4.5
Technologies Involved in Bioremediation
4.5.1 Biorestoration
A number of specific terms are used to describe the activity of MOs and the ways in
which they are used in bioremediation: Biodegradation is the breakage or fragmentation of a compound or substance produced by living organisms, bacteria, or fungi
that may be indigenous to that area or can be entered. Biostimulation is the method
by which the populations of MOs, whether natural or introduced, are enhanced by
nutritional, engineering, or other area preparation work. This increases the speed of
natural remediation processes. Bioaugmentation is the method by which specific
living organisms are added to a site or material to achieve a desired bioremediation
effect. Biorestoration is the restoration of the original state or of a state close to the
original state by the use of living MOs.
Bioremediation technologies can be applied locally (“in situ”) or “ex situ”
(by transporting the polluted substrate to special treatment facilities). The technology
used to treat a polluted site is site-dependent and pollutant-dependent. Bioremediation can be done through biological extraction of HMs by plant and MOs and
biodegradation of pollutants from soil contaminated by MOs and plants. Knowledge
of microbial communities is constantly developing in the process of developing
advanced bioremediation technologies. MOs play a role in the circuit of chemical
elements and nutrients as matter and energy globally through their great EAs over
substances. These EAs have been recognized as a way of biodegradation and
removal of environmentally harmful anthropogenic residues.
Research in this field addresses the deeper knowledge of the role and ecology of
plants useful for depollution. MOs have developed a variety of biochemical
pathways to degrade or detoxify soils. Hydrolase and oxygenase are the most
important classes of enzymes, which are responsible for catalyzing biotransformation reactions. Changes in microbial communities during bioremediation can be
determined using molecular and genetic microbiology methods in researching the
various roles of MOs. Soil MOs activity is influenced by the presence of
microhabitats, soil type, structure and texture, assurance of OM and nutrients, and
environmental factors (Liu et al. 2018a, b).
4.5.2 Bioremediation with Microbial Communities
Transformation of metals under the action of MOs is a key link of metal cycles in the
biosphere. Metal transformations are dominated by oxidoreduction reactions, the
complexation of organic and inorganic compounds, and the change between water
soluble and water-insoluble forms. When a MO oxidizes or reduces a metal, it
precipitates or becomes soluble. For example: Cr
6+ is reduced to Cr
3+ , which
precipitates as oxides, sulfides, or chromates of phosphate. Bacteria living in high
metallic environments have specific physiological mechanisms that allow them to
survive under these unsuitable conditions: extracellular precipitation, binding of
4 Advanced Technologies for Ecological Reconstruction and Bioremediation of. . .
95
Technologies Involved in Bioremediation
4.5.1 Biorestoration
A number of specific terms are used to describe the activity of MOs and the ways in
which they are used in bioremediation: Biodegradation is the breakage or fragmentation of a compound or substance produced by living organisms, bacteria, or fungi
that may be indigenous to that area or can be entered. Biostimulation is the method
by which the populations of MOs, whether natural or introduced, are enhanced by
nutritional, engineering, or other area preparation work. This increases the speed of
natural remediation processes. Bioaugmentation is the method by which specific
living organisms are added to a site or material to achieve a desired bioremediation
effect. Biorestoration is the restoration of the original state or of a state close to the
original state by the use of living MOs.
Bioremediation technologies can be applied locally (“in situ”) or “ex situ”
(by transporting the polluted substrate to special treatment facilities). The technology
used to treat a polluted site is site-dependent and pollutant-dependent. Bioremediation can be done through biological extraction of HMs by plant and MOs and
biodegradation of pollutants from soil contaminated by MOs and plants. Knowledge
of microbial communities is constantly developing in the process of developing
advanced bioremediation technologies. MOs play a role in the circuit of chemical
elements and nutrients as matter and energy globally through their great EAs over
substances. These EAs have been recognized as a way of biodegradation and
removal of environmentally harmful anthropogenic residues.
Research in this field addresses the deeper knowledge of the role and ecology of
plants useful for depollution. MOs have developed a variety of biochemical
pathways to degrade or detoxify soils. Hydrolase and oxygenase are the most
important classes of enzymes, which are responsible for catalyzing biotransformation reactions. Changes in microbial communities during bioremediation can be
determined using molecular and genetic microbiology methods in researching the
various roles of MOs. Soil MOs activity is influenced by the presence of
microhabitats, soil type, structure and texture, assurance of OM and nutrients, and
environmental factors (Liu et al. 2018a, b).
4.5.2 Bioremediation with Microbial Communities
Transformation of metals under the action of MOs is a key link of metal cycles in the
biosphere. Metal transformations are dominated by oxidoreduction reactions, the
complexation of organic and inorganic compounds, and the change between water
soluble and water-insoluble forms. When a MO oxidizes or reduces a metal, it
precipitates or becomes soluble. For example: Cr
6+ is reduced to Cr
3+ , which
precipitates as oxides, sulfides, or chromates of phosphate. Bacteria living in high
metallic environments have specific physiological mechanisms that allow them to
survive under these unsuitable conditions: extracellular precipitation, binding of
4 Advanced Technologies for Ecological Reconstruction and Bioremediation of. . .
95