Fenton oxidation of cork cooking wastewater-overall kinetic analysis

In the present work, the possibility of using chemical oxidation through Fentonʹs reagent for the pre-treatment of cork cooking wastewaters was exploited. Aiming both the selection of the best operating conditions (pH, Fe2+:H2O2 ratio and initial H2O2 concentration) and the evaluation of the overall reaction kinetics, trials were performed in a batch reactor. Operating at pH= 3.2, H2O2 CONCENTRATION=10.6 g/L and Fe2+:H2O2 RATIO=1:5 (by weight), about 66.4% of total organic carbon (TOC), 87.3% of chemical oxygen demand (COD) and 70.2% of biochemical oxygen demand (BOD5) were removed and an increase of the BOD5/COD ratio from 0.27 to 0.63 was achieved. In the temperature range 20–50°C, the best performance was obtained at 30°C. The kinetic study was undertaken at different initial TOC concentrations and temperatures. Overall kinetics can be described by a second-order followed by a zero-order rate equation and the apparent kinetic constants at 30°C are k=2.3×104 L/mg min and k0=26.0 mg/L min, respectively. The experiments performed at different temperatures confirmed the global kinetic model and allowed to calculate the global activation energy for the secondorder reaction (70.7 kJ/mol).