Soil Microbial Degradation of Vacuum Residue

Abstract

The effect of microbial consortia on the alteration of petroleum residual structure and portions was studied, which can propose an alternative or complementary method for stringent upgrading heavy crude oil methods, which consist of heavy and complex hydrocarbons. Biological processing of petroleum heavy fractions and residua may provide an alternative or complementary process in refining heavy crudes—the dominant refinery feed in the future—with less severe process conditions and higher selectivity to upgrade heavy fractions of crude oil. The primary objective was to observe the ability of an indigenous bacterial consortium taken from a soil bellow the vacuum column contaminated with vacuum residue (VR) for several decades from the Tehran refinery distillation unit, in degradation of residua components. Enrichment with VR, as sole source of carbon and energy, is the selected biosurfactant-producing microbial consortium. The biodegradation of net VR using indigenous consortia from this specific ecosystem was studied. The considered period of biodegradation of these heavy hydrocarbons was remarkably shorter than usual studies. Bacterial growth and VR biodegradation ability of this consortium analyzed with SARA test in 20 days. Studying the inoculum size and aeration effect revealed the significance of oxygen for this consortia activity and the similarity of 7% and 5% inoculation on alteration percentage of alkane, aromatic, and asphaltene and resin in VR. Results study revealed a 30.4%, 6.9%, and 9.4% decrease in the asphaltene, aromatics, and saturated aliphatic contents of VR, respectively, in only 20 days in 30°C at 150 rpm.