MINE FOR GOLD
Talk about turning trash to treasure: scientists are looking at ways to extract precious metals – including gold, silver, platinum, copper and titanium – from sewage. What’s more, the amount is far from insubstantial: the waste produced by a million Americans every year could contain as much as US$13m worth of metals.[caption id="attachment_130" align="aligncenter" width="687"] Microscopic particles of gold and lead (yellow flecks) in a biosolid sample. The metals may come from various sources, including dental amalgams, food and cosmetics (pictured below)[/caption]
According to Dr Paul Westerhoff from Arizona State University, it’s unclear exactly where these metals are coming from because municipal sewage derives from more than just domestic origins. Waste from dentists’ offices is one likely trove because gold and silver is used in dental amalgams, while other potential sources are the cosmetics and personal care products that go down the drains. But poo could also be serving up the goods: titanium dioxide, for example, is added to many doughnuts.