Desalination of sea water: technologies of the modern world. How to make fresh water from sea water? How to get fresh water from salt water

People have long figured out how to desalinate sea water in the absence of access to potable water, because potable moisture is the basis for the existence of a living organism.

Today it is possible to obtain desalinated sea water different ways and in different conditions - industrial, domestic and even extreme. Such skills will allow you to quench the pangs of thirst when fresh drinking water is unattainable for some reason.

Existing water desalination methods

In some regions of the planet, the shortage of fresh water is most noticeable - usually in arid landscapes. In such areas, industrial desalination is used.

At home, the production of desalinated water from salt water is forced by difficult living conditions, temporary or permanent, when the population experiences an acute shortage of potable moisture.

The skills of how to make drinking water, having only sea water, have more than once saved lives in conditions natural disasters, fishermen lost at sea, as well as extreme travelers.

• Methods of industrial desalination - chemical using reagents, industrial distillation in a distiller, ionic using an installation and an ion exchanger, reverse osmosis through membrane filters, electrodialysis and industrial freezing;
• Home desalination methods are distillation and partial freezing;
• Extreme desalination methods include collecting condensate using fire or the sun, as well as melting fresh ice.

Desalination methods in industrial scale not our topic, but we will describe in more detail the options for how to get completely drinkable moisture at home or in nature - they may be useful.

Desalination of water at home

At home there is always a source of fire or heat, dishes and devices that are useful for turning sea water into desalinated distillate; in extreme cases, there is a freezer.

The best way to distill seawater into distillate is a household moonshine still if there is a source of fire, but a hastily made analogue will also work. The task is:

• cause sea water to evaporate abundantly from heating;
• remove collected condensate;
• Cooling the steam drops, collect them in a separate container.

Any utensil that can be placed on fire is suitable as a substitute for a moonshine coil. Sea liquid is poured into it, then the vessel is covered with a lid with a hole into which a steam outlet tube is inserted. All that remains is to put a plastic hose on the tube, lower its tip into the container where fresh water will accumulate, and cover it with a wet rag so that the steam cools faster.

Sometimes during a disaster, the surviving housing has no water, no gas, no electricity, but there is some water that is undrinkable. In this case, there are 2 options not to die of thirst.

Option #1.

• The starting liquid is poured into a plastic bottle.
• Its level should be such that it does not reach the neck of the bottle if it is laid flat.
• The neck of the bottle with the original liquid is connected to the neck of the empty bottle using tape.
• The structure is placed flat in the warmest place found in the house - for example, a radiator or a sun-filled window sill.
• Place any object under the empty bottle so that it is slightly higher than the bottle with liquid.
• Soon drops of evaporated condensate will accumulate at the top of the empty bottle and flow down.
• All you have to do is cut the tape and separate the containers - the empty one will contain drinkable water.

Option #2.

• We will need a small basin with high walls.
• Place a small container in the center (a simple glass will do).
• Water for desalination is poured into the basin; its level should be below the level of the glass.
• Polyethylene or cellophane film is stretched over the top of the pelvis.
• A small weight is placed on the film, directly above the glass.
• The structure moves closer to the heat source.
• Soon drops of evaporated condensate will accumulate on the film and flow down.

All that remains is to remove the cellophane from the basin - the glass will contain drinkable water.

Note! These methods work great in natural conditions.

The third option for obtaining drinking water is partial freezing in the freezer.

• Pour sea water into a wide container.
• Place in the freezer.
• Monitor the freezing process periodically.
• As soon as a thin layer of ice appears, carefully collect it, this will be fresh water.
• Remove only a small layer of ice each time - its crystals contain almost no salt.

Note! Completely frozen seawater will produce salty ice.

Desalination of water in extreme conditions

Get some money drinking water Having abundant sea water, in extreme conditions, when there are kilometers to a natural fresh source, it is a matter of survival.

The fastest option is to build a primitive distiller on a fire.

• To do this, place a filled sea ​​water The container is covered with a lid on top.
• It is advisable to make a hole in the lid and insert a steam outlet tube there.
• If there is no hole and there is nothing to pierce it with, then the tube is simply clamped by the lid.
• The other end of the tube, through which drops of condensate will flow, must be lowered into a clean container.
• To speed up the release of steam, the tube is covered with a wet cloth or constantly watered with cold sea water.
• In the absence of a lid, a metal “roof” is constructed at an angle from the vessel; a clean vessel is placed at the lowest edge, into which the distillate will drain.

