Federal State Educational Institution of Higher Professional Education

"SIBERIAN FEDERAL UNIVERSITY"

Polytechnical Institute

abstract

Methods for clarifying and softening water.

Use of an IOMS inhibitor.

Head ________________ Yakovenko A.A.

Student TE 06 - 03 ________________ Minaeva D.S

Krasnoyarsk 2009

Water clarification methods.

Water clarification is understood as the release of suspended solids from it during the continuous movement of water through special structures (settlers, clarifiers) at low speeds. At low speeds of water movement, the suspended solids contained in it, the specific gravity of which is greater than the specific gravity of water, settle under the action of gravity, forming a sediment in the sump.

Technological schemes for water treatment are determined in each case depending on the requirements and include the following stages of work:

technological research and preliminary laboratory testing of the reagents used;

selection and calculation of equipment for dosing and mixing reagents;

selection of equipment for thin-layer clarification and suspension compaction;

selection and calculation of fast filters with granular loading, both pressure and open type;

selection of technology and equipment for sludge dehydration with subsequent disposal;

selection of equipment for disinfection by dosing a solution of chlorine reagent (sodium hypochlorite) and quality control of treated water.

Depending on the direction of water movement, sedimentation tanks are divided into horizontal, vertical and radial.

The horizontal settling tank (Fig. 1) is a tank of rectangular section, the longitudinal (longer) axis of which is directed along the movement of water. The clarified water is directed through the pipe 1 to the distribution chute 2, which has a number of holes that serve to more evenly distribute the water flow over the cross section of the sump. The speed of water movement in these holes should not exceed 0.4 m/sec. The clarified water enters another gutter 3 and is discharged from it through a pipe 4 to the filters. Settled particles (sludge) accumulate on the bottom, which should have a slope opposite to the movement of water.

The settling time for horizontal settling tanks is usually taken for a coagulated mixture no more than 4 hours. Horizontal settling tanks for clarification of large amounts of water can be divided in height into several compartments (floors) connected in parallel. The advantages of storey settling tanks (proposed by Prof. P.I. Piskunov) are a small building area and less concrete consumption. Such a sump was built at one of the largest treatment plants in the Soviet Union.

Rice. 1. Scheme of a horizontal sump: 1 - tray; 2 - receiving chamber; 3 - receiving chute; 4 - on the filter; 5 - to remove sediment

Rice. 2. Scheme of a vertical sump 1 - central pipe; 2-tray; 3- outlet pipe; 4 - pipeline for sediment removal

Vertical settling tanks (Fig. 2) are a round in plan, sometimes square, tank with a conical bottom and a central pipe, into which clarified water is supplied from the flocculation chamber.

Upon exiting the central pipe into the sump, the water moves upwards at a low speed and drains already clarified through the side of a concentrically located gutter, from where it is discharged to the filter. The sediment falling to the bottom of the sump is periodically removed.

The water flow rate in the central pipe is taken from 30 to 75 mm/sec. The settling time of water in the sump T = 2 hours. The speed of the upward movement of water is 0.5-0.6 mm/sec.

The diameter of the sump should not exceed 12 m, and the ratio of the diameter to the height of the sump is usually taken no more than 1.5.

Radial settling tanks are round tanks with a slightly conical bottom. Water enters the central pipe and from it is directed in the radial direction to the collection tray along the periphery of the sump. Settling tanks have a shallow depth, the sediment is removed mechanically without disturbing the operation of the settling tank. Radial settling tanks are constructed with a diameter of 10 l * or more at a depth of 1.5-2.5 m (at the wall of the settling tank) to 3-5 m (in the center).

The choice of the type of settling tank depends on the daily capacity of the station, its general layout, terrain, nature of the soil, etc. Vertical settling tanks are recommended for use with a daily capacity of up to 3000 m3. Horizontal settling tanks are used when the station capacity is more than 30,000 m3/day, both in the case of water coagulation and without it.

Radial settling tanks are expedient at high water flow rates (more than 40,000 m3/day). The advantage of these settling tanks in comparison with rectangular horizontal ones is the mechanized removal of sediment without stopping the operation of the settling tank. They are used for high turbidity of river water (with and without coagulation) mainly for clarification of industrial water.

Clarifiers with suspended sludge. The clarification process proceeds much more intensively if the water to be clarified after coagulation is passed through a mass of previously formed sediment, maintained in suspension by current

Rice. 3. Clarifiers: a - original design; b - corridor type: 1 - distribution pipes; 2 - gutters with flooded holes; 3 - working part of the clarifier; 4- protective zone; 5 - outlet tray; 6 - pipe for sediment suction; 7 - precipitation windows; 8-sludge thickener; 9 - pipes for sludge discharge) 10 - pipe for draining clarified water

Such clarifiers provide a higher effect of water clarification than in conventional settling tanks, which is explained by faster coarsening and retention of suspension when coagulated water passes through suspended sediment.

