Bioremediation is a form of environmental cleanup which relies on biological organisms such as plants, fungi, and microorganisms like bacteria. Humans have been employing this technique for centuries, and in the late 20th century, it began to be applied more widely to an assortment of environmental problems all over the world. An example of ancient bioremediation is the use of plants to pull salts out of the soil to make it arable again, while a classic instance of modern bioremediation involved the use of beneficial bacteria to help clean up the Exxon-Valdez oil spill in Alaska.
People often use the term “phytoremediation” to talk about bioremediation with plants, and “mycoremediation” to discuss situations in which fungi are used, reserving “bioremediation” to refer to the use of microorganisms such as bacteria, protozoans, and so forth. In all cases, the goal is to harness natural traits of the organism to deal with an environmental issue, or to genetically engineer an organism which can cope with an environmental situation.
Many bacteria break down toxins as part of their normal metabolic processes, rendering harmful substances inert. This trait is often used in situations where toxins have been released into large areas, making these areas essentially impossible to clean or contain. Contaminated rivers, for example, can be cleaned out with carefully introduced bacteria. The bacteria will die off once the supply of toxins is exhausted, because they will run out food supplies, thereby preventing the development of a secondary environmental problem.
Environmental agencies can use living organisms on site with in situ bioremediation, in which the desired organisms are carefully introduced to the environment and their progress is tracked until the site has been cleaned up, or they can use them off site. Ex situ bioremediation is used to clean contaminated soils and other materials which have been removed and isolated so that they can be rendered inert and safe to handle. This technique reduces the buildup of toxins and hazards in landfills and isolation facilities, which leaves the Earth cleaner for future generations.
One of the big advantages to bioremediation is that it cleans up a problem without creating a problem. The process can be used to treat new and old toxins, which makes it useful in containment of emerging problems as well as environmental remediation which is designed to address old issues, like factory pollution dating back decades. The organisms used are often self-contained, dying out once the task has been accomplished, and in the case of genetically engineered organisms, researchers can specifically design the organisms so that they will be easy to eliminate from the environment once they have served their purpose.