Degradation of oily sludge by microwave–ultrasound-immobilized bacterial agent technique

Abstract

In order to more effectively remove petroleum hydrocarbons from oily sludge, in this study, we proposed a microwave ultrasound immobilized bacterial agent oily sludge degradation technology, and through experiments to explore the various factors affecting the degradation, the best process conditions were obtained to improve the oil degradation rate in oily sludge. The results of microwave ultrasonic pretreatment showed that under the optimized conditions, the maximum removal rate of oil and gas substances was 53.23%, and the crude oil recovery rate was 31.03%. The oil removal effect was significantly improved compared with the single treatment and the treatment without optimized reaction conditions. The results of further treatment with immobilized bacterial agent showed that the highest oil removal rates of biochemical sludge and oil sludge scum were 92.04% and 35.56%, respectively, after the optimal compound ratio of composite bacteria and the optimized preparation conditions of immobilized bacterial agent were used, and the oil removal effect was further improved. This study proved that microwave and ultrasound combined with a variety of microbial technologies can effectively improve the removal rate of petroleum hydrocarbons in oily sludge after optimizing the process conditions.