The hydrocarbon contents of the crude oil and UAnSFB effluents were identified by GC/MS analysis performed using Tasquinimod 7890A Agilent gas chromatograph (Agilent Technologies Co. Ltd., USA) fitted with a DP5-MS capillary column (30 m × 0.25 mm i.d. × 0.25 μm film thickness), coupled with a 5975C Agilent mass detector, and controlled by the MSD Productivity ChemStation software (Agilent Technologies). Pure helium was used as the carrier gas at a flow rate of 1 mL/min and injection volume of 2 μL. Temperatures of the injector and MS detector were adjusted to 280 °C and 290 °C. An initial oven temperature of 50 °C was maintained for 1 min, and then increased 12 °C/min to 280 °C and held for 20 min. The biomass concentration in the sludge blanket was measured as the suspended solids according to the procedure described in the standard methods . To determine the amount of biomass in the UAnSFB, the total media was withdrawn from the bioreactor at the end of the study, air dried for 24 h, and then weighed. The difference between the weight of the dried biomass-loaded media pieces and their initial weight (clean media) accounted for the amount of biomass in the UAnSFB. All other analytical measurements were conducted according to standard methods .