Plant officials at a sewage treatment plant in Japan say they have found about 2 mg per metric ton of the ash that remains after incinerating sludge — this is about 50 times as much gold than what’s found at Japan’s Hishikari Mine, one of the world’s largest gold mines.
The officials said the gold makes its way into the sewers because manufacturers use gold when making certain precision instruments. The big question is, could the same gold be found in sewage treatment plants across the world? And if so, can we start recycling the gold we have and stop mining — or at least stop opening new mines?
“In Northern Sulawesi, Indonesia, the Minahasa Raya gold mine, which the US-based Newmont Corporation opened in 1996 and closed in late 2003, discarded more than 4 million tons of tailings into the nearby Buyat bay, Local people reported skin rashes after contact with seawater and a toxicologist has found heavy metals in fish and plankton.”
In addition, many mines use a technique called “heap leaching” which exposes gold by dripping cyanide over mounds of ore:
This method of producing gold is cost effective but enormously wasteful: 99.99 percent of the heap becomes waste. To cut costs, the heaps are often abandoned. Gold mining areas are frequently studded with these immense, toxic piles, some of them reaching heights of 100 meters (over 300 feet), nearly the height of a 30-story building, and can take over entire mountainsides.
So while incinerating sludge is surely not fantastic for the environment, perhaps it would be worthwhile to test out similar processes at other sewage treatment plants in industrial areas — especially if it decreases the demand for new gold mines.
In the meantime, look for jewelry from one of these retailers who have agreed to No Dirty Gold’s list of “Golden Rules,” or better yet, look for vintage jewelry.
Photo Credit: jurvetson on Flickr under Creative Commons license.