Intensification of catalytic wet air oxidation for industrial effluent treatment using ozone and ultrasound as pretreatment

摘要

The current work deals with the application of combined oxidation schemes (ozone, ultrasound and wet air oxidation) for improving the treatment of an industrial wastewater. The effect of temperature (150-180(omicron)C), oxygen pressure (1.42-1.92 MPa), catalyst dosage (0.1-0.2 kg m(-3)) and type of catalyst (activated charcoal and ruthenium on carbon) on the reduction in chemical oxygen demand (COD) of a real industrial wastewater has been investigated initially. Under the optimized set of operating parameters (temperature as 180(omicron)C, total pressure as 1.92 MPa and catalyst loading as 0.2 kg m(-3)), pretreatment using ozone, ultrasound and combination of ozone and ultrasound has been applied with an objective of intensification. The combination of ozone and ultrasonic irradiation followed by catalytic wet air oxidation (CWAO) effectively intensified the mineralization of industrial wastewater giving 80% COD reduction as compared with 60% COD reduction for the case of CWAO alone. The pretreatment also enabled use of less stringent conditions for obtaining similar levels of mineralization. Overall, the work has clearly demonstrated the beneficial results of combining ozonation and ultrasound with CWAO.