Membrane desalination plant. Desalination of well water

Desalination of sea water has become possible thanks to the reverse osmosis method. Desalting systems effectively remove salts, soften water, making it drinkable and industrial. Our company offers seawater desalination plants "AQUALINE OS", which we design and manufacture at own production... The cost of the equipment is quite reasonable, which makes it affordable for both small businesses and large companies.

The principle of operation of reverse osmosis seawater purification plants "AQUALINE OS"

Semi-permeable membranes are part of any desalination system. These high-tech devices are entrusted with the function of a molecular sieve, with which they do an excellent job, freeing water from salts, minerals, organics, as well as harmful bacteria and viruses. The process itself is as follows. On membranes under high pressure water is supplied. The membranes are designed to allow only water molecules to pass through. Large molecules of various substances and compounds are retained, forming a saline solution, which is discharged into the sewer. Pure water is obtained at the exit.

Advantages of our AQUALINE OS industrial desalination plants

• High performance
  Each system is equipped with a high pressure pump, which greatly increases the operational efficiency and productivity.
• Membrane cleanability
  Over time, the membrane becomes clogged, but this does not require replacement. It is enough to carry out the operation to restore the permeability to return the equipment to its original operating characteristics.

Why more and more customers are purchasing water demineralization systems "AQUALINE OS" in LLC "Pervaya Vodnaya Kompaniya"

• Affordable cost
  The unit price includes only material and manufacturing costs. All stages of manufacturing are carried out directly in our production. In addition, we are suppliers and do not cooperate with intermediaries. These factors are responsible for the low cost.
• Additional services
  Our staff includes only experienced and highly qualified employees in the person of engineers, designers, technologists and production specialists. This allows us to develop serious projects, successfully implement them, provide customers with launch and maintenance services.

How to buy an industrial seawater purification system "AQUALINE OS"

There are 2 ways to place an order remotely. You can fill out and send an application through the website or call the phone number in Moscow 8 800 250-96-87. Our operators will tell you in detail about all stages of the acquisition and advise on additional services.

Water desalination, a method of water treatment in order to reduce the concentration of dissolved salts to a degree (usually up to 1 G/l), at which the water becomes suitable for drinking and household purposes. Deficit fresh water is felt on the territory of more than 40 countries, located mainly in arid and arid regions and making up about 60% of the entire surface of the earth's land (according to calculations, by the beginning of the 21st century it will reach 120-150 10 9 m 3 per year). This deficit can be covered by desalination of saline (salinity more than 10 G/l) and brackish (2-10 G/l) oceanic, sea and underground waters, the reserves of which account for 98% of all water in the globe(see also Water resources ). The lack of fresh water can be eliminated by supplying it through pipelines or canals from areas in which it is available in excess. For example, in the USSR, the Seversky Donets - Donbass canals were built (about 130 km), Irtysh - Karaganda (about 460 km), 3 stages of the largest in the world Karakum Canal , there are (in the Kazakh SSR) water pipelines Ishimsky and Bulavinsky, with a length of more than 1700 km each. However, with a significant removal of freshwater sources, on-site desalination of salt water is cheaper than fresh water supplied through aqueducts. With water consumption up to 1000 m 3 /days on-site desalination of salt water is more profitable than supplying fresh water over a distance of more than 40-50 km, with water consumption 100 000 m 3 /days- more profitable than supplying fresh water over a distance of more than 150-200 km.

Throughout the world in 1974, St. 800 large stationary desalination plants (OS) with a total capacity of about 1.3 mln. m 3 /days fresh water. The largest of them have a capacity of 160 thous. m 3 /days(in Shevchenko, USSR; heat comes from a nuclear power plant with a fast neutron reactor) and 220 thous. m 3 /days(in Kuwait City, Kuwait; the OS boiler house runs on associated gas from oil production). Most marine vessels have their own DUs (distillation type only).

