Improvement of Product Quality by pH Control and Behaviors of Organic Impurities in the Distillation and Refining Process of A Bioethanol Plant from Waste Wood

The quality standard for the fuel ethanol for gasohol, JIS K2190, was established in 2011 in Japan. In the bioethanol production process the product should be highly purified because the fermentation broth contains a lot of impurities. In this study, the behaviors of the ethanol quality and impurities in the distillation and refining process in a commercial bioethanol plant from waste wood were studied. The product quality was not stable due to the change in the quality of the each fermentation broth and it was shown that acidity and sulfur concentration should be improved. The pH control in re flux solution was attempted to improve the quality. By this pH control, acidity, electrical conductivity, water concentration, and sulfur concentration of product were improved. The behaviors of organic impurities were also studied. The concentration of the organic impurities was 5.0 perpendicular to 2.0 g/L and the main components of the impurity were propan-1-ol, 2-butanol, and acetal. It was shown that the fusel oil removal from distillation process was effective to reduce the concentration of organic impurities.