The Screening Of Efficient Desulphurization Bacterium And Immobilized Application

This paper aiming at the pollution status of sulfur to oils，obtained five high efficientdesulfurization strains from the contaminated activated sludge by enrichment culture，colonymorphology was observed after dilution crossed separation. Two strains were isolated afterdetermination of the effect of desulfurization and carbon utilization experiments，named S-2and S-4. The software Design-Expert8.05was applied to the response surface optimizationexperiment. And the influence of three factors which were reaction time，concentration ofthiophene and concentration of microorganism was studied in the process of desulphurizationstrains degradation. For strain S-2, the optimum reaction conditions were as follows: reactiontime25.46h, concentration of thiophene1.01%, concentration of microorganism2.98%.Under these conditions, the maximum theoretic thiophene degradation rate was14.74%.Forstrain S-4, the optimum reaction conditions were reaction time36h, concentration ofthiophene1.07%, concentration of microorganism4.82%. Under these conditions, themaximum theoretic thiophene degradation rate was15.38%. USY zeolite was selected as theimmobilization carrier, and immobilized bacteria was prepared by adsorption method. Afterinvestigating the desulfurization single factors，response surface experiments to optimize theprocess conditions and parameters were designed. Thus,we could study the desulfurizationperformance of the immobilized bacteria.The results were as follows:for strain S-2, theoptimum reaction conditions were reaction time29.17h, concentration of thiophene1.01%,microorganism10.25mL/50mL. Under these conditions, the maximum theoretic thiophenedegradation rate was23.50%. For strain S-4, the optimum reaction conditions were reactiontime27.17h, concentration of thiophene1.04%, microorganism10.25mL/50mL. Under theseconditions, the maximum theoretic thiophene degradation rate was25.93%.The comparativeresults between immobilized bacteria and free bacteria showed that the immobilized bacteria’sdegradation rate of thiophene was better than that of free bacteria.Immobilized bacteria S-4was selected to simulate biodesulfurization. The optimum reaction conditions were determined as follows: flow velocity1.31×10-5m/s, concentration of thiophene1.08%,concentration of microorganism6.20g/20mL. Under these conditions, the maximum theoreticthiophene degradation rate was23.88%.The reactor had a stable performance in cintinuousoperation.