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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Brooks, R. P., Unz, R. F., Davis, L. K., Tarutis, W. J., & Yanchunas, J. (1990). Long-term removal and retention of iron and manganese from acidic mine drainage by wetlands.147.
Abstract: A promising low-technology solution for treating acidic mine drainage (AMD) emanating from coal mined lands involves the use of constructed wetlands.^The research was directed at addressing questions about retention mechanisms for the long-term storage of iron and manganese in constructed wetlands dominated by broad-leaved cattails (Typha latifolia).^Three sites in central Pennsylvania spanning the range of water chemistry parameters found in AMD were investigated.^When the AMD was circumneutral, and metal loadings were low, 79% of the iron, and 48% of the manganese were retained on average.^In the highly acidic site (pH approx.^= 3), < 10% of the metal loadings were retained.^The primary retention mechanism appears to be the formation of metal oxides in the aerobic zones of the sediments.^Although most microbial isolates extracted from sediment cores originated in the aerobic portions of the sediments, there was no evidence that they were transforming metals.^When AMD is circumneutral and metal loadings are low, constructed wetlands can be an effective approach to treating mine drainage.^At sites with highly acidic waters and high metal loadings, the use of constructed wetlands to treat AMD may be ineffectual, and should be implemented with caution.
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Brown, M., Barley, B., & Wood, H. (2002). Minewater Treatment – Technology, Application and Policy. London: IWA Publishing.
Abstract: Much work has been carried out in recent decades concerning minewater treatment, both in the UK and worldwide. Many different bodies and organizations are involved in developing minewater treatment processes and schemes. Minewater Treatment addresses the need for a single source of state-of-the-art information that draws all the latest research material together. Key features of the book include: a full literature review of minewater treatment throughout the world; an overview of relevant legislation and policy in a global context; a review of currently available methods for treating minewater worldwide; a site specific inventory of minewater treatment schemes within the UK, including compilation of available monitoring data and assessment of performance; a review of emerging and innovative minewater treatment technologies and consideration of related academic research within the UK; a comprehensive list of active and innovative minewater treatment technologies that are not currently compiled in a book or other review publication; a detailed summary and recommendations section assessing the applicability, efficiency and cost-effectiveness of minewater treatment schemes. Relevant scientific subject matter is presented in a concise, easily accessible manner to assist with the objective assessment of the progress made to date. Heavily illustrated with many colour photographs, the book allows best use to be made of the collective experience of minewater treatment practitioners throughout the UK, whilst at the same time placing the UK experience within a global context. An invaluable reference work for mining companies, consultants, planning officers, environmental research scientists, environmental agencies, water utilities and regulatory bodies, Minewater Treatment is a definitive source of information on minewater treatment technologies and will help facilitate the selection of the most appropriate technique required to tackle particular minewater discharge problems. Contents 1. The mine water problem 2. Treatment options 3. Existing sites in the UK: Case studies 4. Existing sites in the UK: Site summaries 5. Summary & conclusions
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Brown, M., Barley, B., & Wood, H. (2002). Minewater treatment; technology, application and policy. London: IWA Publishing.
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Brown, M. M., Atkinson, K., & Wilkins, C. (1994). Acid mine drainage amelioration by wetlands; study of a natural ecosystem. In Special Publication – United States. Bureau of Mines, Report: BUMINES-SP-06B-94 (406). Proceedings of the International land reclamation and mine drainage conference and Third international conference on The abatement of acidic drainage; Volume 2 of 4; Mine drainage.
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