The Rich Earth Institute in Brattleboro, Vermont, aims to shift how we think about our own waste. They want to “close the nutrient cycle” by using our urine to grow what we next consume.
Samantha Larson in National Geographic:
Today, most human waste in the U.S. flows down the pipes to a facility such as DC Water's Blue Plains Advanced Wastewater Treatment Plant, the largest facility of its kind in the world. Blue Plains receives an average of 370 million gallons of wastewater, 94 percent of which is from residential sources in the District of Columbia and parts of Maryland and Virginia. This includes what washes down the kitchen drain, fills up washing machines, and flushes down toilets.
Once at Blue Plains, it all goes through a multistage process in which it is passed from pool to pool of various hues of reddish brown, where the liquid is stirred, bubbled, fed to algae, and filtered until it is clean enough to get dumped back into the Potomac River.
Much of what this process is doing is removing nitrogen and phosphorous, elements that can be pollutants when too much of them get into our rivers and oceans. But they are also essential nutrients for plant growth—and thus, two of the basic components of fertilizer.
Most conventional farms invest in synthetic fertilizer, which requires energy to produce and is associated with many environmental problems of its own. But by separating out human urine before it gets to the wastewater plant, Rich Earth cofounder Kim Nace says they can turn it into a robust fertilizer alternative: a “local, accessible, free, sanitary source of nitrogen and phosphorous.”