Please read the abstract in the front section of this document / Dissertation (MSc (Food Science))--University of Pretoria, 2005. / Food Science / unrestricted

In view of very high toxicity potential of some heavy metals to aquatic life, there is a need for critical evaluation of known methods and development of new methods for purifying water and waste-water containing heavy metals. In this study, batch tests were performed to evaluate the relative efficiencies of six British Columbia coals in removing heavy metals (copper, lead, mercury and zinc) from water. On the basis of batch test data obtained, the best two coals, Kaiser Coal-Stock Pile Refuse and Kaiser Coal-Special Plant Feed, were tested on a continuous flow laboratory scale. The emphasis was placed on metal concentrations of 2 mg/1 and less for copper, lead and zinc and 5 vg/1 for mercury. The effects of adsorbate concentration, flow rate through the column (contact time), and pH of the solution on the adsorptive capacity of coal were investigated. A solution containing 0.5 mg/1 of each of copper, lead and zinc was tested to investigate the ability of the coal to remove metals from a mixture of many metals. The adsorptive capacity of the best two coals was also compared with some commercially available adsorbents. On the basis of capacity and rate of adsorption, Kaiser Coal-Stock Pile Refuse was found to be the best of the six coals tested. For the specific testing conditions in this investigation, the better metal-removing efficiency of coal as compared with activated carbon and nitrohumic acid indicate that the coal may be a feasible alternate to purify effluents containing heavy metals / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

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Uranium mill tailings from the Ranger mine, located in the Alligator Rivers Region of the Northern Territory, Australia, were examined to assess the effects of weathering and diagenesis on their long-term geochemical stability. Run of mill uranium tailings are a complex heterogeneous mixture of lithogenic ( primary gangue minerals and weathering products ) and secondary ( components that form during milling ) minerals, residual process chemicals and biogenic ( products of biological activity ) phases. Following transfer to the tailings storage facility, post depositional reactions alter the mineralogical and hydrochemical characteristics of the tailings solids and pore waters in accordance with weathering and diagenetic processes. In this thesis, a detailed examination of tailings cores and pore waters, kinetic column test work and geochemical modelling was combined with results from earlier studies to examine the key processes governing the geochemical stability of the Ranger tailings. Conclusions drawn from the work clearly demonstrates that the solid state speciation and mobility of metals and radionuclides in the tailings pile are governed by the processes of oxidative dissolution of sulfide minerals, weathering of phyllosilicates and organic matter diagenesis. The processes are spatially dependent, evolve over time and are influenced by the following key factors : 1. Tailings water content or degree of saturation ; 2. The nature and content of organic matter in the tailings ; 3. Redox potential of the tailings solid - pore water interface ; and 4. The specific reactivity of precursor minerals ( primary / secondary ) from the milling process and pore water solutes. Combined, these processes lead to the formation of authigenic minerals, which control the solubility of pore water constituents. These mechanisms will also have a profound impact on the long-term geochemical stability of the tailings pile and, as such, will need to be taken into account in the design, management and closure of the final tailings repositories at the Ranger site. / Thesis (Ph.D.)--School of Earth and Environmental Sciences, 2004.

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Final Report, Investigations on the Subsurface Disposal of Waste Effluents at Inland Sites / Grant No. 14-01-0001-1805 / United States Department of the Interior, The Office of Saline Water / By L.G. Wilson, Hydrologist, The Water Resources Research Center, The University of Arizona / February 1971.

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Thesis (M. Phil.)--University of Hong Kong, 1997. / Includes bibliographical references (leaf [149]-152).