Precious metals found in human waste could bring in revenue for cities

The American Chemical Society has come up with a way for cities to make up to $13 million a year. The catch? They have to sift through human waste in order to find valuable metals like gold, lead, and copper.

New research was presented at the ACS's national meeting that showed it might be worthwhile to go "mining" through biosolids, The Washington Post reports. In the United States, about 3.5 million tons of human waste is used every year to fertilize land, and a team led by Kathleen Smith of the U.S. Geological Survey was tasked with finding the best way to get metal particles out of the excrement in order to make the fertilizer work better. Then, Smith said, they realized that instead of tossing the metals, they could sell them: A city of 1 million people could produce $13 million worth of these metals annually.

Metals make their way into human waste via clothing and beauty, hygiene, and cleaning products, and Smith and her team are still trying to determine the best way to get the metals out. To make a real go of this, new procedures would have to be figured out and facilities built, but Smith says that on a case-by-case basis, extracting metals from poop could pay off.

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