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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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Vegt, A. L. de, Bayer, H. G., & Buisman, C. J. (1998). Biological sulfate removal and metal recovery from mine waters. Min. Eng., 50(11), 67–70.
Abstract: Metalle und Sulfat können aus Grubenwässern in einem zweistufigen biologischen Prozeß entfernt werden. In der ersten Stufe wird das Sulfat durch Bakterien zu Schwefelwasserstoff reduziert. Dieser reagiert mit den gelösten Metallen zu unlöslichem Metallsulfid. Im zweiten Schritt wird überschüssiger Schwefelwasserstoff durch Bakterien zu elementarem Schwefel oxidiert. Eine nach diesem Verfahren arbeitende Anlage wurde 1992 durch die Budelco Zinc Refinery in den Niederlanden installiert. Diese verarbeitet täglich 5000 m(exp 3) Gundwasser. Zur Weiterentwicklung des Verfahrens für die Entfernung von Metallen und Sulfat aus Grundwasser und zur gezielten Kupfergewinnung aus Laugungswässern wurde 1995 in der Kupfergrube Bingham Canyon Utah, USA eine entsprechende Pilotanlage in Betrieb genommen. Anhand dieser Pilotanlage werden der Verfahrensablauf und erste Erfahrungen dargestellt sowie ein Überblick über das Untersuchungsprogramm gegeben.
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Morfitt, B., Brewer, W., & Frobel, R. (1998). Cleaning up the Summitville Mine Superfund Site. Geotechnical Fabrics Report, 16(5), 38–41.
Abstract: A multi-layered geosynthetic system that includes geosynthetic-clay liners (GCL) and a geonet-composite drain (GNGC) is being used to cap and stabilize a 178000 m(exp 2) heap-leach pad at the Summitville Mine Superfund Site in Colorado. Selected were materials on the basis of design requirements for permeability, strength, extreme site conditions and cost. The Summitville cleanup called for a heap-leach pad cap to provide a barrier that would prevent precipitation from infiltrating the pad material. This long-term remediation prevents the pile from becoming saturated and allowing water to overflow the downslope dike, which could cause instability to dike and pond. Three geosynthetic alternatives were proposed. The contractor, that was awarded the heap leach pad, phase 2 contract, decided for a geosynthetic clay liner cap placed directly on the redesigned slopes. Bentofix NW-8 was used as GCL and TexNet TN was selected as the geocomposite drain. Conformance testing, subgrade preparation review, geosynthetic installation/repair inspection and review of cover material placement, performed by independent construction-quality assurance, showed that GCL is a well-suited cap material for heap leach pads, where high wind, cold temperatures rain and high altitude hinder construction. The robust geosynthetic allowed on-site coarse material to be used in the subgrade and cover layer, which saved the cost of importing more expensive bedding material.
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