<aside> 💡 People have had ideas to turn feces into charcoal, biogas, fertilizer, etc. but we wanted to see if we could also do something with urine. We've come up with a hypothesis to extract the ammonia gas from urine and have it react with sulphuric acid to create ammonium sulfate. Ammonium sulfate can then be sold at $66.64 USD/kg and profit can be made to incentive people to continue using the toilet.

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How We'll Turn Pee → Ammonium Sulfate…

Picture of what this could look like from a prior experiment done in Finland.

Picture of what this could look like from a prior experiment done in Finland.

  1. We take a 1L glass bottle and put 700mL of urine inside.
  2. We add 14 grams of calcium hydroxide (Ca(OH)2) to the 1L glass bottle to increase it's pH level to 12.
  3. We take two more glass bottles, connect them with airflow tubes, put 0.90mL of sulfiric acid into one & 0.90mL into the other, and add an air outlet on the second glass bottle.
  4. The urine bottle is then heated to 30 degrees Celsius to induce faster ammonia stripping and air is added to the 1L urine bottle using a ceramic diffuser that flows air in at a rate of 1100 - 1200 mL/min to strip the ammonia from the urine.
  5. The stripped ammonia is passed into the bottle with 0.90mL bottle and this reacts with the sulphuric acid we added in step 3 to create ammonium sulfate.
  6. Any excess byproducts are passed into the second bottle and will either react with the sulfuric acid to create ammonium sulfate or will exit through the air outlet.

How Much Ammonium Sulfate Will We Make & How Much $$$ Is This…

0.0576kg per person per month.


We know that with 700mL of urine we can make 24kg of a compound that is 89% hydrogen triammonium disulfate and 11% ammonium sulfate.

That means ~2.4kg is ammonium sulfate and since the calculation initially made within the paper above is in kg/m^3 that means we produce 2.4kg per m^3 of urine. I wanted to convert the m^3 to mL so it's easier for us to calculate things. Since 1m^3 is 1,000,000mL, this would mean we produce 2.4kg/1,000,000mL of pee and a person on average pees 24,000mL/month (800mL/day * 30 days) and if we do the cross multiplication this means we produce 0.0576kg per person per month of ammonium sulfate.

$3.838464 per person per month.


We know that 1kg of ammonium sulfate = $66.64 according to this and we produce 0.0576kg, so if we do the cross multiplication this means we're making $3.84 per person per month.

Costs Associated With This