Editing Landfill

{{Short description|Site for the disposal of waste materials}}
{{About||the practice of filling a body of water to create new land|Land reclamation|other uses}}
{{Use mdy dates|date=July 2019}}
{{Pollution sidebar|Solid waste}}

A '''landfill'''{{efn|Also known as a '''tip''', '''dump''', '''rubbish tip''', '''rubbish dump''', '''garbage dump''', '''trash dump''', or '''dumping ground'''.}} is a site for the disposal of [[waste]] materials. It is the oldest and most common form of [[waste disposal]], although the systematic burial of waste with daily, intermediate and final covers only began in the 1940s. In the past, waste was simply left in piles or thrown into pits (known in [[Archaeology|archeology]] as [[midden]]s).

Landfills take up a lot of land and pose environmental risks. Some landfill sites are used for waste management purposes, such as temporary storage, consolidation and transfer, or for various stages of processing waste material, such as sorting, treatment, or [[recycling]]. Unless they are stabilized, landfills may undergo severe shaking or [[soil liquefaction]] of the ground during an [[earthquake]]. Once full, the area over a landfill site may be [[Landfill restoration|reclaimed]] for other uses.

Both active and restored landfill sites can have significant environmental impacts which can persist for many years. These include the release of gases that contribute to climate change and the discharge of liquid leachates containing high concentrations of polluting materials.

==Operations==
[[File:Landfill.jpg|thumb|right|One of several landfills used by [[Dryden, Ontario]], Canada]]
[[File:Garbage dump in Karachi.jpg|thumb|right|Garbage dumped in the middle of a road in [[Karachi]], Pakistan]]

Operators of well-run landfills for non-hazardous waste meet predefined specifications by applying techniques to:<ref>{{Cite web |title=Waste Management. Background information. General objectives of waste policy. |url=https://sustainabledevelopment.un.org/content/documents/dsd/dsd_aofw_ni/ni_pdfs/NationalReports/finland/WASTE.pdf |access-date=10 May 2024 |website=www.sustainabledevelopment.un.org}}</ref>

# confine waste to as small an area as possible
# compact waste to reduce volume<ref name=":1">{{cite web|url=http://www.co.cumberland.nc.us/departments/solid-waste-group/solid-waste-management/ann-street-landfill/how-a-landfill-operates|title=How a Landfill Operates|website=www.co.cumberland.nc.us|access-date=2020-02-22|archive-date=February 27, 2021|archive-url=https://web.archive.org/web/20210227021919/https://www.co.cumberland.nc.us/departments/solid-waste-group/solid-waste-management/ann-street-landfill/how-a-landfill-operates|url-status=dead}}</ref>

They can also cover waste (usually daily) with layers of soil or other types of material such as woodchips and fine particles.

During landfill operations, a [[truck scale|scale or weighbridge]] may weigh waste collection vehicles on arrival and personnel may inspect loads for wastes that do not accord with the landfill's waste-acceptance criteria.<ref name=":1" /> Afterward, the waste collection vehicles use the existing road network on their way to the tipping face or working front, where they unload their contents. After loads are deposited, [[compactor]]s or bulldozers can spread and [[Waste compaction|compact the waste]] on the working face. Before leaving the landfill boundaries, the waste collection vehicles may pass through a wheel-cleaning facility. If necessary, they return to the weighbridge for re-weighing without their load. The weighing process can assemble statistics on the daily incoming waste tonnage, which databases can retain for record keeping. In addition to trucks, some landfills may have equipment to handle railroad containers. The use of "rail-haul" permits landfills to be located at more remote sites, without the problems associated with many truck trips.

Typically, in the working face, the compacted waste is covered with soil or alternative materials daily. Alternative waste-cover materials include chipped wood or other "[[green waste]]",<ref>{{cite web| url= http://www.calrecycle.ca.gov/lgcentral/basics/adcbasic.htm| title= Alternative Daily Cover (ADC)| access-date= September 14, 2012| archive-date= June 5, 2012| archive-url= https://web.archive.org/web/20120605044817/http://www.calrecycle.ca.gov/lgcentral/basics/adcbasic.htm| url-status= dead}}</ref> several sprayed-on foam products, chemically "fixed" bio-solids, and temporary blankets. Blankets can be lifted into place at night and then removed the following day prior to waste placement. The space that is occupied daily by the compacted waste and the cover material is called a daily cell. Waste compaction is critical to extending the life of the landfill. Factors such as waste compressibility, waste-layer thickness and the number of passes of the compactor over the waste affect the waste densities.

== Sanitary landfill life cycle==

[[File:LANDFILL.png|thumb|Sanitary landfill diagram]]

The term ''landfill'' is usually shorthand for a municipal landfill or sanitary landfill. These facilities were first introduced early in the 20th century, but gained wide use in the 1960s and 1970s, in an effort to eliminate open dumps and other "unsanitary" waste disposal practices. The sanitary landfill is an engineered facility that separates and confines waste.  Sanitary landfills are intended as [[bioreactor|biological reactors]] in which microbes will break down complex organic waste into simpler, less toxic compounds over time. These reactors must be designed and operated according to regulatory standards and guidelines covered by the field of [[environmental engineering]].

