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> According to Simha’s estimates, humans produce enough urine to replace about one-quarter of current nitrogen and phosphorus fertilizers worldwide They have g

• danw1979 5y ago
  … but seriously, this astonished me. Would love to see the rough calculation behind this. My biochemistry isn’t nearly good enough to begin to replicate this estimate.
  • voxadam 5y ago
    Regardless of the biochem possibilities I wonder about the engineering realities required to collect, isolate, purify, and distribute the urea and other nitrogen rich compounds from the waste stream.
  • PeterisP 5y ago
    On a theoretical level, all these fertilizers get added just so the soil doesn't get depleted by what gets driven away to the field and eaten by city-dwelling humans, so it kind of makes sense that they get delivered to our bodies and then expelled.
• unfocussed_mike 5y ago
  > They have got to be taking the piss. The origin of this phrase (I am certain you know and merely detailing for others) is literally in the once-financially-viable business of collecting urine (from public houses, outdoor toilets, and even private houses) because it was a valuable source of ammonia before the invention of the (from memory, Haber-Bosch?) process for its industrial production.
  • Chris2048 5y ago
    It was notable that it was more than just "viable", but seriously protected (by nobility) because that ammonia was needed (and a limiting factor in) the production of gunpowder - hence it was a matter of security.