Evaluation of Indigenous Biosurfactant-producing Bacteria for De-emulsification of Crude Oil Emulsions
Olugbenga Adebanjo Falode *
Centre for Petroleum, Energy Economics and Law (CPEEL), University of Ibadan, Nigeria and Department of Petroleum Engineering, Faculty of Technology, University of Ibadan, Nigeria
Mariam Adebowale Adeleke
Centre for Petroleum, Energy Economics and Law (CPEEL), University of Ibadan, Nigeria
Adenike A. O. Ogunshe
Centre for Petroleum, Energy Economics and Law (CPEEL), University of Ibadan, Nigeria and Department of Microbiology, Faculty of Science, University of Ibadan, Nigeria
*Author to whom correspondence should be addressed.
Abstract
Conventional method of removing water from crude oil using chemicals is unfavourable from both the economic and environmental perspectives; so, this study aims at formulating economical and environmentally-friendly biosurfactant de-emulsifiers. Biosurfactant-producing bacteria isolated from oil-contaminated soil samples from Nigerian National Petroleum Corporation (NNPC) depot Apata, Ibadan, Oyo State of Nigeria were applied on crude oil emulsions for the purpose of separating water-in-crude oil emulsions. Thirty-five of 41 bacterial strains were further screened for ability to degrade (de-emulsify) hydrocarbon, using vapour transfer method. Highest displayed de-emulsification activities at 24 h were Pseudomonas sp. AGO1 (50.0%), Bacillus sp. DPK1A (50.0%), Bacillus subtilis AGO1A (50.0%), Pseudomonas aeruginosa DPK3A (55.7%) and Bacillus subtilis PMS1B2 (66.0%); and at 48 h were, Bacillus subtilis AGO1A (50.0%), Ps. aeruginosa DPK3A (60.0%) and Bacillus subtilis PMS1B2 (66.7%). Higher de-emulsification activities were recorded on supplementation of growth media, with Ps. aeruginosa DPK3A showing the highest de-emulsification activity of 66% when grown on growth media supplemented with glucose and yeast extract, at temperature of 60°C. In comparison with chemical de-emulsifier, microbial de-emulsifier produced 66%, 62% and 60% volume of water, while chemical de-emulsifier produced 63%, 60% and 66.2% volume of water. This study demonstrated that generally regarded as safe (GRAS), hydrocarbon-utilising, biosurfactant-producing bacteria, especially the Bacillus species isolated from crude oil-contaminated soils, when cultured on appropriate medium is effective in diesel degradation and treatment of water-in-crude oil emulsion; thus, reducing cost and environmental pollution.
Keywords: Biosurfactant bacteria, chemical de-emulsifiers, crude oil, de-emulsification activities, emulsification test