74-422: Wastewater (or waste water ) is water generated after the use of freshwater , raw water , drinking water or saline water in a variety of deliberate applications or processes. Another definition of wastewater is "Used water from any combination of domestic, industrial, commercial or agricultural activities, surface runoff / storm water, and any sewer inflow or sewer infiltration ". In everyday usage, wastewater
148-539: A desert climate often face physical water scarcity. Central Asia , West Asia , and North Africa are examples of arid areas. Economic water scarcity results from a lack of investment in infrastructure or technology to draw water from rivers, aquifers , or other water sources. It also results from weak human capacity to meet water demand. Many people in Sub-Saharan Africa are living with economic water scarcity. An important concern for hydrological ecosystems
222-520: A 10%+ compound rate, doubling in abundance every seven years. There are now about 21,000 desalination plants in operation around the globe. The biggest ones are in the United Arab Emirates , Saudi Arabia , and Israel. The world's largest desalination plant is located in Saudi Arabia ( Ras Al-Khair Power and Desalination Plant ) with a capacity of 1,401,000 cubic meters per day. Desalination
296-490: A April 2024, researchers from the Australian National University published experimental results of a novel technique for desalination. This technique, thermodiffusive desalination, passes saline water through a channel with a temperature gradient. Species migrate under this temperature gradient in a process known a thermodiffusion. Researchers then separated the water into fractions. After multiple passes through
370-479: A buffer tank on a hill with seawater. The reverse osmosis process receives its pressurized seawater feed in non-sunlight hours by gravity, resulting in sustainable drinking water production without the need for fossil fuels, an electricity grid or batteries. Nano-tubes are also used for the same function (i.e., Reverse Osmosis). Forward osmosis uses a semi-permeable membrane to effect separation of water from dissolved solutes. The driving force for this separation
444-526: A collection of 17 interlinked global goals designed to be a "blueprint to achieve a better and more sustainable future for all". Targets on fresh water conservation are included in SDG 6 (Clean water and sanitation) and SDG 15 (Life on land). For example, Target 6.4 is formulated as "By 2030, substantially increase water-use efficiency across all sectors and ensure sustainable withdrawals and supply of freshwater to address water scarcity and substantially reduce
518-681: A decade of regional drought. By the late 1960s and the early 1970s, RO started to show promising results to replace traditional thermal desalination units. Research took place at state universities in California, at the Dow Chemical Company and DuPont . Many studies focus on ways to optimize desalination systems. The first commercial RO plant, the Coalinga desalination plant, was inaugurated in California in 1965 for brackish water . Dr. Sidney Loeb , in conjunction with staff at UCLA , designed
592-402: A drinking water supply it remains vital to protect due to its ability to carry contaminants and pollutants from the land into lakes and rivers, which constitute a significant percentage of other people's freshwater supply. It is almost ubiquitous underground, residing in the spaces between particles of rock and soil or within crevices and cracks in rock, typically within 100 m (330 ft) of
666-627: A large pilot plant to gather data on RO, but was successful enough to provide freshwater to the residents of Coalinga. This was a milestone in desalination technology, as it proved the feasibility of RO and its advantages compared to existing technologies (efficiency, no phase change required, ambient temperature operation, scalability, and ease of standardization). A few years later, in 1975, the first sea water reverse osmosis desalination plant came into operation. As of 2000, more than 2000 plants were operated. The largest are in Saudi Arabia, Israel, and
740-428: A larger salt content. Freshwater habitats can be classified by different factors, including temperature, light penetration, nutrients, and vegetation. There are three basic types of freshwater ecosystems: Lentic (slow moving water, including pools , ponds , and lakes ), lotic (faster moving water, for example streams and rivers ) and wetlands (areas where the soil is saturated or inundated for at least part of
814-434: A lower temperature, when the ambient atmospheric pressure is less than usual atmospheric pressure. Thus, because of the reduced pressure, low-temperature "waste" heat from electrical power generation or industrial processes can be employed. Water is evaporated and separated from sea water through multi-stage flash distillation , which is a series of flash evaporations . Each subsequent flash process uses energy released from
