Ozonation of an effluent of oil refineries for COD and sulfide removal

Wastewater treatment for water reuse is one of the main concerns in oil refineries since it can lead to high economic and environmental benefits. This paper deals with treatment of an effluents of Shiraz oil refinery called Slops reservoirs effluent by means of ozone as an advanced oxidation agent. For this purpose, ozone is well dispersed at a dose of 5g/h and effective transferred concentration of 2335mg/L using a gas distributor into a semi-batch reactor containing 1L of the wastewater. In order to determine the efficiency of the treatment, the removal percentage of COD and sulfide was selected as studying parameters. The effects of initial sulfide and COD concentrations, presence of UV light, initial pH, and temperature were investigated on the studying parameters. According to the obtained results, the highest removal rate occurred during the first 30min reaction time. Also it has been observed that, for the initial sulfide concentration of 350mg/L and the initial COD concentration of 975mg/L, the ozonation process after 45min resulted in 100% sulfide removal under optimum initial pH of 9.4 and optimum temperature of 15 degrees C and presence of UV light. While at the same conditions, 92% of COD removal has been achieved for 60min ozonation. Also, water turbidity level significantly reduced during the treatment.