O. in. can be carried out both with a change in the aggregate state of water ( distillation , freezing), and without changing its state of aggregation (electrodialysis, hyperfiltration, or reverse osmosis, ion exchange, water extraction with organic solvents, water extraction in the form of crystallization water of crystalline hydrates, water heating to a certain temperature, ion sorption on porous electrodes, biological method- using the ability of some algae to absorb salts in the light and give them away in the dark, etc.). In accordance with O.'s methods of century. exists Various types OU. Distillation OUs (single-body and multi-body, by the desalination method - vapor compression and solar) are used for desalination of sea water and salt water. O. in. electrodialysis and hyperfiltration (reverse osmosis) economically at a salt content of 2.5-10 G/l, ion exchange - less than 2.5 G/l... Of the total volume of desalinated water obtained in the world, 96% is accounted for by distillation OC, 2.9% - by electrodialysis, 1% - by hyperfiltration, and 0.1% - by freezing and ion-exchange OC. Depending on the capacity, the OU consists of one or several desalination plants connected in parallel.

Distillation desalination plants are single-stage ( rice. 1 ), multistage with tubular heating elements, or evaporators ( rice. 2 ), multistage with instant boiling ( rice. 3 ) and vapor compression. A multistage evaporator consists of a series of evaporating chambers in series with tubular heating elements. The heated salt water moves inside the tubes heating element, heating steam condenses on their outer surface. The heating and evaporation of water in the first stage is carried out by the steam of a distillate-fired boiler; The heating steam of the next stage is the secondary steam of the previous evaporation chamber. In desalinators with instant boiling, salt water passes sequentially, from the last to the first, through condensers built into the evaporation chambers, being heated by the heat of condensation, it enters the head heater, heats up above the boiling point of water in the first evaporation chamber, where it boils. Then the steam condenses on the surface of the condenser tubes, and the condensate flows into the sump and is pumped out to the consumer by the pump. Non-evaporated water flows through the water seal into the next chamber with a lower pressure, where it boils again, etc. Heat consumption for production 1 kg fresh water in a single-stage distillation watermaker is about 2400 kJ; recuperation of phase transition heat in a multistage desalination tank reduces heat consumption by 1 kg fresh water up to 250-300 kJ.

Electrodialysis watermaker ( rice. 4 ) is a multi-chamber filter-press type apparatus consisting of chambers bounded on one side by a cation-exchange membrane, on the other - by an anion-exchange membrane. The chambers are located between the cathode and the anode, to which a direct electric current is supplied. Desalinated water enters the desalination chambers. Under the influence electric field cations of salts dissolved in water move towards the cathode, anions - towards the anode. Since cation-exchange membranes are permeable in an electric field for cations, but impermeable for anions, and anion-exchange membranes are permeable for anions, but impermeable for cations, salt water in desalination chambers is desalinated, while the salts removed from it are concentrated in brine chambers, from where they removed together with the rinse salt water. Electricity consumption for O. in. electrodialysis depends on the salinity of desalinated water (2 tue· h by 1 l for desalination of water with a salinity of 2.5-3 G/l and 4-5 tue· h by 1 l for desalination of water with a salt content of 5-6 G/l).

Hyperfiltration desalination plants consist of a high pressure pump (5-10 Mn/m 2, or 50-100 bar), pumping salt water through flat or tubular membranes or hollow fiber made of cellulose acetate or polyamide resins, capable of passing water molecules under a pressure higher than osmotic, but not allowing hydrated ions of salts dissolved in water to pass through.

In the deserted southern regions and on the waterless islands, solar desalination plants are used; they give about 4 in the summer months l water per day from 1 m 2 surfaces that receive solar radiation.

Lit .: Apeltsin I.E., Klyachko V.A., Desalination of water, M., 1968; Pavlov Yu.V., Desalination of water, M., 1972: Slesarenko V.N., Modern methods desalination of sea and salt waters, M., 1973, Spiegler K. S. [e. d.], Principles of desalination, N. Y.-L., 1966.

DESALINATION OF WATER- a method of processing highly mineralized water in order to reduce or completely remove salts dissolved in it.

The lack of fresh water is already felt in many countries of the world. In the USSR, the lack of fresh water is felt in the territory of Turkmenistan, Kazakhstan, Uzbekistan, Azerbaijan, in a number of districts North Caucasus, Ukraine, Western and Southern Siberia, the Urals, the Volga region, where it can be largely covered by desalination of the significant resources of highly mineralized ground or sea waters available in these regions.

O. in. carried out either by separating the actual water molecules, or by removing salt ions from the solution. Based on these features, desalination methods are divided into two groups: with a change and without a change in the aggregate (phase) state of water. The first group includes thermal desalination (distillation) and processes using cold (freezing), the second - chemical, membrane, extraction and adsorption, as well as biol, methods.

