An Oil Reduction Study By Microbial Method

An oil reduction by streptococcus is introduced in this paper, including the study of the strain growth characteristics, the inocula preparation, the oil reduction experiments and 2D-glass micro model design and core experiment. Firstly, the important influencing factors of the strain growth characteristics are studied, including temperature, salinity, oxygen, etc. It is determined that the best growth conditions are 35℃, 5% inoculation, 2% salinity; Meanwhile, the microbial growth curve and extracellular polysaccharide generation curve are drawn in order to understand the microbial growth process and characteristics further. The results showed that the strain growth is divided into 4 parts, which are the short growth prophase, quickly growth during 1～20h and steady period which begins secondary metabolites generation stage after 14h growth. During the secondary metabolites generation stage, massive extracellular polysaccharide is generated, which increases the broth viscosity greatly.It is considered to prepare the inocula for reducing transport cost. We screen and optimize the method of inoculate preparation, and confirm it finally, which is centrifuged with 5% salinity at 8000rmp for 10min.Secondly, the method of performance evaluation has not been perfected right now and the bacterium mechanism isn't clear, we'll try to research on the streptococcus's characteristics and explain how the microorganism works in this paper. Combining this result with analyzing of the conditions of the oil viscosity reduction, we find the best conditions are 35℃, 160rpm, 5% inoculation, 14h effecting with oil after 10 h seed culture and the oil viscosity will reduce from 4000mPa·s to 500mPa·s. Finally, new design of 2D-glass micro model which simulates porous media of bottom layer and core experimental process, observes the result on line by UV scanning, could improve the traditional core experiment and make the test online observation and more simple. The result showed that the strain could not only degrade the oil, but also improve oil dispersion and fluidity. Meanwhile, the strain could effect on the oil during 24h after 2D-glass micro model saturated by water and high saline displacing, which proves the strain could be MEOR bacterium.