Abstract: In this paper experience obtained with THIOPAQ technology treating Acid Mine Drainage is described. THIOPAQ Technology involves biological sulfate reduction technology and the removal of heavy metals as metal sulfide precipitates. The technology was developed by the PAQUES company, who have realised over 350 high rate biological treatment plants world wide. 5 plants specially designed for sulfate reduction are successfully operated on a continuous base (1998 status). At Budelco, a zinc refinery in the Netherlands, an acid groundwater stream is effectively treated since 1992, removing metals and sulfate. At Kennecott Utah Copper (USA) a demo plant is in operation since 1995. An acid groundwater flow is treated to remove sulfate and metals, whereas the excess sulfide is used to selectively recover copper economically. Early 1998, a demonstration project was executed at the Wheal Jane mine in Cornwall, UK. In this demonstration project it has been proven that THIOPAQ technology can effectively be used to treat the Wheal Jane Acid Mine Drainage. Relative to lime dosing technology, very high removal efficiencies of all heavy metals (including cadmium and arsenic) can be obtained.

Abstract: Rodiek, J., Verma, T.R. and Thames, J.L., 1976. Disturbed land rehabilitation in Lynx Creek Watershed. Landscape Plann., 2: 265-282. The Lynx Creek Watershed is located on the Prescott National Forest about 8 km south of Prescott, Arizona. The watershed, with an area of 7304 ha, has experienced intensive copper and gold mining activities in the past. Approximately 13% of the area still consists of patented mining claims (mainly copper). There are numerous abandoned mine shafts, waste dumps and mine tailings in the area. Past mining activities in the watershed have caused significant deterioration in water quality within and downstream from the mining sites. Mine drainage includes water flowing from mine shafts, surface runoff and seepage from mining dumps. Drainage from the numerous old mining sites contributes to the toxic mineral and sediment pollution of the water resources in the area. The pollutants in the form of dissolved, suspended or other solid mineral wastes and debris, enter in the streams of ground water. Aquatic life and recreation potential of the watershed is greatly reduced by the water pollution problem from the abandoned mines. The pollutants from the abandoned mines enter into Lynx Lake which is located 10 km southeast of Prescott. Lynx Lake, a trout fisheries lake, was created by a dam built in 1963 by the Arizona Game and Fish Department. The lake is 22 surface hectares in size with the storage capacity of 1.85 x 106 m3. The average yearly flow of sediment into the lake is 2900 m3. The sediment is slightly acidic and has a high concentration of copper, manganese, iron, zinc, and sulfates. The Sheldon dump and tailings pond are considered two major sources of pollution. Increasing need to direct additional attention toward mineral related problems made it necessary to coordinate U.S. Forest Service efforts with others involved in mining and reclamation. The Forest Service started SEAM (Surface Environment And Mining) in 1972 to coordinate interagency reclamation efforts. The Sheldon Mine dump and tailings pond were undertaken as a reclamation project through the coordinated efforts of the Forest Service, and the School of Renewable Natural Resources, University of Arizona at Tucson. The project is aimed at reclaiming some of the abandoned spoils in the Lynx Creek watershed and monitoring of water quality in the creek to evaluate the effectiveness of reclamation procedures. The reclamation approach includes recontouring, revegetating, drainage control and visual impact modification activities. The results to date have been encouraging. There was an excellent vegetation cover established within 5 weeks of seeding. Runoff and sediment control on the regraded slopes seemed quite effective. The methodology and technological experience gained from the reclamation project will provide invaluable information for reclaiming any abandoned mining sites within the Ponderosa Pine Ecosystem.

Abstract: Acid mine drainage (AMD) is one of the most significant environmental challenges facing the mining industry worldwide. Water infiltrating through the metal sulphide minerals, effluents of mineral processing plants and seepage from tailing dams becomes acidic and this acidic nature of the solution allows the metals to be transported in their most soluble form. The conventional treatment technologies used in the treatment of acid mine drainage are expensive both in terms of operating and capital costs. One of the methods of achieving compliance using passive treatment systems at low cost, producing treated water pollution free, and fostering a community responsibility for acid mine water treatment involves the use of wetland treatment system. These wetlands absorb and bind heavy metals and make them slowly concentrated in the sedimentary deposits to become part of the geological cycle. In this paper a critical review of the heavy metal removal mechanism involving various physical, chemical and biological processes, which govern wetland performance, have been made. This information is important for the siting and use of wetlands for remediation of heavy metals.