The most widespread methods of O. century. are distillation, freezing, electrodialysis, reverse osmosis and ion exchange.

The distillation method (see) is based on the fact that when water is heated, its molecules, due to thermal and vibrational motion, acquire energy sufficient to overcome the forces of intermolecular attraction, and the resulting vapor during subsequent condensation gives desalinated water. By the nature of boiling and design features there are boiling, adiabatic (low-temperature boiling in vacuum), thin-film, hygroscopic, hydrophobic and thermal diffusion desalination plants. The use of distillation is most economical in the desalination of salt (sea) waters to obtain a significant amount of fresh water.

Desalination by freezing (natural and artificial) is based on the use of the difference in freezing temperatures of fresh (0 °) and brackish waters with salinity up to 10 g / l (-1.6 °). The natural freezing method is used in areas with cold climates. Artificial freezing involves cooling water by introducing a hydrophobic refrigerant (butanes, freons) directly into desalinated water, evaporating cooled water in a vacuum, using water with a lower temperature as a refrigerant. Theoretical calculations show that the freezing method can be one of the most cost-effective. However, the technology, difficulties, high metal consumption of desalination plants and high consumption of desalinated water in the technological process of such desalination delay the industrial implementation of this method.

The method of electrodialysis (electrochemical) is based on the transfer of ions of salts dissolved in water in an electric field between electrodes immersed in desalinated water; in this case, the cations move to the cathode, and the anions to the anode. To prevent a reverse reaction, cation-and anion-selective membranes are installed near the electrodes, which do not allow oppositely charged ions to pass through. The electrodialysis method is most appropriate for the desalination of brackish waters (with salinity up to 10 g / l).

The reverse osmosis method is based on creating a pressure in a system with porous synthetic membranes that exceeds the osmotic pressure; in this case, water molecules are filtered through membranes and salts are retained.

The ion exchange method is based on sequential filtration of water through filters loaded with cation and anion exchange resins - ion exchangers (see). The desalination process takes place in two successive stages: removal of cations and anions. The method is most promising for desalination of low-mineralized waters (with salinity up to 2.5 g / l).

Depending on the desalination method, specific gigabytes are installed. conditions of use and operating modes of desalination plants, including methods of preliminary preparation of source water, its additional purification, correction of salt composition, disinfection and conditioning of desalinated water, as well as conditions for the use of structural and technology, materials and reagents.

Water received different methods desalination, must comply with the current state standard for drinking water (see. Water, sanitary and hygienic requirements), and also be physiologically complete. The use of pure distillate for drinking purposes has an unfavorable effect on the state of went. - kish. tract and water-salt metabolism of a person. According to " Methodical instructions on hygienic control over the design, construction and operation of group agricultural water supply systems "No. 2058-79, approved by the M3 USSR, the minimum required level of salinity (100 mg / l) and optimal levels of salinity of desalinated drinking water chloride-sulphate (200-400 mg / l) and hydrocarbonate (250-500 mg / l) classes. It also regulates the minimum level of calcium (1.5 mg-eq / l), the maximum (6.5 mg-eq / l) and minimum (0.5 mg-eq / l) permissible levels of alkalinity, the minimum required level of hardness (1, 5 mg - eq / l), the maximum permissible concentration of boron (0.5 mg / l) and bromine (0.2 mg / l).

Bibliography: Apeltsin I. E. and Klyachko V. A. Desalination of water, M., 1968; Rakhmanin Yu. A. et al. Experimental and clinical and physiological materials to substantiate the lower limits of salinity of desalinated drinking water, Gig. and dignity., No. 7, p. 16, 1975; Sidorenko GI and Rakhmanin Yu. A. Desalination as a hygienic problem in the USSR, ibid., No. 12, p. 14, 1977.

G.I.Sidorenko.

Freeze water desalination - new method, the development of which began in the second half of the 70s. Detailed studies are currently underway different processes, as a result of which three types of freezing processes have been identified: when salt water comes into contact with a heat transfer surface cooled by refrigeration unit; when evaporating chilled water in a vacuum; and by direct contact of water with a water-immiscible refrigerant. The main stages in desalination plants of all three types are crystallization-ice formation; separation of ice and brine and washing ice from brine; and melting ice. In installations of the third type, a refrigerant separation process and fresh water are added. [...]

