Human faeces contains gold, silver and other metals which
could be worth hundreds of millions of dollars, say scientists who are
investigating ways to extract the precious metals from poop. Treated solid
waste contains gold, silver and other metals, as well as other rare elements
such as palladium and vanadium that are used in electronics and alloys,
researchers have found.
"There are metals everywhere, in your hair care
products, detergents, even nanoparticles that are put in socks in order to
prevent bad odours," said Dr Kathleen Smith, from the United States
Geological Survey (USGS).
Whatever their origin, the wastes containing these metals
all end up being funnelled through wastewater treatment plants, where Smith
said many metals end up in the leftover solid waste.
At treatment plants, wastewater goes through a series of
physical, biological and chemical processes. The end products are treated water
and biosolids. Smith said more than seven million tonnes of biosolids come out
of American wastewater facilities each year. About half of that is used as
fertilizer on fields and in forests, while 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. 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 said that in a controlled setting,
they could safely be used to recover metals in treated solid waste.
So far, her group has collected samples from small towns in
the Rocky Mountains, rural communities and big cities. In the treated waste,
Smith's group has already started to discover metals like platinum, silver and
gold. She stated that they have observed microscopic-sized metal particles in
biosolids using a scanning electron microscope.
"The gold we found was at the level of a minimal
mineral deposit," she said, meaning that if that amount were in rock, it
might be commercially viable to mine it.
News Credit : http://timesofindia.indiatimes.com/home/science/
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