Simultaneous saccharification and continuous fermentation of sludge-containing mash for bioethanol production by Saccharomyces cerevisiae CHFY0321

A continuous process was employed to improve the volumetric productivity of bioethanol production from cassava mash containing sludge and to simplify the process of ethanol production from cassava. After raw cassava powder was liquefied, it was used directly in a continuous process without sludge filtration or saccharification. A fermentor consisting of four linked stirrer tanks was used for simultaneous saccharification and continuous fermentation (SSCF). Although the mash contained sludge, continuous fermentation was successfully achieved. We chose the dilution rate on the basis of the maximum saccharification time; the highest volumetric productivity and ethanol yield were observed at a dilution rate of 0.028 h−1. The volumetric productivity, final ethanol concentration, and % of theoretical ethanol yield were 2.41 g/L h, 86.1 g/L, and 91%, respectively. This SSCF process using the self-flocculating yeast Saccharomyces cerevisiae CHFY0321 illustrates the possibility of realizing cost-effective bioethanol production by eliminating additional saccharification and filtration processes. In addition, flocculent CHFY0321, which our group developed, showed excellent fermentation results under continuous ethanol production.

• Cassava was used directly in a continuous process without sludge filtration or saccharification.
• Continuous fermentation with the mash contained sludge was successfully achieved.
• SSCF of CHFY0321 illustrates the possibility of realizing cost-effective bioethanol production. Flocculent CHFY0321 showed excellent fermentation results.