Desalination of water by reverse osmosis (hyperfiltration) occurs without phase transformations. In this case, energy is mainly spent on creating the pressure of the source water - a medium that is practically incompressible. The osmotic pressure of solutions similar in composition to natural waters, even with low mineralization, is quite high, for example, for seawater containing up to 3.5% salts, it is about 25 at. It is recommended to maintain the working pressure in desalination plants at least 50-100 atm and even higher, since their productivity is determined by the difference between the working and osmotic pressures. [...]

Desalination of water consists in the complete or partial removal of dissolved salts from sea or any other salt water. Desalination is currently used in the production of demineralized water for industrial chemical processes and, in limited quantities, for human consumption in waterless areas (for example, in areas adjacent to the Arabian Sea and on some islands in the Caribbean). With the increase in the US population, the demand for fresh water has also increased to such an extent that it cannot be met by natural freshwater supplies alone. Thus, desalination is becoming a very important way to obtain fresh water. [...]

When desalinating water in the open seas, the problem of removing brines is easier to solve. In the event of their dispersed discharge into the sea, there is no need to fear any significant negative consequences. Discharge of brines is also possible during the construction of desalination plants on the shores of the inland seas (Caspian or Azov). [...]

We come across the ideas of water desalination in the Natural History of Pliny the Elder (23 or 24-79), an ancient historian who lived in the 1st century BC. n. NS. He describes two methods of desalination. The first, the oldest, is that the rune ( sheep skins), hung over the side of the ship at night, absorb moisture, and in the morning it can be squeezed out, thus obtaining fresh water. The second method is described by him as a legend with a long history. Its essence is to obtain fresh water inside a wax ball, lowered into the sea. However, neither the author of Natural History, nor other researchers who turned to the history of desalination were able to find experimental confirmation of this "method". [...]

Usually amines (diisopropylamine, triethylamine, mixtures of the latter with diethyl-methylamine), alcohols (butyl, etc.), ethers, etc. are used as extractants for water desalination. Triethylamine is one of the best solvents in terms of extraction properties and economy. The diagram of the mutual solubility of triethylamine and water of various salinity is shown in Fig. 273. [...]

Salts dissolved in water are removed by distillation, electrodialysis, ion exchange and reverse osmosis. Distillation is the process of converting treatment water into water vapor, which is then condensed. Distillation is one of the methods used to desalinate seawater. Electrodialysis consists of separating positive and negative ions with the help of selective membranes, which pass through a constant electric current ions from the treated solution on one side of the membrane to the concentrated solution on the other side of the membrane. The problems arising in the electrodialysis method of water desalination are associated with chemical precipitation of poorly soluble salts and clogging of the membrane with colloidal masses. To prevent clogging of membranes, desalinated water from surface sources must be pretreated (chemical precipitation and purification using activated carbon to extract molecules organic matter and colloids). Desalting, carried out by ion exchange, is described in clause 7.9. Due to the high cost of these processes, apparently, none of them will find wide application in the practice of water purification. [...]

Salt composition of water. The salt composition of water is understood as the totality of mineral and organic compounds... Depending on the amount of dissolved salts, fresh water is distinguished (up to 0.5% o) (% o - ppm - salt content in g / l of water), brackish (0.5-16.0% o), sea (16-47 % o) and salted (more than 47% o). Sea water contains mainly chlorides, while fresh water contains carbonates and sulfates. Therefore, fresh water is hard and soft. Too freshened, as well as oversalted, reservoirs are unproductive. The salinity of the water is one of the main factors determining the habitat of fish. Some fish live only in fresh water (freshwater), others in sea (sea). Anadromous fish change seawater to fresh water and vice versa. Salinization or desalination of waters is usually accompanied by a change in the composition of the ichthyofauna, food base, and often leads to a change in the entire biocenosis of the reservoir. [...]

When choosing a method for desalination and desalination of water, one should take into account: the salinity of the source water, the specified capacity of the desalination plant, as well as the cost of heat sources, electricity and the required chemicals and materials. In practice, there is a need for desalination of water with a total salt content of 2000 to 35000 mg / l. [...]

The use of atomic energy is very promising for water desalination. Work in this direction is already underway. At present, a fast neutron reactor is being built in the USSR on the shores of the Caspian Sea, which will be combined with a distillation desalination plant. In the USA, it is planned to build this type of station with a capacity of 150-750 MW, with a desalination unit with a capacity of 225-675 thousand m3 / day. [...]

