**6.1 Plant species**

*Assessment and Management of Radioactive and Electronic Wastes*

destruction etc.

heating, etc.

Over the previous years, several methods have been used to deal with the radioactive waste from contaminated sites. Though, these methods are costly and inefficient in their concert. The chemical methods generate large volumes of sludge and increase the cost of maintenance. Thermal methods are technically difficult and adversely affect the valuable component of soil by degrading it [21]. Two major procedures that are conventionally used to remediate the radioactive contaminated sites are: [22].

1.*Ex-situ methods***:** This method requires the removal of contaminated soil for treatment on/off site and then returning the treated soil to the site. The example of ex-situ methods are; soil leaching, solidification, immobilization, vitrification, heap leaching, ground disposal, sea disposal, incineration, and or

2.*In-situ methods***:** In this method excavation of contaminated location is not needed. The examples are; de-chlorination, bottom sealing, electromagnetic

Phytoremediation is a novel resolution that effectively and inexpensively extracts out the contaminants from the site and scrubs up the wasteland [23]. Phytoremediation makes use of green plants to clean up and treat radioactive contaminated sites for example soil, water and sediments. Plants have notable features that help them absorb contaminants into their systems with their endorsement capabilities such as translocation, bioaccumulation and contaminant degradation. Many plant species have been successful in efficiently accumulating the radionuclides in their stems and leaves and hence remediating the contaminated site [21]. This chapter evaluates some of the research that has been done on phytoremediation of radioactive metals and aims to discuss the potential of phytoremediation, highlight the general mechanisms of plant uptake, give a brief overview on radioactive metals (especially: Uranium-238, Thorium-232, Radium-226) uptake by plants,

and report the advantages and limitations associated with this method.

organs of the plant—leaves, stems and roots [24, 25].

1.**Phytoextraction:** Plants degrading pollutants from the soil (tailings) and

2.**Phytodegradation:** Plants removing pollutants by using hydrolytic enzymes and metabolites in plants; however, this method may be limited only to degra-

3.**Phytostabilization:** Plants reducing mobility and bioavailability of pollutants in the soil either by immobilization and precipitation, or by preventing

4.**Phytovolatilization:** Volatilization of pollutants into the air directly or indirectly via plant uptake into tissues and organs, and then transformation of the

5.**Rhizofiltration:** Plant roots strongly absorbing, accumulating and/or precipitating contaminants from aqueous waste streams or soil water almost exclu-

concentrating the contaminants in the harvestable portions of plants; i.e., in all

**5. Six main subgroups in phytoremediation**

dation of organic contaminants [26, 27].

products into volatile compounds [25, 30].

contaminant migration [28, 29].

sively into the root system [31, 32].

**34**

Plant species with superior remediation ability of the concerned radioactive waste are screened and carefully chosen. The success of phytoremediation technique depends upon the ability of the plant to accumulate [36].