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#1733086208267888-479: A multidisciplinary desalination methodology in the IBTS Greenhouse . The IBTS is an industrial desalination (power)plant on one side and a greenhouse operating with the natural water cycle (scaled down 1:10) on the other side. The various processes of evaporation and condensation are hosted in low-tech utilities, partly underground and the architectural shape of the building itself. This integrated biotectural system
962-418: A significant effect on efficiency and durability. A study found that a membrane created via co-axial electrospinning of PVDF - HFP and silica aerogel was able to filter 99.99% of salt after continuous 30-day usage. The leading process for desalination in terms of installed capacity and yearly growth is reverse osmosis (RO). The RO membrane processes use semipermeable membranes and applied pressure (on
1036-519: A single factor. Groundwater showed greater resilience to climate change than expected, and areas with an increasing threshold between 0.34 and 0.39 aridity index exhibited significant sensitivity to climate change. Land-use could affect infiltration and runoff processes. The years of most recharge coincided with the most precipitation anomalies, such as during El Niño and La Niña events. Three precipitation-recharge sensitivities were distinguished: in super arid areas with more than 0.67 aridity index, there
1110-492: A vacuum. Under vacuum conditions the ice, desalinated, is melted and diverted for collection and the salt is collected. Electrodialysis uses electric potential to move the salts through pairs of charged membranes, which trap salt in alternating channels. Several variances of electrodialysis exist such as conventional electrodialysis , electrodialysis reversal . Electrodialysis can simultaneously remove salt and carbonic acid from seawater. Preliminary estimates suggest that
1184-482: A vertical tube seawater distilling unit that, thanks to its simplicity of design and ease of construction, gained popularity for shipboard use. Land-based units did not significantly appear until the latter half of the nineteenth century. In the 1860s, the US Army purchased three Normandy evaporators, each rated at 7000 gallons/day and installed them on the islands of Key West and Dry Tortugas . Another land-based plant
1258-512: Is CETO , a wave power technology that desalinates seawater using submerged buoys. Wave-powered desalination plants began operating on Garden Island in Western Australia in 2013 and in Perth in 2015. Membrane distillation uses a temperature difference across a membrane to evaporate vapor from a brine solution and condense pure water on the colder side. The design of the membrane can have
1332-403: Is distillation (i.e., boiling and re- condensation of seawater to leave salt and impurities behind). There are currently two technologies with a large majority of the world's desalination capacity: multi-stage flash distillation and reverse osmosis . Solar distillation mimics the natural water cycle, in which the sun heats sea water enough for evaporation to occur. After evaporation,
1406-594: Is a process that removes mineral components from saline water . More generally, desalination is the removal of salts and minerals from a substance. One example is soil desalination . This is important for agriculture. It is possible to desalinate saltwater, especially sea water , to produce water for human consumption or irrigation. The by-product of the desalination process is brine . Many seagoing ships and submarines use desalination. Modern interest in desalination mostly focuses on cost-effective provision of fresh water for human use. Along with recycled wastewater , it
1480-451: Is an artificial process by which saline water (generally sea water ) is converted to fresh water. The most common desalination processes are distillation and reverse osmosis . There are several methods. Each has advantages and disadvantages but all are useful. The methods can be divided into membrane-based (e.g., reverse osmosis ) and thermal-based (e.g., multistage flash distillation ) methods. The traditional process of desalination
1554-548: Is an osmotic pressure gradient, such as a "draw" solution of high concentration. Freeze–thaw desalination (or freezing desalination) uses freezing to remove fresh water from salt water. Salt water is sprayed during freezing conditions into a pad where an ice-pile builds up. When seasonal conditions warm, naturally desalinated melt water is recovered. This technique relies on extended periods of natural sub-freezing conditions. A different freeze–thaw method, not weather dependent and invented by Alexander Zarchin , freezes seawater in
