Sailors and shipbuilders were the first to think about how to desalinate the water of the seas and oceans. Indeed, for sailors, fresh water is the most valuable cargo on board. You can survive during a storm, endure the heavy heat of the tropics, survive separation from the earth, eat corned beef and crackers for months. But what about without water? And hundreds of barrels of ordinary fresh water were loaded into the holds. Paradox! After all, there is an abyss of water overboard. Yes, water, but salty, and to the point where it is 50 to 70 times saltier than drinkable water. It is natural, therefore, that the idea of ​​desalination is as old as the world.

Even the ancient Greek scientist and philosopher Aristotle (384-322 BC) wrote: “Evaporating, salt water forms fresh water ...” The first experience of artificial water desalination recorded in written sources dates back to the 4th century BC.
The legend says that St. Basil, who was shipwrecked and left without water, understood how to save himself and his comrades. He boiled sea water, saturated sea sponges with steam, squeezed them out and got fresh water… Centuries have passed since then and people have learned how to create desalination plants. The history of water desalination in Russia began in 1881. Then, in a fortress on the shores of the Caspian Sea, near present-day Krasnovodsk, a distiller was built to supply the garrison with fresh water. He produced 30 square meters fresh water per day. This is very little! And already in 1967, an installation was created there, which provided 1,200 square meters of water per day. Now more than 30 distillers operate in Russia, their total capacity is 300,000 square meters of fresh water per day.

The first large plants for the production of fresh water from sea appeared, of course, in the desert regions of the world. More precisely - in Kuwait, on the shores of the Persian Gulf. Here is one of the largest oil and gas fields in the world. Since the early 1950s, several seawater desalination plants have been built in Kuwait. A powerful distillation plant in combination with a thermal power plant operates on the island of Aruba in the Caribbean. Now desalinated water is already being used in Algeria, Libya, Bermuda and the Bahamas, and in some parts of the United States. There is a seawater desalination plant in Kazakhstan on the Mangyshlak peninsula. Here, in the desert, in 1967, a man-made oasis grew - the city of Shevchenko. Among its main attractions are not only the world-famous powerful nuclear power plant, a large seawater desalination plant, but also a carefully thought-out water supply system. There are three water lines in the city. One is high-quality fresh drinking water, the second is slightly brackish, it can be washed and watered plants, the third is ordinary sea water used for technical needs, including sewerage.

Water desalination plant nuclear power plant the city of Shevchenko (1982).

More than 120 thousand people live in the city, and each of them has no less water than Muscovites or Kyivans. Enough water and plants. And to drink them is not such a simple matter: an adult tree drinks 5-10 liters per hour. But nevertheless, for every inhabitant there is 45 square meters of green space. This is almost 1.5 times more than in Moscow, 2 times more than in Vienna famous for its parks, about 5 times more than in New York and London, 8 times more than in Paris.

Issues discussed in the material:

• Why is there a need for seawater desalination?
• What are the methods of desalination of sea water
• How to desalinate sea water at home
• What problems are inherent in the process of seawater desalination

Purification and desalination of sea water is an industrial process, as a result of which salts are removed from it and a product suitable for domestic use and consumption is obtained. Our article will tell about the methods and technologies of seawater desalination.

60% of the earth's surface consists of territories where there are either no sources of fresh water at all, or there are, but a very small amount. Since there are few freshwater reservoirs in many arid areas, there are problems with watering the soil. They could be solved thanks to the possibility of using desalinated sea water for these purposes. There are significant reserves of such water on Earth, but due to the high salt content, it cannot be used for economic purposes.

To grow crops, it is necessary to water them with water with a very low salt content. If plants receive more than 0.25% salts with moisture, they simply will not grow. Also, the presence of alkalis in the water will adversely affect them. Many states, including Russia, are looking for ways to desalinate salty water sources, which would help to cope with drought problems in areas located near the sea.

In countries with a well-developed industry, there is an increasingly acute shortage of fresh water reserves. In particular, this applies to the USA and Japan, where the required for industry, Agriculture and household needs, the volumes of water have long exceeded the available ones.

The amount of fresh water does not meet the needs in developed countries with low rainfall, such as Israel and Kuwait.

