Pilot-scale membrane bioreactor for source-separated urine: Impact of hydraulic retention time on fertiliser production

Sohn, W; Merenda, A; Shafaghat, AH; Phuntsho, S; Gao, L; Shon, HK

Pilot-scale membrane bioreactor for source-separated urine: Impact of hydraulic retention time on fertiliser production

Sohn, W Merenda, A Shafaghat, AH Phuntsho, S

Gao, L Shon, HK

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Publisher:: ELSEVIER
Publication Type:: Journal Article
Citation:: Desalination, 2025, 616
Issue Date:: 2025-12-01

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Field	Value	Language
dc.contributor.author	Sohn, W
dc.contributor.author	Merenda, A
dc.contributor.author	Shafaghat, AH
dc.contributor.author	Phuntsho, S https://orcid.org/0000-0002-3917-3916
dc.contributor.author	Gao, L
dc.contributor.author	Shon, HK
dc.date.accessioned	2025-10-17T00:14:32Z
dc.date.available	2025-10-17T00:14:32Z
dc.date.issued	2025-12-01
dc.identifier.citation	Desalination, 2025, 616
dc.identifier.issn	0011-9164
dc.identifier.issn	1873-4464
dc.identifier.uri	http://hdl.handle.net/10453/190518
dc.description.abstract	Prolonged hydraulic retention time (HRT) in urine-treating membrane bioreactors (MBR) remains a challenge as it increases system footprint and costs. This study investigated the effects of HRT conditions in a pilot-scale compact MBR system on urine nitrification performance, aiming to determine the optimal HRT threshold ensuring the effectiveness of the produced liquid fertiliser on hydroponic plant growth. The start-up phase of the MBR successfully achieved stable nitrification at a 7-day HRT under pH-controlled feeding, with a high enrichment of Nitrospira as the predominant nitrite-oxidising bacteria (NOB) and Nitrosococcus as the dominant ammonia-oxidising bacteria (AOB). However, the transition to continuous urine feeding at systematically reducing HRTs of 5 days, 3 days, and 1 day resulted in a decreasing ammonia-to-nitrate conversion rate, dropping from 40 % to 10 % along with a significant nitrite accumulation caused by the high enrichment of AOB over NOB. The urine fertiliser produced under each HRT condition presented distinctive formulations, with a fixed total nitrogen concentration and varying nitrogen species proportions. The fertilisers were applied to hydroponic growth of basil and orchard grass. Both basil and orchard grass showed optimal growth, in terms of roots-to-shoots ratio, at HRTs of up to 5 days. However, orchard grass showed more resilience to the variations in HRT, displaying similar fresh biomass yields across the different conditions. This study offers valuable insights into optimising HRT in urine MBR systems to enhance nutrient recovery as a liquid fertiliser, paving the way for more compact and cost-efficient on-site nutrient recovery and fertiliser application at scale.
dc.language	English
dc.publisher	ELSEVIER
dc.relation	http://purl.org/au-research/grants/arc/IH210100001
dc.relation.ispartof	Desalination
dc.relation.isbasedon	10.1016/j.desal.2025.119388
dc.rights	info:eu-repo/semantics/openAccess
dc.subject	03 Chemical Sciences, 09 Engineering
dc.subject.classification	Chemical Engineering
dc.subject.classification	34 Chemical sciences
dc.subject.classification	40 Engineering
dc.title	Pilot-scale membrane bioreactor for source-separated urine: Impact of hydraulic retention time on fertiliser production
dc.type	Journal Article
utslib.citation.volume	616
utslib.for	03 Chemical Sciences
utslib.for	09 Engineering
pubs.organisational-group	University of Technology Sydney
pubs.organisational-group	University of Technology Sydney/Faculty of Engineering and Information Technology
pubs.organisational-group	University of Technology Sydney/Faculty of Engineering and Information Technology/School of Civil and Environmental Engineering
pubs.organisational-group	University of Technology Sydney/UTS Groups
pubs.organisational-group	University of Technology Sydney/UTS Groups/Centre for Technology in Water and Wastewater (CTWW)
utslib.copyright.status	open_access	*
dc.rights.license	This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0). To view a copy of this license, visit https://creativecommons.org/licenses/by/4.0/
dc.date.updated	2025-10-17T00:14:31Z
pubs.publication-status	Accepted
pubs.volume	616

Abstract:

Prolonged hydraulic retention time (HRT) in urine-treating membrane bioreactors (MBR) remains a challenge as it increases system footprint and costs. This study investigated the effects of HRT conditions in a pilot-scale compact MBR system on urine nitrification performance, aiming to determine the optimal HRT threshold ensuring the effectiveness of the produced liquid fertiliser on hydroponic plant growth. The start-up phase of the MBR successfully achieved stable nitrification at a 7-day HRT under pH-controlled feeding, with a high enrichment of Nitrospira as the predominant nitrite-oxidising bacteria (NOB) and Nitrosococcus as the dominant ammonia-oxidising bacteria (AOB). However, the transition to continuous urine feeding at systematically reducing HRTs of 5 days, 3 days, and 1 day resulted in a decreasing ammonia-to-nitrate conversion rate, dropping from 40 % to 10 % along with a significant nitrite accumulation caused by the high enrichment of AOB over NOB. The urine fertiliser produced under each HRT condition presented distinctive formulations, with a fixed total nitrogen concentration and varying nitrogen species proportions. The fertilisers were applied to hydroponic growth of basil and orchard grass. Both basil and orchard grass showed optimal growth, in terms of roots-to-shoots ratio, at HRTs of up to 5 days. However, orchard grass showed more resilience to the variations in HRT, displaying similar fresh biomass yields across the different conditions. This study offers valuable insights into optimising HRT in urine MBR systems to enhance nutrient recovery as a liquid fertiliser, paving the way for more compact and cost-efficient on-site nutrient recovery and fertiliser application at scale.

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