(i) Bioventing: The method includes regulated airflow to cause stimulation by
delivering O 2 to unsaturated zone to enhance the process of bioremediation,
by uplifting the activities of native microorganisms. The amendments in
bioventing are carried by the addition of nutrients such as nitrogen, phosphorus
and moisture for an enhancement in bioremediation with the extreme goal to
achieve the biological transformation of contaminated to a less toxic state (Niti
et al. 2013; Azubuike et al. 2016; Shah 2017). Bioventing utilizes airflow at low
rates along with only the required amount of oxygen which is necessary for
biodegrading, minimizing the volatilization and release of pollutants to the
environment. It is beneficial for simpler organic compounds which can be
used for the contaminants present deep under the surface of soil and underground water (Shah 2017). This approach is very well-designed for soils of all
types ranging from well-drained to coarse-textured (Niti et al. 2013). Bioventing
enhances the in situ bioremediation of petroleum–oil–lubricants by providing
O 2 to microbes that are present in the soil. In this system, oxygen is supplied
directly by injecting air into the residual pollution of soil. A typical bioventing
arrangement involves a well and a blower which provides aeration to the soil
through well (Shukla et al. 2010).
(j) Bioslurping: This approach combines pumping increased by vacuum, soil
vapour separation and followed by bioventing to accomplish underground
water and soil bioremediation by indirect utilization of air for inducing contaminant biodegradation. It can also be utilized to degrade volatile as well as semivolatile organic chemicals present in the polluted soils. In this process, excess of
moisture in soil limits permeability of air and decreases the rate of transfer of
oxygen which in turn reduces activities of microbes (Azubuike et al. 2016).
(k) Biosparging: This technique resembles bioventing because aeration is provided
in the subsurface of soil to stimulate activities of microbes for promoting the
removal of organic pollutants from polluted sites. The efficiency of biosparging
is majorly dependent on two factors, namely, the permeability of soil and
contaminant biodegradability (Azubuike et al. 2016). This process deals with
the exploitation of native microbes to biodegrade organic contaminants of the
soil. Biosparging technique is routinely utilized at the sites with mid-range
molecular mass petroleum refining products such as diesel oil, while lightweight
products of petroleum volatilize at a slow rate and are removed very quickly
through sparging (Das and Adholeya 2012). Biosparging enhances the
homogenizing in the saturated zone, thereby promoting its exposure between
soil and underground water (Shah 2017).
(l) Biosorption: Biosorption is one of the most significant approaches among all
methods from both the perspectives, i.e. ecological as well as practical for the
removal of metals from aqueous solution by a combination of living or dead
biomass through the usage of functionally active sites which includes carboxyl,
imidazole, sulphydryl, amino phosphate, sulphate, thioether, phenol, carbonyl,
amide and hydroxyl moieties (Whiteley and Lee 2006). The capability of
microbes to combine with metals from its aqueous solution is known as
biosorption. The components of a microorganism that bind to metals and are
430
G. Kaur et al.
delivering O 2 to unsaturated zone to enhance the process of bioremediation,
by uplifting the activities of native microorganisms. The amendments in
bioventing are carried by the addition of nutrients such as nitrogen, phosphorus
and moisture for an enhancement in bioremediation with the extreme goal to
achieve the biological transformation of contaminated to a less toxic state (Niti
et al. 2013; Azubuike et al. 2016; Shah 2017). Bioventing utilizes airflow at low
rates along with only the required amount of oxygen which is necessary for
biodegrading, minimizing the volatilization and release of pollutants to the
environment. It is beneficial for simpler organic compounds which can be
used for the contaminants present deep under the surface of soil and underground water (Shah 2017). This approach is very well-designed for soils of all
types ranging from well-drained to coarse-textured (Niti et al. 2013). Bioventing
enhances the in situ bioremediation of petroleum–oil–lubricants by providing
O 2 to microbes that are present in the soil. In this system, oxygen is supplied
directly by injecting air into the residual pollution of soil. A typical bioventing
arrangement involves a well and a blower which provides aeration to the soil
through well (Shukla et al. 2010).
(j) Bioslurping: This approach combines pumping increased by vacuum, soil
vapour separation and followed by bioventing to accomplish underground
water and soil bioremediation by indirect utilization of air for inducing contaminant biodegradation. It can also be utilized to degrade volatile as well as semivolatile organic chemicals present in the polluted soils. In this process, excess of
moisture in soil limits permeability of air and decreases the rate of transfer of
oxygen which in turn reduces activities of microbes (Azubuike et al. 2016).
(k) Biosparging: This technique resembles bioventing because aeration is provided
in the subsurface of soil to stimulate activities of microbes for promoting the
removal of organic pollutants from polluted sites. The efficiency of biosparging
is majorly dependent on two factors, namely, the permeability of soil and
contaminant biodegradability (Azubuike et al. 2016). This process deals with
the exploitation of native microbes to biodegrade organic contaminants of the
soil. Biosparging technique is routinely utilized at the sites with mid-range
molecular mass petroleum refining products such as diesel oil, while lightweight
products of petroleum volatilize at a slow rate and are removed very quickly
through sparging (Das and Adholeya 2012). Biosparging enhances the
homogenizing in the saturated zone, thereby promoting its exposure between
soil and underground water (Shah 2017).
(l) Biosorption: Biosorption is one of the most significant approaches among all
methods from both the perspectives, i.e. ecological as well as practical for the
removal of metals from aqueous solution by a combination of living or dead
biomass through the usage of functionally active sites which includes carboxyl,
imidazole, sulphydryl, amino phosphate, sulphate, thioether, phenol, carbonyl,
amide and hydroxyl moieties (Whiteley and Lee 2006). The capability of
microbes to combine with metals from its aqueous solution is known as
biosorption. The components of a microorganism that bind to metals and are
430
G. Kaur et al.