Aerobic [[decomposition]] is often the first stage by which wastes are broken down in a landfill. This process is followed by four stages of anaerobic degradation. Solid organic material typically decays rapidly as larger organic molecules degrade into smaller molecules. These smaller organic molecules begin to dissolve and move to the liquid phase, followed by [[hydrolysis]] of the organic molecules, and the hydrolyzed compounds then undergo transformation and volatilization as [[carbon dioxide]] (CO<sub>2</sub>) and [[methane]] (CH<sub>4</sub>), with the rest of the waste remaining in solid and liquid phases.

During the early phases, little material volume reaches the [[leachate]] as the biodegradable organic matter of the waste undergoes a rapid decrease in volume. Meanwhile, the leachate's [[chemical oxygen demand]] rises with increasing concentrations of the more recalcitrant compounds compared to the more reactive compounds in the leachate. Successful conversion and stabilization of the waste depends on how well microbial populations function in [[syntrophy]].<ref name="Vallero">{{cite book|title=Municipal Landfill, D. Vallero and G. Blight, pp. 235–249 in Waste: A Handbook for Management|date=2019|editor1-first=T.M.|editor1-last=Letcher|editor2-first=D.A.|editor2-last=Vallero|publisher=Elsevier Academic Press|location=Amsterdam, Netherlands and Boston MA, Print Book|isbn=9780128150603}} 804 pages.</ref>

The life cycle of a municipal landfill undergoes five distinct phases, as follows:<ref>U.S. Environmental Protection Agency (2007) Landfill bioreactor performance: second interim report: outer loop recycling & disposal facility - Louisville, Kentucky, EPA/600/R-07/060</ref><ref name="Vallero"/>

===Initial adjustment (Phase I)===

As the waste is placed in the landfill, the void spaces contain high volumes of molecular oxygen (O<sub>2</sub>). With added and compacted wastes, the O<sub>2</sub> content of the landfill bioreactor strata gradually decreases. Microbial populations grow, density increases. Aerobic biodegradation dominates, i.e. the primary electron acceptor is O<sub>2</sub>.

===Transition (Phase II)===

The O<sub>2</sub> is rapidly degraded by the existing microbial populations. The decreasing O<sub>2</sub> leads to less aerobic and more anaerobic conditions in the layers. The primary electron acceptors during transition are nitrates and sulphates since O<sub>2</sub> is rapidly displaced by CO<sub>2</sub> in the effluent gas.

===Acid formation (Phase III)===

Hydrolysis of the biodegradable fraction of the solid waste begins in the acid formation phase, which leads to rapid accumulation of [[volatile fatty acids]] (VFAs) in the leachate. The increased organic acid content decreases the leachate [[pH]] from approximately 7.5 to 5.6. During this phase, the decomposition intermediate compounds like the VFAs contribute much [[chemical oxygen demand]] (COD). Long-chain volatile organic acids (VOAs) are converted to acetic acid (C<sub>2</sub>H<sub>4</sub>O<sub>2</sub>), CO<sub>2</sub>, and hydrogen gas (H<sub>2</sub>). High concentrations of VFAs increase both the [[biochemical oxygen demand]] (BOD) and VOA concentrations, which initiates H<sub>2</sub> production by fermentative bacteria, which stimulates the growth of H<sub>2</sub>-oxidizing bacteria. The H<sub>2</sub> generation phase is relatively short because it is complete by the end of the acid formation phase. The increase in the biomass of [[acidogenic]] bacteria increases the amount of degradation of the waste material and consuming nutrients. Metals, which are generally more water-soluble at lower pH, may become more mobile during this phase, leading to increasing metal concentrations in the leachate.

===Methane fermentation (Phase IV)===

The acid formation phase intermediary products (e.g., acetic, propionic, and butyric acids) are converted to CH<sub>4</sub> and CO<sub>2</sub> by methanogenic microorganisms. As VFAs are metabolized by the methanogens, the landfill water pH returns to neutrality. The leachate's organic strength, expressed as oxygen demand, decreases at a rapid rate with increases in CH<sub>4</sub> and CO<sub>2</sub> gas production. This is the longest decomposition phase.

===Final maturation and stabilization (Phase V)===

The rate of microbiological activity slows during the last phase of waste decomposition as the supply of nutrients limits the chemical reactions, e.g. as [[bioavailable]] phosphorus becomes increasingly scarce. CH<sub>4</sub> production almost completely disappears, with O<sub>2</sub> and oxidized species gradually reappearing in the gas wells as O<sub>2</sub> permeates downwardly from the troposphere. This transforms the [[oxidation–reduction]] potential (ORP) in the leachate toward oxidative processes. The residual organic materials may incrementally be converted to the gas phase, and as organic matter is composted; i.e. the organic matter is converted to [[humic]]-like compounds.<ref>{{Cite journal|last1=Weitz|first1=Keith|last2=Barlaz|first2=Morton|last3=Ranjithan|first3=Ranji|last4=Brill|first4=Downey|last5=Thorneloe|first5=Susan|last6=Ham|first6=Robert|date=July 1999|title=Life Cycle Management of Municipal Solid Waste|journal=The International Journal of Life Cycle Assessment|language=en|volume=4|issue=4|pages=195–201|doi=10.1007/BF02979496|bibcode=1999IJLCA...4..195W |s2cid=108698198|issn=0948-3349}}</ref>

==Social and environmental impact==
[[Image:Landfill Hawaii.jpg|thumb|right|250px|Landfill operation in Hawaii. The area being filled is a single, well-defined "cell" and a protective [[landfill liner]] is in place (exposed on the left) to prevent contamination by [[leachate]]s migrating downward through the underlying geological formation.]]

