Kinetics of Synthetic Wastewater Oxidation in Supercritical Water.

Supercritical water oxidation (SCWO) has been recognized as one of the most promising technologies for the decomposition of a variety of wastes. It utilizes the unique characteristics of water above its critical point (374.15°C, 22.12 MPa) and the whole process and final products are environmentally innocuous. Kinetic analysis of waste destruction in SCWO is important to properly design the process and reactor. In this paper we focused on the treatment of synthetic sewage wastewater by SCWO. A batch reactor was employed to carry out the experiments at 663 K, 683 K, and 703 K and 35 wt.% hydrogen peroxide was used as an oxidant. Chemical Oxygen Demand (COD) measurement was performed on both initial feed and liquidphase products. The activation energy was determined to be 57.335 kJ mol^-1 for the reduction of COD, when analyzed by nonlinear least squares technique. The comparison made between observed conversions and calculated values demonstrated favorable fit of the data provided by the estimated parameters. The proposed model was compared with those of other works treating municipal sewage with SCWO. It was found that the activation energy obtained by our experimental results is close to those reported by other studies. Differences in some parameters were possibly due to the different reaction conditions. [ABSTRACT FROM AUTHOR]