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Coupling organic waste oxidation to microbial electrosynthesis for the energy-efficient production of platform chemicals: lessons from the French "BIORARE" project

Authors
  • Bouchez, T.
  • Bernet, N.
  • Bergel, Alain
  • Aissani, Lynda
  • Huyard, A.
Publication Date
Sep 28, 2016
Source
HAL-Descartes
Keywords
Language
English
License
Unknown
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Abstract

The BIORARE project started by the end of year 2011 and has gathered a consortium of 5 partners in the framework of a French "Investissement d'Avenir" program (ANR-10-BTBR-02). The objective is to evaluate how bioelectrochemical systems (BES) could be integrated into existing waste treatment facilities to promote the emergence of environmental biorefineries where oxidation of waste would be coupled to the production of platform chemicals through energy efficient CO2 reduction. This evaluation is based not only on scientific and technological criteria (three workpackages) but also on environmental assessment of selected scenarios and first analysis of associated industrial constraints (two workpackages). The starting working hypothesis is that the BES could be coupled to a two step anaerobic digestion process encompassing hydrolysis and methanogenesis reactors (Figure 1). The procedures for drawing electrons out of various residual organic feedstock (sludges, biowaste) at high current densities ranging from 7 to 30 A/m2 were established. At the cathode, the possibility of microbial electrosynthesis of multicarbon platform chemicals through CO2 reduction by a mixed culture consortia was confirmed. Various procedures allowing the operation of BES comprising a bioanode oxidizing waste materials coupled to a cathode synthesizing platform organics were defined and patented. Stable operation of labscale BIORARE reactors were obtained during several months constituting first proofs of technological concept (TRL3). The comparison with BESs equipped with an abiotic anode, which achieved water oxidation, showed that the bioanode reduced the electric power consumption of a factor two to three. Performances of larger optimized reactors are currently being studied. Conclusions drawn from first Life Cycle Assessment performed on selected BES implementation schemes and associated industrial constraints will be discussed. Even if numerous technological, environmental and socio economical hurdles still need to be overcome, the results of the BIORARE project also highlight the great potential of BES to become a technological cornerstone of future environmental biorefineries.

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