The use of a clarifier with a suspended residue makes it possible, compared with a conventional sedimentation tank, to reduce the consumption of coagulant, reduce the size of structures and obtain a higher effect of water clarification.

The clarifier of the original design is a cylindrical tank with a sludge thickener in its central part (Fig. 3, a). Here, the water with the reagent enters the air separator, then passes down into the perforated distribution pipes 1, and then into the holes of the perforated bottom 2.

Water, passing through the layer of suspended sediment 3, enters the clarification zone 4 and overflows into the discharge troughs. An excess of suspended sediment enters the sludge accumulator 5, from where it is periodically removed to the sewer.

The corridor-type clarifier (see Fig. 3, b) is a rectangular tank. The coagulated water enters the clarifier through pipe 1 and is distributed through perforated pipes 2 in the lower (working) part 3 of the clarifier. The speed of water movement in the working part should be such that the coagulant flakes are in suspension. This layer contributes to the retention of suspended particles. The degree of water clarification is much higher than in a conventional sump.

Above the working part there is a protective zone 4, where there is no suspended layer. Clarified water is discharged by tray 5 and pipes 10 for further processing. Excessive amount of sediment by suction into pipe 6 is discharged through windows 7 to sediment thickener 8, where the sediment is compacted and periodically discharged into the sewer through pipes 9.

The ascending flow rate in the working part of the clarifier is assumed to be 1-1.2 mm/sec.

Water softening methods.

The removal of hardness salts from water, i.e. its softening, must be carried out to feed boiler plants, and the hardness of water for medium and low pressure boilers should be no more than 0.3 mg.eq / l. Softening water is also required for such industries as textile, paper, chemical, where water should have a hardness of not more than 0.7-1.0 mg.eq / l. Softening of water for household and drinking purposes is also advisable, especially if it exceeds 7 mg.eq / l.

The following main methods of water softening are used:

1) reagent method. - by introducing reagents that contribute to the formation of poorly soluble calcium and magnesium compounds and their precipitation;

2) cationite method, in which softened water is filtered through substances that have the ability to exchange the cations (sodium or hydrogen) contained in them for calcium and magnesium cations, salts dissolved in water. As a result of the exchange, calcium and magnesium ions are retained and sodium salts are formed that do not give water hardness;

3) the thermal method, which consists in heating water to a temperature above 100 °, while carbonate hardness salts are almost completely removed.

Often, softening methods are used in combination. For example, some of the hardness salts are removed by the reagent method, and the rest by cation exchange.

Of the reagent methods, the soda-lime softening method is the most common. Its essence is reduced to obtaining, instead of Ca Mg salts dissolved in water, insoluble salts of CaCO 3 and Mg (OH) 2 that precipitate.

Both reagents - soda Na 2 C0 3 and lime Ca (OH) 2 - are introduced into the softened water simultaneously or alternately.

Salts of carbonate, temporary hardness are removed with lime, non-carbonate, constant hardness - soda. Chemical reactions when removing carbonate hardness proceed as follows:

Ca (HC0 3) 2 + Ca (OH) 2 \u003d 2 CaCO 3 + 2H 2 0.

In this case, calcium carbonate CaCO3 precipitates. When magnesium bicarbonate Mg (HC0 3) 2 is removed, the reaction proceeds as follows:

Mg (HCOa) 2 + 2Ca (OH) 2 \u003d Mg (OH) 2 + 2CaCO 3 + 2H 2 0.

Magnesium oxide hydrate Mg(OH) 2 coagulates and precipitates. To eliminate non-carbonate hardness, Na 2 C0 3 is introduced into the softened water. The chemical reactions when removing non-carbonate hardness are as follows:

Na 2 C0 8 + CaS0 4 \u003d CaCO 8 + Na 2 S0 4;

Na 2 CO 3 + CaCl 2 \u003d CaC0 3 + 2NaCl.

As a result of the reaction, calcium carbonate is obtained, which precipitates.

For deep softening, auxiliary measures are used, such as heating the treated water to about 90, while the residual hardness can be increased to 0.2-0.4 mg.eq / l.

Without heating, water treatment is carried out with large excess doses of lime, followed by removal of these excesses by purging the water with carbon dioxide. The last process is called recarbonization.

On fig. 4 shows a diagram of a reagent water softening plant, which includes a device for preparing and dosing reagent solutions, mixers, reaction chambers, clarifiers, and filters.

To soften uniformly supplied water that flows continuously, the same soda and lime solution dispensers are used as in coagulation. If the flow of softened water fluctuates, so-called proportional dispensers are used.

Rice. 4. Scheme of reagent water softening: 1 - reaction chamber (vortex reactor); 2 - clarifier; 3 - quartz filter; 4 - mixer; 5, 6 and 7 - dispensers of reagent solutions; 8, 9 and 10 - tanks for dissolving coagulants and soda for making milk of lime; 11 - tank; 12 - pump; 13 - air separator.

