Biological carbon dioxide utilisation in food waste anaerobic digesters

Y. Bajón Fernández (1) , K. Green (1) , K. Schuler (2) , A. Soares (3, 1) , P. Vale (4) , L. Alibardi (5) , E Cartmell (1)

1 Cranfield University
2 ISCR - Institut des Sciences Chimiques de Rennes
3 ICGM - Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier
4 Severn Trent Water
5 Department of Industrial Engineering [Padova]

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 m3 CH4·(kg VSfed·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

Domains: Chemical Sciences

Y. Bajón Fernández, K. Green, K. Schuler, A. Soares, P. Vale, et al.. Biological carbon dioxide utilisation in food waste anaerobic digesters. Water Research, 2015, In press. ⟨10.1016/j.watres.2015.06.011⟩. ⟨hal-01162341v1⟩