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?…In a new study, scientists at Arizona State University (ASU), Tempe, quantified the different metals in sewage sludge and estimated what it all might be worth. They took sludge samples gathered from around the country and measured the metal content using a mass spectrometer that can discern different elements as they are ionized in a superhot plasma. The upshot: There’s as much as $13 million worth of metals in the sludge produced every year by a million-person city, including $2.6 million in gold and silver, they report online this week in Environmental Science & Technology.

Warren Cornwall, Sewage sludge could contain millions of dollars worth of gold https://www.science.org/content/article/sewage-sludge-could-contain-millions-dollars-worth-gold 16 JAN 2015