The soda-lime method is suitable for softening water with any ratio of carbonate and non-carbonate hardness.

The disadvantages of the soda-lime softening method are as follows: 1) the water is not softened completely; 2) installations for softening bulky; 3) a careful dosage of soda and lime is necessary, which is difficult to achieve due to the inconstancy of the composition of the softened water and reagents.

The cationic softening method is based on the ability of substances called cationites to exchange the sodium cations Na + or hydrogen H + contained in them for calcium or magnesium cations dissolved in water. In accordance with this, sodium-cationite and hydrogen-sodium are distinguished: cationite methods of water softening.

With the help of cation exchangers, water is softened in an installation consisting of several metal pressure tanks loaded with cation exchange resin (Fig. 5).

Raw water enters the filter through pipes A, B and C; softened water is released through pipe G. When the filter is operating, valves 2 and 5 are open, and the rest (1, 3, 4 and 6) are closed. Wash the filter before regeneration.

To wash the filter, water from tank D is supplied through pipe E and passes through drains from bottom to top. The duration of washing is 20-30 minutes, the intensity is 4-6 l / s per 1 m2. Rinse water from the filters is discharged through pipes C, B, G, with valves 4 and 3 open, and the rest closed.

The regenerating solution of the cation exchanger during regeneration is supplied through pipe B, passes the filter from top to bottom and is discharged through the pipe. In this case valves 1 and 6 are open, the rest (2-5) are closed; the duration of regeneration is about 30-60 minutes, and washing from the regenerating solution is 40-60 minutes.

Rice. 5. Diagram of a cationic water softener

The advantages of the cationite method are as follows: 1) the water softens almost completely; 2) it is necessary to dose only a solution of common salt or sulfuric acid; 3) filters are manufactured in a factory way. The disadvantages of this method include the need for preliminary clarification of water, since colloidal and organic substances envelop grains of cation exchangers and reduce their exchange capacity.

Reagents used in water treatment are introduced into the water in the following places:

a) chlorine (in case of preliminary chlorination) - into the suction pipelines of the pumping station of the first lift or into the conduits supplying water to the treatment station;

b) coagulant - into the pipeline before the mixer or into the mixer;

c) lime for alkalization during coagulation - simultaneously with the coagulant;

d) activated carbon to remove odors and tastes in water up to 5 mg/l - before filters. At high doses, coal should be injected at the pumping station of the first lift or simultaneously with the coagulant into the mixer of the water treatment plant, but not earlier than 10 minutes after the introduction of chlorine;

e) chlorine and ammonia for water disinfection are introduced to treatment facilities and into filtered water. In the presence of phenols in the water, ammonia should be introduced both during preliminary and final chlorination.

The coagulant solution is prepared in solution tanks; from where it should be released or pumped into service tanks. To supply a given amount of coagulant solution to the water, it is necessary to provide for the installation of dispensers.

When using automatic dispensers based on the principle of changing the electrical conductivity of water depending on impurities, lime for alkalization should be introduced after the selection of coagulated water going to the dispenser.

Special types of water purification and treatment include: desalination, desalination, iron removal, removal of dissolved gases from water and stabilization.

Mechanism of action of IOMS inhibitors.

When water is heated during the operation of the heating system, the thermal decomposition of the bicarbonate ions present in it occurs with the formation of carbonate ions. Carbonate ions, interacting with calcium ions present in excess, form the embryos of calcium carbonate crystals. More and more carbonate ions and calcium ions are deposited on the surface of the nuclei, as a result of which crystals of calcium carbonate are formed, in which magnesium carbonate is often present in the form of a substitutional solid solution. Settling on the walls of heat engineering equipment, these crystals coalesce, forming scale (Fig. 6, a).

The main component providing the antiscale activity of all the considered inhibitors are organophosphonates - salts of organic phosphonic acids. When organophosphonates are introduced into water containing calcium, magnesium and other metal ions, they form very strong chemical compounds - complexes. (Many modern inhibitors contain organophosphonates already in the form of complexes with transition metals, mainly with zinc.) Since one liter of natural or industrial water contains 1020–1021 calcium and magnesium ions, and organophosphonates are introduced in an amount of only 1018–1019 molecules per liter of water, all molecules of organophosphonates form complexes with metal ions, and complexons as such are not present in water. Complexes of organophosphonates are adsorbed (precipitated) on the surface of calcium carbonate crystal nuclei, preventing further crystallization of calcium carbonate. Therefore, when 1–10 g/m3 of organophosphonates are introduced into water, scale does not form even when very hard water is heated (Fig. 6b).

