Radionuclide contamination, remediation

Roh Y, Lee SY, Elless MP, Cho KS. Electro-enhanced remediation of radionuclide-contaminated groundwater using zero-valent iron (A35, pg. 1043, 2000). J Environ Sci Health, Part A 2000 35 1995. 

Adriano, D. C., Albright, J., Whicker, F. W., and Iskandar, I. K. (1997). Remediation of metal- and radionuclide-contaminated soil. In Remediation of Metal-Contaminated Soils, ed. Iskandar, I. K., and Adriano, D. C., Science Reviews, Northwood, Middlesex, England, 27-45. 

Phytoextraction has the potential to remediate many metal and radionuclide contaminated sites using a less invasive form of treatment than traditional methods such as escavation and disposal. There are four factors that influence or determine the ability of phytoextraction to effectively remediate a metal contaminated site 1). Site arability and plant biomass yields 2) metal solubility and availability for uptake 3) the ability of the plant to accumulate metals in the harvestable plant tissues and 4) regulatory criteria. 

The United States Department of Energy (DOE) manages approximately 1.9 billion cubic meters of radionuclide contaminated environmental media and 4.1 million cubic meters of stored, contaminated waste at 150 different sites located in 30 different states (i, 2). This environmental legacy is a result of the massive industrial complex responsible for defense related and non-defense related research, development and testing of nuclear weapons, nuclear propulsion systems and commercial nuclear power systems. Cleaning up the environmental legacy is expected to cost several hundred billion dollars over the next 5 to 7 decades. To reduce costs and speed remediation efforts the DOE has invested in waste treatment and environmental remediation research. 

Korolev VA, Barkhatova YE, Shevtsova EV. (2007). Elektrokinetic remediation of the radionuclide-contaminated soils. Proceedings of the 6th Symposium on Electrokinetic Remediation (EREM-2007), June 12-15, 2007, Vigo, Spain University of Vigo, pp. 

Knox, A. S. Seaman, J. C. Mench, M. J. Vangronsveld, J. Remediation of Metal- and Radionuclides-Contaminated Soils by In Situ Stabilization Techniques. In Environmental Restoration of Metals-Contaminated Soils Iskander, I. K., Ed. Lewis Publishers Baca Raton, FL, 2001. 

The demands for assessing the potential impact of radionuclides produced by military and nuclear power supply applications on environmental quality and human and the desire to remediate radionuclide-contaminated site have triggered an intensive and wide range of research activities. Soil chemical reactions are critical to both environment and human health and to successful remediation. This chapter s aim is to briefly describes the physical and chemical characteristics of the most important radioactive nuclides likely to be found in soils. The primary sources of these radionuclides include the fallout from atmospheric weapon tests, release from fuel processes facilities, nuclear material storage facilities, biomedical applications, and, of course, naturally-occurring radioactive elements. The forms and interactions of the radionuclides in soil environment are subsequently discussed. 

Srinath T, Verma T, Ramteke PW, Garg SK (2002) Chromium biosorption and bioaccumulation by chromate resistant bacteria. Chemosphere 48 427-435 Stephen JR, Macnaughton SJ (1999) Developments in terrestrial bacterial remediation of metals. Curr Opinion Biotechnol 10 230-233 Tabak HH, Lens P, van Hullebusch ED, Dejonghe W (2005) Developments in bioremediation of soils and sediments polluted with metals and radionuclides 1. Microbial processes and mechanisms affecting bioremediation of metal contamination and influencing metal toxicity and transport. Rev Environ Sci Bio/Technol. 4 115-156... 

Pollution of soils and waters by human activities is an important and widespread problem. This pollution by, organic and inorganic substances can affect individual organisms, human populations, and ecosystems, each in its own unique way. In particular former military installations, often used for weapons production and nuclear power plants represent a ongoing and substantial threat to environment and human health because of the specific pollutants that can be released Solvents, explosives, fuels, radionuclides, heavy metals, and metalloids all have been identified in the environment around these installations. Remediation technologies for these contaminated sites have been developed based on conventional systems utilising physical and chemical treatments, such as excavation and incineration, pump-and-treat methods, ultraviolet oxidation, soil washing, etc. 

Table 3.2 Characteristics of major radionuclides that occur in soil. Reprinted from Zhu, YG, Shaw G (2000) Soil contamination with radionuclides and potential remediation. Chemosphere 41 121-128. Copyright 2002 with permission of Elsevier...

Zhu, YG, Shaw G (2000) Soil contamination with radionuclides and potential remediation. 

