Treatment of olive mill wastewater in supercritical water

The supercritical water oxidation (SCWO) process, decomposes organic compounds in wastewater without harmful by-products, seems to be an alternative technique to dispose of dangerous wastes. Supercritical water oxidation is performed using an oxidant above the temperature of 374.8°C and the pressure of 221.3 bar which are the critical temperature and pressure of water. Water has unique properties that the low values of density, dielectric constant and ionic product induce a non-polar solvent behaviour of water, when temperature and pressure are above the critical values for water. The aim of this work is to decompose organic compounds completely in olive oil mill wastewater at low residence times. The initial COD, TOC and O2 concentrations at reaction conditions ranged from 16.97 to 154.47 mmol/L, from 16.03 to 145.93 mmol/L, and from 147 to 588 mmol/L, respectively, by using hydrogen peroxide as the oxygen source. All experiments, except pyrolysis experiments, were carried out with excess O2. In different reaction conditions, COD and TOC conversions were obtained between 82.43?99.96% and %55.39-%100, respectively, at the reaction times between 5 and 30 s. Using experimental data obtained, the hypothesis of various oxidation kinetics were proposed, and the reaction models were developed. Keywords: Supercritical water, treatment of olive oil mill, oxidation, reaction kinetics.