Monday, July 2, 2007
Waste Equals Food
In the Cradle to Cradle concept, where all of life operates on the basis of cyclical processes, we hear the phrase "waste equals food". Everything we create should in turn fuel the next cycle, and in this equation there is no end product, no grave.
Ecological engineer Bara Bihari Jana and his colleagues at the University of Kalyani, India, have discovered a new use for a waste we have in abundance- human urine. Commercial fisheries grow enormous amounts of Moina micrura, a zooplankton species commonly fed to hatchling fish in fisheries. The most common diet for these zooplankton is chemical fertilizers. But these fertilizers are expensive and not readily available in all countries. Jana initially tested poultry and cow dung for potential alternatives, and these showed promise. But when these microorganisms were fed a diet of human urine, they reproduced more quickly, lived longer and reproduced more offspring.
Because human urine starts out in solution and is stable in its original form, this makes it a very cheap alternative for the fish industry. This method could prove a viable means of treating our waste products without chemicals, and in turn return that product back into the food cycle.
Humans waste has so far not been readily used as an agricultural product, due to residual antibiotics and risk of disease transfer. "New and alternative uses for wastes and wastewater like this need to be identified," says Stephen Smith, an environmental biochemist at Imperial College London. "My only potential concern would be that the urine is from healthy individuals not taking medication or antibiotics as these could be excreted in the urine."
Jana and his colleagues are very aware of the risks of contamination by human waste, but so far have not encountered any of those problems with their zooplankton in their early lab tests.
For the original article in Nature