Array ( [0] => {{Short description|Decomposition by living organisms}} [1] => {{For|the journal|Biodegradation (journal){{!}}''Biodegradation'' (journal)}} [2] => [3] => [[File:Slime.mold.jpg|thumb|250px|Yellow [[slime mold]] growing on a bin of wet paper]] [4] => '''Biodegradation''' is the breakdown of [[organic matter]] by [[microorganism]]s, such as [[bacteria]] and [[fungi]].{{efn| The [[International Union of Pure and Applied Chemistry|IUPAC]] defines biodegradation as "degradation caused by [[Enzyme|enzymatic]] process resulting from the action of [[Cell (biology)|cells]]" and notes that the definition is "modified to exclude [[abiotic]] enzymatic processes."{{cite journal | vauthors = Vert M, Doi Y, Hellwich KH, Hess M, Hodge P, Kubisa P, Rinaudo M, Schué F | title=Terminology for biorelated polymers and applications (IUPAC Recommendations 2012) |journal=[[Pure and Applied Chemistry]] |year=2012 |volume=84 |issue=2 |pages=377–410 |doi=10.1351/PAC-REC-10-12-04 | s2cid=98107080 |doi-access=free }}}}{{Cite journal |last=Young |first=Reginald |title=Improved, reference quality genome sequence of the plastic-degrading greater wax moth, Galleria mellonella |url=https://academic.oup.com/g3journal/advance-article/doi/10.1093/g3journal/jkae070/7639139?login=true |journal= G3: Genes, Genomes, Genetics|date=2024 |doi=10.1093/g3journal/jkae070|doi-access=free |pmid=38564250 }} It is generally assumed to be a natural process, which differentiates it from [[compost]]ing. Composting is a human-driven process in which biodegradation occurs under a specific set of circumstances. [5] => [6] => The process of biodegradation is threefold: first an object undergoes biodeterioration, which is the mechanical weakening of its structure; then follows biofragmentation, which is the breakdown of materials by microorganisms; and finally assimilation, which is the incorporation of the old material into new cells. [7] => [8] => In practice, almost all chemical compounds and materials are subject to biodegradation, the key element being time. Things like vegetables may degrade within days, while [[glass]] and some [[plastic]]s take many millennia to decompose. A standard for biodegradability used by the [[European Union]] is that greater than 90% of the original material must be converted into {{CO2}}, water and minerals by biological processes within 6 months. [9] => [10] => == Mechanisms == [11] => The process of biodegradation can be divided into three stages: biodeterioration, biofragmentation, and [[assimilation (biology)|assimilation]]. Biodeterioration is sometimes described as a surface-level degradation that modifies the mechanical, physical and chemical properties of the material. This stage occurs when the material is exposed to [[Abiotic component|abiotic]] factors in the outdoor environment and allows for further degradation by weakening the material's structure. Some abiotic factors that influence these initial changes are compression (mechanical), light, temperature and chemicals in the environment.{{cite journal | vauthors = Lucas N, Bienaime C, Belloy C, Queneudec M, Silvestre F, Nava-Saucedo JE | title = Polymer biodegradation: mechanisms and estimation techniques | journal = Chemosphere | volume = 73 | issue = 4 | pages = 429–42 | date = September 2008 | pmid = 18723204 | doi = 10.1016/j.chemosphere.2008.06.064 | bibcode = 2008Chmsp..73..429L }} While biodeterioration typically occurs as the first stage of biodegradation, it can in some cases be parallel to biofragmentation.{{cite book |last=Muller |first=Rolf-Joachim |editor-first=Alexander |editor-last=Steinbüchel |name-list-style=vanc |chapter=Biodegradability of Polymers: Regulations and Methods for Testing |title=Biopolymers |publisher=Wiley-VCH |isbn=978-3-527-30290-1 |chapter-url=https://application.wiley-vch.de/books/biopoly/pdf_v10/vol10_19.pdf |doi=10.1002/3527600035.bpola012 |year=2005 |access-date=2018-09-19 |archive-date=2018-09-19 |archive-url=https://web.archive.org/web/20180919062117/https://application.wiley-vch.de/books/biopoly/pdf_v10/vol10_19.pdf |url-status=dead }} Hueck,{{Cite journal|last=Hueck|first=Hans|date=January 1966|title=The biodeterioration of materials as part of hylobiology|journal=Material und Organismen|volume=1|pages=5–34|via=ISSN 00255270}} however, defined Biodeterioration as the undesirable action of living organisms on Man's materials, involving such things as breakdown of stone facades of buildings,{{Cite book|title=Introduction to Biodeterioration|last=Allsopp|first=Dennis|publisher=Cambridge University Press|year=2004|isbn=9780511617065|location=Cambridge}} corrosion of metals by microorganisms or merely the esthetic changes induced on man-made structures by the growth of living organisms. [12] => [13] => Biofragmentation of a [[polymer]] is the [[lytic]] process in which bonds within a polymer are cleaved, generating [[oligomer]]s and [[monomer]]s in its place. The steps taken to fragment these materials also differ based on the presence of oxygen in the system. The breakdown of materials by microorganisms when oxygen is present is [[aerobic digestion]], and the breakdown of materials when oxygen is not present is [[anaerobic digestion]].{{Cite web|url=http://www.polimernet.com/Docs/Aerobic%20-%20Anaerobic%20Biodegredation%20en.pdf |archive-url=https://web.archive.org/web/20110419204604/http://polimernet.com/Docs/Aerobic%20-%20Anaerobic%20Biodegredation%20en.pdf |archive-date=2011-04-19 |url-status=live|title=Aerobic and Anaerobic Biodegradation| work = Fundamentals of Aerobic & Anaerobic Biodegradation Process | publisher = Polimernet Plastik San. Tic. Ltd. Şti. }} The main difference between these processes is that anaerobic reactions produce [[methane]], while aerobic reactions do not (however, both reactions produce [[carbon dioxide]], [[water]], some type of residue, and a new [[biomass]]).{{Cite web|url=http://edepot.wur.nl/193543|title=Analytical Methods for Monitoring Biodegradation Processes of Environmentally Degradable Polymers|last=Van der Zee|first=Maarten|name-list-style=vanc|date=2011|access-date=2019-01-21|archive-date=2019-02-18|archive-url=https://web.archive.org/web/20190218014545/http://edepot.wur.nl/193543|url-status=live}} In addition, aerobic digestion typically occurs more rapidly than anaerobic digestion, while anaerobic digestion does a better job reducing the volume and mass of the material. Due to anaerobic digestion's ability to reduce the volume and mass of [[waste]] materials and produce a natural gas, anaerobic digestion technology is widely used for [[waste management]] systems and as a source of local, renewable energy.