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Biodegradation
BiodegradationBiodegradation is the decay or breakdown of materials that occurs when microorganisms use an organic substance as a source of carbon and energy. For example, sewage flows to the wastewater treatment plant where many of the organic compounds are broken down; some compounds are simply biotransformed (changed), others are completely mineralized . These biodegradation processes are essential to recycle wastes so that the elements in them can be used again. Recalcitrant materials, which are hard to break down, may enter the environment as contaminants. Biodegradation is a microbial process that occurs when all of the nutrients and physical conditions involved are suitable for growth. Temperature is an important variable; keeping a substance frozen can prevent biodegradation. Most biodegradation occurs at temperatures between 10 and 35°C. Water is essential for biodegradation. To prevent the biodegradation of cereal grains in storage, they must be kept dry. Foods such as bread or fruit will support the growth of mold if the moisture level is high enough. The microorganisms need energy plus carbon, nitrogen, oxygen, phosphorus, sulfur, calcium, magnesium, and several metals to grow and reproduce. The oxidation of organic substances to carbon dioxide and water is an exothermic (heat-releasing) process. For each mole of oxygen used as electron acceptor (oxidant), about 104 kilocalories (435 kJ) of energy is potentially available. All organisms make use of only part of this energy. The rest is lost as heat. This can be seen in composting when the compost becomes hot. Biodegradation can occur under aerobic conditions where oxygen is the electron acceptor and under anaerobic conditions where nitrate, sulfate, or another compound is the electron acceptor. Bacteria and fungi, including yeasts and molds, are the microorganisms responsible for biodegradation. Environmental managers want to use biodegradation when it is needed and prevent it when preservation is important. Chemicals are commonly used to treat wood in buildings and other structures to prevent biodegradation. Wooden posts and pilings are treated with creosote or copper compounds to prevent rotting. Compounds that inhibit biodegradation are often added to automobile antifreeze solutions, aircraft deicer formulations, and other products to preserve the original qualities of the product. These products and chemicals can enter the environment and become contaminants. The inhibitors have a negative effect when the product becomes a waste and is to be biodegraded. For example, biodegradation of aircraft deicer formulations in airport runoff is often inhibited because of the benzotriazoles that are present to preserve the formulation. see also Bioremediation; Solid Waste. BibliographyAlexander, Martin. (1994). Biodegradation and Bioremediation. New York: Academic Press. Gibson, David T., ed. (1984). Microbial Degradation of Organic Compounds. New York: Marcel Dekker. Internet ResourcesKansas State University. Great Plains/Rocky Mountain Hazardous Substance Research Center Web site. Available from http://www.engg.ksu.edu/HSRC. Larry Eugene Erickson and Lawrence C. Davis |
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Erickson, Larry Eugene; Davis, Lawrence C.. "Biodegradation." Pollution A to Z. 2004. Encyclopedia.com. 31 May. 2012 <http://www.encyclopedia.com>. Erickson, Larry Eugene; Davis, Lawrence C.. "Biodegradation." Pollution A to Z. 2004. Encyclopedia.com. (May 31, 2012). http://www.encyclopedia.com/doc/1G2-3408100029.html Erickson, Larry Eugene; Davis, Lawrence C.. "Biodegradation." Pollution A to Z. 2004. Retrieved May 31, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1G2-3408100029.html |
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biodegradation
biodegradation Biodegradation is the decomposition of organic compounds mediated by micro-organisms. This involves the oxidation of organic matter under both aerobic and anaerobic conditions by a variety of different micro-organisms. Bacteria and fungi are largely responsible for the breakdown of organic matter on Earth. They thus play a fundamental role in driving the biogeochemical cycles of elements at the Earth's surface. The degradation of natural organic compounds is very efficient; little survives to be buried in soils and sediments. In the absence of oxygen, biodegradation can be more restricted than in its presence, leading to greater preservation.
