Surrounded by mining, the mountainous region of Potosi, Bolivia, is plagued by extensive environmental contamination from past and current mining operations. One mountain alone annually discharges an estimated 161 tons of zinc, 157 tons of iron, and more than two tons of arsenic in addition to dozens of other toxic minerals, including cadmium and lead, through its water. Researchers from the University of Oklahoma have discovered a technique to remove pollutants from water that requires minimal labor costs and is powered by nature itself. After 15 years of testing, research has shown this passive water treatment method to be successful in as diverse geography as the flatlands of Oklahoma and the mountains of Bolivia.
|OU researchers measure water quality in mine drainage flows in Bolivia.|
|Improved water quality is clearly visible at the Tar Creek site in Oklahoma.|
The passive water treatment system is created by engineering an ecosystem consisting of a series of filtering ponds. As the water moves through each specifically designed pond, a natural chemical or biological process removes certain contaminants as it slowly moves from one cell into the other before being re-released into natural waterways. “When the water reaches the last pond, it has gone from looking like orange, sediment-laden sludge to clear water,” said Robert Nairn, Associate Director for OU’s Water Technologies for Emerging Regions Center and director of the Center for Restoration of Ecosystems and Watersheds.
|Bolivian highland villagers depend upon surface water for drinking and cooking.|
The ecological filtering system requires less fossil fuel input and produces less pollution than traditional energy intensive water filtration technologies. “Since it is powered by the sun, wind and gravity, it requires minimal labor cost and only needs to be checked about once every three months,” said Nairn.
The passive water treatment system captures contaminated water from the mines, which flows through the series of constructed ponds for treatment. “The region gets less than 17 inches of rain per year,” Nairn said. “Much of the limited water is used for irrigation of staple root crops by the local farmers, resulting in contaminated soils and crops, posing substantial health risks.”
|Dr. Bob Nairn, OU WaTER Center Associate Director, teaches courses in ecological engineering and wetlands science.|
Building upon their experience in the Tar Creek, Okla., Superfund site, the researchers are engineering an ecosystem to treat polluted water in Potosi. The difference between the Tar Creek project and Potosi project is the extreme geographical conditions. Instead of Oklahoma flatlands, the team is working in a desert at 16,000 feet, which poses new challenges. “Massive water pollution is an issue that affects us all,” Nairn said. “If left untreated, the results are the same: unsafe living conditions and potential health risks. We learn from research in both developed and undeveloped countries to counteract this man-made threat with ecologically friendly solutions.”