Abstract
In making alternative fuels from biomass feedstocks, the production of butyric acid is a key intermediate in the two-step production of butanol. The fermentation of glucose via Clostridium tyrobutyricum to butyric acid produces undesirable byproducts, including lactic acid and acetic acid, which significantly affect the butyric acid yield and productivity. This paper focuses on the production of butyric acid using Clostridium tyrobutyricum in a partial cell recycle mode to improve fermenter yield and productivity. Experiments with fermentation in batch, continuous culture and continuous culture with partial cell recycle by ultrafiltration were conducted. The results show that a continuous fermentation can be sustained for more than 120 days, which is the first reported long-term production of butyric acid in a continuous operation. Further, the results also show that partial cell recycle via membrane ultrafiltration has a great influence on the selectivity and productivity of butyric acid, with an increase in selectivity from ≈9% to 95% butyric acid with productivities as high as 1.13 g/Lh. Continuous fermentation with low dilution rate and high cell recycle ratio has been found to be desirable for optimum productivity and selectivity toward butyric acid and a comprehensive model explaining this phenomenon is given.
Highlights
Butyric acid is an organic acid produced via fermentation that is used in perfumes, as a food additive, and as an intermediate in alternative fuels [1]
A higher glucose concentration generally resulted in higher butyric acid selectivity
This indicates butyric acid selectivity is higher when the cell growth rate slows and a high glucose concentration would extend this time in the stationary phase and increase the overall butyric acid selectivity of the fermentation
Summary
Butyric acid is an organic acid produced via fermentation that is used in perfumes, as a food additive, and as an intermediate in alternative fuels [1]. Butyric acid production is the first step in a two-step fermentation route to produce butanol [2]. There is a renewed interest in butanol production from biomass and agricultural waste for sustainability, energy independence and reduction of dependence on foreign oil. The liquid fuels of primary focus from biomass to date have been bioethanol and biodiesel, the DOE Roadmap has identified butanol as a second generation biofuel [3]. Butanol is a potential gasoline substitute or additive which can favorably compete with or complement bioethanol manufacture. Several technical and economic challenges remain in commercial butanol production, including many of the challenges addressed by Ramey [2]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
