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Biology and Biotechnology of Environmental Stress Tolerance in Plants, Volume 3

1.3.1.2.1 Bioventing

The process of bioventing is an approach to aerating the water and soil

that accelerate the process of degradation of organic substances (Hyman &

Dupont, 2001). The aforementioned method is used mainly for the purpose

of the treatment of the unsaturated soils and enables aeration in the soil.

This method supplies oxygen to the microbes which are present in the water

and soil, thereby accelerating the activity of microbes. This process also

enhances the growth of the indigenous microbes that help in the decomposi­

tion of organic matter. This methodology helps to enhance the degradation

of the anaerobically degradable polluted soil which are rich in organic

hydrocarbon, pesticides, and other chemicals (Dupont, 1993; Khan, Husain,

& Hejazi, 2004). However, this process is not successful if the water table is

situated within a few feet under the soil (Van Deuren et al., 2002).

1.3.1.2.2 Biosparging

The aforementioned method is generally used to degrade the products

which are mainly composed of petroleum and also dissolved in water. The

majority of the petroleum product is absorbed by the water table in soil, so

this methodology is very much helpful (Norris, 1993, 1995). In this method,

the atmospheric air is injected through the soil which is both saturated and

unsaturated soil. To have the application of this method efficiently, the soil

should be homogenous in the polluted region. The biosparging method has

also been used to reduce energy consumption (Dary et al., 2010).

1.3.1.2.3 Bioaugmentation

The process of bioaugmentation is achieved by the addition of laboratory-

grown microbes which has the potential for degradation of the heavy metal

pollutant. In the aforementioned process, the microbial strain with higher

Polycyclic Aromatic Hydrocarbon (PAH)-degrading capabilities were inocu­

lated in the polluted soil environment (Dhanya & Kalia, 2020). This approach

introduces either wild type or genetically engineered microbes which help

to enhance the degradation of heavy metal and reclaim the soil (Kuiper et

al., 2004). There are various advances in the bioaugmentation method which

includes gene bioaugmentation, cell encapsulation, phyto-augmentation, and

rhizosphere bioaugmentation (Gentry, Rensing, & Pepper, 2004).