US researchers are investigating ways to extract the gold and precious metals from human faeces..Details were outlined at the 249th national meeting of the American Chemical Society (ACS) in Denver…The team estimates that seven million tonnes of solid waste come out of US wastewater facilities each year. About half of that is used as fertiliser on fields and in forests, while the other half is incinerated or sent to landfills. The scientists are experimenting with some of the same chemicals, called leachates, which industrial mining operations use 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 says that in a controlled setting – they could safely be used to recover metals in treated solid waste. In a previous study, another team of scientists calculated that the waste from one million Americans could contain as much as $13m (£8.6m) worth of metals.

BBC Gold in faeces ‘worth millions’ https://www.bbc.com/news/science-environment-32026636 23 March 2015