An article in Nature discusses the recent discovery that human urine can be used as a valuable source of nutrients for plankton, which in turn are used as food for fish grown in fish farms. Here’s a bit from the article:
Human urine could nourish the plankton used as food on fish farms. Plankton grown in diluted urine do better than those given other nitrogen-rich materials, ecological engineers have found.
Bara Bihari Jana and his colleagues at the University of Kalyani, India, mixed ground water with human urine from the university’s urinals and added the zooplankton Moina micrura, which is often fed to hatchling fish in commercial fisheries.
They also tried rearing the plankton in various cocktails of cow urine, vermin compost, poultry droppings and cow dung, all of which are commonly used in fish farming in poor regions where chemical fertilizers are not available. All treatments used half a litre of urine, or half a kilo of dung, to every 4,500 litres of water.
Young plankton in human urine began reproducing at least four days earlier than those in other tanks, lived longer and produced more offspring, the researchers found. The study is published in Ecological Engineering.