Evaluation of continuous fermentation coupled with microfiltration and cells recycles for bioethanol production

In the last decades many renewable and considered sustained energy sources as solar, wind, hydro, wave have been available, but among them, biomass is potentially the most promising one to mobility purposes. That is the case of the bioethanol that in Brazil is produced from sugar cane. However, it is considered in many large scale plants (around two millions liter/day) that the fermentation step in bioethanol production process is usually subject to inhibition by temperature, substrate, product and environmental contamination, especially in industrial process. This is one of the reasons that many large scale mills for bioethanol production make use of batch fermentation. Furthermore, continuous processes are known to exhibit higher yield and productivity compared to the discontinuous process. One alternative process that is gaining acceptance is the continuous fermentation coupled with microfiltration membrane for recycling the biomass and it is expected that this fermentation conception may lead to higher yield and productivity compared to the discontinuous process. Besides, the microfiltration membranes are suitable for the continuous separation of the broth and the biomass from the wine of fermentation, as to provide a sterile environment during fermentation. Thus, in this work, it is shown the simulation, carried out in Aspen Plus; of the continuous fermentation of glucose to ethanol with yeast recycle using a microfiltration membrane. This process provides suitable wine conditions for ethanol purification and dehydration by known methods such as distillation, pervaporation, liquid-liquid extraction, and appears to have a good potential to be tested in industrial environment.