Bioremediation: Microorganisms Cleaning the Environment
Mycoremediation is one of the more modern forms of bioremediation. It is used to remove chemicals, such as diesel from the soil. Using fungi, it decomposes subtances. The fungi secrete enyzmes and acids. These enzymes and acids break down lignin and celluose, the two main components of plant fibers. These eventually break down the chemicals into carbon dioxide and water. In order for this process to work, a very specific fungi is needed for each purpose. (PR1)
Phytoremediation uses plants to control pollution. There are three main ways plants can be used to control pollution: phytoextraction, phytostabilization, and phytotransformation.
Phytoextraction removes salts makes the land more cultivable. Using a plant's natural ability, it absorbs toxic chemicals and heavy metals.
Phytostabilization engages the pollutant, but doesn't absorb it. It insteads stores the pollutant around the roots. This is useful to prevent the spreading and exposure of the toxins.
Phytotransformation is the final method. Also called phytodegradation, it decomposes the basis of the pollutants. This is from the result of the creation of an enzyme from the plant or through the metabolic processes that happens within the plant. (PR1) (PR2)
Bioremediation also includes the use of bacteria. This process is similar to mycoremediation as it needs specific bacteria. However, it is more easily contained. The bacteria simply consumes the contaminant and uses it for energy. With such use of specific bacteria, once the pollutant is cleared up, the bacteria either becomes dormant or dies. This prevents any complications from arising due to the use of this process. (PR1)
Examples of Phytoremediation
Metals
Phytoremediation is already being used around the nation to help clean up metal pollution in soil. Heavy metals are very persistent soil pollutants. Because their bonds with soil particles are very strong, they can't be destroyed by processes involving microorganisms. Many heavy metals are also nutrients for plants, so plants are able to take them in and carry them through the plants' bodies. However, the levels of heavy metals are much higher than normal in polluted soil. This exposure to high levels of metal is poisonous to many various plant families. Hyper-accumulators, plants that transport and accumulate high levels of soil pollutants in their bodies, actually prefer these high concentrations. These hyper-accumulators naturally suck pollutants from the soil and place them in their leaves and shoots. (PR3)
Railroads
Phytoremediation builds on already existing bioremediation technology. Traditionally, bioremediation uses bacteria to clean up environmental waste. Bacteria eat up carbon in the soil they live in. Carbon is in all organic compounds, including petroleum products. While the microbes eat at the carbon, they break the bonds of the compounds. The process of involving bacteria eating oils was used to clean up big spills, such as Alaska's Exxon Valdez spill. Plants could speed this process up even further. For example, trees increase the growth of bacteria by adding nutrients to the soil, and can use their long roots to clean sites deep underground. Generally, companies had to use extremely expensive and laborious methods, like incinerating contaminated soils. Work crews in a railroad facility in Laramie, Wyo., had to excavate dirt up to 20 feet to clean up the creosote that is used to sanitize railroad ties. Using biodegradable soap, the company tried to flush the chemical out. (PR4)
Examples of Mycoremediation
Soil and Water
Fungi are generally disliked by people. However, they can actually be very useful. Researchers are developing ways to use fungi to break down toxins. The scientists behind this are trying to use the laccase enzyme, which occurs naturally in fungi to break down lignin, to clean soil and water. Because laccases are not selective and instead attack a broad range of chemical structures, scientists are using the enzymes to attack the pollutants in the environment. Fungi and bacteria tremendously help the environment. Fungi extend long hyphae into the ground and bacteria can grow and travel on these hyphae for several meters. (PR5)
Toxic Waste
Scientifically referred as radiotropifc fungi, mushrooms have many uses to clean up contaminants. At the Chernobyl site in 1987, a toxic graphite was observed because of the decomposition of a yet unknown fungi species. Many species of these fungi are able to concentrate different metals. Mushroom hunters all over Europe were recommended not to eat certain types after the Chernobyl meltdown as they could contain radioactive fallout. A common woodland mushroom, Gomphidius glutinosus, concentrates radition cesium-137 to over 10,000 times. As the spores of the species spread and mushroom caps come about, they are picked and propertly disposed of. (PR6)
Examples of Bacterial Bioremediation
Oil Spills
Bacteria are useful to clean up and prevent oil spills. Bacteria eat at carbons in oil and degrade the levels of oil when spilled. A recent study shows that oil-degrading microbes have been rapidly eating away at the oil plumes on the Gulf of Mexico. Naturally occurring bacteria ate 200,000 tons of oil that spilled into the Gulf after the BP Deepwater Horizon spill. The bacteria removed most of the oil and gas that was trapped underwater. The study shows that naturally occurring oil-eating bacteria degrade oil plumes very rapidly. (PR9) (PR10)
Settling Ponds-It's Role and How it Helps Us
Settling ponds are ponds that collect water so that it calms down enough to allow solids to precipitate out of the water. These solids settle at the bottom of the pond and collect there. The water leaving the ponds will not have much of the metals or the toxins it had before. The solids that sink to the bottom at of the water is eventually cleaned out and must be occasionally. Settling ponds also have another function: exposing water to oxygen. Its large surface area allows the oxygen from the atmosphere to dissolve into the water. The oxygen reacts greatly with the ferrous iron to form ions, which becomes yellowboy and settle. (PR7)
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Groundwater
In-situ bioremediation is implemented in many different methods of treatment, such as, aerobic, anaerobic, and co-metabolic. The aerobic method has proven to be the most effective. Groundwater is oxygenated to reduce levels of contaminants. Three methods used to oxygenate groundwater are: Direct bubbling of air or oxygen through a well, saturating water with air or oxygen before being re-injected, or adding hydrogen peroxide into an injection well or into water that has been re-injected. (PR13)
Naturally occurring bacteria feed on toxic solvents in groundwater. A solution of cheese whey, emulsified vegetable oil and water was created to be injected into wells going down 30 to 40 feet. This solution will encourage the growth of the bacteria which will then cause the rapid decay of toxic solvents in groundwater. (PR11)
