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83-440: It operates a leachate collection system and an on-site leachate treatment plant. Green Lane also has an extensive landfill gas collection system. This gas is roughly 50 percent methane and 50 percent carbon dioxide , along with traces of other gases. The gas is collected and directed to the flaring system that allows for release into the air. As Toronto ’s last remaining landfill site, Keele Valley , neared capacity during

166-595: A 2012 survey performed in New York State, all surveyed double-lined landfill cells had leakage rates of less than 500 liters per hectare per day. Average leakage rates were much lower than for landfills built according to older standards before 1992. When water percolates through waste, it promotes and assists the process of decomposition by bacteria and fungi . These processes in turn release by-products of decomposition and rapidly use up any available oxygen, creating an anoxic environment. In actively decomposing waste,

249-426: A barrier between mobile polluting substances released from wastes and the groundwater. In the closing of landfills, geomembranes are used to provide a low-permeability cover barrier to prevent the intrusion of rain water. Geosynthetic clay liners (GCLs) are fabricated by distributing sodium bentonite in a uniform thickness between woven and non-woven geotextiles. Sodium bentonite has a low permeability, which makes GCLs

332-432: A coarser gradation in the direction of the seepage than the soil to be protected. As liquid enters the landfill cell, it moves down the filter, passes through the pipe network, and rests in the sump. As collection systems are planned, the number, location, and size of the sumps are vital to an efficient operation. When designing sumps, the amount of leachate and liquid expected is the foremost concern. Areas in which rainfall

415-431: A collection device and as a means for isolating leachate within the fill to protect the soil and groundwater below. The chief concern is the ability of a liner to maintain integrity and impermeability over the life of the landfill. Subsurface water monitoring, leachate collection, and clay liners are commonly included in the design and construction of a waste landfill. To effectively serve the purpose of containing leachate in

498-415: A combination of impermeable 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 ingress and new leachate formation. However, liners must have a lifespan, be it several hundred years or more. Eventually, any landfill liner could leak, so

581-400: A healthy operation. Sump pumps can function with preset phase times. If the flow is not predictable, a predetermined leachate height level can automatically switch the system on. Other conditions for sump planning are maintenance and pump drawdown . Collection pipes typically convey the leachate by gravity to one or more sumps, depending upon the size of the area drained. Leachate collected in

664-711: A landfill, a liner system must possess a number of physical properties. The liner must have high tensile strength, flexibility, and elongation without failure. It is also important that the liner resist abrasion, puncture, and chemical degradation by leachate. Lastly, the liner must withstand temperature variation, must resist UV light (which leads most liners to be black), must be easily installed, and must be economical. There are several types of liners used in leachate control and collection. These types include geomembranes , geosynthetic clay liners, geotextiles , geogrids , geonets , and geocomposites . Each style of liner has specific uses and abilities. Geomembranes are used to provide

747-733: A number of cases where this policy was seen to be failing, and an exposee in The Sunday Times of serious environmental damage being caused by inappropriate disposal of industrial wastes, both policy and the law were changed. The Deposit of Poisonous Wastes Act 1972 , together with The 1974 Local Government Act , made local government responsible for waste disposal and for the enforcement of environmental standards regarding waste disposal. Proposed landfill locations also had to be justified not only by geography but also scientifically. Many European countries decided to select landfill sites in groundwater-free clay geological conditions or to require that

830-412: A stabilised and inactive site can become re-activated and restart significant gas production and exhibit significant changes in finished ground levels. One method of leachate management that was more common in uncontained sites was leachate re-circulation, in which leachate was collected and re-injected into the waste mass. This process greatly accelerated decomposition and therefore gas production and had

913-657: A suitable alternative to clay liners in a composite liner system. Geotextiles are used as separation between two different types of soils to prevent contamination of the lower layer by the upper layer. Geotextiles also act as a cushion to protect synthetic layers against puncture from underlying and overlaying rocks. Geogrids are structural synthetic materials used in slope veneer stability to create stability for cover soils over synthetic liners or as soil reinforcement in steep slopes. Geonets are synthetic drainage materials that are often used in lieu of sand and gravel. Radz can take 12 in (30 cm) of drainage sand, thus increasing

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996-476: A treatment system with only minor membrane use is the Nantmel Landfill Site . All membranes are porous to a limited extent so that, over time, low volumes of leachate will cross the membrane. The design of landfill membranes is at such low volumes that they should never have a measurable adverse impact on the quality of the receiving groundwater. A more significant risk may be the failure or abandonment of

