Transforming wastewater ammonia to carbon free energy: Integrating fuel cell technology with ammonia stripping for direct power production

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dc.contributor.authorDavey, C. J.
dc.contributor.authorLuqmani, Ben
dc.contributor.authorThomas, Navya
dc.contributor.authorMcAdam, Ewan J.
dc.date.accessioned2022-03-29T12:53:48Z
dc.date.available2022-03-29T12:53:48Z
dc.date.issued2022-03-07
dc.description.abstractThe transformation of ammonia from pollutant to energy rich carbon free fuel presents an opportunity for the transition of wastewater services to net zero. However, there is only limited knowledge of how the product quality of ammonia recovered from real wastewater might impact on its downstream exploitation in fuel cells. This study therefore exploited vacuum stripping to produce an aqueous ammonia concentrate from real wastewater that was then evaluated within a direct ammonia fuel cell, as a reference technology for energy generation. A 17 g L−1 aqueous ammonia product was created by vacuum stripping centrate from a full-scale anaerobic digester (2 gN L−1). The pH of the product was lower than expected due to the mild-acidification of solution by the co-transport of low MW volatile organic compounds. This reduced power density in the fuel cell, due to the incomplete deprotonation of ammonia (lowering oxidation potential at the fuel cell anode) and a decrease in [OH–] which is required for complete electrochemical conversion. We propose that improved vacuum stripping design can increase the distillate ammonia concentration and produce a more alkaline product, yielding markedly higher fuel cell power density by enhancing ammonia oxidation at the anode (through concentration and deprotonation) and reducing [OH–] mass transfer limitations. As the separation energy for ammonia is dominated by the latent heat demand of water vapour, a synergy exists between creation of a concentrated ammonia product (that improves power density) and reducing the energy demand for separation. The energy balance from this research evidences that despite the high latent heat demand for separation, the low cost of heat coupled with the power produced from ammonia yield a favourable economic return when compared to conventional biological treatment. This study also identifies that revaluing ammonia as a carbon free fuel can help reposition wastewater treatment for a zero-carbon future.en_UK
dc.description.sponsorshipEngineering and Physical Sciences Research Council (EPSRC): EP/S036237/1en_UK
dc.identifier.citationDavey CJ, Luqmani B, Thomas N, McAdam EJ. (2022) Transforming wastewater ammonia to carbon free energy: Integrating fuel cell technology with ammonia stripping for direct power production, Separation and Purification Technology, Volume 289, May 2022, Article number 120755en_UK
dc.identifier.issn1383-5866
dc.identifier.urihttps://doi.org/10.1016/j.seppur.2022.120755
dc.identifier.urihttp://dspace.lib.cranfield.ac.uk/handle/1826/17704
dc.language.isoenen_UK
dc.publisherElsevieren_UK
dc.rightsAttribution 4.0 International*
dc.rights.urihttp://creativecommons.org/licenses/by/4.0/*
dc.subjectAmmonia fuel cellen_UK
dc.subjectWastewateren_UK
dc.subjectNet zeroen_UK
dc.subjectEnergy neutralityen_UK
dc.subjectVacuum strippingen_UK
dc.subjectWaste heaten_UK
dc.titleTransforming wastewater ammonia to carbon free energy: Integrating fuel cell technology with ammonia stripping for direct power productionen_UK
dc.typeArticleen_UK

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