Russia occupies the first place in the world in terms of terrestrial freshwater resources. Baikal alone is enough to satisfy the current need of the Russian population and industry for fresh water. This lake is so deep that if you direct the flows of all rivers into its basin the globe, then it will be filled for almost 300 days.

However, most of Russia's water resources are concentrated in practically uninhabited and undeveloped areas of Siberia, the North and Far East. To highly developed central and southern regions with high level industry, agriculture and population density account for only 20% of freshwater reserves.

Certain countries Central Asia(Turkmenistan, Kazakhstan), as well as the Caucasus, Donbass and the southeastern part of the Russian Federation, have huge mineral and raw material resources, but they do not have freshwater sources.

In Russia, there are a large number of underground sources, the mineralization level of which ranges from 1 to 35 g/l. They cannot be used for the needs of the population, as they contain a large amount of salts, but after desalination they can be used quite well.

In the process of desalination of sea water, an important parameter is its salinity, which refers to the mass of dry salts in grams per 1 kg of substance. The amount of salts per unit volume of liquid can vary significantly depending on the sea. For example, Black, Caspian and Sea of ​​Azov characterized as slightly salty. The average salinity of the World Ocean is 35g/kg.

Except table salt(NaCl), sea water also contains a number of other chemical elements, mainly in the form of ions that can be obtained from it on an industrial scale: K+, Mg2+, Ca2+, Sr2+, Br-, F-, H3BO3. In total, about 50 chemical elements in various concentrations have been found in the subsoil of the sea, including lithium (Li), rubidium (Rb), phosphorus (P), iodine (J), iron (Fe), zinc (Zn) and molybdenum (Mo).

Marine water resources contain more than 50 chemical elements. The concentration of each of them is extremely small, but their total mass determines the salinity of the liquid. Only water containing no more than 0.001 g / ml of salts can be suitable for food. In order to achieve such a concentration, various seawater desalination technologies are used. Specialists are trying to develop desalination systems that would consume little energy, but at the same time purify water as much as possible for use by the population.

Today, the following methods of seawater desalination are used: distillation, reverse osmosis, ionization and electrodialysis.

In the southern regions, solar distillers are actively used, in which sea water is heated and evaporated. There is also an opposite method, in which salt water is frozen and then fresh water is separated from it, since it freezes faster.

A sea water maker is a device that can remove salts dissolved in water from water. After the purification procedure, water is obtained, which can be used not only for household needs, but also for drinking. The design of the device is distinguished by convenience and practicality in operation.

However, desalinated water is not clean at the same time, because other components are also preserved in it, the density of which determines the area of ​​its application. So, on sea vessels, different types water reserves:

• drinking, which is used only for cooking and drinking;
• water for personal hygiene and deck washing;
• water for steam generators, or feed water;
• technical water, which is used as a coolant for engines;
• distilled water.

To obtain all these types, different ship distillers are used.

Desalination technologies include the following:

1. Distillation, in which the desalinator heats and evaporates sea water. The resulting steam is "caught" and brought to the required temperature.
2. Filtration, in which the device works on the principle of reverse osmosis. Salt water is purified without going from one state to another. The operation of such an apparatus is based on bringing the concentration of dissolved impurities to the optimum. Very high pressure allows you to "squeeze out" excess salt particles.

In the Israeli city of Hadera, there is the largest distiller on the planet. This unit is commensurate in size with the whole plant. Every year it desalinates about thirty-three billion gallons of sea water. The distiller works on the principle of reverse osmosis, as a result of which the Mediterranean waters are not subjected to heat treatment.

The installation is completely hermetic, it creates the effect of a greenhouse, while no leakage of fumes to the outside is allowed. As a result, the net water residue is retained in a larger volume. At the end, the cork is unscrewed, and the purified liquid is drained into a container.

Similar devices are used in navy. They use the heat of the liquid, which serves to cool the main and auxiliary diesels. Purified water, heated to 60 °C, enters at the inlet through the pipes of the heating battery. When leaving the liquid, the temperature of the liquid drops to about 10 °C.

Vacuum maker produces about 800 liters of distilled water per hour. It can meet all the demand for fresh water without wasting fuel energy, and full automation saves on after-sales service. Since the evaporation temperature is quite low, the water maker can operate for six to twelve months without requiring cleaning.

