Effect of Sodium Alginate Concentration on Size of Yeast Immobilized Particle and on Production of Bio-ethanol in a Packed-Bed Fermenter

Abstract

Biofuels are important because they replace the petroleum fuels or fossil fuels and especially ethanol and butanol contribute greatly to the mitigation of greenhouse gases emission, provide clean and sustainable energy source and reduce the consumption of crude oil. Current ethanol production processes using agricultural crops such as sugarcane and corn are well known, i.e., biochemical pathway and thermo-chemical pathway. However, in the biochemical pathway, the reactors used for fermentation have to be improved from a classical well-mixed reactor such as batch fermenter and fed-batch fermentor to the continuous reactors due to the following reasons, i.e., product inhibition and wash out, etc. An attempt has been made to improve the reactor design using continuous packed-bed reactor with baker’s yeast as microorganism and this was immobilized in calcium alginate beads (particles). In the present study, we have conducted experiments to identify the suitable bead size and suitable concentrations of sodium and calcium alginate solutions for better sugar conversion or more ethanol yield in batch reactor. The same beads are used for continuous packed-bed study. The results are compared. The continuous packed-bed reactor gave better conversions with retention time of 5 h.