Biological carbon dioxide utilisation in food waste anaerobic digesters. (15th December 2015)

• Record Type: Journal Article
• Authors: Bajón Fernández, Y.; Green, K.; Schuler, K.; Soares, A.; Vale, P.; Alibardi, L.; Cartmell, E.
• Is Part Of: Water research. Volume 87(2015)
• Page Start: 467
• Page End: 475
• Publication Date: 2015-12-15
• Subjects: Carbon dioxide utilisation -- Anaerobic digestion -- Food waste -- Hydrogen -- Bubble column; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2015.06.011
• Languages: English
• ISSNs: 0043-1354

Abstract

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 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. Graphical abstract: Highlights: Utilisation of exogenous CO2 in ADs was investigated. A pilot-scale AD with CO2 injection treating food waste operated for the first time. Injection of CO2 with a bubble column achieved without diluting the AD's headspace. Concentration of H2 increased by 2.5 fold after four CO2 injections. A mechanism of CO2 utilisation has been proposed.