Landfills have the potential to cause a number of issues. [[Infrastructure]] disruption, such as damage to access roads by heavy vehicles, may occur. Pollution of local roads and watercourses from wheels on vehicles when they leave the landfill can be significant and can be mitigated by [[wheel washing system]]s. [[Pollution]] of the local [[natural environment|environment]], such as contamination of [[groundwater]] or [[aquifers]] or [[soil contamination]] may occur as well.

=== Leachate ===
{{Main|Leachate}}
When [[precipitation]] falls on open landfills, or when water is released from the breakdown of waste, water percolates through the waste and becomes contaminated with suspended and dissolved material, forming leachate enriched with [[organic matter]], [[heavy metals]], organic [[Contamination|contaminants]], and other contaminants present in the waste.<ref name=":0">{{Cite journal |last1=Kjeldsen |first1=Peter |last2=Barlaz |first2=Morton A. |last3=Rooker |first3=Alix P. |last4=Baun |first4=Anders |last5=Ledin |first5=Anna |last6=Christensen |first6=Thomas H. |date=2002-10-01 |title=Present and Long-Term Composition of MSW Landfill Leachate: A Review |url=https://www.tandfonline.com/doi/abs/10.1080/10643380290813462 |journal=Critical Reviews in Environmental Science and Technology |volume=32 |issue=4 |pages=297–336 |doi=10.1080/10643380290813462 |bibcode=2002CREST..32..297K |issn=1064-3389|url-access=subscription }}</ref><ref>{{Cite journal |last=Vaverková |first=Magdalena Daria |date=2019-10-03 |title=Landfill Impacts on the Environment—Review |journal=Geosciences |language=en |volume=9 |issue=10 |pages=431 |doi=10.3390/geosciences9100431 |doi-access=free |bibcode=2019Geosc...9..431V |issn=2076-3263}}</ref><ref>{{Cite journal |last1=Siddiqua |first1=Ayesha |last2=Hahladakis |first2=John N. |last3=Al-Attiya |first3=Wadha Ahmed K. A. |date=2022-08-01 |title=An overview of the environmental pollution and health effects associated with waste landfilling and open dumping |journal=Environmental Science and Pollution Research |language=en |volume=29 |issue=39 |pages=58514–58536 |doi=10.1007/s11356-022-21578-z |issn=1614-7499 |pmc=9399006 |pmid=35778661|bibcode=2022ESPR...2958514S }}</ref> If this is not contained it can contaminate [[groundwater]]. All modern landfill sites use a combination of impermeable [[Landfill liner|liners]] several metres thick, geologically stable sites, and collection systems to contain and capture this leachate. It can then be treated and evaporated. Once a landfill site is full, it is sealed off to prevent precipitation entering the landfill and formation of new leachate. However, liners have a lifespan, often several hundred years or more, but eventually any landfill liner could leak,<ref>US EPA, "Solid Waste Disposal Facility Criteria; Proposed Rule", Federal Register 53(168):33314–33422, 40 CFR Parts 257 and 258, US EPA, Washington, D.C., August 30 (1988a).</ref> so the ground around landfills must be tested for leachate to prevent pollutants from contaminating groundwater.

The largest problem in sanitary landfills with regards to leachate quality is [[nitrogen]], particularly in the form of [[ammonium]] nitrogen.<ref>{{Cite journal |last1=Berge |first1=Nicole D. |last2=Reinhart |first2=Debra R. |last3=Townsend |first3=Timothy G. |date=2005-07-01 |title=The Fate of Nitrogen in Bioreactor Landfills |url=https://www.tandfonline.com/doi/abs/10.1080/10643380590945003 |journal=Critical Reviews in Environmental Science and Technology |volume=35 |issue=4 |pages=365–399 |doi=10.1080/10643380590945003 |bibcode=2005CREST..35..365B |issn=1064-3389|url-access=subscription }}</ref> Hydrolysis of waste results in the release of carbon species such as [[bicarbonate]] and [[acetic acid]] as well as the release of ammonium. The anaerobic environment present in landfills does not allow for coupled [[nitrification]]-[[denitrification]], the typical nitrogen removal pathway in soils, which can lead to an accumulation of ammonium in the leachate and concentrations upwards of several thousand milligrams per liter.<ref name=":0" />

