Biodigester v18.01

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Nitrogen Ratio Calculations

  • 23:1 to 10:1 carbon to nitrogen ratio is acceptable in feedstocks - [1]. Nitrogen concentration of up to 5g/L are acceptable.
  • Peeing 10x and flushing with one gallon - 10 gallons of input can handle up to 200 g of nitrogen in that input, assuming adequate ratios of carbon were available.
  • Americans produce 90M gallons of urine per day, with 7M lb nitrogen. [2]. Per capita urine is thus 0.02 lb per day, or 9 grams. If urine is caught in a biodigester only during defecation, and other times it can be flushed separately, then only 1-2 grams of nitrogen would enter the biodigester per person from urination. This is fine for digester loading if the retention time of a 550 gallon digester is 60 days, or 10 gallons input per day. In the 10 gallon per day instance, human urine loading is only up to 0.2 g/gal per person, or 0.05 g/l. 5g/L is acceptable, so the human urine contribution in this scenario acceptable with a safety factor of 100.