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Kleinmann, R. L. P. (1990). Acid Mine Water Treatment using Engineered Wetlands. Int. J. Mine Water, 9(1-4), 269–276.
Abstract: 400 systems installed within 4 years During the last two decades, the United States mining industry has greatly increased the amount it spends on pollution control. The application of biotechnology to mine water can reduce the industry's water treatment costs (estimated at over a million dollars a day) and improve water quality in streams and rivers adversely affected by acidic mine water draining from abandoned mines. Biological treatment of mine waste water is typically conducted in a series of small excavated ponds that resemble, in a superficial way, a small marsh area. The ponds are engineered to first facilitate bacterial oxidation of iron; ideally, the water then flows through a composted organic substrate that supports a population of sulfate-reducing bacteria. The latter process raises the pH. During the past four years, over 400 wetland water treatment systems have been built on mined lands as a result of research by the U.S. Bureau of Mines. In general, mine operators find that the wetlands reduce chemical treatment costs enough to repay the cost of wetland construction in less than a year. Actual rates of iron removal at field sites have been used to develop empirical sizing criteria based on iron loading and pH. If the pH is 6 or above, the wetland area (in2) required is equivalent to the iron. load (grams/day) divided by 10. Theis requirement doubles at a pH of 4 to 5. At a pH below 4, the iron load (grams/day) should be divided by 2 to estimate the area required (in2).
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Skousen, J. G. (1991). Anoxic limestone drains for acid mine drainage treatment. Green Lands, 21(4), 30–35.
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Michaud, L. H. (1994). Recent technology related to the treatment of acid drainage. Earth and Mineral Sciences, 63(3), 53–55.
Abstract: The generation of acid mine drainage is a serious environmental problem associated with coal mining. The chemistry of acid mine drainage is outlined. The prevention and minimization of acid mine drainage formation is examined. The in situ inhibition and remediation of acid mine drainage is described. Methods for the passive treatment of acid mine drainage after formation are discussed. The design of treatment systems is considered. -P.M.Taylor
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Eger, P. (1994). Wetland Treatment for Trace-metal Removal from Mine Drainage – the Importance of Aerobic and Anaerobic Processes. Water Sci. Technol., 29(4), 249–256.
Abstract: When designing wetland treatment systems for trace metal removal, both aerobic and anaerobic processes can be incorporated into the final design. Aerobic processes such as adsorption and ion exchange can successfully treat neutral drainage in overlandflow systems. Acid drainage can be treated in anaerobic systems as a result of sulfate reduction processes which neutralize pH and precipitate metals.Test work on both aerobic and anaerobic systems has been conducted in Minnesota. For the past three years, overland flow test systems have successfully removed copper, cobalt, nickel and zinc from neutral mine drainage. Nickel, which is the major contaminant, has been reduced around 90 percent from 2 mg/L to 0.2 mg/L. A sulfate reduction system has successfully treated acid mine drainage for two years, increasing pH from 5 to over 7 and reducing concentrations of all metals by over 90 percent.Important factors to consider when designing wetlands to remove trace metals include not only the type of wetlandrequired but also the size of the system and the residence time needed to achieve the water quality standards.
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Gusek, J. J. (1995). Passive-treatment of acid rock drainage: what is the potential bottom line? Min. Eng., 47(3), 250–253.
Abstract: Passive-treatment systems that mitigate acid-rock drainage from coal mines have been operating since the mid-1980s. Large systems at metal mines are being contemplated. A typical man-made passive-treatment-system can mimic a natural wetland by employing the same geochemical principles. Passive-treatment systems, however, are engineered to optimize the biogeochemical processes occurring in a natural wetland ecosystem. The passive-treatment methodology holds promise over chemical neutralization because large volumes of sludge are not generated. Metals may be precipitated as oxides, sulfides or carbonates in the passive-treatment system substrate. The key goal of a passive-treatment system is the long-term immobilization of metals in the substrate materials. The passive-treatment technique may not be applicable in all mine-drainage situations. -from Author
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