{"id":{"repo_id":"cambridge","oai_identifier":"oai:www.repository.cam.ac.uk:1810/368530"},"canonical_url":"https://search.dev.ndltd.org/etd/cambridge/oai:www.repository.cam.ac.uk:1810/368530","repository":{"repo_id":"cambridge","name":"Cambridge University","base_url":"https://api.repository.cam.ac.uk/server/oai/request"},"display":{"title":"Energy recovery from urine","abstract":"Removal of nitrogen compounds in wastewater represents more than 10% of the total electrical demand of the integral water cycle. However, more than 80% of the nitrogen in wastewater comes from urine, where it is highly concentrated in the form of urea (20000 mg L-1). Urea contains a significant amount of hydrogen in its structure which, if recovered, makes urea a potential source of green energy. This thesis demonstrates a novel approach for the energy recovery from urea present in urine at the production source, using decentralised wastewater treatment systems. A new process has been developed in this thesis based on the integration of three steps. In the first step, adsorption is used to recover urea from urea, overcoming the energy limitations of thermal treatments applied to big water volumes. In the second step, thermal treatment is used to desorb the urea, achieving the regeneration of the adsorbent and the production of ammonia. Finally, in the third step, ammonia is used as hydrogen storage molecule to catalytically produce hydrogen on demand. The adsorption of urea is evaluated using activated carbon, determining that urea adsorbs due to physical interactions with i) delocalised π electrons of the pristine surface of the carbon and ii) carboxyl functional groups. The adsorption of urea is reduced when working with real urine due to the presence of organic compounds with affinity for activated carbon that interferes with the adsorption of urea. Thermal treatment of adsorbed urea leads to desorption of urea and regeneration of activated carbon showing a stable urea adsorption capacity during 4 consecutive adsorption/desorption cycles. Simultaneously, ammonia is produced with a 50 – 60 % yield, which is coupled with an ammonia decomposition catalyst to obtain hydrogen. Pilot trials are developed and installed in relevant environments as conventional and waterless urinals, where a social analysis shows a good acceptance towards the solution and pointed some aspects for improving. Energy analysis shows a positive balance due to the combination of the hydrogen produced and the savings in the traditional nitrogen removal. Furthermore, economic analysis indicates that the direct use of ammonia to produce electricity or fertilisers can be a competitive alternative to the obtention of hydrogen.","abstract_html":"Removal of nitrogen compounds in wastewater represents more than 10% of the total electrical demand of the integral water cycle. However, more than 80% of the nitrogen in wastewater comes from urine, where it is highly concentrated in the form of urea (20000 mg L-1). Urea contains a significant amount of hydrogen in its structure which, if recovered, makes urea a potential source of green energy. This thesis demonstrates a novel approach for the energy recovery from urea present in urine at the production source, using decentralised wastewater treatment systems. A new process has been developed in this thesis based on the integration of three steps. In the first step, adsorption is used to recover urea from urea, overcoming the energy limitations of thermal treatments applied to big water volumes. In the second step, thermal treatment is used to desorb the urea, achieving the regeneration of the adsorbent and the production of ammonia. Finally, in the third step, ammonia is used as hydrogen storage molecule to catalytically produce hydrogen on demand. The adsorption of urea is evaluated using activated carbon, determining that urea adsorbs due to physical interactions with i) delocalised π electrons of the pristine surface of the carbon and ii) carboxyl functional groups. The adsorption of urea is reduced when working with real urine due to the presence of organic compounds with affinity for activated carbon that interferes with the adsorption of urea. Thermal treatment of adsorbed urea leads to desorption of urea and regeneration of activated carbon showing a stable urea adsorption capacity during 4 consecutive adsorption/desorption cycles. Simultaneously, ammonia is produced with a 50 – 60 % yield, which is coupled with an ammonia decomposition catalyst to obtain hydrogen. Pilot trials are developed and installed in relevant