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Health effects of coal ash-Background-Coal ash is produced at coal-fired power plants. Coal is pulverized and then burned to generate electricity. The particles that remain after burning coal are called coal ash, principally consisting of fly ash and bottom ash. Other coal combustion by-products are boiler slag, flue g... | milkshake721/2.1M-wiki-STEM |
Health effects of coal ash-Occupational health concerns-Coal ash contains many toxic substances that may affect human health, if people are exposed to them above a certain concentration in the form of particulate matter. So it is necessary to avoid situations in which employees working in coal-fired power plants or pub... | milkshake721/2.1M-wiki-STEM |
Health effects of coal ash-Health effects of toxic constituents found in coal ash-Lead: The direct exposure to lead can cause major damage to the nervous system. Lead exposure can lead to kidney disease, hearing impairment, high blood pressure, delays in development, swelling of the brain, hemoglobin damage, and male r... | milkshake721/2.1M-wiki-STEM |
Health effects of coal ash-Health effects of toxic constituents found in coal ash-Arsenic: When high amounts of arsenic is inhaled or ingested through coal ash waste, diseases such as bladder cancer, skin cancer, kidney cancer and lung cancer can develop. Ultimately, exposure of arsenic over a long period of time can c... | milkshake721/2.1M-wiki-STEM |
Health effects of coal ash-Coal ash reuse-Reuse of coal ash benefits the environment by reducing the production of greenhouse gas and reducing the need to use virgin materials. In addition, when coal ash is recycled, costs related to coal ash disposal sites are avoided.There are two forms of coal ash recycling: “encaps... | milkshake721/2.1M-wiki-STEM |
Health effects of coal ash-Coal ash waste regulations-In the United States, when coal ash is disposed into surface impoundments and landfills, the ash is regulated as a "Special Waste" (i.e., non-hazardous) under the Resource Conservation and Recovery Act (RCRA).EPA published a Coal Combustion Residuals (CCR) regulatio... | milkshake721/2.1M-wiki-STEM |
Health effects of coal ash-Coal ash waste regulations-Existing ash ponds and landfills must comply with structural and location restrictions, where applicable, or close.
A pond no longer receiving CCR is still subject to all regulations unless it is dewatered and covered by 2018. | milkshake721/2.1M-wiki-STEM |
Health effects of coal ash-Coal ash waste regulations-New ponds and landfills must include a geomembrane liner over a layer of compacted soil.In 2016, the United States Court of Appeals for the District of Columbia Circuit vacated the "early closure" provisions in the regulation at 40 CFR 257.100. EPA then extended the... | milkshake721/2.1M-wiki-STEM |
4-Piperidinone-4-Piperidinone-4-Piperidone is a derivative of piperidine with the molecular formula C5H9NO. 4-Piperidone is used as an intermediate in the manufacture of chemicals and pharmaceutical drugs. It is a List I chemical in the United States. | milkshake721/2.1M-wiki-STEM |
ZNRF1-ZNRF1-E3 ubiquitin-protein ligase ZNRF1 is an enzyme that in humans is encoded by the ZNRF1 gene.In a study identifying genes in rat that are upregulated in response to nerve damage, a gene which is highly expressed in ganglia and in the central nervous system was found. The protein encoded by the rat gene contai... | milkshake721/2.1M-wiki-STEM |
Submarine pipeline-Submarine pipeline-A submarine pipeline (also known as marine, subsea or offshore pipeline) is a pipeline that is laid on the seabed or below it inside a trench. In some cases, the pipeline is mostly on-land but in places it crosses water expanses, such as small seas, straits and rivers. Submarine pi... | milkshake721/2.1M-wiki-STEM |
Submarine pipeline-Route selection-One of the earliest and most critical tasks in a submarine pipeline planning exercise is the route selection. This selection has to consider a variety of issues, some of a political nature, but most others dealing with geohazards, physical factors along the prospective route, and othe... | milkshake721/2.1M-wiki-STEM |
Submarine pipeline-Route selection-Physical factors The primary physical factor to be considered in submarine pipeline construction is the state of the seabed – whether it is smooth (i.e., relatively flat) or uneven (corrugated, with high points and low points). If it is uneven, the pipeline will include free spans whe... | milkshake721/2.1M-wiki-STEM |
