Home Natural farming Current state and development of water treatment technologies. State and prospects for the development of industrial water treatment. Water purification technology for heating and ventilation purposes

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Current state and development of water treatment technologies. State and prospects for the development of industrial water treatment. Water purification technology for heating and ventilation purposes

Industrial water treatment is an important stage in the production of many types of products. Consuming various drinks every day, we don’t even think about how many stages of filtration the water from which they are made goes through. No less important is the industrial treatment of wastewater, which brings a lot of harmful chemicals into natural sources. The water that is supplied to central water supply systems is also subjected to industrial preparation.

Every year the problem of shortage of drinking water becomes more acute. Already, about 1/6 of the Earth’s inhabitants do not have access to it. Among the reasons for fresh water shortage:

high consumption exceeding needs;
growing population;
melting glaciers;
pollution of surface waters by household and industrial waste.

The main sources of pollution are municipal and industrial wastewater. The former contain various harmful bacteria that can cause serious diseases. The second is the accumulation of all kinds of chemicals: acids and alkalis, heavy metals, petroleum products, etc.

Industrial water treatment is divided into water treatment and water purification. Water treatment refers to the purification and disinfection of water for its purpose. At the water treatment stage, clarification, softening, degassing, deodorization and disinfection occur.

Clarification refers to the removal of various suspended and dissolved particles that cause color and turbidity. Softening is facilitated by the removal of calcium and magnesium salts. Thanks to degassing, various dissolved gases, such as hydrogen sulfide, are eliminated from the liquid. Disinfection leads to the destruction of pathogenic microflora, and at the deodorization stage, extraneous unpleasant odors go away.

To achieve the above goals, three groups of methods are used:

Physical.
Chemical.
Physico-chemical.

Physical cleaning methods (methods)

Physical methods of industrial water purification remove impurities without the use of reagents. These methods are based on a variety of physical phenomena. This group includes:

Mechanical filtration.
Ultrafiltration.
Nanofiltration.
Microfiltration.

Mechanical water filtration

Industrial water purification by mechanical filtration is the simplest method; it is carried out at the primary stage of water treatment. Mechanical filters are divided into coarse filters and fine filters.

Coarse filters are installed at the water intake stage. The principle of operation is that the sieve prevents the passage of large particles of impurities: sand, clay, organic matter, calcium and magnesium salts. Popularly, such filters are called “mud filters”. They are a mandatory element of water treatment. Thanks to them, color and turbidity are destroyed, and unpleasant odors go away.

Fine filters are based on a cartridge with a sorbent, through which water is purified from various gases, chemical compounds, and some microorganisms.

Among the methods of physical influence, membrane technologies have gained particular popularity. The main difference between such filters from each other is the throughput of the membrane.

Reverse osmosis systems

The most effective membrane technology is water treatment through. The pore size in a reverse osmism membrane is less than 0.0001 microns. Such a membrane allows water and oxygen molecules to pass through, while retaining various impurities. Reverse osmium filters are capable of purifying water at the molecular level almost to a distilled state.

The solution must approach the membrane in reverse osmosis installations free of mechanical impurities. Therefore, reverse osmosis systems consist of several elements, the main ones being:

Pre-filter that removes primary dirt.
Fine filter with sorbing material.
Membrane.
Mineralizer. In addition to harmful contaminants, the reverse osmism membrane also destroys necessary for a person minerals, the balance of which is restored by the mineralizer. In addition to this cartridge, an ionizer and a softening unit can be added to the system.

The disadvantages of this method include low productivity, the size of the installation and the loss of water, which merges with impurities.

Nanofiltration

The second place in terms of throughput is occupied by a nanofiltration membrane, the pore size of which is 0.001-0.002 microns. In fact, these filters are a type of reverse osmosis; they remove bacteria and viruses, hardness salts, nitrites, nitrates and other impurities.

It is used in the food, pharmaceutical, paint and varnish and petrochemical industries.

The advantage of this method, unlike reverse osmosis, is the preservation of useful minerals during the purification process. That is why water purified using this technology is more preferable in the production of drinks.

In addition, the nanofiltration process more economical, since it occurs at lower pressure.

Ultrafiltration

The ultrafiltration method is similar in principle to reverse osmosis systems. Water passes through a membrane, which retains microorganisms, algae, suspended particles, and helps eliminate turbidity and color. The pore size of such a membrane is 0.002...0.1 microns, which is larger than the pore size in reverse osmosis and nanofiltration membranes. Ultrafiltration does not help remove metal salts, due to which the water needs additional softening.

We said above that this method is similar in principle to reverse osmosis, but there are also differences.

The membrane in ultrafiltration consists of multichannel fibers, which are made from modified polyestersulfone. The number of fibers is several tens of thousands. The reverse osmosis membrane is made of synthetic materials and consists of a cylinder of film wound into a roll.
With ultrafiltration, contaminants remain inside the membrane. In the case of reverse osmosis, after purification, two streams of water come out of the membrane. The first is the purified liquid, the second is the concentrate, which is drained. Thus, in reverse osmism systems, up to 1/3 of the water is lost during purification.
Ultrafiltration, unlike reverse osmosis, does not remove hardness salts.

Ultrafiltration technological chain

The liquid passes through a coarse filter to remove mechanical impurities that could damage the membrane.
Then it interacts with the membrane.
Bypassing the module, water enters the tank clean water, which is also called a backwash tank - water from it is used to wash the membranes from surface contaminants.

The advantages of ultrafiltration are:

compactness of equipment;
maximum disinfection and removal of suspended matter;
no use of chemical reagents, although sometimes coagulants can be added to it at the stage of supplying water to the purification system.

Microfiltration

Of the membrane methods, microfiltration has a module with the most large pores, the size of which is 0.1 to 1 microns. Often used as a preliminary stage of purification before reverse osmosis or nanofiltration, it removes mechanical impurities as much as possible.

Chemical methods (methods) of water purification

The principle of operation of chemical methods is to add special reagents to water that help purify it.

Chlorination

The disinfecting effects of chlorine were discovered back in the 19th century. In 1846, doctors at one of the hospitals in Vienna began rinsing their hands with chlorine water. This marked the beginning of the use of chlorine as a disinfectant.

Chlorine is a strong oxidizing agent, interacting with water to form hypochlorous acid, which destroys bacteria. To achieve the effect, it is necessary to ensure contact of water with chlorine for at least 30 minutes. Effect of exposure hypochlorous acid can persist for a long time after immediate treatment; for this it is necessary to introduce chlorine in excess. The dose of the reagent in each case is calculated individually. It is important not to overdo it with excess, since in large quantities chlorine can lead to problems in the functioning of the body; the compounds formed by this substance are especially dangerous. For example, trihalomethanes cause asthma symptoms.

There are several types of chlorination:

preliminary;
finishing

Pre-chlorination is carried out at the water intake stage. The purpose of the reagent at this stage is not only to destroy bacteria, but also to remove metals from the water by oxidizing them; chlorine also disinfects cleaning equipment.

Final chlorination is used at the last stage of preparation for disinfection purposes.

Depending on the dose of the administered reagents, chlorination occurs:

normal;
rechlorination;
combined.

Normal chlorination used for water purification under good sanitary and chemical-physical conditions.

Rechlorination used in cases of severe contamination of water intake sources, when normal chlorination is powerless against pathogenic microflora. The dose of the reagent is administered in excess, which can lead to changes in the organoleptic characteristics of the water. Residual chlorine is removed by dechlorination. For this purpose, methods of non-pressure aeration, coagulation or water filtration through activated carbon are used.

Combined methods involve treating water with chlorine in combination with other reagents: silver, copper, magnesium, etc. They are used to increase the impact of chlorine, as well as to provide a prolonging effect.

The advantages of chlorination include:

efficiency;
ease of use;
cost-effectiveness of the method;
comprehensive in water purification.

Among the disadvantages are:

serious requirements for storage and transportation of chlorine-containing compounds;
the formation of foreign compounds that, if they enter the human body, pose a serious threat;
resistance of a number of microorganisms to the effects of chlorine.

Ozonation

Ozonation is one of the modern methods of water treatment and wastewater treatment. Used in the food, chemical and medical industries.

Ozone is a strong oxidizing agent, has a destructive effect on bacteria, viruses, fungi, metals and various chemical compounds, thereby promoting discoloration, deodorization and neutralization of water. It has been proven that most known microorganisms are not resistant to the influence of gas.

Having a short decay period, ozone does not precipitate, but is converted into oxygen, which makes water useful. The almost instantaneous disintegration of gas molecules is at the same time a serious drawback of ozonation, since re-contamination of the water is possible within 15-20 minutes after treatment. Some sources indicate that ozone helps to “awaken” dormant microorganisms.

Significant disadvantages of the method include:

Corrosive activity of water treated with ozone.
Danger in case of reagent overdose and serious safety precautions during the cleaning process.
The high cost of a special installation - an ozonizer.

Deferrization

Equipment for iron removal deserves special attention, since iron in a dissolved state clogs industrial equipment, as a result of which it quickly breaks down. The deferrization filters are based on a special material “Greensand”, which is fine-grained sand coated with manganese dioxide. It is magnesium dioxide that oxidizes iron molecules, which then precipitate. The deferrization filter is an integral part of modern water filtration installations.

Physico-chemical methods of water purification

Physico-chemical methods combine cleaning with reagents and mechanical removal of impurities. The most common methods in this group include:

adsorption;
coagulation;
flotation.

Adsorption

Adsorption refers to the process of absorption of contaminant molecules by the surface of an adsorbent - a solid with a porous surface. One of the most popular adsorbents is activated carbon, which is capable of purifying water from hydrocarbons, petroleum products, chlorine and phosphorus, as well as stimulating the decomposition of ozone and phosphorus.

Activated carbon filters are often used for final water purification. They are an indispensable element of almost any filtration system. The disadvantages of carbon filters include the rapid clogging of the cartridge, which requires its frequent replacement.

A type of adsorption is ion exchange. Filters based on ion exchange contain a cartridge with a resin that contains sodium ions. Passing through such a filter, water with a high salt content is softened. Salts in water replace sodium ions ready for exchange, due to which the water after passing through such a filter turns out to be soft and saturated with sodium.

Unfortunately, ion exchange filters clog quickly and require frequent replacement of cartridges.

Coagulation

The coagulation method is based on the fact that special substances - coagulants - attract contaminants - metal salts, sand, clay, and then precipitate in the form of flakes. After settling, such water is either further purified through filtration or drained. The method has become widespread in cleaning at industrial enterprises.

Coagulants can be aluminum sulfate, ferric sulfate and ferric chloride, potassium alum, sodium aluminate.

A type of coagulation is flocculation. Unlike coagulation, the adhesion of particles occurs not only at the moment of their direct contact, but also in the process of indirect contact of molecules.

Flotation

The flotation method is actively used for wastewater treatment in industry. Effective for . The principle of operation is based on the addition of dispersed air to the water, under the influence of which contaminant molecules accumulate on the surface of the water in the form of white foam, after which they are removed with special equipment. After flotation, the water undergoes additional purification through sorption.

The advantages of flotation include:

Cost-effectiveness of the method.
Simplicity of design.
Fast wastewater treatment.
Possibility of removing petroleum products.

Industrial filters for water purification: types, differences, prices

Above we said a lot about methods of industrial water treatment and wastewater treatment. Let's try to classify them depending on the type of pollution.

Removal of mechanical impurities - mechanical and sorption filters, microfiltration.
Disinfection – all membrane methods, except microfiltration (reverse osmosis, nanofiltration, ultrafiltration), ozonation.
Iron removal – chlorination, ozonation, Greensand material
Hydrogen sulfide removal – pressure and non-pressure aeration, chlorination, ozonation, adsorption.
Removal of organics, chlorine, ozone - adsorption, coagulation
Removal of petroleum products - flotation units.
Softening – ion exchange, reverse osmosis.

The cost of industrial filters depends on the complexity of installation and the materials used, so the price in each specific case must be clarified individually.

Water is absolutely necessary for human life and all living things in nature. Water covers 70% of the earth's surface, these are: seas, rivers, lakes and groundwater. During its cycle, determined by natural phenomena, water collects various impurities and contaminants that are contained in the atmosphere and on the earth’s crust. As a result, water is not absolutely pure and pure, but often this water is the main source both for domestic and drinking water supply and for use in various industries (for example, as a coolant, working fluid in the energy sector, solvent, feedstock for receiving products, food, etc.)

Natural water is a complex disperse system, which contains large quantities of various mineral and organic impurities. Due to the fact that in most cases the sources of water supply are surface and groundwater.

Composition of ordinary natural water:

suspended substances (colloidal and coarse mechanical impurities of inorganic and organic origin);
bacteria, microorganisms and algae;
dissolved gases;
dissolved inorganic and organic matter(both dissociated into cations and anions, and undissociated).

When assessing the properties of water, it is customary to divide water quality parameters into:

physical,
chemical
sanitary and bacteriological.

Quality means compliance with the standards established for a given type of water production. Water and aqueous solutions are very widely used in various industries, public utilities and agriculture. Requirements for the quality of purified water depend on the purpose and area of application of the purified water.

Water is most widely used for drinking purposes. The requirements standards in this case are determined by SanPiN 2.1.4.559-02. Drinking water. Hygienic requirements to water quality centralized systems drinking water supply. Quality control" . For example, some of them:

Tab. 1. Basic requirements for the ionic composition of water used for domestic and drinking water supply

For commercial consumers, water quality requirements are often stricter in some respects. For example, for the production of bottled water, a special standard has been developed with more stringent requirements for water - SanPiN 2.1.4.1116-02 “Drinking water. Hygienic requirements for the quality of water packaged in containers. Quality control". In particular, the requirements for the content of basic salts and harmful components - nitrates, organics, etc. have been tightened.

Water for technical and special purposes is water for use in industry or commercial purposes, for special technological processes - with special properties regulated by the relevant standards of the Russian Federation or the technological requirements of the Customer. For example, preparing water for energy (according to RD, PTE), for electroplating, preparing water for vodka, preparing water for beer, lemonade, medicine (pharmacopoeial monograph), etc.

