Biodegradation is the decomposition of organic material by microorganisms. It is often used in relation to sewage treatment, environmental remediation (bioremediation) and to plastic materials although biodegradation is perhaps better regarded as the closing of the loop commencing with photosynthesis. Whereas photosynthesis is the process of creating growing matter through the conversion of carbon dioxide (CO₂) and water (H₂O) into plant material through the action of sunlight, biodegradation is the process of converting organic materials back into CO₂ and H₂O through microbial action. This article is in need of attention, please see the talk page. ... Organic has several meanings and related topics. ... A microorganism or microbe is an organism that is so small that it is microscopic (invisible to the naked eye). ... Sewage treatment is the process that removes the majority of the contaminants from waste-water or sewage and produces both a liquid effluent suitable for disposal to the natural environment and a sludge. ... This article needs a complete rewrite for the reasons listed on the talk page. ... Remediation is the removal of pollution or contaminants from land (including sediments in waterways) for the general protection of the environment or, quite commonly, from a brownfield site so that it can be reused. ... Bioremediation can be defined as any process that uses microorganisms or their enzymes to return the environment altered by contaminants to its original condition. ... Plastic bottles for recycling Plastic is a term that covers a range of synthetic or semisynthetic polymerization products. ... Leaf. ... Carbon dioxide is an atmospheric gas comprised of one carbon and two oxygen atoms. ... Water (from the Old English word wæter; c. ...

Biodegradable matter is material that will biodegrade. For example, most plastic bags are not biodegradable, but paper bags are in a general sense. However, paper is usually not biodegradable according to the principal world standards because paper generally contains too many heavy metals to comply. This article needs to be cleaned up to conform to a higher standard of quality. ... For other meanings, see heavy metal The term heavy metal may have various more general or more specific meanings. ...

In managing waste disposal, degradability can make an important difference, because plastic bags stay around forever if left as litter, whereas paper bags will eventually decompose. There is a third category of materials, biodegradable plastics, such as MaterBi, which will biodegrade, while others such as polylactide (PLA) will compost. However, in anaerobic landfills, whether a material is biodegradable makes little difference; biodegradable matter usually does not decay, because of the lack of oxygen required by the microorganisms. However, if biodegradation does occur it is likely to be through an anaerobic process, thus giving rise to methane production as distinct from carbon dioxide production. Methane has approximately 10 times the global warming potential of carbon dioxide. In modern landfills this biogas will be collected and used for power generation. It has been suggested that this article or section be merged into polylactic acid. ... A compost bin full of autumn oak leaves Compost is the decomposed remnants of organic materials (those with plant and animal origins). ... Anaerobic is a technical word which literally means without air. ... Landfill is a waste disposal site for the deposit of the waste onto or into land (i. ... General Name, Symbol, Number oxygen, O, 8 Chemical series nonmetals Group, Period, Block 16, 2, p Appearance colorless Atomic mass 15. ... R-phrases S-phrases , , , Flash point −188 °C Autoignition temperature 537 °C Explosive limits 5–15% Supplementary data page Structure and properties n, εr, etc. ... Biogas typically refers to methane produced by the fermentation of organic matter including manure, wastewater sludge, or municipal solid waste, under anaerobic conditions. ... Itaipu Dam is a hydroelectric generating station Electricity generation is the first process in the delivery of electricity to consumers. ...

A difficulty is that the term biodegradable has both a general meaning and a precise meaning given by different standards bodies. The European Norm EN13432, Japanese Greenpla Standard and the American Society for Testing and Materials (ASTM International) D6400-99 standards all define biodegradability in respect of a time period of 6 months. In the case of EN13432 a material is deemed biodegradable if it will break down to the extent of at least 90% to H₂O and CO₂ and biomass within a period of 6 months. ASTM D6400-99 also imposes a time period of 6 months. Each of the named standards sets limits for the amounts of heavy metals that the material may contain. (Note that DIN V49000 sets the strictest standards, that is, it permits the lowest value of heavy metal presence). A satellite composite image of Europe Europe is the worlds second-smallest continent in terms of area, with an area of 10,600,000 km² (4,140,625 square miles), making it larger than Australia only. ... The word norm coming from the latin word norma which means angle measure or (lawlike) rule, has a number of meanings: A social or sociological norm; see norm (sociology). ... ASTM International is an international voluntary standards organization that develops and produces technical standards for materials, products, systems and services. ... Deutsches Institut für Normung (DIN, the German Institute for Standardization) is a German national organization for standardization. ...

There are plastic materials that claim biodegradability, but are more often (and possibly more accurately) described as 'degradable' or oxy-degradable; these usually utilize one or more heavy metals to promote oxidation and thus disintegration of the polyethylene. It is claimed that this process causes more rapid breakdown of the plastic materials into CO₂ and H₂O although there appears to be no scientific evidence to support this claim. The US-based Biodegradable Products Institute has found alarming levels of heavy metals in some such products. Polyethylene or polyethene is a thermoplastic commodity heavily used in consumer products (over 60M tons are produced worldwide every year). ...

The following table should be read with the above comments in mind, and care should be taken before accepting claims of biodegradability in view of the (dubious) claims being made. This is how long it takes for some commonly used products to biodegrade, when they are scattered about as litter:

Cotton is a soft fiber that grows around the seeds of the cotton plant, a shrub native to the tropical and subtropical regions of both the Old World and the New World. ... Snot Rag is a place to blow your nose A rag is a piece of old cloth used to clean or wipe things. ... Coils of rope used for long-line fishing A rope is a length of fibers, twisted or braided together to improve strength, for pulling and connecting. ... Orange—specifically, sweet orange—refers to the citrus tree Citrus sinensis and its fruit. ... Wool in a shearing shed Long and short hair wool at the South Central Family Farm Research Center in Boonesville, AR Wool is the fiber derived from the hair of domesticated animals, usually sheep. ... A cigarette will burn to ash on one end. ... A glass of cows milk Milk most often means the nutrient fluid produced by the mammary glands of female mammals. ... A carton is a type of packaging, generally for food. ... Modern leather-working tools Leather is a material created through the tanning of hides, pelts and skins of animals, primarily cows. ... Womens shoes on display in a shop window, July 2005 A shoe is an item of footwear. ... This article covers the material nylon. ... Three tin cans of varying sizes; the one on front is opened with a pull tab. ... Aluminum is a soft and lightweight metal with a dull silvery appearance, due to a thin layer of oxidation that forms quickly when it is exposed to air. ... For eyeglasses, see glasses. ... Reusable glass milk bottles A bottle is a small container with a neck that is narrower than the body and a mouth. ...

See also

• biodegradability prediction
• bioremediation
• list of environment topics

Biodegradability prediction is biologically-inspired computing and attempts to predict biodegradability of anthropogenic materials in the environment. ... Bioremediation can be defined as any process that uses microorganisms or their enzymes to return the environment altered by contaminants to its original condition. ... This page aims to list articles related to the natural environment. ...

External links

Worldwise.com: Further reading on biodegradation