Poop could be a goldmine — literally. Surprisingly, treated solid waste contains gold, silver and other metals, as well as rare elements such as palladium and vanadium that are used in electronics and alloys. Now researchers are looking at identifying the metals that are getting flushed and how they can be recovered. This could decrease the need for mining and reduce the unwanted release of metals into the environment.
“If you can get rid of some of the nuisance metals that currently limit how much of these biosolids we can use on fields and forests, and at the same time recover valuable metals and other elements, that’s a win-win,” says Kathleen Smith, who spearheaded this research.
In a recent Environmental Science & Technology paper, another research group also studying this issue calculated that the waste from 1 million Americans could contain as much as $13 million worth of metals. That’s $280 per ton of sludge. Shit, that’s a lot of money. One of the problems is that we have no idea what other valuables are in our poop. There is so much other shit in that shit that we don’t know about.
Smith and her team are on a mission to find out exactly what is in our waste. “We have a two-pronged approach,” she says. “In one part of the study, we are looking at removing some regulated metals from the biosolids that limit their use for land application.
“In the other part of the project, we’re interested in collecting valuable metals that could be sold, including some of the more technologically important metals, such as vanadium and copper that are in cell phones, computers and alloys,” Smith said. To do this, they are taking a page from the industrial mining operations’ method book and are experimenting with some of the same chemicals, called leachates, which this industry uses to pull metals out of rock. While some of these leachates have a bad reputation for damaging ecosystems when they leak or spill into the environment, Smith says that in a controlled setting, they could safely be used to recover metals in treated solid waste.
Are you collecting your poop now?
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