title: Quantifying the percentage of methane formation via acetoclastic and syntrophic acetate oxidation pathways in anaerobic digesters.
abstract: Ammonia concentration is one of the key factors influencing the methanogenic community composition and dominant methanogenic pathway in anaerobic digesters. This study adopted a radiolabelling technique using [2-14C] acetate to investigate the relationship between total ammonia nitrogen (TAN) and the methanogenic pathway. The radiolabelling experiments determined the ratio of14CO2and14CH4in the biogas which was used to quantitatively determine the percentage of CH4derived from acetoclastic and syntrophic acetate oxidation routes, respectively. This technique was performed on a selection of mesophilic digesters representing samples of low to high TAN concentrations (0.2-11.1gkg-1wet weight). In high TAN digesters, the ratio between14CO2and14CH4was in the range 2.1-3.0; indicating 68-75% of methane was produced via the hydrogenotrophic route; whereas in low ammonia samples the ratio was 0.1-0.3, indicating 9-23% of methane was produced by the hydrogenotrophic route. These findings have been confirmed further by phylogenetic studies.
authors.affiliation: Centre for Bioenergy & Resource Management, School of Water, Energy and Environment, Cranfield University, Cranfield MK43 0AL, UK. Electronic address: Y.Jiang@cranfield.ac.uk.
authors.forename: Ying
authors.initials: Y
authors.lastname: Jiang
authors.affiliation: Faculty of Engineering and the Environment, University of Southampton, Southampton SO17 1BJ, UK.
authors.forename: Charles
authors.initials: C
authors.lastname: Banks
authors.affiliation: Faculty of Engineering and the Environment, University of Southampton, Southampton SO17 1BJ, UK.
authors.forename: Yue
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Faculty of Engineering and the Environment, University of Southampton, Southampton SO17 1BJ, UK.
authors.forename: Sonia
authors.initials: S
authors.lastname: Heaven
authors.affiliation: Centre for Bioenergy & Resource Management, School of Water, Energy and Environment, Cranfield University, Cranfield MK43 0AL, UK.
authors.forename: Philip
authors.initials: P
authors.lastname: Longhurst
mesh_terms: D019342:Acetic Acid; D000641:Ammonia; D000693:Anaerobiosis; D019149:Bioreactors; D008697:Methane / Q000032:analysis*; D010084:Oxidation-Reduction
chemical_list: D000641:Ammonia; D008697:Methane; D019342:Acetic Acid
keywords: Ammonia inhibition; Anaerobic digestion; Food waste; Methanogenic pathway; Radioactive isotope labelling