Inorganic impurity removal from waste oil and wash-down water by Acinetobacter johnsonii.

The removal of the abundant inorganic impurities in waste oil has been one of the most significant issues in waste oil reclamation. Acinetobacter johnsonii isolated from waste oil in aerobic process was employed to remove the inorganic impurities in waste oil and wash-down water. The biological process was developed through the primary mechanism research on the impurity removal and the optimization of the various parameters, such as inoculum type, inoculum volume and disposal temperature and time. The results showed that waste oil and wash-down water were effectively cleansed under the optimized conditions, with inorganic impurity and turbidity below 0.5% and 100 NTU from the initial values of 2% and 300 NTU, respectively. Sulfide, the main hazardous matter during waste oil reclamation, was also reduced within 1mg/L. After the biotreatment, the oil-water interface was clear in favor of its separation to benefit the smooth reclamation of waste oil and wash-down water.