Study on the Treatment of Oil Wastewater by Demulsification and O₃/H₂O₂ Combined Process

The oil wastewater from a fuel oil reservoir in Tianjin was selected as the research object.The combined process of demulsification and O₃/H₂O₂ advanced oxidation and activated carbon adsorption advanced treatment was selected.The research results showed that the demulsification effect was the best when the reaction temperature was 25℃,the reaction time was 25 min,the dosage of PAM was 1 mg/L,the pH was 7 and the dosage of demulsifier was 0.4%.The removal rate of COD and petroleum was 56.5%.O₃/H₂O₂ oxidation process was found the removal effect of COD and petroleum reached the ideal effect when the temperature was 25℃,pH was 8±0.2,O₃ flow rate was 2.5 L/min,mass concentration was 26 mg/L,H₂O₂ dosage was 0.56 g/L and reaction time was 60 min,.The removal rates of COD and petroleum were 69.25%and 79.83%,respectively.In the advanced treatment process,the mass ratio of activated carbon to wastewater was 1:10,and the adsorption equilibrium time was 15min.The removal rates of COD and petroleum were 41.17%and 93.72%,respectively.After combined treatment,the effluent COD and petroleum concentrations were 289.4 mg/L and 0.33mg/L,respectively.It met the Class B standard of GB/T 31962—2015 and the Class 3 discharge standard of Tianjin Municipal Sewage Comprehensive Discharge Standard （DB 12/356—2018）,which provided theoretical support for industrial treatment of the wastewater.