{{Cite journal | last = Klinkner | first = Blake Anthony | name-list-style = vanc | title = Anaerobic Digestion as a Renewable Energy Source and Waste Management Technology: What Must be Done for this Technology to Realize Success in the United States? | url = https://scholarship.law.umassd.edu/cgi/viewcontent.cgi?article=1027&context=umlr | journal = University of Massachusetts Law Review | volume = 9 | pages = 68–96 | year = 2014 | access-date = 2018-09-23 | archive-date = 2020-06-29 | archive-url = https://web.archive.org/web/20200629134555/https://scholarship.law.umassd.edu/cgi/viewcontent.cgi?article=1027&context=umlr | url-status = live }} [14] => [15] => In the assimilation stage, the resulting products from biofragmentation are then integrated into [[microbial cell]]s. Some of the products from fragmentation are easily transported within the cell by [[membrane carrier]]s. However, others still have to undergo biotransformation reactions to yield products that can then be transported inside the cell. Once inside the cell, the products enter [[catabolic pathway]]s that either lead to the production of [[adenosine triphosphate]] (ATP) or elements of the [[anabolism|cells structure]]. [16] => [17] => ;Aerobic biodegradation equation [18] => :C{{sub|polymer}} + O{{sub|2}} → C{{sub|residue}} + C{{sub|biomass}} + CO{{sub|2}} + H{{sub|2}}O [19] => [20] => ;Anaerobic biodegradation equation [21] => :C{{sub|polymer}} → C{{sub|residue}} + C{{sub|biomass}} + CO{{sub|2}} + CH{{sub|4}} + H{{sub|2}}O [22] => [23] => == Factors affecting biodegradation rate == [24] => [[File:Decomposition rates of marine debris items, OWID.svg|thumb|upright=2|Average estimated decomposition times of typical marine debris items. Plastic items are shown in blue.]] [25] => In practice, almost all chemical compounds and materials are subject to biodegradation processes. The significance, however, is in the relative rates of such processes, such as days, weeks, years or centuries. A number of factors determine the rate at which this degradation of organic compounds occurs. Factors include [[light]], [[water]], [[oxygen]] and temperature.{{cite journal | vauthors = Haider T, Völker C, Kramm J, Landfester K, Wurm FR | title = Plastics of the future? The impact of biodegradable polymers on the environment and on society | journal = Angewandte Chemie International Edition in English | volume = 58| issue = 1| pages = 50–62| date = July 2018 | pmid = 29972726 | doi = 10.1002/anie.201805766 | doi-access = free }} The degradation rate of many organic compounds is limited by their [[bioavailability]], which is the rate at which a substance is absorbed into a system or made available at the site of physiological activity,{{Cite web|url=https://www.merriam-webster.com/dictionary/bioavailability|title=Definition of BIOAVAILABILITY|website=www.merriam-webster.com|language=en|access-date=2018-09-19|archive-date=2018-09-19|archive-url=https://web.archive.org/web/20180919062040/https://www.merriam-webster.com/dictionary/bioavailability|url-status=live}} as compounds must be released into solution before organisms can degrade them. The rate of biodegradation can be measured in a number of ways. [[Respirometry]] tests can be used for [[aerobic microbes]]. First one places a solid waste sample in a container with microorganisms and soil, and then aerates the mixture. Over the course of several days, microorganisms digest the sample bit by bit and produce carbon dioxide – the resulting amount of CO2 serves as an indicator of degradation. Biodegradability can also be measured by anaerobic microbes and the amount of methane or alloy that they are able to produce.{{cite web |first=Andy |last=Jessop |name-list-style=vanc |url=https://commercialwaste.trade/how-is-biodegradability-measured/ |title=How is biodegradability measured? |date=2015-09-16 |work=Commercial Waste |access-date=2018-09-19 |archive-date=2018-09-19 |archive-url=https://web.archive.org/web/20180919062141/https://commercialwaste.trade/how-is-biodegradability-measured/ |url-status=live }} [26] => [27] => It's important to note factors that affect biodegradation rates during product testing to ensure that the results produced are accurate and reliable. Several materials will test as being biodegradable under optimal conditions in a lab for approval but these results may not reflect real world outcomes where factors are more variable.{{cite journal |title=Research of the biodegradability of degradable/biodegradable plastic material in various types of environments| vauthors = Adamcova D, Radziemska M, Fronczyk J, Zloch J, Vaverkova MD | journal = Przegląd Naukowy. Inżynieria i Kształtowanie Środowiska | volume = 26 |year=2017|pages=3–14| doi = 10.22630/PNIKS.2017.26.1.01 |doi-access=free}} For example, a material may have tested as biodegrading at a high rate in the lab may not degrade at a high rate in a landfill because landfills often lack light, water, and microbial activity that are necessary for degradation to occur.{{Cite news|url=https://www.sciencelearn.org.nz/resources/1543-measuring-biodegradability|title=Measuring biodegradability|work=Science Learning Hub|access-date=2018-09-19|language=en|archive-date=2018-09-19|archive-url=https://web.archive.org/web/20180919162548/https://www.sciencelearn.org.nz/resources/1543-measuring-biodegradability|url-status=live}} Thus, it is very important that there are standards for plastic biodegradable products, which have a large impact on the environment. The development and use of accurate standard test methods can help ensure that all plastics that are being produced and commercialized will actually biodegrade in natural environments.{{cite book |date=1995 |editor-last=Scott |editor-first=Gerald |editor2-last=Gilead |editor2-first=Dan | name-list-style = vanc |title=Degradable Polymers | publisher = Dordrecht Springer | location = Netherlands | doi = 10.1007/978-94-011-0571-2 |isbn=978-94-010-4253-6 }} One test that has been developed for this purpose is DINV 54900.