Often, the requirements for the ionic composition of these waters are much higher than for drinking water. For example, for thermal power engineering, where water is used as a coolant and is heated, there are appropriate standards. For power plants there are so-called PTE (Technical Operation Rules), for general thermal power engineering the requirements are set by the so-called RD (Guide Document). For example, according to the requirements of the “Methodological guidelines for the supervision of the water chemical regime of steam and hot water boilers RD 10-165-97”, the value of the total water hardness for steam boilers with a working steam pressure of up to 5 MPa (50 kgf/cm2) should be no more 5 mcg-eq/kg. At the same time, the drinking standard SanPiN 2.1.4.559-02 requires that Jo be no higher than 7 mEq/kg.

Therefore, the task of chemical water treatment (CWT) for boiler houses, power plants and other facilities that require water treatment before heating water is to prevent the formation of scale and the subsequent development of corrosion on the inner surface of boilers, pipelines and heat exchangers. Such deposits can cause energy losses, and the development of corrosion can lead to a complete stop in the operation of boilers and heat exchangers due to the formation of deposits on the inside of the equipment.

It should be borne in mind that the technologies and equipment for water treatment and water treatment for power plants differ significantly from the corresponding equipment of conventional hot water boiler houses.

In turn, technologies and equipment for water treatment and chemical treatment for obtaining water for other purposes are also diverse and are dictated by both the parameters of the source water to be purified and the requirements for the quality of purified water.

SVT-Engineering LLC, having experience in this field, possessing qualified personnel and partnerships with many leading foreign and domestic specialists and firms, offers its clients, as a rule, those solutions that are appropriate and justified for each specific case, in in particular, based on the following basic technological processes:

The use of inhibitors and reagents for water treatment in various chemical treatment systems (both to protect membranes and thermal power equipment)

Most water treatment processes various types, including waste water, have been known and used for a relatively long time, constantly changing and improving. However, leading specialists and organizations around the world are working on the development of new technologies.

SVT-Engineering LLC also has experience in conducting R&D on behalf of clients in order to increase the efficiency of existing water purification methods, develop and improve new technological processes.

It should be especially noted that heavy use natural water sources in economic activity determines the need for environmental improvement of water use systems and technological processes of water treatment. Requirements for environmental protection require the maximum reduction of waste from water treatment plants into natural reservoirs, soil and atmosphere, which also necessitates the need to supplement technological schemes water treatment by stages of waste disposal, recycling and conversion into recyclable substances.

To date, enough has been developed big number methods that allow you to create low-waste water treatment systems. First of all, these include improved processes for preliminary purification of source water with reagents in clarifiers with lamellas and sludge recirculation, membrane technologies, demineralization based on evaporators and thermochemical reactors, corrective treatment of water with inhibitors of salt deposits and corrosion processes, technologies with countercurrent regeneration of ion exchange filters and more advanced ion exchange materials.

Each of these methods has its own advantages, disadvantages and limitations of their use in terms of the quality of source and purified water, the volume of wastewater and discharges, and parameters for the use of purified water. You can obtain additional information necessary to solve your problems and terms of cooperation by making a request or contacting our office.

This section describes in detail the existing traditional methods of water treatment, their advantages and disadvantages, and also presents modern new methods and new technologies for improving water quality in accordance with consumer requirements.

The main objectives of water treatment are to obtain clean, safe water suitable for various needs: household, drinking, technical and industrial water supply taking into account the economic feasibility of using the necessary methods of water purification and water treatment. The approach to water treatment cannot be the same everywhere. The differences are due to the composition of the water and the requirements for its quality, which vary significantly depending on the purpose of the water (drinking, technical, etc.). However, there is a set of typical procedures used in water treatment systems and the sequence in which these procedures are used.

Basic (traditional) methods of water treatment.

In water supply practice, in the process of purification and treatment, water is subjected to lightening(removal of suspended particles), discoloration ( removal of substances that give color to water) , disinfection(destruction of pathogenic bacteria in it). Moreover, depending on the quality of the source water, in some cases special methods of improving water quality are additionally used: softening water (reduction of hardness due to the presence of calcium and magnesium salts); phosphating(for deeper water softening); desalination, desalting water (reducing the overall mineralization of water); desiliconization, deferrization water (release of water from soluble iron compounds); degassing water (removal of soluble gases from water: hydrogen sulfide H 2 S, CO 2, O 2); deactivation water (removal of radioactive substances from water); neutralization water (removal of toxic substances from water), fluoridation(adding fluoride to water) or defluoridation(removal of fluorine compounds); acidification or alkalization ( to stabilize water). Sometimes it is necessary to eliminate tastes and odors, prevent the corrosive effect of water, etc. Certain combinations of these processes are used depending on the category of consumers and the quality of water in the sources.

The quality of water in a water body is determined by a number of indicators (physical, chemical and sanitary-bacteriological), in accordance with the purpose of the water and established quality standards. More about this in the next section. By comparing water quality data (obtained from analysis) with consumer requirements, measures for its treatment are determined.

The problem of water purification covers issues of physical, chemical and biological changes in the process of processing in order to make it suitable for drinking, i.e., cleaning and improving its natural properties.

The method of water treatment, the composition and design parameters of treatment facilities for technical water supply and the calculated doses of reagents are established depending on the degree of pollution of the water body, the purpose of the water supply system, the productivity of the station and local conditions, as well as on the basis of data from technological research and operation of structures operating in similar conditions .

Water purification is carried out in several stages. Debris and sand are removed at the pre-cleaning stage. A combination of primary and secondary treatment carried out at water treatment plants (WTPs) removes colloidal material (organic matter). Dissolved nutrients are eliminated using post-treatment. For treatment to be complete, water treatment plants must eliminate all categories of contaminants. There are many ways to do this.

With appropriate post-purification and high-quality WTP equipment, it is possible to ensure that the resulting water is suitable for drinking. Many people turn pale at the thought of recycling sewage, but it is worth remembering that in nature, in any case, all water circulates. In fact, appropriate post-treatment can provide water of better quality than that obtained from rivers and lakes, which often receive untreated sewage.

Basic methods of water treatment

Water clarification

Clarification is a stage of water purification, during which the turbidity of water is eliminated by reducing the content of suspended mechanical impurities in natural and waste water. The turbidity of natural water, especially surface sources during the flood period, can reach 2000-2500 mg/l (at the norm for drinking water - no more than 1500 mg/l).

Water clarification by sedimentation of suspended substances. This function is performed clarifiers, sedimentation tanks and filters, which are the most common water treatment plants. One of the most widely used practical methods for reducing the content of finely dispersed impurities in water is their coagulation(precipitation in the form of special complexes - coagulants) followed by sedimentation and filtration. After clarification, the water enters clean water tanks.

Discoloration of water, those. elimination or decolorization of various colored colloids or completely dissolved substances can be achieved by coagulation, the use of various oxidizing agents (chlorine and its derivatives, ozone, potassium permanganate) and sorbents (activated carbon, artificial resins).

Clarification by filtration with preliminary coagulation helps to significantly reduce bacterial contamination of water. However, among the microorganisms remaining in the water after water treatment there may also be pathogenic ones (bacillus of typhoid fever, tuberculosis and dysentery; cholera vibrio; polio and encephalitis viruses), which are a source of infectious diseases. For their final destruction, water intended for domestic purposes must be subjected to mandatory disinfection.

Disadvantages of coagulation, settling and filtration: costly and ineffective water treatment methods, which requires additional quality improvement methods.)

Water disinfection

Disinfection or disinfection is the final stage of the water treatment process. The goal is to suppress the vital activity of pathogenic microbes contained in the water. Since neither settling nor filtering provides complete release, chlorination and other methods described below are used to disinfect water.

In water treatment technology, a number of water disinfection methods are known, which can be classified into five main groups: thermal; sorption on active carbon; chemical(using strong oxidizing agents); oligodynamy(exposure to noble metal ions); physical(using ultrasound, radioactive radiation, ultraviolet rays). Of the listed methods, the methods of the third group are the most widely used. Chlorine, chlorine dioxide, ozone, iodine, and potassium permanganate are used as oxidizing agents; hydrogen peroxide, sodium and calcium hypochlorite. In turn, of the listed oxidizing agents, in practice preference is given to chlorine, bleach, sodium hypochloride. The choice of water disinfection method is made based on the flow rate and quality of the water being treated, the efficiency of its pre-treatment, the conditions of supply, transport and storage of reagents, the possibility of automating processes and mechanizing labor-intensive work.

Water that has undergone previous stages of treatment, coagulation, clarification and discoloration in a layer of suspended sediment or settling, filtering is subject to disinfection, since the filtrate does not contain particles on the surface or inside of which bacteria and viruses can be in an adsorbed state, remaining outside the influence of disinfecting agents.

Disinfection of water with strong oxidizing agents.

Currently, at housing and communal services facilities, water disinfection is usually chlorination water. If you drink tap water, you should know that it contains organochlorine compounds, the amount of which after the water disinfection procedure with chlorine reaches 300 μg/l. Moreover, this amount does not depend on the initial level of water pollution; these 300 substances are formed in water due to chlorination. Consumption of such drinking water can seriously affect your health. The fact is that when organic substances combine with chlorine, trihalomethanes are formed. These methane derivatives have a pronounced carcinogenic effect, which contributes to the formation cancer cells. When chlorinated water is boiled, it produces a powerful poison - dioxin. The content of trihalomethanes in water can be reduced by reducing the amount of chlorine used or replacing it with other disinfectants, for example, using granular activated carbon to remove organic compounds formed during water purification. And, of course, we need more detailed control over the quality of drinking water.

In cases of high turbidity and color of natural waters, preliminary chlorination of water is commonly used, but this method of disinfection, as described above, is not only not effective enough, but also simply harmful to our body.

Disadvantages of chlorination: is not effective enough and at the same time causes irreversible harm to health, since the formation of the carcinogen trihalomethanes promotes the formation of cancer cells, and dioxin leads to severe poisoning of the body.

It is not economically feasible to disinfect water without chlorine, since alternative methods of water disinfection (for example, disinfection with ultraviolet radiation) are quite expensive. An alternative method to chlorination was proposed for water disinfection using ozone.

Ozonation

A more modern procedure for water disinfection is water purification using ozone. Really, ozonation At first glance, water is safer than chlorination, but it also has its drawbacks. Ozone is very unstable and is quickly destroyed, so its bactericidal effect is short-lived. But the water must still pass through the plumbing system before ending up in our apartment. A lot of trouble awaits her along this path. It is no secret that water supply systems in Russian cities are extremely worn out.

In addition, ozone also reacts with many substances in water, such as phenol, and the resulting products are even more toxic than chlorophenols. Ozonation of water turns out to be extremely dangerous in cases where bromine ions are present in the water, even in the most insignificant quantities, difficult to determine even in laboratory conditions. Ozonation produces toxic bromine compounds - bromides, which are dangerous to humans even in microdoses.

The water ozonation method has proven itself very well for treating large masses of water - in swimming pools, in communal systems, i.e. where more thorough water disinfection is needed. But it must be remembered that ozone, as well as the products of its interaction with organochlorines, is toxic, therefore the presence of large concentrations of organochlorines at the water treatment stage can be extremely harmful and dangerous for the body.

Disadvantages of ozonation: The bactericidal effect is short-lived, and in reaction with phenol it is even more toxic than chlorophenols, which is more dangerous for the body than chlorination.

Disinfection of water with bactericidal rays.

CONCLUSIONS

All of the above methods are not effective enough, are not always safe, and, moreover, are not economically feasible: firstly, they are expensive and very costly, requiring constant maintenance and repair costs, secondly, they have a limited service life, and thirdly, they consume a lot of energy resources. .

New technologies and innovative methods for improving water quality

The introduction of new technologies and innovative methods of water treatment makes it possible to solve a set of problems that ensure:

production of drinking water that meets established standards and GOSTs and meets consumer requirements;
reliability of water purification and disinfection;
effective uninterrupted and reliable operation of water treatment facilities;
reducing the cost of water purification and water treatment;
saving reagents, electricity and water for your own needs;
quality of water production.

New technologies for improving water quality include:

Membrane methods based on modern technologies (including macrofiltration; microfiltration; ultrafiltration; nanofiltration; reverse osmosis). Used for desalination Wastewater, solve a complex of water purification problems, but purified water does not mean that it is healthy. Moreover, these methods are expensive and energy-intensive, requiring constant maintenance costs.

Reagent-free water treatment methods. Activation (structuring)liquids. Today there are many known ways to activate water (for example, magnetic and electromagnetic waves; ultrasonic frequency waves; cavitation; exposure to various minerals, resonance, etc.). The liquid structuring method provides a solution to a set of water treatment problems ( decolorization, softening, disinfection, degassing, deferrization of water etc.), while eliminating chemical water treatment.

Water quality indicators depend on the liquid structuring methods used and depend on the choice of technologies used, among which are:
- magnetic water treatment devices;
- electromagnetic methods;
- cavitation method of water treatment;
- resonant wave water activation (non-contact processing based on piezocrystals).

Hydromagnetic systems (HMS) designed for treating water in a flow with a constant magnetic field of a special spatial configuration (used to neutralize scale in heat exchange equipment; to clarify water, for example, after chlorination). The operating principle of the system is the magnetic interaction of metal ions present in water (magnetic resonance) and the simultaneous process of chemical crystallization. HMS is based on the cyclic effect on water supplied to heat exchangers by a magnetic field of a given configuration created by high-energy magnets. The magnetic water treatment method does not require any chemical reagents and is therefore environmentally friendly. But there are also disadvantages. HMS uses powerful permanent magnets based on rare earth elements. They retain their properties (magnetic field strength) for a very long time (tens of years). However, if they are overheated above 110 - 120 C, the magnetic properties may weaken. Therefore, HMS must be installed where the water temperature does not exceed these values. That is, before it heats up, on the return line.

Disadvantages of magnetic systems: the use of HMS is possible at temperatures no higher than 110 - 120°WITH; insufficiently effective method; For complete cleaning it is necessary to use it in combination with other methods, which ultimately is not economically feasible.

Cavitation method of water treatment. Cavitation is the formation of cavities in a liquid (cavitation bubbles or cavities) filled with gas, steam or a mixture thereof. The essence cavitation- another phase state of water. Under conditions of cavitation, water changes from its natural state to steam. Cavitation occurs as a result of a local decrease in pressure in the liquid, which can occur either with an increase in its speed (hydrodynamic cavitation) or with the passage of an acoustic wave during the rarefaction half-cycle (acoustic cavitation). In addition, the sharp (sudden) disappearance of cavitation bubbles leads to the formation of hydraulic shocks and, as a consequence, to the creation of a compression and tension wave in the liquid at an ultrasonic frequency. The method is used to remove iron, hardness salts and other elements exceeding the maximum permissible concentration, but is poorly effective in disinfecting water. At the same time, it consumes significant energy and is expensive to maintain with consumable filter elements (resource from 500 to 6000 m 3 of water).

