Journal des bioprocédés et des biotechniques

Kinetic Modeling and Optimization of a Batch Ethanol Fermentation Process

Abstract

Samuel C Oliveira, Romulo C Oliveira, Mariana V Tacin and Edwil AL Gattás

A simple mathematical model, taking into account substrate limitation and inhibition by both the product ethanol and the substrate, was proposed and used to interpret experimental data from a batch alcohol fermentation process, conducted at two different sets of initial concentrations of sugar and cells. A detailed sequence of mathematical model derivation and parameter estimation is presented. The temporal profiles of sugar, cell and ethanol concentrations in the culture medium were modeled by a set of ordinary differential equations, which were integrated numerically by the 4^th-order Runge-Kutta-Gill method. The model was validated by real laboratory fermentations and the accuracy of the model is acceptable. The agreement between the simulation and experimental results demonstrates that the model is sufficiently reliable for prediction of the dynamic behavior of the bioprocess. A study of process optimization by means of an approximate model, used to describe the dynamics of sugar consumption, revealed the need to employ a multi-objective approach, to maximize simultaneously the ethanol productivity, ethanol concentration and the conversion of sugars.