=== Decomposition gases ===
{{Main|Landfill gas}}
[[Anaerobic digestion]] of organic waste by microbes results in the generation of [[landfill gas|decomposition gases]], particularly of CO<sub>2</sub> and CH<sub>4</sub>. The fraction of gas constituents depends foremost on available oxygen, and further varies depending on landfill age, waste type, moisture content, and other factors. On average, about half of the volumetric concentration of landfill gas is CH<sub>4</sub>, and slightly less than half is CO<sub>2</sub>; the ratio shifts towards more CO<sub>2</sub> upon increasing aerobic degradation.<ref>{{Cite journal |last1=Manheim |first1=Derek C. |last2=Yeşiller |first2=Nazli |last3=Hanson |first3=James L. |date=2021-10-01 |title=Gas Emissions from Municipal Solid Waste Landfills: A Comprehensive Review and Analysis of Global Data |url=https://link.springer.com/article/10.1007/s41745-021-00234-4 |journal=Journal of the Indian Institute of Science |language=en |volume=101 |issue=4 |pages=625–657 |doi=10.1007/s41745-021-00234-4 |issn=0019-4964|url-access=subscription }}</ref> The average landfill gas further contains about 5% molecular nitrogen (N<sub>2</sub>), less than 1% [[hydrogen sulfide]] (H<sub>2</sub>S), and low concentrations of non-methane organic compounds (NMOC), about 2700 parts per million by volume.<ref name="Themelis, Nickolas J. 2007" /> The maximum amount of landfill gas produced can be illustrated by a simplified net reaction of diethyl oxalate that accounts for these simultaneous reactions:<ref name="Themelis, Nickolas J. 2007">Themelis, Nickolas J., and Priscilla A. Ulloa. "Methane generation in landfills." Renewable Energy 32.7 (2007), 1243–1257</ref>

4 C<sub>6</sub>H<sub>10</sub>O<sub>4</sub> + 6 H<sub>2</sub>O → 13 CH<sub>4</sub> + 11 CO<sub>2</sub>[[File:Χωματερή Μαυροράχης (ΧΥΤΑ Μακεδονίας).jpg|thumb|Waste disposal in Athens, Greece]]
Landfill gases can seep out of the landfill and into the surrounding air and soil.  This makes landfills a significant source of [[Greenhouse gas|greenhouse gases]] in the form of CO<sub>2</sub> and particularly CH<sub>4</sub>, with landfills being the 3<sup>rd</sup> largest emitter of CH<sub>4</sub> worldwide<ref>United Nations Environment Programme and Climate and Clean Air Coalition (2021). ''Global Methane Assesment: Benefits and Costs of Mitigating Methane Emissions.'' Nairobi: United Nations Environment Programme</ref><ref>EEA. ''EEA greenhouse gases — data viewer | European Environment Agency’s home page''. <nowiki>https://www.eea.europa.eu/en/analysis/maps-and-charts/greenhouse-gases-viewer-data-viewers</nowiki> (accessed 2025-03-25).</ref> and CH<sub>4</sub> having a [[global warming potential]] of 29.8 ± 11 relative to CO<sub>2</sub> over a period of 100 years, and 82.5 ± 25.8 over a period of 20 years.<ref>{{Citation |title=The Earth's Energy Budget, Climate Feedbacks and Climate Sensitivity |date=2023 |work=Climate Change 2021 – The Physical Science Basis: Working Group I Contribution to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change |pages=923–1054 |editor-last=Intergovernmental Panel on Climate Change (IPCC) |url=https://www.cambridge.org/core/books/climate-change-2021-the-physical-science-basis/earths-energy-budget-climate-feedbacks-and-climate-sensitivity/AE57C97E588FF3060C7C7E47DD4F3C6E |access-date=2025-04-11 |place=Cambridge |publisher=Cambridge University Press |doi=10.1017/9781009157896.009 |isbn=978-1-009-15788-9}}</ref> Properly managed landfills ensure collection and usage of gases. This can range from simple [[Gas flare|flaring]] to get rid of the gas to [[landfill gas utilization]] for [[electricity generation]].<ref>{{Cite journal |last1=Qin |first1=W. |last2=Egolfopoulos |first2=F. N. |last3=Tsotsis |first3=T. T. |date=2001-03-15 |title=Fundamental and environmental aspects of landfill gas utilization for power generation |url=https://linkinghub.elsevier.com/retrieve/pii/S1385894700003661 |journal=Chemical Engineering Journal |series=FRONTIERS IN CHEMICAL REACTION ENGINEERING |volume=82 |issue=1 |pages=157–172 |doi=10.1016/S1385-8947(00)00366-1 |bibcode=2001ChEnJ..82..157Q |issn=1385-8947|url-access=subscription }}</ref> Monitoring landfill gas alerts workers to the presence of a build-up of gases to a harmful level. In some countries, landfill gas recovery is extensive; in the United States, for example, more than 850 landfills have active landfill gas recovery systems.<ref>{{cite journal |last1=Powell |first1=Jon T. |last2=Townsend |first2=Timothy G. |last3=Zimmerman |first3=Julie B. |date=September 21, 2015 |title=Estimates of solid waste disposal rates and reduction targets for landfill gas emissions |journal=Nature Climate Change |volume=6 |issue=2 |pages=162–165 |doi=10.1038/nclimate2804}}</ref> 