{{cite journal | vauthors = Witt U, Yamamoto M, Seeliger U, Müller RJ, Warzelhan V | title = Biodegradable Polymeric Materials-Not the Origin but the Chemical Structure Determines Biodegradability | journal = Angewandte Chemie | volume = 38 | issue = 10 | pages = 1438–1442 | date = May 1999 | pmid = 29711570 | doi = 10.1002/(sici)1521-3773(19990517)38:10<1438::aid-anie1438>3.0.co;2-u }} [28] => [29] => {| class="wikitable" [30] => |+Approximated time for compounds to biodegrade in a marine environment[http://cmore.soest.hawaii.edu/cruises/super/biodegradation.htm "Marine Debris Biodegradation Time Line"] {{Webarchive|url=https://web.archive.org/web/20111105113852/http://cmore.soest.hawaii.edu/cruises/super/biodegradation.htm |date=2011-11-05 }}. [[Center for Microbial Oceanography: Research and Education|C-MORE]], citing [[Mote Marine Laboratory]], 1993. [31] => ! scope="col" style="width:175px;"| Product [32] => ! scope="col" style="width:175px;"| Time to Biodegrade [33] => |- [34] => | [[Paper towel]] || 2–4 weeks [35] => |- [36] => | [[Newspaper]] || 6 weeks [37] => |- [38] => | [[Apple core]] || 2 months [39] => |- [40] => | [[Cardboard]] box || 2 months [41] => |- [42] => | Wax coated [[milk carton]] || 3 months [43] => |- [44] => | [[Cotton]] gloves || 1–5 months [45] => |- [46] => | [[Wool]] gloves || 1 year [47] => |- [48] => | [[Plywood]] || 1–3 years [49] => |- [50] => | Painted [[wooden]] sticks || 13 years [51] => |- [52] => | [[Plastic bag]]s || 10–20 years [53] => |- [54] => | [[Tin can]]s || 50 years [55] => |- [56] => | [[Disposable diaper]]s || 50–100 years [57] => |- [58] => | [[Plastic bottle]] || 100 years [59] => |- [60] => | [[Aluminium can]]s || 200 years [61] => |- [62] => | [[Glass bottle]]s || Undetermined [63] => |} [64] => [65] => {| class="wikitable" [66] => |+Time-frame for common items to break down in a terrestrial environment [67] => |Vegetables [68] => |5 days – 1 month [69] => |- [70] => |Paper [71] => |2–5 months [72] => |- [73] => |Cotton T-shirt [74] => |6 months [75] => |- [76] => |Orange peels [77] => |6 months [78] => |- [79] => |Tree leaves [80] => |1 year [81] => |- [82] => |Wool socks [83] => |1–5 years [84] => |- [85] => |[[Plastic-coated paper]] milk cartons [86] => |5 years [87] => |- [88] => |[[Leather]] [[shoes]] [89] => |25–40 years [90] => |- [91] => |[[Nylon]] fabric [92] => |30–40 years [93] => |- [94] => |Tin cans [95] => |50–100 years [96] => |- [97] => |Aluminium cans [98] => |80–100 years [99] => |- [100] => |Glass bottles [101] => |1 million years [102] => |- [103] => |[[Styrofoam cup]] [104] => |500 years to forever [105] => |- [106] => |Plastic bags [107] => |500 years to forever [108] => |} [109] => [110] => == Plastics == [111] => {{Main|Biodegradable plastic#Examples of biodegradable plastics}} [112] => [113] => The term Biodegradable Plastics refers to materials that maintain their mechanical strength during practical use but break down into low-weight compounds and non-toxic byproducts after their use.{{cite journal |last1=Ikada |first1=Yoshito |last2=Tsuji |first2=Hideto |name-list-style=vanc |date=February 2000 |title=Biodegradable polyesters for medical and ecological applications |journal=Macromolecular Rapid Communications |volume=21 |issue=3 |pages=117–132 |doi=10.1002/(sici)1521-3927(20000201)21:3<117::aid-marc117>3.0.co;2-x |url=http://web.mit.edu/course/10/10.569/www/ikadaPEreview.pdf |access-date=2011-03-08 |archive-date=2016-03-05 |archive-url=https://web.archive.org/web/20160305143418/http://web.mit.edu/course/10/10.569/www/ikadaPEreview.pdf |url-status=live }} This breakdown is made possible through an attack of microorganisms on the material, which is typically a non-water-soluble polymer. Such materials can be obtained through chemical synthesis, fermentation by microorganisms, and from chemically modified natural products.{{cite journal | vauthors = Flieger M, Kantorová M, Prell A, Rezanka T, Votruba J | title = Biodegradable plastics from renewable sources | journal = Folia Microbiologica | volume = 48 | issue = 1 | pages = 27–44 | date = January 2003 | pmid = 12744074 | doi = 10.1007/bf02931273 | s2cid = 32800851 }} [114] => [115] => [[Plastics]] biodegrade at highly variable rates. [[Polyvinylchloride|PVC]]-based plumbing is selected for handling [[sewage]] because PVC resists biodegradation. Some packaging materials on the other hand are being developed that would degrade readily upon exposure to the environment.{{cite journal |last1=Kyrikou |first1=Ioanna |last2=Briassoulis |first2=Demetres | name-list-style = vanc |date=12 Apr 2007 |title=Biodegradation of Agricultural Plastic Films: A Critical Review |journal=Journal of Polymers and the Environment |volume=15 |issue=2 |pages=125–150 |doi= 10.1007/s10924-007-0053-8 |s2cid=195331133 }} Examples of [[synthetic polymer]]s that biodegrade quickly include [[polycaprolactone]], other [[polyesters]] and aromatic-aliphatic esters, due to their ester bonds being susceptible to attack by water. A prominent example is [[poly-3-hydroxybutyrate]], the renewably derived [[polylactic acid]]. Others are the cellulose-based cellulose acetate and celluloid (cellulose nitrate). [116] => [117] => :[[File:Polylactid sceletal.svg|thumb|150px|[[Polylactic acid]] is an example of a plastic that biodegrades quickly.]] [118] => Under [[anaerobic decomposition|low oxygen]] conditions plastics break down more slowly. The breakdown process can be accelerated in specially designed [[compost | compost heap]]. Starch-based plastics will degrade within two to four months in a home compost bin, while polylactic acid is largely undecomposed, requiring higher temperatures.{{cite web|url=http://www3.imperial.ac.uk/pls/portallive/docs/1/33773706.PDF |archive-url=https://web.archive.org/web/20130602155241/http://www3.imperial.ac.uk/pls/portallive/docs/1/33773706.PDF |archive-date=2013-06-02 |url-status=live |title= Section 6: Biodegradability of Packaging Waste |publisher=Www3.imperial.ac.uk |access-date=2014-03-02}} Polycaprolactone and polycaprolactone-starch composites decompose slower, but the starch content accelerates decomposition by leaving behind a porous, high surface area polycaprolactone. Nevertheless, it takes many months.