It’s not uncommon to hear wastewater efficiency advocates refer to influent as a “resource” rather than “waste.” But it’s unlikely that any of them imagined just how valuable the material flushed through Swiss sewage systems really is.
According to a study from the Swiss Federal Office of the Environment, which surveyed 64 wastewater treatment plants across the country, an estimated 95 pounds of gold passes through local sewage systems every year.
“The lost gold is worth nearly $2 million at current prices,” CNN Money reported. “The researchers believe the tiny flecks of gold flow into the waste water system from the country’s famed watchmaking industry and gold refineries.”
As if that weren’t enough, the study also found that 6,600 pounds of silver goes through sewage pipes as well, at an estimated cost of $1.7 million.
Sadly, however, there doesn’t appear to be much opportunity to extract the precious metals from the sewage.
“Gold prospectors shouldn’t get too excited,” according to The Washington Post. “[The Swiss Federal Institute of Aquatic Science and Technology] warned that the concentration of gold in most places wasn’t high enough to financially justify mining the toxic sludge.”
But it isn’t just the Swiss who are sitting on a relative goldmine in their sewer pipes. A research effort found that the U.S. might be in a similar circumstance.
“Researchers from Arizona State University published a similar study in 2015, finding that a U.S. city of 1 million people flushes up to $13 million worth of precious metals into the sewage system each year,” per the Post. “Roughly $2.3 million of that is gold and silver.”
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Image credit: “100643169-gold-bars-pyramid-ap.1910x1000," everything all at once, 2017, used under an Attribution 2.0 Generic license: https://creativecommons.org/licenses/by/2.0/