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Barton, C. D., & Karathanasis, A. D. (1997). Aerobic and anaerobic metal attenuation processes in a constructed wetland treating acid mine drainage. In AAPG Eastern Section and the Society for Organic Petrology joint meeting; abstracts (1545). 81: AAPG Bulletin.
Abstract: The use of constructed wetlands for acid mine drainage amelioration has become a popular alternative to conventional treatment methods, however, the metal attenuation processes of these systems are poorly understood. Precipitates from biotic and abiotic zones of a staged constructed wetland treating high metal load (approx. equal to 1000 mg L (super -1) ) and low pH (approx. 3.0) acid mine drainage were characterized by chemical dissolution, x-ray diffraction, thermal analysis and scanning electron microscopy. Characterization of abiotic/aerobic zones within the treatment system suggest the presence of crystalline iron oxides and hydroxides such as hematite, lepidocrocite, goethite, and jarosite. At the air/water interface of initial abiotic treatment zones, SO (sub 4) /Fe ratios were low enough (<2.0) for the formation of jarosite and goethite, but as the ratio increased due to treatment and subsequent reductions in iron concentration, jarosite was transformed to other Fe-oxyhydroxysulfates and goethite formation was inhibited. In addition, elevated pH conditions occurring in the later stages of treatment promoted the formation of amorphous iron oxyhydroxides. Biotic wetland cell substrate characterizations suggest the presence of amorphous iron minerals such as ferrihydrite and Fe(OH) (sub 3) . Apparently, high Fe (super 3+) activity, low Eh and low oxygen diffusion rates in the anaerobic subsurface environment inhibit the kinetics of crystalline iron precipitation. Some goethite, lepidocrocite and hematite, however, were observed near the surface in biotic areas and are most likely attributable to increased oxygen levels from surface aeration and/or oxygen transport by plant roots. Alkalinity generation from limestone dissolution within the substrate and bacterially mediated sulfate reduction also has a significant role on the mineral retention process. The formation of gypsum, rhodochrocite and siderite are by-products of alkalinity generating reactions in this system and may have an impact on S, Mn, and Fe solubility controls. Moreover, the buffering of acidity through excess alkalinity appears to facilitate the precipitation and retention of metals within the system.
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Wilmoth, R. C. (1973). Environmental Protection Agency, Technology Series Report. Washington: U.S. Government Print. Offfice.
Abstract: EPA 670 2 73 100 Spiral-wound reverse osmosis systems were tested on four different acid mine drainage discharges in west virginia and pennsylvania. Comparison studies were made of the hollow-fiber, tubular, and spiral-wound systems at a ferrous iron acid discharge; and of hollow-fiber and spiral-wound systems at a ferric iron acid discharge. At all sites, the limiting factor in high recovery operation was calcium sulfate insolubility. An empirical formula was developed for predicting maximum recovery. Application of reverse osmosis was demonstrated to be technically feasible for a large percentage of acid mine drainage discharges. A process called 'neutrolisis' was developed in which the reverse osmosis brine is neutralized and clarified, and the supernatant recycled to the influent to the reverse osmosis unit. In this manner, the neutrolosis process discharges only a high quality product water and a neutralized sludge. Neutrolosis recoveries as high as 98.8 percent were achieved at a ferric iron acid discharge site. (epa)
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Schueck, J. H. (1995). Limestone diversion wells; a low-maintenance, cost-effective method for treating acid-mine drainage with limestone. In C. R. Carnein, & J. H. Way (Eds.), Guidebook for the Annual Field Conference of Pennsylvania Geologists, vol.60 Applied geology in the Lock Haven and Williamsport region, Clinton and Lycoming counties, northcentral Pennsylvania (pp. 9–12).
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Bilek, F., Werner, F., & Schöpke, R. (2003). Experimentelle und modellgestützte Entwicklung von Verfahren zur geochemischen Grundwasser- und Untergrundbehandlung zur Gefahrenabwehr im Nordraum des Senftenberger Sees.544.
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Cravotta, C. A., III, Watzlaf, G. R., Naftz, D. L., Morrison, S. J., Fuller, C. C., & Davis, J. A. (2002). Design and performance of limestone drains to increase pH and remove metals from acidic mine drainage Handbook of groundwater remediation using permeable reactive barriers; applications to radionuclides, trace metals, and nutrients.. Amsterdam: Academic Press.
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