Bubble column bioreactor design and evaluation for bioethanol production using simultaneous saccharification and fermentation strategy from hydrothermally pretreated lignocellulosic biomass

Abstract

Lignocellulosic biomass serves as an alternative renewable feed stock for the production of bioethanol using biochemical platform. Ethanol yield can be improved by adopting strategies such as simultaneous enzymatic saccharification and fermentation (SSF) using pneumatic bioreactors, robust yeast and biomass pretreated with hydrothermal process. In the present study two strains of Saccharomyces cerevisiae: flocculant (CA11) and non- flocculant (PE-2) were evaluated to grow at temperature. The S. cerevisiae PE-2 was selected for fermentation at 40 ºC for ethanol production and a bubble column bioreactor (BCB) of 3 L was designed and operated for bioethanol production. Hydrothermally pretreated (180 ºC for 30 min) wheat straw rich in cellulose fraction (49.83 g/100 of biomass) with a severity factor (log [Ro] = 4.04) was used as the substrate for SSF strategy for bioethanol production using in a three-phase (gas–liquid–solid) bubble column bioreactor. The ethanol concentration was 9.31 g/L using 10% (w/v) of pretreated solid loading and 15 FPU/g substrate of enzyme loading in a BCB. The robust yeasts, pneumatic bioreactors and hydrothermal pretreatment are a great alternative in the production of biofuels at an industrial level in terms of second generation biorefineries.