Modeling and simulation of serial biorreactors for obtaining ethanol using the Tosetto equation

Abstract

In this work, a process for transient ethanol production was simulated with bioreactors arranged in series. The simulation was performed in the OCTAVE software, solving a system of nine non-linear differential equations, using the numerical method of Runge-Kutta. With this simulation it was possible to verify the effectiveness of the use of a bioreactor in the production of ethanol, considering the boundary conditions and establishing the characteristics for a possible optimization of the conversion and productivity in the process. From the results of the simulation, it was observed that the Tosetto Equation is suitable for modeling the process of obtaining ethanol in bioreactors and consistent with published works. The concentration of cells increased significantly, in three hours of process it entered a permanent regime, which is compatible with the theory of cell growth. Regarding the concentration of the substrate, it was observed that it decreased significantly up to 4 hours and after 10 hours there is a small increase in concentration, indicating inhibition by the substrate. The concentration of the ethanol product increased by ten percent with each passage through reactors 1, 2 and 3 until reaching a concentration of ethanol of eighty grams per liter in a transient regime. The simulation carried out in three stages makes the process more efficient instead of using only one bioreactor.