3-29: Simultaneous bioconversion of Barley Straw to butanol and product recovery: Use of concentrated sugar solution and process integration

As a result of increased gasoline prices, we focused on the production of butanol which contains more energy than ethanol on per gallon (or kg) basis from cellulosic agricultural biomass such as wheat straw using two different systems: i) separate hydrolysis, fermentation, and recovery (SHFR), and ii) simultaneous saccharification, fermentation and recovery (SSFR). Furthermore, use of barley straw and corn stover hydrolyzates was investigated which proved to be more difficult to support cell growth and fermentation as they were toxic to the culture. All the investigated feedstocks proved to be different in terms of their pretreatment requirements, digestibility using enzymes, and fermentation characteristics. In these investigations barley straw hydrolyzate was fermented and product was removed simultaneously. Barley straw was pretreated with dilute sulfuric acid at 121 ^oC for 1 h followed by hydrolysis using enzymes. The hydrolyzate was supplemented with additional sugar to raise sugar level in the reactor followed by simultaneous fermentation to butanol and recovery (SHFR). This way the process was integrated and concentrated barley straw hydrolyzate was successfully fermented using Clostridium beijerinckii P260 which resulted in utilization of 100% sugars present in the reactor.