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Tarutis Jr, W. J., Stark, L. R., & Williams, F. M. (1999). Sizing and performance estimation of coal mine drainage wetlands. Ecological Engineering, 12(3-4), 353–372.
Abstract: The effectiveness of wetland treatment of acid mine drainage (AMD) was assessed using three measures of performance: treatment efficiency, area-adjusted removal, and first-order removal. Mathematical relationships between these measures were derived from simple kinetic equations. Area-adjusted removal is independent of pollutant concentration (zero-order reaction kinetics), while first-order removal is dependent on concentration. Treatment efficiency is linearly related to area-adjusted removal and exponentially related to first-order removal at constant hydraulic loading rates (flow/area). Examination of previously published data from 35 natural AMD wetlands revealed that statistically significant correlations exist between several of the performance measures for both iron and manganese removal, but these correlations are potentially spurious because these measures are derived from, and are mathematical rearrangements of, the same operating data. The use of treatment efficiency as a measure of performance between wetlands is not recommended because it is a relative measure that does not account for influent concentration differences. Area-adjusted removal accounts for mass loading effects, but it fails to separate the flow and concentration components, which is necessary if removal is first-order. Available empirical evidence suggests that AMD pollutant removal is better described by first-order kinetics. If removal is first-order, the use of area-adjusted rates for determining the wetland area required for treating relatively low pollutant concentrations will result in undersized wetlands. The effects of concentration and flow rate on wetland area predictions for constant influent loading rates also depend on the kinetics of pollutant removal. If removal is zero-order, the wetland area required to treat a discharge to meet some target effluent concentration is a decreasing linear function of influent concentration (and an inverse function of flow rate). However, if removal is first-order, the required wetland area is a non-linear function of the relative influent concentration. Further research is needed for developing accurate first-order rate constants as a function of influent water chemistry and ecosystem characteristics in order to successfully apply the first-order removal model to the design of more effective AMD wetland treatment systems.
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Perry, A., & Kleinmann, R. L. P. (1991). The use of constructed wetlands in the treatment of acid mine drainage. Natural Resources Forum, 15(3), 178–184.
Abstract: US government regulations require that all effluents from industrial operations, including mining, meet certain water quality standards. Constructed wetlands have proven to be useful in helping to attain those standards. Application of this biotechnology to mine water drainage can reduce water treatment costs and improve water quality in streams and rivers adversely affected by acidic mine water drainage from abandoned mines. Over 400 constructed wetland water treatment systems have been built on mined lands largely as a result of research by the US Bureau of Mines. Wetlands are passive biological treatment systems that are relatively inexpensive to construct and require minimal maintenance. Chemical treatment costs are reduced sufficiently to repay the cost of construction in less than a year. The mine waste water is typically treated in a series of excavated ponds that resemble small marsh areas. The ponds are engineered to facilitate bacterial oxidation of iron. Ideally, the water then flows through a composted organic substrate supporting a population of sulphate-reducing bacteria which raises the pH. Constructed wetlands in the US are described – their history, functions, construction methodologies, applicabilities, limitations and costs. -Authors
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Morfitt, B., Brewer, W., & Frobel, R. (1998). Cleaning up the Summitville Mine Superfund Site. Geotechnical Fabrics Report, 16(5), 38–41.
Abstract: A multi-layered geosynthetic system that includes geosynthetic-clay liners (GCL) and a geonet-composite drain (GNGC) is being used to cap and stabilize a 178000 m(exp 2) heap-leach pad at the Summitville Mine Superfund Site in Colorado. Selected were materials on the basis of design requirements for permeability, strength, extreme site conditions and cost. The Summitville cleanup called for a heap-leach pad cap to provide a barrier that would prevent precipitation from infiltrating the pad material. This long-term remediation prevents the pile from becoming saturated and allowing water to overflow the downslope dike, which could cause instability to dike and pond. Three geosynthetic alternatives were proposed. The contractor, that was awarded the heap leach pad, phase 2 contract, decided for a geosynthetic clay liner cap placed directly on the redesigned slopes. Bentofix NW-8 was used as GCL and TexNet TN was selected as the geocomposite drain. Conformance testing, subgrade preparation review, geosynthetic installation/repair inspection and review of cover material placement, performed by independent construction-quality assurance, showed that GCL is a well-suited cap material for heap leach pads, where high wind, cold temperatures rain and high altitude hinder construction. The robust geosynthetic allowed on-site coarse material to be used in the subgrade and cover layer, which saved the cost of importing more expensive bedding material.
