Uses of Biotechnology in Environment

Bioremediation

It refers to the cleaning of environment with the help of living organisms. Living organisms range from microorganisms to different species of plants. For example, bacteria help in the decomposition of organic waste and certain plant species such as mustard helps in the absorption of poisonous elements such as selenium.

Bioremediation usually takes a longer time period. However, bioremediation effectively discriminates between pollutants and the required nutrients.

Strategies of bioremediation are mentioned below:

In situ bioremediation techniques It refers to the treatment of waste at its site. These techniques not only assist in the degradation of adsorbed fuel residuals, but also assist in the degradation of volatile organic compounds. In situ bioremediation techniques include biosparging, bioventing, bioaugmentation and bioculture.

1. Biosparging: It is an in situ remediation technology that uses indigenous microorganisms to biodegrade organic constituents in the saturated zone. In biosparging, air (or oxygen) and nutrients are injected at high pressure to increase the biological activity of the indigenous microorganisms and to enhance their decomposition activity.

2. Bioventing: It is an in situ remediation technology that uses microorganisms to biodegrade organic constituents adsorbed in soils in the unsaturated zone. Bioventing enhances the activity of indigenous bacteria and simulates the natural in situ biodegradation of hydrocarbons in the soil by inducing air or oxygen flow at low pressure into the unsaturated zone and, if necessary, by adding nutrients. In conventional bioventing systems, oxygen is delivered by an electric blower to subsurface wells.

3. Bioaugmentation: In this technology, the microorganisms are imported to the contaminated site to carry out degradation of organic waste. For instance, oil zapper (explained earlier).

4. Bioculture: It is a bacterial formulation to improve waste degradation in septic tanks and eliminate odours due to organic buildup. Bioculture refers to the use of blend of bacteria that collectively produce enzymes for the degradation of fats, oils, proteins, starch and carbohydrates.

Ex Situ bioremediation techniques Ex situ refers to the transfer of contaminated material for treatment to some other site. Ex situ bioremediation techniques include land farming and biopile.

1. Land farming: In this technique, the contaminated soil is spread over a prepared bed. The soil is periodically tilled to stimulate the growth of microorganisms for degradation of organic waste.

2. Biopile: It is a hybrid of land farming and composting. Excavated soils are spread over a prepared bed, formed into compost piles and enclosed for treatment.

Moisture, heat, nutrients, oxygen, and pH are controlled to enhance biodegradation. An irrigation/ nutrient system is used to pass air and nutrients through the soil. Soil piles can be up to the height of 20 feet. They may be covered with plastic to control runoff, evaporation and to promote solar heating.

Treatment time is typically three to six months, after which the excavated material is either returned to its original location or disposed off.

The treatment area is generally covered or contained with an impermeable lining to minimise the risk of contaminants leaching into the uncontaminated soil.

Bioremediation Techniques

1. Phytoremediation: It means the use of plants to remove contaminants from soil and water. Neem plant is used for phytoremediation as it absorbs poisonous elements and reduces the growth of harmful microorganisms.

2. Phytoextraction: It is a subprocess of phytoremediation in which plants remove dangerous elements or compounds from soil or water, mostly heavy metals, metals that have a high density and are toxic to organisms even at relatively low concentrations.

3. Mycoremediation: It involves the use of fungus such as mycelia to decontaminate an area. Mycorrhiza is another type of fungus which is used for bioremediation. It also has other important uses in agriculture.

‘Mycor’–’rhiza’ literally means ‘fungus’–’root’. It exists in mutually beneficial relationship with plant roots. These fungi develop on plant roots and extend far into the soil. Thereafter, these fungi act as extensions of root systems and are in fact more effective in nutrient and water absorption than the roots themselves. Mycorrhiza also protects plants against pathogens and toxic substances present in the soil. The fungus also facilitates restoration and helps in revegetation of disturbed mined lands.

Drawbacks Of Biotechnology

1. Biotechnology can be used to develop Weapons of Mass Destruction (WMD). Biological weapons of mass destruction are cheap and easy to build. Moreover, these weapons have devastating effect only on living organisms and does not affect infrastructure.

2. Biotechnology can bring back certain extinct forms of life which may lead to some unpredictable and harmful consequences. For instance, Smallpox virus can be regenerated and left in the environment to infect people.

3. Biotechnology may have a negative effect on biodiversity. At present, few plant and animal species are focus of research leading to ignorance of other species. The focus on few species may lead to their growth and can have a negative effect (even extinction) on remaining species.

4. Biotechnology is used to develop plant varieties with terminator genes. A terminator gene in a genetically modified crop plant stops the plant from releasing fertile seed. Hence, the farmer is again required to purchase the seeds in the next cropping season. The practice of incorporating terminator gene trait in some seed varieties is adopted by multinational companies (MNCs) to enhance their sale of seeds. This terminator trait may cross-pollinate with local varieties and may affect the continuity of agriculture.