Kinetic model for oxygen concentration dependence in the supercritical water oxidation of an industrial wastewater

The objective of this work was the determination of a global rate expression for the kinetics of the supercritical water oxidation (SCWO) of cutting fluid wastes generated in metal industries. SCWO experiments were carried out in a continuous flow reactor system using pure oxygen as the oxidant at a constant pressure of 25 MPa. The temperature effect was studied in the range 673–773 K. Oxygen excess coefficient was varied from n = 0.4 (60% of stoichiometric oxygen) to n = 1.2 (20% oxygen excess) to determine the reaction order for O2. The effectiveness of the process was monitored in terms of COD removal.The rate equation parameters were obtained by fitting of experimental data to the differential equation obtained using the Runge–Kutta algorithm. The kinetic model proposed allows the prediction of the COD conversion with respect to oxygen supply to optimize the operating conditions and to minimize investment and operating costs.