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Cravotta, C.A., III; Trahan, M.K. |
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Title |
Limestone drains to increase pH and remove dissolved metals from acidic mine drainage |
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Journal Article |
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1999 |
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Appl. Geochem. |
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14 |
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5 |
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581-606 |
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manganese oxide redox processes sulfate waters iron-oxides adsorption ions oxidation surfaces environments aluminum |
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Abstract |
Despite encrustation by Fe and Al hydroxides, limestone can be effective for remediation of acidic mine drainage (AMD). Samples of water and limestone (CaCO3) were collected periodically for 1 a at 3 identical limestone-filled drains in Pennsylvania to evaluate the attenuation of dissolved metals and the effects of pH and Fe- and Al-hydrolysis products on the rate of CaCO3 dissolution. The influent was acidic and relatively dilute (pH < 4; acidity < 90 mg) but contained 1-4 mg . L-1 of O-2, Fe3+, Al3+ and Mn2+. The total retention time in the oxic limestone drains (OLDs) ranged from 1.0 to 3.1 hr. Effluent remained oxic (O-2 > 1 mg . L-1) but was near neutral (pH = 6.2-7.0); Fe and Al decreased to less than 5% of influent concentrations. As pH increased near the inflow, hydrous Fe and Al oxides precipitated in the OLDs, The hydrous oxides, nominally Fe(OH)(3) and Al(OH)(3), were visible as loosely bound, orange-yellow coatings on limestone near the inflow. As time elapsed, Fe(OH)(3) and Al(OH)(3) particles were transported downflow. The accumulation of hydrous oxides and elevated pH (> 5) in the downflow part of the OLDs promoted sorption and coprecipitation of dissolved Mn, Cu, Co, Ni and Zn as indicated by decreased concentrations of the metals in effluent and their enrichment relative to Fe in hydrous-oxide particles and coatings on limestone. Despite thick (similar to 1 mm) hydrous-oxide coatings on limestone near the inflow, CaCO3 dissolution was more rapid near the inflow than at downflow points within and the OLD where the limestone was not coated. The high rates of CaCO3 dissolution and Fe(OH3) precipitation were associated with the relatively low pH and high Fe3+ concentration near the inflow. The rate of CaCO3 dissolution decreased with increased pH and concentrations of Ca2+ and HCO3- and decreased Pco(2). Because overall efficiency is increased by combining neutralization and hydrolysis reactions, an OLD followed by a settling pond requires less land area than needed for a two-stagetreatment system consisting of an anoxic limestone drain and oxidation-settling pond or wetland. To facilitate removal of hydrous-oxide sludge, a perforated-pipe subdrain can be installed within an OLD. (C) 1999 Elsevier Science Ltd. |
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0883-2927 |
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Jul; Limestone drains to increase pH and remove dissolved metals from acidic mine drainage; Isi:000080043300004; file:///C:/Dokumente%20und%20Einstellungen/Stefan/Eigene%20Dateien/Artikel/10102.pdf; AMD ISI | Wolkersdorfer |
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CBU @ c.wolke @ 17470 |
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22 |
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Conca, J.L.; Wright, J. |
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An Apatite II permeable reactive barrier to remediate groundwater containing Zn, Pb and Cd |
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Journal Article |
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Year |
2006 |
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Appl. Geochem. |
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21 |
Issue |
12 |
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2188-2200 |
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Pollution and waste management non radioactive Groundwater quality apatite groundwater remediation zinc lead cadmium acid mine drainage copper sulfate nitrate permeability water treatment precipitation chemistry |
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Phosphate-induced metal stabilization involving the reactive medium Apatite II(TM) [Ca10-xNax(PO4)6-x(CO3)x(OH)2], where x < 1, was used in a subsurface permeable reactive barrier (PRB) to treat acid mine drainage in a shallow alluvial groundwater containing elevated concentrations of Zn, Pb, Cd, Cu, SO4 and NO3. The groundwater is treated in situ before it enters the East Fork of Ninemile Creek, a tributary to the Coeur d'Alene River, Idaho. Microbially mediated SO4 reduction and the subsequent precipitation of sphalerite [ZnS] is the primary mechanism occurring for immobilization of Zn and Cd. Precipitation of pyromorphite [Pb10(PO4)6(OH,Cl)2] is the most likely mechanism for immobilization of Pb. Precipitation is occurring directly on the original Apatite II. The emplaced PRB has been operating successfully since January of 2001, and has reduced the concentrations of Cd and Pb to below detection (2 μg L-1), has reduced Zn to near background in this region (about 100 μg L-1), and has reduced SO4 by between 100 and 200 mg L-1 and NO3 to below detection (50 μg L-1). The PRB, filled with 90 tonnes of Apatite II, has removed about 4550 kg of Zn, 91 kg of Pb and 45 kg of Cd, but 90% of the immobilization is occurring in the first 20% of the barrier, wherein the reactive media now contain up to 25 wt% Zn. Field observations indicate that about 30% of the Apatite II material is spent (consumed). |
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Dec.; An Apatite II permeable reactive barrier to remediate groundwater containing Zn, Pb and Cd; Science Direct |
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CBU @ c.wolke @ 17248 |
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44 |
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Bamforth, S.M. |
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Title |
Manganese removal from mine waters – investigating the occurrence and importance of manganese carbonates |
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Journal Article |
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2006 |
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Appl. Geochem. |
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21 |
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8 |
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1274-1287 |
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mine water treatment |
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Manganese is a common contaminant of mine water and other waste waters. Due to its high solubility over a wide pH range, it is notoriously difficult to remove from contaminated waters. Previous systems that effectively remove Mn from mine waters have involved oxidising the soluble Mn(II) species at an elevated pH using substrates such as limestone and dolomites. However it is currently unclear what effect the substrate type has upon abiotic Mn removal compared to biotic removal by in situ micro-organisms (biofilms). In order to investigate the relationship between substrate type, Mn precipitation and the biofilm community, net-alkaline Mn-contaminated mine water was treated in reactors containing one of the pure materials: dolomite, limestone, magnesite and quartzite. Mine water chemistry and Mn removal rates were monitored over a 3-month period in continuous-flow reactors. For all substrates except quartzite, Mn was removed from the mine water during this period, and Mn minerals precipitated in all cases. In addition, the plastic from which the reactor was made played a role in Mn removal. Manganese oxyhydroxides were formed in all the reactors; however, Mn carbonates (specifically kutnahorite) were only identified in the reactors containing quartzite and on the reactor plastic. Magnesium-rich calcites were identified in the dolomite and magnesite reactors, suggesting that the Mg from the substrate minerals may have inhibited Mn carbonate formation. Biofilm community development and composition on all the substrates was also monitored over the 3-month period using denaturing gradient gel electrophoresis (DGGE). The DGGE profiles in all reactors showed no change with time and no difference between substrate types, suggesting that any microbiological effects are independent of mineral substrate. The identification of Mn carbonates in these systems has important implications for the design of Mn treatment systems in that the provision of a carbonate-rich substrate may not be necessary for successful Mn precipitation. (c) 2006 Elsevier Ltd. All rights reserved. |
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Manganese removal from mine waters – investigating the occurrence and importance of manganese carbonates; Wos:000240297600004; Times Cited: 0; ISI Web of Science |
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CBU @ c.wolke @ 16916 |
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107 |
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