The Study On Degradation Of Crude Oil By Immobilized Microorganism

The crude oil degradation by microorganism immobilization technology was studied. The main content of this study was to determine the best immobilization conditions; capability of reducing viscosity of crude oil by immobilized bacteria and immobilized mixed bacteria community; to analyze the changes of the compositions in crude oil degraded by immobilized bacteria; and to simply simulate crude oil degradation by immobilized bacteria in the off shore waters.The bacteria used in this study were Bacillus alcalophilus SG, Bacillus mucilaginosus JZ and Bacillus megaterium JD.The experiment showed that the degradation efficiency of crude oil by immobilized bacteria was better than that of by bacteria only. The removal rate of the crude oil by immobilized SG was 82.78%, which was higher than that of by SG only.The best immobilization conditions on crude oil degradation by immobilized bacteria were probed elementarily. The optimum carrier dosage was 25.0g/L (dry weight), the optimum immobilization time was 30h. When SG was immobilized on the stalk with pretreatment, the removal rate of the crude oil was very low, and the highest was only 24.30%. During the process of SG immobilization on stalk, adding inorganic salt ion to immobilization culture medium accelerated the removal rate of the crude oil.The study showed that oil-containing culture medium with different original pH became neutral or weak alkaline during the degradation of crude oil by immobilized strains. During the process of degradation of crude oil by immobilized mixed bacteria community, the pH of the synthetic seawater reaction system declined from 7.8 to between 6.2 and 6.5, the pH of the freshwater reaction system dropped a little, then raised with small margins, stabilized between 7.9 and 8.1 finally.The experimental results indicated that the immobilized strains were able to reduce the viscosity of crude oil. Between pH6 and pH10 the immobilized strain had good capability of reducing the viscosity of crude oil, the greatest depressed rate of the viscosity of crude oil was 31.97%. When the concentrations of sodium chloride were in the range of 5% to 7%, the depressed rate of the viscosity of crude oil were higher, the...