{{cite journal |last1=Wu |first1=Chin-San |name-list-style=vanc |title=Physical properties and biodegradability of maleated-polycaprolactone/starch composite |journal=Polymer Degradation and Stability |date=January 2003 |volume=80 |issue=1 |pages=127–134 |doi=10.1016/S0141-3910(02)00393-2 |url=http://www.kyu.edu.tw/93/epaperv6/93-129.pdf |citeseerx=10.1.1.453.4220 |access-date=2012-06-23 |archive-date=2016-03-04 |archive-url=https://web.archive.org/web/20160304072701/http://www.kyu.edu.tw/93/epaperv6/93-129.pdf |url-status=dead }} [119] => [120] => In 2016, a bacterium named ''[[Ideonella sakaiensis]]'' was found to biodegrade [[Polyethylene terephthalate|PET]]. In 2020, the PET degrading enzyme of the bacterium, [[PETase]], has been genetically modified and combined with [[MHETase]] to break down PET faster, and also degrade [[Polyethylene 2,5-furandicarboxylate|PEF]].{{cite news |last1=Carrington |first1=Damian |title=New super-enzyme eats plastic bottles six times faster |url=https://www.theguardian.com/environment/2020/sep/28/new-super-enzyme-eats-plastic-bottles-six-times-faster |access-date=12 October 2020 |work=The Guardian |date=28 September 2020 |archive-date=12 October 2020 |archive-url=https://web.archive.org/web/20201012004245/https://www.theguardian.com/environment/2020/sep/28/new-super-enzyme-eats-plastic-bottles-six-times-faster |url-status=live }}{{cite news |title=Plastic-eating enzyme 'cocktail' heralds new hope for plastic waste |url=https://phys.org/news/2020-09-plastic-eating-enzyme-cocktail-heralds-plastic.html |access-date=12 October 2020 |work=phys.org |language=en |archive-date=11 October 2020 |archive-url=https://web.archive.org/web/20201011210353/https://phys.org/news/2020-09-plastic-eating-enzyme-cocktail-heralds-plastic.html |url-status=live }}{{cite journal |last1=Knott |first1=Brandon C. |last2=Erickson |first2=Erika |last3=Allen |first3=Mark D. |last4=Gado |first4=Japheth E. |last5=Graham |first5=Rosie |last6=Kearns |first6=Fiona L. |last7=Pardo |first7=Isabel |last8=Topuzlu |first8=Ece |last9=Anderson |first9=Jared J. |last10=Austin |first10=Harry P. |last11=Dominick |first11=Graham |last12=Johnson |first12=Christopher W. |last13=Rorrer |first13=Nicholas A. |last14=Szostkiewicz |first14=Caralyn J. |last15=Copié |first15=Valérie |last16=Payne |first16=Christina M. |last17=Woodcock |first17=H. Lee |last18=Donohoe |first18=Bryon S. |last19=Beckham |first19=Gregg T. |last20=McGeehan |first20=John E. |title=Characterization and engineering of a two-enzyme system for plastics depolymerization |journal=Proceedings of the National Academy of Sciences |date=24 September 2020 |volume=117 |issue=41 |pages=25476–25485 |doi=10.1073/pnas.2006753117 |pmid=32989159 |pmc=7568301 |bibcode=2020PNAS..11725476K |language=en |issn=0027-8424|doi-access=free }} In 2021, researchers reported that a mix of microorganisms from [[Cattle#Digestive system|cow stomachs]] could break down three types of plastics.{{cite news |last1=Spary |first1=Sara |title=Cows' stomachs can break down plastic, study finds |url=https://edition.cnn.com/2021/07/02/world/cows-plastic-scli-intl-scn/index.html |access-date=14 August 2021 |work=CNN |archive-date=14 August 2021 |archive-url=https://web.archive.org/web/20210814141350/https://edition.cnn.com/2021/07/02/world/cows-plastic-scli-intl-scn/index.html |url-status=live }}{{cite journal |last1=Quartinello |first1=Felice |last2=Kremser |first2=Klemens |last3=Schoen |first3=Herta |last4=Tesei |first4=Donatella |last5=Ploszczanski |first5=Leon |last6=Nagler |first6=Magdalena |last7=Podmirseg |first7=Sabine M. |last8=Insam |first8=Heribert |last9=Piñar |first9=Guadalupe |last10=Sterflingler |first10=Katja |last11=Ribitsch |first11=Doris |last12=Guebitz |first12=Georg M. |title=Together Is Better: The Rumen Microbial Community as Biological Toolbox for Degradation of Synthetic Polyesters |journal=Frontiers in Bioengineering and Biotechnology |date=2021 |volume=9 |doi=10.3389/fbioe.2021.684459 |language=English |issn=2296-4185|doi-access=free }} [121] => [122] => Many [[plastic producer]]s have gone so far even to say that their plastics are compostable, typically listing [[corn starch]] as an ingredient. However, these claims are questionable because the [[plastics industry]] operates under its own definition of compostable: [123] => :"that which is capable of undergoing biological decomposition in a compost site such that the material is not visually distinguishable and breaks down into carbon dioxide, water, inorganic compounds and biomass at a rate consistent with known compostable materials." (Ref: [[ASTM]] D 6002){{cite web |url=http://www.compostable.info/compostable.htm |title=Compostable |publisher=Compostable.info |access-date=2014-03-02 |archive-date=2020-11-12 |archive-url=https://web.archive.org/web/20201112012056/http://www.compostable.info/compostable.htm |url-status=live }} [124] => [125] => The term "composting" is often used informally to describe the biodegradation of packaging materials. Legal definitions exist for compostability, the process that leads to compost. Four criteria are offered by the European Union:{{cite web|title=Requirements of the EN 13432 standard |url= https://docs.european-bioplastics.org/publications/bp/EUBP_BP_En_13432.pdf |archive-url=https://web.archive.org/web/20180924190657/https://docs.european-bioplastics.org/publications/bp/EUBP_BP_En_13432.pdf |archive-date=2018-09-24 |url-status=live | date = April 2015| work = European Bioplastics |access-date=July 22, 2017|location=Brussels, Belgium}}{{cite book | vauthors = Breulmann M, Künkel A, Philipp S, Reimer V, Siegenthaler KO, Skupin G, Yamamoto M | chapter = Polymers, Biodegradable | title = Ullmann's Encyclopedia of Industrial Chemistry | year = 2012 | publisher = Wiley-VCH | location = Weinheim | doi = 10.1002/14356007.n21_n01 | isbn = 978-3527306732 }} [126] => #'''Chemical composition''': volatile matter and heavy metals as well as fluorine should be limited. [127] => #'''Biodegradability''': the conversion of >90% of the original material into {{CO2}}, water and minerals by biological processes within 6 months. [128] => #'''Disintegrability''': at least 90% of the original mass should be decomposed into particles that are able to pass through a 2x2 mm sieve. [129] => #'''Quality''': absence of toxic substances and other substances that impede composting. [130] => [131] => == Biodegradable technology == [132] => Biodegradable technology is established technology with some applications in product [[packaging]], production, and medicine.