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#17330862082671628-1024: Is commonly a synonym for sewage (also called domestic wastewater or municipal wastewater), which is wastewater that is produced by a community of people. As a generic term, wastewater may also describe water containing contaminants accumulated in other settings, such as: Fresh water Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids . The term excludes seawater and brackish water , but it does include non-salty mineral-rich waters , such as chalybeate springs. Fresh water may encompass frozen and meltwater in ice sheets , ice caps , glaciers , snowfields and icebergs , natural precipitations such as rainfall , snowfall , hail / sleet and graupel , and surface runoffs that form inland bodies of water such as wetlands , ponds , lakes , rivers , streams , as well as groundwater contained in aquifers , subterranean rivers and lakes . Water
1702-449: Is consumed through human activities than is naturally restored, this may result in reduced fresh water availability (or water scarcity ) from surface and underground sources and can cause serious damage to surrounding and associated environments. Water pollution also reduces the availability of fresh water. Where available water resources are scarce, humans have developed technologies like desalination and wastewater recycling to stretch
1776-416: Is critical to the survival of all living organisms . Many organisms can thrive on salt water, but the great majority of vascular plants and most insects , amphibians , reptiles , mammals and birds need fresh water to survive. Fresh water is the water resource that is of the most and immediate use to humans. Fresh water is not always potable water , that is, water safe to drink by humans . Much of
1850-418: Is currently expensive compared to most alternative sources of water, and only a very small fraction of total human use is satisfied by desalination. It is usually only economically practical for high-valued uses (such as household and industrial uses) in arid areas. However, there is growth in desalination for agricultural use and highly populated areas such as Singapore or California. The most extensive use
1924-425: Is expected that costs will continue to decrease with technology improvements that include, but are not limited to, improved efficiency, reduction in plant footprint, improvements to plant operation and optimization, more effective feed pretreatment, and lower cost energy sources. Reverse osmosis uses a thin-film composite membrane, which comprises an ultra-thin, aromatic polyamide thin-film. This polyamide film gives
1998-452: Is extracted for human consumption. Agriculture uses roughly two thirds of all fresh water extracted from the environment. Fresh water is a renewable and variable, but finite natural resource . Fresh water is replenished through the process of the natural water cycle , in which water from seas, lakes, forests, land, rivers and reservoirs evaporates, forms clouds , and returns inland as precipitation. Locally, however, if more fresh water
2072-498: Is in the Persian Gulf . While noting costs are falling, and generally positive about the technology for affluent areas in proximity to oceans, a 2005 study argued, "Desalinated water may be a solution for some water-stress regions, but not for places that are poor, deep in the interior of a continent, or at high elevation. Unfortunately, that includes some of the places with the biggest water problems.", and, "Indeed, one needs to lift
2146-407: Is more cost effective if kept at a small scale. Wave powered desalination systems generally convert mechanical wave motion directly to hydraulic power for reverse osmosis. Such systems aim to maximize efficiency and reduce costs by avoiding conversion to electricity, minimizing excess pressurization above the osmotic pressure, and innovating on hydraulic and wave power components. One such example
2220-493: Is most suitable for large scale desert greening as it has a km footprint for the water distillation and the same for landscape transformation in desert greening, respectively the regeneration of natural fresh water cycles. In vacuum distillation atmospheric pressure is reduced, thus lowering the temperature required to evaporate the water. Liquids boil when the vapor pressure equals the ambient pressure and vapor pressure increases with temperature. Effectively, liquids boil at
2294-417: Is one of the few water resources independent of rainfall. Due to its energy consumption, desalinating sea water is generally more costly than fresh water from surface water or groundwater , water recycling and water conservation ; however, these alternatives are not always available and depletion of reserves is a critical problem worldwide. Desalination processes are using either thermal methods (in
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2368-479: Is particularly crucial in Africa, where water resources are often scarce and climate change poses significant challenges. Saline water in oceans , seas and saline groundwater make up about 97% of all the water on Earth . Only 2.5–2.75% is fresh water, including 1.75–2% frozen in glaciers , ice and snow, 0.5–0.75% as fresh groundwater. The water table is the level below which all spaces are filled with water, while