Submarine pipeline-Route selection-Other physical factors to be taken into account prior to building a pipeline include the following: Seabed mobility: Sand waves and megaripples are features that move with time, such that a pipeline that was supported by the crest of one such feature during construction may find itsel... | milkshake721/2.1M-wiki-STEM |
Submarine pipeline-Route selection-Submarine landslides: They result from high sedimentation rates and occur on steeper slopes. They can be triggered by earthquakes. When the soil around the pipe is subjected to a slide, especially if the resulting displacement is at high angle to the line, the pipe within it can incur... | milkshake721/2.1M-wiki-STEM |
Submarine pipeline-Route selection-Ice-related issues: In freezing waters, floating ice features often drift into shallower waters, and their keel comes into contact with the seabed. As they continue to drift, they gouge the seabed and can hit the pipeline. Stamukhi can also damage this structure, either by exerting hi... | milkshake721/2.1M-wiki-STEM |
Submarine pipeline-Route selection-Other uses of the seabed Proper planning of a pipeline route has to factor in a wide range of human activities that make use of the seabed along the proposed route, or that are likely to do so in the future. They include the following: Other pipelines: If and where the proposed pipeli... | milkshake721/2.1M-wiki-STEM |
Submarine pipeline-Route selection-Fishing vessels: Commercial fishing makes use of heavy fishing nets dragged on the seabed and extending several kilometers behind the trawler. This net could snag the pipeline, with potential damage to both pipeline and vessel.
Ship anchors: Ship anchors are a potential threat to pipe... | milkshake721/2.1M-wiki-STEM |
Submarine pipeline-Submarine pipeline characteristics-Submarine pipelines generally vary in diameter from 3 inches (76 mm) for gas lines, to 72 inches (1,800 mm) for high capacity lines. Wall thicknesses typically range from 10 millimetres (0.39 in) to 75 millimetres (3.0 in). The pipe can be designed for fluids at hig... | milkshake721/2.1M-wiki-STEM |
Submarine pipeline-Pipeline construction-Pipeline construction involves two procedures: assembling many pipe segments into a full line, and installing that line along the desired route. Several systems can be used – for a submarine pipeline, the choice in favor of any one of them is based on the following factors: phys... | milkshake721/2.1M-wiki-STEM |
Submarine pipeline-Pipeline construction-The pull/tow system In the pull/tow system, the submarine pipeline is assembled onshore and then towed to location. Assembly is done either parallel or perpendicular to the shoreline – in the former case, the full line can be built prior to tow out and installation. A significan... | milkshake721/2.1M-wiki-STEM |
Submarine pipeline-Pipeline construction-Surface tow: In this configuration, the pipeline remains at the surface of the water during tow, and is then sunk into position at lay site. The line has to be buoyant – this can be done with individual buoyancy units attached to it. Surface tows are not appropriate for rough se... | milkshake721/2.1M-wiki-STEM |
Submarine pipeline-Pipeline construction-Mid-depth tow: The pipeline is not buoyant – either because it is heavy or it is weighted down by hanging chains. In this configuration, the line is suspended in a catenary between two towing vessels. The shape of that catenary (the sag) is a balance between the line's weight, t... | milkshake721/2.1M-wiki-STEM |
Submarine pipeline-Pipeline construction-Off-bottom tow: This configuration is similar to the mid-depth tow, but here the line is maintained within 1 to 2 m (several feet) away from the bottom, using chains dragging on the seabed. | milkshake721/2.1M-wiki-STEM |
Submarine pipeline-Pipeline construction-Bottom tow: In this case, the pipeline is dragged onto the bottom – the line is not affected by waves and currents, and if the sea gets too rough for the tow vessel, the line can simply be abandoned and recovered later. Challenges with this type of system include: requirement fo... | milkshake721/2.1M-wiki-STEM |
Submarine pipeline-Pipeline construction-The S-lay system In the S-lay system, the pipeline assembly is done at the installation site, on board a vessel that has all the equipment required for joining the pipe segments: pipe handling conveyors, welding stations, X-ray equipment, joint-coating module, etc. The S notatio... | milkshake721/2.1M-wiki-STEM |
