Japanese sewer authorities are now profitably mining sewage for gold.

A sewage treatment facility in central Japan has recorded a higher gold yield from sludge than can be found at some of the world’s best mines. An official in Nagano prefecture, northwest of Tokyo, said the high percentage of gold found at the Suwa facility was probably due to the large number of precision equipment manufacturers in the vicinity that use the yellow metal. The facility recently recorded finding 1,890 grammes of gold per tonne of ash from incinerated sludge.