Treatment of oily sludge by two-stage wet air oxidation

Oily sludge produced in petrochemical industries contains a large amount of toxic and hazardous substances. High oil sludge yield and high treatment cost have become major obstacles to the development of the petrochemical industry. In this study, the treatment and disposal of oily sludge using the wet oxidation method was investigated. Firstly, the orthogonal optimization experiment was designed to discuss the influence of reaction time, reaction temperature, oxidant amount, and emulsion splitter amount on the removal efficiency of oil and sludge volume. On this basis, a two-stage wet air oxidation method was employed to treat oily sludge. The results show that the two-stage oxidation method could remove 93.1% oil from the oil sludge and reduce the volume of oil sludge by 85.4%. Furthermore, the oil sludge treated with wet oxidation could be more easily separated from water, and the waste oil could be recycled. The proposed two-stage wet oxidation method shows excellent performance in treating oily sludge, from which resources can be recycled while reducing the amount of sludge. (C) 2018 Energy Institute. Published by Elsevier Ltd. All rights reserved.