The ex situ bioremediation is a biological process in which excavated soil is
placed in a lined aboveground treatment area and aerated following processing to
enhance the degradation of organic contaminants by indigenous microbial population. This process is further divided into slurry-phase bioremediation and solid-phase
bioremediation. Slurry-phase process is a controlled treatment that involves the
excavation of the contaminants soil, mixing it with water and placing it in a
bioreactor to form slurry. Subsequently, soil is removed, dried up, deposited and
finally treatment of the resulting fluids. Solid-phase bioremediation is a technology
in which the contaminated soil is excavated and placed into piles. Bacterial growth is
stimulated through a network of pipes that are distributed throughout the piles.
Necessary ventilation is provided for microbial respiration through the pipes by
pulling air. This system requires a large amount of space, and cleanup requires more
time to complete than with slurry-phase processes. Some solid-phase treatment
processes include soil biopile, composting and land farming. The ex situ method is
suitable for a wide range of contaminants but is not applicable to heavy metal
contaminants or chlorinated hydrocarbons.
12.5 Potential of Extremophiles for Bioremediation
The ability of extremophilic microorganisms to grow under a wide range of extreme
conditions makes them good candidates for bioremediation. The biological processes have many advantages from environmental, economic and practical aspects
to remediate polluted sites. The immobilization, mobilization and/or transformation
of metals/metalloids and adsorption and biodegradation of organic contaminants are
the main remediation processes that can be mediated by the action of several
microorganisms especially extremophiles surviving in harsh environments with
high concentrations of pollutants (Donati et al. 2019). The extremophilic microorganisms have proved to be useful for bioremediation applications. Different kinds of
wastes and contaminants are produced from the industrial activities, the mining
activities for oils extraction or the accidental oil spills. All these activities release
several pollutants in the environments such as hydrocarbons, polycyclic aromatic
hydrocarbons, chlorinated hydrocarbons, pesticides and heavy metals (Sivaperumal
et al. 2017). Removal and detoxification of these contaminants and wastes can be
achieved by means of extremozymes which have unique properties such as high
thermostability and resistance to denaturing agents like detergents, organic solvents
and extreme pH (Castillo et al. 2005). Hence, there is an increasing interest in the
optimization of bioremediation approaches in high salt environments, high temperature and extreme pH ranges (Table 12.3). In this sense, haloarchaea have been
successfully tested for biotechnological applications (Arora et al. 2014; Oren 2010;
Bonete and Martinez-Espinosa 2011). Recently, Marques (2018) reviewed about the
extremophiles as microfactories which are able to provide metabolic or genetic
mechanisms as controlled services to cleanup of environmental pollution. A most
recent research review on polyextremophilic microorganisms isolated from a wide
12 Potential of Extremophiles for Bioremediation
305
placed in a lined aboveground treatment area and aerated following processing to
enhance the degradation of organic contaminants by indigenous microbial population. This process is further divided into slurry-phase bioremediation and solid-phase
bioremediation. Slurry-phase process is a controlled treatment that involves the
excavation of the contaminants soil, mixing it with water and placing it in a
bioreactor to form slurry. Subsequently, soil is removed, dried up, deposited and
finally treatment of the resulting fluids. Solid-phase bioremediation is a technology
in which the contaminated soil is excavated and placed into piles. Bacterial growth is
stimulated through a network of pipes that are distributed throughout the piles.
Necessary ventilation is provided for microbial respiration through the pipes by
pulling air. This system requires a large amount of space, and cleanup requires more
time to complete than with slurry-phase processes. Some solid-phase treatment
processes include soil biopile, composting and land farming. The ex situ method is
suitable for a wide range of contaminants but is not applicable to heavy metal
contaminants or chlorinated hydrocarbons.
12.5 Potential of Extremophiles for Bioremediation
The ability of extremophilic microorganisms to grow under a wide range of extreme
conditions makes them good candidates for bioremediation. The biological processes have many advantages from environmental, economic and practical aspects
to remediate polluted sites. The immobilization, mobilization and/or transformation
of metals/metalloids and adsorption and biodegradation of organic contaminants are
the main remediation processes that can be mediated by the action of several
microorganisms especially extremophiles surviving in harsh environments with
high concentrations of pollutants (Donati et al. 2019). The extremophilic microorganisms have proved to be useful for bioremediation applications. Different kinds of
wastes and contaminants are produced from the industrial activities, the mining
activities for oils extraction or the accidental oil spills. All these activities release
several pollutants in the environments such as hydrocarbons, polycyclic aromatic
hydrocarbons, chlorinated hydrocarbons, pesticides and heavy metals (Sivaperumal
et al. 2017). Removal and detoxification of these contaminants and wastes can be
achieved by means of extremozymes which have unique properties such as high
thermostability and resistance to denaturing agents like detergents, organic solvents
and extreme pH (Castillo et al. 2005). Hence, there is an increasing interest in the
optimization of bioremediation approaches in high salt environments, high temperature and extreme pH ranges (Table 12.3). In this sense, haloarchaea have been
successfully tested for biotechnological applications (Arora et al. 2014; Oren 2010;
Bonete and Martinez-Espinosa 2011). Recently, Marques (2018) reviewed about the
extremophiles as microfactories which are able to provide metabolic or genetic
mechanisms as controlled services to cleanup of environmental pollution. A most
recent research review on polyextremophilic microorganisms isolated from a wide
12 Potential of Extremophiles for Bioremediation
305