If this happens in the summer heat, there is a very simple option to desalinate water, but in terms of time it will not be as fast as using fire. To do this, you only need one container, film and a dug hole.

• You need to dig a hole a little deeper than the height of your container.
• The bottom of the pit is abundantly watered with sea water.
• An empty container is placed in the center of the recess.
• The pit is completely covered with film, and its edges are tightly fixed with sand, pebbles, and earth.
• A weight is placed on the center of the film, directly above the vessel - a pebble, stick, lump of soil or a handful of sand so that the coating becomes concave.
• The water, evaporating, will begin to settle on the film roof and flow down an inclined path straight into the placed container.
• In the heat, in a couple of hours the vessel will collect enough water to drink.

Note! The condensate is absolutely devoid of salts, so to quickly quench your thirst, experienced extreme sports enthusiasts advise adding a little sea water.

Another method of desalination is freezing, suitable for harsh winter conditions. Its algorithm is similar to home freezing, only the street frost will act as a freezer here. You need to scoop up sea water and wait for ice crystals to appear on the surface - they will taste fresh, and you can easily drink such water.

The main problem of any shipwrecked person is the lack of drinking water. Seriously, paradise islands, with abundant fruits and clean springs, are rather the exception to the rule. Most often you have to survive in areas that are much less suitable for life. And if you can put it off until later, then there’s a problem water extraction stands up immediately and very sharply.

In fact, there are plenty of options. You can collect, you can try to dig a “well” on the sandy shore, in which the water, when passed through meters of sand, will turn out to be completely drinkable. Or you can call on your school knowledge of physics to your aid and build the simplest seawater desalinator.

So. For water desalination you will need:

• plastic bottle
• large light container
• small dark container
• polyethylene film

Then everything is simple. We bury a large container in the ground to the brim, and place a medium dark container filled with sea water in it. And we place a glass or a cut plastic bottle in it, and we try in every possible way to prevent salt water from getting in there. We leave this entire structure in the sun, hermetically covering it with film. It is also recommended to place a small weight directly on the film above the glass - this will allow the water to flow there. And, in fact, that’s all. After 8 hours, you will have just a glass of 200 milliliters, on average.

The principle of operation is simple: under the influence of sunlight, the dark material heats up, and the evaporation of water increases. The polyethylene film does not release water vapor to the outside, and the walls of the large container provide the temperature difference necessary for condensation.

Actually, the recipe may change. Some, for example, advise not to use a large container, but simply dig a hole in the sand and place the dark vessel there. Others prefer to use opaque polyethylene. In short, there are options.

In any case, for effective water desalination One such design will really not be enough. But five or six pieces will already be enough to provide you with your daily norm, and will also free up time for more useful things. The main problem is that the shipwrecked person often has no property at all, so there is no talk of pots at all. In this case, the recipe is transformed and simplified.

Thanks to the pollution of the world's oceans, plastic bottles and old bags can be found on the coast of almost any island. Dirty, wrinkled, with holes in places, but it's better than nothing. Therefore, we dig a hole, throw branches and leaves moistened with sea water to the bottom, and place a cut plastic bottle in the center. On top there is polyethylene in several layers. Water will have to be added periodically.

Theoretically, polyethylene can be replaced with wide leaves, but this replacement further reduces the efficiency of the process water desalination. In short, you can’t count on high performance here. But this is better than nothing.

Issues discussed in the material:

• Why is there a need for desalination of seawater?
• What methods exist for desalinating seawater?
• 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 is obtained that is suitable for domestic use and consumption. Our article will talk about methods and technologies for desalination of sea water.

60% of the earth's surface consists of areas where there are either no sources of fresh water at all, or there are but a very small amount. Since many arid areas have few freshwater bodies, watering problems arise. 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 its 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. They will also be negatively affected by the presence of alkalis in the water. Many countries, including Russia, are looking for ways to desalinate salty water sources, which would help cope with drought problems in areas located near the sea.

In countries with well-developed industry, there is an increasingly acute shortage of fresh water supplies. In particular, this applies to the USA and Japan, where the volumes of water required for industry, agriculture and domestic needs have long exceeded those available.

The amount of fresh water does not meet the needs and developed countries With low level precipitation, such as Israel and Kuwait.

Russia ranks first 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 the rivers into its basin globe, then it will take almost 300 days to fill.