The process of removing salts from water, depending on the degree of their extraction, is called desalination or desalination. During desalination of water, the concentration of dissolved salts is brought to a limit close to their content in fresh waters, during desalination - to their content in distilled water. [...]

The high cost of the desalination process is the main disadvantage and an obstacle to its widespread adoption. Fresh water has traditionally been one of the cheapest products and has sold for a few cents per ton. The price of water obtained by any of the desalination methods is several times higher than the price of natural water in industrial areas of the United States. Research in the 50s and 60s led to a decrease in the cost of distilled water from $ 1.30 in 1950 to $ 0.23 / m3 in 1974 (for comparison: the cost of natural fresh water in US cities is 0.05 USD / m3). [...]

Water to be cleaned is supplied to the central chamber. When the current is switched on, ions penetrate through the diaphragms into the cathode and anode spaces. Their reverse diffusion is hampered by diaphragms. The apparatus for desalination of water consists of ten cells connected in series. Water Fig. 62. [...]

Desalination of water by the method of electroadsorption of ions by porous electrodes is of considerable interest. It is based on the fact that the formation of double electric layers on oppositely charged from a source direct current inert electrodes with a highly developed surface is accompanied by the extraction of very significant amounts of dissolved salt. [...]

Israel uses a vacuum freezing desalination plant. Pure ice crystals form in the saline solution simultaneously with the evaporation of some of the liquid. These ice crystals are then separated from the solution and washed. The washed crystals are brought into contact with compressed steam. As the vapor condenses, the ice melts. One of the advantages of this system is a very low energy consumption - 11-14 kWh per 1 m3 of produced water, and with the improvement of the project this figure can be easily reduced to 7-9 kWh per 1 m3. The Israeli plant consists of four units each with a capacity of 10 m3 / h. It treats water from the Red Sea with a salt concentration of 4.2%. Each block consists of two adjacent cylindrical vessels with a diameter of 4 m. One operates in rinsing mode, the other as a freezer and defroster. There is a steam compressor under the dome of the unit, which sucks water vapor from the freezer and compresses it, then it enters the defroster, and the ice goes down the chute. [...]

We have already talked about the history of water desalination, and it was easy to see that its development was primarily associated with the fleet. By the 60s of our century, many technical problems of obtaining large quantities of desalinated water on ships had already been solved. [...]

The most important requirements for extractants for water desalination are high selectivity (water dissolved in a solvent must contain significantly less salt than the undissolved part of water), high extraction capacity, sensitivity of mutual solubility in the water - extractant system to temperature, low solubility of the extractant in water, ease of its regeneration, a sufficiently large difference in the densities of water and extractant, stability of the extractant when interacting with aqueous solutions salts, etc. Of the known solvents, the best extraction properties are possessed by secondary and tertiary amines containing from four to six carbon atoms in a molecule. [...]

Reverse osmosis (hyperfiltration) is a more promising membrane technology for desalination of waters with increased salinity. This method desalination is based on the phenomenon of osmotic transfer, that is, on the filtration of water through a set of semi-permeable membranes that allow water molecules to pass through, but retain salt ions. The essence of the process can be represented as follows. If solutions of different concentrations are separated by a semipermeable membrane, then water molecules will move towards equalizing concentrations, i.e., from more fresh water to more saline. This transition will be observed until the concentration of solutions on both sides of the membrane becomes the same. However, this will increase the volume of the initially saltier water. The difference in water levels on both sides of the membrane, corresponding to the equilibrium concentration, characterizes the osmotic pressure. It is quite obvious that for the desalination of salt water, the process must be directed in the other direction. [...]

After all, we are dealing with a fairly energy-intensive production that requires the investment of significant material resources. At first glance, this is so. Nevertheless, already in many countries, substantial material costs are being spent, solving the problems of life support of the population and development of the economy with the help of desalination. These costs, as you can see from the examples we gave earlier, justify themselves. It is also important that the improvement of the technology of distillation desalination constantly takes into account the economic side of this process, reducing the cost of the water produced from year to year. Membrane technology is developing in a similar way. [...]

