Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2021 Aug 30:9:725578.
doi: 10.3389/fbioe.2021.725578. eCollection 2021.

A Downstream Processing Cascade for Separation of Caproic and Caprylic Acid from Maize Silage-Based Fermentation Broth

Maria Braune  1 , Bomin Yuan  1 , Heike Sträuber  2 , Stewart Charles McDowall  1 , Roy Nitzsche  1 , Arne Gröngröft  1
Affiliations

A Downstream Processing Cascade for Separation of Caproic and Caprylic Acid from Maize Silage-Based Fermentation Broth

Maria Braune et al. Front Bioeng Biotechnol. .

Erratum in

Abstract

Production of caproic and caprylic acid through anaerobic fermentation of crops or residual and waste biomass has been regarded as an alternative to the conventional ways, where plant oils and animal fats are mostly used. The downstream processing of the fermentation broth is a particular challenge since the broth has a highly complex composition and low concentrations of the target products. In this study, the proof-of-principle for a separation cascade for caproic (C6) and caprylic acid (C8) produced in a maize silage-based fermentation process was demonstrated. For clarification of the fermentation broth, a filter press and a ceramic ultrafiltration membrane was used to remove coarse solids and to separate suspended particles and macromolecules from the fermentation broth, respectively. With both techniques, the dry matter content was reduced from 6.8 to 2.3% and a particle-free product solution was obtained. Subsequently, the carboxylic acids were extracted with oleyl alcohol by liquid-liquid extraction with an extraction efficiency of 85% for C6 and 97% for C8. Over the whole cascade, 58% of caproic acid and 66% of caprylic acid were recovered from the fermentation broth into the extract. Among all separation steps, solid-liquid separation with the filter press caused the major part of the product loss of 21% of each carboxylic acid. By using separation equipment with a better solid separation efficiency such as decanter centrifuges or belt filter presses this loss could be minimized.

Keywords: anaerobic fermentation; biorefinery; chain elongation; liquid-liquid extraction; medium-chain carboxylates; ultrafiltration.

PubMed Disclaimer

Conflict of interest statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

FIGURE 1
FIGURE 1
Proposed downstream processing cascade for separation of caproic (C6) and caprylic acid (C8) from fermentation broth obtained by anaerobic fermentation of maize silage.
FIGURE 2
FIGURE 2
Schematic diagram of the crossflow filtration system.
FIGURE 3
FIGURE 3
Schematic diagram (A) and photo (B) of the stirred cell extraction column.
FIGURE 4
FIGURE 4
Influence of transmembrane pressure on permeate flux and determination of critical and limiting permeate flux.
FIGURE 5
FIGURE 5
Permeate flux and volume reduction during the concentration of filtrate, dilution due to periodic refilling.
FIGURE 6
FIGURE 6
Extraction efficiency (E) and concentrations of different carboxylic acids in the feed and raffinate stream.
FIGURE 7
FIGURE 7
Overall mass balance of the downstream processing cascade including caproic (C6) and caprylic acid (C8) concentrations (FB: fermentation broth).
See this image and copyright information in PMC

References

    1. Aghapour Aktij S., Zirehpour A., Mollahosseini A., Taherzadeh M. J., Tiraferri A., Rahimpour A. (2020). Feasibility of Membrane Processes for the Recovery and Purification of Bio-Based Volatile Fatty Acids: A Comprehensive Review. J. Ind. Eng. Chem. 81, 24–40. 10.1016/j.jiec.2019.09.009 - DOI
    1. Alkaya E., Kaptan S., Ozkan L., Uludag-Demirer S., Demirer G. N. (2009). Recovery of Acids from Anaerobic Acidification Broth by Liquid-Liquid Extraction. Chemosphere 77, 1137–1142. 10.1016/j.chemosphere.2009.08.027 - DOI - PubMed
    1. Angenent L. T., Richter H., Buckel W., Spirito C. M., Steinbusch K. J. J., Plugge C. M., et al. (2016). Chain Elongation with Reactor Microbiomes: Open-Culture Biotechnology to Produce Biochemicals. Environ. Sci. Technol. 50, 2796–2810. 10.1021/acs.est.5b04847 - DOI - PubMed
    1. Bekatorou A., Dima A., Tsafrakidou P., Boura K., Lappa K., Kandylis P., et al. (2016). Downstream Extraction Process Development for Recovery of Organic Acids from a Fermentation Broth. Bioresour. Technol. 220, 34–37. 10.1016/j.biortech.2016.08.039 - DOI - PubMed
    1. Benítez F. J., Acero J. L., Leal A. I., González M. (2009). The Use of Ultrafiltration and Nanofiltration Membranes for the Purification of Cork Processing Wastewater. J. Hazard. Mater. 162, 1438–1445. 10.1016/j.jhazmat.2008.06.036 - DOI - PubMed

LinkOut - more resources