Submarine pipeline-Pipeline construction-The J-lay system In areas where the water is very deep, the S-lay system may not be appropriate because the pipeline leaves the stinger to go almost straight down. To avoid sharp bending at the end of it and to mitigate excessive sag bending, the tension in the pipeline would ha... | milkshake721/2.1M-wiki-STEM |
Submarine pipeline-Pipeline construction-The Reel-lay system In the reel-lay system, the pipeline is assembled onshore and is spooled onto a large drum typically about 20 metres (66 ft) x 6 metres (20 ft) in size, mounted on board a purpose-built vessel. The vessel then goes out to location to lay the pipeline. Onshore... | milkshake721/2.1M-wiki-STEM |
Submarine pipeline-Stabilisation-Several methods are used to stabilise and protect submarine pipelines and their components. These may be used alone or in combinations. | milkshake721/2.1M-wiki-STEM |
Submarine pipeline-Stabilisation-Trenching and burial A submarine pipeline may be laid inside a trench as a means of safeguarding it against fishing gear (e.g. anchors) and trawling activity. This may also be required in shore approaches to protect the pipeline against currents and wave action (as it crosses the surf z... | milkshake721/2.1M-wiki-STEM |
Submarine pipeline-Stabilisation-Mechanical cutting: This system uses chains or cutter disks to dig through and remove harder soils, including boulders, from below the pipeline.
Plowing: The plowing principle, which was initially used for pre-lay trenching, has evolved into sophisticated systems that are lighter in siz... | milkshake721/2.1M-wiki-STEM |
Submarine pipeline-Stabilisation-Dredging/excavation: In shallower water, the soil can be removed with a dredger or an excavator prior to laying the pipeline. This can be done in a number of ways, notably with a ′′cutter-suction′′ system, with the use of buckets or with a backhoe.″A buried pipe is far better protected ... | milkshake721/2.1M-wiki-STEM |
Submarine pipeline-Stabilisation-Mattresses Mattresses may be laid over the pipeline, or both under and over it depending on the substrate.
Frond mattresses have an effect similar to seaweed and tend to cause sand to accumulate. They must be anchored to the bottom to prevent being washed away.
Concrete mattresses are u... | milkshake721/2.1M-wiki-STEM |
Submarine pipeline-Environmental and legal issues-The Espoo Convention created certain requirements for notification and consultation where a project is likely to have transboundary environmental effects. Scholars are divided on how effective Espoo is at mitigating environmental harm. Law of the Sea concepts involved i... | milkshake721/2.1M-wiki-STEM |
Water park-Water park-A water park (also waterpark, water world, or aquapark) is an amusement park that features water play areas such as swimming pools, water slides, splash pads, water playgrounds, and lazy rivers, as well as areas for floating, bathing, swimming, and other barefoot environments. Modern water parks m... | milkshake721/2.1M-wiki-STEM |
Water park-History-Water parks have grown in popularity since their introduction in the late 1940s and early 1950s. The United States has the largest and most concentrated water park market, with over 1,000 water parks and dozens of new parks opening each year. Major organizations are the IAAPA (International Associati... | milkshake721/2.1M-wiki-STEM |
Water park-History-A process of concentration can be observed in the hybrid versions of theme-, amusement-, and water parks. Some water parks are more spa-oriented. For example, SchwabenQuellen has no water slides; it has instead many saunas, steam rooms, "adventure showers", and relaxation-oriented water play areas.In... | milkshake721/2.1M-wiki-STEM |
Water park-Indoor water parks-Some of the first indoor water parks are Tikibad at Duinrell (The Netherlands, 1984), Nautiland located at Haguenau (France, 1984), the Aqua Mundo at Center Parc De Eemhof located at Zeewolde (The Netherlands, 1980) and Alpamare (Pfäffikon) (Switzerland, 1977).In 1986 World Waterpark was o... | milkshake721/2.1M-wiki-STEM |
Water park-Indoor water parks-The largest indoor water park in the UK is Sandcastle Water Park in Blackpool, England, which opened in 1986.There are many water parks in southern Europe where the climate suits a long season. For example, in Portugal's Algarve, there are three main parks: Aqualand, Aquashow, and Slide n'... | milkshake721/2.1M-wiki-STEM |
Water park-Water play areas-Water play areas are similar to water parks and include urban beaches, splash pads, and smaller collections of water slides in many hotels and public swimming pools.
