I've been thinking about food supplies, waste management and sustainable living, particularly in highly isolated areas like a Mars colony or a space station, or also in a non-technically advanced situation like urban survival during a major emergency.
One of the major things preventing human urine from being drinkable is the prescence of urea.
An adult supposedly excretes 25 grams of urea per day.
What chemicals (and in what quantities) would be needed to turn this amount of human urea into:
- a non-toxic, but non-nutritional ingestible substance?
- a nutritional substance?
I am thinking specifically about how to simply add a tablet/capsule to urine and having a nutritionally viable drink within 60 seconds or so.