6 Ecology and Environmental Biology

6.6 Bioremediation

Bioremediation

Dr V Malathi

Bioremediation is a branch of biotechnology that employs the use of living organisms, like microbes and bacteria, in the removal of contaminants, pollutants, and toxins from soil, water, and other environments. Microorganisms destroy organic contaminants in the course of using the chemical pollutants for their own growth and reproduction.
Bioremediation is the most effective, economical, eco-friendly management tool to manage the polluted environment.

How Bioremediation Works ?

Bioremediation relies on the metabolic processes of microorganisms that “digest” contaminants. These microorganisms can use pollutants as a their source of energy or nutrients and in the process break down complex pollutants molecules into simpler, harmless substances.  The effectiveness of bioremediation depend on factors like temperature, pH, oxygen levels, and nutrient availability, as these conditions affect microbial activity.

Types of Bioremediation

  1. In Situ Bioremediation / On site treatment for detoxification : Treatment occurs directly at the site of contamination, making it less disruptive and cost-effective.

In-situ bioremediation is of two types; these are intrinsic and engineered bioremediation

Intrinsic bioremediation
Intrinsic bioremediation also known as natural reduction.It  is an in-situ bioremediation technique, which involves passive remediation of polluted sites, without any external force (human intervention). This process deals with stimulation of indigenous or naturally occurring microbial population. The process based on both microbial aerobic and anaerobic processes to biodegrade polluting constituents. This technique is less expensive compared to other in-situ techniques.
File:In Situ Bioremediation.png
“In -situ Bioremediation” by Hoodlind via CreativeCommons.org, via Wikimedia Commons is licensed under CC BY-SA 4.0
Engineered in-situ bioremediation

Genetically Engineered microorganisms used in the in-situ bioremediation accelerate the degradation process by enhancing the physicochemical conditions to encourage the growth of microorganisms.

    • Bioventing: Adds oxygen to contaminated soil to enhance the growth of aerobic (oxygen-using) bacteria that can break down pollutants.
    • Biosparging: Injects air into groundwater to stimulate microbial activity, which helps degrade pollutants in underground water sources.
    • Phytoremediation: Uses plants to absorb and sometimes metabolize contaminants in soil or water.

File:Phytoremediation Process.svg

“Phyto remediation process” by Townie (Arulnangai & Xavier Dengra from the original in .png extension) is licensed under CC BY-SA 4.0

  1. Ex Situ Bioremediation/Of site treatment toxic materials
     Contaminated materials are removed from their original location and treated elsewhere, allowing for better control of conditions. Techniques include:

    • Landfarming: In this type the contaminated soil is spread over a large area and periodically tilled. This allows microbes to break down contaminants with the help of oxygen and sunlight.
    • Composting: This involves mixing of organic pollutants  with composting materials to foster microbial growth and thereby accelerates decomposition of the pollutants.
    • Bioreactors:  The contaminated water or soil is placed in a controlled tank  called bioreactor,where microbes are introduced to break down pollutants in optimal conditions.

Applications of Bioremediation

Bioremediation is applied in various scenarios where pollutants are present, including:

  • Oil Spill Cleanup: Some bacteria have the ability to degrade hydrocarbons in oil spills, which aids in clearing contaminated shorelines and water.
  • Heavy Metal Removal: To help remediate soil and water, certain microbes have the ability to sequester or change heavy metals like lead, mercury, and cadmium into less harmful forms.
  • Industrial Waste Treatment:By breaking down complex organic contaminants, bioremediation aids in the treatment of hazardous waste from industries like chemical manufacture.
  • Agricultural Pollution: By lowering pesticide and herbicide residues in soils, bioremediation can help make agricultural land safe to use again.

File:Biodegradation of Pollutants.png

“Biodegradation of pollutants” by Timmer26 Via Timmer26, creativecommons.org, via Wikimedia Commons is licensed under CC BY-SA 4.0

Advantages of Bioremediation

  • Environmentally Friendly: Because it is a natural process and does not involve harsh chemicals, ecosystems are frequently less disturbed.
  • Cost-Effective: Bioremediation can be less expensive than other cleanup techniques, especially for large-scale contamination sites.
  • Minimal Waste Production: Bioremediation frequently results in less trash because it breaks down toxins instead of physically removing them.
  • Versatile:It can be used on a variety of contaminants, including heavy metals and organic compounds.

Limitations of Bioremediation

  • Dependence on Environmental Conditions:Bioremediation requires a number of environmental conditions to function, such as adequate oxygen and nutrients, which can be difficult to control on-site.
  • Time-Consuming: Cleaning up areas may take longer time than with some chemical or physical repair methods.
  • Limited by Pollutant Type: Certain pollutants might be too dangerous for most microbes or have a high resistance to microbial degradation.

Watch the video on

Bioremediation: Restoring Contaminated Ecosystems, Naturally (Short) from THE ROYAL SOCIETY OF VICTORIA

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6.6 Bioremediation by Dr V Malathi is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License, except where otherwise noted.

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