This paper extended and improved the current mathematical model for the batch fermentation process. By varying the initial cell concentration, the model predicted the profile of cell growth and ethanol production throughout the fermentation process. The kinetic models take into account the following factors which are substrate limitation, substrate inhibition, product inhibition, and cell death simultaneously for the production of ethanol from the OPT sap. The mathematical model was formulated using a set of ordinary differential equations to describe the profiles of sugar, cell and ethanol during the fermentation process. The set of equations were solved numerically by using the 4th order Runge-Kutta method. The result showed that the rate of sugar utilization and ethanol production are depended on the initial cell concentration. For low initial cell concentration, the conversion rate was increased gradually. On the other hand, for high initial cell concentration, sugar conversion to ethanol was augmented sharply and depleted after a short duration due to the access of the ethanol, which might inhibit the cell growth. The combined consideration of the substrate limitation and inhibition, growth and non-growth associated product formation, product inhibition and cell death rate increased the accuracy of the model by means of rRMSE. The proposed model has better predictive capabilities. This approach has increased our understanding of the theory behind the OPT sap fermentation.
Volume 11 | 12-Special Issue