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Goulet, R. R. (2001). Changes in dissolved and total Fe and Mn in a young constructed wetland: Implications for retention performance. Ecological Engineering, 17(4), 373–384.
Abstract: Surface-flow wetlands are generally considered sinks for Fe and Mn but they may also export and affect the partitioning of these metals. This study was undertaken to evaluate the effect of a young constructed wetland on the retention and transformation of both dissolved and particulate Fe and Mn. Duplicate water samples were collected every three days at the inlet and outlet structures of the Monahan Wetland, Kanata, Ontario, from spring of 1997 to 1999. While on a yearly basis the wetland showed significant retention of che dissolved phase, the retention of total Fe and Mn was poor. There were strong seasonal differences in retention and, during the winter, the wetland was a source. The wetland transformed dissolved into particulate Fe and Mn from spring to fall whereas during the winter, dissolved Fe and Mn were released. Changes in pH, alkalinity and temperature could explain 11% and 40% of the outlet variation in the ratio of dissolved to total Fe and Mn respectively. Furthermore, from spring to late summer, planktonic algal biomass was negatively related to the ratio of dissolved to total Fe and Mn implying a role in Fe and Mn transformations in young wetlands where emergent and submerged vegetation have yet to dominate the system. (C) 2001 Elsevier Science B.V. All rights reserved.
Keywords: mine water treatment
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Chung, I. J. (2001). Immobilization of arsenic in tailing by using iron and hydrogen peroxide. Environ. Technol., 22(7), 831–835.
Abstract: Under environmental conditions, arsenic (As) reveals anionic behavior and is converted into various forms in accordance with the Eh/pH condition. This causes the difficulty of treating As with other heavy metals in tailing. This study was carried out to develop the immobilization method of arsenic in tailing as ferric arsenate (FeAsO4) using hydrogen peroxide. According to experimental results, the extracted concentrations of arsenic and iron (Fe) from tailing were reduced up to 84% and 93%, respectively. In the experiment using pure Pyrite (FeS2) and As solution, As concentration decreased with an increase of hydrogen peroxide dosage. The experimental results of re-extraction showed that only 10% of As and 20% of Fe were extracted in the case of using hydrogen peroxide. As a result, the long-term stability of this method was clarified.
Keywords: mine water treatment
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Dempsey, B. A., & Jeon, B. - H. (2001). Characteristics of sludge produced from passive treatment of mine drainage. Geochem.-Explor. Environ. Anal., 1(1), 89–94.
Abstract: In the 1994 paper by Brown, Skousen & Renton it was argued that settleability and wet-packing density were the most important physical characteristics of sludge from treatment of mine drainage. These characteristics plus zeta-potential, intrinsic viscosity, specific resistance to filtration, and coefficient of compressibility were determined for several sludge samples from passive treatment sites and for several sludge samples that were prepared in the laboratory. Sludge from passive systems had high packing density, low intrinsic viscosity, low specific resistance to filtration and low coefficient of compressibility compared to sludge that was produced after addition of NaOH.
Keywords: acid mine drainage; aerobic environment; anaerobic environment; Appalachian Plateau; Appalachians; carbonate rocks; coagulation; compressibility; decontamination; density; drainage; filtration; geochemistry; Howe Bridge; Jefferson County Pennsylvania; limestone; mining geology; North America; passive systems; Pennsylvania; pH; pollution; ponds; rates; reclamation; sedimentary rocks; settling; sludge; slurries; suspended materials; United States; viscosity; wet packing density; wetlands; zeta-potential 22, Environmental geology
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Demchak, J., Morrow, T., Skousen, J., Donovan, J. J., & Rose, A. W. (2001). Treatment of acid mine drainage by four vertical flow wetlands in Pennsylvania Evolution and remediation of acid-sulfate groundwater systems at reclaimed mine-sites. Geochemistry – Exploration, Environment, Analysis, 1(1), 71–80.
Abstract: Acid mine drainage (AMD) is a serious problem in many watersheds where coal is mined. Passive treatments, such as wetlands and anoxic limestone drains (ALDs), have been developed, but these technologies show varying treatment efficiencies. A new passive treatment technique is a vertical flow wetland or successive alkalinity producing system (SAPS). Four SAPS in Pennsylvania were studied to determine changes in water chemistry from inflow to outflow. The Howe Bridge SAPS removed about 130 mg l (super -1) (40%) of the inflow acidity concentration and about 100 mg l (super -1) (60%) iron (Fe). The Filson 1 SAPS removed 68 mg l (super -1) (26%) acidity, 20 mg l (super -1) (83%) Fe and 6 mg l (super -1) (35%) aluminium (Al). The Sommerville SAPS removed 112 mg l (super -1) (31%) acidity, exported Fe, and removed 13 mg l (super -1) (30%) Al. The McKinley SAPS removed 54 mg l (super -1) (91%) acidity and 5 mg l (super -1) (90%) Fe. Acid removal rates at our four sites were 17 (HB), 52 (Filson1), 18 (Sommerville) and 11 (McKinley) g of acid per m (super 2) of surface wetland area per day (g/m (super 2) d (super -1) ). Calcium (Ca) concentrations in the SAPS effluents were increased between 8 and 57 mg l (super -1) at these sites. Equilibrators, which were inserted into compost layers to evaluate redox conditions at our sites, showed that reducing conditions were generally found at 60 cm compost depths and oxidized conditions were found at 30 cm compost depths. Deeply oxidized zones substantiated observations that channel flow was occurring through some parts of the compost. The Howe Bridge site has not declined in treatment efficiency over a six year treatment life. The SAPS construction costs were equal to about seven years of NaOH chemical treatment costs and 30 years of lime treatment costs. So, if the SAPS treatment longevity is seven years or greater and comparable effluent water quality was achieved, the SAPS construction was cost effective compared to NaOH chemical treatment. Construction recommendations for SAPS include a minimum of 50 cm of compost thickness, periodic replacement or addition of fresh compost material, and increasing the number of drainage pipes underlying the limestone.
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Banks, S. B., & Banks, D. (2001). Abandoned mines drainage; impact assessment and mitigation of discharges from coal mines in the UK. In R. N. Yong, & H. R. Thomas (Eds.), Geoenvironmental engineering Engineering Geology (pp. 31–37). 60.
Abstract: The UK has a legacy of pollution caused by discharges from abandoned coal mines, with the potential for further pollution by new discharges as groundwaters continue to rebound to their natural levels. In 1995, the Coal Authority initiated a scoping study of 30 gravity discharges from abandoned coal mines in England and Scotland. Mining information, geological information and water quality data were collated and interpreted in order to allow a preliminary assessment of the source and nature of each of the discharges. An assessment of the potential for remediation was made on the basis of the feasibility and relative costs of alternative remediation measures. Environmental impacts of the discharges and of the proposed remediation schemes were also assessed. The results, together with previous Coal Authority studies of discharges in Wales, were used by the Coal Authority, in collaboration with the former National Rivers Authority and the former Forth and Clyde River Purification Boards, to rank discharge sites in order of priority for remediation.
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