Disadvantages: consumes electricity, is not efficient enough and is expensive to maintain.

CONCLUSIONS

The above methods are the most effective and environmentally friendly compared to traditional methods of water purification and water treatment. But they have certain disadvantages: the complexity of the installations, high cost, the need for consumables, difficulties in maintenance, significant areas are required to install water treatment systems; insufficient efficiency, and in addition restrictions on use (restrictions on temperature, hardness, pH of water, etc.).

Methods of non-contact activation of liquid (NL). Resonance technologies.

Liquid processing is carried out contactlessly. One of the advantages of these methods is the structuring (or activation) of liquid media, which provides all of the above tasks by activating the natural properties of water without consuming electricity.

The most effective technology in this area is NORMAQUA Technology ( resonant wave processing based on piezocrystals), contactless, environmentally friendly, no electricity consumption, non-magnetic, maintenance-free, service life - at least 25 years. The technology is based on piezoceramic activators of liquid and gaseous media, which are inverter resonators emitting ultra-low intensity waves. As with the influence of electromagnetic and ultrasonic waves, under the influence of resonant vibrations, unstable intermolecular bonds are broken, and water molecules are arranged in a natural physical and chemical structure in clusters.

The use of technology makes it possible to completely abandon chemical water treatment and expensive water treatment systems and consumables, and achieve the ideal balance between maintaining the highest water quality and saving equipment operating costs.

Reduce water acidity (increase pH level);
- save up to 30% of electricity on transfer pumps and erode previously formed scale deposits by reducing the friction coefficient of water (increasing the capillary suction time);
- change the redox potential of water Eh;
- reduce overall stiffness;
- improve the quality of water: its biological activity, safety (disinfection up to 100%) and organoleptic properties.

1. What is meant by the steam-water cycle of boiler plants

For reliable and safe operation of the boiler, the circulation of water in it is important - its continuous movement in the liquid mixture along a certain closed circuit. As a result, intensive heat removal from the heating surface is ensured and local stagnation of steam and gas is eliminated, which protects the heating surface from unacceptable overheating, corrosion and prevents boiler failure. Circulation in boilers can be natural or forced (artificial), created using pumps.

In Fig. A diagram of the so-called circulation circuit is shown. Water is poured into the vessel, and the left wheel of the U-shaped tube is heated, steam is formed; the specific gravity of the mixture of steam and water will be less compared to the specific gravity in the right elbow. The liquid in such conditions will not be in a state of equilibrium. For example, A - And the pressure on the left will be less than on the right - a movement begins, which is called circulation. Steam will be released from the evaporation mirror, further removed from the vessel, and feed water will flow into it in the same amount by weight.

To calculate circulation, two equations are solved. The first expresses the material balance, the second the balance of forces.

G under =G op kg/sec, (170)

Where G under is the amount of water and steam moving in the lifting part of the circuit, in kg/sec;

G op - the amount of water moving in the lower part, in kg/sec.

N = ∆ρ kg/m 2, (171)

where N is the total driving pressure equal to h(γ in - γ cm), in kg;

∆ρ – the sum of hydraulic resistance in kg/m2, including the force of inertia, arising when the steam-water emulsion and water move through the office and ultimately causing uniform movement at a certain speed.

Typically, the circulation ratio is selected in the range of 10 - 50 and, with a low heat load of the pipes, much more than 200 - 300.

M/sec,

2. Reasons for the formation of deposits in heat exchangers

Various impurities contained in heated and evaporated water can be released into the solid phase on the internal surfaces of steam generators, evaporators, steam converters and steam turbine condensers in the form of scale, and inside the water mass - in the form of suspended sludge. However, it is impossible to draw a clear boundary between scale and sludge, since substances deposited on the heating surface in the form of scale can turn into sludge over time, and vice versa; under certain conditions, sludge can stick to the heating surface, forming scale.

The radiation heating surfaces of modern steam generators are intensively heated by a combustion torch. The heat flow density in them reaches 600–700 kW/m2, and local heat flows can be even higher. Therefore, even a short-term deterioration in the heat transfer coefficient from the wall to boiling water leads to such a significant increase in the temperature of the pipe wall (500–600 °C and above) that the strength of the metal may not be sufficient to withstand the stresses that arise in it. The consequence of this is metal damage, characterized by the appearance of holes, lead, and often pipe rupture.

3. Describe the corrosion of steam boilers along the steam-water and gas paths

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1 . What is meant by the steam-water cycle of boiler mouths?anovok

The steam-water cycle is the period of time during which water turns into steam and this period is repeated many times.

IN modern designs In boilers, the heating surface is made of separate bundles of pipes connected to drums and collectors, which form a rather complex system of closed circulation circuits.

To calculate circulation, two equations are solved. The first expresses the material balance, the second the balance of forces.

The first equation is formulated as follows:

G under =G op kg/sec, (170)

Where G under is the amount of water and steam moving in the lifting part of the circuit, in kg/sec;

G op - the amount of water moving in the lower part, in kg/sec.

The balance of forces equation can be expressed by the following relationship:

N = ?? kg/m 2, (171)

where N is the total driving pressure equal to h(? in - ? cm), in kg;

The sum of hydraulic resistances in kg/m2, including the force of inertia, that arise when the steam-water emulsion and water move through the office and ultimately cause uniform movement at a certain speed.

In the circulation circuit of the boiler there is a large number of parallel working pipes, and their operating conditions cannot be completely identical for a number of reasons. In order to ensure uninterrupted circulation in all pipes of parallel operating circuits and not cause a circulation overturn in any of them, it is necessary to increase the speed of water movement along the circuit, which is ensured by a certain circulation ratio K.

Typically, the circulation ratio is selected in the range of 10 - 50 and, with a low heat load of the pipes, much more than 200 - 300.

The water flow in the circuit, taking into account the circulation rate, is equal to

where D = steam (feedwater) consumption of the calculated circuit in kg/hour.

The speed of water at the entrance to the lifting part of the circuit can be determined from the equality

2 . Reasons for the formation of sedimentdevelopments in heat exchangers

Of the elements of the steam generator, heated screen pipes are most susceptible to contamination of internal surfaces. The formation of deposits on the internal surfaces of steam-generating pipes entails a deterioration in heat transfer and, as a consequence, dangerous overheating of the pipe metal.

The radiation heating surfaces of modern steam generators are intensively heated by a combustion torch. The heat flow density in them reaches 600-700 kW/m2, and local heat flows can be even higher. Therefore, even a short-term deterioration in the heat transfer coefficient from the wall to boiling water leads to such a significant increase in the temperature of the pipe wall (500-600 ° C and above) that the strength of the metal may not be sufficient to withstand the stresses that arise in it. The consequence of this is metal damage, characterized by the appearance of holes, lead, and often pipe rupture.

During sharp temperature fluctuations in the walls of steam-generating pipes, which can occur during operation of the steam generator, scale peels off from the walls in the form of fragile and dense scales, which are carried by the flow of circulating water to places with slow circulation. There they settle in the form of a random accumulation of pieces of various sizes and shapes, cemented by sludge into more or less dense formations. If a drum-type steam generator has horizontal or slightly inclined sections of steam-generating pipes with sluggish circulation, then deposits of loose sludge usually accumulate in them. A narrowing of the cross-section for the passage of water or complete blockage of steam-generating pipes leads to circulation problems. In the so-called transition zone of a direct-flow steam generator, up to critical pressure, where the last remaining moisture evaporates and the steam is slightly overheated, deposits of calcium, magnesium compounds and corrosion products are formed.

Since a direct-flow steam generator is an effective trap for sparingly soluble compounds of calcium, magnesium, iron and copper. If their content in the feed water is high, they quickly accumulate in the pipe part, which significantly reduces the duration of the steam generator’s operating campaign.

In order to ensure minimal deposits both in the zones of maximum thermal loads of steam-generating pipes, as well as in the flow path of turbines, it is necessary to strictly maintain operational standards for the permissible content of certain impurities in the feed water. For this purpose, additional feed water is subjected to deep chemical purification or distillation in water treatment plants.

Improving the quality of condensates and feed water significantly weakens the process of formation of operational deposits on the surface of steam power equipment, but does not completely eliminate it. Therefore, in order to ensure proper cleanliness of the heating surface, it is necessary, along with one-time pre-start cleaning, to also carry out periodic operational cleaning of the main and auxiliary equipment, and not only in the presence of systematic gross violations of the established water regime and insufficient effectiveness of anti-corrosion measures carried out at thermal power plants, but also in conditions of normal operation of thermal power plants. Conducting operational cleaning is especially necessary at power units with direct-flow steam generators.

3 . Describe the corrosion of steam boiler houses according tosteam-water and gas paths

Metals and alloys used for the manufacture of thermal power equipment have the ability to interact with the environment in contact with them (water, steam, gases) containing certain corrosive impurities (oxygen, carbonic and other acids, alkalis, etc.).

Essential for disrupting the normal operation of a steam boiler is the interaction of substances dissolved in water with washing it with metal, resulting in destruction of the metal, which, at a certain size, leads to accidents and failure of individual elements of the boiler. Such destruction of metal environment called corrosion. Corrosion always starts from the surface of the metal and gradually spreads deeper.

Currently, there are two main groups of corrosion phenomena: chemical and electrochemical corrosion.

Chemical corrosion refers to the destruction of metal as a result of its direct chemical interaction with the environment. In the heat and power industry, examples of chemical corrosion are: oxidation of the outer heating surface by hot flue gases, corrosion of steel by overheated steam (so-called steam-water corrosion), corrosion of metal by lubricants, etc.

Electrochemical corrosion, as its name indicates, is associated not only with chemical processes, but also with the movement of electrons in interacting media, i.e. with the appearance of electric current. These processes occur when the metal interacts with electrolyte solutions, which takes place in a steam boiler in which boiler water circulates, which is a solution of salts and alkalis that have disintegrated into ions. Electrochemical corrosion also occurs when the metal comes into contact with air (at normal temperature), which always contains water vapor, which condenses on the surface of the metal in the form of a thin film of moisture, creating conditions for electrochemical corrosion to occur.

The destruction of a metal begins, essentially, with the dissolution of iron, which consists in the fact that the iron atoms lose some of their electrons, leaving them in the metal, and thus turn into positively charged iron ions that pass into the aqueous solution. This process does not occur uniformly over the entire surface of the metal washed with water. The fact is that chemically pure metals are usually not strong enough and therefore their alloys with other substances are used in technology. As is known, cast iron and steel are alloys of iron and carbon. In addition, silicon, manganese, chromium, nickel, etc. are added to the steel structure in small quantities to improve its quality.

Based on the form of manifestation of corrosion, they are distinguished: uniform corrosion, when the destruction of the metal occurs to approximately the same depth over the entire surface of the metal, and local corrosion. The latter has three main varieties: 1) pitting corrosion, in which corrosion of the metal develops in depth on a limited surface area, approaching pinpoint lesions, which is especially dangerous for boiler equipment (the formation of through fistulas as a result of such corrosion); 2) selective corrosion, when one of the constituent parts of the alloy is destroyed; for example, in turbine condenser tubes made of brass (an alloy of copper and zinc), when they are cooled with sea water, zinc is removed from the brass, as a result of which the brass becomes brittle; 3) intergranular corrosion, which occurs mainly in insufficiently tight rivet and rolling joints of steam boilers due to the aggressive properties of boiler water with simultaneous excessive mechanical stresses in these areas of the metal. This type of corrosion is characterized by the appearance of cracks along the boundaries of metal crystals, which makes the metal brittle.

4 . What water chemistry regimes are maintained in boilers and what do they depend on?

The normal operating mode of steam boilers is a mode that provides:

a) obtaining clean steam; b) absence of salt deposits (scaling) on the heating surfaces of boilers and sticking of the resulting sludge (so-called secondary scale); c) prevention of all types of corrosion of boiler metal and the steam-condenser tract carrying corrosion products into the boiler.

The listed requirements are satisfied by taking measures in two main directions:

a) when preparing source water; b) when regulating the quality of boiler water.

Preparation of source water, depending on its quality and requirements related to the design of the boiler, can be carried out by:

a) pre-boiler water treatment with removal of suspended and organic substances, iron, scale formers (Ca, Mg), free and bound carbon dioxide, oxygen, reduction of alkalinity and salt content (liming, hydrogen - cationization or desalting, etc.);

b) intra-boiler water treatment (with dosage of reagents or water treatment with a magnetic field with mandatory and reliable removal of sludge).

Regulation of the quality of boiler water is carried out by blowing boilers; a significant reduction in the size of the blowdown can be achieved by improving the boiler separation devices: staged evaporation, remote cyclones, steam flushing with feed water. The totality of the implementation of the listed measures that ensure the normal operation of boilers is called water - the chemical mode of operation of the boiler room.

The use of any method of water treatment: inside the boiler, before the boiler with subsequent corrective treatment of chemically purified or feed water - requires purging of steam boilers.

Under operating conditions of boilers, there are two methods of boiler purging: periodic and continuous.

Periodic purging from the lower points of the boiler is carried out to remove coarse sludge settling in the lower collectors (drums) of the boiler or circuits with sluggish water circulation. It is carried out according to a set schedule depending on the degree of contamination of the boiler water, but at least once per shift.

Continuous blowing of boilers ensures the necessary steam purity, maintaining a certain salt composition of the boiler water.

5 . Describe the structure of granularlightingx filters and the principle of their operation

Water clarification by filtration is widely used in water treatment technology; for this purpose, the clarified water is filtered through a layer of granular material (quartz sand, crushed anthracite, expanded clay, etc.) loaded into the filter.

Classification of filters according to a number of basic characteristics:

filtration speed:

Slow (0.1 - 0.3 m/h);

Ambulances (5 - 12 m/h);

Super high-speed (36 - 100 m/h);

the pressure under which they work:

Open or free-flowing;

Pressure;

number of filter layers:

Single layer;

Double layer;

Multilayer.

The most effective and economical are multilayer filters, in which, to increase dirt holding capacity and filtration efficiency, the load is made up of materials with different densities and particle sizes: on top of the layer there are large light particles, at the bottom there are small heavy ones. With downward filtration, large contaminants are retained in the upper loading layer, and the remaining small ones are retained in the lower layer. In this way, the entire loading volume works. Lighting filters are effective at retaining particles > 10 µm in size.

