Bioremediation has three different methods. These three methods differ in to what they utilize to clean the contaminated site. Generally, the type used depends on the characteristics of the area, such as the location of the site or the amount of contamination.
Bioremediation has three different methods. These three methods differ in to what they utilize to clean the contaminated site. Generally, the type used depends on the characteristics of the area, such as the location of the site or the amount of contamination.
The image shown to the the left shows a cleanup crew working on site, after the oil spill in the Gulf of Mexico.
MYCOREMEDIATION
Complex strategies
Polluted environments often contain many different sorts of toxic substances. Plants, mushrooms, and microorganisms can be combined in many different ways to regenerate healthy, thriving life in our soils and water. (4.4)
Bacterial Bioremediation
The bacteria involved in the process of bioremediation are simply gluttonous microbes. These naturally occurring microbes are placed within the contaminated site in which they immediately begin to start breaking down the organic contaminant. This "breaking down" process consists of these microbes breaking the carbon chains of which make up all organic molecules. The microbes thus work on breaking down the carbon chains until the contaminant is eliminated and no longer an environmental threat. As a result of this process carbon dioxide and water are left behind as by-products with trace elements of fatty acids. (4.5)
Delhi, who attended graduate school at U.C. Berkeley and is now the Assistant Professor of Civil and Environmental Engineering at UCLA. These days her science experiments focus on bacteria that clean up pollution. Through bioremediation, bacteria and fungi detoxify groundwater and soil contaminated with pollutants. (4.8)
Mycoremediation
The term "mushroom" refers only to the fruiting body, the visible reproductive organism of a larger body of mycellium. Mycellium are an underground web of threads or hyphae that are the main body of the organism.
Mushroom mycelium release enzymes that can break the chemical bonds of many petrochemicals and toxins. Some mushrooms can also take in heavy metals—they must then be harvested and treated as toxic waste. Different species work best for specific toxins.
A substrate, often wood chips, sterilized straw or cardboard, is inoculated with mushroom spawn of a beneficial species. This inoculated substrate can also be used as a filter for flowing water. Some species of fungi will attack pathogens and bacteria.
Mycorrhizal fungi live in association with plant roots. Their threads interpenetrate the roots, helping them take in more nutrients and water. They can improve soil and plant health, and protect against toxicity and disease. (4.4)
Navigate to the bottom to learn where mycoremediation was also used.
Bioremediation consists of different methods, and can be defined as the use of organisms to break down harmful environmental contaminants to restore the environment to a healthier state. Bioremediation utilizing fungi is called mycoremediation. Bioremediation using plants is called phytoremediation. The process using bacteria is called bacterial bioremediation. (4.2) (4.4)
Phytoremediation
Phytoremediation uses plants that can take up toxic substances (i.e. heavy metals). Specific plants absorb different substances. When harvested, plant materials need to be treated as toxic wastes and cannot be eaten. Some plants also generate an environment around their roots that favors the reproduction of beneficial bacteria that can break down toxins that are present. Because it is a natural process, phytoremediation can be an effective remediation method at a variety of sites and on numerous contaminants. Sites with low concentrations of contaminants over large cleanup areas, or in areas of shallow depth present especially favorable conditions for phytoremediation. (4.2) (4.3) (4.4)
Navigate to the bottom to learn where phytoremediation was also used.
The following videos show experts talking about the research being conducted and how different methods of bioremediation are currently used at contaminated sites.
Outside the small Virginia town of Crozet, the EPA is using phytoremediation to remove arsenic contamination from a residential property. Phytoremediation uses specially selected plants to remove or reduce the risk of contaminants in the soil, water, sediments, and air. (4.6)
Railroads
Trees spur bacterial growth by adding nutrients to the soil, and they have the added advantage of roots that extend up to 50 feet underground, allowing them to clean sites where contamination has penetrated deep into soil and groundwater. Traditionally, to clean these sites, companies have had to resort to extremely expensive and labor-intensive techniques, such as excavating entire areas and incinerating contaminated soil. In order to clean up creosote used for treating railroad ties at the former Union Pacific railroad facility in Laramie, Wyo., work crews had to dig up 20 feet of dirt. The company then tried to flush the chemical out of the soil with biodegradable soap.When that failed to remove residual creosote, Union Pacific planted cottonwoods, poplars, aspens and blue spruce. While the trees and the bacteria clean the contaminants, the site has become a city park. Similar techniques are being used at other railroad sites (4.13)
Below are examples of how phytoremediation was used to clean contaminated sites.
Metals
Hyper accumulators are the plants that can actually transport and accumulate extremely high levels of soil pollutants within their bodies. Hyper accumulators are already being used throughout the country to help clean up heavy metals and polluted soil. Heavy metals are some of the most stubborn soil pollutants. They can bond very tightly to soil particles, and they cannot be broken down by microbial processes. Most heavy metals are also essential plant nutrients, so plants have the ability to take up the metals and transport them throughout their bodies. However, the levels of heavy metals are often hundreds of times greater than normal, and this overexposure is toxic to the vast majority of plants. Hyper-accumulators, on the other hand, actually prefer these high concentrations. Essentially, hyper-accumulators are acting as natural vacuum cleaners, sucking pollutants out of the soil and depositing them in their above ground leaves and shoots. Removing the metals is as simple as pruning or cutting the hyper-accumulators above ground, as opposed to mass excavation of the soil. (4.14)
Toxic Waste
Radiation-loving mushrooms, scientifically referred to as “radiotrophic fungi,” have many potential applications. In 1987, at the Chernobyl toxic waste site, highly contaminated graphite used to cool the reactor was observed being decomposed by a yet unknown species of fungi. After the Chernobyl meltdown, mushroom hunters all over Europe were advised not to pick and eat certain species of fungi because they could be concentrating radioactive fallout. Gomphidius glutinosus is a common woodland mushroom that concentrates radioactive cesium-137 to over 10,000 times normal levels. An area that has been contaminated with deadly cesium, like the area surrounding the Fukushima nuclear power plant in Japan, could have spores from this species of fungi spread on it, and then later when the radioactive mushroom caps appeared, they could be collected and properly disposed of. (4.15)
Below are other examples of how mycoremediation was used to clean contaminated sites.
TNT
These fungi have enzymes to break down lignin, which is a tough material in wood. They tear down the lignin in order to get to their food supply, but as it turns out, their enzymes are highly nonspecific. They can break down organic toxins, leaving other harmless compounds that other microorganisms use as food. Bennett's first bioremediation project with scientists Connick and Daigle involved Phanerochaete chrysosporium, commonly known as the white rot fungus. Bennett wants to use the fungus’ might against residues left from munitions production. The Cold War’s end brought closure for many weapons factories, but toxic souvenirs such as TNT (trinitrotoluene) remain. Research shows that TNT can cause liver damage and anemia. TNT poisons a host of other life forms, including fish, algae—and some kinds of fungi. But if P. chrysosporium proves to be effective, it might help turn back the clock for these former weapon-production sites. (4.16)
Soil & Water
Fungi seems to be hated by everyone, but they can actually be quite useful. German researchers are developing new ways of using fungus to clean soil and water.
Fungi have earned their reputation as a homeowner's nightmare. Once they've settled into wood and been exposed to moisture, all that's left are brittle remains that turn into dust at the slightest touch.
Fungi get their destructive abilities from enzymes that break down lignin, a complex chemical compound that is largely responsible for holding wood together. Enzymes in fungi, including the so-called laccase enzyme, are among the few compounds capable of decomposing lignin. Tapping into the power of these enzymes, German scientists are finding new ways to use fungi to break down toxins, including at sewage treatment plants. (4.17)