be efficient. Sinha et al. (2016) reported 96% decolorization of direct red À31 dye
using Chlorella pyrenoidosa strain NCIM 2738. Microorganisms such as
Trichoderma asperellum and DDB I strain of Enterobacter cloacae have been
used in the degradation of crystal violet and hair dye, respectively (Shanmugam
et al. 2017; Maiti et al. 2017).
Pesticides that are generally used to control pests or insects to protect the crops
and improve the yield of agricultural products has become a threat to the environment. The nearby surface and groundwater bodies are also affected due to contamination with pesticides. Moreover, the management of the contaminants through the
remediation process is difficult, as they are known to be persistent in the environment (Nisha et al. 2015). Hence, the degradation of pesticides from different sources
with potential microorganisms has been implemented. Aspergillus niger AN
400 was used in degrading atrazine from wastewater, which showed 70% degradation efficiency (Marinho et al. 2017). Similarly, 46% degradation of isoproturon was
achieved in agricultural soil using the AK1 strain of Sphingomonas sp. (Li et al.
2017). The use of both pure and mixed culture of Streptomyces spp. has shown
>70% removal of organophosphate-based pesticide (chlorpyrifos) and 50% removal
of its intermediate 3,5,6-trichloro-2-pyridinol (TCP) (Briceño et al. 2016).
2 Modern Approaches in Bioremediation
2.1 Electrokinetic Bioremediation
Electrokinetic (EK) technology is used for the efficient removal of contaminants of
different types, using both in situ and ex situ processes under an electrical potential
gradient. Electrokinetic processes depend on various factors, such as the composition of the electrolyte, ionic strength, pH, electrical conductivity and field strength,
zeta potential, types and chemistry of soil, permeability and content of water, nature
of arrangement, and electrode materials (Tummala and Tewari 2018). EK involves
three phenomena, viz., electroosmosis, electromigration, and electrophoresis. Electroosmosis is the transport of liquid in a porous material from anode to cathode under
the influence of an applied electric field. It helps in the removal of uncharged organic
molecules in the matrix due to a net flux of water created in the soil pore during the
process. Electromigration involves the movement of cations toward the cathode and
the anions toward the anode. Electrophoresis is the separation or movement of
charged or dispersed particles under the influence of an electric field.
EK-remediation has been applied for the in situ treatment of less permeable soils,
and many successful works have been reported for effective removal of various
contaminants from such soils (Rodrigo et al. 2014). The EK technique has been
further enhanced, by combining with bioremediation (Table 11.1), and is considered
as a prominent approach for the treatment of contaminants in the heterogeneous
matrix. An electric field gradient is formed, when the voltage is applied to both sides
of the soil. Electrolysis in the samples produces hydrogen (H
+
) and hydroxyl (OH
À )
224
A. Murmu and M. Sevanan
using Chlorella pyrenoidosa strain NCIM 2738. Microorganisms such as
Trichoderma asperellum and DDB I strain of Enterobacter cloacae have been
used in the degradation of crystal violet and hair dye, respectively (Shanmugam
et al. 2017; Maiti et al. 2017).
Pesticides that are generally used to control pests or insects to protect the crops
and improve the yield of agricultural products has become a threat to the environment. The nearby surface and groundwater bodies are also affected due to contamination with pesticides. Moreover, the management of the contaminants through the
remediation process is difficult, as they are known to be persistent in the environment (Nisha et al. 2015). Hence, the degradation of pesticides from different sources
with potential microorganisms has been implemented. Aspergillus niger AN
400 was used in degrading atrazine from wastewater, which showed 70% degradation efficiency (Marinho et al. 2017). Similarly, 46% degradation of isoproturon was
achieved in agricultural soil using the AK1 strain of Sphingomonas sp. (Li et al.
2017). The use of both pure and mixed culture of Streptomyces spp. has shown
>70% removal of organophosphate-based pesticide (chlorpyrifos) and 50% removal
of its intermediate 3,5,6-trichloro-2-pyridinol (TCP) (Briceño et al. 2016).
2 Modern Approaches in Bioremediation
2.1 Electrokinetic Bioremediation
Electrokinetic (EK) technology is used for the efficient removal of contaminants of
different types, using both in situ and ex situ processes under an electrical potential
gradient. Electrokinetic processes depend on various factors, such as the composition of the electrolyte, ionic strength, pH, electrical conductivity and field strength,
zeta potential, types and chemistry of soil, permeability and content of water, nature
of arrangement, and electrode materials (Tummala and Tewari 2018). EK involves
three phenomena, viz., electroosmosis, electromigration, and electrophoresis. Electroosmosis is the transport of liquid in a porous material from anode to cathode under
the influence of an applied electric field. It helps in the removal of uncharged organic
molecules in the matrix due to a net flux of water created in the soil pore during the
process. Electromigration involves the movement of cations toward the cathode and
the anions toward the anode. Electrophoresis is the separation or movement of
charged or dispersed particles under the influence of an electric field.
EK-remediation has been applied for the in situ treatment of less permeable soils,
and many successful works have been reported for effective removal of various
contaminants from such soils (Rodrigo et al. 2014). The EK technique has been
further enhanced, by combining with bioremediation (Table 11.1), and is considered
as a prominent approach for the treatment of contaminants in the heterogeneous
matrix. An electric field gradient is formed, when the voltage is applied to both sides
of the soil. Electrolysis in the samples produces hydrogen (H
+
) and hydroxyl (OH
À )
224
A. Murmu and M. Sevanan