1079-440: A viable and abundant source of materials and energy . In the developing world, waste pickers often scavenge for still-usable materials. In commercial contexts, companies have also discovered landfill sites, and many have begun harvesting materials and energy. Well-known examples include gas-recovery facilities. Other commercial facilities include waste incinerators which have built-in material recovery. This material recovery

1162-754: A vote in February 2006 by the Michigan House of Representatives to ban out-of-state garbage from being shipped to the state from Ontario and other U.S. states, as it also required approval by the US federal government before it could be enforced by Michigan. In May 2006, the Michigan Carleton Farms garbage dump under contract with the city of Toronto announced it would not be accepting waste sludge as of August 1, 2006, but would continue to receive household waste. In September 2006, Toronto City Council agreed to purchase

1245-551: Is CO 2 . The gas also contains about 5% molecular nitrogen (N 2 ), less than 1% hydrogen sulfide (H 2 S), and a low concentration of non-methane organic compounds (NMOC) , about 2700 ppmv . Landfill gases can seep out of the landfill and into the surrounding air and soil. Methane is a greenhouse gas , and is flammable and potentially explosive at certain concentrations, which makes it perfect for burning to generate electricity cleanly. Since decomposing plant matter and food waste only release carbon that has been captured from

1328-932: Is acidic and offensive and may be very pervasive because of hydrogen-, nitrogen- and sulfur-rich organic species such as mercaptans . In a landfill that receives a mixture of municipal, commercial, and mixed industrial waste but excludes significant amounts of concentrated chemical waste, landfill leachate may be characterized as a water-based solution of four groups of contaminants: dissolved organic matter (alcohols, acids, aldehydes, short chain sugars, etc.), inorganic macro components (common cations and anions including sulfate, chloride, iron, aluminium, zinc and ammonia), heavy metals (Pb, Ni, Cu, Hg), and xenobiotic organic compounds such as halogenated organics, ( PCBs , dioxins , etc.). A number of complex organic contaminants have also been detected in landfill leachates. Samples from raw and treated landfill leachate yielded 58 complex organic contaminants including 2-OH-benzothiazole in 84% of

1411-477: Is associated with stockpiled coal and with waste materials from metal ore mining and other rock extraction processes, especially those in which sulfide containing materials are exposed to air producing sulfuric acid , often with elevated metal concentrations. In the context of civil engineering (more specifically reinforced concrete design), leachate refers to the effluent of pavement wash-off (that may include melting snow and ice with salt) that permeates through

1494-410: Is higher than average typically have larger sumps. A further criterion for sump planning is accounting for the pump capacity. The relationship of pump capacity and sump size is inverse. If the pump capacity is low, the volume of the sump should be larger than average. It is critical for the volume of the sump to be able to store the expected leachate between pumping cycles. This relationship helps maintain

1577-403: Is less predictable, the pump may be automatically switched on when the leachate reaches a predetermined level. More modern landfills in the developed world have some form of membrane separating the waste from the surrounding ground, and in such sites there is often a leachate collection series of pipes laid on the membrane to convey the leachate to a collection or treatment location. An example of

1660-548: Is now mandatory within the United States , Australia and the European Union except where the waste is deemed inert. In addition, most toxic and difficult materials are now specifically excluded from landfilling. However, despite much stricter statutory controls, leachates from modern sites are often found to contain a range of contaminants stemming from illegal activity or legally discarded household and domestic products. In

1743-446: Is often the highest pH allowed in sewer discharges. Many older leachate streams also contained a variety of synthetic organic species and their decomposition products, some of which had the potential to be acutely damaging to the environment. The risks from waste leachate are due to its high organic contaminant concentrations and high concentration of ammonia . Pathogenic microorganisms that might be present in it are often cited as

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1826-548: Is possible through the use of filters ( electro filter , active-carbon and potassium filter, quench, HCl-washer, SO 2 -washer, bottom ash -grating, etc.). 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

1909-667: Is rapidly displaced by CO 2 in the effluent gas. 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 2 H 4 O 2 ), CO 2 , and hydrogen gas (H 2 ). High concentrations of VFAs increase both

1992-445: Is rarely of sufficient quality to be released to the environment and may be tankered or piped to a local sewage treatment facility; the decision depends on the age of the landfill and on the limit of water quality that must be achieved after treatment. With high conductivity, leachate is hard to treat with biological treatment or chemical treatment. Treatment with reverse osmosis is also limited, resulting in low recoveries and fouling of

