FEASIBILITY OF INSITU GAS STRIPPING FOR CONTINUOUS ACETONE-BUTANOL FERMENTATION BY CLOSTRIDIUM-ACETOBUTYLICUM

This work is a first attempt to study gas stripping for the in situ removal of butanol and acetone from continuous fermentation broths. The effect of sparging gas flowrate and dilution rate on the continuous culture of alginate-immobilized Clostridium acetobutylicum was studied. Solvent productivity was found to increase with increase in sparging gas flowrate up to 40 l(gas)/l-h, and then decreased as the gas flowrate increased further. A dilution rate of 0.07 h-1 was found to maximize volumetric solvent productivity (0.58 g/l-h), while the maximum specific productivity of 0.27 g/g-h occurred at 0. 12 h-1. A considerable improvement in solvent productivity and yield was obtained in the present work in comparison with batch fermentation results reported in the literature. However, the maximum productivity obtained in this work was still less than some values reported in the literature for continuous culture. In situ solvent stripping was found to keep the butanol concentration below toxic levels but was not suitable for complete removal of solvents from the broth.