Home About Browse Search
Svenska


Drying fresh human urine in magnesium-doped alkaline substrates: Capture of free ammonia, inhibition of enzymatic urea hydrolysis & minimisation of chemical urea hydrolysis

Vasiljev, Anastasija and Simha, Prithvi and Demissie, Natnael and Karlsson, Caroline and Randall, Dyllon G. and Vinnerås, Björn (2022). Drying fresh human urine in magnesium-doped alkaline substrates: Capture of free ammonia, inhibition of enzymatic urea hydrolysis & minimisation of chemical urea hydrolysis. Chemical Engineering Journal. 428 , 131026
[Research article]

[img] PDF
923kB

Abstract

Recycling urine can reduce the flux of reactive nitrogen in the environment. This paper presents a novel approach to recover all N (Ntot) from urine, including ammonia (TAN; about 5% of Ntot), which is usually volatilised when alkalised urine is dehydrated. As analytical methods for measuring N have a standard deviation of at least 5%, real fresh urine was fortified with ammonia (urineN) or ammonia and phosphate (urineNP) so that TAN comprised 10% of Ntot. The urine was then added to different magnesium-based alkaline substrates (MgO, Mg(OH)2, MgCl2 + Mg(OH)2) and dried at 38 C. Chemical speciation modelling suggested that, irrespective of the substrate, >98% of Ntot in urineNP was recovered and 86% of TAN was precipitated as struvite. Experimental results showed that < 90% of Ntot was recovered when urineNP was dried in MgO and Mg(OH)2, suggesting that no TAN was captured. However, all phosphorus and potassium and 93% (+/- 5%) of Ntot and 30% of TAN were recovered when urineNP was dried in MgCl2 + Mg(OH)2, as the [Mg]:[NH4]:[PO4] molar ratio of 1.69:1.14:1.0 in urine favoured formation of struvite. Overall, this study demonstrated that all ammonia excreted in real fresh urine (unfortified, TAN < 5% Ntot) can be captured if urine is dried in substrates containing 3.7 g MgCl2.6H2O L-1 or 2.2 g MgSO4 L-1, but no calcium. Ammonia can also be captured if fresh urine is saturated with MgO or Mg(OH)2 with high reactivity (<60 s citric acid test). If the drying substrate has pH > 10 throughout the treatment, urease enzyme-catalysed degradation of urea to ammonia is prevented, resulting in complete recovery of all nutrients. The end-product is a solid fertiliser containing 10-11% nitrogen, 1-2% phosphorus and 2-3% potassium.

Authors/Creators:Vasiljev, Anastasija and Simha, Prithvi and Demissie, Natnael and Karlsson, Caroline and Randall, Dyllon G. and Vinnerås, Björn
Title:Drying fresh human urine in magnesium-doped alkaline substrates: Capture of free ammonia, inhibition of enzymatic urea hydrolysis & minimisation of chemical urea hydrolysis
Series Name/Journal:Chemical Engineering Journal
Year of publishing :2022
Volume:428
Article number:131026
Number of Pages:9
Publisher:ELSEVIER SCIENCE SA
ISSN:1385-8947
Language:English
Publication Type:Research article
Article category:Scientific peer reviewed
Version:Published version
Copyright:Creative Commons: Attribution-Noncommercial-No Derivative Works 4.0
Full Text Status:Public
Subjects:(A) Swedish standard research categories 2011 > 2 Engineering and Technology > 208 Environmental Biotechnology > Water Treatment
Keywords:Alkaline Dehydration, Ammonia, Fertiliser, Resource recovery, Source separating Sanitation, Wastewater treatment
URN:NBN:urn:nbn:se:slu:epsilon-p-115052
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-p-115052
Additional ID:
Type of IDID
DOI10.1016/j.cej.2021.131026
Web of Science (WoS)000729860200005
ID Code:26759
Faculty:NJ - Fakulteten för naturresurser och jordbruksvetenskap
Department:(NL, NJ) > Dept. of Energy and Technology
Deposited By: SLUpub Connector
Deposited On:20 Jan 2022 09:25
Metadata Last Modified:16 May 2022 20:30

Repository Staff Only: item control page

Downloads

Downloads per year (since September 2012)

View more statistics

Downloads
Hits