Abstract: Oily siudge is an important part of solid pollutants in Xinjiang Oilfield. The reduction and harmlessness of oily sludge are of great significance for the control and treatment of oil pollution. In order to solve this problem, the oily sludge of Xingang Company in Xinjiang Oilfield was treated by the combination of biological agent cleaning and microbial degradation treatment, so that the oil content of oily sludge was effectively removed. The optimal reaction parameters were obtained by single factor experiment and response surface methodology (RSM). The initial oil content was 28.23%, the oil content was 6.48% after single factor optimization, and 3.04% after response surface optimization. Furthermore, Bacillus subtilis XG02 was used to degrade the oily sludge after the oily sludge was washed by the biological agent. After 20 days, the oil content of the sludge was only 0.45%, which could meet the requirements of mineral oil in the pollution control requirements of DB65/T 3998—2017.

Key words: oily sludge, biological agent, response surface optimization, microbial degradation