2442-826: Is securing minimum streamflow , especially preserving and restoring instream water allocations . Fresh water is an important natural resource necessary for the survival of all ecosystems . Water pollution (or aquatic pollution) is the contamination of water bodies , with a negative impact on their uses. It is usually a result of human activities. Water bodies include lakes , rivers , oceans , aquifers , reservoirs and groundwater . Water pollution results when contaminants mix with these water bodies. Contaminants can come from one of four main sources. These are sewage discharges, industrial activities, agricultural activities, and urban runoff including stormwater . Water pollution may affect either surface water or groundwater . This form of pollution can lead to many problems. One
2516-420: Is the degradation of aquatic ecosystems . Another is spreading water-borne diseases when people use polluted water for drinking or irrigation . Water pollution also reduces the ecosystem services such as drinking water provided by the water resource . Uses of water include agricultural , industrial , household , recreational and environmental activities. The Sustainable Development Goals are
2590-449: Is the most thermodynamically efficient among methods powered by heat, a few limitations exist such as a max temperature and max number of effects. Vapor-compression evaporation involves using either a mechanical compressor or a jet stream to compress the vapor present above the liquid. The compressed vapor is then used to provide the heat needed for the evaporation of the rest of the sea water. Since this system only requires power, it
2664-531: The Amazon River . The atmosphere contains 0.04% water. In areas with no fresh water on the ground surface, fresh water derived from precipitation may, because of its lower density, overlie saline ground water in lenses or layers. Most of the world's fresh water is frozen in ice sheets . Many areas have very little fresh water, such as deserts . Water is a critical issue for the survival of all living organisms. Some can use salt water but many organisms including
2738-657: The Green Sahara periods) and are not appreciably replenished under current climatic conditions - at least compared to drawdown, these aquifers form essentially non-renewable resources comparable to peat or lignite, which are also continuously formed in the current era but orders of magnitude slower than they are mined. Fresh water can be defined as water with less than 500 parts per million (ppm) of dissolved salts . Other sources give higher upper salinity limits for fresh water, e.g. 1,000 ppm or 3,000 ppm. Fresh water habitats are classified as either lentic systems , which are
2812-730: The Middle Ages , but desalination became feasible on a large scale only in the modern era. A good example of this experimentation comes from Leonardo da Vinci (Florence, 1452), who realized that distilled water could be made cheaply in large quantities by adapting a still to a cookstove. During the Middle Ages elsewhere in Central Europe, work continued on distillation refinements, although not necessarily directed towards desalination. The first major land-based desalination plant may have been installed under emergency conditions on an island off
2886-656: The South Seas , reported that he had been able to supply his men with fresh water by means of shipboard distillation. Additionally, during the early 1600s, several prominent figures of the era such as Francis Bacon and Walter Raleigh published reports on desalination. These reports and others, set the climate for the first patent dispute concerning desalination apparatus. The two first patents regarding water desalination were approved in 1675 and 1683 (patents No. 184 and No. 226, published by William Walcot and Robert Fitzgerald (and others), respectively). Nevertheless, neither of
2960-508: The earth 's fresh water (on the surface and groundwater) is to a substantial degree unsuitable for human consumption without treatment . Fresh water can easily become polluted by human activities or due to naturally occurring processes, such as erosion. Fresh water makes up less than 3% of the world's water resources, and just 1% of that is readily available. About 70% of the world's freshwater reserves are frozen in Antarctica . Just 3% of it
3034-457: The 1500s, and formulated practical advice that was publicized to all U.S. ships on the reverse side of sailing clearance permits. Beginning about 1800, things started changing as a consequence of the appearance of the steam engine and the so-called age of steam . Knowledge of the thermodynamics of steam processes and the need for a pure water source for its use in boilers generated a positive effect regarding distilling systems. Additionally,
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3108-476: The RO membranes are destroyed. To mitigate damage, various pretreatment stages are introduced. Anti-scaling inhibitors include acids and other agents such as the organic polymers polyacrylamide and polymaleic acid , phosphonates and polyphosphates . Inhibitors for fouling are biocides (as oxidants against bacteria and viruses), such as chlorine, ozone, sodium or calcium hypochlorite. At regular intervals, depending on
