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60-470: Lhünzhub has jurisdiction over six villages, with a population of 7349 people, all ethnic Tibetan. The economy is dominated by agriculture and animal husbandry. There are 27,640 acres (11,190 ha) of arable land producing barley, wheat, rape and other crops. The town has a primary school and a clinic. There is a small hydropower station. The town lies on the Pengbo River . The average temperature

120-524: 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 the coast of Tunisia in 1560. It is believed that a garrison of 700 Spanish soldiers was besieged by

180-535: 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

240-502: 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

300-479: 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

360-701: 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

420-843: 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 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

480-633: 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

540-434: 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

600-486: 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

660-418: 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

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720-550: 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 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

780-492: 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

840-487: 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

900-524: 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

960-403: 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,

1020-479: Is 6.9 °C (44.4 °F) and the average annual precipitation is 414 millimetres (16.3 in). January is the driest month, with no rainfall, and August is the wettest with an average of 122 millimetres (4.8 in). This Lhasa , Tibet location article is a stub . You can help Misplaced Pages by expanding it . Arable land Arable land (from the Latin : arabilis , "able to be ploughed ")

1080-451: 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

1140-403: Is an open-air none recycled water hydroponics relationship. The below described circumstances are not in perspective, have limited duration, and have a tendency to accumulate trace materials in soil that either there or elsewhere cause deoxygenation. The use of vast amounts of fertilizer may have unintended consequences for the environment by devastating rivers, waterways, and river endings through

1200-548: 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

1260-476: Is any land capable of being ploughed and used to grow crops. Alternatively, for the purposes of agricultural statistics, the term often has a more precise definition: Arable land is the land under temporary agricultural crops (multiple-cropped areas are counted only once), temporary meadows for mowing or pasture , land under market and kitchen gardens and land temporarily fallow (less than five years). The abandoned land resulting from shifting cultivation

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1320-418: 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

1380-425: 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

1440-636: 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 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

1500-504: 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

1560-407: 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

1620-493: 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

1680-462: Is not arable according to the FAO definition above includes: Other non-arable land includes land that is not suitable for any agricultural use. Land that is not arable, in the sense of lacking capability or suitability for cultivation for crop production, has one or more limitations – a lack of sufficient freshwater for irrigation, stoniness, steepness, adverse climate, excessive wetness with

1740-574: Is not included in this category. Data for 'Arable land' are not meant to indicate the amount of land that is potentially cultivable. A more concise definition appearing in the Eurostat glossary similarly refers to actual rather than potential uses: "land worked (ploughed or tilled) regularly, generally under a system of crop rotation ". In Britain, arable land has traditionally been contrasted with pasturable land such as heaths , which could be used for sheep-rearing but not as farmland . Arable land

1800-400: 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 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

1860-487: 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 is one of the few water resources independent of rainfall. Due to its energy consumption, desalinating sea water

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1920-434: Is the seawater greenhouse , which desalinates water through evaporation and condensation using solar energy as the only energy input. This technology is optimized to grow crops on desert land close to the sea. The use of artifices does not make the land arable. Rock still remains rock, and shallow – less than 6 feet (1.8 metres) – turnable soil is still not considered toilable. The use of artifice

1980-449: 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

2040-416: Is unsuitable for cultivation, yet such land has value for grazing of livestock. In British Columbia, Canada, 41 percent of the provincial Agricultural Land Reserve area is unsuitable for the production of cultivated crops, but is suitable for uncultivated production of forage usable by grazing livestock. Similar examples can be found in many rangeland areas elsewhere. Land incapable of being cultivated for

2100-558: Is vulnerable to land degradation and some types of un-arable land can be enriched to create useful land. Climate change and biodiversity loss , are driving pressure on arable land. According to the Food and Agriculture Organization of the United Nations, in 2013, the world's arable land amounted to 1.407 billion hectares, out of a total of 4.924 billion hectares of land used for agriculture. Agricultural land that

2160-662: 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

2220-457: 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,

2280-479: 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

2340-551: 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

2400-659: 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

2460-437: The accumulation of non-degradable toxins and nitrogen-bearing molecules that remove oxygen and cause non-aerobic processes to form. Examples of infertile non-arable land being turned into fertile arable land include: One of the impacts of land degradation is that it can diminish the natural capacity of the land to store and filter water leading to water scarcity . Human-induced land degradation and water scarcity are increasing

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2520-414: 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

2580-421: 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

2640-707: 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

2700-444: 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

2760-436: The desert, hydroponics , fertilizer, nitrogen fertilizer, pesticides , reverse osmosis water processors, PET film insulation or other insulation against heat and cold, digging ditches and hills for protection against the wind, and installing greenhouses with internal light and heat for protection against the cold outside and to provide light in cloudy areas. Such modifications are often prohibitively expensive. An alternative

2820-405: The impracticality of drainage, excessive salts, or a combination of these, among others. Although such limitations may preclude cultivation, and some will in some cases preclude any agricultural use, large areas unsuitable for cultivation may still be agriculturally productive. For example, United States NRCS statistics indicate that about 59 percent of US non-federal pasture and unforested rangeland

2880-414: The levels of risk for agricultural production and ecosystem services. Examples of fertile arable land being turned into infertile land include: Desalination Desalination 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

2940-507: 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

3000-438: 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

3060-674: 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,

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3120-402: The production of crops can sometimes be converted to arable land. New arable land makes more food and can reduce starvation . This outcome also makes a country more self-sufficient and politically independent, because food importation is reduced. Making non-arable land arable often involves digging new irrigation canals and new wells, aqueducts, desalination plants, planting trees for shade in

3180-407: 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

3240-417: 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

3300-440: 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

3360-428: 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

3420-425: 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

3480-636: 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

3540-590: 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

3600-508: 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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