Environment has been contaminated with non biodegradable compounds due to the revolution in science and technology. Most common contaminates found in the environment are commercial hydrocarbons, gasoline, diesel, jet fuels, raw chemical compounds used in industries, benzene, toluene, ethylene, xylene, Organo-halogenated compounds like trichloroethylene, tetrachloroethane and much more. Environmental elements are also contaminated with heavy metals such as mercury, and much more.
Environment is also contaminated with non degradable chemical compounds such as,
a. Trichloroethylene : This contaminates water supply chain
b. Perchloroethylene: This compound is used as dry-cleaning agent
c. Heavy metals like arsenic, chromium and selenium
All these environmental contaminants can be degraded by using a biotechnology technique known as bioremediation.
1. Bioremediation is a biotechnology technique, in which living microorganisms are used to degrade contaminants present in the soil and groundwater system. These microorganisms degrade toxic pollutants into less toxic compounds. Microorganisms used in bioremediation may be indigenous ones or may be genetically engineered for this purpose.
2. Bacteria derive energy required for growth and reproduction is obtained from degrading organic waste products. Bioremediation also uses same principle but in an altogether different setting. Using bioremediation technique speeds up the process of converting toxic compound into less toxic one by increasing the rate of bacterial metabolism and this also increases the bacterial growth.
3. Bioremediation is a cost effective technique because
a. Contamination are treated most of the times at the site, hence minimizes site disturbance.
c. In some of the incidence natural microorganisms can also be used for bioremediation purpose.
4. Biodegradation of toxic contaminants may not be very effective at the site, which contains high concentration of materials that are toxic to microorganisms. Materials such as metals, highly chlorinated organic compounds, inorganic salts.
5. Environment is also contaminated with heavy metals, and they can also be integrated into the food chain, hence will induce a huge health problem in humans. This heavy metal contamination can also be converted into disposable forms by using specific bacterial species. Some of the examples are
a. Uranium: This is a radioactive waste can contaminate water. This contaminant can be degraded by iron-eating bacteria.
b. Mercury: Research is going on in designing bacteria which can degrade this heavy metal.
Microorganisms Used in Bioremediation:
Many numbers of microorganisms can be used in bioremediation, because many of them use toxic chemical compound as their source of energy. Microorganisms like bacteria, fungi and also yeast are used in bioremediation.
Some of the examples of bacterial species used in bioremediation process include Pseudomas, Arthobacter, Alcaligenes, Corynbacterium, Flavobacterium, Achrombacter, Micrococcus, Nocardia, Mycobacterium and much more.
Using bacteria for bioremediation have got some of the beneficial characteristics such as,
a. bacteria consume organic wastes
b. bacterial cells rapidly grow and reproduce
c. Bacteria quickly and completely digest the complex wastes
d. Bacteria digest toxic material without causing any poisonous compounds or gases.
e. Bacteria used in bioremediation are non pathogenic or in other words they does not have have the ability to cause diseases in humans or animals.
Classes of Bioremediation:
1. Aerobic bioremediation: Microorganisms used for degradation of some toxic compounds, do so by using atmospheric oxygen.
2. Anaerobic bioremediation: Microorganisms used for degradation of some toxic compounds, do so by breaking down chemical compounds to release energy required for function.
Bioremediation Technology Selection:
1. The bioremediation technology suitable for a site of contamination can be determined by considering microorganisms present, condition of the site of contamination and quantity and level of toxicity of contaminants.
2. Bioremediation technology application can be divided into two main categories such as in situ and exsitu.
a. In situ: If contamination is occurred in water system or soil, bioremediation is done at the site. This is called as in situ bioremediation and is also cost effective. Some of the examples for in situ bioremediation are bio-venting, air sparging method.
b. Ex situ: Bioremediation is done not on the site of contamination. Contaminated soil or ground water is first excavated from its original site before treatment. Example for this type of bioremediation is slurry phase.
Uses Of Bioremediation:
1. Bioremediation method can be used to degrade crude oil spills, sewage effluent, chlorinated and non-chlorinated solvent used in the industries.
2. Bioremediation can also be used to degrade or decompose coal products such as phenols and also cyanides.
3. Bioremediation can also be used to degrade or decompose agricultural chemicals and pesticides
4. Bioremediation can also be used to degrade or decompose fuel oil contamination
5. Bioremediation can also be used to degrade or decompose wood preservatives.
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