Abstract
Two strains of Bacillus species, namely BS-I and BS-II were used to degrade the crude oil samples. The ability of these strains and their mixed culture to produce gases, organic acids and other solvents were monitored. Under anaerobic conditions, both the strains produced considerable gases. BS-I produced 287 cc of gas per week accompanied by lowering the pH of the system and an oil consumption up to 56%. On the other hand, BS-II produced 353 cc of gas per week with lowering of pH and oil consumption up to 16%. In mixed strains, 240 cc of gas was produced with lowering of pH and an oil consumption of 16%. Four gases, namely CO2, N2, O2 and C3H8 were identified by gas chromatography. Carbon dioxide was produced in major amounts in all the cases. Nine organic acids were also identified in molasses based medium. These were quantified by GLC technique using standards as reference sources. In sand packed columns, the oil recovery efficiency was calculated to be 83% in the case of BS-II.
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Acknowledgment
The authors gratefully thank Dr. A. Hammed from the Microbiology Labs, Quaid-I-Azam University, Islamabad, for providing us the bacterial strains for this work.