2075-497: Is removed for treatment or disposal. The pipes also serve as drains within the drainage layer to minimize the mounding of leachate in the layer. These pipes are designed with cuts that are inclined to 120 degrees, preventing entry of solid particles. The filter layer is used above the drainage layer in leachate collection. Two types of filters are typically used in engineering practices: granular and geotextile. Granular filters consist of one or more soil layers or multiple layers having

2158-526: Is that leachates are a difficult-to-treat waste stream. However, within ageing municipal solid waste landfills, this may not be a problem as the pH returns close to neutral after the initial stage of acidogenic leachate decomposition. Many sewer undertakers limit maximum ammoniacal nitrogen concentration in their sewers to 250 mg/L to protect sewer maintenance workers, as the WHO's maximum occupational safety limit would be exceeded at above pH 9 to 10, which

2241-518: Is the first stage by which wastes are broken down in a landfill. These are followed by four stages of anaerobic degradation. Usually, solid organic material in solid phase 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 these organic molecules, and the hydrolyzed compounds then undergo transformation and volatilization as carbon dioxide (CO 2 ) and methane (CH 4 ), with rest of

2324-403: Is the longest decomposition phase. 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 4 production almost completely disappears, with O 2 and oxidized species gradually reappearing in the gas wells as O 2 permeates downwardly from

2407-628: 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 archeology as middens ). 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

2490-679: 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. 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

2573-576: The United States Environmental Protection Agency (EPA). 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. The status of a landfill's microbial community may determine its digestive efficiency. Bacteria that digest plastic have been found in landfills. One can treat landfills as

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2656-574: The biochemical oxygen demand (BOD) and VOA concentrations, which initiates H 2 production by fermentative bacteria, which stimulates the growth of H 2 -oxidizing bacteria. The H 2 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

2739-792: The landfill gas utilization and generation of electricity . Landfill gas monitoring 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. A Solar landfill is a repurposed used landfill that is converted to a solar array solar farm . Landfills in Canada are regulated by provincial environmental agencies and environmental protection legislation. Older facilities tend to fall under current standards and are monitored for leaching . Some former locations have been converted to parkland. In

2822-643: The 1990s, it was found that no other municipality in Southern Ontario was willing to accept the garbage, but there was also no political support for a change to incineration . A deal was eventually made to ship Toronto's garbage to the Adams Mine , an abandoned open pit mine in Northern Ontario , once the Keele Valley site closed. But controversy grew into vehement objection as the time neared, and eventually

2905-566: 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 biological reactors ( bioreactors ) 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 (See environmental engineering ). Usually, aerobic decomposition

2988-692: 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. Landfilling is currently the major method of municipal waste disposal in India. India also has Asia's largest dumping ground in Deonar, Mumbai. However, issues frequently arise due to

3071-452: The RO membranes. Reverse osmosis applicability is limited by conductivity, organics, and scaling inorganic elements such as CaSO 4 , Si, and Ba. In some older landfills, leachate was directed to the sewers , but this can cause a number of problems. Toxic metals from leachate passing through the sewage treatment plant concentrate in the sewage sludge, making it difficult or dangerous to dispose of

3154-456: The ability to order exact amounts of the liner. Ordering precise amounts from the manufacturer prevents surplus and over-spending. Another advantage to GCLs is that the liner can be used in areas without an adequate clay source. On the other hand, GCLs are heavy and cumbersome, and their installation is very labor-intensive. In addition to being arduous and difficult under normal conditions, installation can be cancelled during damp conditions because

3237-415: The age of landfill, type of waste, moisture content and other factors. For example, the maximum amount of landfill gas produced can be illustrated a simplified net reaction of diethyl oxalate that accounts for these simultaneous reactions: 4 C 6 H 10 O 4 + 6 H 2 O → 13 CH 4 + 11 CO 2 On average, about half of the volumetric concentration of landfill gas is CH 4 and slightly less than half

3320-604: The agreement was canceled. By the time the Keele Valley site closed at the end of 2002, the city had made a new deal, to ship its garbage by truck to Carleton Farms Landfill in Sumpter Township, Michigan , United States. Issues at the Canada–United States border and opposition from residents in Michigan prompted the need to look for alternate sites or expand the city's recycling programs. The Michigan contract survived

3403-507: The alarming growth rate of landfills and poor management by authorities. On and under surface fires have been commonly seen in the Indian landfills over the last few years. 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

