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Landfill Liner
A landfill liner, or composite liner, is intended to be a low permeable barrier, which is laid down under engineered landfill sites. Until it deteriorates, the liner retards migration of leachate, and its toxic constituents, into underlying aquifers or nearby rivers from causing potentially irreversible contamination of the local waterway and its sediments. Modern landfills generally require a layer of compacted clay with a minimum required thickness and a maximum allowable hydraulic conductivity, overlaid by a high-density polyethylene geomembrane. The United States Environmental Protection Agency has stated that the barriers "will ultimately fail," while sites remain threats for "thousands of years," suggesting that modern landfill designs delay but do not prevent ground and surface water pollution. Chipped or waste tires are used to support and insulate the liner. Types Different types of liquid trash will vary in their chemical properties and threat posed to the local env ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geosynthetic Clay Liner
Different types of fabric used for geosynthetic clay liners Geosynthetic clay liners (GCLs) are factory manufactured hydraulic barriers consisting of a layer of bentonite or other very low-permeability material supported by geotextiles and/or geomembranes, mechanically held together by needling, stitching, or chemical adhesives. Due to environmental laws, any seepage from landfills must be collected and properly disposed of, otherwise contamination of the surrounding ground water could cause major environmental and/or ecological problems. The lower the hydraulic conductivity the more effective the GCL will be at retaining seepage inside of the landfill. Bentonite composed predominantly (>70%) of montmorillonite or other expansive clays, are preferred and most commonly used in GCLs. A general GCL construction would consist of two layers of geosynthetics stitched together enclosing a layer of natural or processed sodium bentonite. Typically, woven and/or non-woven textile geos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Landfills In The United States
Municipal solid waste (MSW) – more commonly known as Waste, trash or garbage – consists of everyday items people use and then throw away, such as product packaging, grass clippings, furniture, clothing, bottles, food scraps and papers. In 2018, Americans generated about 265.3 million tonnes of waste. In the United States, landfills are regulated by the United States Environmental Protection Agency, Environmental Protection Agency (EPA) and the states' environmental agencies. Municipal solid waste landfills (MSWLF) are required to be designed to protect the Natural environment, environment from contaminants that may be present in the solid waste stream. Some materials may be banned from disposal in municipal solid waste landfills including common household items such as paints, cleaners/chemicals, motor oil, Battery (electricity), batteries, pesticides, and electronics. These products, if mishandled, can be dangerous to health and the environment, creating leachate into water ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Landfill Mining
Landfill mining and reclamation (LFMR) is a process which excavates and processes solid wastes which have previously been landfilled. The process aims to reduce the amount of landfill mass encapsulated within the closed landfill and/or temporarily remove hazardous material to allow protective measures to be taken before the landfill mass is replaced. In the process, mining recovers valuable recyclable materials, a combustible fraction, soil, and landfill space. The aeration of the landfill soil is a secondary benefit with regard to the landfill's future use. The combustible fraction is useful for power generation. The overall appearance of the landfill mining procedure is a sequence of processing machines laid out in a functional conveyor system. The operating principle is to excavate, sieve and sort the landfill material. The Hiriya landfill operated by the Dan Region Authority next to the city of Tel Aviv, Israel, introduced the concept of mining as early as 1953. Waste conta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Daily Cover
The daily cover on an operational landfill site is the layer of compressed soil or earth which is laid on top of a day's deposition of waste. Benefits of using daily cover include: * Reduction of odor and air emissions * Control of disease vectors (birds, insects, and rodents) * Improved surface stability for landfill vehicles * Control of litter * Reduction of leachate generation (cover reduces infiltration of rainwater and runoff into the waste mass) * Fire prevention (cover reduces contact of combustible materials with air and ignition sources, and can act as a temporary firebreak) Work at the Fresno Sanitary Landfill was instrumental in establishing the need and utility of daily cover. Federal regulations in the United States require a minimum of six (6) inches of daily cover to be used at the end of each day. While soils are the traditional materials employed in daily cover, alternative daily cover (ADC) options such as "green waste", mixtures of paper sludge, tire derive ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biogas
Biogas is a gaseous renewable energy source produced from raw materials such as agricultural waste, manure, municipal waste, plant material, sewage, green waste, Wastewater treatment, wastewater, and food waste. Biogas is produced by anaerobic digestion with anaerobic organisms or methanogens inside an Anaerobic digestion, anaerobic digester, biodigester or a bioreactor. The gas composition is primarily methane () and carbon dioxide () and may have small amounts of hydrogen sulfide (), moisture and siloxanes. The methane can be combusted or oxidized with oxygen. This energy release allows biogas to be used as a fuel; it can be used in fuel cells and for heating purpose, such as in cooking. It can also be used in a gas engine to convert the energy in the gas into electricity and heat. After removal of carbon dioxide and hydrogen sulfide it can be compressed natural gas, compressed in the same way as natural gas and used to power Alternative fuel vehicle, motor vehicles. In the Un ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bioclogging