It is known that the population of Israel suffers from a serious shortage of drinking supplies. The operation of the apparatus described above makes it possible to cover almost two-thirds of the water demand of the whole country.

Today, a variety of equipment is used to desalinate seawater, including unique solar-powered desalination plants. Water is poured into them, which, under the influence of solar heat, turns into steam, condenses on the walls of the case and then settles in the lower part of the device.

To date, two methods of desalination are widely used in industry: membrane (mechanical) and thermal (distillation). In the first case, reverse osmosis technology is used. Sea water is passed through semi-impermeable membranes under a pressure significantly exceeding the pressure difference between fresh and sea water (for the latter it is 25-50 atm.).

The microscopic pores of the filters freely pass only small water molecules, retaining larger ions of salt and other impurities. The material for such membranes is polyamide or cellulose acetate, they are produced in the form of hollow fibers or rolls.

The method of deep reverse osmosis water desalination has a number of advantages compared to other methods. Firstly, the devices are simple and compact, and secondly, they do not require large amounts of energy. In addition, the reverse osmosis system is controlled in semi-automatic and automatic modes.

However, this method also has its drawbacks. The quality of cleaning here depends on how effective the pre-treatment was. In addition, the resulting drinking water still contains a fairly large amount of salt (500 mg/m3 of total salt concentration). Also, this method requires increased operating costs, since the regular purchase of associated chemicals and the replacement of membrane filters are necessary.

Wonthaggi Desalination Plant is the world's largest membrane filter desalination plant located in Melbourne. It is capable of processing 440 thousand cubic meters of water per day. In the Israeli city of Ashkelon, there is a plant where water is purified from salts by reverse osmosis. It processes 330 thousand cubic meters of water per day.

The essence of the thermal method (distillation) is that liquid is boiled at the seawater desalination station, and the resulting steam is accumulated and condensed. This forms a distillate - fresh water. You can also boil water without bringing it to a boil. In this case, it is heated at a higher pressure than in the evaporation chamber. The heat of the water itself is used to form steam. At the same time, it is cooled to the saturation temperature of the remaining brine. The disadvantages of this method are the cost, high energy intensity, and the presence of an external source of steam. However, it is he who gives the largest volume of fresh water per unit of time. For example, the Shoaiba 3 plant (Saudi Arabia) produces up to 880 thousand cubic meters of fresh water per day using the distillation method.

The two methods can be compared in several key ways:

Options	Reverse osmosis	thermal method
Physico-chemical principle	Membrane diffusion	Thermal evaporation and condensation
Energy Consumption (Including the consumption of auxiliary devices)	Electricity: 3.5-4.5 kWh/m3	Electricity: 2.5-5 kWh/m3, thermal 40-120 kWh/m3
The highest temperature in the desalination process	sea ​​water temperature
Water quality (salt content mg/l)
Average productivity of one desalination module	6000-24000 m3/day	120000 m3/day
Main Devices	Pumps, diaphragms	Pumps, valves, vacuum systems
total cost
Level of production automation
Ability to change the composition of sea water		medium-high
Maintenance Requirements
Scaling Potential		Medium-low
Space Requirements
Most Needed Improvements	Improvement of water pre-treatment, improvement of membrane properties	Cheaper materials and heat transfer methods

Difficulties with fresh water supply arose in Crimea after the well-known events in 2014. Then Ukraine blocked the channel through which fresh water was supplied to the peninsula, resulting in a shortage of technical and drinking water reserves.

There is information about the planned installation of a desalination system in Kerch, which will produce about 50 tons of water per hour. Water resources purified from salts will be used mainly for technical needs: feeding heating networks and steam boilers. This will help reduce the burden on the public water supply.

Water purification at this plant will take place in several stages. For clarification, it is supposed to use a combined membrane technology, for purification from salts - a reverse osmosis method, for polishing softening - an ion-exchange method.

The system will work in automatic mode, only one operator is needed to control the process.

Today, the profitability of watering desalinated crops sea ​​water is a big question: unfortunately, existing technologies do not allow obtaining both high-quality and cheap fresh water from salt water at the same time. But different countries of the world are constantly working in this direction, because ecological problems desalination of sea water concerns all mankind and requires permission.