Water containing suspended particles, moving through a granular load that retains suspended particles, is clarified. The efficiency of the process depends on the physics - the chemical properties of the impurities, the filter load and hydrodynamic factors. Contaminants accumulate in the thickness of the load, the free pore volume decreases and the hydraulic resistance of the load increases, which leads to an increase in pressure losses in the load.

The removal of impurities from water and their fixation on the loading grains occurs under the influence of adhesion forces. The sediment formed on the loading particles has a fragile structure, which can collapse under the influence of hydrodynamic forces. Some of the previously adhered particles are torn off from the grains of the load in the form of small flakes and transferred to subsequent layers of the load (suffusion), where they are again retained in the pore channels. Thus, the process of water clarification should be considered as the total result of the process of adhesion and suffusion. Lightening in each elementary loading layer occurs as long as the intensity of particle adhesion exceeds the intensity of separation.

As the upper layers of the load become saturated, the filtration process moves to the lower ones, the filtration zone seems to move in the direction of flow from the area where the filter material is already saturated with contaminants and the process of suffusion predominates to the area of the fresh load. Then there comes a time when the entire filter loading layer is saturated with water contaminants and the required degree of water clarification is not achieved. The concentration of suspended matter at the loading outlet begins to increase.

The time during which water clarification to a given degree is achieved is called the time of the protective action of the load. When the maximum pressure loss is reached, the lighting filter must be switched to the loosening washing mode, when the load is washed with a reverse flow of water, and contaminants are discharged into the drain.

The possibility of retaining coarse suspended matter by a filter depends mainly on its mass; fine suspension and colloidal particles - from surface forces. The charge of suspended particles is important, since colloidal particles of the same charge cannot combine into conglomerates, enlarge and settle: the charge prevents their approach. This “alienation” of particles is overcome by artificial coagulation. As a rule, coagulation (sometimes, additionally, flocculation) is carried out in settling tanks - clarifiers. Often this process is combined with water softening by liming, or soda by liming, or caustic soda softening.

In conventional lighting filters, film filtration is most often observed. Volumetric filtration is organized in two-layer filters and in so-called contact clarifiers. The filter is filled with a lower layer of quartz sand with a size of 0.65 - 0.75 mm and an upper layer of anthracite with a grain size of 1.0 - 1.25 mm. A film does not form on the upper surface of the layer of large anthracite grains. Suspended substances that have passed through the anthracite layer are retained by the lower layer of sand.

When loosening the filter, the layers of sand and anthracite are not mixed, since the density of anthracite is half the density of quartz sand.

6 . Oplook for the softening process inodes using the cation exchange method

According to the theory of electrolytic dissociation, the molecules of some substances located in aqueous solution disintegrate into positively and negatively charged ions - cations and anions.

When such a solution passes through a filter containing a poorly soluble material (cation exchanger), capable of absorbing cations of the solution, including Ca and Mg, and instead releasing Na or H cations from its composition, water softening occurs. Water is almost completely freed from Ca and Mg, and its hardness is reduced to 0.1°

Na - kationation. With this method, calcium and magnesium salts dissolved in water, when filtered through a cation exchange material, Ca and Mg are exchanged for Na; As a result, only sodium salts with high solubility are obtained. The formula of the cation exchange material is conventionally designated by the letter R.

Cationite materials are: glauconite, sulfonated coal and synthetic resins. The most widely used coal at present is sulfonated coal, which is obtained after treating brown or bituminous coal with fuming sulfuric acid.

The capacity of a cation exchange material is the limit of its exchange capacity, after which, as a result of the consumption of Na cations, they must be restored by regeneration.

The capacity is measured in ton - degrees (t-deg) of scale formers, counting per 1 m 3 of cationic material. Ton - degrees are obtained by multiplying the consumption of purified water, expressed in tons, by the hardness of this water in degrees of hardness.

Regeneration is carried out with a 5 - 10% solution of table salt passed through a cation exchange material.

A characteristic feature of Na - cationization is the absence of salts that precipitate. The anions of hardness salts are sent entirely to the boiler. This circumstance necessitates increasing the amount of purge water. Water softening during Na - cationization is quite deep, the hardness of the feed water can be brought to 0° (practically 0.05-01°), while the alkalinity does not differ from the carbonate hardness of the source water.

The disadvantages of Na - cationization include the production of increased alkalinity in cases where there is a significant amount of temporary hardness salts in the source water.

It is possible to limit yourself to Na - cationization only if the carbonate hardness of the water does not exceed 3-6°. Otherwise, you have to significantly increase the amount of blowing water, which will create large heat losses. Typically, the amount of blowdown water does not exceed 5-10% of the total consumption used to feed the boiler.

The cationization method requires very simple maintenance and is accessible to ordinary boiler room personnel without the additional involvement of a chemist.

Cation filter design

N - Na-Toionization. If a cation exchange filter filled with sulfonic carbon is regenerated not with a solution of table salt, but with a solution of sulfuric acid, then an exchange will occur between the Ca and Mg cations found in the water being purified and the H cations of the sulfonic acid.

Water prepared in this way, also having negligible hardness, at the same time becomes acidic and thus unsuitable for feeding steam boilers, and the acidity of the water is equal to the non-carbonate hardness of the water.

By combining Na and H - cationite water softening together, you can get good results. The hardness of water prepared by the H-Na - cation exchange method does not exceed 0.1° with an alkalinity of 4-5°.

7 . Describe the principlebasic water treatment schemes

Implementation necessary changes in the composition of the treated water is possible according to various technological schemes, then the choice of one of them is made on the basis of comparative techniques - economic calculations for the planned variants of schemes.

As a result of chemical treatment of natural waters carried out at water treatment plants, the following main changes in their composition can occur: 1) water clarification; 2) water softening; 3) reducing water alkalinity; 4) reducing the salt content of water; 5) complete desalination of water; 6) degassing of water. Water treatment schemes required for implementation

the listed changes in its composition may include various processes, which are reduced to the following three main groups: 1) precipitation methods; 2) mechanical filtration of water; 3) ion exchange water filtration.

The use of technological schemes for water treatment plants usually involves a combination of various water treatment methods.

The figures show possible schemes of combined water treatment plants using these three categories of water treatment processes. These diagrams show only the main devices. Without auxiliary equipment, and the second and third stage filters are not indicated.

Scheme of water treatment plants

1-raw water; 2-illuminator; 3-mechanical filter; 4-intermediate tank; 5-pump; 6-coagulant dispenser; 7-Na - cation exchange filter; 8-N - cation exchange filter; 9 - decarbonizer; 10 - OH - anion filter; 11 - treated water.

Ion exchange filtration is a mandatory final stage of water treatment for all possible options schemes and is carried out in the form of Na - cationization, H-Na-cationization and H-OH - ionization of water. Clarifier 2 provides two main options for its use: 1) water clarification, when the processes of coagulation and sedimentation of water are carried out in it, and 2) water softening, when in addition to coagulation, liming is carried out in it, as well as, simultaneously with liming, magnesium desiliconization of water.

Depending on the characteristics of natural waters in terms of the content of suspended substances in them, three groups of technological schemes for their treatment are possible:

1) Underground artesian waters (indicated 1a in Fig.), which are practically usually free of suspended substances, do not require their clarification and therefore the treatment of such waters can be limited only to ion exchange filtration according to one of three schemes, depending on the requirements for the treated water: a ) Na - cationization, if only water softening is required; b) H-Na - cationization, if required, in addition to softening, a decrease in alkalinity or a decrease in the salt content of water; c) H-OH - ionization, if deep desalination of water is required.

2) surface waters with a low content of suspended solids (they are designated 1b in Fig.) can be processed using so-called direct-flow pressure schemes, in which coagulation and clarification in mechanical filters are combined with one of the ion-exchange filtration schemes.

3) surface waters with a relatively large amount of suspended substances (indicated 1c in Fig.) are cleared of them through clarification, after which they are subjected to mechanical filtration and then combined with one of the ion exchange filtration schemes. And often. In order to unload the ion-exchange part of the water treatment plant, simultaneously with coagulation, the water is partially softened in the clarifier and its salt content is reduced by liming and magnesium desiliconization. Such combined schemes are especially appropriate when treating highly mineralized waters, since even with their partial desalination by ion exchange, large amounts of water are required.

Solution:

Determine the filter inter-flushing period, h

where: h 0 - height of the filter layer, 1.2 m

Gr - dirt holding capacity of the filter material, 3.5 kg/m 3.

The value of Gr can vary widely depending on the nature of suspended substances, their fractional composition, filter material, etc. When calculating, you can take Gr = 3? 4 kg/m3, average 3.5 kg/m3,

U p - filtration speed, 4.1 m/h,

C in - concentration, suspended solids, 7 mg/l,

The number of filter washes per day is determined by the formula:

where: T 0 - inter-flushing period, 146.34 hours,

t 0 - filter downtime for washing, usually 0.3 - 0.5 hours,

Let's determine the required filtering area:

where: U-filtration speed, 4.1 m/h,

Q - Capacity, 15 m 3 / h,

In accordance with the rules and regulations for the design of water treatment plants, the number of filters must be at least three, then the area of one filter will be:

where: m - number of filters.

Based on the found area of one filter, we find the required filter diameter from the table: diameter d = 1500 mm, filtration area f = 1.72 m2.

Let's specify the number of filters:

If the number of filters is less than the inter-flushing period m 0? T 0 +t 0 (in our example 2

The filter calculation includes determining the water consumption for your own needs, i.e. for washing the filter and for washing the filter after washing.

Water consumption for filter washing and loosening is determined by the formula:

where: i- loosening intensity, l/(s * m 2); usually i = 12 l/(s * m2);

t - washing time, min. t = 15 min.

We determine the average water consumption for washing working filters using the formula:

Let us determine the flow rate for draining the first filter at a speed of 4 m/h for 10 minutes before putting it into operation:

Average water consumption for cleaning working filters:

Required amount of water for the filter unit, taking into account consumption for own needs:

Q p = g av + g av. elevation + Q

Q p = 0.9 + 0.018 + 15 = 15.9 m 3 / h

Literature

1. “Water treatment.” V.F. Vikhrev and M.S. Shkrob. Moscow 1973.

2. “Handbook for water treatment of boiler installations.” O.V. Lifshits. Moscow 1976

3. “Water treatment.” B.N. Frog, A.P. Levchenko. Moscow 1996.

4. “Water treatment.” CM. Gurvich. Moscow 1961.

Main stages of water treatment

Mechanical water purification. This is a preparatory stage of water treatment, aimed at removing large (visible) polluting particles from the water - sand, rust, plankton, silt and other heavy suspended matter. It is carried out before supplying water to the main treatment plants using screens with meshes of various diameters and rotating screens.
Chemical water purification. It is produced to bring water quality to standard levels. For this, various technological methods are used: clarification, coagulation, sedimentation, filtration, disinfection, demineralization, softening.

Lightening Required mainly for surface waters. It is carried out at the initial stage of drinking water purification in the reaction chamber and consists of adding a chlorine-containing preparation and a coagulant to the volume of water being treated. Chlorine contributes to the destruction of organic substances, mostly represented by humic and fulvic acids, inherent in surface waters and giving them a characteristic greenish-brown color.

Coagulation is aimed at purifying water from suspended matter and colloidal impurities that are invisible to the eye. Coagulants, which are aluminum salts, help the smallest suspended organic particles (plankton, microorganisms, large protein molecules) stick together and turn them into heavy flakes, which then precipitate. To enhance flocculation, flocculants can be added - chemicals of various brands.

Advocacy water loss occurs in tanks with a slow flow and overflow mechanism, where the lower layer of liquid moves slower than the upper layer. At the same time, the overall speed of water movement slows down, and conditions are created for the precipitation of heavy polluting particles.

Filtration on carbon filters or charcoalization, helps to get rid of 95% of impurities in water, both chemical and biological. Previously, water was filtered using cartridge filters with pressed activated carbons. But this method is quite labor-intensive and requires frequent and expensive regeneration of the filter material. At the present stage, the use of granular (GAC) or powdered (PAH) activated carbons, which are poured into water in a charcoal block and mixed with the treated water, is promising. Studies have shown that this method is much more effective than filtering through block filters, and is also less expensive. PAHs help eliminate contamination from chemical compounds, heavy metals, organics and, importantly, surfactants. Filtration using activated carbon is technologically available at any type of water supply plant.

Disinfection used on all types of water supply systems without exception to eliminate the epidemic danger of drinking water. Nowadays, disinfection methods provide a large selection of different methods and disinfectants, but one of the components is invariably chlorine, due to its ability to remain active in the distribution network and disinfect water pipes.

Demineralization on an industrial scale involves removing excess amounts of iron and manganese from water (deferrization and demanganization, respectively).

An increased iron content changes the organoleptic properties of water, causes it to turn yellow-brown, and gives an unpleasant “metallic” taste. Iron precipitates in pipes, creating conditions for their further contamination by biological agents, stains laundry during washing, and negatively affects plumbing equipment. In addition, high concentrations of iron and manganese can cause diseases of the gastrointestinal tract, kidneys and blood. An excess amount of iron is usually accompanied by a high content of manganese and hydrogen sulfide.

In public water supply systems, iron removal is carried out using the aeration method. In this case, divalent iron is oxidized to trivalent and precipitates in the form of rust flakes. This can then be eliminated using filters with different loads.

Aeration is carried out in two ways:

Pressure aeration - an air mixture is supplied to the contact chamber in the center through a pipe reaching half of the chamber. Then the water column is bubbling with bubbles of an air mixture, which oxidizes metal impurities and gases. The aeration column is not completely filled with water; there is an air cushion above the surface. Its task is to soften water hammer and increase the aeration area.
Non-pressure aeration - carried out using shower units. In special chambers, water is sprayed using water ejectors, which significantly increases the contact area of water with air.

In addition, iron is intensively oxidized when water is treated with chlorine and ozone.

Manganese is removed from water by filtering through modified loads or by adding oxidizing agents, for example, potassium permanganate.

Softening water is carried out to eliminate hardness salts - calcium and magnesium carbonates. For this purpose, filters loaded with acidic or alkaline cation exchangers or anion exchangers are used, replacing calcium and magnesium ions with neutral sodium. This is a rather expensive method, therefore it is most often used at local water treatment plants.

