Dynamic changes in anaerobic digester metabolic pathways and microbial populations during acclimatisation to increasing ammonium concentrations
Dynamic changes in anaerobic digester metabolic pathways and microbial populations during acclimatisation to increasing ammonium concentrations
Transitions in microbial community structure in response to increasing ammonia concentrations were determined by monitoring mesophilic anaerobic digesters seeded with a predominantly acetoclastic methanogenic community from a sewage sludge digester. Ammonia concentration was raised by switching the feed to source segregated domestic food waste and applying two organic loading rates (OLR) and hydraulic retention times (HRT) in paired digesters. One of each pair was dosed with trace elements (TE) known to be essential to the transition, with the other unsupplemented digester acting as a control. Samples taken during the trial were used to determine the metabolic pathway to methanogenesis using 14C labelled acetate. Partitioning of 14C between the product gases was interpreted via an equation to indicate the proportion produced by acetoclastic and hydrogenotrophic routes. Archaeal and selected bacterial groups were identified by 16S rRNA sequencing, to determine relative abundance and diversity. Acclimatisation for digesters with TE was relatively smooth, but OLR and HRT influenced both metabolic route and community structure. The 14C ratio could be used quantitatively and, when interpreted alongside archaeal community structure, showed that at longer HRT and lower loading Methanobacteriaceae were dominant and hydrogenotrophic activity accounted for 77% of methane production. At the higher OLR and shorter HRT, Methanosarcinaceae were dominant with the 14C ratio indicating simultaneous production of methane by acetoclastic and hydrogenotrophic pathways: the first reported observation of this in digestion under mesophilic conditions. Digesters without TE supplementation showed similar initial changes but, as expected failed to complete the transition to stable operation.
14C labelling, acetoclastic methanogenesis, ammonia, anaerobic digestion, hydrogenotrophic methanogenesis, trace elements
409-419
Zhang, Wei
e896f9bd-f169-4c5a-a465-cadf5d5a96a3
Alessi, Anna M.
b8c92e5e-a720-42cb-8ef8-b978a9f1ee9c
Heaven, Sonia
f25f74b6-97bd-4a18-b33b-a63084718571
Chong, James
4e4ecdde-b11e-4efa-b40b-73f0c6f62160
Banks, Charles
5c6c8c4b-5b25-4e37-9058-50fa8d2e926f
November 2021
Zhang, Wei
e896f9bd-f169-4c5a-a465-cadf5d5a96a3
Alessi, Anna M.
b8c92e5e-a720-42cb-8ef8-b978a9f1ee9c
Heaven, Sonia
f25f74b6-97bd-4a18-b33b-a63084718571
Chong, James
4e4ecdde-b11e-4efa-b40b-73f0c6f62160
Banks, Charles
5c6c8c4b-5b25-4e37-9058-50fa8d2e926f
Zhang, Wei, Alessi, Anna M., Heaven, Sonia, Chong, James and Banks, Charles
(2021)
Dynamic changes in anaerobic digester metabolic pathways and microbial populations during acclimatisation to increasing ammonium concentrations.
Waste Management, 135, .
(doi:10.1016/j.wasman.2021.09.017).
Abstract
Transitions in microbial community structure in response to increasing ammonia concentrations were determined by monitoring mesophilic anaerobic digesters seeded with a predominantly acetoclastic methanogenic community from a sewage sludge digester. Ammonia concentration was raised by switching the feed to source segregated domestic food waste and applying two organic loading rates (OLR) and hydraulic retention times (HRT) in paired digesters. One of each pair was dosed with trace elements (TE) known to be essential to the transition, with the other unsupplemented digester acting as a control. Samples taken during the trial were used to determine the metabolic pathway to methanogenesis using 14C labelled acetate. Partitioning of 14C between the product gases was interpreted via an equation to indicate the proportion produced by acetoclastic and hydrogenotrophic routes. Archaeal and selected bacterial groups were identified by 16S rRNA sequencing, to determine relative abundance and diversity. Acclimatisation for digesters with TE was relatively smooth, but OLR and HRT influenced both metabolic route and community structure. The 14C ratio could be used quantitatively and, when interpreted alongside archaeal community structure, showed that at longer HRT and lower loading Methanobacteriaceae were dominant and hydrogenotrophic activity accounted for 77% of methane production. At the higher OLR and shorter HRT, Methanosarcinaceae were dominant with the 14C ratio indicating simultaneous production of methane by acetoclastic and hydrogenotrophic pathways: the first reported observation of this in digestion under mesophilic conditions. Digesters without TE supplementation showed similar initial changes but, as expected failed to complete the transition to stable operation.
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Accepted/In Press date: 18 September 2021
e-pub ahead of print date: 4 October 2021
Published date: November 2021
Additional Information:
Funding Information:
This work was carried out with funding and support from the Engineering and Physical Sciences Research Council through the IBCat H2AD project (EP/M028208/1). JPJC is a Royal Society Industry Fellow (IF160022)
Funding Information:
This work was carried out with funding and support from the Engineering and Physical Sciences Research Council through the IBCat H2AD project (EP/M028208/1). JPJC is a Royal Society Industry Fellow (IF160022)
Publisher Copyright:
© 2021 Elsevier Ltd
Keywords:
14C labelling, acetoclastic methanogenesis, ammonia, anaerobic digestion, hydrogenotrophic methanogenesis, trace elements
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Local EPrints ID: 451661
URI: http://eprints.soton.ac.uk/id/eprint/451661
ISSN: 0956-053X
PURE UUID: 0d31c3d2-ea64-4d05-b04c-d9d2c405e5c9
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Date deposited: 18 Oct 2021 16:32
Last modified: 17 Mar 2024 06:51
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Author:
Wei Zhang
Author:
Anna M. Alessi
Author:
James Chong
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