Assessment of micro-scale anaerobic digestion for management of urban organic waste: A case study in London, UK
Assessment of micro-scale anaerobic digestion for management of urban organic waste: A case study in London, UK
This paper describes the analysis of an AD plant that is novel in that it is located in an urban environment, built on a micro-scale, fed on food and catering waste, and operates as a purposeful system. The plant was built in 2013 and continues to operate to date, processing urban food waste and generating biogas for use in a community café. The plant was monitored for a period of 319 days during 2014, during which the operational parameters, biological stability and energy requirements of the plant were assessed. The plant processed 4574 kg of food waste during this time, producing 1008 m3 of biogas at average 60.6 % methane. The results showed that the plant was capable of stable operation despite large fluctuations in the rate and type of feed. Another innovative aspect of the plant was that it was equipped with a pre-digester tank and automated feeding, which reduced the effect offeedstock variations on the digestion process. Towards the end of the testing period, a rise in the concentration of volatile fatty acids and ammonia was detected in the digestate, indicating biological instability, and this was successfully remedied by adding trace elements. The energy balance and coefficient of performance (COP) of the system were calculated, which concluded that the system used 49% less heat energy by being housed in a greenhouse, achieved a net positive energy balance and potential COP of 3.16 and 5.55 based on electrical and heat energy, respectively. Greenhouse gas emissions analysis concluded that the most important contribution of the plant to the mitigation of greenhouse gases was the avoidance of on-site fossil fuel use, followed by the diversion of food waste from landfill and that the plant could result in carbon reduction of 2.95 kg CO2eq kWh-1 electricity production or 0.741 kg CO2eq kg-1 waste treated.
anaerobic digestion, biogas, Food waste, Urban organic waste, Ammonia inhibition, micro-scale
258-268
Walker, Mark
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Theaker, Helen
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Yaman, Rokiah
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Poggio, Davide
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Nimmo, William
e427791e-8d60-453b-ba44-7257c44325c4
Bywater, Angela
293fa6f5-71eb-4b69-a24c-58753b58ed4c
Pourkashanian, Mohamed
eb3be025-19c9-4449-be09-02c644f5c948
March 2017
Walker, Mark
440e66f0-fce4-45cf-a73d-3716f254d87f
Theaker, Helen
db0e6128-f64e-4c0f-809b-4f8e9b1f5790
Yaman, Rokiah
64a4ed05-b88a-4526-86d2-351495acd751
Poggio, Davide
d08adbdf-66ed-44ba-8d4f-13f295dd8ac2
Nimmo, William
e427791e-8d60-453b-ba44-7257c44325c4
Bywater, Angela
293fa6f5-71eb-4b69-a24c-58753b58ed4c
Pourkashanian, Mohamed
eb3be025-19c9-4449-be09-02c644f5c948
Walker, Mark, Theaker, Helen, Yaman, Rokiah, Poggio, Davide, Nimmo, William, Bywater, Angela and Pourkashanian, Mohamed
(2017)
Assessment of micro-scale anaerobic digestion for management of urban organic waste: A case study in London, UK.
Waste Management, 61, .
(doi:10.1016/j.wasman.2017.01.036).
Abstract
This paper describes the analysis of an AD plant that is novel in that it is located in an urban environment, built on a micro-scale, fed on food and catering waste, and operates as a purposeful system. The plant was built in 2013 and continues to operate to date, processing urban food waste and generating biogas for use in a community café. The plant was monitored for a period of 319 days during 2014, during which the operational parameters, biological stability and energy requirements of the plant were assessed. The plant processed 4574 kg of food waste during this time, producing 1008 m3 of biogas at average 60.6 % methane. The results showed that the plant was capable of stable operation despite large fluctuations in the rate and type of feed. Another innovative aspect of the plant was that it was equipped with a pre-digester tank and automated feeding, which reduced the effect offeedstock variations on the digestion process. Towards the end of the testing period, a rise in the concentration of volatile fatty acids and ammonia was detected in the digestate, indicating biological instability, and this was successfully remedied by adding trace elements. The energy balance and coefficient of performance (COP) of the system were calculated, which concluded that the system used 49% less heat energy by being housed in a greenhouse, achieved a net positive energy balance and potential COP of 3.16 and 5.55 based on electrical and heat energy, respectively. Greenhouse gas emissions analysis concluded that the most important contribution of the plant to the mitigation of greenhouse gases was the avoidance of on-site fossil fuel use, followed by the diversion of food waste from landfill and that the plant could result in carbon reduction of 2.95 kg CO2eq kWh-1 electricity production or 0.741 kg CO2eq kg-1 waste treated.
Text
Walker et al_2017_WM_Author copy
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More information
In preparation date: 19 January 2017
Accepted/In Press date: 24 January 2017
e-pub ahead of print date: 6 February 2017
Published date: March 2017
Additional Information:
Acknowledgments
The authors would like to acknowledge WRAP DIAD II for funding the construction and operation of the AD plant (full copy of the project report available from www.wrap.org.uk) and the School of Process Engineering at the University of Leeds for access to their laboratories and analytical equipment. Thanks go to the LEAP consortium, which included Community by Design, James Murcott and Angela Bywater at Methanogen UK Ltd, Guy Blanch Bio Development, Dr David Neylan, Clive Andrews at Aleka Designs and Cath Kibbler at the Community Composting Network. The generous contributions of the voluntary Community by Design site staff; Marco Fanasca, Panteha Ahmadi and Tasos Torounidis, are also acknowledged.
Keywords:
anaerobic digestion, biogas, Food waste, Urban organic waste, Ammonia inhibition, micro-scale
Organisations:
Water & Environmental Engineering Group
Identifiers
Local EPrints ID: 408472
URI: http://eprints.soton.ac.uk/id/eprint/408472
ISSN: 0956-053X
PURE UUID: 935c3b62-5e69-4125-be80-bac58c964687
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Date deposited: 20 May 2017 04:05
Last modified: 16 Mar 2024 05:15
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Contributors
Author:
Mark Walker
Author:
Helen Theaker
Author:
Rokiah Yaman
Author:
Davide Poggio
Author:
William Nimmo
Author:
Mohamed Pourkashanian
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