Biotreatment of oil sludge containing hydrocarbons by Proteus mirabilis SB

Abstract The release of petroleum hydrocarbons in the form of oil sludge poses a serious threat to people and the environment. At present, biodegradation of oily sludge is regarded as one of the most promising harmless treatment technologies, where the screening of high efficient degrading strains is the key to its implementation. In the present study, a strain Proteus mirabilis SB was isolated from oil sludge of Jingbian Oil Field. The strain grew and reproduced rapidly with petroleum hydrocarbon as the sole carbon source in the optimal growth temperature range of 30–35 °C, and salinity less than 6%. Its effective emulsification function was attributed to the production of biosurfactants, mainly rhamnolipids, through metabolism. Analysized by gas chromatography (GC) and four-fraction the degradation efficiency of total petroleum hydrocarbon (TPH) reached 70.5% within 2 weeks in the liquid culture medium, while the degradation efficiencies of saturated hydrocarbons, aromatics, resins and asphaltenes were 90.8%, 69.2%, 16.3% and 31.5%, respectively. For degrading petroleum hydrocarbons in oil sludge within a quasi-solid culture system under standard atmospheric conditions, a total degradation efficiency of 76.9% over 60 days was obtained, while 90.8% of saturated hydrocarbons and 69.2% of aromatics were degraded. Overall, the strain was capable of degrading petroleum hydrocarbons in both crude oil and oil sludge with high efficiencies This development demonstrated strong potential of Proteus mirabilis SB for oil sludge treatment and in situ bioremediation of crude oil contaminated soil/land.