'Passive Treatment' Cleans up Some of the Nastiest Water on the Planet
It's been called "The Mountain That Eats Men." Towering above the small Bolivian town of Potosí is a peak that has wrought human and environmental destruction for centuries because of the precious metals buried under the soil and stones.
All those years of extracting silver and zinc, among other precious commodities, have heavily contaminated the local drinking water with a toxic cocktail of roughly 161 tons of zinc, 157 tons of iron and more than two tons of arsenic per year, the folks over at Txchnologist report.
The picture is certainly bleak. But there's some hope: University of Oklahoma researchers are piloting a relatively inexpensive and natural clean up process to turn the toxic sludge into water usable for crop irrigation.
The project stands in stark contrast to typical bank-busting chemical and electric process that clean wastewater like the runoff from the Potosí mines.
“The big thing here is that we’re promoting natural processes to do the work, not engineering organisms or coming up with new chemicals,” Robert Nairn, director of the University of Oklahoma's Center for Restoration of Ecosystems and Watersheds, told Txchnologist. “It’s an attempt to marry ecology with engineering and design.”
Using a tiered system of collection pools, each tailored with minerals or organisms that help along the cleaning process, the system slowly pulls out the contaminants using clay, limestone, and organic compost. The water passes through a final wetlands area to filter out any large physical particles before it is ready for agricultural use.
With $75,000 and minimal energy needs that can be met with solar panels, the pilot project has successfully turned rust-colored wastewater clear.