3182-645: The UAE; and the biggest plant with a volume of 1,401,000 m3/d is in Saudi Arabia (Ras Al Khair). As of 2021 22,000 plants were in operation In 2024 the Catalan government installed a floating offshore plant near the port of Barcelona and purchased 12 mobile desalination units for the northern region of the Costa Brava to combat the severe drought. In 2012, cost averaged $ 0.75 per cubic meter. By 2022, that had declined (before inflation) to $ 0.41. Desalinated supplies are growing at
3256-494: The area above this level, where spaces in the rock and soil contain both air and water, is known as the unsaturated zone. The water in this unsaturated zone is referred to as soil moisture. Below the water table, the entire region is known as the saturated zone, and the water in this zone is called groundwater. Groundwater plays a crucial role as the primary source of water for various purposes including drinking, washing, farming, and manufacturing, and even when not directly used as
3330-421: The available supply further. However, given the high cost (both capital and running costs) and - especially for desalination - energy requirements, those remain mostly niche applications. A non-sustainable alternative is using so-called " fossil water " from underground aquifers . As some of those aquifers formed hundreds of thousands or even millions of years ago when local climates were wetter (e.g. from one of
3404-473: The case of distillation ) or membrane-based methods (e.g. in the case of reverse osmosis ). An estimate in 2018 found that "18,426 desalination plants are in operation in over 150 countries. They produce 87 million cubic meters of clean water each day and supply over 300 million people." The energy intensity has improved: It is now about 3 kWh/m (in 2018), down by a factor of 10 from 20–30 kWh/m in 1970. Nevertheless, desalination represented about 25% of
3478-414: The channel, the researchers were able to achieve NaCL concentration drop of 25000 ppm with a recovery rate of 10% of the original water volume. The desalination process's energy consumption depends on the water's salinity. Brackish water desalination requires less energy than seawater desalination. The energy intensity of seawater desalination has improved: It is now about 3 kWh/m (in 2018), down by
3552-642: The coast of Tunisia in 1560. It is believed that a garrison of 700 Spanish soldiers was besieged by the Turkish army and that, during the siege, the captain in charge fabricated a still capable of producing 40 barrels of fresh water per day, though details of the device have not been reported. Before the Industrial Revolution , desalination was primarily of concern to oceangoing ships, which otherwise needed to keep on board supplies of fresh water. Sir Richard Hawkins (1562–1622), who made extensive travels in
3626-421: The condensation of the water vapor from the previous step. Multiple-effect distillation (MED) works through a series of steps called "effects". Incoming water is sprayed onto pipes which are then heated to generate steam. The steam is then used to heat the next batch of incoming sea water. To increase efficiency, the steam used to heat the sea water can be taken from nearby power plants. Although this method
3700-673: The construction of over 200 electrodialysis and distillation plants globally, reverse osmosis (RO) research, and international cooperation (for example, the First International Water Desalination Symposium and Exposition in 1965). The Office of Saline Water merged into the Office of Water Resources Research in 1974. The first industrial desalination plant in the United States opened in Freeport, Texas in 1961 after
3774-444: The cost of such carbon removal can be paid for in large part if not entirely from the sale of the desalinated water produced as a byproduct. Microbial desalination cells are biological electrochemical systems that implements the use of electro-active bacteria to power desalination of water in situ , resourcing the natural anode and cathode gradient of the electro-active bacteria and thus creating an internal supercapacitor . In
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#17330862082673848-407: The energy consumed by the water sector in 2016. Ancient Greek philosopher Aristotle observed in his work Meteorology that "salt water, when it turns into vapour, becomes sweet and the vapour does not form salt water again when it condenses", and that a fine wax vessel would hold potable water after being submerged long enough in seawater, having acted as a membrane to filter the salt. At
3922-527: The freshwater flow to be measurably contaminated both by insoluble solids but also by the soluble components of those soils. Significant quantities of iron may be transported in this way including the well-documented transfer of iron-rich rainfall falling in Brazil derived from sand-storms in the Sahara in north Africa . In Africa, it was revealed that groundwater controls are complex and do not correspond directly to