environments as conventional and waterless urinals, where a social analysis shows a good acceptance towards the solution and pointed some aspects for improving. Energy analysis shows a positive balance due to the combination of the hydrogen produced and the savings in the traditional nitrogen removal. Furthermore, economic analysis indicates that the direct use of ammonia to produce electricity or fertilisers can be a competitive alternative to the obtention of hydrogen.","abstract_has_math":false,"creators":["Asiain Mira, Ruben"],"institution":"University of Cambridge","degree_name":"Doctor of Philosophy (PhD)","degree_level":"Doctoral","degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":["Torrente Murciano, Laura"],"committee_chairs":[],"committee_members":[],"year":2023,"date_issued":"2023-10-01","date_published":"2023-10-01","updated_at":"2026-07-22T22:24:21Z","subjects":["Activated carbon","Adsorption","Urea","Urine","Water-energy nexus"],"languages":["eng"],"rights":[],"rights_urls":["https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/294708e6-8c7e-450e-a434-2afcb53108de/download","https://www.rioxx.net/licenses/all-rights-reserved/"],"identifier_entries":[]},"links":{"outbound_url":"https://doi.org/10.17863/CAM.108698","outbound_label":"DOI","outbound_source":"dc:identifier.doi"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Torrente Murciano, Laura"]},{"key":"dc:contributor.sponsor","label":"Sponsor","values":["European Union’s Horizon 2020 research and innovation programme in the frame of REWATERGY, Sustainable Reactor Engineering for Applications on the Water-Energy Nexus, MSCA-ITN-EID Project N. 812574"]},{"key":"dc:creator","label":"Author","values":["Asiain Mira, Ruben"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.issued","label":"Date","values":["2023-10-01"]},{"key":"dc:publisher.institution","label":"Dc Publisher Institution","values":["University of Cambridge"]},{"key":"dc:relation.isreferencedby.uri","label":"Dc Relation Isreferencedby URI","values":["https://www.repository.cam.ac.uk/handle/1810/368530"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"dc:type.qualificationlevel","label":"Dc Type Qualificationlevel","values":["Doctoral"]},{"key":"dc:type.qualificationname","label":"Dc Type Qualificationname","values":["Doctor of Philosophy (PhD)"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Activated carbon","Adsorption","Urea","Urine","Water-energy nexus"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["eng"]},{"key":"dc:rights","label":"Dc Rights","values":["https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/294708e6-8c7e-450e-a434-2afcb53108de/download","https://www.rioxx.net/licenses/all-rights-reserved/"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.doi","label":"DOI","values":["https://doi.org/10.17863/CAM.108698"]},{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/116a5225-5f31-46fa-9d71-bb86d58107ea/download"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Removal of nitrogen compounds in wastewater represents more than 10% of the total electrical demand of the integral water cycle. However, more than 80% of the nitrogen in wastewater comes from urine, where it is highly concentrated in the form of urea (20000 mg L-1). Urea contains a significant amount of hydrogen in its structure which, if recovered, makes urea a potential source of green energy. This thesis demonstrates a novel approach for the energy recovery from urea present in urine at the production source, using decentralised wastewater treatment systems. A new process has been developed in this thesis based on the integration of three steps. In the first step, adsorption is used to recover urea from urea, overcoming the energy limitations of thermal treatments applied to big water volumes. In the second step, thermal treatment is used to desorb the urea, achieving the regeneration of the adsorbent and the production of ammonia. Finally, in the third step, ammonia is used as hydrogen storage molecule to catalytically produce hydrogen on demand. The adsorption of urea is evaluated using activated carbon, determining that urea adsorbs due to physical interactions with i) delocalised π electrons of the pristine surface of the carbon and ii) carboxyl functional groups. The adsorption of urea is reduced when working with real urine due to the presence of organic compounds with affinity for activated carbon that interferes with the adsorption of urea. Thermal treatment of adsorbed urea leads to desorption of urea and regeneration of activated carbon showing a stable urea adsorption