ETHANOL-PRODUCTION BY WHOLE CELL IMMOBILIZATION USING LIGNOCELLULOSIC MATERIALS AS SOLID MATRIX

Amongst four carriers used, rice-straw was found to be superior in terms of ethanol production. The maximum productivity (17.84 gl-1 h-1) corresponded to a dilution rate of 0.39 h-1, the ethanol concentration being 45.80 gl-1. A multistage rhomboidal bioreactor was found to partially overcome the disruption effect caused by the generation of a large volume of carbon dioxide in the column. Increases in productivity of about 12.55% and 3.6%, respectively, were achieved using rhomboidal and tapered bioreactors as compared to the cylindrical bioreactor. It was observed that the generation time of cells, in both the immobilized and free states, was around 2.5 h. The ethanol yield (Y(p/s)) in the lower part of the reactor was less in comparison with other zones, where the substrate utilization efficiency was relatively higher.