Isolation and Optimization of Compound Bacteria for Wax Content and Particle Size

For removing wax and reducing viscosity of wax, microbial technology can effectively be used, and thereby, by using this technology, the flow properties of crude oil are improved. In this study, optimization of compound bacteria isolated from oil-contaminated soil and its effect on wax content and particle size are investigated. Moreover, experimental results show that the optimized compound bacteria have the highest cell density value under the optimal conditions. After #11 and #12 compound bacteria are added, the wax content reduces from 21.46% to 8.3%, and the wax removal rate becomes 61.32%. In addition, the polarizing microscope analysis demonstrates that the paraffin is degraded with the bacteria, and its wax crystal micro-structure is changed with the bacteria. Moreover, the focused beam reflectance measurement (FBRM) shows that the proportion of particles of large diameter is significantly decreased, and that of small ones is increased. Consequently, the flow properties of waxy crude oil are improved. The viscosity changes at different temperatures after treatment with bacteria. Finally, it is found out that at the temperature which is equal to 40 to 45 oC, the rate of viscosity reduction is higher than 60%. Therefore, the paraffinic hydrocarbons of crude oil can be degraded with compound bacteria, and their rheological properties are improved.