Modeling of DBT Biodesulfurization by Resting Cells of Gordonia sp. WQ-01A Immobilized in Alginate Gel Beads in an Oil-water-immobilization System

Y. Peng and J. Wen

Abstract
In this study, the resting cells of Gordonia sp. WQ-01A, a DBT-desulfurizing strain, were immobilized by calcium alginate. Batch DBT biodesulfurization experiments using immobilized cells and n-dodecane as the oil phase were conducted in fermenter under varying operating conditions such as initial DBT concentration, bead loading and the oil phase volume fraction. When the initial DBT concentration is 0.5, 1 and 5 mmol L–1, the DBT concentration dropped almost to zero after t = 40, 60 and 100 hours, respectively. The influence of bead loading and the oil-phase volume fraction was small to the DBT biodesulfurization. Furthermore, a mathematical model was proposed to simulate the batch DBT biodesulfurization process in an oil-water-immobilization system, which took into account the internal and external mass transfer resistances of DBT and oxygen, and the intrinsic kinetics of bacteria. To validate this model, the comparison between the model simulations and the experimental measurements of DBT concentration profiles in the oil phase was carried out and the agreement is very good. In addition, the time and radius courses of DBT and oxygen concentrations within the alginate gel beads were reasonably predicted by the proposed model.

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Keywords
Dibenzothiophene (DBT), DBT biodesulfurization, alginate, oil-water-immobilization, modeling