Controlling accumulation of fermentation inhibitors in biorefinery recycle water using microbial fuel cells

Borole, Mielenz, Vishnivetskaya, Hamilton

Description

Microbial fuel cells (MFC) and microbial electrolysis cells are electrical devices that treat water using microorganisms and convert soluble organic matter into electricity and hydrogen, respectively. Emerging cellulosic biorefineries are expected to use large amounts of water during production of ethanol. Pretreatment of cellulosic biomass results in production of fermentation inhibitors which accumulate in process water and make the water recycle process difficult. Use of MFCs to remove the inhibitory sugar and lignin degradation products from recycle water is investigated in this study. Results Use of an MFC to reduce the levels of furfural, 5-hydroxymethylfurfural, vanillic acid, 4-hydroxybenzaldehyde and 4-hydroxyacetophenone while simultaneously producing electricity is demonstrated here. An integrated MFC design approach was used which resulted in high power densities for the MFC, reaching up to 3700 mW/m 2 (356 W/m 3 net anode volume) and a coulombic efficiency of 69%. The exoelectrogenic microbial consortium enriched in the anode was characterized using a 16S rRNA clone library method. A unique exoelectrogenic microbial consortium dominated by δ-Proteobacteria (50%), along with β-Proteobacteria (28%), α-Proteobacteria (14%), γ-Proteobacteria (6%) and others was identified. The consortium demonstrated broad substrate specificity, ability to handle high inhibitor concentrations (5 to 20 mM) with near complete removal, while maintaining long-term stability with respect to power production. Conclusion Use of MFCs for removing fermentation inhibitors has implications for: 1) enabling higher ethanol yields at high biomass loading in cellulosic ethanol biorefineries, 2) improved water recycle and 3) electricity production up to 25% of total biorefinery power needs.

Informations

• Publié par: biomed
• Publié le: 01 janvier 2009
• Nombre de lectures: 6
• Langue: English
• Poids de l'ouvrage: 1 Mo

Extrait

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Abstract Background: Microbial fuel cells (MFC) an d microbial electrolysis cell s are electrical devices that treat water using microorg anisms and convert soluble organic ma tter into electricity and hydrogen, respectively. Emerging cellulosic biorefineries are expected to us e large amounts of water during production of ethanol. Pretreatment of cellulosic biomass results in production of fermentation inhibitors which accumulate in process water and make the wate r recycle process difficult. Use of MFCs to remove the inhibitory sugar and lignin degradation products from recycle water is investigated in this study. Results: Use of an MFC to reduce the levels of furf ural, 5-hydroxymethylfurfural, vanillic acid, 4- hydroxybenzaldehyde and 4-hydroxyacetophenone while simultaneously producing electricity is demonstrated here. An integrated MFC design ap proach was used which resulted in high power densities for the MFC, reaching up to 3700 mW/m 2 (356 W/m 3 net anode volume) and a coulombic efficiency of 69%. The exoelectr ogenic microbial consortium enriched in the anode was characterized using a 16S rRNA clone librar y method. A unique exoelectrogenic microbial consortium dominated by δ -Proteobacteria (50%), along with β -Proteobacteria (28%), α - Proteobacteria (14%), γ -Proteobacteria (6%) and others was identified. The consortium demonstrated broad substrate specificity, ability to handle high inhibitor concentrations (5 to 20 mM) with near complete removal, while maintaining long-term stability with respect to power production. Conclusion: Use of MFCs for removing fermentation inhi bitors has implications for: 1) enabling higher ethanol yields at high biomass loading in ce llulosic ethanol biorefineries, 2) improved water recycle and 3) electricity production up to 25% of total biorefinery power needs.

Published: 1 April 2009 Received: 23 January 2009 Biotechnology for Biofuels 2009, 2 :7 doi:10.1186/1754-6834-2-7  Accepted: 1 April 2009 This article is available from: http://www. biotechnologyforbiofuels.com/content/2/1/7 © 2009 Borole et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons. org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the orig inal work is properly cited.

Research Open Access Controlling accumulation of fermen tation inhibitors in biorefinery recycle water using microbial fuel cells Abhijeet P Borole* 1 , Jonathan R Mielenz 1 , Tatiana A Vishnivetskaya 1 and Choo Y Hamilton 2

Address: 1 BioSciences Division, Oak Ridg e National Laboratory, Oak Ridge, TN 37831-6226, USA and 2 The University of Tennessee, Knoxville, TN 37996, USA Email: Abhijeet P Borole* - borolea @ornl.gov; Jonathan R Mielenz - Mie [e-mail]; Tatiana A Vishni vetskaya - [e-mail]; Choo Y Hamilton - [e-mail] * Corresponding author

Background microorganisms as catalysts (Figure 1). Conversion of sug- Microbial fuel cells (MFCs) are devices which convert ars, organic acids and other degradable matter to electric- organic matter to energy (electricity or hydrogen) using ity has been demonstrated [1,2]. The use of this

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