Scientists have high hopes for use to clean up water resources atomic energy, which would make desalination technologies much cheaper.

Do-it-yourself seawater desalination at home and in extreme conditions

If you need to purify sea water from salts during a hike, a home-made distiller is best suited for this, similar in design to well-known distillation apparatus.

The essence of the process in a conventional desalination plant is as follows: the salty liquid is heated to a boil, then the resulting steam is accumulated in a container and cooled. After the procedure, chilled droplets of water, purified from salt impurities, settle on the walls of the chamber.

Salts stand out from the mixture because the boiling point at brine slightly higher than pure water. Therefore, the fresh component evaporates faster and settles into the collection container.

To desalinate sea water in field conditions, you will need:

• first of all - the water itself, which is always in abundance on the coast of the sea or a salt lake;
• a kettle or kettle as a container for heating;
• an aluminum tube, which should be prepared before the start of the trip;
• a deep hole dug in the sand: it will serve as a cooling device;
• another container (glass bottle, stainless steel jar, etc.), where water purified from impurities will be collected.

On the shore of a lake or sea, you should dig a hole up to a meter deep, place a container (bottle) in it at a slight angle, into the neck of which you need to insert a tube.

Prepare a rubber gasket in advance: with its help, you will securely seal the junction of the aluminum tube with the neck of the bottle.

Then the structure should be covered with sand in such a way that only the upper part of the neck with the inserted tube remains open. The end of the tube will need to be placed over a kettle or open kettle of sea water. In this case, the fire is bred at a small distance from the bottle with the tube.

After the fire flares up, the water in the container will warm up and begin to boil, and the steam will gradually spread through the tube into a bottle buried in the sand, where it will settle like condensate. Gradually, up to 200-300 grams of pure fresh liquid is formed at the bottom of the container.

by the most in a simple way to purify water from salt at home is the use of a system consisting of a number of filters connected in a certain sequence. But even a complex multi-stage combination cannot remove absolutely all harmful impurities from the water. Therefore, long-known home desalination methods are very popular among the people.

For example, water is poured into a bottle and placed in a freezer, where after a while the pure component freezes. The part that does not freeze just contains all the harmful impurities, so it is drained. The frozen water residue, when it melts at room temperature, can be used for drinking and other needs.

There are two more ways to purify salt from water that can be easily implemented at home. The first is long boiling, as a result of which salt settles on the walls in the form of scale. The second is activated carbon filtration. In this case, the amount of material used will depend on the salt concentration.

Today, of all desalination methods, reverse osmosis technology is the most in demand. But its use requires high costs for the production and operation of membranes, as well as significant energy capacities. In addition, after desalination in this way, a highly concentrated salt solution remains, which is returned to the sea or ocean, which increases the salinity of water resources. Because of this, the purification process becomes even more complicated, and the cost of seawater desalination only increases every year.

In addition, only 1/3 of the world's freshwater resources are in the soil (2/3 are frozen in snow covers and glaciers). And they are used by man so quickly that nature does not have time to make up for the lost.

In this regard, the scarcity of fresh water is increasing on a global scale.

Experts predict that by 2030 more than two billion people will experience water shortages. This problem is exacerbated by the fact that each country uses different volumes of fresh water.

For example, an American consumes on average about 400 liters per day, while a resident of an underdeveloped country consumes only 19 liters. Half of the world's population does not have running water at all in their homes. All this will one day lead people to pay special attention to the oceans as sources of water.

The main challenge in seawater desalination is to minimize energy and equipment costs. This is especially important because a country that needs more purified water must also withstand economic competition with countries that have cheaper and more abundant freshwater sources.

According to the results of design development, it turns out that only for a small number of consumers it will be cheaper to transport water from a natural reservoir over a distance of 400-500 km than to desalinate it. Estimating underground reserves of varying degrees of salinity in arid regions, we can conclude that desalination is the only economically viable way of water supply for them, given their remoteness from freshwater sources of natural origin.

The desalination methods used today can be productively used to return used water resources to nature without worsening the condition of fresh water bodies.

