Science Stats Environment Stinkin’ rich Sewage sludge carries loads of valuable metals MONEY FLUSH Millions of dollars’ worth of gold, silver and other expensive elements swirl down the drain and into sewage treatment plants. © jgroup/iStock Share this:EmailFacebookTwitterPinterestPocketRedditPrint By Beth Mole April 22, 2015 at 6:00 am Sewage may be a gold mine. Researchers have found that sewage entering municipal wastewater treatment plants teems with 58 valuable elements such as gold and copper. To dig up the soiled loot, researchers analyzed treated sewage samples from 94 sites around the country. Extracting the goods, however, would be a dirty job. $500 approximate value of elements in a metric ton of treated sewage sludge $13 million approximate value of a year’s worth of sewage from 1 million people Source: P. Westerhoff et al/Environmental Science & Technology 2015 Editor’s Note: This story was corrected May 4, 2015. The approximate value of elements in a metric ton of sewage sludge is $500, not $500 million.