Submitted to: American Institute of Chemical Engineers Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: November 12, 2004
Publication Date: November 12, 2004
Citation: Qureshi, N., Ezeji, T.C., Blaschek, H.P., Cotta, M.A. 2004. A novel biological process to convert renewable biomass to acetone and butanol (AB) [abstract]. American Institute of Chemical Engineers. Paper No. 29d. Technical Abstract: Butanol is an industrially important fuel and chemical that can be produced from renewable agricultural crops and residues by fermentation. Unfortunately, this fermentation suffers from butanol toxicity, resulting in accumulation of less than 20 gL-1 butanol in batch reactors. This limits use of dilute sugar solutions, usually to less than 60 gL-1, and results in uneconomic recovery of butanol by distillation. Furthermore, butanol recovery by distillation is complicated by its higher boiling point (118 deg C) than water. In order to solve butanol toxicity (to the culture) and recovery problems and make butanol fermentation a commercially viable process, gas stripping, a novel technique to separate butanol was applied to this fermentation. For this purpose, fermentation gases (CO2 & H2: produced in this fermentation) were used to remove butanol from the reactor simultaneously as AB was produced. The simultaneous recovery of butanol (integrated process) relieved toxicity, improved reactor productivity and yield, and resulted in a concentrated product stream for further separation and purification. The yield was improved due to efficient utilization of acetic and butyric acids that are reaction intermediates to acetone and butanol. Using gas stripping as a means to remove butanol from the fermentation broth, three efficient fermentation processes (batch, fed-batch, and continuous) were developed. In order to reduce the overall energy requirement for butanol production, concentrated sugar solutions (250-500 gL-1) were used, as compared to 60 gL-1 applied in non-integrated batch fermentations. As a result of these novel developments, further process scale-up is being attempted to commercialize the biological conversion of agricultural biomass to butanol. These studies were performed employing Clostridium beijerinckii BA101 to produce AB.