Study of Pre-Treatment of Oil Refinery Wastewater by EEF-Enhanced Micro-Electrolysis

Oil refinery wastewater is rich in organic pollutants and cannot be treated easily. This study involves the pre-treatment of oil refinery wastewater by external electric field (EEF)-enhanced micro-electrolysis technology. The anode was titanium net plated with ruthenium, the cathode was barbed wire, and the Fe/C/Al micro-electrolysis filler as particle electrode. The optimum conditions for EEF-enhanced micro-electrolysis were determined to be as initial pH of 3.0, 10 V EEF voltage, and 0.06 mol/L electrolyte concentrations by studying the influence of different experimental parameters. It was also found that EEF-enhanced micro-electrolysis had a higher efficiency than the traditional micro-electrolysis in the degradation of the organic pollutants present in the oil refinery wastewater. Continuous running results showed the removal rate of COD (chemical oxygen demand), ammonia nitrogen and oil of the effluent was stable, and the average value of the effluent B/C (biochemical oxygen demand/chemical oxygen demand) ratio was 0.454 ± 0.013. The values of EC (energy consumption) and ICE (instantaneous current efficiency) were 9.8 kWh/Kg COD and 340.5%, respectively, when the reaction time was 60 min in oil refinery wastewater pre-treatment by EEF-enhanced micro-electrolysis technology. GC/MS was used to analyze the organic compounds present in the wastewater before and after treatment. UV-visible absorption spectroscopy was used to analyze the degradation process of the organic compounds present in the oil refinery wastewater. The results of these analyses confirmed the technical feasibility of EEF-enhanced micro-electrolysis in the pre-treatment of the oil refining wastewater. Finally, the main mechanism involved in the treatment of refinery wastewater by EEF-enhanced micro-electrolysis technology has been discussed.