Sunday 13 September 2009

Urine and Seawater Process

A valuable fertilizer called struvite can be produced by simply mixing seawater and urine.
I have made a pamphlet to describe the process for public knowledge. The process may be used to recycle phosphorous in new and existing urinals, with no major infrastructural changes. The process is extremely low-tech and simple and may be used around the world.














Click on the above image for an expanded view



Text:
Valuable Fertilizer from Urine and Seawater
Online September 13, 2009
K. Gell

Collection:
Men and women are able to comfortably urinate into an
odour-proof collection vessel, as shown in Figure 1.

Process:
Urea is hydrolyzed in the collection vessel. Seawater is
added at a volumetric ratio of 1 seawater to 4 urine.
Aeration and settling, each for 15 minutes followed by
decanting to a sewer or halophyte filter, produces 0.10
mm diameter crystals which are air dried, shown in
Figures 3 and 4.

Product:
Struvite is as effective as triple super phosphate as a
phosphorous fertilizer1,2, contains no pathogens3, very
low levels of metals3,6, hormones and pharmaceuticals4.

Background:
Struvite has been widely produced with urine5 and
separately with seawater6, but not both together. This
simple process has potential for new and existing toilets
in coastal areas around the world. It is the author’s
intent that this process be publicly known and used.

References:
(1) Ghosh, G.K., et al., Nutrient Cycling in Agroecosystems, 1996.
46(1): p. 71-79. (2) Johnston, A.E. and I.R. Richards. Soil Use and
Management, 2003. 19(1): p. 45-49. (3) Unpublished results, K. Gell
2009 (4) Escher, B.I., et al. Environmental Science & Technology,
2006. 40(16): p. 5095-5101. (5) Ronteltap, M., et al. Water Research,
2007. 41(5): p. 977-984. (6) Matsumiya, Y., et al. Water and
Environment Journal, 2000. 14(4): p. 291-296.

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