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Open AccessArticle

Self-Powered Bioelectrochemical Nutrient Recovery for Fertilizer Generation from Human Urine

1
Advanced Water Management Centre, The University of Queensland, St. Lucia, QLD 4072, Australia
2
Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino (TO), Italy
3
Faculty of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573, Japan
*
Author to whom correspondence should be addressed.
Sustainability 2019, 11(19), 5490; https://doi.org/10.3390/su11195490
Received: 21 July 2019 / Revised: 26 September 2019 / Accepted: 1 October 2019 / Published: 3 October 2019
(This article belongs to the Special Issue Water-Energy Sustainable Urban Development)
Nutrient recovery from source-separated human urine has been identified by many as a viable avenue towards the circular economy of nutrients. Moreover, untreated (and partially treated) urine is the main anthropogenic route of environmental discharge of nutrients, most concerning for nitrogen, whose release has exceeded the planet’s own self-healing capacity. Urine contains all key macronutrients (N, P, and K) and micronutrients (S, Ca, Mg, and trace metals) needed for plant growth and is, therefore, an excellent fertilizer. However, direct reuse is not recommended in modern society due to the presence of active organic molecules and heavy metals in urine. Many systems have been proposed and tested for nutrient recovery from urine, but none so far has reached technological maturity due to usually high power or chemical requirements or the need for advanced process controls. This work is the proof of concept for the world’s first nutrient recovery system that powers itself and does not require any chemicals or process controls. This is a variation of the previously proposed microbial electrochemical Ugold process, where a novel air cathode catalyst active in urine conditions (pH 9, high ammonia) enables in situ generation of electricity in a microbial fuel cell setup, and the simultaneous harvesting of such electricity for the electrodialytic concentration of ionic nutrients into a product stream, which is free of heavy metals. The system was able to sustain electrical current densities around 3 A m–2 for over two months while simultaneously upconcentrating N and K by a factor of 1.5–1.7. View Full-Text
Keywords: bioelectrochemical system; urine; nutrient recovery; microbial fuel cell (MFC); air cathodes bioelectrochemical system; urine; nutrient recovery; microbial fuel cell (MFC); air cathodes
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Freguia, S.; Logrieco, M.E.; Monetti, J.; Ledezma, P.; Virdis, B.; Tsujimura, S. Self-Powered Bioelectrochemical Nutrient Recovery for Fertilizer Generation from Human Urine. Sustainability 2019, 11, 5490.

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