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Key Difference – In Situ vs Ex Situ Bioremediation

Bioremediation is a term used in biotechnology to refer the process of cleaning the polluted areas using biological organisms such as microorganisms and plants. The use of organisms to reduce and transform contaminants into non-toxic substances is an environmentally friendly process which does not negatively affect the environment and organisms. Bioremediation can be done mainly in two methods known as in situ and ex situ. The key difference between in situ and ex situ bioremediation lies on the place where the process is carried out. In in situ bioremediation, contaminants are degraded at the same site where it’s found while the contaminants are treated in a different place in ex situ bioremediation.

1. Overview and Key Difference
2. What is Bioremediation
3. What is In Situ Bioremediation
4. What is Ex Situ Bioremediation
5. Side by Side Comparison – In Situ and Ex Situ Bioremediation
6. Summary

What is Bioremediation?

Waste management is of utmost importance for the benefit of human health. There are different waste management techniques developed to clean the environment namely, thermal, chemical and physical methods. Among these, chemicals are in popular use due to its ease of use and immediate results. However, chemical methods are proven to be non-ecofriendly methods since they have negative impacts on land, soil and organisms. Therefore scientists were keen on finding alternative methods which were safe, environmental friendly and sustainable. Bioremediation is such a type of waste management technique which uses biological organisms to alleviate environmental pollution. Bioremediation can be defined as a process which removes or neutralises waste and toxic substances in the environment, using organisms such as microorganisms, small organisms and plants. Many microorganisms and plants are capable of degrading toxic and hazardous substances and reducing the toxicity. Naturally occurring microorganisms decompose the organic waste in the environment by biodegradation.

Bioremediation  can also be referred as an engineered technique applied by people to clean up organic matter by helping microbes with the biodegradation process. Bioremediation process depends on the organisms used, environmental factors and type, volume and the state of the contaminant, etc. Bioremediation is applied in many processes: industrial and domestic waste water treatment, solid waste treatment, drinking water treatment, soil and land treatment, etc. There are two main types of bioremediation; in situ and ex situ.

Difference Between In Situ and Ex Situ Bioremediation

Figure 01: Removing salt from soil by bioremediation

What is In Situ Bioremediation?

In situ bioremediation refers to the bioremediation process which is performed at the original site of the contamination. In situ bioremediation concept is mainly used to treat contaminations in soil and ground water. However, the remediation rate and the effectiveness of the process depend on different factors. They are as follows:

  1. The type of the contaminant concern
  2. Site-specific characteristics
  3. Contaminant distribution and concentration
  4. Concentration of other contaminants
  5. Microbial community of the site
  6. Temperature
  7. pH of the medium
  8. Moisture content
  9. Nutrient supply

The manipulation of above factors is not highly feasible in in situ bioremediation. However, in enhanced in situ bioremediation, some manipulations such as aeration, adding nutrients, controlling moisture content, etc. are used to enhance the activity of organisms and increase the rate of degradation. But in intrinsic in situ bioremediation, natural processes are allowed to happen without altering the conditions or adding amendments.

Examples of in situ bioremediation technologies include bio-venting, enhanced biodegradation, bioslurping, phytoremediation, natural attenuation, etc.

What is Ex Situ Bioremediation?

Ex situ bioremediation is a technique which treats the contaminants away from the location where they were found. Contaminants are excavated or pumped out from the original site and treated inside the controlled environments. A wide range of hydrocarbons is purified by ex situ bioremediation. Contaminated soils are excavated and placed on the surface of the ground and treated using indigenous microorganisms. Ex situ bioremediation can be controlled and managed by providing required conditions.

Examples of ex situ bioremediation processes including composting, soil biopiles, landfarming, slurry reactors.

What is the difference between In Situ and Ex Situ Bioremediation?

In Situ vs Ex Situ

In situ bioremediation process is performed at the original site of the contaminant. Ex situ bioremediation process is performed out of the location where the contaminant is found.
This process is less expensive This process is expensive.
This process is less thorough. This is a more thorough remediation method.
This process is less manageable. This process is manageable.
This process is less effective. This process is more effective.

Summary – In situ vs Ex situ Bioremediation

Bioremediation is the process which uses biological systems such as microorganisms and plants to reduce or destroy the concentrations of contaminants in the polluted environments. It can be done in two ways: in situ or ex situ. In in situ bioremediation, contaminants are treated at the same site using biological systems. In ex situ bioremediation, contaminants are treated in some other place from the original site. This is the key difference between in situ and ex situ bioremediation. Bioremediation processes are cost effective, safe and nature-based methods over the chemical and physical methods.

1.”Bioremediation.” Wikipedia. Wikimedia Foundation, 27 Feb. 2017. Web. 02 Mar. 2017
2.Adnan, Amna. “Types of Bioremediation | Role of Biotechnology in Bioremediation.” Types of Bioremediation | Role of Biotechnology in Bioremediation. N.p., n.d. Web. 02 Mar. 2017

Image Courtesy:
1. “Mechanism of salt removal from tsunami affected soil by bioremediation” By By M. Azizul Moqsud and K. Omine –  (CC BY-SA 3.0) via Commons Wikimedia