Catalytic wet air oxidation of wastewater from acid removal system

In this study, wet air oxidation of spent caustic waste water, generated from acid removal unit, was used for this study. The rate of reaction in oxidation was enhanced by catalyst. First, the kinetic model of non-catalytic wet air oxidation was investigated. From the reaction, the kinetic model was function of concentration of sodium sulfide, which is a main pollutant, at order of 2.10 and was function of oxygen at order of 0.87. The activation energy was 16.24 kJ/mol. Then, metals such as copper, manganese, ruthenium or vanadium on silica, alumina, ceria or titania were used as catalysts for determining the oxidation activity in the waste water. The weights of metal loading were based on the same cost of metals. From the reaction, copper metal on titania support was the most active catalyst among the others catalysts. After that, kinetic model of catalytic wet air oxidation was investigated. From the reaction, the kinetic model was function of concentration of sodium sulfide at order of 1.50 and was function of oxygen at order of 1.13. The activation energy in case of catalytic wet air oxidation was decreased to 11.09 kJ/mol. Finally, feasibility of the project was studied. Catalytic wet air oxidation can reduced the investment cost from 1,117,400 baht to 53,744 baht. However, more detail to determine life time of the copper on titania catalyst should be considered.