In June of 1999, Edenspace Systems Corporation acquired Phytotech, Inc., a company specializing in phytoremediation technologies. Phytotech has developed several proprietary techniques for the phytoremediation of sites contaminated with heavy metals and radionuclides. Phytoremediation is an emerging bioremediation technology that uses plants to remediate contaminated media. Hyperaccumulation is a specific type of phytoremediation that can be used at sites contaminated by radionuclides and heavy metals. Hyperaccumulation may be defined as the ability... 

The TRUclean soil washing system is a patented, ex situ modular process that uses soil washing, size fractionation, and gravimetric separation techniques to remediate soils contaminated with radionuclides and heavy metals. The technology developer, Lockheed Martin Corporation, claims... 

In situ redox manipulation (ISRM) is an in situ, groundwater remediation technology for manipulating the oxidation-reduction (redox) potential of an unconfined aquifer to immobilize inorganic contaminants (metals, inorganic ions, and radionuclides) and to destroy organic contaminants (primarily chlorinated hydrocarbons). 

According to the vendor, the technology can be used to (1) remediate water and sludges contaminated with radionuclides and heavy metals, (2) restore gronndwater from mining operations, (3) treat naturally occurring radioactive materials (NORMs) in water or scale from petroleum operations, and (4) remediate man-made radionuclides stored in tanks, pits, barrels, or other containers. 

Apatite, a natural calcium fluoride phosphate, can adsorb low to moderate levels of dissolved metals from soils, groundwater, and waste streams. Metals naturally chemically bind to the apatite, forming extremely stable phosphate phases of metal-substituted apatite minerals. This natural process is used by UFA Ventures, Inc., and is called phosphate-induced metals stabilization (PIMS). The PIMS material can by used in a packed bed, mixed with the contaminated media, or used as a permeable barrier. The material may be left in place, disposed of, or reused. It requires no further treatment or stabilization. Research is currently being conducted on using apatite to remediate soil and groundwater contaminated with heavy metals, and the technology may also be applicable to radionuclides. The technology is not yet commercially available. 

Conca, J., Strietelmeier, Lu, N., Ware, S. D., Taylor, T. P., Kaszuba, J. Wright, J. 2002. Treatability study of reactive materials to remediate groundwater contaminated with radionuclides, metals, and nitrates in a four-component permeable reactive barrier. In Handbook of Groundwater Remediation Using Permeable Reactive Barriers. Elsevier Science, New York, 221-252. 

Classification system applies to any waste that contains radionuclides or hazardous chemicals. Waste classification system does not provide a substitute for site-specific risk assessments in developing waste acceptance criteria at particular disposal facilities or in developing criteria for remediation of particular contaminated sites. 

The radiation paradigm also is applied to other situations including cleanup of sites contaminated with uranium or thorium mill tailings, mitigation of indoor radon, remediation of elevated levels of naturally occurring radionuclides other than radon, and responses to radiation accidents. In these applications, the maximum acceptable risk has a value in the range of about 10 1 to 10 3 (Kocher, 1999). 

Electrokinetics is an in situ remediation technology applicable to soil or soil-like material with low hydraulic conductivities (e.g., clay) contaminated with heavy metals, radionuclides, and selected organic pollutants. The technique has been used in the past in the oil recovery industry and to remove water from soils. 

Phytoextraction is the best approach to remove the contamination primarily from soil and isolate it, without substantially alternating the soil structure and fertility. It is also referred as phytoaccumulation. As the plant absorbs, concentrates, and accumulates toxic metals and radionuclides from contaminated soils and waters into plant tissues, it is best suited for the remediation of diffusely polluted areas, where pollutants occur only at relatively low concentrations and superficial distribution in soil (Rulkens et al., 1998). Several approaches have been studied to enhance the effectiveness of phytoextraction, including the use of chelators to increase the bioavailability and plant uptake of metal contaminants. In order to make this... 

Naftz D. L., Fuller C. C., Davis J. A., Morrison S. J., Feltcorn E. M., Freethey G. W., Rowland R. C., Wilkowske C., and Piana M. (2002) Field demonstration of three permeable reactive barriers to control uranium contamination in groundwater. Fry Canyon, Utah. In Handbook of Groundwater Remediation Using Permeable Reactive Barriers—Applications to Radionuclides, Trace Metals, and Nutrients (eds. D. L. Naftz, S. J. Morrison, J. A. Davis, and C. C. Fuller). Academic Press, San Diego, CA, pp. 401-434. 

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