=== Other nuisances ===
[[File:A herd of 40 wild elephants at Ampara in east Sri Lanka is totally dependent on garbage from tractors DSC8792.jpg|thumb|A group of wild elephants interacting with a trash dump in Sri Lanka]]
Other potential issues of landfills include [[wildlife]] disruption due to occupation of habitat<ref>{{cite web|url=https://myzerowaste.com/2009/01/how-does-landfill-and-litter-affect-our-wildlife/|title=How does landfill and litter affect our wildlife?|date=2009-01-30|website=MY ZERO WASTE|language=en-US|access-date=2020-02-22}}</ref> and animal health disruption caused by consuming waste from landfills,<ref>{{cite web|url=https://www.cdenviro.com/news/2017/october/landfills-are-ruining-lives|title=Landfills are Ruining Lives|website=www.cdenviro.com|access-date=2020-02-22}}</ref> dust, odor, [[noise pollution]],<ref>Danthurebandara, M.; Van Passel, S.; Nelen, D.; Tielemans, Y.; Van Acker, K. Environmental and Socio-Economic Impacts of Landfills. In ''Linnaeus ECO-tech''; 2012.</ref> and reduced local property  values.<ref>{{Cite journal |last1=Reichert |first1=Alan |last2=Small |first2=Michael |last3=Mohanty |first3=Sunil |date=1992-01-01 |title=The Impact of Landfills on Residential Property Values |url=https://www.tandfonline.com/doi/abs/10.1080/10835547.1992.12090677 |journal=Journal of Real Estate Research |volume=7 |issue=3 |pages=297–314 |doi=10.1080/10835547.1992.12090677 |issn=0896-5803|url-access=subscription }}</ref> Poorly run landfills may further become nuisances because of [[Vector (epidemiology)|vectors]] such as rats and flies which can spread [[Infection|infectious diseases]]. The occurrence of such vectors can be mitigated through the use of [[daily cover]].<ref>{{Cite journal |last1=Qasim |first1=Muhammad |last2=Xiao |first2=Huamei |last3=He |first3=Kang |last4=Noman |first4=Ali |last5=Liu |first5=Feiling |last6=Chen |first6=Meng-Yao |last7=Hussain |first7=Dilbar |last8=Jamal |first8=Zakia A. |last9=Li |first9=Fei |date=2020-11-01 |title=Impact of landfill garbage on insect ecology and human health |url=https://linkinghub.elsevier.com/retrieve/pii/S0001706X20310214 |journal=Acta Tropica |volume=211 |pages=105630 |doi=10.1016/j.actatropica.2020.105630 |pmid=32673623 |issn=0001-706X|url-access=subscription }}</ref>

==Landfill aftercare==
[[File:Faria 000102 153913 493502 4578 (35502216424).jpg|thumb|[[Solar arrays]] on a full landfill in [[Rehoboth, Massachusetts|Rehoboth, MA]]]]
Once a landfill is filled, a top liner or cap is placed on top of the landfill to prevent further inflow of precipitation. The landfill subsequently enters the “aftercare” stage.<ref>{{Cite journal |last1=Laner |first1=David |last2=Crest |first2=Marion |last3=Scharff |first3=Heijo |last4=Morris |first4=Jeremy W. F. |last5=Barlaz |first5=Morton A. |date=2012-03-01 |title=A review of approaches for the long-term management of municipal solid waste landfills |url=https://linkinghub.elsevier.com/retrieve/pii/S0956053X11005344 |journal=Waste Management |volume=32 |issue=3 |pages=498–512 |doi=10.1016/j.wasman.2011.11.010 |pmid=22188873 |bibcode=2012WaMan..32..498L |issn=0956-053X|url-access=subscription }}</ref> During aftercare, environmental impacts are minimized through the (re)placement of liners, capture of greenhouse gases, and treatment of contaminant-rich leachates. Estimated duration of aftercare has been estimated between several decades up to eternity with an estimated aftercare cost of more than 20 million euros per landfill in the Netherlands.<ref name=":2">{{Cite journal |last=Scharff |first=Heijo |date=2014-11-01 |title=Landfill reduction experience in The Netherlands |url=https://linkinghub.elsevier.com/retrieve/pii/S0956053X14002451 |journal=Waste Management |volume=34 |issue=11 |pages=2218–2224 |doi=10.1016/j.wasman.2014.05.019 |pmid=24999096 |bibcode=2014WaMan..34.2218S |issn=0956-053X|url-access=subscription }}</ref>

== Sustainability ==

=== Bioreactor landfill ===
{{Main|Bioreactor landfill}}
The practice of sanitary landfilling poses challenges with regards to [[sustainability]]. Once the lifetime of the landfill is completed, and it enters its aftercare period, the typical practice of sealing the waste with liners restricts contaminants within the landfill and prevents the waste from being subdued to environmental factors. The waste’s potential to pollute the environment is thus maintained within the landfill, and the replacement of liners and treatment of leachate is an indefinite requirement. Certain countries, such as the Netherlands, consequently consider the necessity of long-term aftercare, up-to eternal.<ref name=":2" /> An alternative strategy is to operate the landfill as a bioreactor, which stimulates the degradation process by either aerating the waste<ref>{{Cite journal |last1=Ritzkowski |first1=M. |last2=Stegmann |first2=R. |date=2012-07-01 |title=Landfill aeration worldwide: Concepts, indications and findings |url=https://linkinghub.elsevier.com/retrieve/pii/S0956053X12000803 |journal=Waste Management |volume=32 |issue=7 |pages=1411–1419 |doi=10.1016/j.wasman.2012.02.020 |pmid=22459512 |bibcode=2012WaMan..32.1411R |issn=0956-053X|url-access=subscription }}</ref> or recirculating leachate through the waste body.<ref>{{Cite journal |last1=Bilgili |first1=M. Sinan |last2=Demir |first2=Ahmet |last3=Özkaya |first3=Bestamin |date=2007-05-08 |title=Influence of leachate recirculation on aerobic and anaerobic decomposition of solid wastes |url=https://linkinghub.elsevier.com/retrieve/pii/S0304389406010533 |journal=Journal of Hazardous Materials |volume=143 |issue=1 |pages=177–183 |doi=10.1016/j.jhazmat.2006.09.012 |bibcode=2007JHzM..143..177B |issn=0304-3894|url-access=subscription }}</ref> Bioreactor landfills stimulate the removal of contaminants to a point where contaminant emissions no longer threaten the environment. At this point, placement of liners and treatment of gas and leachate is no longer required, significantly limiting costs and reducing the impact on future generations.<ref name=":3">{{Cite journal |last1=Berge |first1=Nicole D. |last2=Reinhart |first2=Debra R. |last3=Batarseh |first3=Eyad S. |date=2009-05-01 |title=An assessment of bioreactor landfill costs and benefits |url=https://linkinghub.elsevier.com/retrieve/pii/S0956053X08004285 |journal=Waste Management |series=First international conference on environmental management, engineering, planning and economics |volume=29 |issue=5 |pages=1558–1567 |doi=10.1016/j.wasman.2008.12.010 |bibcode=2009WaMan..29.1558B |issn=0956-053X|url-access=subscription }}</ref> Additional benefits include a stimulated gas production during the active treatment period, allowing for a more efficient potential for energy generation during a shorter timeframe.<ref name=":3" />

