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LaPointe, F., Fytas, K., & McConchie, D. (2005). Using permeable reactive barriers for the treatment of acid rock drainage. International journal of surface mining, reclamation and environment, 19(1), 57–65.
Abstract: Acid mine drainage (AMD) is the most serious environmental problem facing the Canadian mineral industry today. It results from oxidation of sulphide minerals (e.g. pyrite or pyrrhotite) contained in mine waste or mine tailings and is characterized by acid effluents rich in heavy metals that are released into the environment. A new acid remediation technology is presented, by which metallurgical residues from the aluminium extraction industry are used to construct permeable reactive barriers (PRBs) to treat acid mine effluents. This technology is very promising for treating acid mine effluents in order to decrease their harmful environmental effects
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(1998). 'Green' company offers desalination technology. Water Sewage and Effluent, 18(4), 9–11.
Abstract: Water and wastewater treatment activities, projects and capabilities of South African environmental engineering specialist Envig are detailed. The company, as part of the Weir Wesgarth Consortium, has pre-qualified for the major Namibian Water Supply Project, one of the largest of its kind to date in southern Africa. This project involves the desalination of seawater to meet increasing water demand and shortfalls. Envig, if awarded the contract, would be involved in construction of three or four reverse osmosis or mechanical vapour compression sea water desalination plants and associated infrastructure. The company is also involved in a mine water desalination project at the Eskom Tutuka Power Station. A reverse osmosis plant using low fouling maintenance is being installed to deal with acid mine drainage water. Details of the design and operation of this plant are given.
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Benner, S. G., Blowes, D. W., & Ptacek, C. J. (1997). A full-scale porous reactive wall for prevention of acid mine drainage. Ground Water Monitoring and Remediation, 17(4), 99–107.
Abstract: The generation and release of acidic drainage containing high concentrations of dissolved metals from decommissioned mine wastes is an environmental problem of international scale. A potential solution to many acid drainage problem is the installation of permeable reactive walls into aquifers affected by drainage water derived from mine waste materials. A permeable reactive wall installed into an aquifer impacted by low-quality mine drainage waters was installed in August 1995 at the Nickel Rim mine site near Sudbury, Ontario. The reactive mixture, containing organic matter, was designed to promote bacterially mediated sulfate reduction and subsequent metal sulfide precipitation. The reactive wall is installed to an average depth of 12 feet (3.6 m) and is 49 feet (15 m) long perpendicular to ground water flow. The wall thickness (flow path length) is 13 feet (4 m). Initial results, collected nine months after installation, indicate that sulfate reduction and metal sulfide precipitation is occurring. Comparing water entering the wall to treated water existing the wall, sulfate concentrations decrease from 2400 to 4600 mg/L to 200 to 3600 mg/L; Fe concentration decrease from 250 to 1300 mg/L to 1.0 to 40 mg/L, pH increases from 5.8 to 7.0; and alkalinity (as CaCO<inf>3</inf>) increases from 0 to 50 mg/L to 600 to 2000 mg/L. The reactive wall has effectively removed the capacity of the ground water to generate acidity on discharge to the surface. Calculations based on comparison to previously run laboratory column experiments indicate that the reactive wall has potential to remain effective for at least 15 years.
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Coulton, R., Bullen, C., & Hallett, C. (2003). The design and optimisation of active mine water treatment plants. Land Contam. Reclam., 11(2), 273–280.
Abstract: This paper provides a 'state of the art' overview of active mine water treatment. The paper discusses the process and reagent selection options commonly available to the designer of an active mine water treatment plant. Comparisons are made between each of these options, based on technical and financial criteria. The various different treatment technologies available are reviewed and comparisons made between conventional precipitation (using hydroxides, sulphides and carbonates), high density sludge processes and super-saturation precipitation. The selection of reagents (quick lime, slaked lime, sodium hydroxide, sodium carbonate, magnesium hydroxide, and proprietary chemicals) is considered and a comparison made on the basis of reagent cost, ease of use, final effluent quality and sludge settling criteria. The choice of oxidising agent (air, pure oxygen, peroxide, etc.) for conversion of ferrous to ferric iron is also considered. Whole life costs comparisons (capital, operational and decommissioning) are made between conventional hydroxide precipitation and the high density sludge process, based on the actual treatment requirements for four different mine waters.
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Laine, D. M., & Jarvis, A. P. (2003). Engineering design aspects of passive in situ remediation of mining effluents. Land Contam. Reclam., 11(2), 113–126.
Abstract: Passive treatment of contaminated effluents can offer a 'low cost' management opportunity to remediate drainages to the standards required by enforcement agencies. However, the initial cost of construction of passive treatment systems is significant and often in excess of that for active treatment systems. It is therefore important that the engineering design of the passive systems produces an effective and efficient scheme to enable the construction and maintenance costs to be minimised as far as possible. Possible parameters for the design of passive systems are suggested to seek to obtain uniformity in size and layout of treatment elements where this may be possible. Passive treatment systems include aeration systems, sedimentation ponds, aerobic and anaerobic wetlands, anoxic limestone drains and reducing alkalinity producing systems. Most active treatment systems also include passive elements in the treatment stream. The basic design considerations that should be considered to ensure the construction of efficient systems are discussed.
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