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Wiessner, A., Kuschk, P., Buddhawong, S., Stottmeister, U., Mattusch, J., & Kästner, M. (2006). Effectiveness of various small-scale constructed wetland designs for the removal of iron and zinc from acid mine drainage under field conditions. Engineering in Life Sciences, 6(6), 584–592.
Abstract: A system of planted and implanted small-scale SSF (subsurface flow) and SF (surface flow) constructed wetlands together with HP (hydroponic systems) were installed to compare the removal efficiencies of Fe and Zn from AMD (acid mine drainage) under long-term field conditions. Maximum removal of 94 % – 97 % (116 mg/m(exp 2)/d – 142 mg/m(exp 2)/d) for Fe and 69 % – 77 % (6.2 mg/m(exp 2)/d – 7.9 mg/m(exp 2)/d) for Zn was calculated for the planted soil systems. The planted SSF was most sensitive to heavy rain fall. Short-term increases of the metal concentration in the outflows, short-term breakdowns of the Fe removal and continual long-term breakdowns of the Zn removal were observed. In contrast to Zn removal, all wetland types are applicable for Fe removal with maximum removal in the range of 60 % – 98 %. Most of the removed Fe and Zn was transformed and deposited inside the soil bed. The amount absorbed by the plants (0.03 % to 0.3 %) and gravel-associated soil beds (0.03 % to 1.7 %) of the total input were low for both metals. The response of the planted SSF to rainfall suggests a remobilisation of metals accumulated inside the rhizosphere and the importance of buffering effects of the surface water layers of SF systems. The importance of plants for metal removal was shown.
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Fischer, R., Luckner, L., Peukert, D., Reißig, H., & Roßbach, B. (2002). Einsatz alkalischer Substanzen zur Verbesserung der Wasserqualität in Bergbaukippen. Use of alcine substances for the improvement of water quality in mining areas. Das Gas und Wasserfach. Ausgabe Wasser, Abwasser, 143(12), 891–898.
Abstract: Eisendisulfidminerale im Abraum von Braunkohlentagebauen können nach ihrer Verwitterung im wiederaufsteigenden Grundwasser erhebliche Güteverschlechterungen hinsichtlich pH-Wert, Schwermetall- und Sulfatgehalt verursachen. Diesen kann durch Zusätze alkalischer Substanzen zum Abraum wie Kalkstein, Dolomit und Kraftwerksasche bzw. Gemischen dieser Stoffe entgegengewirkt werden. Die Ergebnisse entsprechender Untersuchungen sowie die naturwissenschaftlichen Grundlagen der Eisendisulfidverwitterung werden im Beitrag dargestellt und ein Anwendungsbeispiel beschrieben. Grundlagen zur Berechnung der einzusetzenden Kalk- oder Aschemengen (bzw. Gemische der beiden Substanzen) sind die Bestimmung der oxidierbaren Sulfidminerale in den einzelnen geologischen Schichten sowie die Bestimmung der Pufferkapazität der Asche bzw. des Kalksteins. Besonders Vorteilhaft ist der Einsatz alkalischer Substanzen dort, wo durch vorhandene hohe Pyrit- und Markasitkonzentrationen mit einer erheblichen Versauerung des Grundwassers gerechnet und dadurch eine potentielle Beeinträchtigung von Grundwassernutzern erwartet werden muss. Solche Bedingungen sind im Rheinischen Braunkohlerevier, insbesondere im Umfeld des Tagebaus Garzweiler II (RWE Rheinbraun AG) gegeben. Derzeit werden im Tagebau Garzweiler bereits 40000 t Kalkstein dem Abraum beigemischt. Auch für das Lausitzer Braunkohlenrevier könnte ein Einsatz alkalischer Substanzen in Betracht gezogen werden.
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