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Front. Energy Res. | doi: 10.3389/fenrg.2018.00007

Critical biofilm growth throughout unmodified carbon felts allows continuous bioelectrochemical chain elongation from CO2 up to caproate at high current density

 Ludovic Jourdin1, 2*, Sanne Raes1, Cees Buisman1 and  David Strik1
  • 1Sub-department of Environmental Technology, Wageningen University & Research, Netherlands
  • 2Advanced Water Management Centre, The University of Queensland, Australia

Current challenges for microbial electrosynthesis include the production of higher value chemicals than acetate, at high rates, using cheap electrode materials. We demonstrate here the continuous, biofilm-driven production of acetate (C2), n butyrate (nC4), and n-caproate (nC6) from sole CO2 on unmodified carbon felt electrodes. No other organics were detected. This is the first quantified continuous demonstration of n-caproate production from CO2 using an electrode as sole electron donor. During continuous nutrients supply mode a thick biofilm was developed covering the whole thickness of the felt (1.2 cm deep), which coincided with high current densities and organics production rates. Current density reached up to -14 kA m-3electrode (-175 A m-2). Maximum sustained production rates of 9.8 ± 0.65 g L-1 day-1 C2, 3.2 ± 0.1 g L-1 day-1 nC4, and 0.95 ± 0.05 g L-1 day-1 nC6 were achieved (averaged between duplicates), at electron recoveries of 60-100%. Scanning electron micrographs revealed a morphologically highly diverse biofilm with long filamentous microorganism assemblies (~400 µm). n-Caproate is a valuable chemical for various industrial application, e.g. it can be used as feed additives or serve as precursor for liquid biofuels production.

Keywords: bioelectrochemical chain elongation, Microbial Electrosynthesis, Carbon Dioxide Utilization, Biofilm, Caproate, Biocatalysis

Received: 15 Dec 2017; Accepted: 14 Feb 2018.

Edited by:

Sebastià Puig, University of Girona, Spain

Reviewed by:

Pascal E. Saikaly, King Abdullah University of Science and Technology, Saudi Arabia
Mohanakrishna Gunda, Flemish Institute for Technological Research, VITO, Belgium  

Copyright: © 2018 Jourdin, Raes, Buisman and Strik. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Dr. Ludovic Jourdin, Wageningen University & Research, Sub-department of Environmental Technology, Wageningen, Netherlands, ludovic.jourdin@wur.nl