The Treatment Of Ethylene Spent Caustic By Catalytic Wet Air Oxidation

Ethylene spent caustic is a kind of wastewater which contains high concentration of sulfide and organic compound. It must be pretreated because it can’t be treated directly by biochemical technology. In this work, this wastewater was treated by catalytic wet air oxidation technology. Experiment was carried out in a stirred autoclave. Tannic acid was chosen as catalyst because it had high activity, low toxicity and was cheap. The effects of concentration of catalyst, temperature, oxygen partial pressure, gas flow rate and pH value were studied respectively. The kinetics of catalytic wet air oxidation was studied and the kinetic model was established. The results showed that the suitable reaction conditions were temperature of90℃, oxygen partial pressure of0.3MPa, pH10, catalyst concentration of0.8g/L, oxygen flow rate of4L/h and reaction time of2h. Ethylene spent caustic from Shanghai petrochemical company was treated under the suitable conditions. The sodium sulfide and COD of the wastewater decreased significantly. The conversion of sodium sulfide was about99.5%and the removal rate of COD was above80%. After treatment, the value of BOD5/CODcr of wastewater was0.4, which met the standard of biochemical treatment. According to the experimental data, the kinetic model was fitted and the reaction rate equation was:...