This book does not discuss in detail the methods of desalination of water that change its state of aggregation. ' Note that at present, with a high salinity of water, distillation desalination plants are the most widespread. Their main function is to evaporate water, followed by condensation of steam, which leads to the production of fresh water. [...]

But, no matter what Carodran may have argued, the attitude of sailors towards desalinated water has not changed. [...]

Such a filter, it would seem, made it possible to enrich desalinated water with calcium, chlorine ions, to some extent hydrocarbonate, carbonate and sulfate ions, which should have made mineralized water more saturated in terms of chemical composition... Enrichment with magnesium ion in this case was not provided, although in natural waters its content is quite high. [...]

Yub.Rozval K.S. Features of the action of desalinated waters on the human body varying degrees mineralization // J. Hygiene and sanitation. 1971. No. 8. [...]

For its needs, mankind mainly uses fresh water, which makes up 1% of the total volume of the hydrosphere. To solve this problem, it is necessary to involve the desalination of the water of the World Ocean, The groundwater and glacier water (desalination plants of JSC "Komsomolets" - food tin). Due to the high cost and high energy intensity of desalinated plants, the share of desalinated water in the total volume of water supply is insignificant (USA - 7%, in our country - 1%). [...]

The best hydrate-forming substances used for water desalination are propane С3Н8 and fluorochlorine derivatives of fatty hydrocarbons - freons. These substances are non-toxic and at the same time are used as refrigerants to maintain the temperature required for hydrate formation. So, freon-12 (difluorodichloromethane CF2C12), having a bp. -23.7 °, forms a gas hydrate with water with structure II. When using propane (bp -42, ГС), which forms a gas hydrate with structure II, water desalination is carried out at 2-5 ° С and pressures up to 500 kPa. The temperature and pressure ranges at which the formation of gas hydrates is possible depends on the salinity of the water. Since the formation of gas hydrates is accompanied by the release of heat, the system must be cooled during the crystallization process. To accelerate the formation of seed crystals, the gas-water mixture is supercooled. The resulting gas hydrates retain a layer of brine on the surface of the crystals, therefore, after separation, they must be washed with desalinated water. [...]

Thus, when approaching the choice of splryalgp composition for imparting desalinated water drinking qualities it was possible to proceed from the sum of the hygienic knowledge about the regulation chemical substances in drinking water, biological role individual micro- and macrocomponents of water, which determine both its organoleptic and physiological properties. [...]

The essence of the method is that when a direct current is passed through water, ion exchange membranes are placed in the path of directional movement of ions, which have a selective ability to pass ions with a certain sign of charge. As a result, in one part of the cells formed by membranes, water is desalinated, and in the other, salts are concentrated. [...]

Some modification of the described crystallization process is the desalination of water by obtaining crystalline propane hydrates. The first stage consists in binding part of the water in the salt solution to crystalline propane hydrates. Then the crystals are separated from the mother liquor, purified from brine and, finally, the crystals are melted to obtain fresh water. [...]

The degree of elaboration of various technological processes of cleaning Wastewater is not the same. Some of them are at the experimental stage, others are at the pilot testing stage. The most developed is the membrane reverse osmosis method of desalting and desalting water with bringing the salt content to the level of drinking water (500 mg / l). Thousands of reverse osmosis water desalination plants are currently in operation around the world. This example of a large-scale implementation of the membrane method for water purification testifies to the reality of further development to large-scale use of other similar methods. technological processes methods. Membrane wastewater treatment methods have also proven themselves in small installations (stationary and mobile), on ships and offshore platforms. [...]

The desalination plant consists of a block of electrodialyzers, pumps, desalinated water (diluate) tanks, brine (concentrate) tanks, an acid tank, a polarity reversal unit and a control panel. [...]

The schematic diagram of the installation, which is the same for all possible technological variants of water desalination by the method of ion electroadsorption, is shown in Fig. 347. To avoid water decomposition and side redox reactions on the electrodes, the adsorption process is carried out at a voltage of no more than 1.5 V. Desorption of absorbed ions (regeneration of electrodes) is carried out by switching the polarity of the electrodes. During the regeneration period, adsorbed ions pass into salt water, which is discharged into the drain. [...]