However, most of Russia’s water resources are concentrated in practically uninhabited and undeveloped areas of Siberia, the North and Far East. To the 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 south-eastern part of the Russian Federation, have enormous mineral resources, but do not have freshwater sources.

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

In the process of desalination of seawater, an important parameter is its salinity, which is understood as 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 lightly salted. The average salinity of the World Ocean is 35g/kg.

In addition to 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 varying concentrations were discovered in the marine subsoil, including lithium (Li), rubidium (Rb), phosphorus (P), iodine (J), iron (Fe), zinc (Zn) and molybdenum (Mo).

Marine water reserves 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 that contains no more than 0.001 g/ml of salts can be suitable for food. In order to achieve such a concentration, use various technologies desalination of sea water. Experts are trying to develop desalination systems that would consume little energy, but at the same time purify the water as much as possible for use by the population.

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

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

A seawater desalinator is a device that can remove dissolved salts from water. After the purification procedure, water is obtained that can be used not only for household needs, but also for drinking. The design of the device is convenient and practical in operation.

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

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

To obtain all these types, different ship-based desalination plants are used.

Desalination technologies include the following:

1. Distillation, in which a desalination plant heats and evaporates seawater. The resulting steam is “caught” and brought to the required temperature.
2. Filtration, in which the device operates on the principle of reverse osmosis. Salt water is purified without changing from one state to another. The operation of such a device is based on bringing the concentration of dissolved impurities to the optimum. Very high pressure allows you to “squeeze out” excess salt particles.

The largest desalination plant on the planet is located in the Israeli city of Hadera. This unit is comparable in size to an entire plant. It desalinates about thirty-three billion gallons of seawater each year. The desalination plant operates on the principle of reverse osmosis, as a result of which Mediterranean waters are not subjected to heat treatment.

The installation is completely sealed, creating a greenhouse effect without allowing vapors to escape outside. As a result, the pure aqueous residue is retained in a larger volume. At the end, the plug is unscrewed and the purified liquid is poured into a container.

Similar devices are used in navy. They use the heat of the liquid, which serves to cool the main and auxiliary diesel engines. Purified water, heated to 60 °C, enters the inlet through the pipes of the heating battery. Upon exiting, the temperature of the liquid drops to approximately 10 °C.

Vacuum desalination plant produces about 800 liters of distilled water per hour. It can satisfy all fresh water needs without wasting fuel energy, and full automation saves on maintenance costs. Since the evaporation temperature is quite low, the water desalination plant can operate for six to twelve months without requiring cleaning.

It is known that the Israeli population 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 needs of the entire country.

Today, a variety of equipment is used to desalinate seawater, including unique solar-powered desalination plants. They are filled with water, which, under the influence of solar heat, turns into steam, condenses on the walls of the housing and then settles at the bottom of the device.

Today, two desalination methods 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-permeable membranes under pressure significantly higher than the difference in pressure between fresh and sea water (for the latter it is 25-50 atm.).

The microscopic pores of the filters freely allow only small water molecules to pass through, trapping 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 osmism 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 mode.

But still, this method also has its disadvantages. 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). This method also requires increased operating costs, since it requires regular purchase of related chemicals and replacement of membrane filters.

Wonthaggi Desalination Plant is the world's largest membrane water 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 using reverse osmosis. It processes 330 thousand cubic meters of water per day.

The essence of the thermal method (distillation) is that at a seawater desalination station, the liquid is boiled, and the resulting steam is accumulated and condensed. This creates a distillate - fresh water. You can evaporate 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 create steam. At the same time, it is cooled to the saturation temperature of the remaining brine. The disadvantages of this method are cost, high energy intensity, and the presence of an external source of steam. However, it is this that provides 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:

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

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 load on the general water supply.

Water purification at this installation will take place in several stages. It is planned to use a combined membrane technology for clarification, a reverse osmosis method for purification from salts, and an ion exchange method for polishing softening.

The system will operate automatically; only one operator will be needed to control the process.

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

Scientists have high hopes for using nuclear energy to purify water resources, which would make desalination technologies much cheaper.

Do-it-yourself desalination of sea water at home and in extreme conditions

If you need to purify seawater from salts while camping, the best option for this is a homemade distiller, similar in design to well-known distillation apparatuses.

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

Salts are released from the mixture because the boiling point of the brine solution is slightly higher than that of pure water. Therefore, the fresh component evaporates faster and settles in the collection container.

