Kinetic modelling of ethanol production from oil palm trunk SAP during fermentation

• Main Author: Sultana, Sharmin
• Format: Thesis
• Language: English
• Published: 2019
• Subjects: Q Science (General); T Technology (General)
• Online Access: http://umpir.ump.edu.my/id/eprint/30035/1/Kinetic%20modelling%20of%20ethanol%20production%20from%20oil%20palm%20trunk%20SAP%20during%20fermentation.wm.pdf; http://umpir.ump.edu.my/id/eprint/30035/

The worldwide limited storage of fossil fuel and its bad impact on environment lead to the recent research towards biomass for biofuel. Malaysia is rich with plenty of biomass resources. Oil palm trunk (OPT) is a promising biomass source for bioethanol production. Fermentation is an essential process of biomass to ethanol conversion. An appropriate kinetic model will be a powerful tool to increase the efficiency and process optimization for ethanol fermentation using the OPT sap. The theoretical methods are more efficient and require low investment, but it is challenging to validate. A number of kinetic models have been proposed but none of these models observed the effect of most essential factors such as substrate limitation, substrate inhibition, product inhibition, and cell death simultaneously on temperature to produce ethanol from the OPT sap fermentation. We extended and improved the current mathematical model to explore the effect of temperature, initial cell concentration and cell death rate on the fermentation process. Several kinetic parameters were used to describe this phenomenon. A set of ordinary differential equations were used to modelled the profiles of sugar, cell and ethanol for the fermentation of OPT sap and the equations were solved by the 4th order Runge-Kutta method. There are two sets of simulation results presented in this study for Model I and II. Model I is a simple model which extends Oliviera’s model, where we studied the effect of cell death rate. Model II is more comprehensive and better than Model I, because it consists Leudeking-Piret relationship, Phisalaphong model and also Model I. Some significant characteristics are apprehended both of the models. As the temperature increased, the maximum specific cell growth rate decreased for both of the models. From the results, the suitable temperature for ethanol production from the OPT sap fermentation is 30C. The rate of sugar utilisation and ethanol production throughout fermentation process depend on the initial cell concentration. With the low initial cell concentration, the conversion rate was increased gradually but for the high initial cell concentration, sugar conversion to ethanol was augmented sharply and depleted after the short duration due to 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 II by means of rRMSE. This approach has enabled us to obtained a better predictive capabilities hence increasing our understanding of the mathematical model of the OPT sap fermentation.