Tuesday, May 3, 2011
Research is being conducted world-wide toward the development of new technologies for liquid fuels production from renewable resources. In this context, production of bioethanol from biomass is one way for reducing both, consumption of crude oil and environmental pollution, becoming an important alternative for attaining a sustainable development. Currently, ethanol is produced by fermentation of sugars extracted from various crops such as sugar cane, corn and sugar beet. The competitiveness between ethanol and fossil fuels in the fuel market is ever higher because of the continuous technological progress. However, for an effective and efficient operation of the fermentation process, the kinetic characteristics of cell growth and ethanol production are required. For this purpose, various kinetic models associated with key parameters for ethanol fermentation have been proposed, taking into account parameters such as product yield, microorganism growth velocity, cell death rate, temperature; and inhibition by product, substrate and biomass concentration.
In this work, the fermentation kinetic model was fitted to the experimental data from literature to predict the behaviour of the fermentation process. The kinetic parameters were described as a function of temperature and were estimated using optimization techniques such as genetic algorithms and Levenberg Maquartd. The cell inhibition presents problems in the processes of fermentation for ethanol production, studies related to the feed shows improvements in the production. The cell inhibition was evaluated by variations of distributed feeding in continuous rectors. The model was used to study the influence of temperature and initial substrate concentration on ethanol production.