Gas stripping technique applied to Brazilian raw material: diluted sugarcane molasses

Brazilian bioethanol is considered one of the most attractive alternatives for renewable fuels produced in the world. Despite a lot of research is devoted to the production of second generation ethanol from sugarcane, there is a room for improvements in the traditional production of first generation ethanol, mainly because first generation production still presents itself a high energetic consumption. Several techniques that couple fermentation to a continuous process removal can greatly decrease this energy requirement because it  can provides higher sugar concentration in fermentation step, which, in fact, decreases the amount of water added to the process. Thus, in this study, the technique of in situ Gas Stripping Fermentation (GSF) which can remove volatiles continuously during the fermentation process was evaluated. GSF is a simple and inexpensive technique which was assessed experimentally to moderate concentrations of sugar in the feed of lab scale process.  A reactor equipped with an impeller, stirring blades and temperature control was coupled to a condenser with high heat transfer area in order to condensate almost all ethanol stripped from the broth. This work highlighted an experimental trial using local sugarcane diluted molasses and microorganism (S. cerevisiae) as a possibility for further applications on the industry. A mechanistic model was proposed and fitted for an experimental data set. The model could satisfactory predict experiments outside the range of sugar initially studied. Estimation parameters values showed good results compared to those from literature.