Economical and effective oily sludge pyrolysis residue was prepared, characterized with various techniques, and applied in the removal of COD in biologically treated oil-field wastewater. It was found that surface area of oily sludge pyrolysis residue was 223.62 m2 /g. The content of C and Al2O3 was 27.91% and 27.6%, respectively. Oily sludge pyrolysis residue contains carboxyl, hydroxyl, carbonyl and other oxygen-containing acid functional groups. When the adsorption equilibrium time of oily sludge pyrolysis residue was 90min, pH of solution was 4, the best COD adsorption capacity was 59.5 mg/g. Adsorption of oily sludge pyrolysis residue is determined by its structure and composition. The Al2O3 may play a flocculation and sedimentation role in COD removal, which has a synergistic effect on adsorption. The adsorption of COD from biologically treated oil-field wastewater by oily sludge pyrolysis residue follows Langmuir adsorption isotherm.
