, achieving mineralization rates higher than 90% for different iron concentrations (20-80 mg Fe L-1). Higher iron concentrations resulted in the lower energy consumption and 60 mg Fe L-1 was selected as the optimum dose for 91% mineralization and used for biodegradability studies. According to the Zahn-Wellens test, the optimum phototreatment energy to achieve a biodegradable effluent is 13.6 kJ(UV) L-1 (65% mineralization), which corresponds to H2O2 consumption of 76.1 mM (approximately 8.5 L of cork bleaching wastewater (at 7.7g H2O2 L-1) for 15 L of cork boiling wastewater).