|Final Report – Sulfate-Reducing Bacteria Reactive Wall Demonstration, Mine Waste Technology Program, Activity III, Project 12 (EPA/600/R-02/053) June 2002
This document describes the demonstration of a passive technology that could be used for remediation of thousands of abandoned mine sites (located in the western United States) with acid mine drainage (AMD).
Passive remedial technology takes advantage of the ability of sulfate-reducing bacteria (SRB) to increase the pH and alkalinity of the water and to immobilize dissolved metals by precipitating them as metal sulfides or hydroxides. The SRB technology was demonstrated by constructing three bioreactors at an abandoned mine site (Calliope Mine) in the vicinity of Butte, Montana.
The bioreactors were fed by AMD from a large waste rock pile. The quality of this AMD and its pH are related to the amount of atmospheric water that infiltrates the pile and leaches metals. With the exception of the first eight months of operation, atmospheric precipitation was well below normal. Consequently, the pH of the AMD increased and the load of metals in the AMD significantly decreased, bringing concentrations of iron, aluminum, and manganese in the influent AMD below the target treatment levels for the project. The bioreactors operated from December 1998 to July 2001, when they were decommissioned.
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