Characterization and remediation of soils contaminated with uranium (original) (raw)

Uranium Fixation and Removal from Different Soil Types: Review

Environmental contamination caused by radionuclides, in particular by uranium and its decay products is a serious problem worldwide. The development of nuclear science and technology has led to increasing nuclear waste containing uranium being released and disposed in the environment. The objective of this paper is to develop a better understanding of factors affecting uranium fixation and removal from different soils with different soil characteristics. Soils contaminated with uranium at concentrations above regulatory limits pose an environmental and human health risk. Investigations about uranium content and fate in soils revealed several finding depending on soil factors, radionuclide source and nature, and existing vegetation in the area. In organic rich soils U seems to be more soluble and bioavailable. Data demonstrates the effectiveness of soil amendments (Hydroxyapatite, illite and zeolite) in reducing the mobility of U, which makes in-place immobilization an effective remediation alternative. In contrast to increase U solubility and leach-ability the maximum solubilization of U was observed with a combined soil acidification and citric acid addition, which may be necessary to maximize the phyto-extraction of U from soils with a pH >6.0. Keywords: Remediation; U-speciation; U-chemistry in soils

REMEDIATION AND BIOREMEDIATION OF URANIUM CONTAMINATED SOILS

This paper reviews the recent advances in uranium removal from contaminated soils, using either Chemical and/or biological techniques (such as hyperaccumulator plants, or high biomass crop species after soil treatment with chelating compounds)..

Uranium Fixation and Removal from Different Soil Types (final).pdf

Environmental contamination caused by radionuclides, in particular by uranium and its decay products is a serious problem worldwide. The development of nuclear science and technology has led to increasing nuclear waste containing uranium being released and disposed in the environment. The objective of this paper is to develop a better understanding of factors affecting uranium fixation and removal from different soils with different soil characteristics.

Uranium soils decontamination by washing method

UPB Scientific Bulletin, Series B: Chemistry and Materials Science

A remediation method is presented in order to limit the pollution degree due to mining activities of soils with radioactive uranium. The washing method of polluted soils was investigated.For remediation of radioactive soils the following systems were used : a) water, b) 0.1M sulfuric acid, and c) sodium chloride solution (100 g/L sodium chloride + 10 g /L sodium carbonate). The washing conditions in a system with mechanical agitation werw: mass ratio solid/liquid 1:2, contact time 2 hours, temperature 20 ± 2ºC.Experimental investigations were performed on four types of soils, which have been characterized in terms of particle size distribution, texture and chemical composition.It was established the remediation degree for each type of soil and reagent.

Decontamination of radioactive contaminated soils:currenet prespective

M.S. Khan et al. (eds.), Biomanagement of Metal-Contaminated Soils, Environmental Pollution 20, DOl 10.1007/978-94-007-1914-9_17, © Springer Science+Business Media B.V. 2011, 2011

Radio-nuclides exist in the environment naturally and, in more recent times, have been added by nuclear power and weapons. The carcinogenic nature and long half-lives of many radionuclides make them a potential threat to human health. Moreover, there is an increasing trend of uranium accumulating in soils due to a number of deliberate or wrong practices. Also, the contamination of land by naturally occurring radionuclides from "non-nuclear" industries include uranium mining and milling, metal or coal mining, radium and thorium factories, and the processing of materials containing technologically enhanced levels of natural radioactivity. As a consequence, there would be a risk for ecosystems, gro-systems, and health. It is suggested that knowledge of the mechanisms that control the behavior of such heavy metals must be improved and be used for risk assessment and proposition of remediation treatments. Phytoremediation has been used to extract radionuclides and other pollutants from contaminated sites. The accuracy and success of these applications depend on an understanding of the processes involved in plant uptake of radionuclides. The recent advances in uranium removal from contaminated soils, using either chemical and/or biological techniques (such as hyperaccumulator plants, or high biomass crop species after soil treatment with chelating compounds) are reviewed and discussed.

Removal of depleted uranium from contaminated soils

Journal of Hazardous Materials, 2006

Contamination of soil and water with depleted uranium (DU) has increased public health concerns due to the chemical toxicity of DU at elevated dosages. For this reason, there is great interest in developing methods for DU removal from contaminated sources. Two DU laden soils, taken from U.S. Army sites, were characterized for particle size distribution, total uranium concentration and removable uranium. Soil A was found to be a well graded sand containing a total of 3210 mg/kg DU (3.99 × 10 4 Bq/kg, where a Becquerel (Bq) is a unit of radiation). About 83% of the DU in the fines fraction (particle diameter <0.075 mm, total DU 7732 mg/kg (9.61 × 10 4 Bq/kg)) was associated with the carbonate, iron and manganese oxide and organic matter fractions of the material. Soil B was classified as a sandy silt with total DU of 1560 mg/kg (1.94 × 10 4 Bq/kg). The DU content in the fines fraction was 5171 mg/kg (6.43 × 10 4 Bq/kg). Sequential extraction of the Soil B fines fraction indicated that 64% of the DU was present either as soluble U(VI) minerals or as insoluble U(IV). Citric acid, sodium bicarbonate and hydrogen peroxide were used in batch experiments to extract DU from the fines fraction of both soils. Citric acid and sodium bicarbonate were relatively successful for Soil A (50-60% DU removal), but not for Soil B (20-35% DU removal). Hydrogen peroxide was found to significantly increase DU extraction from both soils, attaining removals up to 60-80%.

Public Health, Acts and Methods of Remediation of Uranium from Ground Water

Uranium is natural radionuclides present at mBq/lto Bq/l concentrations in many aquifers worldwidedue to leaching and transport mechanism from natural deposits. Human activities such as mill tailings, nuclear industry, coalcombustion and the use of phosphate fertilizers can also alter the natural composition of groundwater. Uranium through water transferred to the human food chain and its ingestion and inhalation causes many health problems. Manybioindicators are used to predict the path and durationof uranium remain in the body, which permits the risks calculation to specific tissues, organs as well as the whole body. So, a combination of both biological and non-biological methods seems to be the most promising way to efficiently remediate the uranium from groundwater.Hydrogeologists increasinglyrely on bioremediation of contaminated groundwaterbased on immobilization of the metal by bioreduction or biosorption. This review deals with the trafficking, prevention and possible remediation of uranium from groundwater.