Influence of the reactor shape on the kinetics of ethanol production in laboratory-scale batch fermentation tests carried out in unstirred vessels

Abstract

The influence of the shape of laboratory-scale unstirred reactors on the kinetics of ethanol production in batch ethanol fermentation was studied. Two reactors were used: a 1-L glass measuring cylinder and a 2-L Erlenmeyer flask. The volume of inoculated medium in each reactor was 1,000 mL. The above influence was affected by the ratio between the initial yeast cells concentration (X0: ∼7 g/L, ∼14 g/L, and ∼21 g/L, dry matter) and the initial glucose concentration (S0: ∼100 g/L, ∼150 g/L and ∼200 g/L). When X0/S0 increased from 0.038 to 0.219 the influence of the reactor shape decreased, and was not observed when X0/S0 = 0.22 to 0.24. The reactor shape practically did not affect the ethanol yield, the final yeast cells concentration and both the viability and the morphology of the cells in tests carried out at the same value of X0/S0.