For example, the Chelsea Hotel in Toronto features a four-story water slide called the Corkscrew. | milkshake721/2.1M-wiki-STEM |
Water park-Safety-According to estimates from the U.S. Consumer Product Safety Commission, more than 4,200 people annually are sent to emergency rooms from suffering injuries on public waterslides. In July 2015, one drowning and at least three near-drownings were reported at water parks in the United States.On August 7... | milkshake721/2.1M-wiki-STEM |
Grand Central Terminal art-Grand Central Terminal art-Grand Central Terminal, one of the main railroad stations in New York City, features public art by a variety of artists. Through its status as a transportation and architectural icon, the terminal has also been depicted in many works of art. | milkshake721/2.1M-wiki-STEM |
Grand Central Terminal art-Grand Central Terminal art-Grand Central features permanent works of art, including the celestial ceiling in the Main Concourse, the Glory of Commerce work and the statue of Cornelius Vanderbilt in front of the building's south facade, and the two cast-iron eagle statues adorning the terminal... | milkshake721/2.1M-wiki-STEM |
Grand Central Terminal art-Artwork on display or part of the terminal-Facade Glory of Commerce The Glory of Commerce sculptural group rests atop the terminal's facade, directly above a broken pediment featuring a large clock. The work is also known as Progress with Mental and Physical Force or Transportation. It is abo... | milkshake721/2.1M-wiki-STEM |
Grand Central Terminal art-Artwork on display or part of the terminal-Clock There is a 13-foot-wide (4.0 m) clock on top of the south facade. It was installed in 1914 by the Self Winding Clock Company. The clock face has decorative stained glass framed in bronze, with cast-iron clock hands, the latter weighing 340 lbs.... | milkshake721/2.1M-wiki-STEM |
Grand Central Terminal art-Artwork on display or part of the terminal-Statue of Cornelius Vanderbilt A statue of Cornelius Vanderbilt, longtime owner of the New York Central, stands at the center of the terminal's south facade, directly below its clock and facing the Park Avenue Viaduct. The work was sculpted by Ernst ... | milkshake721/2.1M-wiki-STEM |
Grand Central Terminal art-Artwork on display or part of the terminal-Eagles Grand Central Terminal has two cast-iron eagle statues on display. The eagles weigh about 4,000 pounds (1,800 kg) each, have a wingspan of about 13 feet (4.0 m), and are perched on stone spheres.They are two of the 11 or 12 eagle statues that ... | milkshake721/2.1M-wiki-STEM |
Grand Central Terminal art-Artwork on display or part of the terminal-Eight identical eagle statues are elsewhere, including one at a private home in Kings Point, New York; one at the Space Farms Zoo and Museum in Beemerville, New Jersey; two at the Vanderbilt Museum in Long Island; one, known as the "Shandaken Eagle",... | milkshake721/2.1M-wiki-STEM |
Grand Central Terminal art-Artwork on display or part of the terminal-Interior Ceiling The Main Concourse's ceiling is an elliptical barrel vault. A false ceiling of square boards, installed in 1944, bears an elaborate celestial mural painted with more than 2,500 stars and several bands in gold set against a turquoise ... | milkshake721/2.1M-wiki-STEM |
Grand Central Terminal art-Artwork on display or part of the terminal-Original plans called for the ceiling to contain a skylight, but money and time ran out. Instead, a mural was painted directly on the ceiling. It was conceived in 1912 by architect Warren and painter Paul César Helleu. The latter, who had come to the... | milkshake721/2.1M-wiki-STEM |