{{cite journal | vauthors = Gross RA, Kalra B | title = Biodegradable polymers for the environment | journal = Science | volume = 297 | issue = 5582 | pages = 803–7 | date = August 2002 | pmid = 12161646 | doi = 10.1126/science.297.5582.803 | url = https://zenodo.org/record/1231185 | bibcode = 2002Sci...297..803G | access-date = 2019-06-27 | archive-date = 2020-07-25 | archive-url = https://web.archive.org/web/20200725075829/https://zenodo.org/record/1231185 | url-status = live }} The chief barrier to widespread implementation is the trade-off between biodegradability and performance. For example, lactide-based plastics are inferior packaging properties in comparison to traditional materials. [133] => [134] => Oxo-biodegradation is defined by [[European Committee for Standardization|CEN]] (the European Standards Organisation) as "degradation resulting from [[oxidative]] and cell-mediated phenomena, either simultaneously or successively." While sometimes described as "oxo-fragmentable," and "oxo-degradable" these terms describe only the first or oxidative phase and should not be used for material which degrades by the process of oxo-biodegradation defined by CEN: the correct description is "oxo-biodegradable." Oxo-biodegradable formulations accelerate the biodegradation process but it takes considerable skill and experience to balance the ingredients within the formulations so as to provide the product with a useful life for a set period, followed by degradation and biodegradation.{{cite journal | vauthors = Agamuthu P, Faizura PN | title = Biodegradability of degradable plastic waste | journal = Waste Management & Research | volume = 23 | issue = 2 | pages = 95–100 | date = April 2005 | pmid = 15864950 | doi = 10.1177/0734242X05051045 | bibcode = 2005WMR....23...95A | s2cid = 2552973 }} [135] => [136] => Biodegradable technology is especially utilized by the [[bio-medical]] community. Biodegradable polymers are classified into three groups: [137] => medical, ecological, and dual application, while in terms of origin they are divided into two groups: natural and synthetic. The Clean Technology Group is exploiting the use of [[supercritical carbon dioxide]], which under high pressure at room temperature is a solvent that can use biodegradable plastics to make polymer drug coatings. The polymer (meaning a material composed of molecules with repeating structural units that form a long chain) is used to encapsulate a drug prior to injection in the body and is based on [[lactic acid]], a compound normally produced in the body, and is thus able to be excreted naturally. The coating is designed for controlled release over a period of time, reducing the number of injections required and maximizing the therapeutic benefit. Professor Steve Howdle states that biodegradable polymers are particularly attractive for use in [[drug delivery]], as once introduced into the body they require no retrieval or further manipulation and are degraded into soluble, non-toxic by-products. Different polymers degrade at different rates within the body and therefore polymer selection can be tailored to achieve desired release rates.{{cite web | title = Using Green Chemistry to Deliver Cutting Edge Drugs | author = The University of Nottingham | url = https://www.sciencedaily.com/releases/2007/09/070913132945.htm | work = Science Daily | date = September 13, 2007 | access-date = September 24, 2018 | archive-date = September 24, 2018 | archive-url = https://web.archive.org/web/20180924070721/https://www.sciencedaily.com/releases/2007/09/070913132945.htm | url-status = live }} [138] => [139] => Other biomedical applications include the use of biodegradable, elastic shape-memory polymers. Biodegradable implant materials can now be used for minimally invasive surgical procedures through degradable thermoplastic polymers. These polymers are now able to change their shape with increase of temperature, causing shape memory capabilities as well as easily degradable sutures. As a result, implants can now fit through small incisions, doctors can easily perform complex deformations, and sutures and other material aides can naturally biodegrade after a completed surgery.{{cite journal | vauthors = Lendlein A, Langer R | title = Biodegradable, elastic shape-memory polymers for potential biomedical applications | journal = Science | volume = 296 | issue = 5573 | pages = 1673–6 | date = May 2002 | pmid = 11976407 | doi = 10.1126/science.1066102 | bibcode = 2002Sci...296.1673L | s2cid = 21801034 | doi-access = free }} [140] => [141] => == Biodegradation vs. composting == [142] => There is no universal definition for biodegradation and there are various definitions of [[composting]], which has led to much confusion between the terms. They are often lumped together; however, they do not have the same meaning. Biodegradation is the naturally-occurring breakdown of materials by microorganisms such as bacteria and fungi or other biological activity.{{cite journal |last1=Gómez |first1=Eddie F. |last2=Michel |first2=Frederick C. | name-list-style = vanc |title=Biodegradability of conventional and bio-based plastics and natural fiber composites during composting, anaerobic digestion and long-term soil incubation |journal=Polymer Degradation and Stability |date=December 2013 |volume=98 |issue=12 |pages=2583–2591 |doi=10.1016/j.polymdegradstab.2013.09.018}} Composting is a human-driven process in which biodegradation occurs under a specific set of circumstances.{{Cite web|url=https://bpiworld.org/Composting|title=Biodegradable Products Institute - Composting|website=bpiworld.org|language=en|access-date=2018-09-24|archive-date=2018-09-24|archive-url=https://web.archive.org/web/20180924185940/https://bpiworld.org/Composting|url-status=live}} The predominant difference between the two is that one process is naturally-occurring and one is human-driven. [143] => [144] => Biodegradable material is capable of decomposing without an oxygen source (anaerobically) into carbon dioxide, water, and biomass, but the timeline is not very specifically defined. Similarly, compostable material breaks down into carbon dioxide, water, and biomass; however, compostable material also breaks down into inorganic compounds. The process for composting is more specifically defined, as it is controlled by humans. Essentially, composting is an accelerated biodegradation process due to optimized circumstances.