3996-547: The great majority of higher plants and most mammals must have access to fresh water to live. Some terrestrial mammals, especially desert rodents , appear to survive without drinking, but they do generate water through the metabolism of cereal seeds, and they also have mechanisms to conserve water to the maximum degree. Freshwater ecosystems are a subset of Earth's aquatic ecosystems . They include lakes , ponds , rivers , streams , springs , bogs , and wetlands . They can be contrasted with marine ecosystems , which have
4070-507: The membrane contamination; fluctuating seawater conditions; or when prompted by monitoring processes, the membranes need to be cleaned, known as emergency or shock-flushing. Flushing is done with inhibitors in a fresh water solution and the system must go offline. This procedure is environmentally risky, since contaminated water is diverted into the ocean without treatment. Sensitive marine habitats can be irreversibly damaged. Off-grid solar-powered desalination units use solar energy to fill
4144-438: The membrane feed side) to preferentially induce water permeation through the membrane while rejecting salts. Reverse osmosis plant membrane systems typically use less energy than thermal desalination processes. Energy cost in desalination processes varies considerably depending on water salinity, plant size and process type. At present the cost of seawater desalination, for example, is higher than traditional water sources, but it
4218-674: The membrane its transport properties, whereas the remainder of the thin-film composite membrane provides mechanical support. The polyamide film is a dense, void-free polymer with a high surface area, allowing for its high water permeability. A recent study has found that the water permeability is primarily governed by the internal nanoscale mass distribution of the polyamide active layer. The reverse osmosis process requires maintenance. Various factors interfere with efficiency: ionic contamination (calcium, magnesium etc.); dissolved organic carbon (DOC); bacteria; viruses; colloids and insoluble particulates; biofouling and scaling . In extreme cases,
4292-398: The number of people suffering from water scarcity ." Another target, Target 15.1, is: "By 2020, ensure the conservation, restoration and sustainable use of terrestrial and inland freshwater ecosystems and their services, in particular forests, wetlands , mountains and drylands , in line with obligations under international agreements." Subnotes Desalination Desalination
4366-413: The others as well. Water scarcity (closely related to water stress or water crisis) is the lack of fresh water resources to meet the standard water demand. There are two types of water scarcity. One is physical. The other is economic water scarcity . Physical water scarcity is where there is not enough water to meet all demands. This includes water needed for ecosystems to function. Regions with
4440-882: The same time the desalination of seawater was recorded in China. Both the Classic of Mountains and Water Seas in the Period of the Warring States and the Theory of the Same Year in the Eastern Han Dynasty mentioned that people found that the bamboo mats used for steaming rice would form a thin outer layer after long use. The as-formed thin film had adsorption and ion exchange functions, which could adsorb salt. Numerous examples of experimentation in desalination appeared throughout Antiquity and
4514-407: The sea and somewhat high, such as Riyadh and Harare . By contrast in other locations transport costs are much less, such as Beijing, Bangkok , Zaragoza , Phoenix , and, of course, coastal cities like Tripoli . After desalination at Jubail , Saudi Arabia, water is pumped 320 km inland to Riyadh . For coastal cities, desalination is increasingly viewed as a competitive choice. In 2023, Israel
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#17330862082674588-421: The sea if windy conditions have lifted drops of seawater into the rain-bearing clouds. This can give rise to elevated concentrations of sodium , chloride , magnesium and sulfate as well as many other compounds in smaller concentrations. In desert areas, or areas with impoverished or dusty soils, rain-bearing winds can pick up sand and dust and this can be deposited elsewhere in precipitation and causing
4662-417: The spread of European colonialism induced a need for freshwater in remote parts of the world, thus creating the appropriate climate for water desalination. In parallel with the development and improvement of systems using steam ( multiple-effect evaporators ), these type of devices quickly demonstrated their desalination potential. In 1852, Alphonse René le Mire de Normandy was issued a British patent for
