**Abstract**

Phytoremediation technology incorporates living plants for in situ remediation of contaminated soils, sediments, tailings and groundwater. These practices integrates the removal, or degradation of toxic wastes that is capable of cleaning up an area with low to moderate levels of contamination. Phytoremediation has been studied widely for metals, pesticides, solvents, explosives, crude oil, etc. These studies and research are advanced, especially in small-scale operations. Phytoremediation has been successfully tested to decontamination of radioactive sites. The chapter initiates with possible remediation methods used for radioactive wastes where we will discuss types and nature of radioisotope contamination. Then we discuss discusses the classifications of phytoremediation techniques to treat radioactive contaminated waste. Phytoremediation performance depends on numerous factors such as soil composition, level of toxicity, suitable plant species, etc. Conversely, phytoremediation prospects low cost, practical and ecologically viable approach for low-level radiation waste clean-up.

**Keywords:** phytoremediation, plants, radioactive pollutants, radioisotope, low-level radiation waste

### **1. Introduction**

The term "Phytoremediation" derived from Greek and Latin words. The word "Phyto" from Greek "phutón" meaning plants, while the word "remediation" from Latin "remedium" meaning a remedy or cure or correct evil. Phytoremediation is a fairly new technology introduced in 1980s that use plants to clean/partly clean contaminated locations, or reduce the contaminants less harmful [1–4]. It is also named as green remediation, agro-remediation, botano-remediation, and vegetative remediation [4, 5]. Therefore, the word is relating the technology for the management of environmental problems using plants and their allied microorganisms.

Many observes, phytoremediation, especially when very toxic materials are in request (e.g., radioactive waste). Phytoremediation is a general term refers to a set of plant–contaminant interactions, and a precise application procedure involved in remediation of radioactively contaminated locations. Most of these practices involve applying information known for decades in agriculture and ecology to environmental problems. Basic information of phytoremediation comes from several research areas; containing ecotoxicology, plant ecophysiology, agriculture, toxicity and translocation of toxic radioactive isotopes.

Mitigation of the environmental pollutant challenges with excavating the contaminants, dispose them off somewhere else with a cost-effective and an environmentally

friendly technique in waters and soils purification even in heavy metals [2, 3]. The conventional remediation techniques like chemical, thermal, physical and other treatment methods are costly, and may cause more contaminations to the environments [4].

The International Atomic Energy Agency (IAEA) has clearly defined radioactive waste as those materials that emits radioactive particles comprise intensities greater than the prescribed benign on national and international standards, and no additional use is expected [5–7]. For instance, hazardous radioactive waste is produced at each stage of the nuclear (uranium) fuel cycle with no nuclear waste facility. So, there is an immediate need of permanent storage facilities as well as repositories for the high-level nuclear wastes. Radioactive waste can be solid, liquid or gas from a diverse group of operations and activities (mining to nuclear power) and accidents poses health risks and has the potential to interrupt ecosystems.

Phytoremediation of radioactive waste is a method that uses plants to remove, transfer, or immobilize radionuclides present in the contaminated soil, water, or sludge, and it is a useful method for treating large-scale but low-level radionuclide pollution. Radioactive materials provide numerous applications (scientific, medical, agricultural, industrial and energy generation) and play a significant role in daily life in human society. Consequently, it is predictable that such diverse actions lead to radioactive waste generation. The nuclear accident at Chernobyl, Ukraine alone has been calculated to have increased the risk of cancer to humans by 0.1% [2, 8].

Radioactive uranium (U), caesium (Cs), strontium (Sr), and plutonium (Pu) are the main radioactive isotopes present in the environment as a consequence of nuclear activities, and are the radionuclides of most concern (for a list of radionuclides of environmental and health concern. Sometime the radioactive wastes have military applications, e.g., depleted uranium is used in weaponries, and the spent nuclear fuel (from reactors) comprise weapons-usable plutonium. Nuclear waste containing short radiation, generally of little concern as it fades quickly by natural radioactive decay. Conversely medium-level long-lived and high-level radioactive nuclear waste is more challenging and benign disposal of this waste is essential. Most of the nuclear waste produced in nuclear power plants, (half-life and effects of environmentally dangerous radioactive isotopes are listed in **Table 1**).

In specific, the prerequisite for the concern is for spent (used) radioactive fuel recently removed from nuclear reactors. Moreover, there is an alarming accumulation of radioactive material cast in glass or ceramics, shielded in stainless steel containers which is held in dry storage across the world [10, 11]. So, radioactive waste needs to be managed in a safe and must be remote from people till it remains dangerous.