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3486-510: The atmosphere through photosynthesis, no new carbon enters the carbon cycle and the atmospheric concentration of CO 2 is not affected. Carbon dioxide traps heat in the atmosphere, contributing to climate change . In properly managed landfills, gas is collected and flared or recovered for landfill gas utilization . Poorly run landfills may become nuisances because of vectors such as rats and flies which can spread infectious diseases . The occurrence of such vectors can be mitigated through

3569-551: The bands to $ 4.27 per tonne of garbage deposited at the landfill, or approximately $ 500,000 per year. The contract to ship household garbage to Michigan ended in 2010, at which point use of the Green Lane landfill began. 42°48′49″N 81°19′35″W  /  42.8136°N 81.32637°W  / 42.8136; -81.32637 Leachate A leachate is any liquid that, in the course of passing through matter, extracts soluble or suspended solids, or any other component of

3652-472: The bentonite would absorb the moisture, making the job even more burdensome and tedious. The leachate drainage system is responsible for the collection and transport of the leachate collected inside the liner. The pipe dimensions, type, and layout must all be planned with the weight and pressure of waste, and transport vehicles in mind. The pipes are located on the floor of the cell. Above the network lies an enormous amount of weight and pressure. To support this,

3735-418: The cement paste onto the surface of the steel reinforcement, thereby catalyzing its oxidation and degradation . Leachates can be genotoxic in nature. A possible risk for the aquatic environment due to the occurrence of organic micropollutants in raw or treated landfill leachates has also been reported in recent studies. Landfill A landfill is a site for the disposal of waste materials. It

3818-467: The chemical composition. In sites with large volumes of building waste, especially those containing gypsum plaster, the reaction of leachate with the gypsum can generate large volumes of hydrogen sulfide , which may be released in the leachate and may also form a large component of the landfill gas. The physical appearance of leachate when it emerges from a typical landfill site is a strongly odoured black-, yellow- or orange-coloured cloudy liquid. The smell

3901-418: 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. The term landfill is usually shorthand for a municipal landfill or sanitary landfill. These facilities were first introduced early in

3984-656: The field of assessment techniques and remedial technology of environmental issues originating from landfill leachate has been reviewed in an article published in Critical Reviews in Environmental Science and Technology journal. A possible ecological threat for the aquatic environment due to the occurrence of organic micropollutants in raw and treated landfill leachates has also been reported. Leachate collection systems can experience many problems including clogging with mud or silt. Bioclogging can be exacerbated by

4067-436: The ground around landfills must be tested for leachate to prevent pollutants from contaminating groundwater . Rotting food and other decaying organic waste create decomposition gases , especially CO 2 and CH 4 from aerobic and anaerobic decomposition, respectively. Both processes occur simultaneously in different parts of a landfill. In addition to available O 2 , the fraction of gas constituents will vary, depending on

4150-525: The ground during an earthquake . Once full, the area over a landfill site may be reclaimed for other uses. Operators of well-run landfills for non-hazardous waste meet predefined specifications by applying techniques to: 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 scale or weighbridge may weigh waste collection vehicles on arrival and personnel may inspect loads for wastes that do not accord with

4233-565: The growth of micro-organisms in the conduit. The conditions in leachate collection systems are ideal for micro-organisms to multiply. Chemical reactions in the leachate may also cause clogging through generation of solid residues. The chemical composition of leachate can weaken pipe walls, which may then fail. Leachate can also be produced from land that was contaminated by chemicals or toxic materials used in industrial activities such as factories , mines or storage sites. Composting sites in areas of high rainfall also produce leachate. Leachate

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4316-400: The impact of converting some leachate volume into landfill gas and reducing the overall volume of leachate for disposal. However, it also tended to increase substantially the concentrations of contaminant materials, making it a more difficult waste to treat. The most common method of handling collected leachate is on-site treatment. When treating leachate on-site, the leachate is pumped from

4399-449: The landfill at a rate sufficient to prevent an unacceptable hydraulic head occurring at any point over the lining system. There are many components to a collection system including pumps, manholes, discharge lines and liquid level monitors. However, there are four main components which govern the overall efficiency of the system. These four elements are liners, filters, pumps and sumps. Natural and synthetic liners may be utilized as both

4482-427: The landfill bioreactor strata gradually decreases. Microbial populations grow, density increases. Aerobic biodegradation dominates, i.e. the primary electron acceptor is O 2 . The O 2 is rapidly degraded by the existing microbial populations. The decreasing O 2 leads to less aerobic and more anaerobic conditions in the layers. The primary electron acceptors during transition are nitrates and sulphates since O 2

