March 24, 2015
Mining gold from human feces: Yes, we’re serious
Somehow we think Goldmember will be singing a different tune after this.
According to new research just presented at the 249th national meeting of the American Chemical Society in Denver, there are enough gold particles in solid human waste that it would be profitable to mine municipal sewage facilities.
Sure, you jokingly refer to your toilet as “The Throne,” but who knew you were literally filling it with gold on a regular (hopefully) basis?
“The gold we found was at the level of a minimal mineral deposit," said study author Kathleen Smith, from the US Geological Survey (USGS).
"A minimal mineral deposit." We chuckled.
In addition to gold, USGS researchers also found significant amounts of silver and valuable rare earth metals, like palladium and vanadium. The study team also found substantial amount of harmful metals that they are interested in extracting from sewage for environmental reasons.
"There are metals everywhere," Smith said, "in your hair care products, detergents, even nanoparticles that are put in socks to prevent bad odors."
At sewage plants, wastewater undergoes a number of physical, biological and chemical operations. The end products are treated water and biosolids. Smith said over 7 million tons of biosolids emerged from American wastewater facilities annually. Approximately one half of that is used as fertilizer on fields and in forests, while the other 50 percent is incinerated or shipped to landfills.
Two-pronged, intense approach
Before you start thinking you’re suddenly flush with cash, the USGS team noted that extracting these metals is going to be a scientifically intensive process.
"We have a two-pronged approach," Smith said. "In one part of the study, we are looking at removing some regulated metals from the biosolids that limit their use for land application.”
"In the other part of the project, we're interested in collecting valuable metals that could be sold, including some of the more technologically important metals, such as vanadium and copper that are in cell phones, computers and alloys," she added.
The team said they are planning to follow the lead of industrial mining operations and are using chemicals called leachates to pull metals out of rock. Leachates do have a reputation for being toxic to ecosystems; however, Smith said in a controlled setting they be used to safely extract metals from waste.
Smith warned that "the economic and technical feasibility of metal recovery from biosolids needs to be evaluated on a case-by-case basis."