Supplying water to the distribution network.

After passing through a full complex of treatment facilities at the water supply station, the water becomes potable. Then it is supplied to the consumer by a system of water pipes, the condition of which in most cases leaves much to be desired. Therefore, more and more often the question is raised about the need for additional purification of tap drinking water and not only bringing it to regulatory requirements, but also imparting qualities beneficial to health.

In the conditions of a modern big city, with polluted air and a rather poor environment, every person strives to maintain health. Water is the main product for each of us. Recently, more and more people are thinking about what kind of water they use. In this regard, water hardness and water purification are not empty terms, but important parameters. Today, specialists successfully use water treatment and water purification technologies, which helps obtain much cleaner water suitable for consumption. Professionals also pay attention to water softening, carrying out a number of measures to improve its properties.

What do water treatment technologies provide?

Let's take a closer look at what water treatment technologies are. This is primarily the purification of water from plankton. This microorganism, which lives in rivers, began to develop most intensively after large reservoirs appeared. Note that when plankton develops in large quantities, the water begins to smell unpleasant, change color and acquire a characteristic taste.

Today, many industrial companies pour their untreated wastewater into rivers with a huge content of organic pollutants and chemical impurities. Drinking water is subsequently obtained from these open reservoirs. As a result, most of them, mainly those located in or near megacities, are very polluted. The water contains phenols, organochlorine pesticides, ammonium and nitrite nitrogen, petroleum products and other harmful substances. Of course, water from such sources is unsuitable for consumption without prior preparation.

We should not forget about new production technologies, various emergencies and accidents. All these factors can also worsen the condition of water in sources and negatively affect its quality. Thanks to modern research methods, scientists were able to find oil products, amines, phenols, and manganese in water.

Water treatment technologies, when it comes to a city, include the construction of water treatment plants. By passing through several stages of purification, water becomes more suitable for drinking. But nevertheless, even with the use of water treatment facilities, it is not completely freed from harmful impurities, and therefore it enters our homes still quite contaminated.

Today, there are various technologies for water treatment and purification of drinking and waste water. As part of these measures, mechanical purification is used to remove various impurities using installed filters, remove residual chlorine and chlorine-containing elements, purify water from a large amount of mineral salts contained in it, and also soften and remove salts and iron.

Basic water treatment and water purification technologies

Technology 1. Lightening

Clarification is the stage of water purification at which its turbidity is eliminated, reducing the amount of mechanical impurities in natural and waste waters. The level of turbidity in water, especially in surface sources during floods, sometimes reaches 2000–2500 mg/l, while the norm for water suitable for drinking and household use is no more than 1500 mg/l.

Water is clarified by precipitating suspended substances using special clarifiers, settling tanks and filters, which are the most well-known water treatment facilities. One of the most well-known methods widely used in practice is coagulation, that is, reducing the amount of finely dispersed impurities in water. As part of this water treatment technology, coagulants are used - complexes for sedimentation and filtering of suspended substances. Next, the clarified liquid enters clean water tanks.

Technology 2. Discoloration

Coagulation, the use of various oxidizing agents (for example, chlorine along with its derivatives, ozone, manganese) and sorbents (active carbon, artificial resins) make it possible to decolorize water, that is, eliminate or discolor colored colloids or completely dissolved substances in it.

Thanks to this water treatment technology, water contamination can be significantly reduced by eliminating most bacteria. Moreover, even after removing some harmful substances, others often remain in the water, for example, bacilli of tuberculosis, typhoid fever, dysentery, Vibrio cholera, encephalitis and polio viruses that cause infectious diseases. In order to completely destroy them, water used for domestic and economic needs must be disinfected.

Coagulation, sedimentation and filtration have their disadvantages. These water treatment technologies are insufficiently efficient and expensive, and therefore it is necessary to use other methods of purification and improvement of water quality.

Technology 3. Desalting

With this water treatment technology, all anions and cations that affect the salt content in general and the level of its electrical conductivity are removed from water. When desalting, reverse osmosis, ion exchange and electrodeionization are used. Depending on the level of salt content and what requirements exist for demineralized water, the appropriate method is chosen.

Technology 4. Disinfection

The final stage of water purification is disinfection, or disinfection. The main task of this water treatment technology is to suppress the activity of harmful bacteria in the water. To completely purify water from microbes, filtration and sedimentation are not used. To disinfect it, it is chlorinated, and other water treatment technologies are used, which we will discuss later.

Today, experts use many methods of water disinfection. Water treatment technologies can be divided into five main groups. The first method is thermal. The second is sorption on active carbon. The third is chemical, in which strong oxidizing agents are used. The fourth is oligodynamy, in which ions act on noble metals. The fifth is physical. This water treatment technology uses radioactive radiation, ultraviolet rays and ultrasound.

As a rule, when disinfecting water, chemical methods are used using ozone, chlorine, chlorine dioxide, potassium permanganate, hydrogen peroxide, sodium hypochlorite and calcium as oxidizing agents. As for a specific oxidizing agent, in this case chlorine, sodium hypochloride, and bleach are most often used. The disinfection method is chosen based on the consumption and quality of the water being treated, the effectiveness of its initial purification, the conditions for transportation and storage of reagents, the ability to automate processes and mechanize complex work.

Specialists disinfect water that has been pre-treated, coagulated, clarified and discolored in a layer of suspended sediment, or settled, filtered, since the filter does not contain particles on or inside which adsorbed microbes may be located that have not been disinfected.

Technology 5.Disinfection using strong oxidizing agents

At the moment, in the housing and communal services sector, water is usually chlorinated in order to purify and disinfect it. When drinking tap water, you should be aware of the content of organochlorine compounds, the level of which after disinfection using chlorine is up to 300 μg/l. At the same time, the initial threshold of contamination does not affect this indicator, since it is chlorination that causes the formation of these 300 microelements. It is highly undesirable to consume water with such indicators. Chlorine, combining with organic substances, forms trihalomethanes - methane derivatives, which have a pronounced carcinogenic effect, as a result of which cancer cells appear.

When chlorinated water is boiled, it produces a highly toxic substance called dioxin. You can reduce the level of trihalomenates in water by reducing the amount of chlorine used during disinfection and replacing it with other disinfection substances. In some cases, granular activated carbon is used to remove organic compounds formed during disinfection. Of course, we should not forget about complete and regular monitoring of drinking water quality indicators.

If natural waters are very cloudy and have a high color, they often resort to preliminary chlorination. But, as mentioned earlier, this water treatment technology does not have sufficient efficiency, and it is also very harmful to our health.

The disadvantages of chlorination as a water treatment technology, therefore, include low efficiency plus enormous damage to the body. When the carcinogen trihalomethane is formed, cancer cells appear. Regarding dioxin formation, this element, as noted above, is a powerful poison.

Without the use of chlorine, water disinfection is not feasible from an economic point of view. Various alternative water treatment technologies (for example, disinfection using UV radiation) are quite expensive. The best option today is water disinfection using ozone.

Technology 6.Ozonation

Disinfection using ozone seems safer than chlorination. But this water treatment technology also has its disadvantages. Ozone does not have increased resistance and is prone to rapid destruction, and therefore has a bactericidal effect for a very short time. This requires water to pass through the plumbing system before entering our homes. This is where difficulties arise, since we all have an idea of the approximate degree of deterioration of water pipelines.

Another nuance of this water treatment technology is that ozone reacts with many substances, including, for example, phenol. The elements formed during their interaction are even more toxic. Disinfecting water using ozone is a dangerous undertaking if the water contains a tiny percentage of bromine ions (it is difficult to detect even in the laboratory). When ozonation is performed, toxic bromine compounds appear - bromides, which pose a danger to humans even in microdoses.

In this case, ozonation is the best option for disinfecting large volumes of water, requiring thorough disinfection. But do not forget that ozone, like the substances that appear during its reactions with organochlorines, is a toxic element. In this regard, a high concentration of organochlorines at the stage of water purification may represent great harm and health hazard.

So, the disadvantages of disinfection using ozone include even greater toxicity when interacting with phenol, which is even more dangerous than chlorination, as well as a short bactericidal effect.

Technology 7.Disinfection using bactericidal rays

To disinfect groundwater, bactericidal rays are often used. They can be used only if the coli index of the initial state of the water is not higher than 1000 units/l, the iron content is up to 0.3 mg/l, and the turbidity is up to 2 mg/l. Compared to disinfection with chlorine, the bactericidal effect on water is optimal. In the taste of water and its chemical properties When using this water treatment technology, no changes occur. The rays penetrate the water almost instantly, and after their exposure it becomes suitable for consumption. Using this method, not only vegetative but also spore-forming bacteria are destroyed. In addition, using installations for water disinfection in this way is much more convenient than using chlorination.

In the case of untreated, turbid, colored or waters in which the level of iron content is high, the absorption coefficient turns out to be so strong that the use of bactericidal rays becomes unjustified from an economic point of view and not sufficiently reliable from a sanitary point of view. In this regard, the bactericidal method is better used to disinfect already purified water or to disinfect groundwater that does not require purification, but requires disinfection for prevention.

The disadvantages of disinfection using bactericidal rays include the economic unjustification and unreliability of this water treatment technology from a sanitation point of view.

Technology 8.Deferrization

The main sources of iron compounds in natural water are weathering processes, soil erosion and dissolution rocks. As for drinking water, iron may be present in it due to corrosion of water supply pipes, and also because municipal treatment plants used iron-containing coagulants to clarify the water.

Exists modern direction in non-chemical methods of groundwater purification. This is a biological method. This water treatment technology is based on the use of microorganisms, most often iron bacteria, which convert Fe 2 + (ferrous iron) into Fe 3 + (rust). These elements are not hazardous to human health, but their waste products are quite toxic.

The basis of modern biotechnologies is the use of the properties of a catalytic film, which is formed on a load of sand and gravel or other similar material with small pores, as well as the ability of iron bacteria to ensure the occurrence of complex chemical reactions without energy costs and reagents. These processes are natural, and they are based on biological natural laws. Iron bacteria actively and in large numbers develop in water, the iron content of which is from 10 to 30 mg/l, but practice shows that they can live at a lower concentration (100 times). The only condition here is sufficient support low level acidity of the environment and simultaneous access of oxygen from the air, at least in a small volume.

The final stage of using this water treatment technology is sorption purification. It is used to retain bacterial waste products and carry out final disinfection of water using bactericidal rays.

This method has quite a few advantages, the most important of which is, for example, environmental friendliness. He has every chance for further development. However, this water treatment technology also has a disadvantage - the process takes a lot of time. This means that in order to ensure large production volumes, tank structures must be large-sized.

Technology 9. Dgassing

The corrosive aggressiveness of water is influenced by certain physical and chemical factors. In particular, water becomes aggressive if it contains dissolved gases. As for the most common and corrosive elements, carbon dioxide and oxygen can be noted here. It is no secret that if the water contains free carbon dioxide, oxygen corrosion of the metal becomes three times more intense. In this regard, water treatment technologies always involve the removal of dissolved gases from water.

There are main ways to remove dissolved gases. Within their framework, physical desorption is used, and they also use chemical methods of binding them to remove residual gas. The use of such water treatment technologies, as a rule, requires high energy costs, large production areas, and consumption of reagents. In addition, all this can cause secondary microbiological contamination of water.

All of the above circumstances contributed to the emergence of a fundamentally new water treatment technology. This is membrane degassing, or degasification. Using this method, specialists, using a special porous membrane into which gases can penetrate, but water cannot penetrate, remove gases dissolved in water.

The basis of the action of membrane degassing is the use of special large-area membranes (usually created on the basis of hollow fiber) placed in pressure housings. Gas exchange processes occur in their micropores. Membrane water treatment technology makes it possible to use more compact installations, and the risks that water will again be subject to biological and mechanical contamination are minimized.

Thanks to membrane degassers (or MDs), it is possible to remove dissolved gases from water without dispersing it. The process itself is carried out in water, then in a membrane, then in a gas flow. Despite the presence of an ultraporous membrane in MD, the operating principle of a membrane degasser differs from other types of membranes (reverse osmosis, ultrafiltration). In the space of the degasser membranes, there is no flow of liquid through the membrane pores. The membrane is an inert gas-tight wall that serves as a separator for the liquid and gaseous phases.

Expert opinion

Features of the application of groundwater ozonation technology

V.V. Dzyubo,

L.I. Alferova,

Senior Researcher, Department of Water Supply and Sanitation, Tomsk State University of Architecture and Civil Engineering

How effective ozonation will be as a technology for water treatment and purification of groundwater is influenced not only by the parameters of ozone synthesis: electrical energy costs, price, etc. It is also important how effectively the mixing and dissolution of ozone occurs in the water undergoing treatment. We should not forget about the quality composition.

Cold water is more suitable for better dissolution of ozone, and the substance disintegrates faster when the temperature aquatic environment growing. As saturation pressure increases, ozone also dissolves better. All this needs to be taken into account. For example, ozone dissolves up to 10 times faster in a certain temperature environment than oxygen.

Research related to water ozonation has been repeatedly conducted in Russia and abroad. The results of studies of this water treatment technology showed that the level of water saturation with ozone (the maximum possible concentration) is influenced by the following factors:

the ratio of the volume of the supplied mixture of ozone and air (m 3) and the amount of treated water Qw (m 3) - (Qoz / Qw);
ozone concentration in the mixture of ozone and air that is supplied to the water;
volume of water being treated;
temperature of the water being treated;
saturation pressure;
duration of saturation.

If the source of water supply is groundwater, it should be remembered that it may change depending on the season, in particular its quality becomes different. This must be taken into account when justifying water treatment technologies for organizing public water supply, especially if it uses ozonation.

If ozone is used in groundwater water treatment technologies, one should not forget about significant differences in their quality in different regions of Russia. In addition, the quality of groundwater differs from the composition of previously studied clean water. In this regard, the use of any known water treatment technology or technological parameters for water treatment will be incorrect, since the qualitative composition and specifics of the water to be treated should always be taken into account. For example, there will always be differences between the real or actually achieved ozone concentration in natural groundwater subject to treatment and the theoretically possible or achieved values using clean water. When justifying certain water treatment technologies, a detailed study of the qualitative composition of the water source is required first of all.

