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۱Behavior of the growing cells of Ralstonia eutropha in biodesulfurization of dibenzothiophene
اطلاعات انتشار: چهارمین همایش علمی مهندسی فرآیند، سال
تعداد صفحات: ۶
The new regulations to lower sulfur content in fossil fuels require new economic and efficient methods for desulfurization of recalcitrant organic sulfur. Hydrodesulfurization (HDS) of such compounds is very costly and requires high operating temperature and pressure. Biodesulfurization (BDS) is non–invasive approach that can specifically remove sulfur from refractory hydrocarbons under mild conditions and it can be potentially used in industrial desulfurization. Biodesulfurization of dibenzothiophene (DBT) by growing cells of Ralstonia eutropha in aqueous reaction system was investigated in the present study. DBT and glucose, respectively used as the sole source of sulfur and carbon for growth of R. eutropha. The effect of different initial concentrations of DBT (15 and 20 ppm) with a constant level of glucose at 10 g\L on the R. eutropha growth and its DBT desulfurization capability and pH variation was studied. Growth behavior of the bacterial cells was generally the same and no significant differences in growth rate were observed in which different initial concentrations of DBT were used. During the first eight hours of cell growth, the pH of medium was decreased. The desulfurization activity of the cells was measured with use of Gibb’s reagent and Cells cultivated in the medium containing 15 ppm of DBT showed higher desulfurization activity<\div>

۲The pH of the reaction mixture affects bio–production of lactic acid by loofa immobilized Rhizopus oryzae PTCC 5263
اطلاعات انتشار: سومین کنفرانس بین المللی علوم و مهندسی، سال
تعداد صفحات: ۶
Lactic acid production by Rhizopus oryzae PTCC 5263 was evaluated in the present study and the strain’s ability in production of this organic acid was carried out at various pH ranges of the culture media. Lactic acid production was optimized upon the fermentation being controlled at pH 4.5 by adding calcium carbonate slurry and maximum lactic acid concentration was 41 g\l. Additionally, the production of lactic acid by loofa immobilized R. oryzae was compared with free cells and the maximum productivity was obtained during second 24 h of fermentation for immobilized cells (1.82 g\l.h) and final production and yield of lactic acid were 54.06g\l and 45.6%, respectively. Therefore, the immobilization of R. oryzae in loofa sponge can sustain stable morphology control in filamentous fungal fermentation and prevent the oxygen and nutrient limitations. Thus, cell immobilization via adsorption in the bare pieces of loofa sponge is a suitable technique in lactic acid production<\div>
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