Photo-oxidation of cork manufacturing wastewater

Several photo-activated processes have been investigated for oxidation of a cork manufacturing wastewater. A comparative activity study is made between different homogeneous (H2O2/UV–Vis and H2O2/Fe2+/UV–Vis) and heterogeneous (TiO2/UV–Vis and TiO2/H2O2/UV–Vis) systems, with degradation performances being evaluated in terms of total organic carbon (TOC) removal. Results obtained in a batch photo-reactor show that photo-catalysis with TiO2 is not suitable for this kind of wastewater while the H2O2/UV–Vis oxidation process, for which the effect of some operating conditions was investigated, allows to remove 39% of TOC after 4 h of operation (for CH2O2=0.59 M, pH=10 and T=35 °C). The combined photo-activated process, i.e., using both TiO2 and H2O2, yields an overall TOC decrease of 46% (for CTiO2=1.0 g l−1). The photo-Fenton process proved to be the most efficient, proceeds at a much higher oxidation rate and allows to achieve 66% mineralization in just 10 min of reaction time (for CH2O2=0.31 M, T=30 °C, Fe2+:H2O2=0.12 (mol) and pH=3.2).