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In Situ Bioremediation: Definition & Techniques

Instructor: Angela Hartsock

Angela has taught college Microbiology and has a doctoral degree in Microbiology.

In this lesson we will take a look at how biological organisms can break down environmental pollutants in a process called bioremediation. We will consider a special case of bioremediation, called in-situ bioremediation, where contaminated soil or water is cleaned up without removing it from its natural setting.

Bioremediation

Let's face it, our fancy lives make a bunch of definitely not fancy messes. Oil spills, fertilizer and pesticide runoff, industrial waste, and chemical disposal all represent the less glamorous side of our society and its impact on the environment. Sometimes we do our best to limit or clean up our own messes, but we also get a lot of help from some under-appreciated friends.

Bioremediation happens when biological organisms like bacteria, fungi, and plants break down or neutralize environmental contaminants. But, let's get one thing straight. The organisms doing the bioremediation sure as heck aren't doing it for us (to make us less guilty or keep us safe). Nope, they are going after these chemicals because they can use them for energy and metabolism.

In-situ Versus Ex-situ Bioremediation

Iif bioremediation just refers to the general process where biological organisms help with contaminant clean up then the qualifiers in-situ and ex-situ tell us something about where the bioremediation is taking place. In-situ really just means in place or on site (keeping something in its natural place), and ex-situ just means out of place or off site (removing something from its natural place).

In-situ bioremediation means that you allow bioremediation to take place while leaving the soil or water in its natural location. And, ex-situ bioremediation means you would scoop up the contaminated soil or pump up the contaminated water and take it somewhere else for bioremediation. Let's think a little bit more about the in-situ process.

Boosting In-situ Bioremediation

Just because in-situ bioremediation leaves things in their natural place, that doesn't mean we can't step in and help the process along. If everything is going great, then fine, we can let bioremediation proceed without intervention, a process called natural attenuation.

Otherwise, there are a couple common options for how to boost bioremediation. In some instances, the biological organisms attacking the contaminants are kind of slow, sometimes because they lack a key nutrient for their growth and metabolism. In that case, simply providing that needed nutrient can significantly boost the rate of bioremediation. This is called biostimulation.

In other cases, even boosting the naturally occurring organisms isn't enough to get the job done. In that case, if scientists know of an organism (or organisms) that can rapidly attack the contaminant, then that organism can be added directly to the environment to aid in bioremediation. That process is called bioaugmentation.

This image shows the injection of nutrients (biostimulation) to promote in-situ bioremediation of a contaminated groundwater aquifer.
Biostimulation well

Challenges Associated with In-situ Bioremediation

It seems like in-situ bioremediation is just an awesome way to get contaminants cleaned up. But, the environment is chaotic, conditions change constantly, and in some conditions or environments in-situ bioremediation can be a challenge.

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