Waste not want not

摘要

Every year, humanity is flushing a fortune down the toilet (assuming you have a flushing toilet). Take the country with more flushing toilets per head of population than anywhere else -the USA. More than seven million tons of biosolids - treated sewage sludge - pass through US wastewater facilities annually and contained within it are surprisingly large quantities of silver, gold and platinum. But our days of wasting human waste may be numbered, if Kathleen Smith of the US Geological Survey has anything to say about it. She's leading a new research programme that's examining the feasibility of extracting precious metals from sewage. According to her, recovering metals from waste could reduce the need for environmentally-destructive mining programmes, and make biosolids a safer source of fertilizer to boot.