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Baker, K. A., Fennessy, M. S., & Mitsch, W. J. (1991). Designing wetlands for controlling coal mine drainage: an ecologic- economic modelling approach. Ecological Economics, 3(1), 1–24.
Abstract: 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 wetland site and verified from multi-site data from Tennessee and Alabama. 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 “SUP -2” day “SUP -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. -Authors
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Ye, Z. H., Whiting, S. N., Qian, J. H., Lytle, C. M., Lin, Z. Q., & Terry, N. (2001). Trace element removal from coal ash leachate by a 10-year-old constructed wetland. J. Environ. Qual., 30(5), 1710–1719.
Abstract: This study investigated the ability of a 10-yr-old constructed wetland to treat metal-contaminated leachate emanating from a coal ash pile at the Widows Creek electric utility, Alabama (USA). The two vegetated cells, which were dominated by cattail (Typha latifolia L.) and soft rush (Juncus effusus L.), were very effective at removing Fe and Cd from the wastewater, but less efficient for Zn, S, B, and Mn. The concentrations were decreased by up to 99% for Fe, 91% for Cd, 63% for Zn, 61% for S, 58% for Mn, and 50% for B. Higher pH levels (>6) in standing water substantially improved the removing efficiency of the wetland for Mn only. The belowground tissues of both cattail and soft rush had high concentrations of all elements; only for Mn, however, did the concentration in the shoots exceed those in the belowground tissues. The concentrations of trace elements in fallen litter were higher than in the living shoots, but lower than in the belowground tissues. ne trace element accumulation in the plants accounted for less than 2.5% of the annual loading of each trace element into the wetland. The sediments were the primary sinks for the elements removed from the wastewater. Except for Mn, the concentrations of trace elements in the upper layer (0-5 cm) of the sediment profile tended to be higher than the lower layers (5-10 and 10-15 cm). We conclude that constructed wetlands are still able to efficiently remove metals in the long term (i.e., >10 yr after construction).
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