Separate stages of research and development work on the creation of means of desalination of waters of high salinity, carried out in our country, were discussed in the USSR State Committee for Science and Technology at the level of temporary scientific and technical commissions. Such commissions, which included highly qualified specialists from various departments, were convened in 1970 and 1978. Their function consisted mainly in the development of a unified technical policy in the field of water desalination and demineralization. This approach was based on an assessment of the world scientific and technical level of the existing desalination technology and its development trends in foreign countries... Key technical problems in the field of desalination of waters of increased mineralization in the USSR and outlined the main ways of their solution. At the same time, much attention was paid to membrane technology. [...]

Distillers have been ordered, which will be produced on the island. Aruba another 10 thousand tons and on the island. Curacao - 4 thousand tons of fresh water per day. On both islands, fresh water is a byproduct of power plants because the heat from the waste steam is used to desalinate the water. The combination of a power station and a desalination plant is the result of Weira's many years of work. Installation on about. Curacao, at the time of this book's publication, had been operating at full capacity of 26,000 hours (three years) and was free of scale. [...]

Currently, the most studied agent is propane, on the use of which the scheme of water desalination by the hydration method is based, shown in Fig. 280. [...]

Installations of the first type are small containers with a light-absorbing bottom, filled with salt water. Above them, an inclined ceiling made of glass or transparent plastic is installed (Fig. 327 and 328). Water vapor, being cooled by colder atmospheric air, condenses on the inner surface of the unit; drops of desalinated water flow down into the peripheral trays. Depending on the design and materials used, the productivity of this type of desalination plant in the Central Asian republics reaches 10 liters of water per day from 1 m2. [...]

The main zone of water discharge is confined to the South Stavropol uplift zone (Ubezhenskoye field), where there are favorable conditions for the flow of water into the overlying sediments. Waters of variegated composition with mineralization less than 10 g / l are widespread here. Within the Tersko-Caspian trough, the Nogai step and partly the Chernollesskaya depression, an abnormally high pressure zone is distinguished, which is characterized by a predominance of waters with a salinity of 35-60 g / l. In the lower part of the Upper Cretaceous complex, waters of increased mineralization are often found (60-90 g / l, rNa / rCl 0.8-0.97). Such a change in water salinity along the section of the complex is associated with the influx of desalinated water from the overlying clayey sediments of the Paleogene during their compaction. [...]

At present, high-capacity electrodialysis plants for desalting fresh water have been developed and are in operation. Thus, the work reports on the results of setting up an electro-palysis installation with a capacity of 250 m3 / h for desalination of water with a salinity of 500-2000 mg / l. The installation consists of two modules with 300 pairs of cells, size 1500X1500 mm. The equipment of the installation is made of plastics. The water is pre-decarbonized on a weakly acidic cation exchanger and softened on a strongly acidic cation exchanger. A weakly acidic cation exchanger is regenerated by HC1, and a strongly acidic one is also HC1, but with the addition of a part of the brine from the electrodialyzer. The energy consumption was 1.77 kWh / m3. The decrease in salt content was on average 40% of the initial one. [...]

Electrodialysis desalination plants are divided into direct-flow and circulation ones. In one- and multistage direct-flow installations, the specified desalination of water occurs in the process of its flow through the cells of the bath. In circulating water, desalinated water is passed through the cells of the bath until the salt content in it drops to a predetermined value; they are batch and continuous. The choice of installation is carried out on the basis of technical and economic calculations. [...]

This question is not new. It arose almost simultaneously with the emergence of distillation apparatus intended for sea-going ships. And the sailors themselves were the first to ask it. Desalinated water was tasteless. She did not quench his thirst, caused unpleasant sensations. The sailors refused to drink it. In the XVIII century. distillation cubes the ships were installed by the French Maritime Ministry. And it was this department that was the first to respond to the complaints of the sailors. The prisoners were selected for the experiment. Six people were imprisoned for 30 days on the Aisne island in the middle of the roadstead of the port of Rochefort. The only water to drink was distillate. None of the prisoners died, outwardly they were all healthy. And on December 29, 1817, the Inspector General of the French Navy, Caraudran, published an article in the Monitor completely rehabilitating desalinated water. [...]

Industrial electrodialysis plants consist of a large number parallel cameras. In multi-chamber installations, brine chambers and water desalination chambers (working diluate chambers) are formed by alternating cationic and anionic membranes. The first ones are allowed to electric field cations, but retain anions, the latter, on the contrary, allow anions to pass, but retain cations. [...]