Complexes of organophosphonates can be adsorbed not only on the surface of crystal nuclei, but also on metal surfaces. The resulting thin film hinders the access of oxygen to the metal surface, as a result of which the metal corrosion rate decreases. However, the most effective metal protection against corrosion is provided by inhibitors based on complexes of organic phosphonic acids with zinc and some other metals, which were developed and put into practice by Professor Yu.I. Kuznetsov. In the surface layer of the metal, these compounds can decompose with the formation of insoluble compounds of zinc hydroxide, as well as complexes of a complex structure, in which many zinc and iron atoms participate. As a result of this, a thin, dense film is formed that is firmly adhered to the metal and protects the metal from corrosion. The degree of metal protection against corrosion when using such inhibitors can reach 98%.

Modern preparations based on organophosphonates not only inhibit scale and corrosion, but also gradually destroy old deposits of scale and corrosion products. This is explained by the formation of surface adsorption layers of organophosphonates in the scale pores, the structure and properties (for example, thermal expansion coefficient) of which differ from the structure of scale crystals. The fluctuations and temperature gradients arising during the operation of the heating system lead to wedging of crystalline scale aggregates. As a result, the scale is destroyed, turning into a fine suspension, which is easily removed from the system. Therefore, when introducing preparations containing organophosphonates into heating systems with a large amount of old deposits of scale and corrosion products, it is necessary to regularly drain sediment from filters and sumps installed at the lowest points of the system. The sludge should be drained, depending on the amount of deposits, 1-2 times a day, based on feeding the system with clean, inhibitor-treated water in the amount of 0.25-1% of the water volume of the system per hour. It should be noted that with an increase in the concentration of the inhibitor above 10–20 g/m3, the scale is destroyed with the formation of very coarse suspensions that can clog the bottlenecks of the heating system. Therefore, an overdose of the inhibitor in this case threatens to clog the system. The most effective and safe cleaning of heating systems from old deposits of scale and corrosion products is achieved using preparations containing surfactants, for example, the KKF composition.

a) b)

Rice. 6. Section of the intra-quarter 89 mm hot water pipeline:

a - after two years of operation on water with a hardness of 8–12 meq/dm3;

b - six months after the start of water treatment with an IOMS-1 inhibitor.

Technological schemes and structural elements of chemical water softening plants

Thermochemical method of water softening

Water softening by dialysis

Magnetic water treatment

Literature

Theoretical foundations of water softening, classification of methods

Water softening refers to the process of removing hardness cations from it, i.e. calcium and magnesium. In accordance with GOST 2874-82 "Drinking water" water hardness should not exceed 7 mg-eq / l. Separate types of industries impose requirements on process water for its deep softening, i.e. up to 0.05.0.01 mg-eq / l. Commonly used water sources have a hardness that meets the standards of domestic and drinking water, and do not need softening. Water softening is carried out mainly during its preparation for technical purposes. Thus, the hardness of water for feeding drum boilers should not exceed 0.005 mg-eq / l. Water softening is carried out by methods: thermal, based on heating water, its distillation or freezing; reagent, in which the ions in the water Ca ( II ) and mg ( II ) bind with various reagents into practically insoluble compounds; ion exchange, based on the filtration of softened water through special materials that exchange the ions included in their composition Na ( I) or H (1) into Ca (II) ions and mg ( II ) contained in the dialysis water; combined, representing various combinations of the above methods.

The choice of water softening method is determined by its quality, the required depth of softening and technical and economic considerations. In accordance with the recommendations of SNiP when softening groundwater, ion-exchange methods should be used; when softening surface water, when water clarification is also required, the lime or lime-soda method is used, and when the water is deeply softened, subsequent cationization. The main characteristics and conditions for the use of water softening methods are given in Table. 20.1.

softening water dialysis thermal

To obtain water for household and drinking needs, only a certain part of it is usually softened, followed by mixing with the source water, while the amount of softened water Q y determined by the formula

where J o. and. - total hardness of the source water, mg-eq/l; F 0. s. - total hardness of water entering the network, mg-eq / l; J 0. y. - softened water hardness, mg-eq/l.

Water softening methods

Thermal method of water softening

It is advisable to use the thermal method of water softening when using carbonate water used to feed low-pressure boilers, as well as in combination with reagent methods of water softening. It is based on the shift of the carbon dioxide equilibrium when it is heated towards the formation of calcium carbonate, which is described by the reaction

Ca (HC0 3) 2 -\u003e CaCO 3 + C0 2 + H 2 0.

The equilibrium is shifted by a decrease in the solubility of carbon monoxide (IV), caused by an increase in temperature and pressure. Boiling can completely remove carbon monoxide (IV) and thereby significantly reduce calcium carbonate hardness. However, this hardness cannot be completely eliminated, since calcium carbonate, although slightly (13 mg / l at a temperature of 18 ° C), is still soluble in water.

In the presence of magnesium bicarbonate in water, the process of its precipitation occurs as follows: first, a relatively well-soluble (110 mg / l at a temperature of 18 ° C) magnesium carbonate is formed

Mg (HCO 3) → MgC0 3 + C0 2 + H 2 0,

which is hydrolyzed during prolonged boiling, as a result of which a precipitate of slightly soluble precipitates (8.4 mg / l). magnesium hydroxide

MgC0 3 + H 2 0 → Mg (0H) 2 + C0 2.