{{Cite journal|last=Magdoff|first=Fred | name-list-style = vanc |date= November 1993 |title=Building Soils for Better Crops |journal=Soil Science |volume=156 |issue=5 |pages=371 |doi=10.1097/00010694-199311000-00014 |bibcode=1993SoilS.156..371M }} Additionally, the end product of composting not only returns to its previous state, but also generates and adds beneficial microorganisms to the soil called [[humus]]. This organic matter can be used in gardens and on farms to help grow healthier plants in the future.{{Cite journal|url=https://www.accessscience.com/content/325510|title=Humus|last1=Morris|first1=Schnitzer|last2=Martin|first2=James P.|name-list-style=vanc|journal=AccessScience|doi=10.1036/1097-8542.325510|s2cid=242577363|access-date=2018-09-24|archive-date=2018-09-24|archive-url=https://web.archive.org/web/20180924190705/https://www.accessscience.com/content/325510|url-status=live}} Composting more consistently occurs within a shorter time frame since it is a more defined process and is expedited by human intervention. Biodegradation can occur in different time frames under different circumstances, but is meant to occur naturally without human intervention. [145] => [[File:Organic Waste Disposal Streams.pdf|thumb|This figure represents the different paths of disposal for organic waste.{{cite book | vauthors = Kranert M, Behnsen A, Schultheis A, Steinbach D | chapter =Composting in the Framework of the EU Landfill Directive |date=2002 | title = Microbiology of Composting |pages=473–486 |publisher=Springer Berlin Heidelberg |doi=10.1007/978-3-662-08724-4_39 |isbn=9783642087059 }}]] [146] => Even within composting, there are different circumstances under which this can occur. The two main types of composting are at-home versus commercial. Both produce healthy soil to be reused - the main difference lies in what materials are able to go into the process. At-home composting is mostly used for food scraps and excess garden materials, such as weeds. Commercial composting is capable of breaking down more complex plant-based products, such as corn-based plastics and larger pieces of material, like tree branches. Commercial composting begins with a manual breakdown of the materials using a grinder or other machine to initiate the process. Because at-home composting usually occurs on a smaller scale and does not involve large machinery, these materials would not fully decompose in at-home composting. Furthermore, one study has compared and contrasted home and industrial composting, concluding that there are advantages and disadvantages to both.{{cite journal | vauthors = Martínez-Blanco J, Colón J, Gabarrell X, Font X, Sánchez A, Artola A, Rieradevall J | title = The use of life cycle assessment for the comparison of biowaste composting at home and full scale | journal = Waste Management | volume = 30 | issue = 6 | pages = 983–94 | date = June 2010 | pmid = 20211555 | doi = 10.1016/j.wasman.2010.02.023 | bibcode = 2010WaMan..30..983M | url = http://ddd.uab.cat/record/163720 | type = Submitted manuscript | access-date = 2018-09-27 | archive-date = 2019-04-01 | archive-url = https://web.archive.org/web/20190401015646/https://ddd.uab.cat/record/163720 | url-status = live }} [147] => [148] => The following studies provide examples in which composting has been defined as a subset of biodegradation in a scientific context. The first study, "Assessment of Biodegradability of Plastics Under Simulated Composting Conditions in a Laboratory Test Setting," clearly examines composting as a set of circumstances that falls under the category of degradation.{{cite journal | vauthors = Starnecker A, Menner M |date=1996-01-01|title=Assessment of biodegradability of plastics under simulated composting conditions in a laboratory test system |journal=International Biodeterioration & Biodegradation|language=en|volume=37|issue=1–2|pages=85–92|doi=10.1016/0964-8305(95)00089-5 }} Additionally, this next study looked at the biodegradation and composting effects of chemically and physically crosslinked polylactic acid.{{Cite journal|date=2012-02-01|title=Some composting and biodegradation effects of physically or chemically crosslinked poly(lactic acid) |journal=Polymer Testing |volume=31|issue=1|pages=83–92|doi=10.1016/j.polymertesting.2011.09.012 |last1=Żenkiewicz |first1=Marian |last2=Malinowski |first2=Rafał |last3=Rytlewski |first3=Piotr |last4=Richert |first4=Agnieszka |last5=Sikorska |first5=Wanda |last6=Krasowska |first6=Katarzyna | name-list-style = vanc |doi-access=free }} Notably discussing composting and biodegrading as two distinct terms. The third and final study reviews European standardization of biodegradable and compostable material in the packaging industry, again using the terms separately.{{Cite journal | vauthors = Avella M, Bonadies E, Martuscelli E, Rimedio R |date=2001-01-01|title=European current standardization for plastic packaging recoverable through composting and biodegradation |journal=Polymer Testing|language=en|volume=20|issue=5|pages=517–521|doi=10.1016/S0142-9418(00)00068-4 }} [149] => [150] => The distinction between these terms is crucial because [[waste management]] confusion leads to improper disposal of materials by people on a daily basis. Biodegradation technology has led to massive improvements in how we dispose of waste; there now exist trash, recycling, and compost bins in order to optimize the disposal process. However, if these waste streams are commonly and frequently confused, then the disposal process is not at all optimized.{{cite journal | vauthors = Akullian A, Karp C, Austin K, Durbin D | title = Plastic Bag Externalities and Policy in Rhode Island | url = http://seattlebagtax.org/referencedpdfs/en-akullianetal.pdf | journal = Brown Policy Review | year = 2006 | access-date = 2018-09-24 | archive-date = 2017-05-19 | archive-url = https://web.archive.org/web/20170519204013/http://seattlebagtax.org/referencedpdfs/en-akullianetal.pdf | url-status = live }} Biodegradable and compostable materials have been developed to ensure more of human waste is able to breakdown and return to its previous state, or in the case of composting even add nutrients to the ground.