Analysis of a Model for Ethanol Production through Continuous Fermentation: Ethanol Productivity

Abstract

We investigate a model for the production of ethanol through continuous fermentation using Saccharomyces cerevisiae in a single reactor and cascades of up to five reactors. Using path-following methods we investigate how the ethanol productivity varies with the residence time in each reactor of the cascade. With a substrate feed concentration of 160 g/l we find the optimal productivity is 3.80 g/l/h, 5.08 g/l/h, and 5.18 g/l/h in a single reactor, a double reactor cascade and a triple reactor cascade respectively. For the case of a cascade containing reactors of equal size we investigate reactor configurations of up to five reactors and find that the maximum productivity is obtained in a cascade containing three reactors. Disciplines Physical Sciences and Mathematics Publication DetailsSidhu, H. AbstractWe investigate a model for the production of ethanol through continuous fermentation using Saccharomyces cerevisiae in a single reactor and cascades of up to five reactors. Using path-following methods we investigate how the ethanol productivity varies with the residence time in each reactor of the cascade. With a substrate feed concentration of 160 g/l we find the optimal productivity is 3.80 g/l/h, 5.08 g/l/h, and 5.18 g/l/h in a single reactor, a double reactor cascade and a triple reactor cascade respectively. For the case of a cascade containing reactors of equal size we investigate reactor configurations of up to five reactors and find that the maximum productivity is obtained in a cascade containing three reactors.

Structured Mathematical Modeling, Bifurcation, and Simulation for the Bioethanol Fermentation Process Using Zymomonas mobilis

“…The rate of substrate consumption based on the maintenance model is given below r normals = C xv μ normalv Y xx + m normals C xnv The first term represents the growth rate of the viable microorganisms, while the second term represents the maintenance of the nonviable cells. From experimental observations of the production of ethanol using Z. mobiliz , , a mathematical model can be proposed where substrate is consumed in terms of ethanol as a product and energy by living cells at the rate of μ v .…”

“…For example, carbon monoxide, which is more harmful than carbon dioxide, emissions from combustion of ethanol are reduced by nearly 30% as the U.S. EPA showed due to the large oxygen content of ethanol. 1 Recently, many countries such as Brazil, Germany, the United States, and France have been producing and using ethanol as a fuel or blending it with gasoline at around 21% concentration. In Brazil, for instance, ethanol is used as a complete fuel in about one-half of all cars and as an additive with about 20% to gasoline.…”

“…In Brazil, for instance, ethanol is used as a complete fuel in about one-half of all cars and as an additive with about 20% to gasoline. 1 One of the main microorganisms used for production of bioethanol more efficiently than yeast is Zymomonas mobiliz. It is characterized by a higher ethanol production rate and yield and an ability to resist the high substrate and ethanol concentrations.…”

“…In addition, ethanol is a biodegradable fuel and does not produce unhealthy emissions like gasoline and other classical fuels and can be produced from renewable raw materials (RRMs) such as lignoceluolisic biomass. For example, carbon monoxide, which is more harmful than carbon dioxide, emissions from combustion of ethanol are reduced by nearly 30% as the U.S. EPA showed due to the large oxygen content of ethanol . Recently, many countries such as Brazil, Germany, the United States, and France have been producing and using ethanol as a fuel or blending it with gasoline at around 21% concentration.…”

“…Recently, many countries such as Brazil, Germany, the United States, and France have been producing and using ethanol as a fuel or blending it with gasoline at around 21% concentration. In Brazil, for instance, ethanol is used as a complete fuel in about one-half of all cars and as an additive with about 20% to gasoline …”