Breeding Of A Desulfurization Strain And Study On Performance Of Dibenthiophene Biodesulfurization By The Strain

Biodesulfurization (BDS) is a newly high developing and environmentally benign biotechnology. BDS, in which anaerobic bacteria or aerobic bacteria are used in the selective removal of sulfur from petroleum and its distillates, is C-S-band-targeted but C-C-band-targeted fashion so that it can keep the caloric value of fuel. BDS technology has many advantages, such as easy manipulation, low-SO₂ emission and energy consumption, low cost and so on.DBT is considered as a model compound for BDS.The author isolated the bacterium H-412 which is capable of desulfurizing DBT as its sole sulfur source from soil which was polluted by petrol. HPLC shows that H-412 can remove sulfur from DBT, yielding 2-HBP through 4S pathway. The morphologic and taxonomic properties of the strain were investigated, and the strain belonged to Rhodococcus sp. according to Bergey's Manual of Determinative Bacteriology. The primary studies are as follows:Some factors as carbon source, nitrogen source, temperature and initial pH, affecting the growth of the strain and the production of 2HBP were studied. The optimum desulfurization ratio of H-412 90.75% could be obtained under the condition of 10 g/L glucose, 20 mL/L ethanol, 2 g/L NH4Cl, 30oC, and the initial pH=7.5. Based on the optimal cultivation, product inhibition kinetic models on the strain were set up. With computer simulating, the kinetic parameters of the strain can be confirmed. The experiment results showed that two models could describe the growth of the strain and the product 2-HBP very well.Elementary research on biodesulfurization of model system has been studied. Firstly, the capability of immobilized cells with the different carriers was studied, and the sodium alginate as the carrier was confirmed. The best conditions of immobilization are as follows: The experiment results indicated that the immobilized cell had the optimum desulfurization effect under the conditions of 4oC 0.1mmol/L CaCl₂ solution as cross-linking agent, 3 % SA as carrier, 1 % diatomite as additive, the ratio of sodium alginate (mL) to cell (g) being 20. Compared to free bacteria immobilized cell was able to endure higher temperature and adapt to wide range of pH. The experiment results also indicated that the immobilized cell had the optimum...