Tuesday, May 1, 2007 - 8:20 AM

Biorefinery of corn cob: concept and practice in China

Yinbo Qu, Mingtian Zhu, Kai Liu, Jiacheng Shen, Xiaoming Bao, and Jianqiang Lin. State Key Laboratory of Microbial Technology, Shandong University, 27, Shanda-nan Road, Jinan, China

Corn cobs contain higher content of hemicellulose and have been used for xylose, xylitol, oligomer of xylose and furfural production. In Yucheng area of Shandong, China, several factories have already been established, which have capabilities of producing about 13,000 tons of xylose, 20,000 tons of xylitol, 10,000 tons of xylo-oligosaccharide and 5,000 tons of furfural annually. About 300,000 tons of corncobs were consumed per year by them, and more than 200,000 tons of waste cellulosic residues were discarded. The cellulose content of the residues increased to 55-60 % after the hemicellulose extraction by enzyme or acid.  It was found that these cellulosic residues can be hydrolyzed to glucose by cellulase, and then be fermented to ethanol by yeast very easily. The ethanol yield from the residue was more than 24 %, and the conversion of cellulose to ethanol can be more than 90 %. The cellulases can also be produced with increased activities using these cellulosic residues as main raw material in situ.
By combining of cellulase and ethanol production with xylose-related products production, the total production cost will be reduced, and the difficulties of xylose-to-ethanol fermentation will be warded off. The residues from ethanol fermentation contains more than 50 % of lignin and increased heating value, which can be used for electricity and steam production in situ too. A biorefinery with a production capacity of 10,000-ton cellulosic ethanol is constructing at Yucheng now.