The unit for hydrate separation is in many ways similar to the URUS unit (see X1X-21). The hydration reactor replaces the URUS system freezer. Salt water and hydration fluid are injected into this chamber at a specific pressure and temperature. Part of the hydrating agent turns into steam and upon absorption of heat causes the formation of hydrate crystals. The crystals are then washed from the brine and sent to the smelting chamber, where the heat required for melting is obtained by condensing the compressed vapor from the reactor. The main problem, as in the NRUS system, is the problem of separating desalinated water and a part of the hydrating agent. In this system, the melting chamber is located outside the reaction vessel, in contrast to the URUS system, where it is placed in a combined cell (hydroconverter). [...]

The excess amount of propane leaving the main compressor is additionally compressed in the secondary compressor, then condensed in the heat exchanger when cooled with desalinated water and subcooled by the effluent brine and the original seawater. Subcooled propane, getting into the reactor, instantly evaporates, compensating for the heat losses of the reactor system. The resulting fresh water and brine are passed through turbines designed to recover part of the energy used to drive the pumps for seawater supply. [...]

Siberian vendace in Yakutia is the main commercial species in all rivers flowing into the seas of the Arctic Ocean. The vendace spends a significant part of its life in the desalinated waters of the coastal zone and near-delta areas, i.e. on the shelf. The basis of the fishery is sexually mature individuals with a body length (ac) of 270-350 mm, more often 300-330 mm, weighing 100-250 g. For the period 1991-1999. the annual catch of vendace in the water bodies of Yakutia averaged 750 tons. [...]

Oztegiv and Meeorie, apart from their residential freshwater forms, are typical inhabitants of brackish waters that do not extend far from the coast into the sea. Capelin is already a typical pelagic fish that spends much of its life in the sea, where it is often seen by whalers when it jumps out of the water in pursuit of whales. [...]

This method is based on high pressure filtration of solutions through suitably prepared cellulose acetate membranes on porous tubes. In this case, the filtrate has a significantly lower concentration of solutes than in the original solution. The method of water desalination by hyperfiltration is based on the filtration of salt water through semi-permeable membranes that allow water to pass through, but retain hydrated ions of salts dissolved in water. [...]

In 1907, on the Arabian coast of the Red Sea, in Jeddah, which at that time was part of the Ottoman Empire, two operatives were installed. They worked on solid fuel. In 1928 they were replaced by more advanced immersion tube evaporators with a fresh water capacity of 135 m3 / day each. For this city, the use of desalinated water to this day is essential element life support. The memory of its first desalination plants is kept by original sculptures assembled from their parts. [...]

During low tide, the soil dries up significantly and the salt content in it increases several times. Mangrove trees have an amazing ability to tolerate large fluctuations in the concentration of salts (mainly table salt) in the soil. Their roots ensure the absorption of desalinated water by ultrafiltration, as shown by the studies of P.F. Nevertheless, salt accumulates in tissues, especially strongly in old leaves due to prolonged transpiration. [...]

However, none of these methods for removing residual brines can be considered as universal, suitable for any area. Moreover, the removal of waste from desalination plants, even with their low productivity in some places, becomes a difficult task, the solution of which sometimes depends on the very possibility of desalination of waters of high salinity. [...]

It should be noted that in freezing and gas hydrate installations with direct contact devices, highest odds heat and mass transfer with a low thermal head, which can significantly reduce energy costs and, consequently, investment in equipment. When using these processes of water desalination, there is no intense corrosion of materials and scale formation. Since the gas hydrate plants did not pass the operational check, the economic evaluations of the method presented in the literature can be taken as indicative. According to available data, the energy costs for desalination using Freon-31 will amount to 4.5 kWh per 1 m3 of fresh water. [...]

Propane and various types of freons are promising hydrate-forming gases. At a relatively low overpressure and temperatures above 0 ° C, conditions are created for the precipitation of gas hydrates in the form of a light snow-like mass. The subsequent washing of the crystals from the brine, the release of gas and its return to the cycle makes it possible to obtain desalinated water from solutions with a wide spectrum of salt content. To melt crystalline hydrates, it is possible in installations of this type to use the so-called waste heat (waste hot water, exhaust gases, low-grade steam). To increase the efficiency of installations, the desalination technology is being improved in order to simultaneously extract valuable components from brines - for example, magnesium, iodine, bromine, tungsten - and dispose of the remaining salts.