ABSTRACT
A bacterial strain [designated as Alcaligenes sp. MS- 103] isolated from oil sample of the Aghajari oilfield in the south of Iran, was able to produce an effective extracellular lipopolysaccharide biosurfactant [1.2 +/- 0.05 g/l] on molasses as a sole carbon source. The highest surface tension reduction to level 20 mN/m was achieved by biosurfactant produced by cells grown on molasses under optimum conditions. The optimum values of carbon to nitrogen ratio [C/N], salinity, pH and temperature for biosurfactant production were determined as 60:1, 7.5%, 7.0 and 50°C, respectively. Biosurfactant flooding experiments were carried out on both fractured and unfractured carbonate cores. The highest recovery of residual oil among different experiments was about 10.7% in the unfractured cores. Oil displacement indicates that recovery of crude oil can be increased by 9.2% from fractured core with a permeability of 12 mD. The results showed that the biosurfactant produced by Alcaligenes sp. MS- 103 has the potential for industrial applications and may be used in microbial enhanced oil recovery [MEOR]
Subject(s)
Surface-Active Agents , Petroleum , Surface TensionABSTRACT
An isolate from polluted soil identified as Aspergillus sp. MS-100 was able to consume vanadium oxide octaethyl porphyrin as a model for protoporphyrins in crude oil. The isolate degrades about 55% of vanadium oxide octaethyl porphyrin [VOOEP] under optimum conditions during 7 days. The release of more than 0.96 mgL-1 of free vanadium into the aqueous phase was confirmed using atomic absorption. By using the Taguchi experimental design method, the optimum values of pH, temperature and initial concentration of VOOEP were determined as 5.5, 30C, and 20 mg/l, respectively. The reduction of VOOEP in the culture medium was accelerated by Ag+ and inhibited by Zn2+ and EDTA. The Sn2+ and Pb2+ ions showed a stimulatory effect at 0.1 mM and an inhibitory effect at 1 mM