Designing wetlands for controlling coal mine drainage: an ecologic-economic modelling approach
A simulation model is developed of the efficiency and economics of an application of ecotechnology — using a created wetland to receive and treat coal mine drainage. The model examines the role of loading rates of iron on treatment efficiencies and the economic costs of wetland versus conventional treatment of mine drainage. It is calibrated with data from an Ohio, U.S.A., wetland site and verified from multi-site data from Tennessee and Alabama, U.S.A. The model predicts that iron removal is closely tied to loading rates and that the cost of wetland treatment is less than that of conventional for iron loading rates of approximately 20–25 g Fe m−2 day−1 and removal efficiencies less than 85%. A wetland to achieve these conditions would cost approximately US$50 000 per year according to the model. When higher loading rates exist and higher efficiencies are needed, wetland systems are more costly than conventional treatment.