Consequently, when water is boiled, the hardness due to calcium and magnesium bicarbonates decreases. Boiling water also reduces the hardness determined by calcium sulfate, the solubility of which drops to 0.65 g/l.

On fig. 1 shows a thermal softener designed by Kopiev, which is characterized by a relative simplicity of the device and reliable operation. The treated water, preheated in the apparatus, enters through the ejector to the outlet of the film heater and is sprayed over vertically placed pipes, and flows down through them towards the hot steam. Then, together with the blowdown water from the boilers, it enters the clarifier with suspended sediment through the central supply pipe through the perforated bottom.

Carbon dioxide and oxygen released from the water, together with excess steam, are discharged into the atmosphere. The calcium and magnesium salts formed during the heating of water are retained in the suspended layer. After passing through the suspended layer, the softened water enters the collector and is discharged outside the apparatus.

The residence time of water in the thermal softener is 30.45 min, the speed of its upward movement in the suspended layer is 7.10 m/h, and in the openings of the false bottom 0.1.0.25 m/s.

Rice. 1. Thermal softener designed by Kopiev.

15 - discharge of drainage water; 12 - central supply pipe; 13 - false perforated bottoms; 11 - suspended layer; 14 - sludge discharge; 9 - collection of softened water; 1, 10 - supply of initial and removal of softened water; 2 - purge of boilers; 3 - ejector; 4 - evaporation; 5 - film heater; 6 - steam discharge; 7 - an annular perforated pipeline for water drainage to the ejector; 8 - inclined separating partitions

Reagent methods of water softening

Water softening by reagent methods is based on its treatment with reagents that form sparingly soluble compounds with calcium and magnesium: Mg (OH) 2, CaCO 3, Ca 3 (P0 4) 2, Mg 3 (P0 4) 2 and others, followed by their separation in clarifiers , thin-layer settling tanks and clarification filters. Lime, soda ash, sodium and barium hydroxides and other substances are used as reagents.

Water softening by liming used for its high carbonate and low non-carbonate hardness, as well as in the case when it is not required to remove salts of non-carbonate hardness from water. Lime is used as a reagent, which is introduced in the form of a solution or suspension (milk) into preheated treated water. Dissolving, lime enriches water with OH - and Ca 2+ ions, which leads to the binding of free carbon monoxide (IV) dissolved in water with the formation of carbonate ions and the transition of hydrocarbonate ions to carbonate:

C0 2 + 20H - → CO 3 + H 2 0, HCO 3 - + OH - → CO 3 - + H 2 O.

An increase in the concentration of CO 3 2 - ions in the treated water and the presence of Ca 2+ ions in it, taking into account those introduced with lime, leads to an increase in the solubility product and precipitation of poorly soluble calcium carbonate:

Ca 2+ + C0 3 - → CaC0 3.

With an excess of lime, magnesium hydroxide also precipitates.

Mg 2+ + 20Н - → Mg (OH) 2

To accelerate the removal of dispersed and colloidal impurities and reduce the alkalinity of water, coagulation of these impurities with iron (II) sulfate is used simultaneously with liming. FeS0 4 * 7 H 2 0. The residual hardness of softened water during decarbonization can be obtained by 0.4.0.8 mg-eq / l more than non-carbonate hardness, and the alkalinity is 0.8.1.2 mg-eq / l. The dose of lime is determined by the ratio of the concentration of calcium ions in water and carbonate hardness: a) at the ratio [Ca 2+ ] /20<Ж к,

b) with the ratio [Ca 2+] / 20 > W to,

where [СО 2 ] is the concentration of free carbon monoxide (IV) in water, mg/l; [Ca 2+ ] - concentration of calcium ions, mg/l; Zhk - carbonate hardness of water, mg-eq / l; D to - dose of coagulant (FeS0 4 or FeCl 3 in terms of anhydrous products), mg / l; e to- equivalent mass of the active substance of the coagulant, mg/mg-eq (for FeSO 4 e k = 76, for FeCl 3 e k = 54); 0.5 and 0.3 - an excess of lime to ensure a greater completeness of the reaction, mg-eq / l.

Hard water is water that contains a large amount of hardness salts, namely calcium and magnesium.

What's wrong with hard water

Hard water is not suitable for many technological processes. It is unpleasant in taste, it is bad to wash and wash in it, since washing requires an increased consumption of detergents, and when washing, plaque remains on the hair and skin. Hard water is not suitable for the needs of the food industry due to the bitter taste and due to the fact that salts precipitate during storage of food. And the quality of products suffers when using bad drinking water.

Hard water causes trouble for all industrial enterprises, as it quickly clogs water pipes with precipitation and scale.