{{cite journal | vauthors = Song JH, Murphy RJ, Narayan R, Davies GB | title = Biodegradable and compostable alternatives to conventional plastics | journal = Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences | volume = 364 | issue = 1526 | pages = 2127–39 | date = July 2009 | pmid = 19528060 | pmc = 2873018 | doi = 10.1098/rstb.2008.0289 }} When a compostable product is thrown out as opposed to composted and sent to a landfill, these inventions and efforts are wasted. Therefore, it is important for citizens to understand the difference between these terms so that materials can be disposed of properly and efficiently. [151] => [152] => == Environmental and social effects == [153] => [[Plastic pollution]] from illegal dumping poses health risks to wildlife. Animals often mistake plastics for food, resulting in intestinal entanglement. Slow-degrading chemicals, like polychlorinated biphenyls (PCBs), nonylphenol (NP), and pesticides also found in plastics, can release into environments and subsequently also be ingested by wildlife.{{Cite journal |last1=Webb |first1=Hayden |last2=Arnott |first2=Jaimys |last3=Crawford |first3=Russell |last4=Ivanova |first4=Elena |last5=Webb |first5=Hayden K. |last6=Arnott |first6=Jaimys |last7=Crawford |first7=Russell J. |last8=Ivanova|first8=Elena P. | name-list-style = vanc |date=2012-12-28|title=Plastic Degradation and Its Environmental Implications with Special Reference to Poly(ethylene terephthalate) |journal=Polymers |volume=5 |issue=1 |pages=1–18 |doi=10.3390/polym5010001 |doi-access=free }} [154] => [155] => These chemicals also play a role in human health, as consumption of tainted food (in processes called biomagnification and bioaccumulation) has been linked to issues such as cancers,{{cite journal | vauthors = Kelly BC, Ikonomou MG, Blair JD, Morin AE, Gobas FA | title = Food web-specific biomagnification of persistent organic pollutants | journal = Science | volume = 317 | issue = 5835 | pages = 236–9 | date = July 2007 | pmid = 17626882 | doi = 10.1126/science.1138275 | bibcode = 2007Sci...317..236K | s2cid = 52835862 }} neurological dysfunction,{{cite journal | vauthors = Passos CJ, Mergler D | title = Human mercury exposure and adverse health effects in the Amazon: a review | journal = Cadernos de Saude Publica | volume = 24 | pages = s503–20 | date = 2008 | issue = Suppl 4 | pmid = 18797727 | doi=10.1590/s0102-311x2008001600004| doi-access = free }} and hormonal changes. A well-known example of biomagnification impacting health in recent times is the increased exposure to dangerously high levels of [[mercury in fish]], which can affect sex hormones in humans.{{cite journal | vauthors = Rana SV | title = Perspectives in endocrine toxicity of heavy metals--a review | journal = Biological Trace Element Research | volume = 160 | issue = 1 | pages = 1–14 | date = July 2014 | pmid = 24898714 | doi = 10.1007/s12011-014-0023-7 | s2cid = 18562345 }} [156] => [157] => In efforts to remediate the damages done by slow-degrading plastics, detergents, metals, and other pollutants created by humans, economic costs have become a concern. Marine litter in particular is notably difficult to quantify and review.{{cite book |last1=Newman |first1=Stephanie |last2=Watkins |first2=Emma |last3=Farmer |first3=Andrew |last4=Brink |first4=Patrick ten |last5=Schweitzer |first5=Jean-Pierre | name-list-style = vanc | chapter = The Economics of Marine Litter|date=2015 | title =Marine Anthropogenic Litter |pages=367–394 |publisher=Springer International Publishing |doi=10.1007/978-3-319-16510-3_14 |isbn=978-3-319-16509-7 }} Researchers at the [[World Trade Institute]] estimate that cleanup initiatives' cost (specifically in ocean ecosystems) has hit close to thirteen billion dollars a year.{{cite news | first = Elizabeth | last = Matsangou | name-list-style = vanc | date = 2 July 2018 | url = https://www.worldfinance.com/markets/counting-the-cost-of-plastic-pollution | title = Counting the cost of plastic pollution | access-date = 17 September 2018 | work = World Finance | archive-date = 17 September 2018 | archive-url = https://web.archive.org/web/20180917215550/https://www.worldfinance.com/markets/counting-the-cost-of-plastic-pollution | url-status = live }} The main concern stems from marine environments, with the biggest cleanup efforts centering around garbage patches in the ocean. In 2017, a [[Great Pacific garbage patch|garbage patch the size of Mexico]] was found in the Pacific Ocean. It is estimated to be upwards of a million square miles in size. While the patch contains more obvious examples of litter (plastic bottles, cans, and bags), tiny [[microplastics]] are nearly impossible to clean up.{{cite journal | vauthors = Rochman CM, Cook AM, Koelmans AA | title = Plastic debris and policy: Using current scientific understanding to invoke positive change | journal = Environmental Toxicology and Chemistry | volume = 35 | issue = 7 | pages = 1617–26 | date = July 2016 | pmid = 27331654 | doi = 10.1002/etc.3408 | doi-access = free }} ''National Geographic'' reports that even more non-biodegradable materials are finding their way into vulnerable environments - nearly thirty-eight million pieces a year.{{cite news | first = Shaena | last = Montanari | name-list-style = vanc | url = https://news.nationalgeographic.com/2017/07/ocean-plastic-patch-south-pacific-spd/ | title = Plastic Garbage Patch Bigger Than Mexico Found in Pacific | date = 2017-07-25 | access-date = 2018-09-17 | work = National Geographic | archive-date = 2018-09-17 | archive-url = https://web.archive.org/web/20180917215457/https://news.nationalgeographic.com/2017/07/ocean-plastic-patch-south-pacific-spd/ | url-status = dead }} [158] => [159] => Materials that have not degraded can also serve as shelter for invasive species, such as tube worms and barnacles. When the ecosystem changes in response to the invasive species, resident species and the natural balance of resources, genetic diversity, and species richness is altered.