Preparation And Characterization Of Immobilized Oil-degrading Strain

This paper aiming at the pollution status of oil to soil, the oil degrading bacteria named SM-3 which was selected from the oil contaminated soil was used as the fixed object, and different materials were selected as immobilization carrier, preparing immobilized bacteria by adsorption method and embedding method respectively. With oil degradation rate as the goal, the preparation conditions of immobilized microorganism had been studied, and the performance of the selected optimal immobilized microorganism was characterized. The results of adsorption method indicated that: Thirteen kinds of natural materials were chosen as immobilization carrier, by the comparing experiment, YJ-05 was identified as the best carrier material, with YJ-05 as the carrier material, the immobilized crude oil degrading bacteria's degradation rate on crude oil reached more than 61% in 7 days, which was 40% higher than the free bacteria; It also investigated external factor's influence on the absorption amount of bacteria and determined when the adsorption time was 15h, the temperature was 30℃, rotating speed was 160rpm and the volume of carrier was 10ml, both the immobilized rate and the degradation rate could reach the highest; The BET results of YJ-05 and YJ-07 showed that they had a simple mesoporous structure for 6¹3 nm, the surface area and volume of YJ-07 were better than YJ-05, so YJ-07 could also be considered as immobilized materials, it can explore a series of natural materials as immobilized carrier in terms of material structure; The results of scanning electron microscopy(SEM) showed that there was mainly columnar pore structure on YJ-05, the structure would become loose because of the degradation of the immobilized bacteria, and the immobilized microorganism with YJ-05 could satisfy the application of soil bioremediation to achieve the purpose of waste control by waste because of its pollution-free and without recycling. PVA-Na₂SO₄, PVA-H₃BO₃, chitosan and calcium alginate-chitosan were selected as carrier in embedding method, the optimum imbedding conditions of various methods were determined by the experiment and it draw conclusions as follows: The best embedding solution was PVA-Na₂SO₄ (activated carbon) microsphere, the optimum preparation conditions were PVA concentration 9%, calcium chloride concentration 1%, activated carbon 7% and reaction time was 3h, in which conditions the oil degradation rate was 58.25% and the microspheres had excellent mechanical strength, flexibility and permeability; Scanning electron microscopy (SEM) results showed that PVA-Na₂SO₄ (activated carbon) microsphere with the structure of loose inner and dense outside suitable for inputing and outputing of solute, the finding of YJ-05 immobilized microspheres and activated carbon microspheres with the same loose network structure was very illuminating to widen the type of porogen; Comparing with the embedding method, adsorption method didn't introduce other pollutants, which operation is simple and can provide an effective way for the resource utilization of YJ-05, finally choosing YJ-05 adsorption method to fix bacteria to repair the soil.