To desalinate sea water in camping conditions you will need:

• first of all, the water itself, which is always in abundance on the shore of the sea or salt lake;
• a pot or kettle as a heating container;
• an aluminum tube, which should be prepared before the start of the hike;
• 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, and insert a tube into the neck of it.

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

Then the structure should be covered with sand so 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 pot or open kettle of sea water. In this case, the fire is lit a short distance from the bottle with the pipe.

After the fire flares up, the water in the container will heat up and begin to bubble, and the steam will gradually spread through the tube into a bottle buried in the sand, where it will settle as condensation. Gradually, up to 200-300 grams of clean fresh liquid forms at the bottom of the container.

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 water. Therefore, long-known home desalination methods are very popular among people.

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

There are two more ways to purify water from salt, which 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 filtration using activated carbon. 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 large costs for the production and operation of membranes, as well as significant energy capacity. In addition, after desalination using this method, 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 complex, and the cost of desalination of seawater only increases every year.

In addition, only 1/3 of the world's freshwater reserves are found in soil (2/3 are frozen in snow covers and glaciers). And they are used by humans so quickly that nature does not have time to replenish what is lost.

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

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

For example, an American spends on average about 400 liters per day, while a resident of an underdeveloped country uses only 19 liters. Half of the world's population has no running water at all. All this will one day lead to people paying special attention to the oceans as sources of water.

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

Based on the results of design developments, 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. Assessing underground reserves of varying degrees of salinity in arid areas, we can conclude that desalination is the only economically viable method of water supply for them, given their remoteness from natural freshwater sources.

Desalination methods used today can be productively used to return used water resources to nature without degrading 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 this directly determines how well the drinking liquid will be purified.

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

The Iceberg company offers favorable conditions for servicing its clients:

• free delivery of water to your home or office: buyers pay only the cost of the product;
• the wells from which our water is drawn have registration documents in the State Water Cadastre of the Russian Federation;
• Advanced technologies are used to extract and bottle water, which helps preserve and enhance 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 the devices to be installed even in small spaces;
• delivery of drinking water to your home or office is carried out at a minimal 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 with high-quality drinking water, so we have prepared the most favorable conditions for our clients.

Obtaining drinking water on a desert island is not easy, but quite doable.

If you find yourself on desert island, then with some intelligence and a container made from leaves or sunken fruits, you have a good chance get fresh water and stay alive for many days. To turn salt water into drinking or fresh water, you need to rely on the principles of nature. As seawater evaporates, clean water is collected, leaving salt behind. The following process is based on the solar desalination method to collect water for drinking in an emergency.

Instructions on how to get drinking water

1. Dig a hole to collect water. The hole should be at least 1 meter deep and wide enough for you to reach the bottom with your hand. Once you get close to 1 meter, you should see very wet sand or a puddle of water. Take your time, as you are limited in water, and exertion will make you thirsty ahead of time.

2.Place the container in the center of the hole. The container can be a hollowed out coconut, fruit or large leaves. If there is enough vegetation on the island, you can add it to the hole around the container. Water from the vegetation will evaporate and accumulate in the container.

3. Cover the hole and bend the cover. Place a large leaf (such as from a palm tree) over the hole and cover it as completely as possible. Secure the outer edges of the sheet with stones. Place a few pebbles in the center of the lid to create a small indentation above the container. This will direct the water into the vessel. During the day and night, dew and condensation will collect on the homemade covering and flow into the vessel.

4.Periodically remove the container from the pit to drink water or fill other containers for later use. Place the vessel back into the hole to continue accumulating water. The water will be safe to drink. No

Water- the source of life for all living things, but you need to distinguish which water is healthy and which is not. Approximately 99% of all water on earth is the water of oceans and seas, that is, salt water, unsuitable for consumption. Many people in the world need living, fresh water, and today we will tell you how to get fresh water from salt water.

How to make fresh water from sea water at home?

Fresh water differs from salt water in the amount of salt and other chemical elements. The most popular method is to separate salts from water by distillation.
This method involves heating water to boiling point and collecting the vapors in the form of condensate. This method is well described in the article - .

There is also another method, the so-called desalination. It consists in passing salt water through a membrane, which is capable of passing only clean water without salt components. But this type of purification is not very effective, since the membrane allows a very small amount of water to pass through over a long period of time.