Abstract: There are basically two kinds of biological passive treatment cells for treating mine drainage. Aerobic Cells, containing cattails and other plants, are typically applicable to coal mine drainage where iron and manganese and mild acidity are problematic. Anaerobic Cells or Sulfate-Reducing Bioreactors are typically applicable to metal mine drainage with high acidity and a wide range of metals. Most passive treatment systems employ one or both of these cell types. The track record of aerobic cells in treating coal mine drainage is impressive, especially in the eastern coalfields. Sulfate-reducing bioreactors have tremendous potential at metal mines and coal mines, but have not seen as wide an application. This paper presents the advantages of sulfate-reducing bioreactors in treating mine drainage, including: the ability to work in cold, high altitude environments, handle high flow rates of mildly affected ARD in moderate acreage footprints, treat low pH acid drainage with a wide range of metals and anions including uranium, selenium, and sulfate, accept acid drainagecontaining dissolved aluminum without clogging with hydroxide sludge, have life-cycle costs on the order of $0.50 per thousand gallons, and be integrated into “semi-passive” systems that might be powered by liquid organic wastes. Sulfate reducing bioreactors might not be applicable in every abandoned mine situation. However a phased design program of laboratory, bench, and pilot scale testing has been shown to increase the likelihood of a successful design.
