Simha, Prithvi and Friedrich, Christopher and Randall, Dyllon Garth and Vinnerås, Björn
(2021).
Alkaline Dehydration of Human Urine Collected in Source-Separated Sanitation Systems Using Magnesium Oxide.
Frontiers in Environmental Science. 8
, 619901
[Research article]
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Abstract
Fresh human urine, after it is alkalized to prevent the enzymatic hydrolysis of urea, can be dehydrated to reduce its volume and to produce a solid fertilizer. In this study, we investigated the suitability of MgO to alkalize and dehydrate urine. We selected MgO due to its low solubility (<2 g.L-1) and relatively high saturation pH (9.9 +/- 0.2) in urine. Using a laboratory-scale setup, we dehydrated urine added to pure MgO and MgO mixed with co-substrates (biochar, wheat bran, or calcium hydroxide) at a temperature of 50 degrees C. We found that, dehydrating urine added to a mixture of MgO (25% w/w), biochar, and wheat bran resulted in a mass reduction of >90% and N recovery of 80%, and yielded products with high concentrations of macronutrients (7.8% N, 0.7% P and 3.9% K). By modeling the chemical speciation in urine, we also showed that ammonia stripping rather than urea hydrolysis limited the N recovery, since the urine used in our study was partially hydrolyzed. To maximize the recovery of N during alkaline urine dehydration using MgO, we recommend treating fresh/un-hydrolysed urine a temperature <40 degrees C, tailoring the drying substrate to capture NH4+ as struvite, and using co-substrates to limit the molecular diffusion of ammonia. Treating fresh urine by alkaline dehydration requires only 3.6 kg MgO cap(-1)y(-1) and a cost of US$ 1.1 cap(-1)y(-1). Therefore, the use of sparingly soluble alkaline compounds like MgO in urine-diverting sanitation systems holds much promise.
Authors/Creators: | Simha, Prithvi and Friedrich, Christopher and Randall, Dyllon Garth and Vinnerås, Björn | ||||||
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Title: | Alkaline Dehydration of Human Urine Collected in Source-Separated Sanitation Systems Using Magnesium Oxide | ||||||
Series Name/Journal: | Frontiers in Environmental Science | ||||||
Year of publishing : | 2021 | ||||||
Volume: | 8 | ||||||
Article number: | 619901 | ||||||
Number of Pages: | 9 | ||||||
Publisher: | FRONTIERS MEDIA SA | ||||||
ISSN: | 2296-665X | ||||||
Language: | English | ||||||
Publication Type: | Research article | ||||||
Article category: | Scientific peer reviewed | ||||||
Version: | Published version | ||||||
Copyright: | Creative Commons: Attribution 4.0 | ||||||
Full Text Status: | Public | ||||||
Subjects: | (A) Swedish standard research categories 2011 > 2 Engineering and Technology > 208 Environmental Biotechnology > Water Treatment | ||||||
Keywords: | ammonia, fertilizer, nitrogen recycling, urine source separation, wastewater, urine dehydration, sanitation, MgO | ||||||
URN:NBN: | urn:nbn:se:slu:epsilon-p-110779 | ||||||
Permanent URL: | http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-p-110779 | ||||||
Additional ID: |
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ID Code: | 22664 | ||||||
Faculty: | NJ - Fakulteten för naturresurser och jordbruksvetenskap | ||||||
Department: | (NL, NJ) > Dept. of Energy and Technology | ||||||
Deposited By: | SLUpub Connector | ||||||
Deposited On: | 25 Feb 2021 13:43 | ||||||
Metadata Last Modified: | 16 May 2022 20:37 |
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