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Author (up) Cravotta, C.A., III; Trahan, M.K.
Title Limestone drains to increase pH and remove dissolved metals from acidic mine drainage Type Journal Article
Year 1999 Publication Appl. Geochem. Abbreviated Journal
Volume 14 Issue 5 Pages 581-606
Keywords manganese oxide redox processes sulfate waters iron-oxides adsorption ions oxidation surfaces environments aluminum
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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ISSN 0883-2927 ISBN Medium
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Notes 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 Approved no
Call Number CBU @ c.wolke @ 17470 Serial 22
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Author (up) Cravotta, C.A., III; Watzlaf, G.R.; Naftz, D.L.; Morrison, S.J.; Fuller, C.C.; Davis, J.A.
Title 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 Type Book Chapter
Year 2002 Publication Abbreviated Journal
Volume Issue Pages
Keywords acid mine drainage; alkaline earth metals; aquatic environment; aquifers; calcium; carbonate rocks; chemical properties; construction; construction materials; crushed stone; dissolved materials; drainage; effluents; ground water; limestone; magnesium; metals; pH; pollution; porous materials; precipitation; retention; saturation; sedimentary rocks; sulfate ion; suspended materials 22, Environmental geology
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Publisher Academic Press Place of Publication Amsterdam Editor
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ISSN ISBN 0125135637 Medium
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Notes 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; GeoRef; English; 2004-040518; References: 66; illus. incl. 4 tables Approved no
Call Number CBU @ c.wolke @ 5686 Serial 81
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