Capture of carbon dioxide from ethanol fermentation by liquid absorption for use in biological production of succinic acid

Authors: Nghiem, Nhuan; Senske, Gerard

Submitted to: Applied Biochemistry and Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/10/2014
Publication Date: 12/2/2014
Publication URL: http://handle.nal.usda.gov/10113/60326
Citation: Nghiem, N.P., Senske, G.E. 2014. Capture of carbon dioxide from ethanol fermentation by liquid absorption for use in biological production of succinic acid. Applied Biochemistry and Biotechnology. 175:2104-2113.

Interpretive Summary: Carbon dioxide is a gaseous by-product of ethanol fermentation. Capture or use of this gas for production of industrial chemicals will not only reduce the release of this green-house gas into the atmosphere but also create opportunities for value-added co-products of ethanol. Previously it was shown that the gas produced in an ethanol fermentor using either corn or barley as feedstock could be sparged directly into an adjacent fermentor to provide the CO2 required for succinic acid production. In the present investigation it has been demonstrated that the CO2 produced in a corn ethanol fermentor could be absorbed in a base solution and the resultant carbonate solution used both for pH control and supply of the CO2 requirement in succinic acid fermentation. In a commercial setting, capture of CO2 in liquid form will allow transportation of the carbonate solutions to locations not in the immediate vicinity of the ethanol plant and the excess carbonate salts also can be recovered as value-added products.

Technical Abstract: Previously it was shown that the gas produced in an ethanol fermentor using either corn or barley as feedstock could be sparged directly into an adjacent fermentor using Escherichia coli AFP184 to provide the CO2 required for succinic acid production. In the present investigation it has been demonstrated that the CO2 produced in a corn ethanol fermentor could be absorbed in a base solution and the resultant carbonate solution used both for pH control and supply of the CO2 requirement in succinic acid fermentation. Thus, the CO2 produced in a 5-liter corn mash containing 30 wt% total solids was absorbed in a packed column containing two liters of one of the following: 5 M NaOH, 5 M KOH, or 15 wt% NH4OH, and the resultant carbonate solutions were used for pH control and as a carbon source in a succinic acid fermentor. The results obtained indicated no significant differences between succinic acid production in these experiments and when 2.5 M solutions of Na2CO3, K2CO3 and (NH4)2CO3 prepared with commercial products were used. In a commercial setting, capture of CO2 in liquid form will allow transportation of the carbonate solutions to locations not in the immediate vicinity of the ethanol plant and the excess carbonate salts also can be recovered as value-added products.