capacity during 4 consecutive adsorption/desorption cycles. Simultaneously, ammonia is produced with a 50 – 60 % yield, which is coupled with an ammonia decomposition catalyst to obtain hydrogen. Pilot trials are developed and installed in relevant environments as conventional and waterless urinals, where a social analysis shows a good acceptance towards the solution and pointed some aspects for improving. Energy analysis shows a positive balance due to the combination of the hydrogen produced and the savings in the traditional nitrogen removal. Furthermore, economic analysis indicates that the direct use of ammonia to produce electricity or fertilisers can be a competitive alternative to the obtention of hydrogen."]},{"key":"dc:format.checksum.md5","label":"Dc Format Checksum Md5","values":["795bb0f9e2b5a55aca0b6f610629244d","87eda9de84448d1f82354d60eee3eb5f"]},{"key":"dc:title","label":"Title","values":["Energy recovery from urine"]}]}],"canonical_facts":{"dc:contributor.advisor":["Torrente Murciano, Laura"],"dc:contributor.sponsor":["European Union’s Horizon 2020 research and innovation programme in the frame of REWATERGY, Sustainable Reactor Engineering for Applications on the Water-Energy Nexus, MSCA-ITN-EID Project N. 812574"],"dc:creator":["Asiain Mira, Ruben"],"dc:date.issued":["2023-10-01"],"dc:description.abstract":["Removal of nitrogen compounds in wastewater represents more than 10% of the total electrical demand of the integral water cycle. However, more than 80% of the nitrogen in wastewater comes from urine, where it is highly concentrated in the form of urea (20000 mg L-1). Urea contains a significant amount of hydrogen in its structure which, if recovered, makes urea a potential source of green energy. This thesis demonstrates a novel approach for the energy recovery from urea present in urine at the production source, using decentralised wastewater treatment systems. A new process has been developed in this thesis based on the integration of three steps. In the first step, adsorption is used to recover urea from urea, overcoming the energy limitations of thermal treatments applied to big water volumes. In the second step, thermal treatment is used to desorb the urea, achieving the regeneration of the adsorbent and the production of ammonia. Finally, in the third step, ammonia is used as hydrogen storage molecule to catalytically produce hydrogen on demand. The adsorption of urea is evaluated using activated carbon, determining that urea adsorbs due to physical interactions with i) delocalised π electrons of the pristine surface of the carbon and ii) carboxyl functional groups. The adsorption of urea is reduced when working with real urine due to the presence of organic compounds with affinity for activated carbon that interferes with the adsorption of urea. Thermal treatment of adsorbed urea leads to desorption of urea and regeneration of activated carbon showing a stable urea adsorption capacity during 4 consecutive adsorption/desorption cycles. Simultaneously, ammonia is produced with a 50 – 60 % yield, which is coupled with an ammonia decomposition catalyst to obtain hydrogen. Pilot trials are developed and installed in relevant environments as conventional and waterless urinals, where a social analysis shows a good acceptance towards the solution and pointed some aspects for improving. Energy analysis shows a positive balance due to the combination of the hydrogen produced and the savings in the traditional nitrogen removal. Furthermore, economic analysis indicates that the direct use of ammonia to produce electricity or fertilisers can be a competitive alternative to the obtention of hydrogen."],"dc:format.checksum.md5":["795bb0f9e2b5a55aca0b6f610629244d","87eda9de84448d1f82354d60eee3eb5f"],"dc:identifier.doi":["https://doi.org/10.17863/CAM.108698"],"dc:identifier.uri":["https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/116a5225-5f31-46fa-9d71-bb86d58107ea/download"],"dc:language":["eng"],"dc:publisher.institution":["University of Cambridge"],"dc:relation.isreferencedby.uri":["https://www.repository.cam.ac.uk/handle/1810/368530"],"dc:rights":["https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/294708e6-8c7e-450e-a434-2afcb53108de/download","https://www.rioxx.net/licenses/all-rights-reserved/"],"dc:subject":["Activated carbon","Adsorption","Urea","Urine","Water-energy nexus"],"dc:title":["Energy recovery from urine"],"dc:type":["Thesis"],"dc:type.qualificationlevel":["Doctoral"],"dc:type.qualificationname":["Doctor of Philosophy (PhD)"]},"updated_at":"2026-07-22T22:24:21Z"}