Recovery of butanol from Clostridium beijerinckii P260 fermentation broth by supercritical CO

Authors: Qureshi, Nasib; Eller, Fred

Submitted to: Journal of Chemical Technology & Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/13/2017
Publication Date: 4/1/2018
Citation: Qureshi, N., Eller, F.J. 2018. Recovery of butanol from Clostridium beijerinckii P260 fermentation broth by supercritical CO. Journal of Chemical Technology & Biotechnology. 93(4)1206-1212. https://doi.org/10.1002/jctb.5482.
DOI: https://doi.org/10.1002/jctb.5482

Interpretive Summary: In these studies a technique to recover butanol biofuel from fermentation mixture was developed. Butanol, a superior biofuel than ethanol, has excellent gasoline blend properties. This biofuel can be produced from corn or lignocellulosic residues of which the latter is preferred due to its sustainability in nature and much lower prices than corn. Recently we have been successful with the use of cellulosic biomass for this process. Another problem with the production of this fuel is its costly recovery from the fermentation mixture by distillation. For this reason we have developed a technique to recover it. In this process, carbon dioxide gas is compressed to a high pressure until it becomes liquid, which is then used to extract butanol from the aqueous mixture. This new technique produces highly concentrated butanol from low amounts present in the fermentation mixture. As an added benefit of this technique, nutrients in the extracted mixture are not removed and the mixture can be recycled, which further reduces the use of process water. These developments will make butanol production from agricultural residues economically attractive. This technology will benefit U.S. farmers, butanol and automotive industry, and the public.

Technical Abstract: Butanol is a superior biofuel to ethanol because of its blend properties and higher energy density. However, its recovery by distillation from the fermentation broth is energy intensive. For this reason, we studied butanol recovery by supercritical CO2 extraction from simulated and actual fermentation broths. Recovery of butanol by this technique has numerous advantages including being environmentally favorable, avoiding use of costly chemicals or membranes, and compatible with the microbial culture. For the model solution extraction process, feed contained 7.00, 12.00, and 1.00 gL-1 acetone, butanol, ethanol (ABE), respectively, to mimic the actual concentrations obtained in the fermentation broth. In the extract phase, butanol concentration that was obtained ranged from 460.4 to 573.2 gL-1 with butanol selectivities ranging from 128 to 204.8. ABE recovery was also successfully demonstrated using actual fermentation broth of C. beijerinckii P260. Supercritical CO2 was successfully used for recovery of all three (ABE) components. Fermentation broth raffinate (feed depleted in ABE after recovery) was also reused for a second fermentation thus allowing process water recycle.