Title : Comparative Study of Biosurfactants Production and Optimization using Bacillus Subtilis and Bacillus Licheniformis, and Environmental Aspects
Abstract:
Microorganisms provide a unique opportunity to make hydrocarbon production economically and environmentally considerate in a technique known as microbial enhanced oil recovery. Three main limitations affect the robustness of the synthetic surfactant flooding in oil reservoirs, which are environmental impacts, synthetic surfactant cost, and oil price. Increasing ecological concerns, biotechnology development, and the rise of more rigorous environmental laws have encouraged biosurfactants to be a potent alternative to synthetic surfactants existing in the market due to their biodegradability, low toxicity, and cost-effectiveness. This study was conducted to investigate the potential of the biosurfactants produced by indigenous bacteria isolated from the Egyptian oil fields, optimize their surface and emulsification activity to maximize the oil recovery, and analyse their environmental aspects for microbial enhanced oil recovery. The selected bacterial strains Bacillus licheniformis and Bacillus subtilis were grown in the new proposed nutrient medium H to optimize the surface activity of the produced biosurfactant. Comparative stability studies were performed for the produced biosurfactants under different conditions (temperature, salinity, and pH). The core flooding experiments were conducted to investigate the effect of produced biosurfactants in improving oil recovery. Finally, the environmental risk assessment of any possible threats of producing biosurfactants by the selected bacteria was performed. Results showed that the selected bacterial strains Bacillus licheniformis and Bacillus subtilis show their ability to produce effective biosurfactants that gave the maximum surface activity within 24 hours of incubation in the new proposed nutrient medium H, where the surface tension of water reduced from 71.8 mN/m to 27.13 mN/m and 25.74 mN/m, and similarly the interfacial tension of water against kerosene reduced from 48.4 mN/m to 1.27 mN/m and 0.38 mN/m, at Critical Micelle Concentration of 0.06 g/l and 0.04 g/l, Respectively. No significant change in the surface and emulsification activity of produced biosurfactants over a wide range of temperatures. The surface activity of produced biosurfactants was marginally affected by increasing the salt concentration up to 20% (w/v) NaCl, and pH values range 5-12. The emulsification activity of biosurfactants produced by Bacillus licheniformis and Bacillus subtilis showed a significant increase against long-chain hydrocarbons such as crude oil, which are 50.2% and 63.7%, respectively. The Bacillus licheniformis and Bacillus subtilis biosurfactants yield was found to be 2.47 g/l and 2.85 g/l, respectively. The core flooding tests show the potential of biosurfactants produced by Bacillus licheniformis and Bacillus subtilis to recover 31.41% and 39.35% of additional oil over the water flooding residual oil saturation under simulated reservoir conditions, respectively. This study reveals the potential of the selected indigenous bacterial strains Bacillus licheniformis and Bacillus subtilis to grow in the new proposed medium H and produce effective biosurfactants that could significantly improve oil recovery and retain more than 60% of their surface and emulsification activity under harsh reservoirs conditions. Besides the beneficial effects of the selected indigenous bacteria in producing effective biosurfactants, the performed environmental risk assessment reveals that it could be an outstanding tool to be used in enhanced oil recovery schemes and could lead to promoting environmental sustainability
What will the audience learn from your presentation?
- This study was conducted to investigate the potential of the biosurfactants produced by indigenous bacteria isolated from the Egyptian oil fields,
- This study was conducted to optimize the surface and emulsification activity of the produced biosurfactants to maximize the oil recovery
- This study was conducted to analyse the environmental aspects of the selected biosurfactants producing bacterial strains for microbial enhanced oil recovery.