Biodegradation is harnessed in sewage treatment and in landfills to treat domestic and industrial waste. It can also be used to produce fuels, such as methane, from cheap or surplus agricultural crops. Conversely, the biodegradation of food and related products has to be prevented by killing micro-organisms (for example, by means of high temperatures during canning, or by irradiation), or slowing down their activity (for example, by freezing, refrigeration, drying, or preservatives). On a larger scale, biodegradation has to be prevented in the oil industry (in reservoirs, storage tanks, and pipes) and other industries, since bacterial activity can degrade the product and corrode and block pipes with biofilms. In these situations large quantities of biocides are used for bacterial control. Micro-organisms can also degrade a range of toxic xenobiotic compounds (synthetic chemicals, which do not occur naturally) such as herbicides and pesticides. Some xenobiotics are, however, resistant to biodegradation and thus can accumulate to toxic levels in the environment. Micro-organisms are not invincible, despite their diverse metabolism and ability for metabolic evolution. Related to biodegradation is biodeterioration, in which microbes do not significantly degrade a compound or matrix, but cause more subtle changes which results in its devalua-tion (e.g. odours in food and drinks, staining of surfaces, corrosion of metals, minerals, and concrete). R. John Parkes Bibliography Atlas, R. M. and and Bartha, R. (1998) Microbial ecology: fundamentals and applications (4th edn). Benjamin/Cummings, Menlo Park, California. |
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PAUL HANCOCK and BRIAN J. SKINNER. "biodegradation." The Oxford Companion to the Earth. 2000. Encyclopedia.com. 31 May. 2012 <http://www.encyclopedia.com>. PAUL HANCOCK and BRIAN J. SKINNER. "biodegradation." The Oxford Companion to the Earth. 2000. Encyclopedia.com. (May 31, 2012). http://www.encyclopedia.com/doc/1O112-biodegradation.html PAUL HANCOCK and BRIAN J. SKINNER. "biodegradation." The Oxford Companion to the Earth. 2000. Retrieved May 31, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O112-biodegradation.html |
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biodegradable
bi·o·de·grad·a·ble / ˌbīōdiˈgrādəbəl/ • adj. (of a substance or object) capable of being decomposed by bacteria or other living organisms. DERIVATIVES: bi·o·de·grad·a·bil·i·ty / -ˌgrādəˈbilitē/ n. |
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"biodegradable." The Oxford Pocket Dictionary of Current English. 2009. Encyclopedia.com. 31 May. 2012 <http://www.encyclopedia.com>. "biodegradable." The Oxford Pocket Dictionary of Current English. 2009. Encyclopedia.com. (May 31, 2012). http://www.encyclopedia.com/doc/1O999-biodegradable.html "biodegradable." The Oxford Pocket Dictionary of Current English. 2009. Retrieved May 31, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O999-biodegradable.html |
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biodegradable
biodegradable Property of a substance that enables it to be decomposed by microorganisms. The end result of decay is stable, simple compounds (such as water and carbon dioxide). This property has been designed into materials such as plastics to aid refuse disposal and reduce pollution.
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"biodegradable." World Encyclopedia. 2005. Encyclopedia.com. 31 May. 2012 <http://www.encyclopedia.com>. "biodegradable." World Encyclopedia. 2005. Encyclopedia.com. (May 31, 2012). http://www.encyclopedia.com/doc/1O142-biodegradable.html "biodegradable." World Encyclopedia. 2005. Retrieved May 31, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O142-biodegradable.html |
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biodegradable
biodegradable Applied to substances that are easily broken down by living organisms.
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MICHAEL ALLABY. "biodegradable." A Dictionary of Ecology. 2004. Encyclopedia.com. 31 May. 2012 <http://www.encyclopedia.com>. MICHAEL ALLABY. "biodegradable." A Dictionary of Ecology. 2004. Encyclopedia.com. (May 31, 2012). http://www.encyclopedia.com/doc/1O14-biodegradable.html MICHAEL ALLABY. "biodegradable." A Dictionary of Ecology. 2004. Retrieved May 31, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O14-biodegradable.html |
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biodegradable
biodegradable Applied to substances that are easily broken down by living organisms.
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MICHAEL ALLABY. "biodegradable." A Dictionary of Zoology. 1999. Encyclopedia.com. 31 May. 2012 <http://www.encyclopedia.com>. MICHAEL ALLABY. "biodegradable." A Dictionary of Zoology. 1999. Encyclopedia.com. (May 31, 2012). http://www.encyclopedia.com/doc/1O8-biodegradable.html MICHAEL ALLABY. "biodegradable." A Dictionary of Zoology. 1999. Retrieved May 31, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O8-biodegradable.html |
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biodegradable
biodegradable See pollution.
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"biodegradable." A Dictionary of Biology. 2004. Encyclopedia.com. 31 May. 2012 <http://www.encyclopedia.com>. "biodegradable." A Dictionary of Biology. 2004. Encyclopedia.com. (May 31, 2012). http://www.encyclopedia.com/doc/1O6-biodegradable.html "biodegradable." A Dictionary of Biology. 2004. Retrieved May 31, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O6-biodegradable.html |
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