Okoro-Shekwaga, CK, Ross, AB and Camargo-Valero, MA orcid.org/0000-0003-2962-1698 (2021) Enhanced in-situ biomethanation of food waste by sequential inoculum acclimation: Energy efficiency and carbon savings analysis. Waste Management, 130. pp. 12-22. ISSN 0956-053X
Abstract
The increasing rate of food waste (FW) generation globally, makes it an attractive resource for renewable energy through anaerobic digestion (AD). The biogas recovered from AD can be upgraded by the methanation of internally produced carbon dioxide, CO2 with externally sourced hydrogen gas, H2 (biomethanation). In this work, H2 was added to AD reactors processing FW in three successive phases, with digestate from preceding phases recycled in succession with the addition of fresh inoculum to enhance acclimation. The concentration of H2 was increased for succeeding phases: 5%, 10% and 15% of the reactor headspace in Phase 1 (EH1), Phase 2 (EH2) and Phase 3 (EH3), respectively. The H2 utilisation rate and biomethane yields increased as acclimation progressed from EH1 through EH3. Biomethane yield from the controls: EH1_Control, EH2_Control and EH3_Control were 417.6, 435.4 and 453.3 NmL-CH4/gVSadded accounting for 64.8, 73.9 and 77.8% of the biogas respectively. And the biomethane yield from the test reactors EH1_Test, EH2_Test and EH3_Test were 468.3, 483.6, and 499.0 NmL-CH4/gVSadded, accounting for 77.2, 78.1 and 81.0% of the biogas respectively. A progressive in-situ biomethanation could lead to biomethane production that meets higher fuel standards for gas-to-grid (GtG) injections and vehicle fuel – i.e. >95% CH4. This would increase the energy yield and carbon savings compared to conventional biogas upgrade methods. For example, biogas upgrade for GtG by in-situ biomethanation could yield 7.3 MWh/tFW energy and 1343 kg-CO2e carbon savings, which is better than physicochemical upgrade options (i.e., 4.6–4.8 MWh/tFW energy yield and 846–883 kg-CO2e carbon savings).
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2021 Elsevier Ltd. All rights reserved. This is an author produced version of an article published in Waste Management. Uploaded in accordance with the publisher's self-archiving policy. |
Keywords: | Biomethanation; Hydrogen; Food waste; Biomethane; Energy balance; Carbon saving |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Civil Engineering (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 10 Jun 2021 14:33 |
Last Modified: | 24 May 2022 00:38 |
Status: | Published |
Publisher: | Elsevier |
Identification Number: | 10.1016/j.wasman.2021.04.053 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:175003 |
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