Wastewater treatment and disinfection: modern issues

Modern water treatment technologies and innovative methods

By introducing new methods and technologies of water treatment, it is possible to solve certain problems, the achievement of which ensures:

production of drinking water in accordance with GOST and current standards that meet the requirements of customers;
reliable water purification and disinfection;
uninterrupted and reliable operation of water treatment facilities;
reducing the cost of water preparation and purification processes;
saving reagents, electrical energy and water for personal needs;
high quality water production.

The latest water treatment technologies that are used to improve water should also be touched upon.

1. Membrane methods

Membrane methods are based on modern water treatment technologies, which include macro- and micro-, ultra- and nanofiltration, as well as reverse osmosis. Membrane water treatment technology is used to desalinate wastewater and solve problems associated with water treatment. At the same time, purified water cannot yet be called useful and safe for the body. Note that membrane methods are expensive and energy-intensive, and their use is associated with constant maintenance costs.

2. Reagent-free methods

Here we should first of all highlight the structuring, or activation, of the liquid as the most frequently used method. Today, there are various methods of activating water (for example, the use of magnetic and electromagnetic waves, cavitation, ultrasonic frequency waves, exposure to various minerals, resonance methods). Using structuring, you can solve a number of problems in water preparation (bleach, soften, disinfect, degas, deferrize water and carry out a number of other manipulations). Chemical water treatment technologies are not used.

Activated water and liquid to which traditional water treatment technologies have been applied are different from each other. The disadvantages of traditional methods have already been mentioned earlier. The structure of activated water is similar to the structure of water from a spring, “living” water. It has many healing properties and great benefit for the human body.

To remove turbidity (thin suspensions that are difficult to settle) from a liquid, another method of activated water is used - its ability to accelerate the coagulation (adhesion and sedimentation) of particles and the subsequent formation of large flakes. Chemical processes and crystallization of dissolved substances occur much faster, absorption becomes more intense, and there is an improvement in the coagulation of impurities and their precipitation. In addition, such methods are often used to prevent the formation of scale in heat exchange equipment.

Water quality is directly affected by the activation methods and water treatment technologies used. Among them:

magnetic water treatment devices;
electromagnetic methods;
cavitation;
resonant wave structuring of liquid (this water treatment technology is non-contact, and is based on piezocrystals).

3. Hydromagnetic systems

The purpose of HMS (hydromagnetic systems) is to process water flows using a constant magnetic field of a special spatial configuration. HMS is used to neutralize scale in heat exchange equipment, as well as to clarify water (for example, after disinfection with chlorine). This system works like this: metal ions in water interact with each other at a magnetic level. At the same time, chemical crystallization occurs.

Treatment using hydromagnetic systems does not require chemical reagents, and therefore this cleaning method is environmentally friendly. But there are also disadvantages to GMS. As part of this water treatment technology, permanent powerful magnets are used, which are based on rare earth elements that retain their parameters (magnetic field strength) for a long time (decades). But if these elements are overheated above 110–120 o C, the magnetic properties may weaken. In this regard, the installation of hydromagnetic systems should be carried out in places where the water temperature does not exceed these values, i.e. before it is heated (return line).

So, the disadvantages of HMS include the possibility of use at a temperature of no more than 110–120 o C, insufficient efficiency, and the need to use other methods together with it, which is unprofitable from an economic point of view.

4. Cavitation method

During cavitation, cavities (cavities or cavitation bubbles) are formed in water, inside which there is gas, steam or a mixture of them. During cavitation, water passes into another phase, that is, it turns from liquid to vapor. Cavitation appears when the pressure in the water decreases. A change in pressure is caused by an increase in its speed (with hydrodynamic cavitation), the passage of acoustic water during the rarefaction half-period (with acoustic cavitation).

When cavitation bubbles suddenly disappear, water hammer occurs. As a result, a compression and tension wave is created in water at ultrasonic frequency. The cavitation method is used to purify water from iron, hard salts and other substances that exceed the maximum permissible concentration. At the same time, water disinfection by cavitation is not very effective. Other disadvantages of using the method include significant energy consumption and expensive maintenance with consumable filter elements (resource from 500 to 6000 m 3 of water).

Technologies for water treatment of drinking water for housing and communal services according to the scheme

Scheme 1.Aeration - degassing - filtration - disinfection

This water treatment technology can be called the simplest from a technological point of view and constructive in implementation. The scheme is implemented using different methods of aeration and degassing - it all depends on the qualitative composition of the groundwater. Here are two key uses of this water treatment technology:

aeration-degassation of liquid in the initial state in the tank; forced air supply and subsequent filtration using granular filters and disinfection by UV irradiation are not used. During aeration-degassing, spraying is carried out onto a hard contact layer using ejector nozzles and vortex nozzles. A contact pool, a water tower, etc. can act as a reservoir of initial water. The filters here are albitophyres and burnt rocks. This technology is usually used to purify groundwater that contains mineral forms of dissolved Fe 2 + and Mn 2 + that do not contain H 2 S, CH 4 and anthropogenic pollutants;
aeration-degassing, carried out in a similar way to the previous method, but with the additional use of forced air supply. This method is used if the groundwater contains dissolved gases.

Purified water can be supplied to special RWCs (clean water reservoirs) or towers, which are special storage tanks, provided that they have not already been used as a receiving tank. The water is then transported to consumers via distribution networks.

Scheme 2.Aeration-degassing - filtration - ozonation - filtration at GAC - disinfection

As for this water treatment technology, its use is advisable for complex purification of groundwater if there are strong contaminants in high concentrations: Fe, Mn, organic matter, ammonia. During this method, single or double ozonation is carried out:

if there are dissolved gases CH 4, CO 2, H 2 S, organic matter and anthropogenic pollution in the water, ozonation is carried out after aeration-degassing with filtration using inert materials;
if there is no CH 4, at (Fe 2 +/Mn 2 +)< 3: 1 озонирование нужно проводить на первом этапе аэрации-дегазации. Уровень доз озона в воде не должен быть выше 1,5 мг/л, чтобы не допустить окисления Mn 2 + до Mn 7 +.

You can use the filter materials indicated in diagram A. If sorption purification is used, activated carbon and clinoptilolite are often used.

Scheme 3. Aeration-degassing - filtration - deep aeration in vortex aerators with ozonation - filtration - disinfection

This technology develops the technology for purifying groundwater according to scheme B. It can be used to purify waters that contain elevated levels of Fe (up to 20 mg/l) and Mn (up to 3 mg/l), petroleum products up to 5 mg/l, phenols up to 3 µg/l and organics up to 5 mg/l with the pH of the source water close to neutral.

Within this water treatment technology, it is best to use UV irradiation to disinfect purified water. Territories for bactericidal installations can be:

places located directly before the supply of purified water to consumers (if the length of the networks is short);
right in front of the water points.

Taking into account the quality of groundwater from a sanitary point of view and the state of the water supply system (networks, structures on them, RHF, etc.), equipping stations or water treatment equipment for the purpose of disinfecting water before supplying it to consumers may imply the presence any equipment acceptable for the conditions of a particular territory.

Scheme 4.Intensive degassing-aeration - filtration (AB; GP) - disinfection (Ural irradiation)

This water treatment technology includes stages of intensive degassing-aeration and filtration (sometimes two-stage). The use of this method is advisable when it is necessary to remove dissolved CH 4, H 2 S and CO 2, which are present in high concentrations with a fairly low content of dissolved forms of Fe and Mn - up to 5 and 0.3 mg/l, respectively.

As part of the application of water treatment technology, enhanced aeration and filtration are performed in 1–2 stages.

To perform aeration, they use vortex nozzles (in relation to individual systems), vortex degassers - aerators, combined degassing and aeration units (columns) with simultaneous removal of gases.

As for filter materials, they are similar to those indicated in scheme A. When the groundwater contains phenols and petroleum products, filtration is carried out using sorbents - activated carbons.

In accordance with this scheme, water is filtered using two-stage filters:

1st stage - to purify water from Fe and Mn compounds;
2nd stage - to carry out sorption purification of water, which has already been purified, from petroleum products and phenols.

If possible, only the first stage of filtering is performed, due to which the circuit becomes more flexible. At the same time, the implementation of such water treatment technology requires more costs.

If we consider small and medium settlements, the use of this water treatment technology is preferable in the pressure version.

As part of the application of water treatment technology, you can use any method of disinfection of water that has already been purified. It all depends on how productive the water supply system is and what are the conditions of the territory where the water treatment technology is used.

Scheme 5.Ozonation - filtration - filtration - disinfection (NaClO)

If it is necessary to remove anthropogenic and natural contaminants, they resort to ozonation with further filtration through a granular load and adsorption on GAC and disinfection with sodium hypochlorite when the total iron content in the water is up to 12 mg/l, potassium permanganate is up to 1.4 mg/l and oxidability is up to 14 mg O 2 /l.

Scheme 6.Aeration-degassing - coagulation - filtration - ozonation - filtration - disinfection (NaClO)

This option is similar to the previous scheme, but here aeration-degassing is used and a coagulant is introduced before the deferrization and demanganization filters. Thanks to water treatment technology, it is possible to remove anthropogenic pollutants in a more complex situation, when the level of iron reaches up to 20 mg/l, manganese up to 4 mg/l and there is high permanganate oxidation - 21 mg O 2 /l.

Scheme 7.Aeration-degassing - filtration - filtration - ion exchange - disinfection (NaClO)

This scheme is recommended for areas of Western Siberia where there are significant oil and gas deposits. As part of the water treatment technology, water is freed from iron, sorbtion is carried out on GAC, ion exchange is carried out on clinoptilolite in Na-form with further disinfection and sodium hypochlorite. Let us note that the scheme is already being successfully used in Western Siberia. Thanks to this water treatment technology, the water complies with all SanPiN 2.1.4.1074–01 standards.

Water treatment technology also has disadvantages: periodically, ion exchange filters must be regenerated using a solution of table salt. Accordingly, the issue of destruction or secondary use of the regeneration solution arises here.

Scheme 8. Aeration-degassation - filtration (C + KMnO 4) - ozonation - sedimentation - adsorption (C) - filtration (C + KMnO 4) (demanganation) - adsorption (C) - disinfection (Cl)

Thanks to the water treatment technology according to this scheme, heavy metals, ammonium, radionuclides, anthropogenic organic pollutants, etc., as well as manganese and iron are removed from the water in two stages - using coagulation and filtration through a charge of natural zeolite (clinoptilolite), ozonation and sorption on the zeolite . Regenerate the load using the reagent method.

Scheme 9. Aeration-degassation - ozonation - filtration (clarification, deferrization, demanganation) - adsorption on GAC - disinfection (Ural irradiation)

Within the framework of this water treatment technology, the following activities are carried out:

Methane is completely removed with a concomitant increase in pH as a result of partial stripping of carbon dioxide, hydrogen sulfide, as well as volatile organochlorine compounds (VOC), preozonation, oxidation of preozonation and hydrolysis of iron are performed (deep aeration-degassation stage);
2-3-valent iron and iron phosphate complexes, partially manganese and heavy metals are removed (filtration stage of water treatment technology);
destroy residual persistent complexes of iron, potassium permanganate, hydrogen sulfide, anthropogenic and natural organic substances, sorption of ozonation products, nitrify ammonium nitrogen (ozonation and sorption stage).

Purified water must be disinfected. To do this, UV irradiation is performed, a small dose of chlorine is introduced, and only then the liquid is supplied to the water distribution networks.

Expert opinion

How to choose the right water treatment technology

V.V. Dzyubo,

Dr. Tech. Sciences, Professor of the Department of Water Supply and Sanitation, Tomsk State University of Architecture and Civil Engineering

From an engineering point of view, it is quite difficult to design water treatment technologies and draw up technological schemes according to which it is necessary to bring water to drinking standards. The determination of the method of processing groundwater as a separate stage in the development of a general water treatment technology is influenced by the qualitative composition of natural waters and the required depth of purification.

Groundwater in Russian regions is different. It is on their composition that water treatment technologies and achieving water compliance with drinking standards depend on SanPiN 2.1.4.1074–01 “Drinking water. Hygienic requirements for water quality of centralized drinking water supply systems. Quality control. Sanitary and epidemiological rules and regulations.” The water treatment technologies used, their complexity and, of course, the cost of purification equipment also depend on the initial quality and content of drinking water.

As already noted, the composition of waters is different. Its formation is influenced by the geographic, climatic, and geological conditions of the area. For example, the results of natural studies of the composition of waters in different territories of Siberia indicate that they have different characteristics in different seasons, since their nutrition changes depending on the time of year.

When the conditions for the extraction of groundwater from aquifers are violated, water flows from neighboring horizons, which also affects the change in characteristics and qualitative composition of liquids.

Since the choice of one or another water treatment technology depends on the characteristics of water, it is necessary to analyze their composition in detail and completely in order to choose the least expensive and most effective option.

The KF Center company has been operating in the market of water purification and water treatment systems since 1997. We present to our customers high quality equipment. Specializing not only in the field of sales, but also in developments in this industry, the company has the opportunity to present in its catalog not only the most modern, but also the most diverse technological complexes for water purification. But first things first.

Water purification and water treatment: importance in the modern world

Today it is no secret to anyone that the quality of our life largely depends on the quality of water. This issue is especially acute in megacities, where the amount of clean water consumed by the population is striking in its scale. Also, water treatment and water purification are important for various industries. Be it industrial complexes or agricultural enterprises.

Understanding the current market demands, the KF Center company strives to meet the most modern requirements for the supply of professional water treatment and water purification systems. Therefore, when turning to the company’s specialists, you can always be sure that they will find a solution to any problem you face.

Water treatment plants - innovations or traditional technologies?

Today, a modern water treatment or water purification system is a combination of traditional technologies and industry innovations. Based on the discoveries of previous generations and wanting to keep up with the times, the KF Center company offers its customers the most efficient modern equipment.

Water treatment and water purification plants in the assortment of the KF Center company

The KF Center company presents on the market various technological complexes capable of solving both a wide range of problems and highly specialized requests. After all, it’s no secret that the selection of equipment for water treatment or water purification depends on the quality of the source water, as well as on the Customer’s requirements for the quality of the treated water.

Thus, water for the housing and communal services sector must meet a number of factors in order to be suitable for household use. U Food Industry its requirements for water, which are very stringent in terms of the purity of the final product. What can we say about industrial use, where a strictly defined chemical composition of water may be required.
Responding to numerous requests from its customers, the KF Center company is constantly expanding its product line, offering the market a wide variety of water treatment and water purification systems. Among them:

filters for softening water and removing dissolved iron;
filters for removing mechanical impurities;
cartridge type filters;
hydrocyclone type filters;
ultraviolet sterilizers;
proportional dosing complexes;
ultrafiltration systems; nanofiltration, reverse osmosis;
systems with granular activated carbon;
chemical programs for the treatment and stabilization of boiler and cooling water, steam and condensate, water from recycling water supply systems;
control, measuring and analytical equipment.