Bioclogging or biological clogging refers to the blockage of pore space in soil by microbial biomass, including active cells and their byproducts such as extracellular polymeric substance (EPS). The microbial biomass obstructs pore spaces, creating an impermeable layer in the soil and significantly reducing water infiltration rates. Bioclogging occurs under continuous ponded infiltration at various field conditions such as artificial recharge ponds, percolation trenches, irrigation channels, sewage treatment systems, constructed wetlands, landfill liners and natural systems such as riverbeds and soils. It also affects groundwater flow in the aquifer, such as ground source heat pumps, permeable reactive barriers, and microbial enhanced oil recovery. Bioclogging is a significant problem where water infiltration is hampered and countermeasures such as regular drying of the system can reduce the levels of bioclogging. However, bioclogging can also serve beneficial purposes in spe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pond Liner
A pond liner is an impermeable geomembrane used for retention of liquids, including the lining of reservoirs, retention basins, hazardous and nonhazardous surface impoundments, garden ponds and artificial streams in parks and gardens. Installation Pond liners need to be protected from sharp objects (for example, stones) below the liner and from being punctured by any objects in the water body. Protection can be provided with layers of sand, geotextiles (particularly needle-punched nonwovens) and other materials. Pond liners are manufactured in rolls or accordion-folded on pallets. When deployed in the field their edges and ends are overlapped and seamed together. Methods are thermal fusion, solvents, adhesives and tapes. The edge of the pond liner is generally rolled over the top of the soil slope and secured in an anchor trench or it can be fixed to a vertical wall made of wood or concrete. Box-shaped pond liners can be made for rectangular structures. The vast majority of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geomembrane
A geomembrane is very low permeability synthetic membrane liner or barrier used with any geotechnical engineering related material so as to control fluid (liquid or gas) migration in a human-made project, structure, or system. Geomembranes are made from relatively thin continuous polymeric sheets, but they can also be made from the impregnation of geotextiles with asphalt, elastomer or polymer sprays, or as multilayered bitumen geocomposites. Continuous polymer sheet geomembranes are, by far, the most common. Manufacturing The manufacturing of geomembranes begins with the production of the raw materials, which include the polymer resin, and various additives such as antioxidants, plasticizers, fillers, carbon black, and lubricants (as a processing aid). These raw materials (i.e., the "formulation") are then processed into sheets of various widths and thickness by extrusion, calendering, and/or spread coating. A 2010 estimate cited geomembranes as the largest geosynthetic ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geotextiles
Geotextiles are versatile permeable fabrics that, when used in conjunction with soil, can effectively perform multiple functions, including separation, filtration, reinforcement, protection, and drainage. Typically crafted from polypropylene or polyester, geotextile fabrics are available in two primary forms: woven, which resembles traditional mail bag sacking, and nonwoven, which resembles felt. Geotextile composites have been introduced and products such as geogrids and meshes have been developed. Geotextiles are durable and are able to soften a fall. Overall, these materials are referred to as geosynthetics and each configuration—geonets, geosynthetic clay liners, geogrids, geotextile tubes, and others—can yield benefits in geotechnical and environmental engineering design. History Geotextiles were originally intended to be a substitute for granular soil filters. Geotextiles can also be referred to as ''filter fabrics''. In the 1950s, R.J. Barrett began working usin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Environmental Stress Cracking
Environmental Stress Cracking (ESC) is one of the most common causes of unexpected brittle failure of thermoplastic (especially amorphous) polymers known at present. According to ASTM D883, stress cracking is defined as "an external or internal crack in a plastic caused by tensile stresses less than its short-term mechanical strength". This type of cracking typically involves brittle cracking, with little or no ductile drawing of the material from its adjacent failure surfaces. Environmental stress cracking may account for around 15-30% of all plastic component failures in service.H. F. Mark (2004). Encyclopedia of Polymers Science and Technology – 3rd Ed. Vol 12. John Miley & Sons Inc. This behavior is especially prevalent in glassy, amorphous thermoplastics. Amorphous polymers exhibit ESC because of their loose structure which makes it easier for the fluid to permeate into the polymer. Amorphous polymers are more prone to ESC at temperature higher than their glass tran ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subsoil
Subsoil is the layer of soil under the topsoil on the surface of the ground. Like topsoil, it is composed of a variable mixture of small particles such as sand, silt and clay, but with a much lower percentage of organic matter and humus. The subsoil is labeled the soil horizon, B Horizon in most soil mapping systems. Because it has less organic matter than topsoil, subsoil soil color, soil colour is mainly derived from iron oxides. Iron oxides and clay minerals form due to soil formation, weathering. Rainfall moves these weathering products downward as solutes and colloids by rainfall. The subsoil is the depth where these weathering products accumulate. The accumulation of clay minerals, iron, aluminum, and organic compounds is called illuviation. Whereas the topsoil tends to be the depth of greatest physical, chemical, and biological activity, the subsoil is the depth of most deposition. Due to physical, chemical, and biological activity, the subsoil generally has a soil struct ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
