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±0.13m3 CH4·(kgVSfedd)−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 0.55kg 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.
a Cranfield University, Cranfield, Bedfordshire, MK43 0AL, UKidb Ecole Nationale Supérieure de Chimie de Rennes, 11 Allée de Beaulieu, 35708 Rennes Cedex 7, Franceid="aff3">c Severn Trent Water, 2 St John's Street, Coventry, CV1 2LZ, UKid="aff4">d Department of Industrial Engineering, University of Padova, Via Marzolo 9, 35131 Padova, Italy
Recommended Citation:
Y. Bajó,n Ferná,ndeza,et al. Biological carbon dioxide utilisation in food waste anaerobic digesters[J]. water Research,2015-01-01,Volume 87