Chemical oxidation methods for treatment of real industrial olive oil mill wastewater

High organic load (up to 36.7g O-2/L) and the presence of phenolic compounds (up to 0.460 g/L) characterize olive oil mill wastewaters (OMW). The oxidative degradation of the OMW was investigated by means of three methods (ultraviolet light 'UV', UV/H2O2 and UV/H2O2/TiO2 using different catalyst concentration). Instantaneous reactions were registered and the degradation occurs on one-step during a few minutes (1-2 min). Phenolic compounds degradation by photocatalytic reaction has occurred in two-step reaction, the first was instantaneous, whereas the second was slower fitting to a second order reaction. For all oxidation systems used, the conversion degree on total organic carbon during the photoreaction time was fitted to pseudo-first order model, registering a reaction constant value equal to 3.72 and 37.9 1/h for UV and UV/H2O2 systems, respectively. In the photocatalytic system the reaction constant values varied along with the catalyst concentration studied (TiO2 concentrations = 0.12, 0.25, 0.50, 1.00, 1.50, 2.00 and 3.00 g/L) among 2.70 and 10.5 1/h. (C) 2019 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.