contaminated sites use the contaminants as nutrients or energy sources. Stimulation
of microbes is achieved by the addition of growth substances, nutrients, terminal
electron acceptor or donors resulting in an increase in organic pollutant degradation
and biotransformation. Bioremediation may be employed to attack specific contaminants such as chlorinated pesticides that are degraded by microbes or a more general
approach such as oil spills that are broken down using multiple techniques.
The basic bioremediation methods include biostimulation, attenuation, augmentation, venting and piles. Biostimulation is focus on stimulation of indigenous or
naturally existing bacteria and fungus community at the site (soil/ground water)
through the injection of specific nutrients. These nutrients are the basic building
blocks of life and allow microorganism to crease the basic requirements such as
energy, biomass and enzymes to degrade the pollutants (Madhavi and Mohini 2012).
Bioattenuation or natural attenuation is the eradication of pollutant concentrations
from surrounding which is carried out using biological processes such as both
aerobic and anaerobic biodegradation, chemical reactions such as ion exchange,
complexation, abiotic transformation, and physical phenomena such as dispersion,
advection, dilution, diffusion, volatilization and sorption/desorption. Many terms
such as biotransformation or intrinsic remediation are included within the natural
attenuation or bioattenuation (Mulligana and Yong 2004). Bioaugmentation
involves the addition of pollutant-degrading microorganism (natural/exotic/
engineered) to supplement the biodegradative capacity of indigenous microbial
populations on the contaminated site. Natural species are not fast enough to break
down certain compounds, so genetically modified or extremophilic microorganisms
have potential for bioremediation of soil, groundwater, activate sludge to enhance
degrading capabilities of a broad coverage of physical and chemical pollutants
(Sayler and Ripp 2000; Thapa et al. 2012). Bioventing involves venting of oxygen
via low air flow rate through soil to simulate growth of natural or introduced bacterial
and fungus in the soil to existing soil microbes to sustain their microbial activity.
Effective bioremediation of petroleum-contaminated soil using bioinventing has
been used reported by many researchers (Lee et al. 2006; Agarry and Latinwo
2015). Biopiles (also known as bioheaps, biocells, biomounds, compost piles) is a
process to reduce concentrations of aerobically remediable petroleum pollutants in
excavated soils during the time of biodegradation. In this process, air is supplied to
the biopile system through a system of pumps and piping to enhance microbial
activity through microbial respiration (Emami et al. 2012; Kumar et al. 2016).
On the basis of removal of wastes for treatment, there are basically two types of
bioremediation—in situ and ex situ bioremediation (Table 12.2). In the former type
of bioremediation, application involves in the subsurface and may be applied in the
unsaturated zone such as bioventing or in saturated soil and groundwater. This in situ
method is a superior method for cleaning contaminated sites as it is cheaper and safer
and uses harmless microbes to degrade the harmful chemicals. This in situ bioremediation can be further categorized into intrinsic and engineered in situ bioremediation. In intrinsic in situ bioremediation, the innate capabilities of naturally occurring
microbial communities to degrade environmental pollutants are used for bioremediation. In engineered in situ bioremediation, the approach involves the introduction of
12 Potential of Extremophiles for Bioremediation
303
of microbes is achieved by the addition of growth substances, nutrients, terminal
electron acceptor or donors resulting in an increase in organic pollutant degradation
and biotransformation. Bioremediation may be employed to attack specific contaminants such as chlorinated pesticides that are degraded by microbes or a more general
approach such as oil spills that are broken down using multiple techniques.
The basic bioremediation methods include biostimulation, attenuation, augmentation, venting and piles. Biostimulation is focus on stimulation of indigenous or
naturally existing bacteria and fungus community at the site (soil/ground water)
through the injection of specific nutrients. These nutrients are the basic building
blocks of life and allow microorganism to crease the basic requirements such as
energy, biomass and enzymes to degrade the pollutants (Madhavi and Mohini 2012).
Bioattenuation or natural attenuation is the eradication of pollutant concentrations
from surrounding which is carried out using biological processes such as both
aerobic and anaerobic biodegradation, chemical reactions such as ion exchange,
complexation, abiotic transformation, and physical phenomena such as dispersion,
advection, dilution, diffusion, volatilization and sorption/desorption. Many terms
such as biotransformation or intrinsic remediation are included within the natural
attenuation or bioattenuation (Mulligana and Yong 2004). Bioaugmentation
involves the addition of pollutant-degrading microorganism (natural/exotic/
engineered) to supplement the biodegradative capacity of indigenous microbial
populations on the contaminated site. Natural species are not fast enough to break
down certain compounds, so genetically modified or extremophilic microorganisms
have potential for bioremediation of soil, groundwater, activate sludge to enhance
degrading capabilities of a broad coverage of physical and chemical pollutants
(Sayler and Ripp 2000; Thapa et al. 2012). Bioventing involves venting of oxygen
via low air flow rate through soil to simulate growth of natural or introduced bacterial
and fungus in the soil to existing soil microbes to sustain their microbial activity.
Effective bioremediation of petroleum-contaminated soil using bioinventing has
been used reported by many researchers (Lee et al. 2006; Agarry and Latinwo
2015). Biopiles (also known as bioheaps, biocells, biomounds, compost piles) is a
process to reduce concentrations of aerobically remediable petroleum pollutants in
excavated soils during the time of biodegradation. In this process, air is supplied to
the biopile system through a system of pumps and piping to enhance microbial
activity through microbial respiration (Emami et al. 2012; Kumar et al. 2016).
On the basis of removal of wastes for treatment, there are basically two types of
bioremediation—in situ and ex situ bioremediation (Table 12.2). In the former type
of bioremediation, application involves in the subsurface and may be applied in the
unsaturated zone such as bioventing or in saturated soil and groundwater. This in situ
method is a superior method for cleaning contaminated sites as it is cheaper and safer
and uses harmless microbes to degrade the harmful chemicals. This in situ bioremediation can be further categorized into intrinsic and engineered in situ bioremediation. In intrinsic in situ bioremediation, the innate capabilities of naturally occurring
microbial communities to degrade environmental pollutants are used for bioremediation. In engineered in situ bioremediation, the approach involves the introduction of
12 Potential of Extremophiles for Bioremediation
303