Salt deposits are the scourge of heating equipment, which hopelessly fails, and also requires a significant excessive consumption of fuel, since the efficiency of heat exchange processes drops sharply when a poorly heat-conducting salt layer is deposited on the surface of the heat exchangers.

Softened water is required in boiler equipment, in kettles and washing machines, in heat pumps and district heating utilities. Even water with a small amount of hardness salts is not suitable for high-pressure boilers, since the failure of these installations can lead to a serious accident. In practice, it turns out to be much cheaper to carry out a set of measures to remove hardness salts from water than to repair and replace pipe, heating and boiler equipment.

Water softening is also required to obtain ultrapure water for laboratory and analytical needs, for pharmaceutical and medical enterprises. Mitigation is the first stage of water purification for these purposes.

Water softening methods

The main methods of water softening today are:

Softening with ion exchange resins;
- use of membranes;
- reagent (chemical);
- magnetic water treatment;
- thermal;
- electrochemical;
- combination of several methods in one installation.

Water softening with ion exchange resins- the most popular method at the moment for the needs of utilities and the food industry. The principle of purification is based on the filtration of water through ion-exchange resins, passing through which calcium and magnesium ions are replaced by sodium and hydrogen ions. The regeneration of resins is carried out using a solution of common salt - a cheap and affordable reagent. The cleaning process itself is easily automated. The ion-exchange method is often used in combined installations for deep water purification.

Membrane method water softening is the most technologically advanced, although expensive. It allows not only to soften water, but also to purify from most chemical, organic impurities, heavy metal ions, chlorine and organochlorine compounds, bacteria, suspensions. The principle of purification - water is passed through special membrane materials with a certain pore size.

Water softening with reagents It is based on the addition of special reagents to water, which form insoluble or slightly soluble compounds with calcium and magnesium cations. Most often, slaked lime and soda are used on an industrial scale. The disadvantages of this method is the high salinity of wastewater, which require additional treatment; the need for careful, most often manual control of the process and the high alkaline reaction of the resulting water. Chemical methods are not suitable for softening drinking water. As a rule, these methods are the first step for combined water treatment.

magnetic way water softening is based on the transfer of hardness salts into a modified state, in which they crystallize not into dense calcite, but into unstable aragonite, which is not deposited on the surfaces of pipes and heat exchangers, but is removed with water.

Thermal Water softening is based on the fact that when the temperature of hard water rises above 120 ° C, calcium and magnesium salts precipitate. Water can be purified also by freezing and distillation. In industry distillation is rarely used and only when there is access to cheap energy for heating, but in laboratories distillers are often used for deep water purification.

Electrochemical method Water softening is based on several simultaneous processes occurring at the time of the passage of water between the electrodes (electrophoresis, electrolysis, polarization, etc.), which lead to the formation of insoluble magnesium and calcium salts.

The specific water softening method is usually determined depending on the quality of the source water, the desired quality of the resulting water, the required plant capacity and the acceptable financial costs.

We can offer our customers who have a need for water softening to buy the PHS AQUA 10 Water Distiller, Vladipor membrane filters and

" and "Chemical reagent methods of water softening" section "Water" and subsection "" we touched on the topic of combating hardness salts and scale. In previous articles, we examined the actual definition of the word "water softening" and considered that there are several ways of softening - physical, chemical, extrasensory.And also touched upon such reagent methods of water softening as ion exchange and the dosage of antiscalants (antiscale formers).In this article we offer you two subsections - a little about extrasensory methods and a little more about physical methods of water softening.

Psychic and physical methods of water softening are not fully understood and understood. This is probably why very often the psychic way of dealing with hard water is confused with the physical way of dealing. And, accordingly, they lose money, time and faith in people. Both for the purchase of psychic gadgets, and for the repair of equipment that they did not protect from scale. By the way, for a good understanding of the article, we recommend that you first study the materials of the articles "Hard water" and "", where the main definitions used in this article are given (such as water softening, scale, hardness, hardness salts, etc.)

Psychic methods of water softening.

So, psychic methods are easily confused with physical ones. About the same as the ganzfeld effect with magic. So, for example, water treatment with a magnetic field. This is both a qualitative way to deal with scale, and a useless extrasensory way of cleaning and structuring water.

The difference between physical and extrasensory methods is very simple - if a thing costs a little money (up to 100 USD on average), and it is promised that it will complete a lot of tasks (such as: it will purify water from all substances, remove scale, heal and give youth, structures, accelerates the growth of plants and hair, removes spoilage, etc.), then this is a psychic method of water purification. We will not dwell on extrasensory methods in detail, they are described in various sources (for example, here), since the sense from them is only a hundredth of what was promised.

By the way, recently there has been a tendency to increase the price of such softening structurers. So you can run into a very expensive fake, which is declared as protection against scale. However, usually devices that can really physically help with scale do not have additional structuring functions.