{{cite journal | vauthors = Gregory MR | title = Environmental implications of plastic debris in marine settings--entanglement, ingestion, smothering, hangers-on, hitch-hiking and alien invasions | journal = Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences | volume = 364 | issue = 1526 | pages = 2013–25 | date = July 2009 | pmid = 19528053 | pmc = 2873013 | doi = 10.1098/rstb.2008.0265 }} These factors may support local economies in way of hunting and aquaculture, which suffer in response to the change.{{cite journal | vauthors = Villarrubia-Gómez P, Cornell SE, Fabres J |date=2018-10-01|title=Marine plastic pollution as a planetary boundary threat – The drifting piece in the sustainability puzzle |journal=Marine Policy|language=en|volume=96|pages=213–220|doi=10.1016/j.marpol.2017.11.035 |doi-access=free}} Similarly, coastal communities which rely heavily on [[ecotourism]] lose revenue thanks to a buildup of pollution, as their beaches or shores are no longer desirable to travelers. The World Trade Institute also notes that the communities who often feel most of the effects of poor biodegradation are poorer countries without the means to pay for their cleanup. In a positive feedback loop effect, they in turn have trouble controlling their own pollution sources.{{cite journal | vauthors = Hajat A, Hsia C, O'Neill MS | title = Socioeconomic Disparities and Air Pollution Exposure: a Global Review | journal = Current Environmental Health Reports | volume = 2 | issue = 4 | pages = 440–50 | date = December 2015 | pmid = 26381684 | pmc = 4626327 | doi = 10.1007/s40572-015-0069-5 }} [160] => [161] => == Etymology of "biodegradable" == [162] => The first known use of ''biodegradable'' in a biological context was in 1959 when it was employed to describe the breakdown of material into innocuous components by [[microorganisms]].{{Cite web|url=https://www.merriam-webster.com/dictionary/biodegradable|title=Definition of BIODEGRADABLE|website=www.merriam-webster.com|language=en|access-date=2018-09-24|archive-date=2018-09-24|archive-url=https://web.archive.org/web/20180924190238/https://www.merriam-webster.com/dictionary/biodegradable|url-status=live}} Now ''biodegradable'' is commonly associated with environmentally friendly products that are part of the earth's innate cycles like the [[carbon cycle]] and capable of decomposing back into natural elements. [163] => [164] => == See also == [165] => {{Portal|Ecology|Environment}} [166] => {{columns-list|colwidth=30em| [167] => * [[Anaerobic digestion]] [168] => * [[Assimilation (biology)]] [169] => * [[Bioaccumulation]] [170] => * [[Biodegradability prediction]] [171] => * [[Biodegradable electronics]] [172] => * [[Biodegradable polythene film]] [173] => * [[Biodegradation (journal)|''Biodegradation'' (journal)]] [174] => * [[Biomagnification]] [175] => * [[Bioplastic]] – biodegradable, bio-based plastics [176] => * [[Bioremediation]] [177] => * [[Decomposition]] – reduction of the body of a formerly living organism into simpler forms of matter [178] => * [[Landfill gas monitoring]] [179] => * [[List of environment topics]] [180] => * [[Microbial biodegradation]] [181] => * [[Photodegradation]] [182] => }} [183] => [184] => == Notes == [185] => {{notelist}} [186] => [187] => == References == [188] => {{Reflist}} [189] => [190] => === Standards by ASTM International === [191] => *D5210- Standard Test Method for Determining the Anaerobic Biodegradation of Plastic Materials in the Presence of Municipal Sewage Sludge [192] => *D5526- Standard Test Method for Determining Anaerobic Biodegradation of Plastic Materials Under Accelerated Landfill Conditions [193] => *D5338- Standard Test Method for Determining Aerobic Biodegradation of Plastic Materials Under Controlled Composting Conditions, Incorporating Thermophilic Temperatures [194] => *D5511- Standard Test Method for Determining Anaerobic Biodegradation of Plastic Materials Under High-Solids Anaerobic-Digestion Conditions [195] => *D5864- Standard Test Method for Determining Aerobic Aquatic Biodegradation of Lubricants or Their Components [196] => *D5988- Standard Test Method for Determining Aerobic Biodegradation of Plastic Materials in Soil [197] => *D6139- Standard Test Method for Determining the Aerobic Aquatic Biodegradation of Lubricants or Their Components Using the Gledhill Shake Flask [198] => *D6006- Standard Guide for Assessing Biodegradability of Hydraulic Fluids [199] => *D6340- Standard Test Methods for Determining Aerobic Biodegradation of Radiolabeled Plastic Materials in an Aqueous or Compost Environment [200] => *D6691- Standard Test Method for Determining Aerobic Biodegradation of Plastic Materials in the Marine Environment by a Defined Microbial Consortium or Natural Sea Water Inoculum [201] => *D6731-Standard Test Method for Determining the Aerobic, Aquatic Biodegradability of Lubricants or Lubricant Components in a Closed Respirometer [202] => *D6954- Standard Guide for Exposing and Testing Plastics that Degrade in the Environment by a Combination of Oxidation and Biodegradation [203] => *D7044- Standard Specification for Biodegradable Fire Resistant Hydraulic Fluids [204] => *D7373-Standard Test Method for Predicting Biodegradability of Lubricants Using a Bio-kinetic Model [205] => *D7475- Standard Test Method for Determining the Aerobic Degradation and Anaerobic Biodegradation of Plastic Materials under Accelerated Bioreactor Landfill Conditions [206] => *D7665- Standard Guide for Evaluation of Biodegradable Heat Transfer Fluids [207] => [208] => == External links == [209] => *[http://www.european-bioplastics.org/ European Bioplastics Association] [210] => *[https://web.archive.org/web/20130723014926/http://www.fpintl.com/resources/wp_biodegradable_plastics.htm The Science of Biodegradable Plastics: The Reality Behind Biodegradable Plastic Packaging Material] [211] => *[http://www.biosphereplastic.com/uncategorized/what-is-biodegradation/ Biodegradable Plastic Definition] [212] => [213] => {{Waste}} [214] => {{Authority control}} [215] => [216] => [[Category:Biodegradation| ]] [217] => [[Category:Anaerobic digestion]] [218] => [[Category:Biodegradable waste management]] [] => )
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Biodegradation

Biodegradation is the breakdown of organic matter by microorganisms, such as bacteria and fungi. It is generally assumed to be a natural process, which differentiates it from composting.

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