Bench-Scale Production of Biosurfactants and their Potential in Ex-Situ MEOR Application

The fermentative production of biosurfactants by five Bacillus strains in a bench-scale bioreactor and evaluation of biosurfactant-based enhanced oil recovery using sand pack columns were investigated. Adjusting the initial dissolved oxygen to 100% saturation, without any further control and with collection of foam and recycling of biomass, gave higher biosurfactant production. The microorganisms were able to produce biosurfactants, thus reducing the surface tension and interfacial tension to 28 mN/m and 5.8-0.5 mN/m, respectively, in less than 10 hours. The crude surfactant concentration of 0.08-1.1 g/L, and critical micelle concentration (CMC) values of 19.4-39 mg/L, corresponding to the biosurfactants produced by the different Bacillus strains, were observed. The efficiency of crude biosurfactant preparation obtained from Bacillus strains for enhanced oil recovery, by sand pack column studies, revealed it to vary from 30.22-34.19% of the water flood residual oil saturation. The results are indicative of the potential of the strains for the development of ex-situ, microbial-enhanced, oil recovery processes.