The water purification and water treatment systems offered by the KF Center company are designed not only to remove mechanical impurities and suspended matter from water, but also individual elements:

hardness salts;
organic compounds;
manganese;
gland;
hydrogen sulfide, etc.

Areas of activity of the company "KF Center"

At the KF Center company you can purchase various water purification or water treatment systems, as well as order a number of additional services.

Firstly, this is, of course, professional advice on the selection of suitable equipment and technological processes for working with water in this area.

Secondly, you can order the design of complexes that include a wide variety of water treatment and water purification systems. In addition, the company will not only design them, but will also produce, deliver and carry out commissioning work itself.

Thirdly, the KF Center company offers corrective water treatment with reagents.

Basic (traditional) methods of water treatment.

The problem of water purification covers issues of physical, chemical and biological changes during treatment in order to make it suitable for drinking, that is, purifying and improving its natural properties.

Basic methods of water treatment

Water clarification

Disadvantages of coagulation, settling and filtration: costly and ineffective water treatment methods, which requires additional quality improvement methods.)

Water disinfection

Disinfection of water with strong oxidizing agents.

Currently, at housing and communal services facilities, water disinfection is usually chlorination water. If you drink tap water, you should know that it contains organochlorine compounds, the amount of which after the water disinfection procedure with chlorine reaches 300 μg/l. Moreover, this amount does not depend on the initial level of water pollution; these 300 substances are formed in water due to chlorination. Consumption of such drinking water can seriously affect your health. The fact is that when organic substances combine with chlorine, trihalomethanes are formed. These methane derivatives have a pronounced carcinogenic effect, which promotes the formation of cancer cells. When chlorinated water is boiled, it produces a powerful poison - dioxin. The content of trihalomethanes in water can be reduced by reducing the amount of chlorine used or replacing it with other disinfectants, for example, using granular activated carbon to remove organic compounds formed during water purification. And, of course, we need more detailed control over the quality of drinking water.

Ozonation

Disadvantages of ozonation: The bactericidal effect is short-lived, and in reaction with phenol it is even more toxic than chlorophenols, which is more dangerous for the body than chlorination.

Disinfection of water with bactericidal rays.

CONCLUSIONS

New technologies and innovative methods for improving water quality

The introduction of new technologies and innovative methods of water treatment makes it possible to solve a set of problems that ensure:

production of drinking water that meets established standards and GOSTs and meets consumer requirements;
reliability of water purification and disinfection;
effective uninterrupted and reliable operation of water treatment facilities;
reducing the cost of water purification and water treatment;
saving reagents, electricity and water for your own needs;
quality of water production.

New technologies for improving water quality include:

Disadvantages: consumes electricity, is not efficient enough and is expensive to maintain.

CONCLUSIONS

Methods of non-contact activation of liquid (NL). Resonance technologies.

Introduction

For many years and centuries, water treatment was not distinguished as a branch of technology, and even less as a branch of chemical technology. Empirically found techniques and methods of water purification were used, mainly anti-infective ones. And therefore, the history of water treatment is the history of adaptation for the preparation and purification of water of known chemical processes and technologies that have found or are finding their application. The preparation of water for drinking and industrial water supply is fundamentally different from other areas of chemical technology: water treatment processes take place in large volumes of water and with very small amounts of dissolved substances. This means that high water consumption requires the installation of large-sized equipment, and a small amount of substances extracted from water inevitably entails the use of “fine” methods of water treatment. Currently, the scientific foundations of water treatment technologies are being intensively developed, taking into account the specified specifics of this branch of technology. And such work is far from complete, if we can even talk about the final knowledge of water. It would be a huge exaggeration to say that advanced scientific and design forces, the best machine-building capabilities were aimed at meeting the needs of water treatment. On the contrary, attention to this industry and, therefore, financing was shown in the smallest amount, on a residual basis.

Water treatment has also experienced the trials that have befallen Russia over the past 12-15 years. Both customers and supplies of water treatment equipment are increasingly, so to speak, individualized. In past years, deliveries were, as a rule, wholesale, but now, mainly, small-scale and single. Not to mention what was absent most recently Russian production household filters and autonomous water supply systems, by definition supplied in one or more copies. And the import of such equipment was very scarce. This means that many people who were previously unfamiliar with it are involved in water treatment. In addition, given the small number of specialists in water treatment, many engineers who have received education in other specialties deal with water. The task of providing consumers with quality drinking water can hardly be called easy.

It is almost impossible to even briefly review all methods of water purification and water treatment. Here we wanted to draw the attention of readers to the most frequently used in practice in modern technologies at treatment plants of various water supply systems.

1. Properties and composition of water

Water is the most anomalous substance of nature. This common expression is due to the fact that the properties of water largely do not correspond to the physical laws that other substances obey. First of all, it is necessary to recall: when we talk about natural water, all judgments should be related not to water as such, but to aqueous solutions of various, in fact all, elements of the Earth. Until now, it has not been possible to obtain chemically pure water.

1.1 Physical properties of water

The polar asymmetric structure of water and the diversity of its associates determine the amazing anomalous physical properties of water. Water reaches its greatest density at positive temperatures; it has abnormally high heat of evaporation and heat of fusion, specific heat, boiling and freezing points. Big specific heat -4.1855 J/(g°C) at 15°C - helps regulate temperature on Earth due to the slow heating and cooling of water masses. Mercury, for example, has a specific heat capacity at 20°C of only 0.1394 J/(g°C). In general, the heat capacity of water is more than twice the heat capacity of any other chemical compound. This can explain the choice of water as a working fluid in the energy sector. Anomalous property of water - expansion of volume by 10% upon freezing ensures the floating of ice, that is, it again preserves life under the ice. Another extremely important property of water is its exceptionally large surface tension . Molecules on the surface of water experience intermolecular attraction on one side. Since the forces of intermolecular interaction in water are abnormally strong, each molecule “floating” on the surface of the water is, as it were, drawn into the water layer. Water has a surface tension of 72 mN/m at 25°C. In particular, this property explains the spherical shape of water under conditions of weightlessness, the rise of water in the soil and in the capillary vessels of trees, plants, etc.

Natural water - a complex disperse system containing a wide variety of mineral and organic impurities.

The quality of natural water in general refers to the characteristics of its composition and properties, which determine its suitability for specific types of water use, while the quality criteria are the characteristics by which the quality of water is assessed.

1.2. Suspended impurities

Suspended solids , present in natural waters, consist of particles of clay, sand, silt, suspended organic and inorganic substances, plankton and various microorganisms. Suspended particles affect water clarity.

The content of suspended impurities in water, measured in mg/l, gives an idea of the contamination of water with particles mainly with a nominal diameter of more than 1·10 - 4 mm. When the content of suspended substances in water is less than 2-3 mg/l or more than the specified values, but the nominal diameter of the particles is less than 1 × 10-4 mm, water pollution is determined indirectly by the turbidity of the water.

1.3. Turbidity and clarity

Turbidity water is caused by the presence of fine impurities caused by insoluble or colloidal inorganic and organic substances of various origins. Along with turbidity, especially in cases where the water has slight color and turbidity, and their determination is difficult, the indicator is used « transparency» .

1.4. Smell

Character and intensity of odor natural water is determined organoleptically. Based on their nature, odors are divided into two groups: natural origin (organisms living and dying in water, decaying plant debris, etc.); artificial origin (impurities of industrial and agricultural wastewater). Odors of the second group (artificial origin) are named by the substances that determine the odor: chlorine, gasoline, etc.

1.5. Taste and smack

Distinguish four types of water flavors : salty, bitter, sweet, sour. The qualitative characteristics of shades of taste sensations - taste - are expressed descriptively: chlorine, fishy, bitter, and so on. The most common salty taste of water is most often caused by sodium chloride dissolved in water, bitter by magnesium sulfate, sour by excess free carbon dioxide, etc.

1.6. Chroma

The water quality indicator, which characterizes the intensity of the color of water and is determined by the content of colored compounds, is expressed in degrees of the platinum-cobalt scale and is determined by comparing the color of the test water with standards. Chroma The temperature of natural waters is determined mainly by the presence of humic substances and ferric iron compounds, ranging from a few to thousands of degrees.

1.7. Mineralization

Mineralization - the total content of all mineral substances found during chemical analysis of water. The mineralization of natural waters, which determines their specific electrical conductivity, varies within wide limits. Most rivers have mineralization from several tens of milligrams per liter to several hundred. Their specific electrical conductivity varies from 30 to 1500 µS/cm. The mineralization of groundwater and salt lakes varies in the range from 40-50 mg/l to hundreds of g/l (the density in this case is already significantly different from unity). The specific electrical conductivity of atmospheric precipitation with mineralization from 3 to 60 mg/l is 10-120 µS/cm. Natural waters of mineralization are divided into groups. The fresh water limit - 1 g/kg - was established due to the fact that when mineralization exceeds this value, the taste of water is unpleasant - salty or bitter-salty.

1.8. Electrical conductivity

Electrical conductivity is a numerical expression of the ability of an aqueous solution to conduct electric current. The electrical conductivity of water depends mainly on the concentration of dissolved mineral salts and temperature.

Based on electrical conductivity values, one can approximately judge the mineralization of water.

Type of water Salinity Density,

1.9. Rigidity

Hardness of water is caused by the presence of calcium, magnesium, strontium, barium, iron, and manganese ions in water. But the total content of calcium and magnesium ions in natural waters is incomparably greater than the content of all other listed ions - and even their sum. Therefore, hardness is understood as the sum of the amounts of calcium and magnesium ions - the total hardness, which consists of the values of carbonate (temporary, eliminated by boiling) and non-carbonate (permanent) hardness. The first is caused by the presence of calcium and magnesium bicarbonates in water, the second by the presence of sulfates, chlorides, silicates, nitrates and phosphates of these metals. However, if the water hardness is more than 9 mmol/l, the content of strontium and other alkaline earth metals in the water must be taken into account.

According to the ISO 6107-1-8:1996 standard, which includes more than 500 terms, hardness is defined as the ability of water to form foam with soap. In Russia, water hardness is expressed in mmol/l. In hard water, ordinary sodium soap turns (in the presence of calcium ions) into insoluble “calcium soap”, forming useless flakes. And until all calcium hardness in the water is eliminated in this way, foam formation will not begin. For 1 mmol/l of water hardness, such water softening theoretically requires 305 mg of soap, practically up to 530. But, of course, the main troubles are from scale formation.

Classification of water by hardness (mmol/l): Water group Unit of measurement, mmol/l

Very soft………………..up to 1.5

Soft……………………….1.5 - 4.0

Medium hardness………… 4 - 8

Hard…………………... 8 - 12

Very hard……………….more than 12

1.10. Alkalinity

Alkalinity water is the total concentration of weak acid anions and hydroxyl ions contained in water (expressed in mmol/l), which react during laboratory tests with hydrochloric or sulfuric acids to form chloride or sulfate salts of alkali and alkaline earth metals. The following forms of water alkalinity are distinguished: bicarbonate (hydrocarbonate), carbonate, hydrate, phosphate, silicate, humate - depending on the anions of weak acids that determine the alkalinity.

Alkalinity of natural waters, the pH of which is usually

Since alkalinity in natural waters is almost always determined by bicarbonates, for such waters the total alkalinity is taken to be equal to carbonate hardness.

1.11. Organic matter

Range organic impurities very wide:

Humic acids and their salts - sodium, potassium, ammonium humates;

Some impurities of industrial origin;

Part of amino acids and proteins;

Fulvic acids (salts) and humic acids and their salts - humates of calcium, magnesium, iron;

Fats of various origins;

Particles of various origins, including microorganisms.

The content of organic substances in water is assessed using methods for determining water oxidability, organic carbon content, biochemical oxygen demand, and absorption in the ultraviolet region. The value characterizing the content of organic and mineral substances in water that are oxidized by one of the strong chemical oxidizing agents under certain conditions is called oxidability . There are several types of water oxidability: permanganate, bichromate, iodate, cerium (methods for determining the last two are rarely used). Oxidability is expressed in milligrams of oxygen, equivalent to the amount of reagent used to oxidize organic substances contained in 1 liter of water. In groundwater (artesian) there are practically no organic impurities, but in surface water there are decisively more “organics”.

2. Selection of water treatment methods

Water treatment methods should be selected by comparing the composition of the source water and its quality, regulated regulatory documents or determined by the water consumer. After preliminary selection of water purification methods, the possibilities and conditions of their use are analyzed based on the task at hand. Most often, the result is achieved through the gradual implementation of several methods. Thus, both the choice of water treatment methods themselves and their sequence are important.

There are about 40 water treatment methods. Only the most frequently used ones are discussed here.

2.1.Physico-chemical processes water treatment

These processes are characterized by the use of chemical reagents to destabilize and increase the size of the particles that form the pollution, after which the solid particles are physically separated from the liquid phase.

2.1.1. Coagulation and flocculation

Coagulation and flocculation are two completely different components of physical and chemical water treatment.

Coagulation - this is the stage during which destabilization of colloidal particles (similar to balls with a diameter of less than 1 micron) occurs.

The word coagulation comes from the Latin “coagulare”, which means “to agglomerate, stick together, accumulate.” In water treatment, coagulation is achieved by adding chemicals to a water suspension where dispersed colloidal particles are collected into large aggregates called flocs or microflocs.

Colloids are insoluble particles that are suspended in water. Small sizes (less than 1 micron) make these particles extremely stable. Particles can be of different origins:

Mineral: silt, clay, silica, metal hydroxides and salts, etc.

Organic: humic and fulvic acids, dyes, surface- active substances And

Note: Microorganisms such as bacteria, plankton, algae, viruses are also considered colloids.

The stability and, therefore, instability of suspended particles is a factor determined by different forces of attraction and repulsion:

Forces of intermolecular interaction

Electrostatic forces

By the gravity of the earth

Forces involved in Brownian motion

Coagulation is both a physical and chemical process. Reactions between particles and coagulant provide the formation of aggregates and their subsequent precipitation. Cationic coagulants neutralize the negative charge of colloids and form a loose mass called microflakes.

