Treatment of Alkaline Wastewater from Oil Refinery Using Circulating Biological Aerated Filter

The alkaline wastewater from oil refinery is a high concentration alkaline wastewater, which contains a great deal of sulfide, phenol and oil pollutants. A novel two stage circulating biological aerated filter (CBAF) was used to treat the alkaline wastewater after its neutralization. The factors of various air/water volumetric ratio, hydraulic retention time (HRT), which affected the removal of COD, sulfide, phenol and oil pollutants were investigated. The experimental results show that, when the wastewater feed flow rate is 0.5 m³·h^-1, the air/water volumetric ratio is 24:1 with the HRT of 4 h for single CBAF reactor, the influent average concentrations of COD, sulfide, phenol and oil pollutants are 1371, 234, 181 and 81.4 mg-L^-1, respectively. After two stage CBAF reactor treatment, the total average removal rates of COD, sulfide, phenol and oil pollutants are 72.0, 98.8, 79.6 and 85.2%, respectively. And the average effluent concentration of COD, sulfide, phenol and oil pollutants are 384, 2.90, 37.0 and 12.0 mg·L^-1, respectively. The results demonstrate that the CBAF reactor is a kind of high efficiency and low cost treatment technique which has a good application foreground for the treatment of the alkaline wastewater from oil refinery.