High-titer ethanol production from simultaneous saccharification and fermentation using a continuous feeding system

• SSF process with a continuous feeding system was used at high-solids loading.
• An angle-type impeller affected the SSF process at high solid loadings.
• Prehydrolysis and the SSF process yielded 63–70 g/L ethanol.
• SSF with an angle impeller yielded 69.2 g/L ethanol (87.2% yield), after 56 h.

A high-solid loading of lignocellulosic biomass in hydrolysis and simultaneous saccharification and fermentation (SSF) processes would make biofuel production more economical. However, several bottlenecks are determined by biomass characteristics, such as absorptiveness. We investigated the enzymatic digestibility and fermentability of pretreated Miscanthus as a high-concentration biomass in an SSF process, using a continuous feeding system and a particular type of impeller. When prehydrolysis and SSF was performed with a 25% dry solid loading, containing 30 FPU/g cellulose, for 56 h, 63.4 ± 1.0 g/L ethanol was produced with a standard impeller, while 69.2 ± 1.6 g/L ethanol was produced with an angled-type of impeller. Ethanol was produced in a short time, and ethanol productivity was enhanced, by using the continuous feeding system and an impeller angled at 30°. These findings contribute to the development of a continuous-production process for obtaining bioethanol from lignocellulosic biomass.