So, if you want to do extrasensory structuring, then you need to purchase a special device. If you need to soften the water physically, you need to purchase a special device. But not complex. Although ... As anyone likes it 🙂 And we will move on to physical ways to deal with scale.

As mentioned earlier, there are several definitions of the term "water softening", depending on the stage at which the impact occurs -

• at the stage of combating the causes of water hardness or
• at the stage of dealing with the consequences of using hard water.

The previous methods - ion exchange - are aimed at combating the causes of water hardness. That is, either calcium and magnesium salts are removed from the water, which leads to the creation of soft water.

Physical methods of water softening are aimed at coping with the consequences of hard water - scale.

Accordingly, physical softening methods do not imply soft water in the first sense (water without hardness salts at all). The result of the work of physical water softening is water that has retained all its hardness salts, but does not harm pipes and boilers - that is, it does not form scale. However, hard water after physical treatment changes its properties - and, as a result, ceases to form scale. That is, it ceases to be rigid. And it becomes soft. Of course, if we were doing scientific research, we would introduce a difference in the terms "soft water", that is, water in which there are no hardness salts in principle, and "softened water", which does not form scale, but may contain hardness salts. However, these are terminological nuances that are not of interest to us. Us actually physical methods of water softening.

There are such basic physical ways to deal with scale:

1. Treatment of water with a magnetic field.
2. Treatment of water with an electric field.
3. Ultrasonic water treatment.
4. Water treatment using low-current current pulses.
5. Thermal softening method (normal boiling water).

And we will begin to gradually characterize the physical ways to deal with hard water. We may not cover everything at once in one article, but a series of articles will definitely include the characteristics of each of the methods. Let's start with water treatment with a magnetic field, since this type of physical descaler is most often confused with psychic water softening.

Treatment of water with a magnetic field is a complex and controversial issue. Without going into details, we can say that effective physical softening of water using a magnetic field is possible only when a huge number of factors can be taken into account simultaneously. It:

1. magnetic field strength,
2. water flow rate,
3. water composition:
   • ionic (including the presence of iron and aluminum ions that impair the physical treatment of water),
   • molecular (including large organic molecules, especially those with the ability to form complexes),
   • mechanical impurities (including rust),
   • ratio of para- and diamagnetic components,
   • dissolved oxygen and other gases
   • the presence of non-equilibrium systems, etc.
4. water temperature during and after treatment,
5. processing time,
6. Atmosphere pressure,
7. water pressure,
8. etc.

All these and many other factors affect the efficiency of magnetic water treatment. Thus, an insignificant change in the composition of water should be compensated by changes in the specified parameters (for example, water velocity and magnetic field intensity). All changes must be monitored and responded to immediately, since the effectiveness of the physical softening of water using a magnetic field will change in an unknown direction.

But it is possible, and magnetic water treatment is successfully used in many boiler houses. First of all, this happens because in boiler houses the constancy of most of the listed factors is observed - both the flow of water, and the composition of water, and the temperature of the water, and pressure, etc.

However, this is practically NOT possible to repeat at home. And when you have a desire to buy a magnet for a pipe in order to save your house from scale, then think a lot of times, and first of all, consider whether you can organize not only the constancy of the indicators described above, but also find their optimal combination through experiments.

If not, then treating water with a magnetic field in the form of magnets is not for you, and you will get nothing but wasted money on buying a magnet and repairing equipment and pipes. In another way, it can be said like this: the probability that a tube magnet will help you is less than 10%. That is, at home, a constant magnetic field approaches extrasensory water softening.

In order to compensate for the variability of water parameters during physical treatment, more modern methods of physical softening are used - for example, using an electronic water softener.

Thus, do not confuse psychic water softening, limited area physical softening, and modern physical water softening.

Which will be discussed in the sequel.

From advertising, we know that too hard water leads to the appearance of scale and the rapid failure of washing machines. Manufacturers don't lie. Excessive rigidity harms not only household appliances, but also health: it makes hair thin and brittle, accelerates skin aging, contributes to the development of diseases of the kidneys and the genitourinary system, and creates an additional load on blood vessels. Depending on the situation, you can soften the water in different ways, in this article we will review the most affordable home remedies.

Theory. Water hardness is a parameter characterizing the concentration of calcium and magnesium salts in the composition. It is measured in units of mol / m3 (moles per cubic meter) or degrees of hardness (accepted in Russia) - mg-eq / l (milligram equivalent per liter). The higher this figure, the worse.

According to the studies of the World Health Organization (WHO), normal water hardness is 1-2°F (mg-eq/l). In Russia, an indicator of up to 7 ° F is considered an acceptable norm.

According to the hardness value, water is divided into:

• soft (0-2 ° W) - in nature it is found in swampy areas with peat bogs, and melted snow that is not polluted by other substances also falls into this group. Interestingly, it is very difficult to wash off the soap with soft water.
• medium (2.1-7 ° W) - the most common;
• hard (7-10 ° W) - harmful and dangerous to health;
• superhard (more than 10°F) - in natural conditions it is found in lakes of karst caves, it is impossible to drink such water.