If the water quality leaves much to be desired…

The problem of dirty water in the house can be partially solved by installing a high-quality filter, but in such systems it is periodically necessary to replace components, because it directly depends on how well the drinking liquid will be cleaned.

At the same time, the question remains unresolved: how to ensure that our workplace or the child at school has water. best quality? The best solution is to buy it with delivery.

The Iceberg company offers favorable conditions for servicing its customers:

• free delivery of water to your home or office: buyers pay only the cost of the goods;
• wells from which our water is drawn have registration documents in the State Water Cadastre of the Russian Federation;
• for the extraction and bottling of water, advanced technologies are used, which helps to preserve and increase its quality and natural purity;
• we also sell modern water coolers and other equipment manufactured by well-known European brands, taking into account existing quality standards. The sizes of pumps and racks for bottles vary, allowing you to install devices even in small rooms;
• delivery drinking water to your home or office is carried out at the lowest price, thanks to constant promotions from our company;
• along with water, you can purchase disposable tableware, tea, coffee and other auxiliary products.

Clean water is valuable, but it should not be worth its weight in gold. Our mission is to provide every home and workplace high-quality drinking water, so we have prepared the most favorable conditions for our customers.

Today, the problem of drinking water is becoming more and more urgent in the world - it is quite scarce. Africa, for example, is provided with this resource by only 30 percent of the required amount.

Other countries to this mainland carried outdrinking water deliverypossible, but this is still not enough. It was this situation that prompted scientists to think about whether it is possible to make drinking water out of sea water? In fact, perhaps even at home, although this is a long process. This will require a distillation cube or a moonshine still. In this case, the law of physics is used, according to which salts cannot completely dissolve in water. That is, after evaporation, the minerals remain at the bottom.

sea ​​water sweep

Having driven sea water through the moonshine still, after boiling it, you will get ready-to-drink drinking water with a minimum amount of impurities. In its composition, it is more like distilled water, which does not conduct electricity. Therefore, it is quite difficult to get drunk on it. But pharmacies sell the so-called "enrichers", adding just a few drops of them, you can get the water that the human body needs. So, in total, the production of drinking water from sea water costs a little more than the production of mineral water.

How to make drinking water from sea water in natural conditions?

It is not difficult to turn sea water into drinking water if you create a kind of moonshine from improvised means. This will require a hole, which is wrapped inside with a film, several large stones and hay. Water poured into the hole is covered with hay. Stones are placed on top, which are also covered with a film. After the water heats up, it will begin to evaporate, and when it becomes cool, it will condense on the stones. Of course, there will be very little water, but enough to at least quench your thirst.

Water is vital for every person on the planet. Unfortunately, it is not available to everyone. But a new invention developed by a research group at the University of Alexandria in Egypt could change that.

Operating principle

The technology uses a desalination technique called pervaporation. Salt is removed from seawater using specially designed synthetic membranes that filter out coarse salt particles and impurities. The remaining salt is heated, evaporated, and then condenses back into pure water.

In developing countries, investing time and money in the development of water filtration technologies is critical. However, the technology must be accessible and easily reproducible. Fortunately, the membranes involved in this new invention can be made in any laboratory. They can be made from inexpensive materials available locally. More importantly, the evaporation process does not require electricity, which makes this method of drinking water treatment cheap and suitable for areas where there is no electricity supply.

In addition, the researchers found another interesting feature this technique. It is able not only to filter out salts, but to remove other pollutants.

Efficiency

According to Helmi El-Zanfali, a professor at the National Research Center in Egypt, the technology implemented in the study is much better than the reverse osmosis technologies currently used in both Egypt and the Middle East and North Africa. Using this development, it is possible to effectively desalinate water containing high concentrations of salt in the Red Sea, where desalination is more expensive.

At the moment, the technology is not yet ready for domestic use. The development has been proven in theory to be effective, but large-scale demonstrations and action plans have yet to be made to deal with the waste.

One of the most important problems modern world is the shortage of drinking water. The issue of its shortage is relevant for almost all countries and continents. The essence of the task is not the extraction or delivery of fresh water, but its production from salt water (https://reactor.space/government/desalination/) .

