ABSTRACT
In this chapter, the authors report measurements of contaminant removal by 11 wetlands constructed to treat coal mine drainage in western Pennsylvania. Contaminant concentrations decrease as water flows through constructed wetlands because of two distinct processes: contaminants are removed from solution by chemical and biological mechanisms, and contaminant concentrations are diluted by inputs of uncontaminated water. Contaminant removal at sites receiving alkaline mine water is unambiguously evaluated through calculation of iron and manganese removal rates because no undesirable dissolved by-products are associated with the removal of these metals in a buffered chemical environment. When mine water is acidic, wetland performance is best evaluated by calculation of acidity removal rates. Rates of acidity removal and alkalinity generation by sulfate reduction and calcium carbonate dissolution were calculated for four constructed wetlands that received acidic mine water. The contaminant removal rates reported are useful sizing criteria for the future construction of wetlands for the treatment of coal mine drainage.
