A novel immobilized bioreactor based on CFD simulation for fuel ethanol production from corn

Abstract

This study evaluated the feasibility of ethanol production from corn in a surface immobilized bioreactor. The mass transfer of 50 L immobilized bioreactor was analyzed based on computational fluid dynamics (CFD) simulation. Compared to the traditional stirred fermenter, the surface immobilized fermenter system exhibited a relatively weak liquid velocity, but its flow field distribution was relatively uniform, which ensured an ideal interaction environment between cells and substrates. The difference of fermentation indexes between the two fermentation methods was then verified by ethanol fermentation using corn hydrolysate. It was found that the ethanol productivity (P) of immobilized cells was increased by 20.59 %, while the amount of corn consumed for one ton of ethanol was decreased by 5.90 %. To further enhance industrial application, the semi-continuous fermentation was adopted, the P and ethanol yield were increased by 30.88 % and 3.06 percentage points, respectively, compared to free-cell fermentation (FCF). This work demonstrated that the mass transfer issues associated with traditional immobilized-cell fermentation (ICF), such as embedding and chemical crosslinking, were resolved through bioreactor design and process optimization. Meanwhile, the surface immobilization technology showcased special advantages, including a broad spectrum of raw materials and strong process stability, indicating great industrial application potential in ethanol production.