=== Material reclamation ===
{{Main|Landfill mining}}
One can treat landfills as a viable and abundant source of materials and [[Waste-to-energy|energy]]. In the developing world, [[waste picker]]s often scavenge for still-usable materials. In [[commerce|commercial]] contexts, companies have also discovered landfill sites, and many{{quantify|date=August 2019}} have begun harvesting materials and energy.<ref>{{Cite web |title=Sinologie Spectrum |url=https://www.chinalize.nl/2008/node/15 |url-status=dead |archiveurl=https://web.archive.org/web/20091208021902/http://www.chinalize.nl/2008/node/15 |archivedate=December 8, 2009 |website=www.chinalize.nl}}</ref> Well-known examples include gas-recovery facilities.<ref>{{cite web |title=Commercial exploitation of gas from landfills |url=http://www.treehugger.com/files/2008/05/landfill-gas-energy-biogas.php |url-status=dead |archive-url=https://web.archive.org/web/20111024211038/http://www.treehugger.com/files/2008/05/landfill-gas-energy-biogas.php |archive-date=October 24, 2011 |access-date=November 28, 2009}}</ref> Other commercial facilities include waste [[incinerator]]s which have built-in material recovery. This material recovery is possible through the use of [[filtration|filters]] ([[Electrofiltration|electro filter]], [[Activated carbon|active-carbon]] and potassium filter, quench, HCl-washer, SO<sub>2</sub>-washer, [[bottom ash]]-grating, etc.).

=== Landfill restoration ===
{{Main|Landfill restoration}}
Following placement of the cap and closure of the landfill, the area is oftentimes re-purposed. Popular alternative land-uses include recreational purposes (e.g. mountain bike courses<ref>{{Cite web |title=MTB route Braambergen |url=https://www.visitflevoland.nl/en/routes/2196754643/mtb-route-braambergen |access-date=2025-04-11 |website=www.visitflevoland.nl |language=en}}</ref>), the placement of solar panels to create solar array farms,<ref>Sampson, G. (2009). Solar power installations on closed landfills: Technical and regulatory considerations. ''Remediation and Technology Innovation Washington, DC''.</ref> parks,<ref>{{Cite journal |last1=Simis |first1=Mazifah |last2=Awang |first2=Azahan |last3=Arifin |first3=Kadir |date=2016-06-23 |title=From Ex-landfill to Public Park: Impact on Local Community's Quality of Life and Living Environment |url=https://linkinghub.elsevier.com/retrieve/pii/S1877042816302312 |journal=Procedia - Social and Behavioral Sciences |series=ASEAN-Turkey ASLI QoL2015: AicQoL2015Jakarta, Indonesia, 25–27 April 2015 |volume=222 |pages=763–771 |doi=10.1016/j.sbspro.2016.05.157 |issn=1877-0428|doi-access=free }}</ref> or living areas.

==Regional practice==
[[File:Landfill face.JPG|thumb|right|A landfill in Perth, Western Australia]]
[[File:South East New Territories Landfill 2.jpg|thumb|right|South East New Territories Landfill, [[Hong Kong]]]]

===Canada===
Landfills in Canada are regulated by provincial environmental agencies and environmental protection legislation.<ref>{{Cite web|url=http://www.ontario.ca/page/ministry-environment-conservation-parks|title=Ministry of the Environment, Conservation and Parks &#124; ontario.ca|website=www.ontario.ca}}</ref>
Older facilities tend to fall under current standards and are monitored for [[leachate|leaching]].<ref>{{Cite web|url=http://www.ecoissues.ca/index.php/Aging_Landfills:_Ontario%E2%80%99s_Forgotten_Polluters|title=Aging Landfills: Ontario's Forgotten Polluterswork=Eco Issues|date=September 28, 2010|archive-url=https://web.archive.org/web/20100928022645/http://www.ecoissues.ca/index.php/Aging_Landfills:_Ontario%E2%80%99s_Forgotten_Polluters|archive-date=September 28, 2010}}</ref> Some former locations have been converted to parkland.

