Modified method combining in situ detoxification with simultaneous saccharification and cofermentation (SSCF) as a...

This paper reports an improved fermentation process that includes simultaneous saccharification, detoxification, and cofermentation as steps for producing bioethanol. Rice straw was first steam exploded (SE) or butanone solution exploded (BSE) and then cofermented with Saccharomyces cerevisiae and Candida shehatae. To overcome the inhibitors, the exploded rice straw was continuously and slowly introduced into a 10 L ventilated fermenter. When the fermentation conditions were set to 1.0% initial dry matter, 10% total dry matter, addition rate of 120 mg/min, total fermentation time of 234 h, and dose of 0.1% (NH4)2SO4, yields of 25.8 g/100 g of dry matter ethanol and 88% total sugar use were obtained for BSE rice straw. The ethanol yields were not significantly different between detoxified materials and non-detoxified materials. Most of the furfural, hydroxymethylfurfural (5-HMF), acetic acid, and butanone were removed during the fermentation of non-detoxified materials, and the sugar concentrations were very low. The in situ detoxification and fermentation was effective and inexpensive when the pre-detoxification of exploded materials and the pre-adaptation of strains steps were omitted.