Modelling and Simulation of Biobutanol Fermentation by Clostridium saccharoperbutylacetonicum N1-4

Abstract

Biobutanol exhibits high octane number, non-hygroscopic, non-corrosive and can be mixed with gasoline without engine modification. Furthermore, the use of biobutanol as a fuel can reduce the negative impact of environmental due to the use of fossil-based fuel. Therefore, research on the development of biobutanol is still very much needed, including research on modelling and simulation of biobutanol production by fermentation. With modelling and simulation, we can predict various biobutanol production behaviour. This paper deals with the modelling and simulation of the production of biobutanol from glucose in batch bioreactor using Clostridium saccharoperbutylacetonicum N1-4. C. saccharoperbutylacetonicum N1-4 exhibits a good growth ability on simple or complex sugars, such as glucose, sucrose, or starch. This study concerned with the kinetics models of biobutanol production as developed by Shinto based on the C. acetobutylicum metabolic pathway which consists of the glycolysis, acidogenesis and solventogenesis pathways with several simplification of reactions. In this study, modelling was carried out by adapting the rate parameter value of k13 indicating the rate constant of cell death. The adapted models were applied to determine the effect of the initial concentration of glucose and organic acids on the production of butanol and compared to the experimental data from previous research. Model simulations were performed by using MATLAB® software. The butanol yield was affected by the initial glucose concentration. The highest butanol yield of 77% was obtained at a glucose concentration of 22 g/L. The simulation results exhibit that the biobutanol yield decreases when the glucose concentration is higher than 22 g/L. These results are consistent with previous experimental data. The simulation results also show the effect of the concentration of acetic acid in the fermentation medium and can be optimized. From the simulation results, the presence of 7.5 g/L acetic acid can increase the biobutanol production by 20%. However, previous experimental data showed that a concentration of 2.5 g/L acetic acid was preferred. The simulation results also show the effect of the addition of butyric acid and lactic acid on the production of biobutanol.