===European Union===
[[File:Rusko Landfill Oulu 20070318 02.jpg|thumb|The Rusko landfill in [[Oulu|Oulu, Finland]]]]
In the European Union, individual states are obliged to enact legislation to comply with the requirements and obligations of the European [[Landfill Directive]].

The majority of EU member states have laws banning or severely restricting the disposal of household trash via landfills.<ref>{{Cite web|url=https://www.cewep.eu/landfill-taxes-and-restrictions/|title=CEWEP - The Confederation of European Waste-to-Energy Plants}}</ref>

=== India ===
Landfilling is currently the major method of municipal waste disposal in India. India also has Asia's largest dumping ground in Deonar, Mumbai.<ref name="autogenerated1">{{cite web|url=https://swachhindia.ndtv.com/year-ender-2018-waste-management-landfill-how-indian-cities-dealt-with-landfill-crisis-29247/|title=Fighting Mountains Of Garbage: Here Is How Indian Cities Dealt With Landfill Crisis In 2018 {{!}} Swachh Year Ender|date=2018-12-31|website=NDTV|language=en-US|access-date=2020-02-21}}</ref> However, issues frequently arise due to the alarming growth rate of landfills and poor management by authorities.<ref>{{cite web|url=https://www.sciencealert.com/a-growing-mountain-of-rubbish-in-india-will-soon-require-aircraft-warning-lights|title=India's 'Mount Everest' of Trash Is Growing So Fast, It Needs Aircraft Warning Lights|last=Cassella|first=Carly|website=ScienceAlert|date=June 5, 2019 |language=en-gb|access-date=2020-02-21}}</ref> On and under surface fires have been commonly seen in the Indian landfills over the last few years.<ref name="autogenerated1"/>

=== United Kingdom ===
{{Main|Landfills in the United Kingdom}}

Landfilling practices in the UK have had to change in recent years to meet the challenges of the European [[Landfill Directive]]. The UK now imposes landfill tax upon [[biodegradable waste]] which is put into landfills. In addition to this the [[Landfill Allowance Trading Scheme]] has been established for local authorities to trade landfill quotas in England. A different system operates in [[Wales]] where authorities cannot 'trade' amongst themselves, but have allowances known as the Landfill Allowance Scheme.

===United States===
{{Main|Landfills in the United States}}
U.S. landfills are regulated by each state's environmental agency, which establishes minimum guidelines; however, none of these standards may fall below those set by the [[United States Environmental Protection Agency]] (EPA).<ref>Horinko, Marianne, Cathryn Courtin. [http://www.epaalumni.org/hcp/rcra.pdf "Waste Management: A Half Century of Progress."] EPA Alumni Association. March 2016.</ref>

Permitting a landfill generally takes between five and seven years, costs millions of dollars and requires rigorous siting, engineering and environmental studies and demonstrations to ensure local environmental and safety concerns are satisfied.<ref>{{cite web|url=http://beginwiththebin.org/innovation/modern-landfills|title=Modern landfills|access-date=February 21, 2015|url-status=dead|archive-url=https://web.archive.org/web/20150222005007/http://beginwiththebin.org/innovation/modern-landfills|archive-date=February 22, 2015}}</ref>

== Types ==
* [[Municipal solid waste]]: takes in household waste and nonhazardous material. Included in this type of landfill is a [[Bioreactor landfill|Bioreactor Landfill]] that specifically degrades organic material.
* [[Industrial waste]]: for commercial and industrial waste. Other related landfills include Construction and Demolition Debris Landfills and Coal Combustion Residual Landfills.
* [[Hazardous waste site|Hazardous waste]]<ref>{{cite web|url=http://www.epa.gov/landfills/basic-information-about-landfills#whattypes|title=Basic Information about Landfills|last=EPA, OSWER, ORCR|first=US|website=www.epa.gov|date=March 24, 2016|access-date=March 14, 2017}}</ref> or [[Polychlorinated biphenyl|PCB waste]]:<ref>{{cite web|url=http://www.epa.gov/pcbs/disposal-and-storage-polychlorinated-biphenyl-pcb-waste|title=Disposal and Storage of Polychlorinated Biphenyl (PCB) Waste|date=August 19, 2015|publisher=[[United States Environmental Protection Agency]]|access-date=May 10, 2017}}</ref> Polychlorinated Biphenyl (PCB) landfills that are monitored in the United States by the [[Toxic Substances Control Act of 1976]] (TSCA).

==Microbial topics==
The status of a landfill's microbial community may determine its digestive efficiency.<ref>{{cite journal|last1=Gomez|first1=A.M.|last2=Yannarell|first2=A.C.|last3=Sims|first3=G.K.|last4=Cadavid-Resterpoa|first4=G.|last5=Herrera|first5=C.X.M.|title=Characterization of bacterial diversity at different depths in the Moravia Hill Landfill site at Medellín, Colombia|journal=Soil Biology and Biochemistry|year=2011|volume=43|pages=1275–1284|doi=10.1016/j.soilbio.2011.02.018|issue=6|bibcode=2011SBiBi..43.1275G }}</ref>

Bacteria that digest plastic have been found in landfills.<ref>{{cite journal|url=http://www.nature.com/news/2011/110328/full/news.2011.191.html|title=Marine microbes digest plastic|author=Gwyneth Dickey Zaikab|journal=Nature|date=March 2011|doi=10.1038/news.2011.191|doi-access=free|url-access=subscription}}</ref>

==Alternatives==
{{See also|List of solid waste treatment technologies}}

In addition to [[waste reduction]] and [[recycling]] strategies, there are various alternatives to landfills, including [[waste-to-energy]] incineration, [[anaerobic digestion]], [[composting]], [[mechanical biological treatment]], [[pyrolysis]] and [[plasma arc gasification]]. Depending on local economics and incentives, these can be made more financially attractive than landfills.

