Bio-desulfurization of model organosulfur compounds, namely alkylated dibenzothiophene (DBT) and diesel oil was conducted in a laboratory scale fermenter using pure and isolated bacterial strains namely, Rhodococcus sp. (NCIM-2891) and Rhodococcus sp. JUBDS1 respectively. The diesel used as the feedstock was previously hydrodesulfurized up to a total sulfur content of 300-500 ppm. The Sulphur concentration of product stream of diesel from the process lies in the range of 10-15 ppm. Alkylated dibenzothiophenes were used in pure forms. During the study of chemostat in batch mode the initial substrate concentration of organosulfur compounds, the sulfur concentration in diesel, the stirring speed, temperature, oil to aqueous phase ratio, etc., were varied as parameters. The intrinsic kinetic parameters of bacterial growth like maximum specific growth, mmax, half saturation constant, and KS were determined by carrying out experiments in Erlenmeyer flasks using suitable medium and subsequent non-linear regression analysis. A mathematical model showing the transient behavior of chemostat was developed. Simulated data were compared with the experimental findings to validate the model developed.
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