Relevance of the problem

If the water contains up to one gram of salt per liter, it is already suitable for consumption in limited quantities. However, if this indicator approaches the ratio of ten grams per liter, such a liquid can no longer be drunk. There are also a number of restrictions for drinking water regarding the content of microorganisms and organic components in it. Thus, obtaining a pure liquid is a rather complex multilevel process.

The most popular way to obtain drinking water is desalination. Moreover, this method is relevant not only for regions with an arid climate, but also for Europe and America. Making fresh water from salt water is The best way problem solving.

A variety of fluid deposits with a high salt content can be found in almost any region of the planet. There are no conditions for the reproduction of microorganisms. The brines lie at a relatively large depth, which excludes the occurrence of external pollution by hazardous chemical elements. You can also get fresh water from sea water. In this article, we will look at the most popular ways to solve this problem.

Distillation of water by boiling

This technique has been used since ancient times. There are several types of distillation in use today. The bottom line is to bring the liquid to a boil, and condense the vapor. The result is desalinated water.

Two popular technologies are used to produce a liquid in a significant volume. One of them is called multi-column distillation. The essence of the technology is to bring the liquid to a state of boiling in the first column. The resulting steam is used to transfer heat to the rest of the columns. This technique is effective. With its help, you can get fresh water on an industrial scale. However, this technology is very energy intensive. Therefore, in our time it is used quite rarely.

Flash distillation has been found to be more efficient. The essence of the technology is the evaporation of salty liquid in special chambers. In them, the pressure indicator is gradually reduced. Accordingly, to obtain water vapor, a lower temperature indicator is needed. That is why this technology is more efficient.

There are two more methods of distillation: membrane and compression. They arose as a result of the modernization of the first two technologies. Membrane distillation is based on the use of a hydrophobic type membrane that acts as a cooling coil. It retains water while letting steam through. Compressive distillation is based on the use of compressed (superheated) steam in the first column.

All of these technologies have the same drawback. They are too energy intensive. It takes four hundred and twenty kilojoules to heat a liquid from zero to one hundred degrees. And to change the state of water from liquid to gaseous, it will already take two thousand two hundred and sixty kilojoules. Equipment operating on the principle of the considered technologies consumes three and a half or more kilowatts per hour per cubic meter the resulting desalinated liquid.

Distillation by the sun

IN southern countries solar energy is used to carry out the distillation process. This allows you to significantly reduce the cost of desalination of salt water. To perform the distillation process, you can use solar panels or directly thermal energy from the Sun. The simplest in technical terms is the technology based on evaporators. The latter are special prisms made of glass or plastic into which salty liquid is poured.

As a result, solar energy raises the temperature of the water. The liquid begins to evaporate and precipitates in the form of condensate on the walls. The drops emerging from the steam flow into special receivers. As you can see, the technology is very simple. Of its minuses, it is worth highlighting the low rate of efficiency. It does not exceed fifty percent. Therefore, this technology is used only in poor regions. With its help, it is possible to provide fresh water at best to a small village.

Many engineers continue to work on modernizing the considered technology. Their main goal is to increase the output of such systems. For example, the use of capillary films can significantly improve the performance of solar distillers.

We note that systems operating at the expense of alternative sources energy is not the main tool in obtaining fresh water. Although, their use does not require significant costs for the distillation process.

Other technical solutions can be used to remove salts from the liquid. A fairly popular method of water purification is electrodialysis. To implement the method, a pair of membranes is used. One of them is necessary for the passage of cations, and the second is used exclusively for anions. Particles are distributed over the membranes under the influence of direct current. Such a solution is often implemented in conjunction with solar and wind generators.

Reverse osmosis

Water desalination technologies are constantly improving. Reverse osmosis is becoming more and more popular these days. The bottom line is the use of a semi-permeable membrane. A saline liquid passes through it. As a result, particles of salt impurities remain on the side where the pressure indicator is excessive.

The reverse osmosis method is the most economical. Especially if it is used for desalination of water with non-critical salt content. In this case, one kilowatt-hour of energy can be enough to produce one cubic meter of water. Therefore, reverse osmosis technology is considered the most promising.

Results

Each water desalination method has its own characteristics. To produce fresh water on an industrial scale, it is necessary to select the most economical and efficient option. The reverse osmosis method is by far the most effective.