The goal of the [[zero waste]] concept is to minimize landfill volume.<ref name="eap">{{cite journal |last1=Qi |first1=Shiyue |last2=Chen |first2=Ying |last3=Wang |first3=Xuexue |last4=Yang |first4=Yang |last5=Teng |first5=Jingjie |last6=Wang |first6=Yongming |date=March 2024 |title=Exploration and practice of "zero-waste city" in China |journal=Circular Economy |volume=3 |issue=1 |doi=10.1016/j.cec.2024.100079 |doi-access=free }}</ref>

==Restrictions==

Countries including [[Germany]], [[Austria]], [[Sweden]],<ref>{{cite web|url=http://rkrattsbaser.gov.se/sfst?bet=2001:512|title=Regeringskansliets rättsdatabaser|website=rkrattsbaser.gov.se|access-date=2019-05-09|language=sv}}</ref> [[Denmark]], [[Belgium]], the [[Netherlands]], and [[Switzerland]], have banned the disposal of untreated waste in landfills.<ref>{{Cite web |date=2024-12-17 |title=Diversion of waste from landfill in Europe |url=https://www.eea.europa.eu/en/analysis/indicators/diversion-of-waste-from-landfill |access-date=2025-05-10 |website=www.eea.europa.eu |language=en}}</ref> In these countries, only certain hazardous wastes, [[fly ash]]es from [[incineration]] or the stabilized output of [[mechanical biological treatment]] plants may still be deposited.{{citation needed|date=September 2018}}

==See also==
{{Portal|Environment|Ecology}}
{{div col|colwidth=30em}}
* [[Bioreactor landfill]]
* [[Daily cover]]
* [[Fly-tipping]]
* [[Hydrologic Evaluation of Landfill Performance]] (HELP) model
* [[Land reclamation]]
* [[Landfarming]]
* [[Landfill diversion]]
* [[Landfill restoration]]
* [[Landfill tax]]
* [[Marine debris]]
* [[Midden]]
* [[Milorganite]]
* [[National Waste & Recycling Association]]
* [[NIMBY]]
* [[Open dump]]
* [[Recycling rates by country]]
* [[Sludge]]
{{div col end}}

==Notes==
{{Notelist}}

==References==
{{Reflist}}

==Further reading==
* {{cite web | title= Modern landfills | url= http://beginwiththebin.org/innovation/modern-landfills | access-date= February 21, 2015 | url-status= dead | archive-url= https://web.archive.org/web/20150222005007/http://beginwiththebin.org/innovation/modern-landfills | archive-date= February 22, 2015 | df= mdy-all }}
* {{cite web | title= Council Directive 1999/31/EC of 26 April 1999, on the landfill of waste | url= http://eur-lex.europa.eu/pri/en/oj/dat/1999/l_182/l_18219990716en00010019.pdf | access-date= August 29, 2005 | archive-date= July 5, 2010 | archive-url= https://web.archive.org/web/20100705130150/http://eur-lex.europa.eu/pri/en/oj/dat/1999/l_182/l_18219990716en00010019.pdf | url-status= dead | df= mdy-all }}
* {{cite web | title=The Landfill Operation Management Advisor Web Based Expert System | url=http://loma.civil.duth.gr | access-date=August 29, 2005 | url-status=dead | archive-url=https://web.archive.org/web/20051030021240/http://loma.civil.duth.gr/ | archive-date=October 30, 2005 | df=mdy-all }}
* {{cite web | author= H. Lanier Hickman Jr. and Richard W. Eldredge | title= Part 3: The Sanitary Landfill | work= A Brief History of Solid Waste Management in the US During the Last 50 Years | url= http://www.forester.net/msw_0001_history.html | access-date= August 29, 2005 | archive-url= https://web.archive.org/web/20051123103812/http://www.forester.net/msw_0001_history.html | archive-date= November 23, 2005 | url-status= usurped }}
* Daniel A. Vallero, ''Environmental Biotechnology: A Biosystems Approach''. 2nd Edition. Academic Press, Amsterdam, Netherlands and Boston MA, Print Book {{ISBN|9780124077768}}; eBook {{ISBN|9780124078970}}. 2015.

==External links==
{{Wikiquote}}
{{Wiktionary|landfill}}
{{Commons category|Landfills}}
* [http://www.wasterecycling.org US National Waste & Recycling Association]
* [http://www.swana.org Solid Waste Association of North America]
* [https://waste-management-world.com/a/a-compact-guide-to-landfill-operation-machinery-management-and-misconceptions A Compact Guide to Landfill Operation: Machinery, Management and Misconceptions]

{{Waste}}
{{Authority control}}

[[Category:Landfill| ]]
[[Category:Waste management]]