Grand Central Terminal art-Artwork on display or part of the terminal-By the 1980s, the new ceiling was obscured by decades of grime. The dirt buildup was sometimes reported to be tar and nicotine from tobacco smoke, or diesel or coal soot from the trains in the terminal's train shed (though trains have utilized electr... | milkshake721/2.1M-wiki-STEM |
Grand Central Terminal art-Artwork on display or part of the terminal-The ceiling bears a small dark circle amid the stars above the image of Pisces. In a 1957 attempt to improve public morale after the Soviet Union launched Sputnik, an American Redstone missile was set up in the Main Concourse. With no other way to er... | milkshake721/2.1M-wiki-STEM |
Grand Central Terminal art-Artwork on display or part of the terminal-Graybar Passage mural The Graybar Passage extends from the northeast corner of the Main Concourse, underneath the Graybar Building, directly east to Lexington Avenue. The ceiling is composed of seven groin vaults, each of which has an ornamental bron... | milkshake721/2.1M-wiki-STEM |
Grand Central Terminal art-Artwork on display or part of the terminal-Sirshasana Sirshasana, an aluminum and polyester resin sculpture with crystals, was created by Donald Lipski in 1998. The sculpture hangs from the ceiling of Grand Central Market just inside its 43rd Street entrance. The chandelier has the shape of a... | milkshake721/2.1M-wiki-STEM |
Grand Central Terminal art-Artwork on display or part of the terminal-As Above, So Below As Above, So Below, a work of glass, bronze, and mosaic in several Grand Central North passageways, was made by Brooklyn-based artist Ellen Driscoll in 1998. The mosaic's five scenes, each stemming from a different continent, depic... | milkshake721/2.1M-wiki-STEM |
Grand Central Terminal art-Artwork on display or part of the terminal-Details of "As Above, So Below" A Field of Wild Flowers A Field of Wild Flowers, a mural on the walls of the Station Master's Office, was made by Roberto Juarez in 1997. The work uses many materials to give texture, strength, and beauty. Layers inclu... | milkshake721/2.1M-wiki-STEM |
Grand Central Terminal art-Artwork on display or part of the terminal-Other One of the retail areas of the Graybar Passage, currently the alcohol vendor Central Cellars, was the Grand Central Theatre or Terminal Newsreel Theatre. The movie theater lobby had walls covered with large world maps and an astronomical mural ... | milkshake721/2.1M-wiki-STEM |
Grand Central Terminal art-Artwork on display or part of the terminal-As of 2019, the space features "Landmark City", a photographic exhibit by Marc Yankus. The exhibit shows New York City landmarks, altered to appear on empty streets. | milkshake721/2.1M-wiki-STEM |
Grand Central Terminal art-Exhibitions and performances-Special exhibitions Grand Central Terminal has held a number of special exhibits, including: In June 1948, a fashion show by Filene's and the New Haven Railroad was hosted on the balcony of the Main Concourse, and a thousand square feet of sand was imported for th... | milkshake721/2.1M-wiki-STEM |
Grand Central Terminal art-Exhibitions and performances-In 1993, a portion of Ruckus Manhattan, an exhibit by Red Grooms, was displayed in the Vanderbilt Hall.
In 1995, Lost: New York Projects by Christian Boltanski involved a display, titled Lost Property, of about 5,000 personal belongings from the terminal's lost-an... | milkshake721/2.1M-wiki-STEM |
Grand Central Terminal art-Exhibitions and performances-In 1987, the performing arts organization Dancing in the Streets presented Grand Central Dances. The production involved the dance companies of Merce Cunningham, Lucinda Childs, Paul Thompson and Stephan Koplowitz, as well as the high-wire artist Philippe Petit an... | milkshake721/2.1M-wiki-STEM |
Grand Central Terminal art-Exhibitions and performances-In 1988, a Double Dutch jump-roping competition was held in the Main Concourse as part of a city-sponsored "Summer Games".
