Home About Browse Search
Svenska


Alkaline Urine Dehydration : how to dry source-separated human urine and recover nutrients?

Simha, Prithvi (2021). Alkaline Urine Dehydration : how to dry source-separated human urine and recover nutrients? Diss. (sammanfattning/summary) Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880
ISBN 978-91-7760-734-2
eISBN 978-91-7760-735-9
[Doctoral thesis]

[img] PDF
3MB

Abstract

Human urine is a renewable resource from which water, nutrients and energy can be recovered and safely recycled. This thesis presents a novel on-site technology, called alkaline dehydration, for recovering nutrients from source-separated urine.
To recover urea (the major nitrogenous compound in fresh urine) and prevent its urease enzyme-catalysed hydrolysis to ammonia, fresh urine was alkalised to pH ≥10 by anion exchange or use of alkaline substrates. To reduce the volume and concentrate the nutrients, the alkalised urine was dried in different substrates at temperatures of 40-60 °C. To evaluate alkaline urine dehydration at pilot-scale, a prototype dryer with capacity to treat 30 L urine d–1 was built and field-tested for three months at a military camp in Finland.
More than 90% of the urine mass was reduced and dehydration rates of up to 40 L urine d–1 m–2 were obtained. Up to 98% of the nitrogen (N) and 100% of the phosphorus (P) and potassium (K) in urine were recovered. A dry solid containing 10% N, 1.5% P and 6.0% K, with similar salt and heavy metal content to synthetic fertilisers available in Sweden was produced.
At least 12.5 g Ca(OH)2 or 6.8 g MgO per litre of fresh urine was required to buffer the pH of urine against absorption of CO2 during dehydration. The energy demand for evaporating urine was similar to that of incineration toilets, but could be reduced if heat energy from the dryer’s exhaust air were recovered.
Overall, this thesis shows that a new sanitation system that safely collects, treats, transports and applies urine as fertiliser could be created by integrating alkaline urine dehydration with existing infrastructure. If implemented globally, this system could recycle 31 Tg N y–1 and 2.8 Tg P y–1, which would reduce the transgression of the planetary boundary for N and P by 35% and 25%, respectively.

Authors/Creators:Simha, Prithvi
Title:Alkaline Urine Dehydration : how to dry source-separated human urine and recover nutrients?
Series Name/Journal:Acta Universitatis Agriculturae Sueciae
Year of publishing :2021
Number:2021:28
Number of Pages:91
Publisher:Department of Energy and Technology, Swedish University of Agricultural Sciences
ISBN for printed version:978-91-7760-734-2
ISBN for electronic version:978-91-7760-735-9
ISSN:1652-6880
Language:English
Publication Type:Doctoral thesis
Article category:Other scientific
Version:Published version
Full Text Status:Public
Subjects:(A) Swedish standard research categories 2011 > 2 Engineering and Technology > 207 Environmental Engineering > Other Environmental Engineering
(A) Swedish standard research categories 2011 > 2 Engineering and Technology > 201 Civil Engineering > Water Engineering
(A) Swedish standard research categories 2011 > 2 Engineering and Technology > 204 Chemical Engineering > Chemical Process Engineering
Keywords:circular bioeconomy, fertiliser, resource recovery, safe nutrient recycling, sanitation, source separation, urine diversion, wastewater treatment
URN:NBN:urn:nbn:se:slu:epsilon-p-111777
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-p-111777
ID Code:23473
Faculty:NJ - Fakulteten för naturresurser och jordbruksvetenskap
Department:(NL, NJ) > Dept. of Energy and Technology
Deposited By: SLUpub Connector
Deposited On:11 May 2021 13:03
Metadata Last Modified:14 May 2021 11:53

Repository Staff Only: item control page

Downloads

Downloads per year (since September 2012)

View more statistics

Downloads
Hits