What is Bioremediation?

Ingrid Yanet Sanchez Torres, Angela Hartsock
  • Author
    Ingrid Yanet Sanchez Torres

    Ingrid is an engineer in Renewable Energies from Mexico. She is currently studying his doctorate and has a masters degree in this area. She has taught for over 3 years topics like Math, Calculus, Statistics, Algebra, Physics and Biology in elementary school, high school and university.

  • Instructor
    Angela Hartsock

    Angela has taught college microbiology and anatomy & physiology, has a doctoral degree in microbiology, and has worked as a post-doctoral research scholar for Pittsburgh’s National Energy Technology Laboratory.

Explore bioremediation. Learn the definition of bioremediation and understand how it works. Discover the different advantages of bioremediation with examples. Updated: 02/02/2022

What is Bioremediation?

Human activities alter the natural balance of the environment, contaminating water and soil with substances that endanger its integrity. However, in many cases, the damage caused can be reversed or mitigated. This is where biology and the use of technology come into play, applying bioremediation techniques. But, what is bioremediation? Bioremediation is the use of microorganisms to remove or neutralize hazardous substances from contaminated water and soil. The microorganisms used include bacteria and fungi, which naturally live in the environment. Bioremediation stimulates the growth of certain microorganisms that use pollutants as a food and energy source. Some contaminants that are treated with bioremediation are oil and some derivatives, solvents, and pesticides.

The importance of bioremediation lies in the fact that the application of these techniques allows reducing or removing potentially hazardous waste that is in the environment. Therefore it is possible to reuse the land or water that once was contaminated.

Bioremediation helps eliminating contaminants from environmental disasters like oil spills.

Bioremediation of an oil spill on a rocky shore

How does Bioremediation work?

Most microorganisms are able to break down traditional contaminant substances like sugars, nutrients, proteins, and fats. These substances usually do not have complex molecules, so they are easy to degrade. But other microorganisms are able to degrade more complex substances like hydrocarbons, pesticides, TNT (dynamite), uranium, and heavy metals. Microorganisms that degrade these substances are found in a wide range of environments, These microorganisms absorb and digest these contaminants and they usually convert them into small amounts of water and harmless gases such as carbon dioxide and methane. If the soil and water sources do not have the microorganisms needed in sufficient quantity, they can be added through a process called bioaugmentation. Bioaugmentation is understood as the introduction of species of microorganisms that help the biodegradation of contaminants present in the soil or water.

To be effective, bioremediation requires a specific temperature, nutrients, and food. These conditions allow the indicated microorganisms to grow, multiply and absorb more pollutants. Without adequate conditions, the microorganisms grow too slowly or die and do not clean up contaminants.

Microorganisms can take months, or years, to bioremediate a polluted site. The total elapsed time depends on various factors like the concentration of the contaminant substances, the total surface extension, temperature, nutrients, the microbial population present in the site, or if the bioremediation had to be ex-situ. These microorganisms usually die after this process is finished since the contaminant that is a food source for them is eliminated. To guarantee that bioremediation is taking place, soil and water samples are taken periodically to measure the progress achieved.

Bioremediation Defined

I think it's universal. All of us, at one time or another, have been told to go clean our rooms. Even though we likely balked at the command as if it was a huge inconvenience, in reality it's a pretty simple task. Your room is pretty much self-contained with a general organization and a manageable (in most cases!) amount of stuff to be dealt with.

But what happens when there is a big mess in the environment? Something like an oil spill, or a chemical spill, or radioactive waste? How does that get cleaned up? And, maybe more importantly, who does the cleaning?

Bioremediation is a process where biological organisms are used to remove or neutralize an environmental contaminant or waste. The 'bio-' part refers to the biological organisms, which typically includes microscopic organisms, like fungi and bacteria. And, the '-remediation' part refers to remedying the situation.

Within the Earth's biosphere, microorganisms grow in the widest range of habitats. They grow in soil, water, plants, animals, deep sea vents, and arctic ice, just to name a handful. Their shear numbers (billions in a gram of soil, millions in a milliliter of water) and their appetite for a wide range of chemicals makes microorganisms the perfect candidate for acting as our environmental janitors.

Samples are taken from contaminated areas to evaluate the bioremediation process.

Samples being taken from contaminated areas to evaluate the bioremediation process.

