S teady State Performance of a Bioreactor for Production of near Zero Sulfur Diesel (NZSD) and Bio-surfactant

Abstrac t—Kinetics of biodesulfurization of hydrotreated diesel using Rhodococcus sp has been studied with special reference to removal of organo-sulfur compounds in diesel and production of 2-hydroxy biphenyl. The identification of 2-HBP in treated diesel has been made using HPLC,FTIR and GCMS .The sulfur concentration of feed diesel was in the range of 200-540 mg/L. Aqueous phase to diesel ratios were varied in the range of 9:1 to1:9. The optimum ratio was found to be 1:4 and the maximum conversion of sulfur was determined to be 95%. The values of Monod kinetic parameters namely, µ m ax, maximum specific gro wth rate and Ks, saturation constant of the microbial growth and Yield coefficient of surfactant have been measured to be 0.096h -1 , 71mg/L , and 17 µmol/g dry cell weights respectively by conducting batch type experiments. A continuous chemostat was studied using different hydrodynamic and physico-chemical parameters like dilution rate, initial concentration of organo-sulfur compounds in diesel, stirring rate and aeration rate. Surfactant part was characterized by determination of surface tension (Ring method), E24, TLC, HPLC and GC-MS. The interfacial tension of the supernatant fermented by Rhodococcus sp decreased from 28 dynes/cm to 9 dynes/cm.The surface tension of aqueous nutrient phase and diesel was observed to decrease from 71 dynes/cm to 30 dynes/cm and to 20 dynes/cm from 30dynes/cm respectively. Values of emulsification index (E24) were determined to vary from 18 to 58 over the growth period of 2 to 48 hours in the chemostat. The critical miceller concentration was found to be 200mg/L. The simulated data have been compared with the experimental ones to validate the model.

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