**31**

*Phytoremediation of Hazardous Radioactive Wastes DOI: http://dx.doi.org/10.5772/intechopen.88055*

radioactive waste are as follow:

determined.

Radionuclides waste sources are transported in soil, sediments, or sludges can be reduced over and done with absorption and accumulation by the plant roots; adsorption onto roots; precipitation, or reduction in soil with root zone; or binding to humic (organic) matter by the process of humification. Before phytoremediation of the concerned radioactive waste, the appropriate natural plant should be wisely selected. The ways for selection the right plant species for phytoremediation of the

3.Then, the concentration of a concerned radionuclide in the plant should be

5.Lastly, the concentration of a goal radionuclide in the remediated radioactive

Phytoremediation of radioactive waste is a worthwhile technique for treating large-scale, but low-level radionuclide waste. However, from the above mentioned criteria we can screen out the right plant types proficient to remediate the concerned radioactive waste. In the present chapter, significant features prompting the choice of natural plant to remediate radioactive waste. The concentration and features of radioactive waste, the plant type and plant structure, deposited area are detected, and the standards based on the phytoremediation factor (PF) have been anticipated for the selection of natural plant to phytoremediate radioactive waste.

Radioactive waste is distinct radioactive material for which no further use is foreseen in gaseous, liquid or solid form and controlled by a regulatory organization. According to international law governed by IAEA, spent nuclear fuel is not defined as wastes are well-defined by the accountable country. The wastes are categorized by the type and concentration of radioactive particles emitted (α, β and γ), energy and heat generation. The latest waste classification system for radioactive waste has been approved in universal standards established by the IAEA and are

**Exempt waste (EW):** It comprises such a low concentration of radionuclides that create negligible radiological hazards and it can be excluded from nuclear

**Very short lived waste (VSLW):** These types of wastes are often treated to achieve volume reduction and/or conditioned, stored for decay over a limited period of few years, prior to disposal. These are disposed of as regular industrial waste and consequently cleared of regulatory control [12, 13]. Further, various safe and effective treatment routes are open, with chemical precipitation as well as

**Very low level waste (VLLW):** It does not require isolation and a high level of containment, and disposal is done in near-surface landfill. VLLW wastes are always cured to attain liquidity (volume) reduction and waste is immobilized prior to its

1.Primarily, the features of radioactive waste should be examined.

2.Next, the plant class and its composition should be recorded.

4.The plant biomass should be considered, and

waste should be restrained.

**2. Classification of radioactive wastes**

explained as follows [7]:

regulatory control.

incineration.

#### **Table 1.**

*Phytoremediation of radioactive metals [9].*

#### *Phytoremediation of Hazardous Radioactive Wastes DOI: http://dx.doi.org/10.5772/intechopen.88055*

*Assessment and Management of Radioactive and Electronic Wastes*

poses health risks and has the potential to interrupt ecosystems.

friendly technique in waters and soils purification even in heavy metals [2, 3]. The conventional remediation techniques like chemical, thermal, physical and other treatment methods are costly, and may cause more contaminations to the environments [4]. The International Atomic Energy Agency (IAEA) has clearly defined radioactive waste as those materials that emits radioactive particles comprise intensities greater than the prescribed benign on national and international standards, and no additional use is expected [5–7]. For instance, hazardous radioactive waste is produced at each stage of the nuclear (uranium) fuel cycle with no nuclear waste facility. So, there is an immediate need of permanent storage facilities as well as repositories for the high-level nuclear wastes. Radioactive waste can be solid, liquid or gas from a diverse group of operations and activities (mining to nuclear power) and accidents

Phytoremediation of radioactive waste is a method that uses plants to remove, transfer, or immobilize radionuclides present in the contaminated soil, water, or sludge, and it is a useful method for treating large-scale but low-level radionuclide pollution. Radioactive materials provide numerous applications (scientific, medical, agricultural, industrial and energy generation) and play a significant role in daily life in human society. Consequently, it is predictable that such diverse actions lead to radioactive waste generation. The nuclear accident at Chernobyl, Ukraine alone has been calculated to have increased the risk of cancer to humans by 0.1% [2, 8].

