of the reagents can be used combining them with ultraviolet oxidation. In the
reduction processes of unsaturated organic contaminants or high oxidation state
metals like Cr (VI), metals with low oxidation potential or sodium borohydride are
generally used.
The chemistry involved in this method is generally well known, and it has been
used for years in related chemical processes. But the main drawback of this method
is the requirement of excessive amount of reagents making it costly for high
contaminant concentrations, and partial decontamination may result along with
formation of intermediate contaminants.
3.1.5 Solidification
This is the method of stabilizing the contaminant by physical bound or enclosing
within a low permeability mass, i.e., solidification. The mobility is reduced by the
induction of chemical reaction between contaminant and stabilizing agent. This
technique can be applied ex situ as well as in situ but requires additional setups.
Inorganics, including radionuclides, are mostly treated by this method, whereas it
has less effectiveness against organics and pesticides.
The main disadvantage in the application of this technique is generation of higher
final mass of pollutants than the original contaminated soil, and contaminants are
neither eliminated nor transformed into less toxic form, and only mobility is reduced.
3.1.6 Chemical Extraction
In this process, contaminants are separated from the soil to reduce the volume of
contaminant. On the basis of the type of contaminants, two major chemical extraction processes are as follows:
1. Acid extraction – Acids are used to extract contaminants from soils. Additionally
after decontamination, residual acid is neutralized by dewatering of soil followed
by mixing it with fertilizer and lime.
2. Solvent extraction – To remove mixtures of metals and organic compounds,
different solvents are used in the treatment of soil. Physical separation is generally
required prior to chemical extraction, which can enhance the process by separating out particulate heavy metals.
An advantage of this technology is that it can be used for the extraction of a range
of selected organic contaminants for the treatment such as SVOCs, VOCs, some
fuels, explosives, and inorganics, heavy metals, etc. However, the effectiveness of
this technology is limited on organics with high molecular weight (eugris.info).
17 Plant-Microbe Interactions for Bioremediation and Phytoremediation of. . .
421
reduction processes of unsaturated organic contaminants or high oxidation state
metals like Cr (VI), metals with low oxidation potential or sodium borohydride are
generally used.
The chemistry involved in this method is generally well known, and it has been
used for years in related chemical processes. But the main drawback of this method
is the requirement of excessive amount of reagents making it costly for high
contaminant concentrations, and partial decontamination may result along with
formation of intermediate contaminants.
3.1.5 Solidification
This is the method of stabilizing the contaminant by physical bound or enclosing
within a low permeability mass, i.e., solidification. The mobility is reduced by the
induction of chemical reaction between contaminant and stabilizing agent. This
technique can be applied ex situ as well as in situ but requires additional setups.
Inorganics, including radionuclides, are mostly treated by this method, whereas it
has less effectiveness against organics and pesticides.
The main disadvantage in the application of this technique is generation of higher
final mass of pollutants than the original contaminated soil, and contaminants are
neither eliminated nor transformed into less toxic form, and only mobility is reduced.
3.1.6 Chemical Extraction
In this process, contaminants are separated from the soil to reduce the volume of
contaminant. On the basis of the type of contaminants, two major chemical extraction processes are as follows:
1. Acid extraction – Acids are used to extract contaminants from soils. Additionally
after decontamination, residual acid is neutralized by dewatering of soil followed
by mixing it with fertilizer and lime.
2. Solvent extraction – To remove mixtures of metals and organic compounds,
different solvents are used in the treatment of soil. Physical separation is generally
required prior to chemical extraction, which can enhance the process by separating out particulate heavy metals.
An advantage of this technology is that it can be used for the extraction of a range
of selected organic contaminants for the treatment such as SVOCs, VOCs, some
fuels, explosives, and inorganics, heavy metals, etc. However, the effectiveness of
this technology is limited on organics with high molecular weight (eugris.info).
17 Plant-Microbe Interactions for Bioremediation and Phytoremediation of. . .
421