Phytoremediation of Radionuclides

 

Rhizofiltration of Contaminated Waters

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Rhizofiltration

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References
“… rhizofiltration is the removal by plant roots of contaminants in surface water, waste water, or ground water extracted to the surface, through adsorption, precipitation, or absorption by the roots of a plant.” (Tome et al. 2008)
http://www.aspb.org/publicaffairs/briefing/phytoremediation.cfm
Rhizofiltration has been shown to be highly effective in the removal of uranium and radium from contaminated waters both in the laboratory and field (Dushenkov et al. 1997, Tome et al. 2008). Ex-situ rhizofiltration systems are essentially a closed hydroponic system where contaminated waters are circulated through the rooting medium of plants. In-situ systems usually are in the form of a created wetland with specific pollutants pumped into the 'wetland' and all effluent monitored and probably captured. The most appropriate plant for a rhizofiltration system is one capable of rapid growth, high root biomass, and has the ability to remove radionuclides and heavy metals from the water in relatively high concentrations (Tome et al. 2008). Annual sunflower (Helianthus annuus) has been used by Dushenkov et al. (1997) and Tome et al. (2008) for uptake studies of uranium and radium and additionally research should screen ecotypes or varieties of the species and consider transgenic modification.Water hyacinth (Eichhornia ssp.) has also been used for rhizofiltration. Both the sunflower and water hyacinth rapidly removed large concentrations of the radionuclides from the water, often in less than 24 hours. The majority of radionuclides accumulate in the roots of the plants (50-70%) or as precipitates on the roots (Dushenkov et al. 1997, Tome et al. 2008). Following rhizofiltration of the radioactive waters, the plant biomass and waters must be treated and disposed of properly. The ‘Disposal’ section of this website briefly covers waste minimization and disposal of treatment by-products.