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__NOTOC__<small-title />[[Image:Struvite.jpg|thumb|right|150px200px|A jar of Struvite]][[Image:urine collection.jpg|thumb|right|150px|Man collecting urine in jerrycans on his bicycle]]Urine is often used as a liquid fertilizer in rural areas due to its highly concentrated nutrient content. The main minerals required by plants are nitrogen, potassium and phosphorus. Urine contains roughly 80% of the nitrogen, 60% of the potassium and 55% of the phosphorus that humans excrete. While nitrogen is relatively easy to obtain from other sources, potassium and phosphorus are more scarce. The only readily available organic source of these is urine. However [[application Application of urineUrine]] is often unwanted since it is required in large volumes, is inconvenient to transport and has a bad odor. Also it cannot be applied through irrigation systems.
When urine is stored, a spontaneous reaction occurs, forming the precipitate: magnesium ammonium phosphate also known as struvite. However only 30-50% of the phosphate precipitates naturally. By reacting the urine with magnesium, over 90% of the phosphorus can be recovered. This can be filtered out and dried to produce a valuable powder fertilizer. The remaining effluent contains most of the urine’s nitrogen and potassium. Since there are no precipitates and can be applied to crops through irrigation systems.
Struvite can be produced locally using a locally manufactured reactor. Currently the capital costs of the reactor are quite high and it must be built by skilled workers, so struvite production is not economically viable in all communities. However research is still being done to improve designs of the reactor and develop low cost business models.
<br>
{{procontable | pro=
- It is a biological product and does not contain any heavy metals or pharmaceuticals <br>
}}
===History and social context===[[Image:urine collection.jpg|thumb|right|200px|Man collecting urine in jerrycans on his bicycle]]
Pilot studies were conducted by Eawag and UN-Habitat in a peri-urban farming community called Siddhipur in the Kathmandu Valley in Nepal. This was done to investigate the feasibility of urine separation and local struvite production.
The study showed that struvite recovery is indeed feasible and a community wide production programme could generate around 170kg of struvite per year.
===Suitable conditions ===Struvite production is basically suitable in areas where [[Application of Urine|urine application]] is possible. It requires the implementation of EcoSan systems in the community. It might have to be used in combination with other fertilizers, such as the effluent left when struvite is precipitated. This can be used in irrigation systems to directly fertilize crops.
Further for the business model to be sustainable, a local magnesium source is required.
===Technical specification===
====Operation====
[[Image:Struvite production.jpg|thumb|right|150px200px|Man operating struvite reactor]]For the production of struvite, firstly urine is needed. This can be collected from markets, urinals, public buildings. It must be separated from other sanitation products using [[Urine Diverting Dry Toilet|urine diverting toilets]] or other EcoSan technologies. Then magnesium must be obtained. This can come from bittern from salt production, which contains 3-10% magnesium, or magnesium sulphate from fertilizer powder, containing 5-10% magnesium.
Using the STUN reactor:
====Maintenance====
For the production of struvite it is necessary to manufacture a struvite harvesting reactor. This can be of different sizes depending on the scale of struvite production. The reactor and materials used can be adapted depending on the funds and materials available.
====Estimated Lifespan====
===Cost===
{{Treatment_Cost
* For a 500L reactor in Nepal.
==Country experiences=Manuals=== * [https://www.eawag.ch/fileadmin/Domain1/Abteilungen/eng/projekte/vuna/doc/Eawag_News_0115_e.pdf How to produce fertilizer from urine]
===References and External Links===* [https://www.eawag.ch/en/department/sandec/projects/faecal-sludge-quantification-and-characterisation/stun/ Eawag STUN project]{{Joinus}}* [https://www.eawag.ch/fileadmin/Domain1/Abteilungen/sandec/schwerpunkte/ewm/STUN/Struvite_pdfs/struvite_poster_nep.pdf Struvite Recovery in Kathmandu]