Depending on the substances contained, the hardness of water is:

• constant - caused by the presence of chlorides, phosphates, silicates, sulfates and nitrates of magnesium, calcium in water, which do not decompose when boiled, basically these substances are removed only by filters;
• temporary - occurs in most cases, due to magnesium and calcium bicarbonates, which decompose when heated, forming scale deposits on pipes and heating devices, which leads to increased energy costs and breakdown.

How to determine the hardness of water

The easiest option is to look at a special map of water hardness in your region. You can also use a conductometer (TDS-meter) - a special device that measures the electrical conductivity of water, popularly called a "salt meter". The higher the value on the screen, the harder the water, because it contains a lot of salts. The exact ratio can be calculated from the tables.

Signs of increased water hardness:

• soap and washing powder give very little foam;
• persistent scale in the kettle after several boils;
• after washing dishes, stains appear;
• water has a slightly bitter taste (not all people feel it);
• after settling, a white coating appears on the walls of water containers.

Water hardness unit calculator

°F (Russia) °DH (Germany) °Clark (UK) °F (France) ppm (USA)

Methods to soften water

1. Boiling. The easiest affordable way to get rid of temporary stiffness without the use of chemicals and complex devices. At high temperatures, bicarbonates and calcium sulfate decompose, precipitating on the bottom of the dishes and heating elements. Softened water is suitable for any purpose: drinking, washing, washing, etc.

Bring the water to a boil, leave for 2-3 minutes, then cool to the desired temperature.

Flaws:

• only the temporary hardness of water is partially reduced;
• limited - it is very difficult to provide all domestic needs with boiled water;
• after some time, due to a layer of scale, heating systems and containers have to be changed or cleaned;
• when boiling water, useful substances evaporate;
• heating requires a significant amount of energy.

2. Settling. After 1-2 days in a place protected from direct sunlight, it softens water from wells and wells, intended for watering flowers and indoor plants. It can be used for drinking water treatment, but only if the initial hardness is only slightly higher than normal.

3. Freezing. An effective method that does not change the structure of water, as a result of which all useful substances remain in the composition. Put water in the freezer, when ice appears on the walls of the container, drain the liquid in the center.

Use the melted ice as drinking water or for watering flowerpots.

Disadvantage: it is difficult to prepare large volumes of water with this method.

4. Food and soda ash. Thanks to its chemical properties, baking soda softens water and reduces acidity.

Add 2 teaspoons of food or 1 teaspoon of soda ash to 10 liters of water, mix well and wait for sediment to appear at the bottom. While cooking, add 1 teaspoon of baking soda to 3 liters of water so that cereals and vegetables boil better.

Flaws:

• water softened with soda cannot be used as drinking water (except for boiling);
• difficulty in the constant processing of large volumes of water.

5. Vinegar and citric acid. Partially reduce hardness, but significantly increase acidity, as a result of which these products are not recommended for drinking water. Often they are used for cosmetic purposes.

To soften the water for washing your hair, add 1 tablespoon of vinegar (1 teaspoon of citric acid or the juice of one lemon) to 2 liters of water, mix. Let stand 4-5 minutes before use.

6. Rock (cooking) salt. It is also sodium chloride, which dissolves calcium and magnesium salts contained in water, preventing the appearance of scale on heating devices. Due to changes in chemical composition and taste, this method is not recommended for drinking.

Basically, salt softens water intended for dishwashers. For ease of use, manufacturers supply salt in the form of granules and tablets, but in most cases, the composition of the proposed substance is no different from table salt.

7. Chemicals. First of all, these are the well-known brands Calgon, Finish and others, which are sold in the form of powder or tablets. Apply according to instructions. Sold in household chemical stores.

Disadvantage: soften water only for washing.

8. Filters. Versatile systems designed to quickly soften large amounts of hard water and remove harmful impurities. They can operate independently or be connected to the water supply. They differ in design and principle of operation.

Types of water hardness reduction systems:

• filter jug- designed for a volume of 1-3 liters, suitable for drinking water purification, tea or coffee preparation. Works with a special cartridge. Depending on the intensity of use and the initial hardness of the water, it lasts up to 2 months, then it requires replacement of the filter cartridge.
• Ion exchange systems- filter and soften water of any hardness with the help of special ion-exchange resins and saline solution (substances are in different tanks). These filters are characterized by high performance and relatively easy maintenance. Disadvantages: not suitable for drinking water, require periodic replacement of reagents and connection to the sewer.
• Magnetic and electromagnetic softeners- are installed on highways or on water pipes in the form of overlays. Under the influence of a magnetic or electromagnetic field, hardness salts lose their ability to be deposited in the form of scale and drain into special sedimentation tanks. Disadvantage: not suitable for drinking water treatment.