Gold worth millions of dollars can be found in sewage sludge

Scientists have recently revealed that metals including gold, silver worth millions of dollars can be found in sewage sludge.

Scientists at Arizona State University stated that there could be as much as 13 million dollars worth of metals in the sludge produced by a city of one million people each year, including 2.6 million dollars in gold and silver.

Metals have long been known to concentrate in sewage, which mixes toilet water with effluent from industrial manufacturing, storm runoff, and anything else flushed down the drain. It's a headache for sewage utilities that must cope with toxic metals lacing wastewater headed for streams or sludge that might otherwise be spread on farm fields.

That amount won't be rattling the world gold market, nor would it be feasible to extract every last bit. But the study's lead author, environmental engineer Paul Westerhoff, said it could prove worthwhile for cities looking for ways to gain value from something that can be a costly disposal problem.

The researchers next plan to determine whether extracting metals is cost-effective or technically-viable.