Reclamation of Heavy Metals

Gieger,G.,Federer,P. Sticher, H.(1993). Reclamation of heavy metal-contaminated soils field studies and germination experiments. Journal of Environmental Quality, 22,201—7. 

Major areas of application are in the field of aqueous electrochemistry. The most important application for perfluorinated ionomers is as a membrane separator in chloralkali cells.86 They are also used in reclamation of heavy metals from plant effluents and in regeneration of the streams in the plating and metals industry.85 The resins containing sulfonic acid groups have been used as powerful acid catalysts.87 Perfluorinated ionomers are widely used in worldwide development efforts in the held of fuel cells mainly for automotive applications as PEFC (polymer electrolyte fuel cells).88-93 The subject of fluorinated ionomers is discussed in much more detail in Reference 85. 

Williamson A., Johnson M.S. Reclamation of metalliferous mine wastes. In Effect of Heavy Metal Pollution on Plants. Vol. 2 Metals in Environment, N.W. Lepp, ed. London, UK Applied Science Publishers, 1981. 

Tmovsky, M. Oxer, J.P. Rudy, R.J. Hanchak, M.J. Hartsfield, B. Site Remediation of Heavy Metals Contaminated Soils and Groundwater at a Form Battery Reclamation Site in Florida, In Hazardous Waste, Detection, Control, Treatmeru Abbou, R., Ed. Elsevier Science Publishers, B.V. Amsterdam, The Netherlands, 1988 pp 1581-1590. 

Clijsters, H., and Vangronsveld, J. (1994). Reclamation of contaminated soils by in situ immobilisation of heavy metals. In Workshop, 1992, Institut National Agronomique, Paris, ed. Avril, C., and Impens, R., Cadmium Industry Enviromnent, Brussels, Belgium, 57-62. 

Metal hydroxide sludges are produced in the removal of metals such as lead, chromium, nickel, and zinc from wastewater by raising the pH to such a level that the corresponding hydroxides or hydrated metal oxides are precipitated. The disposal of these sludges is a substantial problem because of their toxic heavy metal content. Reclamation of the metals is an attractive alternative for these sludges. 

Because of its ability to remove minute particles such as fats, protein and pathogens [29,216], membrane filtration is another widely used technology of choice for superior water and large-scale reclamation of waste-water. The factors such as pressure, chemical composition, temperature, feed flow and interactions between components in the feed flow and the membrane surface influence the separation performance of membranes [116]. Conventional techniques have their own inherent limitations such as less efficiency, sensitive operating conditions, production of secondary sludge and further the disposal is a costly affair [4, 41, 199]. Another powerful technology is adsorption of heavy metals from industrial waste-water [77, 79]. 

Galiulin, R.F, Bashkin, V.N, Galiulina, R.R and Birch, P. (2001). A Critical Review Protection from Pollution by Heavy Metals — Phytoremediation of Industrial Wastewater. Land Contamination Reclamation, 9(4), 349-357... 

The MRU technology is not applicable to heavy-metal-contaminated soils nor to radioactive waste contamination. The one exception to heavy-metals remediation is mercury. The vaporization temperature for mercury is well within the operating range of the MRU, and because of closed chamber construction, it is ideally suited for the removal and reclamation of mercury from contaminated soil. 

Saunders FM. 1988. Heavy metal impact on disposal and reclamation of aluminum-anodizing residues. Environ Technol Lett 9 945-956. 

Sewage treatment and many on-site facilities produce biosolids (sewage sludge). These may be used as a soil conditioner in agriculture or for other purposes, such as land reclamation. Biosolids that are not used for these purposes are disposed of in various ways, including by landfill. In some circumstances, the disposal of biosolids may give rise to leaching, particularly of nitrates. Where biosolids are heavily contaminated with industrial waste, such as heavy metals, these contaminants may also need to be considered. 

Typical examples, which will be discussed in more detail below, are the zinc process, or the Coldstream process for reclamation of cemented carbide scrap, and the oxidation and subsequent reduction of tungsten heavy metal turnings or thoriated tungsten (see Table 11.3). 

Reclamation of treated wastewaters by land disposal has long been discouraged, mainly for sanitary reasons. This, in our opinion, reflects the concern that not enough is known about the transport and fate of potentially hazardous wastewater constituents (biorefractory organic molecules, heavy metals, and biological agents) in the surface and subsurface environments. 

General topics Indude site assessment, sample digestion, bioremediation, and mathematical models for heavy metal transport In soils. Examples of specific chapters indude lead at an abandoned battery reclamation site, effect of acidic intiuent on Ion transport in sandy soil, and chemical stabitization of sandblasting grit. 

Land reclamation. Lime stabilisation is being used in the reclamation of a wide range of derelict sites. Not only does the lime stabilise pozzolanic material on the site, but it helps to neutralise acidic residues, immobilise heavy metals and saponify oily wastes. It can also be used to dry out a site to enable piling equipment to be brought in, or to assist with the removal of sludges. 

Table 6.2 shows the total metal content in the surface soil layer, in relation to the distance from the smelter, and based on our own work and on other data. Relatively low Cu and Pb concentrations measured close to emission sources probably resulted from the deep ploughing undertaken as a first step of soil reclamation. In this way, the heavy metals previously accumulated in the surface layer were "diluted" in the top-soil. It is not definitely known whether such treatment would, or would not, cause any changes in metal mobility. 

For example, only about half the global production of lead (4 million tonnes) is recycled [434] so that about 2 million tonnes of the lead which is mined annually ends up dispersed to a varying extent, as an environmental contaminant. In addition, the process of reclamation of metals may itself lead to heavy contamination of the environment and defoliation and deaths in farm stock have been encountered in Scotland in the vicinity of operations associated with recovery of metals from spent cables. In this instance, the contamination was largely airborne, and available levels of trace metals in the soil in the vicinity of the operation had been enhanced to the following extent in relation to the levels characteristic of uncontaminated rural soils in the area cadmium -120-fold, copper - 30-fold, lead - 1,000-fold, nickel - 100-fold, zinc -4,000-fold. 

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