4565-469: The landfill can be significant and can be mitigated by wheel washing systems . Pollution of the local environment , such as contamination of groundwater or aquifers or soil contamination may occur, as well. When precipitation falls on open landfills, water percolates through the garbage and becomes contaminated with suspended and dissolved material, forming leachate. If this is not contained it can contaminate groundwater. All modern landfill sites use

4648-401: The landfill space for waste. Geocomposites are a combination of synthetic materials that are ordinarily used singly. A common type of geocomposite is a geonet that is heat-bonded to two layers of geotextile, one on each side. The geocomposite serves as a filter and drainage medium. Geosynthetic clay liners are a type of combination liner. One advantage to using a geosynthetic clay liner (GCL) is

4731-451: The landfill's waste-acceptance criteria. 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, compactors or bulldozers can spread and 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

4814-555: The law to dispose of waste materials. Leachate streams running directly into the aquatic environment have both an acute and chronic impact on the environment, which may be very severe and can severely diminish bio-diversity and greatly reduce populations of sensitive species. Where toxic metals and organics are present this can lead to chronic toxin accumulation in both local and far distant populations. Rivers impacted by leachate are often yellow in appearance and often support severe overgrowths of sewage fungus . The contemporary research in

4897-519: The leachate collection system. Such systems are prone to internal failure as landfills suffer large internal movements as waste decomposes unevenly and thus buckles and distorts pipes. If a leachate collection system fails, leachate levels will slowly build in a site and may even over-top the containing membrane and flow out into the environment. Rising leachate levels can also wet waste masses that have previously been dry, triggering further active decomposition and leachate generation. Thus, what appears to be

4980-456: The leachate. The acid formation phase intermediary products (e.g., acetic, propionic, and butyric acids) are converted to CH 4 and CO 2 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 4 and CO 2 gas production. This

5063-406: The lower explosive limit. This entails methane stripping from the leachate. The greatest environmental risks occur in the discharges from older sites constructed before modern engineering standards became mandatory and also from sites in the developing world where modern standards have not been applied. There are also substantial risks from illegal sites and ad-hoc sites used by organizations outside

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5146-403: The material that it has passed through. Leachate from a landfill varies widely in composition depending on the age of the landfill and the type of waste that it contains. It usually contains both dissolved and suspended material. The generation of leachate is caused principally by precipitation percolating through waste deposited in a landfill. Once in contact with decomposing solid waste,

5229-563: The material through which it has passed. Leachate is a widely used term in the environmental sciences where it has the specific meaning of a liquid that has dissolved or entrained environmentally harmful substances that may then enter the environment. It is most commonly used in the context of land-filling of putrescible or industrial waste. In the narrow environmental context leachate is therefore any liquid material that drains from land or stockpiled material and contains significantly elevated concentrations of undesirable material derived from

5312-452: The most important, but pathogenic organism counts reduce rapidly with time in the landfill, so this only applies to the freshest leachate. Toxic substances may, however, be present in variable concentrations, and their presence is related to the nature of the waste deposited. Most landfills containing organic material will produce methane , some of which dissolves in the leachate. This could, in theory, be released in poorly ventilated areas in

5395-649: The percolating water becomes contaminated, and if it then flows out of the waste material it is termed leachate. Additional leachate volume is produced during this decomposition of carbonaceous material producing a wide range of other materials including methane , carbon dioxide and a complex mixture of organic acids , aldehydes , alcohols and simple sugars. The risks of leachate generation can be mitigated by properly designed and engineered landfill sites, such as those that are constructed on geologically impermeable materials or sites that use impermeable liners made of geomembranes or engineered clay . The use of linings

5478-418: The pipes can either be flexible or rigid, but the joints to connect the pipes yield better results if the connections are flexible. An alternative to placing the collection system underneath the waste is to position the conduits in trenches or above grade. The collection pipe network of a leachate collection system drains, collects, and transports leachate through the drainage layer to a collection sump where it

5561-427: The plant operators are finding that leachates are difficult waste streams to treat. This is because leachates contain very high ammoniacal nitrogen concentrations, are usually very acidic, are often anoxic and, if received in large volumes relative to the incoming sewage flow, lack the phosphorus needed to prevent nutrient starvation for the biological communities that perform the sewage treatment processes. The result

5644-418: The presence of iron salts in solution and in suspension. It also quickly develops a bacterial flora often comprising substantial growths of Sphaerotilus natans . In the UK, in the late 1960s, central Government policy was to ensure new landfill sites were being chosen with permeable underlying geological strata to avoid the build-up of leachate. This policy was dubbed "dilute and disperse". However, following