In 2011, a flash mob show by Moncler Grenoble took place in the Main Concourse.
In 2013, Nick Cave and dancers from the Alvin Ailey American ... | milkshake721/2.1M-wiki-STEM |
Grand Central Terminal art-Exhibitions and performances-Musical performances The terminal hosts numerous performances. It is also a host site for Music Under New York, where musicians can perform within various transit hubs controlled by the MTA. In Grand Central, artists can perform in the Graybar Passage as well as i... | milkshake721/2.1M-wiki-STEM |
Grand Central Terminal art-Art featuring Grand Central-Grand Central is one of the most-photographed places in New York City and the United States. A 2009 Cornell University study mapping out geotagged photos worldwide indicated the building was the fourth most photographed in New York City.One of the most famous photo... | milkshake721/2.1M-wiki-STEM |
L-threonine 3-dehydrogenase-L-threonine 3-dehydrogenase-In enzymology, a L-threonine 3-dehydrogenase (EC 1.1.1.103) is an enzyme that catalyzes the chemical reaction L-threonine + NAD+ ⇌ L-2-amino-3-oxobutanoate + NADH + H+Thus, the two substrates of this enzyme are L-threonine and NAD+, whereas its 3 products are L-2... | milkshake721/2.1M-wiki-STEM |
L-threonine 3-dehydrogenase-Structural studies-As of late 2007, 3 structures have been solved for this class of enzymes, with PDB accession codes 2D8A, 2DFV, and 2DQ4. | milkshake721/2.1M-wiki-STEM |
Hendra virus-Hendra virus-Hendra virus is a bat-borne virus that is associated with a highly fatal infection in horses and humans. Numerous disease outbreaks in Australia among horses have been caused by Hendra virus. The Hendra virus belongs to the genus Henipavirus, which also contains the Nipah virus, which has also... | milkshake721/2.1M-wiki-STEM |
Hendra virus-Pathology-Flying foxes experimentally infected with the Hendra virus develop a viraemia and shed the virus in their urine, faeces and saliva for approximately one week. There is no other indication of an illness in them. Symptoms of Hendra virus infection of humans may be respiratory, including hemorrhage ... | milkshake721/2.1M-wiki-STEM |
Hendra virus-Transmission-Flying foxes have been identified as the reservoir host of Hendra virus. A seroprevalence of 47% is found in the flying foxes, suggesting an endemic infection of the bat population throughout Australia. Horses become infected with Hendra after exposure to bodily fluid from an infected flying f... | milkshake721/2.1M-wiki-STEM |
Hendra virus-Prevention, detection and treatment-Three main approaches are currently followed to reduce the risk to humans. | milkshake721/2.1M-wiki-STEM |
Hendra virus-Prevention, detection and treatment-Vaccine for horses.In November 2012, a vaccine became available for horses. The vaccine is to be used in horses only, since, according to CSIRO veterinary pathologist Dr Deborah Middleton, breaking the transmission cycle from flying foxes to horses prevents it from passi... | milkshake721/2.1M-wiki-STEM |
Hendra virus-History-Emergence Hendra virus (originally called "Equine morbillivirus") was discovered in September 1994 when it caused the deaths of thirteen horses, and a trainer at a training complex at 10 Williams Avenue, Hendra, a suburb of Brisbane in Queensland, Australia.The index case, a mare called Drama Serie... | milkshake721/2.1M-wiki-STEM |
Hendra virus-History-Outbreak in Australia As of June 2014, a total of fifty outbreaks of Hendra virus have occurred in Australia, all involving infection of horses. As a result of these events, eighty-three horses have died or been euthanized. A further four died or were euthanized as a result of possible Hendra infec... | milkshake721/2.1M-wiki-STEM |
Hendra virus-History-Events of June–August 2011 In the years 1994–2010, fourteen events were recorded. Between 20 June 2011 and 28 August 2011, a further seventeen events were identified, during which twenty-one horses died.It is not clear why there was a sudden increase in the number of spillover events between June a... | milkshake721/2.1M-wiki-STEM |
Water purification-Water purification-Water purification is the process of removing undesirable chemicals, biological contaminants, suspended solids, and gases from water. The goal is to produce water that is fit for specific purposes. Most water is purified and disinfected for human consumption (drinking water), but w... | milkshake721/2.1M-wiki-STEM |
Water purification-Water purification-Water purification can reduce the concentration of particulate matter including suspended particles, parasites, bacteria, algae, viruses, and fungi as well as reduce the concentration of a range of dissolved and particulate matter.