Advantages of Bioremediation

The bioremediation process has multiple advantages. It has been widely used to solve cases of water and soil contamination around the world. Among its advantages:

  • This technique uses natural processes to clean contaminated sites, so no chemicals are added that could be harmful.
  • This method does not require large machinery, labor, or energy like other cleaning methods.
  • This process may have a lower cost than other cleaning methods.
  • Contaminated water and soil can be treated in the same place where the contamination occurred, without the need to move them to another place to be treated.
  • The by-products generated by microorganisms in removing contaminants are minimal or non-existent.
  • Contaminants are degraded to substances such as water or gases that are not toxic.

Bioremediation Examples

One of the most notorious cases of contamination of the seas was the explosion of the Deepwater Horizon oil platform in the Gulf of Mexico in 2010. In this disaster, more than 790,000 tons of oil were spilled and the damage caused extended from the US coast to Central America. To fix the damage, about 7 million liters of chemical dispersants were applied by injecting them into the area. Initially, the objective was to disperse the oil while it was still at depth so that the ships that were trying to contain the spill could do so more effectively and prevent the spill from reaching the coast. However, subsequent analysis of the oil cloud created by the dispersants showed that it had lower concentrations of O2(oxygen) and NO2 (nitrogen dioxide) and higher concentrations of NH3 (ammonia), indicating that the oil was undergoing bacterial activity. During analysis, it was seen that, indeed, the bacterial density was greater in the cloud. 951 bacterial subfamilies were found, of which 16 are thought to be related to the exclusive degradation of oil. In the end, these bacteria were responsible for helping to clean up the disaster and to limit the dispersion of this contaminant. This was an example that bioremediation can occur on a large scale.

Another example of bioremediation is the one that took place in Gujarat, India in 2008. In that place, a crude oil line broke, causing a spill. The pumping of crude oil was stopped and a company specialized in bioremediation was called. They decided to do an ex-situ bioremediation, so 14694 m3 of oil-contaminated soil were excavated and transported to bioremediation tanks. The polluted soil was mixed with agricultural fertile soil, and a crude oil degrading bacterial consortium was applied. After 4 months, the percentage of oil in the soil was 0.58%. The bioremediation soil was further used for green belt development (construction of parks and open areas).

Natural vs Artificial Environments in Bioremediation

When a site is contaminated, bioremediation can occur naturally by the microorganisms that are present in the environment. As mentioned in the previous sections, for this to happen the right conditions have to be given and there has to be an adequate population of microorganisms. These conditions can be improved by adding additives. Additives can be household items, such as molasses and vegetable oil, fertilizers, or air and chemicals that produce oxygen. Additives are usually added to the contaminated area to treat the soil and water in situ (in place). However, necessary conditions to bioremediate cannot always be achieved. In some places, the weather may be too cold for microorganisms to be active or the soil may be too dense to allow additives to disperse evenly uniform throughout the subsoil.

Microbial Diets are Diverse

Microbes can metabolize a wide range of chemical compounds. In this context, we are focusing on environmental pollutants but don't forget that microbes also break down the normal stuff, like sugars, proteins, and fats -- the stuff we typically think of as food. Some of the more exotic fare favored by microbes includes hydrocarbons (petroleum), pesticides, TNT (dynamite), and uranium.

In some cases, microbes can break down pollutants to completely harmless by-products, like carbon dioxide and water. In other cases, microbes can change the structure of the contaminant to make it harmless to humans and animals or change the solubility of the contaminant so that it can no longer mix into and move with water, effectively sequestering the contaminant and limiting human and animal exposure.

One example of bioremediation is the Deep Horizon oil spill in 2010. Incredible amounts of oil were spilled into the Gulf of Mexico. While humans mobilized massive containment and cleanup efforts, at a microscopic scale, a much more important cleanup was underway.

During and after the spill, scientists were tracking the oil contamination and taking samples to detect the activity and abundance of bacteria in the contaminated zone. Their analysis revealed a robust microbial response to the presence of the oil. Microbes, which were able to metabolize the oil, flourished and contributed significantly to the remediation of the contaminated zone. The microbial response was key to limiting the environmental impact of the spill.

