Study On The Preparation And Degradation Characteristics Of Immobilized Crude Oil Degrading Strains

With the economy developing, the crude oil pollution is becoming more and more serious. At the same time, the research on the treatment technology of the crude oil pollution is deeply and deeply. It is found that the degradation effect of crude oil is excellent with the bioremediation technology, and it has the advantages of simple operation, low cost, no second pollution to the environment and others.In this study, two highly efficient crude oil degrading strains were isolated from long-term crude oil contaminated soil, and prepared into immobilized crude oil-degrading inoculum. The optimal immobilization method and degradation conditions were obtained by the experiments of immobilized method selection and microbial degradation characteristics, and applied to the bioremediation of crude oil contaminated soil in laboratory. The results are as follows:1. In this study, two crude oil degrading strains were isolated from long-term crude oil contaminated soil in Songyuan, and named JL8 and JL10.The results of morphological observation, physiological and biochemical tests and molecular identification of 16 S r DNA revealed that the JL8 belongs to Pseudomonas putida, JL10 belongs to Pseudomonas aeruginosa. And both were surfactant producing strain.2. Selecting sodium alginate, polyvinyl alcohol and polyvinyl alcohol and sodium alginate mixture as carrier materials, the JL10 strain was prepared into immobilized inoculum, and applied for crude oil degradation test. The 10.0% polyvinyl alcohol and 1.0% sodium alginate mixture was selected as the the carrier material for preparation of immobilized inoculum by the study of the immobilized beads performance and its degradation rate. The ballability, mechanical properties and mass transfer performance of the immobilized crude oil degrading strain were good, and the degradation rate of crude oil was up to 81.77%.3. To improve the degradation rate of crude oil, selecting 10.0% polyvinyl alcohol, 1.0% sodium alginate and diatomaceous earth mixture and 10.0% polyvinyl alcohol, 1.0% sodium alginate and activated carbon mixture as carrier materials, the preparation method of immobilized inoculum was optimized. The results showed that the best method was as follows: the mixture of 10.0% polyvinyl alcohol, 1.0% sodium alginate and 10g/L diatomaceous was mixed with crude oil degrading bacteria(OD600=0.75) in equal volume, then droped into saturated boric acid of with 1.0% Ca Cl2 and immobilized 30 h.4. The results of optimization of degradation characteristics of immobilized crude oil degrading strains showed that the optimal immobilization degradation conditions of the JL 8 strain is immolized beads inoculum prepared with 10.0g/L crude oil and 1.0ml bacteria suspension, initial p H8.0 and 2.0% salt concentration, that of the JL10 strain is immolized beads inoculum prepared with 10.0g/L crude oil and 0.5ml bacteria suspension, initial p H9.0 and 2.0% salt concentration.5. Selecting 15 g corn stalk powder, and 5g diatomaceous earth as adsorbent, the two immobilized inoculum prepared with the JL8 and JL10 strains were used for the degradation experiments of crude oil contaminated soil in laboratory. The results showed that the crude oil degradation rate of the immobilized JL8 and JL10 strains were 95.98%、87.20% after 75 d biodegradation, respectively.In conclusion, the crude oil degrading rates of the two prepared immobilized inoculums were higer, and this provided a certain material basis for bioremediation of crude oil contaminated soil in the future.