ubiquitously found in tar, oil, petroleum products, and coal deposits (Mueller et al.
1996). Reports are available on the removal of organic pollutants such as
pentadecane, phenol, pentachlorophenol, creosote, and diesel in laboratory-,
bench-, and field-scale experiments under an electric field (Lear et al. 2004; Luo
et al. 2005). The organic pollutants can be classified as polar or nonpolar compounds. The polar organic compounds can be removed by an introduced direct
current that can lead to the removal/migration of pollutants by the EK phenomena
(Wick et al. 2004). Earlier, the non-polar organic pollutants could be removed only
by an electro-osmosis process. Later, some researchers achieved the removal of
nonpolar organic pollutants in the heterogeneous matrix by using different types of
surfactants such as Brij 35 (Wick et al. 2004) and Triton X-100 (Lahlou et al. 2000).
Wick and his group (Wick et al. 2004) studied EK transport of PAH-degradation
bacteria in model aquifers and soil. They demonstrated that electro-osmosis is a
valuable mechanism to transport bacteria in the subsurface, with transport efficiencies heavily depending on the retention of the bacteria by the solid phase. The
weakly negative charged bacterial strains (L138, LB501TG) were highly transported
by electro-osmosis and electrophoresis (0–20% only). The poor EK transport of
strongly charged and highly adhesive bacterial cells in the matrix is enhanced by the
addition of a non-ionic surfactant.
5.2.2 Reactive Dyes
The combined bio-EK technology was developed to accelerate the uniform transport
of microorganisms in the removal of organic pollutants (polychloroethylene, trichloroethylene) that are capable of degradation of pollutants present in the soil (Hassan
et al. 2016). Lear et al. (2004) explained that the impressed voltage/current does not
have a direct effect on soil microorganism and also soil health will be improved by
factors such as soil pH, bacterial physiology, and temperature. To the present, only
one work on the influence of direct current (DC) on the bacterially mediated
degradation of textile dye organic molecules and salts present in contaminated soil
has been reported (Annamalai et al. 1984/DEL/2014). The electric field was used as
a tool to inject the bacteria cells into the contaminated soil to enhance bacterially
mediated organic degradation. The bacterial strains Brevibacterium halotolerans,
Achrosomonas sp. (cellulase-, amylase-, and laccase positive), Bacillus subtilis
(cellulase- and amylase positive), and Pseudomonas aeruginosa were used in this
study to enhance the degradation of organic compounds in the soil. The bacteria in
different soil sections were enumerated during the process shown in Fig. 8.4.
The increase in the bacterial count was altered at various soil sections at different
time intervals. After the seventh day of electro-bio-stimulation (EBS), the bacterial
count at the cathode section reached the same level as in the anode side, which
indicates the flow of bacterial cells from the anode compartment to the cathode
compartment. The bacterial mobility was mediated through the electro-osmosis
process (Harms and Wick 2006; Liu et al. 1999). There was a significant increase
in the bacterial count at the top layer of the middle section while the bacterial growth
200
S. Annamalai and M. Sundaram
1996). Reports are available on the removal of organic pollutants such as
pentadecane, phenol, pentachlorophenol, creosote, and diesel in laboratory-,
bench-, and field-scale experiments under an electric field (Lear et al. 2004; Luo
et al. 2005). The organic pollutants can be classified as polar or nonpolar compounds. The polar organic compounds can be removed by an introduced direct
current that can lead to the removal/migration of pollutants by the EK phenomena
(Wick et al. 2004). Earlier, the non-polar organic pollutants could be removed only
by an electro-osmosis process. Later, some researchers achieved the removal of
nonpolar organic pollutants in the heterogeneous matrix by using different types of
surfactants such as Brij 35 (Wick et al. 2004) and Triton X-100 (Lahlou et al. 2000).
Wick and his group (Wick et al. 2004) studied EK transport of PAH-degradation
bacteria in model aquifers and soil. They demonstrated that electro-osmosis is a
valuable mechanism to transport bacteria in the subsurface, with transport efficiencies heavily depending on the retention of the bacteria by the solid phase. The
weakly negative charged bacterial strains (L138, LB501TG) were highly transported
by electro-osmosis and electrophoresis (0–20% only). The poor EK transport of
strongly charged and highly adhesive bacterial cells in the matrix is enhanced by the
addition of a non-ionic surfactant.
5.2.2 Reactive Dyes
The combined bio-EK technology was developed to accelerate the uniform transport
of microorganisms in the removal of organic pollutants (polychloroethylene, trichloroethylene) that are capable of degradation of pollutants present in the soil (Hassan
et al. 2016). Lear et al. (2004) explained that the impressed voltage/current does not
have a direct effect on soil microorganism and also soil health will be improved by
factors such as soil pH, bacterial physiology, and temperature. To the present, only
one work on the influence of direct current (DC) on the bacterially mediated
degradation of textile dye organic molecules and salts present in contaminated soil
has been reported (Annamalai et al. 1984/DEL/2014). The electric field was used as
a tool to inject the bacteria cells into the contaminated soil to enhance bacterially
mediated organic degradation. The bacterial strains Brevibacterium halotolerans,
Achrosomonas sp. (cellulase-, amylase-, and laccase positive), Bacillus subtilis
(cellulase- and amylase positive), and Pseudomonas aeruginosa were used in this
study to enhance the degradation of organic compounds in the soil. The bacteria in
different soil sections were enumerated during the process shown in Fig. 8.4.
The increase in the bacterial count was altered at various soil sections at different
time intervals. After the seventh day of electro-bio-stimulation (EBS), the bacterial
count at the cathode section reached the same level as in the anode side, which
indicates the flow of bacterial cells from the anode compartment to the cathode
compartment. The bacterial mobility was mediated through the electro-osmosis
process (Harms and Wick 2006; Liu et al. 1999). There was a significant increase
in the bacterial count at the top layer of the middle section while the bacterial growth
200
S. Annamalai and M. Sundaram