5727-606: The privately owned Green Lane landfill site. Councillors opposed to the agreement accused Toronto Mayor David Miller of pushing through a secretive deal, and there was also a strong reaction from residents and members of parliament from the London metropolitan area. Jane Pitfield , who ran (and lost) against Miller in the November 2006 municipal election, advocated incineration as an alternative method of disposing of waste. Many Toronto environmental groups opposed it, but supporters argued that

5810-682: The samples and perfluorooctanoic acid in 68%. Bisphenol A, valsartan and 2-OH-benzothiazole had the highest average concentrations in raw leachates, after biological treatment and after reverse osmosis, respectively. In older landfills and those with no membrane between the waste and the underlying geology, leachate is free to leave the waste and flow directly into the groundwater . In such cases, high concentrations of leachate are often found in nearby springs and flushes. As leachate first emerges it can be black in colour, anoxic, and possibly effervescent , with dissolved and entrained gases. As it becomes oxygenated it tends to turn brown or yellow because of

5893-400: The site have an engineered lining. In the wake of European advancements, the United States increased its development of leachate retaining and collection systems. This quickly led from lining in principle to the use of multiple lining layers in all landfills (excepting those truly inert). The primary criterion for design of the leachate system is that all leachate be collected and removed from

5976-484: The sludge without incurring a risk to the environment. In Europe , regulations and controls have improved in recent decades, and toxic wastes are now no longer permitted to be disposed of in the Municipal Solid Waste landfills, and in most developed countries the metals problem has diminished. Paradoxically, however, as sewage treatment plant discharges are being improved throughout Europe and many other countries,

6059-434: The sump into the treatment tanks. The leachate may then be mixed with chemical reagents to modify the pH and to coagulate and settle solids and to reduce the concentration of hazardous matter. Traditional treatment involved a modified form of activated sludge to substantially reduce the dissolved organic content. Nutrient imbalance can cause difficulties in maintaining an effective biological treatment stage. The treated liquid

6142-608: The sump is removed by pumping to a vehicle, to a holding facility for subsequent vehicle pickup, or to an on-site treatment facility. Sump dimensions are governed by the amount of leachate to be stored, pump capacity, and minimum pump drawdown. The volume of the sump must be sufficient to hold the maximum amount of leachate anticipated between pump cycles, plus an additional volume equal to the minimum pump drawdown volume. Sump size should also consider dimensional requirements for conducting maintenance and inspection activities. Sump pumps may operate with preset cycling times or, if leachate flow

6225-475: The technology has improved and incineration is now less polluting. Even with 60% diversion through the green bin and recycling programs, residual waste from the Greater Toronto Area would amass 2,200 tonnes (2,425 tons) a day or 800,000 tonnes (882,000 tons) a year. In April 2007, the city signed contracts with First Nations bands whose reserves were close to the proposed landfill, which would entitle

6308-445: The temperature rises and the pH falls rapidly with the result that many metal ions that are relatively insoluble at neutral pH become dissolved in the developing leachate. The decomposition processes themselves release more water, which adds to the volume of leachate. Leachate also reacts with materials that are not prone to decomposition themselves, such as fire ash, cement -based building materials and gypsum-based materials changing

6391-543: The treatment plant. All plants in Europe must now be assessed under the EU ATEX Directive and zoned where explosion risks are identified to prevent future accidents. The most important requirement is the prevention of the discharge of dissolved methane from untreated leachate into public sewers, and most sewage treatment authorities limit the permissible discharge concentration of dissolved methane to 0.14 mg/L, or 1/10 of

6474-531: 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. 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

6557-432: The use of daily cover . Other potential issues include wildlife disruption due to occupation of habitat and animal health disruption caused by consuming waste from landfills, dust, odor, noise pollution , and reduced local property values. Gases are produced in landfills due to the anaerobic digestion by microbes. In a properly managed landfill, this gas is collected and used. Its uses range from simple flaring to

6640-404: The waste depend on how well microbial populations function in syntrophy , i.e. an interaction of different populations to provide each other's nutritional needs.: The life cycle of a municipal landfill undergoes five distinct phases: As the waste is placed in the landfill, the void spaces contain high volumes of molecular oxygen (O 2 ). With added and compacted wastes, the O 2 content of

6723-435: 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 increases with increasing concentrations of the more recalcitrant compounds compared to the more reactive compounds in the leachate. Successful conversion and stabilization of

6806-416: 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

6889-399: 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", 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

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