The standards for drinking water quality are typic... | milkshake721/2.1M-wiki-STEM |
Water purification-Water purification-A visual inspection cannot determine if water is of appropriate quality. Simple procedures such as boiling or the use of a household activated carbon filter are not sufficient for treating all possible contaminants that may be present in water from an unknown source. Even natural s... | milkshake721/2.1M-wiki-STEM |
Water purification-Sources of water-Groundwater: The water emerging from some deep ground water may have fallen as rain many tens, hundreds, or thousands of years ago. Soil and rock layers naturally filter the ground water to a high degree of clarity and often, it does not require additional treatment besides adding ch... | milkshake721/2.1M-wiki-STEM |
Water purification-Sources of water-Upland lakes and reservoirs: Typically located in the headwaters of river systems, upland reservoirs are usually sited above any human habitation and may be surrounded by a protective zone to restrict the opportunities for contamination. Bacteria and pathogen levels are usually low, ... | milkshake721/2.1M-wiki-STEM |
Water purification-Sources of water-Rivers, canals and low land reservoirs: Low land surface waters will have a significant bacterial load and may also contain algae, suspended solids and a variety of dissolved constituents.
Atmospheric water generation is a new technology that can provide high quality drinking water b... | milkshake721/2.1M-wiki-STEM |
Water purification-Treatment-Goals The goals of the treatment are to remove unwanted constituents in the water and to make it safe to drink or fit for a specific purpose in industry or medical applications. Widely varied techniques are available to remove contaminants like fine solids, micro-organisms and some dissolve... | milkshake721/2.1M-wiki-STEM |
Water purification-Treatment-The processes below are the ones commonly used in water purification plants. Some or most may not be used depending on the scale of the plant and quality of the raw (source) water.
Pretreatment Pumping and containment – The majority of water must be pumped from its source or directed into p... | milkshake721/2.1M-wiki-STEM |
Water purification-Treatment-Storage – Water from rivers may also be stored in bankside reservoirs for periods between a few days and many months to allow natural biological purification to take place. This is especially important if treatment is by slow sand filters. Storage reservoirs also provide a buffer against sh... | milkshake721/2.1M-wiki-STEM |
Water purification-Treatment-Pre-chlorination – In many plants the incoming water was chlorinated to minimise the growth of fouling organisms on the pipe-work and tanks. Because of the potential adverse quality effects (see chlorine below), this has largely been discontinued. | milkshake721/2.1M-wiki-STEM |
Water purification-Treatment-pH adjustment Pure water has a pH close to 7 (neither alkaline nor acidic). Sea water can have pH values that range from 7.5 to 8.4 (moderately alkaline). Fresh water can have widely ranging pH values depending on the geology of the drainage basin or aquifer and the influence of contaminant... | milkshake721/2.1M-wiki-STEM |
Water purification-Treatment-Coagulation and flocculation One of the first steps in most conventional water purification processes is the addition of chemicals to assist in the removal of particles suspended in water. Particles can be inorganic such as clay and silt or organic such as algae, bacteria, viruses, protozoa... | milkshake721/2.1M-wiki-STEM |
Water purification-Treatment-The addition of inorganic coagulants such as aluminium sulfate (or alum) or iron (III) salts such as iron(III) chloride cause several simultaneous chemical and physical interactions on and among the particles. Within seconds, negative charges on the particles are neutralised by inorganic co... | milkshake721/2.1M-wiki-STEM |
Water purification-Treatment-In 1904, Allen Hazen showed that the efficiency of a sedimentation process was a function of the particle settling velocity, the flow through the tank and the surface area of tank. Sedimentation tanks are typically designed within a range of overflow rates of 0.5 to 1.0 gallons per minute p... | milkshake721/2.1M-wiki-STEM |
