reduced by the acidic and basic nature in electrolyte compartments that hinder the
mobility of the pollutant ions. They concluded that the pH value of the soil matrix is
pivotal to achieving complete remediation and that K 2 SO 4 favored high electrical
conductivity. Desorption of RB5 in the model soil matrix and decolorization were
achieved in the electrolyte compartment.
Ricart et al. (2008) efficiently removed both RB 5 and Cr (III) ion from a model
kaolinite soil using EK remediation. The four sulfonic groups were neutralized and
formed four negative charge anions at alkaline pH. The negative charge of the RB5
moved towards the anode by the electromigration process. It was found that Cr was
transported towards the cathode by electromigration and electro-osmosis. The interaction among RB5 and Cr in the kaolinite sample prevented premature precipitation
and allowed Cr to migrate and concentrate in the cathode chamber.
Normally, reactive dyes are water soluble and therefore are functionalized with
the sodium salt of sulfonate ion. In the alkaline condition, reactive dyes are ionized
into weak acids that easily favor the mobility of ions by the electromigration process.
Ammonium acetate is an electrolyte that reacts with metal ions, forming metal
acetate. The metal acetate is easily ionized and moves towards the opposite direction.
Similarly, Annamalai et al. (2016) conducted a bench-scale test to evaluate the EK
process for in situ formation of electroactive species (OH˙) at the anode, which
enhanced the organic degradation (68%) in a real contaminated soil. Hence, a
suitable technology is needed to improve efficiency for the removal of dye components in the agricultural soil.
3 Bioremediation of Polluted Soils
Many research articles have addressed the treatment of organic pollutants in soil and
sediment by using autochthonous microorganisms such as Ochrobactrum
intermedium (Khan et al. 2014), Saccharomyces cerevisiae (Jadhav and Govindwar
2006), Kluyveromyces marxianus (Bustard et al. 1998), Pseudomonas aeruginosa
(Bhatt et al. 2005), and Sphingomona sp. strain BN6 (Keck et al. 1997). Bioremediation is an eco-friendly technique for pollutants treatment and it is considered to be
an effective environmental clean-up technology as compared to the conventional
methods. Moreover, it is a pollution-free/control technology for degradation of toxic
pollutants converted into less harmful products or mineralization. However, the
microbial activity may require an additional supply of nutrients, appropriate electron
acceptors, or establishment of suitable soil pH and temperature. Schäfer et al. (1998)
reported that the success of bioremediation approaches may be reduced by the low
contact probability of contamination and microorganisms as a result of the heterogeneity of the soil matrix. Later, Alexander (2000) explained the highly homogeneous nature of the polluted soil arising from diffuse pollution, which easily
associated with micro-colonies of microbes within the soil/solid matrix. Bosma
et al. (1996) calculated that the average distance between bacterial micro-colonies
in soil was in the range of 50 to 100 μm, whereas in homogeneous soil pollution it
was likely to be in the sub-millimeter range. Generally, two types of bioremediation
196
S. Annamalai and M. Sundaram
mobility of the pollutant ions. They concluded that the pH value of the soil matrix is
pivotal to achieving complete remediation and that K 2 SO 4 favored high electrical
conductivity. Desorption of RB5 in the model soil matrix and decolorization were
achieved in the electrolyte compartment.
Ricart et al. (2008) efficiently removed both RB 5 and Cr (III) ion from a model
kaolinite soil using EK remediation. The four sulfonic groups were neutralized and
formed four negative charge anions at alkaline pH. The negative charge of the RB5
moved towards the anode by the electromigration process. It was found that Cr was
transported towards the cathode by electromigration and electro-osmosis. The interaction among RB5 and Cr in the kaolinite sample prevented premature precipitation
and allowed Cr to migrate and concentrate in the cathode chamber.
Normally, reactive dyes are water soluble and therefore are functionalized with
the sodium salt of sulfonate ion. In the alkaline condition, reactive dyes are ionized
into weak acids that easily favor the mobility of ions by the electromigration process.
Ammonium acetate is an electrolyte that reacts with metal ions, forming metal
acetate. The metal acetate is easily ionized and moves towards the opposite direction.
Similarly, Annamalai et al. (2016) conducted a bench-scale test to evaluate the EK
process for in situ formation of electroactive species (OH˙) at the anode, which
enhanced the organic degradation (68%) in a real contaminated soil. Hence, a
suitable technology is needed to improve efficiency for the removal of dye components in the agricultural soil.
3 Bioremediation of Polluted Soils
Many research articles have addressed the treatment of organic pollutants in soil and
sediment by using autochthonous microorganisms such as Ochrobactrum
intermedium (Khan et al. 2014), Saccharomyces cerevisiae (Jadhav and Govindwar
2006), Kluyveromyces marxianus (Bustard et al. 1998), Pseudomonas aeruginosa
(Bhatt et al. 2005), and Sphingomona sp. strain BN6 (Keck et al. 1997). Bioremediation is an eco-friendly technique for pollutants treatment and it is considered to be
an effective environmental clean-up technology as compared to the conventional
methods. Moreover, it is a pollution-free/control technology for degradation of toxic
pollutants converted into less harmful products or mineralization. However, the
microbial activity may require an additional supply of nutrients, appropriate electron
acceptors, or establishment of suitable soil pH and temperature. Schäfer et al. (1998)
reported that the success of bioremediation approaches may be reduced by the low
contact probability of contamination and microorganisms as a result of the heterogeneity of the soil matrix. Later, Alexander (2000) explained the highly homogeneous nature of the polluted soil arising from diffuse pollution, which easily
associated with micro-colonies of microbes within the soil/solid matrix. Bosma
et al. (1996) calculated that the average distance between bacterial micro-colonies
in soil was in the range of 50 to 100 μm, whereas in homogeneous soil pollution it
was likely to be in the sub-millimeter range. Generally, two types of bioremediation
196
S. Annamalai and M. Sundaram