Long-term operation of microbial electrosynthesis cell reducing CO2 to multi-carbon chemicals with a mixed culture avoiding methanogenesis
  • Author:
    Suman Bajracharya, Rustiana Yuliasni, Karolien Vanbroekhoven, Cees Buisman, David P B T B Strik, Deepak Pant
  • Abstract:

    In microbial electrosynthesis (MES), CO2 can be reduced preferably to multi-carbon chemicals by a biocathode-based process which uses electrochemically active bacteria as catalysts. A mixed anaerobic consortium from biological origin typically produces methane from CO2 reduction which circumvents production of multi-carbon compounds. 

    This study aimed to develop a stable and robust CO2 reducing biocathode from a mixed culture inoculum avoiding the methane generation. An effective approach was demonstrated based on (i) an enrichment procedure involving inoculum pre-treatment and several culture transfers in H2:CO2 media, (ii) a transfer from heterotrophic to autotrophic growth and (iii) a sequential batch operation. Biomass growth and gradual acclimation to CO2 electro-reduction accomplished a maximum acetate production rate of 400 mg Lcatholyte− 1 d− 1 at − 1 V (vs. Ag/AgCl). Methane was never detected in more than 300 days of operation. Accumulation of acetate up to 7–10 g L− 1 was repeatedly attained by supplying (80:20) CO2:N2 mixture at − 0.9 to − 1 V (vs. Ag/AgCl). In addition, ethanol and butyrate were also produced from CO2 reduction. 

    Thus, a robust CO2 reducing biocathode can be developed from a mixed culture avoiding methane generation by adopting the specific culture enrichment and operation procedures without the direct addition of chemical inhibitor.

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  • Sector:
    Sustainability    Biorefinery   
  • Publication Type:
    Research Article
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