Circa 2015 o.o!
If the holy grail of medieval alchemists was turning lead into gold, how much more magical would it be to draw gold from, well, poop? It turns out that a ton of sludge, the goo left behind when treating sewage, could contain several hundred dollars’ worth of metals—potentially enough to generate millions of dollars worth of gold, silver, and other minerals each year for a city of a million people.
Metals have long been known to concentrate in sewage, which mixes toilet water with effluent from industrial manufacturing, storm runoff, and anything else flushed down the drain. It’s a headache for sewage utilities that must cope with toxic metals lacing wastewater headed for streams or sludge that might otherwise be spread on farm fields.
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