Incorporation of Bacterial Sulfate Reduction Into Constructed Wetlands for the Treatment of Acid and Metal Mine Drainage.
McIntire-PE; Edenborn-HM; Hammack-RW
Proceeds 1990 :207-213
The ecological impact of acid rain and acid mine drainage (AMD) on freshwater ecosystems has been shown to be lessened by naturally occurring bacterial sulfate reduction. Sulfate reduction proceeds only in the absence of oxygen and in the presence of sufficient organic carbon and sulfate. The net byproducts of sulfate reduction, hydrogen sulfide and bicarbonate, can precipitate metal sulfides and neutralize acidic water, respectively. Wetlands have been constructed at over 300 sites in the United States to treat AMD; these wetlands primarily remove iron via oxidative processes. An experimental wetland was designed and built by the U.S. Bureau of Mines to use sulfate reduction in the treatment of AMD by inducing water flow through anaerobic organic substrate. Bacterial sulfate reduction rates in the organic substrate of this wetland ranged from 2 to 600 nmol cm-3 day-1; these rates are comparable to those measured in coastal marine systems and are high enough to significantly affect the water quality of AMD. Iron concentrations decreased, ph increased, and alkalinity increased when the mine drainage was first forced through the anaerobic zone. This improvement in water quality was due to both the inherent chemical characteristics of the organic substrate and the bacterial activity. No improvement in water quality was observed after the AMD had been forced through the substrate for several weeks; this was apparently due to the exhaustion of the alkalinity present in the substrate by high AMD flow rates.
Proceeds, 1990 Nat'l Symp. on Mining, Lexington, Kentucky, 5/14-18/90. Univ. Kentucky, PP. 207-213