A continuous process that promises to slash the cost of making bioethanol

A compact, inexpensive and energy-saving continuous process to make bioethanol is being developed by professor Yoshio Katakura at Kansai University (Osaka; microbial.life-bio.kansai-u.ac.jp), in collaboration with the Kinki Bio-industry Development Organization (Osaka), Kansai Chemical Engineering Co. (Amagasaki), and Akita National College of Industry (Akita, all Japan). The so-called CCSSF process (consolidated, continuous, solid-state fermentation) uses simple equipment that can easily be installed next to a biomass-treatment facility. In the CCSSF system (diagram), a slurry (50 wt.% water) of biomass, diastatic enzymes and yeast is continuously fermented in a rotating drum. The ethanol vapor generated in the headspace of the drum is continuously removed and condensed as a 30–40% aqueous solution. In laboratory trials, a 93% ethanol yield has been observed (87 g ethanol from 165 g of starch). The researchers have also demonstrated that cellulose-based raw materials, such as cotton fibers and recycled waste-paper, can be used as raw materials. Unlike conventional processes, CCSSF does not require separate units for performing saccharification and fermentation, and only compostable residues are produced, thus eliminating the…