Water purification-Treatment-Sludge storage and removal As particles settle to the bottom of a sedimentation basin, a layer of sludge is formed on the floor of the tank which must be removed and treated. The amount of sludge generated is significant, often 3 to 5 per cent of the total volume of water to be treated. The... | milkshake721/2.1M-wiki-STEM |
Water purification-Treatment-Floc blanket clarifiers A subcategory of sedimentation is the removal of particulates by entrapment in a layer of suspended floc as the water is forced upward. The major advantage of floc blanket clarifiers is that they occupy a smaller footprint than conventional sedimentation. The disadva... | milkshake721/2.1M-wiki-STEM |
Water purification-Treatment-Water supplies that are particularly vulnerable to unicellular algae blooms and supplies with low turbidity and high colour often employ DAF.: 9.46 Filtration After separating most floc, the water is filtered as the final step to remove remaining suspended particles and unsettled floc. | milkshake721/2.1M-wiki-STEM |
Water purification-Treatment-Rapid sand filters The most common type of filter is a rapid sand filter. Water moves vertically through sand which often has a layer of activated carbon or anthracite coal above the sand. The top layer removes organic compounds, which contribute to taste and odour. The space between sand p... | milkshake721/2.1M-wiki-STEM |
Water purification-Treatment-To clean the filter, water is passed quickly upward through the filter, opposite the normal direction (called backflushing or backwashing) to remove embedded or unwanted particles. Prior to this step, compressed air may be blown up through the bottom of the filter to break up the compacted ... | milkshake721/2.1M-wiki-STEM |
Water purification-Treatment-Some water treatment plants employ pressure filters. These work on the same principle as rapid gravity filters, differing in that the filter medium is enclosed in a steel vessel and the water is forced through it under pressure.
Advantages: Filters out much smaller particles than paper and ... | milkshake721/2.1M-wiki-STEM |
Water purification-Treatment-Slow sand filters Slow sand filters may be used where there is sufficient land and space, as the water flows very slowly through the filters. These filters rely on biological treatment processes for their action rather than physical filtration. They are carefully constructed using graded la... | milkshake721/2.1M-wiki-STEM |
Water purification-Treatment-Bank filtration In bank filtration, natural sediments in a riverbank are used to provide the first stage of contaminant filtration. While typically not clean enough to be used directly for drinking water, the water gained from the associated extraction wells is much less problematic than ri... | milkshake721/2.1M-wiki-STEM |
Water purification-Treatment-Membrane filtration Membrane filters are widely used for filtering both drinking water and sewage. For drinking water, membrane filters can remove virtually all particles larger than 0.2 μm—including giardia and cryptosporidium. Membrane filters are an effective form of tertiary treatment w... | milkshake721/2.1M-wiki-STEM |
Water purification-Treatment-Removal of ions and other dissolved substances Ultrafiltration membranes use polymer membranes with chemically formed microscopic pores that can be used to filter out dissolved substances avoiding the use of coagulants. The type of membrane media determines how much pressure is needed to dr... | milkshake721/2.1M-wiki-STEM |
Water purification-Treatment-Precipitative softening:: 13.12–13.58 Water rich in hardness (calcium and magnesium ions) is treated with lime (calcium oxide) and/or soda-ash (sodium carbonate) to precipitate calcium carbonate out of solution utilising the common-ion effect. | milkshake721/2.1M-wiki-STEM |
Water purification-Treatment-Electrodeionization: Water is passed between a positive electrode and a negative electrode. Ion-exchange membranes allow only positive ions to migrate from the treated water toward the negative electrode and only negative ions toward the positive electrode. High purity deionised water is pr... | milkshake721/2.1M-wiki-STEM |
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