The microorganisms (shiny bright objects) present in the water of the Gulf of Mexico.
Bacteria in water sample

Natural and Artificial Ecosystems in Bioremediation

So if microbes are so good at degrading our environmental contaminants what do we have to be worried about? By comparison to the idea of cleaning our rooms, when we think about clean up of a contaminant in the environment, we can envision some obstacles.

A mess in the environment isn't nicely contained like a mess in a room. Environmental contamination can spread through soil, water, and wind. Living organisms can come into contact with or consume the contaminant. And, even though many contaminants can be degraded by microbes, sometimes this microbial breakdown is really, really slow. Too slow for our comfort and safety.

So right now there are a few options when it comes to bioremediation:

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Additional Info

Bioremediation Defined

I think it's universal. All of us, at one time or another, have been told to go clean our rooms. Even though we likely balked at the command as if it was a huge inconvenience, in reality it's a pretty simple task. Your room is pretty much self-contained with a general organization and a manageable (in most cases!) amount of stuff to be dealt with.

But what happens when there is a big mess in the environment? Something like an oil spill, or a chemical spill, or radioactive waste? How does that get cleaned up? And, maybe more importantly, who does the cleaning?

Bioremediation is a process where biological organisms are used to remove or neutralize an environmental contaminant or waste. The 'bio-' part refers to the biological organisms, which typically includes microscopic organisms, like fungi and bacteria. And, the '-remediation' part refers to remedying the situation.

Within the Earth's biosphere, microorganisms grow in the widest range of habitats. They grow in soil, water, plants, animals, deep sea vents, and arctic ice, just to name a handful. Their shear numbers (billions in a gram of soil, millions in a milliliter of water) and their appetite for a wide range of chemicals makes microorganisms the perfect candidate for acting as our environmental janitors.

Microbial Diets are Diverse

Microbes can metabolize a wide range of chemical compounds. In this context, we are focusing on environmental pollutants but don't forget that microbes also break down the normal stuff, like sugars, proteins, and fats -- the stuff we typically think of as food. Some of the more exotic fare favored by microbes includes hydrocarbons (petroleum), pesticides, TNT (dynamite), and uranium.

In some cases, microbes can break down pollutants to completely harmless by-products, like carbon dioxide and water. In other cases, microbes can change the structure of the contaminant to make it harmless to humans and animals or change the solubility of the contaminant so that it can no longer mix into and move with water, effectively sequestering the contaminant and limiting human and animal exposure.

One example of bioremediation is the Deep Horizon oil spill in 2010. Incredible amounts of oil were spilled into the Gulf of Mexico. While humans mobilized massive containment and cleanup efforts, at a microscopic scale, a much more important cleanup was underway.

During and after the spill, scientists were tracking the oil contamination and taking samples to detect the activity and abundance of bacteria in the contaminated zone. Their analysis revealed a robust microbial response to the presence of the oil. Microbes, which were able to metabolize the oil, flourished and contributed significantly to the remediation of the contaminated zone. The microbial response was key to limiting the environmental impact of the spill.

The microorganisms (shiny bright objects) present in the water of the Gulf of Mexico.
Bacteria in water sample

Natural and Artificial Ecosystems in Bioremediation

So if microbes are so good at degrading our environmental contaminants what do we have to be worried about? By comparison to the idea of cleaning our rooms, when we think about clean up of a contaminant in the environment, we can envision some obstacles.

A mess in the environment isn't nicely contained like a mess in a room. Environmental contamination can spread through soil, water, and wind. Living organisms can come into contact with or consume the contaminant. And, even though many contaminants can be degraded by microbes, sometimes this microbial breakdown is really, really slow. Too slow for our comfort and safety.

So right now there are a few options when it comes to bioremediation:

To unlock this lesson you must be a Study.com Member.
Create your account

Frequently Asked Questions

What is an example of bioremediation?

Bioremediation is used to treat the soil and water in contaminated areas. An example of bioremediation on a large scale is the one that took place after the Deepwater Horizon oil spill in 2010. There, microorganisms helped to contain and remove the oil in the Gulf of Mexico.

What is bioremediation and why is it important?

Bioremediation is a biological technique to remove or neutralize hazardous substances from contaminated soil or water. Microorganisms like bacteria and fungi use these contaminants as sources of food or energy and transform them into water or harmless gases like carbon dioxide or methane. It is important because it contains the expansion of these substances and the treated soil and water can be reused.

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