Radioactive uranium (U), caesium (Cs), strontium (Sr), and plutonium (Pu) are the main radioactive isotopes present in the environment as a consequence of nuclear activities, and are the radionuclides of most concern (for a list of radionuclides of environmental and health concern. Sometime the radioactive wastes have military applications, e.g., depleted uranium is used in weaponries, and the spent nuclear fuel (from reactors) comprise weapons-usable plutonium. Nuclear waste containing short radiation, generally of little concern as it fades quickly by natural radioactive decay. Conversely medium-level long-lived and high-level radioactive nuclear waste is more challenging and benign disposal of this waste is essential. Most of the nuclear waste produced in nuclear power plants, (half-life and effects of environmentally dangerous radioactive isotopes

In specific, the prerequisite for the concern is for spent (used) radioactive fuel recently removed from nuclear reactors. Moreover, there is an alarming accumulation of radioactive material cast in glass or ceramics, shielded in stainless steel containers which is held in dry storage across the world [10, 11]. So, radioactive waste needs to be managed in a safe and must be remote from people till it remains

> Explosives, mixed oxide fuel, power and heat sources. Example atomic bombings of Hiroshima and Nagasaki

Bombs, weapons, nuclear fuel Mutations, cancer, birth defects

cancer

Fire hazard, radioactivity and the heavy metal poison, radiation sickness, genetic damage, cancer, and death

Lymphoma, leukaemia, bone

**Radionuclide Half-life Uses Effects**

Thorium (232) 14 billion years Alloying agent, nuclear fuel Carcinogenic

watches

**30**

**Table 1.**

are listed in **Table 1**).

Uranium (238) 4.5 billion

*Phytoremediation of radioactive metals [9].*

years

80.8 million years

Radium (226) 1601 years Luminous paints, dials of

dangerous.

Plutonium (244)

Radionuclides waste sources are transported in soil, sediments, or sludges can be reduced over and done with absorption and accumulation by the plant roots; adsorption onto roots; precipitation, or reduction in soil with root zone; or binding to humic (organic) matter by the process of humification. Before phytoremediation of the concerned radioactive waste, the appropriate natural plant should be wisely selected. The ways for selection the right plant species for phytoremediation of the radioactive waste are as follow:


Phytoremediation of radioactive waste is a worthwhile technique for treating large-scale, but low-level radionuclide waste. However, from the above mentioned criteria we can screen out the right plant types proficient to remediate the concerned radioactive waste. In the present chapter, significant features prompting the choice of natural plant to remediate radioactive waste. The concentration and features of radioactive waste, the plant type and plant structure, deposited area are detected, and the standards based on the phytoremediation factor (PF) have been anticipated for the selection of natural plant to phytoremediate radioactive waste.

### **2. Classification of radioactive wastes**

Radioactive waste is distinct radioactive material for which no further use is foreseen in gaseous, liquid or solid form and controlled by a regulatory organization. According to international law governed by IAEA, spent nuclear fuel is not defined as wastes are well-defined by the accountable country. The wastes are categorized by the type and concentration of radioactive particles emitted (α, β and γ), energy and heat generation. The latest waste classification system for radioactive waste has been approved in universal standards established by the IAEA and are explained as follows [7]:

**Exempt waste (EW):** It comprises such a low concentration of radionuclides that create negligible radiological hazards and it can be excluded from nuclear regulatory control.

**Very short lived waste (VSLW):** These types of wastes are often treated to achieve volume reduction and/or conditioned, stored for decay over a limited period of few years, prior to disposal. These are disposed of as regular industrial waste and consequently cleared of regulatory control [12, 13]. Further, various safe and effective treatment routes are open, with chemical precipitation as well as incineration.

**Very low level waste (VLLW):** It does not require isolation and a high level of containment, and disposal is done in near-surface landfill. VLLW wastes are always cured to attain liquidity (volume) reduction and waste is immobilized prior to its

disposal [13, 14]. Several safe and effective additional treatments are available, e.g., chemical precipitation and incineration.

**Low level waste (LLW):** It covers limited amounts of long-lived radionuclides with a very wide variety of radioactive waste. Waste that does not need shielding for handling or transportation, and isolation ages of a few 100 years. LLW may be slightly contaminated with radiation; for example, paper, glassware, tools and clothing. A wide range of disposal and storage alternatives are available, from simple to complex engineered facilities, e.g., landfills or incineration.

**Intermediate level waste (ILW):** ILW (reactor components, chemical residues, used metal fuel cladding) contains long-lived radionuclides alpha (α) emitters and isolation blocks. It does not need facility of heat dissipation during storage and disposal. ILW requires special handling and shielding of radioactivity. This waste is destined for disposal in deep geological repositories (the Waste Isolation Pilot Plant in USA).

**High level waste (HLW):** HLW covers high intensities of radiations that produce major amounts of heat by radioactive degeneration. It demands the design of removal in very deep, even geological layers, typically several hundred meters below the surface. The two primary categories are: (1) used fuel rods from nuclear plants and (2) waste from reprocessing the fuel rods. The waste contains both short-lived and long-lived high radiation nucleotides (half-lives of many thousands of years) which comprises high concentrations of radioactivity and requires cooling and special shielding, handling and storage.
