"The
gold we found was at the level of a minimal mineral deposit," said
Kathleen Smith, of the US Geological Survey, after her team discovered
metals such as platinum, silver and gold in treated waste.
A
recent study by another group of experts in the field found that waste
from one million Americans could contain as much as $13 million worth of
metals.
Finding a way to
extract the metals could help the environment by cutting down on the
need for mining and reducing 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," said
Smith.
"There are metals
everywhere -- in your hair care products, detergents, even nanoparticles
that are put in socks to prevent bad odors."
More
than seven million tons of biosolids come out of US wastewater
facilities each year: about half is used as fertilizer on fields and in
forests and the other half is incinerated or sent to landfills.
Smith and her team are on a mission to find out exactly what is in our waste.
"We
have a two-pronged approach," said Smith. "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."
The
findings were presented at the 249th National Meeting & Exposition
of the American Chemical Society (ACS), the world's largest scientific
society, taking place in Denver through Thursday.
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