Evaluation of Acinetobacter calcoaceticus, Bacillus subtilis and Pseudomonas for Deemulsification of Water-Oil Emulsions

Generation of water - oil emulsion is one of the major problems associated with the petroleum industry. In recent years, biological methods have attracted great interest in separation of water – oil emulsions. At present study, three bacterial strains of Bacillus subtilis, Acinetobacter calcoaceticus and Pseudomonas have been utilized for phase separation of oilfield emulsion. Supernatant of these bacteria exhibited high de-emulsification activity with %95, %90 and %86 de-emulsification of an oil-in-water emulsion within 144 h respectively. Biomass of these three bacteria could separate %76، %70 and %65 of emulsion within 144 h respectively. Then BATH method has been set for determining the relative hydrophobicity of bacteria. According to this test, Bacillus subtilis, Acinetobacter and Pseudomonas have hydrophobicity of 0. 7, 0. 3 and 0. 17. The above tests show that Bacillus subtillis is a better microorganism for separation of oil – water emulsions.