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In this work, the oxidation characteristics of synthetic sewage wastewater in supercritical water were investigated by using batch reactor with hydrogen peroxide as the oxidant over the temperature range of 663 K-703 K, oxidizer stoichiometry of 100%, 150%, and 250%, and reaction time of 1, 3, 5, and 10 mins. The liquids before and after reaction, which became odorless during the treatment, were analyzed to determine the chemical oxygen demand (COD) in accordance with HACH method 8000. Effects of reaction parameters including oxidant amount, reaction time, and temperature were examined. It was shown that a COD removal rate of 99.81% could be reached in 10min at 703 K with 150% O2 excess. Under the experimental conditions set up in this study, at any given temperature, the addition of more oxygen and the extension of reaction time could significantly improve the COD destruction efficiency. In line with the findings of many other research works into supercritical water oxidation (SCWO) of wastes, COD removal rate also increased as the temperature rose. The purpose of this work was to decide the optimal operating parameter values for SCWO of synthetic wastewater, based on which the most efficient operating conditions for municipal sewage destruction via SCWO could be estimated. [ABSTRACT FROM AUTHOR]

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]