Biological carbon dioxide utilisation in food waste anaerobic digesters

Water Res. 2015 Dec 15:87:467-75. doi: 10.1016/j.watres.2015.06.011. Epub 2015 Jun 9.

Abstract

Carbon dioxide (CO2) enrichment of anaerobic digesters (AD) was previously identified as a potential on-site carbon revalorisation strategy. This study addresses the lack of studies investigating this concept in up-scaled units and the need to understand the mechanisms of exogenous CO2 utilisation. Two pilot-scale ADs treating food waste were monitored for 225 days, with the test unit being periodically injected with CO2 using a bubble column. The test AD maintained a CH4 production rate of 0.56 ± 0.13 m(3) CH4·(kg VS(fed) d)(-1) and a CH4 concentration in biogas of 68% even when dissolved CO2 levels were increased by a 3 fold over the control unit. An additional uptake of 0.55 kg of exogenous CO2 was achieved in the test AD during the trial period. A 2.5 fold increase in hydrogen (H2) concentration was observed and attributed to CO2 dissolution and to an alteration of the acidogenesis and acetogenesis pathways. A hypothesis for conversion of exogenous CO2 has been proposed, which requires validation by microbial community analysis.

Keywords: Anaerobic digestion; Bubble column; Carbon dioxide utilisation; Food waste; Hydrogen.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anaerobiosis
  • Biofuels / analysis*
  • Bioreactors*
  • Carbon Dioxide / analysis
  • Carbon Dioxide / metabolism*
  • Fatty Acids, Volatile / analysis
  • Garbage
  • Hydrogen / analysis
  • Refuse Disposal / methods*

Substances

  • Biofuels
  • Fatty Acids, Volatile
  • Carbon Dioxide
  • Hydrogen