Depending on the enzymatic capability of the microorganisms, they may be able
to degrade contaminants of various properties (linear, branched or cyclic alkanes,
mono-or polynuclear aromatics). With the assistance of biotechnological techniques,
various studies are being carried out to select the microorganisms with the potential
to degrade the compounds with toxic nature.
Microbial strains or consortia, which are acclimatized to the contamination site,
lead to the successful bioaugmentation. Without the ability to compete with the
indigenous microbes, predators and various abiotic factors of a particular microbe
cannot succeed in carrying out the process of degradation. For the screening of
microbe, it is also important to study the chemical structure and concentration of
pollutants along with the availability of the contaminant to the microorganisms, the
size and nature of microbial population and physical environment (Adams et al.
2015).
There is also a section of degradation which occurs only when oxygen is absent.
Conversion of organic parts of degradable organic solid waste and refuse into biogas
comprises of methane and carbon dioxide and a humus-like material by anaerobic
bacteria like methanogens (methane-producing archeobacteria). This process is
called Dranco process, which has been followed by countries like Brecht, Belgium
and Salzburg, Austria (Katyayan 2019).
Nitrate is removed from water by the introduction of methylotrophic bacteria like
Methylophilus methylotrophus to carry out the process of denitrification (Katyayan
2019). Eutrophication can be prevented by the removal of nitrate from waste water
(Sharma 2016).
With the addition of methanol to bioreactor, growth of methylotrophs can be
enhanced. To biodegrade chlorinated hydrocarbons present in effluents of pesticide
industries, which manufacture DDT, heptachlor, chlordane, etc., bacteria like Pseudomonas cepacia are utilized. In Hong Kong, Acetobacter liquefaciens S-1 is used to
treat waste water in textile and dye industries.
Multiple microbial communities are grown in bioscrubbers and biotrickling
filters, to produce multilayered complexes called biofilms. Organic pollutants,
along with gas streams, are passed through biofilms/biofilters, and the pollutants
can be easily degraded. Due to great network area of fungal mycelia, greater surface
area is created, thereby elimination of pollutants is done to a greater capacity. Thus
fungus like Candida tropicalis is used to treat volatile organic compounds in air.
Biofilters are used to eliminate ethanol and isopropyl alcohol, which are released into
air while drying ceramics. The injection of air to stimulate and aerobic degradation
and volatization is called air sparging. The contaminated water is pumped to the
surface and then is reinjected which is called bioventing. Microbes like Thiobacillus
ferrooxidans conduct metal solubilization or leaching to recover Cu, Pb, Zn and Ur
through metal solubilization (Table 3.1) (Katyayan 2019).
3 Microbial Indicators of Bioremediation: Potential and Success
91
to degrade contaminants of various properties (linear, branched or cyclic alkanes,
mono-or polynuclear aromatics). With the assistance of biotechnological techniques,
various studies are being carried out to select the microorganisms with the potential
to degrade the compounds with toxic nature.
Microbial strains or consortia, which are acclimatized to the contamination site,
lead to the successful bioaugmentation. Without the ability to compete with the
indigenous microbes, predators and various abiotic factors of a particular microbe
cannot succeed in carrying out the process of degradation. For the screening of
microbe, it is also important to study the chemical structure and concentration of
pollutants along with the availability of the contaminant to the microorganisms, the
size and nature of microbial population and physical environment (Adams et al.
2015).
There is also a section of degradation which occurs only when oxygen is absent.
Conversion of organic parts of degradable organic solid waste and refuse into biogas
comprises of methane and carbon dioxide and a humus-like material by anaerobic
bacteria like methanogens (methane-producing archeobacteria). This process is
called Dranco process, which has been followed by countries like Brecht, Belgium
and Salzburg, Austria (Katyayan 2019).
Nitrate is removed from water by the introduction of methylotrophic bacteria like
Methylophilus methylotrophus to carry out the process of denitrification (Katyayan
2019). Eutrophication can be prevented by the removal of nitrate from waste water
(Sharma 2016).
With the addition of methanol to bioreactor, growth of methylotrophs can be
enhanced. To biodegrade chlorinated hydrocarbons present in effluents of pesticide
industries, which manufacture DDT, heptachlor, chlordane, etc., bacteria like Pseudomonas cepacia are utilized. In Hong Kong, Acetobacter liquefaciens S-1 is used to
treat waste water in textile and dye industries.
Multiple microbial communities are grown in bioscrubbers and biotrickling
filters, to produce multilayered complexes called biofilms. Organic pollutants,
along with gas streams, are passed through biofilms/biofilters, and the pollutants
can be easily degraded. Due to great network area of fungal mycelia, greater surface
area is created, thereby elimination of pollutants is done to a greater capacity. Thus
fungus like Candida tropicalis is used to treat volatile organic compounds in air.
Biofilters are used to eliminate ethanol and isopropyl alcohol, which are released into
air while drying ceramics. The injection of air to stimulate and aerobic degradation
and volatization is called air sparging. The contaminated water is pumped to the
surface and then is reinjected which is called bioventing. Microbes like Thiobacillus
ferrooxidans conduct metal solubilization or leaching to recover Cu, Pb, Zn and Ur
through metal solubilization (Table 3.1) (Katyayan 2019).
3 Microbial Indicators of Bioremediation: Potential and Success
91