In simple terms, the word itself can be aliquoted into ‘bio‘ + ‘remedy‘, which implies applying remedial measures to systems pertaining to biology. A biological system can act as a natural attenuator when it comes to cleaning up contaminants present in an environmental patch. Sometimes, it develops naturally owing to surface topology while at other times it is man-triggered.
Contamination may be of a large ecosystem , a smaller one or a micro-scale proliferation of pollutants. This has direct adverse effect on one form of living organism or another. E.g. eutrophication will prevent fishes and frogs to live in a lake ; brick walls may possess unwanted growth of weeds and algae which will weaken it ; a very arable land loses its fertility owing to an oil spill and many more.
Sometimes it is easy to remove a contaminant using chemicals, but it is highly specific and may be slow. It may even produce a by-product at the end of treatment which may still be difficult to decompose. One advantage of Bioremediation techniques is that they are proven remedies by nature and non-decomposable end product is a rare occurrence.
Plant Bioremediation :
Generally Bioremediation in plants is applied either via direct intrinsic contact with a plant or a plant part(Phytoremediation) or by creating a sphere of influence near the roots called rhizosphere (Rhizoremediation). The latter is more useful as it can be easily monitored and damages to plants can be reverted.
Microbial Bioremediation :
Not only plants possessing unique cleansing properties are useful but also certain ‘good’ microorganisms that help in soil / water / air decontamination. Owing to evolution, bacteria and archaea have evolved techniques to use the ‘natural’ crude oil as energy source. This technique may be very slow, but almost 100% effective.
Animal Bioremediation :
At some other times, even animals (insects etc.) that form part of the food chain can also play a major role. They are Decomposer animals that interact effectively with soil bacteria and fungi which may directly or indirectly become their feed.