Yomiuri and Nagano Nippo are reporting that a sewage plant in Japan's Nagano prefecture has started mining gold from sewage sludge.
In the first month of mining the plant earnt 5 million yen ($56,000) from the gold they recovered. The sewage plant operator Nagano Prefecture Suwa Construction Office stated that they were able to recover around 1.9 kilograms (4.2 lbs) of gold from each ton of molten fly ash produced by the incineration of sludge.
The waste plant treats about 100,000 tons of wastewater every day. This generates around 3 tons of ash in the process.