4736-420: The stillwaters including ponds , lakes, swamps and mires ; lotic which are running-water systems; or groundwaters which flow in rocks and aquifers . There is, in addition, a zone which bridges between groundwater and lotic systems, which is the hyporheic zone , which underlies many larger rivers and can contain substantially more water than is seen in the open channel. It may also be in direct contact with
4810-636: The surface, and soil moisture, and less than 0.01% of it as surface water in lakes , swamps and rivers . Freshwater lakes contain about 87% of this fresh surface water, including 29% in the African Great Lakes , 22% in Lake Baikal in Russia, 21% in the North American Great Lakes , and 14% in other lakes. Swamps have most of the balance with only a small amount in rivers, most notably
4884-469: The time). Freshwater ecosystems contain 41% of the world's known fish species. The increase in the world population and the increase in per capita water use puts increasing strains on the finite resources availability of clean fresh water. The response by freshwater ecosystems to a changing climate can be described in terms of three interrelated components: water quality, water quantity or volume, and water timing. A change in one often leads to shifts in
4958-440: The two inventions entered service as a consequence of scale-up difficulties. No significant improvements to the basic seawater distillation process were made during the 150 years from the mid-1600s until 1800. When the frigate Protector was sold to Denmark in the 1780s (as the ship Hussaren ) its still was studied and recorded in great detail. In the United States, Thomas Jefferson catalogued heat-based methods going back to
5032-657: The underlying underground water. The original source of almost all fresh water is precipitation from the atmosphere , in the form of mist , rain and snow . Fresh water falling as mist, rain or snow contains materials dissolved from the atmosphere and material from the sea and land over which the rain bearing clouds have traveled. The precipitation leads eventually to the formation of water bodies that humans can use as sources of freshwater: ponds , lakes , rainfall , rivers , streams , and groundwater contained in underground aquifers . In coastal areas fresh water may contain significant concentrations of salts derived from
5106-428: The water by 2000 m, or transport it over more than 1600 km to get transport costs equal to the desalination costs." Thus, it may be more economical to transport fresh water from somewhere else than to desalinate it. In places far from the sea, like New Delhi, or in high places, like Mexico City , transport costs could match desalination costs. Desalinated water is also expensive in places that are both somewhat far from
5180-425: The water vapor is condensed onto a cool surface. There are two types of solar desalination. The first type uses photovoltaic cells to convert solar energy to electrical energy to power desalination. The second type converts solar energy to heat, and is known as solar thermal powered desalination. Water can evaporate through several other physical effects besides solar irradiation . These effects have been included in
5254-461: Was constant recharge with little variation with precipitation; in most sites (arid, semi-arid, humid), annual recharge increased as annual precipitation remained above a certain threshold; and in complex areas down to 0.1 aridity index (focused recharge), there was very inconsistent recharge (low precipitation but high recharge). Understanding these relationships can lead to the development of sustainable strategies for water collection. This understanding
5328-610: Was created in the United States Department of the Interior in 1955 in accordance with the Saline Water Conversion Act of 1952. This act was motivated by a water shortage in California and inland western United States. The Department of the Interior allocated resources including research grants, expert personnel, patent data, and land for experiments to further advancements. The results of these efforts included
5402-585: Was installed at Suakin during the 1880s that provided freshwater to the British troops there. It consisted of six-effect distillers with a capacity of 350 tons/day. After World War II, many technologies were developed or improved such as Multi Effect Flash desalination (MEF) and Multi Stage Flash desalination (MSF). Another notable technology is freeze-thaw desalination. Freeze-thaw desalination, (cryo-desalination or FD), excludes dissolved minerals from saline water through crystallization. The Office of Saline Water
5476-505: Was using desalination to replenish the Sea of Galilee 's water supply. Not everyone is convinced that desalination is or will be economically viable or environmentally sustainable for the foreseeable future. Debbie Cook wrote in 2011 that desalination plants can be energy intensive and costly. Therefore, water-stressed regions might do better to focus on conservation or other water supply solutions than invest in desalination plants. Desalination
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