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Old Mines, New Technology
By Ann Brown
New technology using tiny microbial organisms may be one part of the solution to treating water from old abandoned mines in the Western states.
These mines, many located in isolated areas and abandoned nearly a century ago, once provided the copper, zinc, lead, gold, and other metals used to fuel the nation's economy. Now the metal-laden water draining from the mines may be hazardous to humans when it flows into streams and rivers that supply municipal water systems. The high acidity and metals in the water can disrupt the delicate ecosystem, causing a detrimental impact on fish and other aquatic life and their habitat. Many of these mines have been designated as Superfund sites targeted for cleanup by the federal government.
"Because of the treatment costs, and the large number of abandoned mines and excessive amounts of waste materials, the only way these disturbed areas are going to be remediated is for all of us, including the academic world, industry and government, to work together," said David Reisman, director of the Engineering Technical Support Center in EPA's Office of Research and Development. "We must be innovative and creative in our approach, both scientifically and organizationally."
EPA scientists are participating in several demonstration projects of biochemical reactors which offer many advantages over standard water treatment plants at these remote mines at high elevations. The reactors do not require electricity because they operate based on gravitational forces, consequently, they are less costly to construct, operate, and maintain. Two of these reactors are located at a Superfund site in Helena, Montana. A demonstration project on another type of reactor using bacteria is being conducted near Markleeville, Calif., with BP Atlantic Richfield and the University of Nevada in Reno. The low-cost, low- maintenance systems use these tiny organisms to catalyze a biochemical process that has been shown to effectively remove metal contaminants from water drainage.
Earlier biochemical reactors had mechanical and operational challenges and often failed after three or four years. Researchers are working to develop a more efficient sustainable system. "I think we are moving into the second and third generation of biochemical reactors to treat mine drainage and in the future, we will find this is a viable technology for the remote areas," Reisman said.
At the Basin Creek Mine site near Helena, a biochemical reactor using manure as the source of the bacteria has been used effectively to treat almost one-half of the contaminated water collected from an onsite repository or pool. The reactor removed over 99 percent of the metals in the water during the 2005 and 2006 treatment seasons, effectively meeting EPA's and the State of Montana's water quality standards for metals.