title: Biological carbon dioxide utilisation in food waste anaerobic digesters.
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.
authors.affiliation: Cranfield University, Cranfield, Bedfordshire, MK43 0AL, UK.
authors.forename: Y Bajón
authors.initials: YB
authors.lastname: Fernández
authors.affiliation: Cranfield University, Cranfield, Bedfordshire, MK43 0AL, UK.
authors.forename: K
authors.initials: K
authors.lastname: Green
authors.affiliation: Ecole Nationale Supérieure de Chimie de Rennes, 11 Allée de Beaulieu, 35708 Rennes Cedex 7, France.
authors.forename: K
authors.initials: K
authors.lastname: Schuler
authors.affiliation: Cranfield University, Cranfield, Bedfordshire, MK43 0AL, UK.
authors.forename: A
authors.initials: A
authors.lastname: Soares
authors.affiliation: Severn Trent Water, 2 St John's Street, Coventry, CV1 2LZ, UK.
authors.forename: P
authors.initials: P
authors.lastname: Vale
authors.affiliation: Department of Industrial Engineering, University of Padova, Via Marzolo 9, 35131 Padova, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Alibardi
authors.affiliation: Cranfield University, Cranfield, Bedfordshire, MK43 0AL, UK. Electronic address: E.Cartmell@cranfield.ac.uk.
authors.forename: E
authors.initials: E
authors.lastname: Cartmell
mesh_terms: D000693:Anaerobiosis; D056804:Biofuels / Q000032:analysis*; D019149:Bioreactors; D002245:Carbon Dioxide / Q000032:analysis / Q000378:metabolism*; D005232:Fatty Acids, Volatile / Q000032:analysis; D005735:Garbage; D006859:Hydrogen / Q000032:analysis; D012037:Refuse Disposal / Q000379:methods*
chemical_list: D056804:Biofuels; D005232:Fatty Acids, Volatile; D002245:Carbon Dioxide; D006859:Hydrogen
keywords: Anaerobic digestion; Bubble column; Carbon dioxide utilisation; Food waste; Hydrogen