The coagulation mechanism can be reduced to two steps:

1- Charge neutralization: which corresponds to the reduction of electrical charges that have a repulsive effect on colloids.

2- Formation of particle aggregates.

Currently, mainly mineral coagulants are used. They are based mainly on iron or aluminum salts. These are the most commonly used coagulants. The charge of the cation here is created by metal ions, which are formed from iron or aluminum hydroxides upon contact with water. The main advantages of such coagulants are their versatility and low cost.

Coagulation - this is an intermediate, but very important stage in the process of physical and chemical purification of water and wastewater. This is the first step in the removal of colloidal particles, the main function of which is to destabilize the particles. Destabilization mainly consists of neutralizing the electrical charge present on the surface of the particle, which promotes the aggregation of colloids.

Flocculation - This is the stage during which destabilized colloidal particles (or particles formed during the coagulation stage) are collected into aggregates.

The flocculation stage can only take place in water where the particles have already been destabilized. This is the stage that logically follows coagulation. Flocculants, with their charge and very high molecular weight (long monomer chains), fix destabilized particles and aggregate them along the polymer chain. As a result, at the flocculation stage, an increase in the size of particles in the aqueous phase occurs, which is expressed in the formation of flocs.

The bonds between destabilized particles and the flocculant are, as a rule, ionic and hydrogen.

2.2. Water clarification by filtration

The initial stage of water treatment, as a rule, is its release from suspended impurities - water clarification, sometimes classified as pre-treatment.

There are several types of filtering:

- straining - pore sizes of the filter material smaller sizes trapped particles;

- film filtration - under certain conditions, after a certain initial period, the filter material is enveloped in a film of suspended substances, on which particles even smaller than the pore size of the filter material can be retained: colloids, small bacteria, large viruses;

- volumetric filtration - suspended particles, passing through a layer of filter material, repeatedly change the direction and speed of movement in the cracks between the granules and fibers of the filter material; Thus, the dirt holding capacity of the filter can be quite large - more than with film filtration. Filtration in fabric, ceramic, and almost all filters with non-woven fibrous filter elements is carried out according to the first two types mentioned; in fine-grained bulk filters - according to the second type, in coarse-grained bulk filters - according to the third.

2.2.1. Classification of filters with granular loading

Granular filters are used mainly for the purification of liquids in which the solid phase content is negligible and the sediment is of no value; the main purpose of the filters is to clarify natural water. They are the ones most widely used in water treatment technology. Classification of filters according to a number of basic characteristics:

♦ filtration speed:

Slow (0.1-0.3 m/h);

Ambulances (5-12 m/h);

Super high-speed (36-100 m/h);

♦ the pressure under which they work:

Open or free-flowing;

Pressure;

♦ number of filter layers:

Single layer;

Double layer;

Multilayer.

The most effective and economical are multilayer filters, in which, to increase dirt holding capacity and filtration efficiency, the load is made up of materials with different densities and particle sizes: on top of the layer there are large light particles, at the bottom there are small heavy ones. With downward filtration, large contaminants are retained in the upper loading layer, and the remaining small ones are retained in the lower layer. In this way, the entire loading volume works. Clarifying filters are effective at retaining particles >10 microns in size.

2.2.2. Filtration technology

Water containing suspended particles, moving through a granular load that retains suspended particles, is clarified. The efficiency of the process depends on the physicochemical properties of impurities, filter media and hydrodynamic factors. Contaminants accumulate in the thickness of the load, the free pore volume decreases and the hydraulic resistance of the load increases, which leads to an increase in pressure losses in the load.

In general, the filtration process can be divided into several stages: transfer of particles from the water stream to the surface of the filter material; fixation of particles on grains and in the cracks between them; separation of fixed particles with their transition back into the water flow. The removal of impurities from water and their fixation on the loading grains occurs under the influence of adhesion forces. The sediment formed on the loading particles has a fragile structure, which can be destroyed under the influence of hydrodynamic forces. Some of the previously adhered particles are torn off from the grains of the load in the form of small flakes and transferred to subsequent layers of the load (suffusion), where they are again retained in the pore channels. Thus, the process of water clarification should be considered as the total result of the process of adhesion and suffusion. Lightening in each elementary loading layer occurs as long as the intensity of particle adhesion exceeds the intensity of separation. As the upper layers of the load become saturated, the filtration process moves to the lower ones; the filtration zone seems to move in the direction of flow from the area where the filter material is already saturated with contaminants and the process of suffusion predominates to the area of the fresh load.

Then there comes a time when the entire filter loading layer is saturated with water contaminants, and the required degree of water clarification is not achieved. The concentration of suspended matter at the loading outlet begins to increase.

The time during which water clarification to a given degree is achieved is called loading protection time . When it is reached or when the maximum pressure loss is reached, the clarification filter must be switched to the loosening washing mode, when the load is washed with a reverse flow of water, and contaminants are discharged into the drain.

The possibility of retaining coarse suspended matter by a filter depends mainly on its mass; fine suspension and colloidal particles - from surface forces. The charge of suspended particles is important, since colloidal particles of the same charge cannot combine into conglomerates, enlarge and settle: the charge prevents their approach. This “alienation” of particles is overcome by artificial coagulation. As a result of coagulation, aggregates are formed - larger (secondary) particles, consisting of a cluster of smaller (primary) ones. As a rule, coagulation (sometimes, additionally, flocculation) is carried out in settling tanks-clarifiers.

Often this process is combined with water softening by liming, or soda liming, or caustic soda softening. In conventional clarification filters, film filtration is most often observed. Volumetric filtration is organized in two-layer filters and in so-called contact clarifiers. The filter is filled with a lower layer of quartz sand with a grain size of 0.65-0.75 mm and an upper layer of anthracite with a grain size of 1.0-1.25 mm. A film does not form on the upper surface of a layer of large anthracite grains; suspended impurities penetrate deep into the layer - into the pores and are deposited on the surface of the grains. Suspended substances that have passed through the anthracite layer are retained by the lower layer of sand. When loosening the filter, the layers of sand and anthracite are not mixed, since the density of anthracite is half the density of quartz sand.

3. Ion exchange purification methods

Ion exchangeis the process of extracting some ions from water and replacing them with others. The process is carried out using ion exchange substances - artificially granular substances insoluble in water, special non-woven materials or natural zeolites that have acidic or basic groups in their structure that can be replaced by positive or negative ions.

Ion exchange technology is the most used today for softening and demineralization of water. This technology makes it possible to achieve water quality that meets the standards of various industrial and energy facilities.

The purification of acidic wash waters by the ion exchange method is based on the ability of water-insoluble ion exchangers to enter into ion exchange with water-soluble salts, extracting their cations or anions from solutions and releasing into the solution an equivalent amount of ions, with which the cation and anion exchangers are periodically saturated during regeneration.

Ion exchange method Water purification is used for desalting and purifying water from metal ions and other impurities. The essence of ion exchange lies in the ability of ion exchange materials to take ions from electrolyte solutions in exchange for an equivalent amount of ion exchanger ions.

Water purification is carried out by ion exchangers - synthetic ion exchange resins made in the form of granules measuring 0.2...2 mm. Ion exchangers are made from water-insoluble polymer substances that have a mobile ion (cation or anion) on their surface, which under certain conditions enters into an exchange reaction with ions of the same sign contained in water.

Selective absorption of molecules by the surface of a solid adsorbent occurs due to the action of unbalanced surface forces of the adsorbent on them.

Ion exchange resins have the ability to regenerate. After the working exchange capacity of the ion exchanger is depleted, it loses the ability to exchange ions and must be regenerated. Regeneration is carried out with saturated solutions, the choice of which depends on the type of ion exchange resin. Recovery processes, as a rule, occur automatically. Regeneration usually takes about 2 hours, of which 10-15 minutes for loosening, 25-40 minutes for filtering the regenerating solution, and 30-60 minutes for washing. Ion exchange purification is carried out by sequential filtration of water through cation exchangers and anion exchangers.

Depending on the type and concentration of impurities in water and the required purification efficiency, various schemes of ion exchange plants are used.

3.1. Cationation

Cationation , as the name suggests, is used to extract dissolved cations from water, i.e. cationization - the process of water treatment using the ion exchange method, as a result of which cations are exchanged. Depending on the type of ions (H+ or Na+) located in the volume of the cation exchanger, two main types of cationization are distinguished: sodium cationization and hydrogen cationization.

3.1.1. Sodium cationization

Sodium cation exchange method used to soften water with a suspended solids content of no more than 8 mg/l and a water color of no more than 30 degrees. Water hardness decreases with one-stage sodium cationization to values of 0.05 - 0.1 mEq/l, with two-stage sodium cationization - to 0.01 mEq/l. The process of sodium cationization is described by the following exchange reactions:

Regeneration of Na-cation exchanger is achieved by filtering a 5-8% solution of table salt through it at a speed of 3-4 m/h.

Advantages of table salt as a regeneration solution:

1. cheap;

2. accessibility;

3. regeneration products are easily disposed of.

3.1.2. Hydrogen cationization

Hydrogen cation exchange method used for deep water softening. This method is based on filtering the treated water through a layer of cation exchanger containing hydrogen cations as exchange ions.

During hydrogen cationization of water, the pH of the filtrate is significantly reduced due to the acids formed during the process. Carbon dioxide released during softening reactions can be removed by degassing. Regeneration of N-cation exchanger in this case is carried out with a 4 - 6% acid solution.

3.1.3. Other cationization methods

Sodium-chlorine ionization method used when it is necessary to reduce the total hardness, total alkalinity and mineralization of the source water, increase the criterion of potential alkaline aggressiveness (reduce the relative alkalinity) of boiler water, reduce carbon dioxide in steam and the purging value of steam boilers - by filtering sequentially through a layer of sodium cation resin in one filter and through layers: first - chlorine anion exchanger and then - sodium cation exchanger in another filter.

Hydrogen-sodium-cationization (combined, parallel or sequential with normal or “starved” regeneration of hydrogen-cation exchange filters) - to reduce the total hardness, total alkalinity and mineralization of water, as well as increase the criterion for the potential alkaline aggressiveness of boiler water, reduce the carbon dioxide content in steam and reduce boiler blowdown.

Ammonium-sodium-cationization used to achieve the same goals as sodium chlorine ionization.

3.2. Anionization

Anionization , as the name suggests, is used to extract dissolved anions from water. Water that has already undergone preliminary cationization is subject to anionization. Regeneration of the anion exchange filter is usually carried out with alkali (NaOH). After the working exchange capacity of the anion exchanger is exhausted, it is regenerated. Both strongly and weakly basic anion exchangers are capable of absorbing strong acid anions from water. Anions of weak acids - carbonic and silicon - are absorbed only by strong basic anion exchangers. For strong basic anion exchangers, a NaOH solution is used as a regenerant (therefore the process is also called hydroxide anionization). The mechanism of ion exchange and the influence of various factors on the technology of the anionization process are in many ways similar to their influence on cationization processes, but there are also significant differences. Weak base anion exchangers are capable of sorption of different anions to varying degrees. As a rule, a certain series is observed in which each previous ion is absorbed more actively and in greater quantities than the next.

In the technological chain of demineralization by ionization, after hydrogen cation and weakly basic anion exchange filters, strong basic anion exchange filters are provided if it is necessary to remove silicic acid anions and - sometimes - carbonic acid anions from water. The best results are obtained at low pH values and almost complete decation of water. The use of anion exchangers when the source water contains organic impurities has its own characteristics.

3.3. Desalination of water using the ionic method

To purify wastewater from anions of strong acids, a technological scheme of one-stage H-cationization and OH-anionization is used using a strong acid cation exchanger and a weakly basic anion exchanger.

For deeper purification of wastewater, including the removal of salts, one- or two-stage H-cationization on a strong-acid cation exchanger is used, followed by two-stage OH-anionization on a weak- and then a strong-base anion exchanger.

When wastewater contains a large amount of carbon dioxide and its salts, the capacity of the strong base anion exchanger quickly depletes. To reduce depletion, wastewater after the cation exchange filter is degassed in special degassers with a nozzle made of Raschig rings or in other devices. If it is necessary to ensure a pH value of ~ 6.7 and purify wastewater from anions of weak acids, instead of second-stage anion exchange filters, a mixed-action filter loaded with a mixture of a strong acid cation exchanger and a strongly basic anion exchanger is used.

The method of desalting water by ion exchange is based on sequential filtering of water through an H-cation exchange resin filter, and then an OH-, HCO 3 - or CO 3 - anion exchange resin filter. In the H-cation exchange resin filter, the cations contained in the water are exchanged for hydrogen cations. In OH-anion exchange filters, which water passes after H-cation exchange exchangers, the anions of the formed acids are exchanged for OH- ions. Requirements for water supplied to H-OH filters:

suspended substances - no more than 8 mg/l;

sulfates and chlorides - up to 5 mg/l;

color - no more than 30 degrees;

permanganate oxidation - up to 7 mg O 2 /l;

total iron - no more than 0.5 mg/l;

petroleum products - none;

free active chlorine - no more than 1 mg/l.

If the source water does not meet these requirements, then it is necessary to carry out preliminary water treatment.

In accordance with the required depth of water desalination, one-, two- and three-stage installations are designed, but in all cases, strongly acidic H-cation exchangers with high exchange capacity are used to remove metal ions from water.

Single-stage ion exchange units are used to produce water with a salt content of up to 1 mg/l (but not more than 20 mg/l).

In single-stage ion exchange installations, water is sequentially passed through a group of filters with an H-cation exchanger, and then through a group of filters with a weakly basic anion exchanger; free carbon monoxide (CO 2) is removed in a degasser installed after cation or anion filters if they are regenerated with a solution of soda or bicarbonate. Each group must have at least two filters.

3.4. Demineralization of water by ionization

Water demineralization - a method designed to reduce water mineralization, including total hardness, total alkalinity, and the content of silicon compounds. The ion exchange method of water demineralization is based on sequential filtering of water through a hydrogen cation exchanger and then an HCO 3 -, OH - or CO 3 -anion exchange filter. An equivalent amount of acid is formed in the filtrate from the anions to which the cations were bound. The CO 2 formed during the decomposition of hydrocarbonates is removed in decarbonizers.

In anion filters (hydroxide anionization), the anions of the formed acids are exchanged for OH ions - (retained by the filter). The result is demineralized (desalted) water.

This method is actually “independent”, synthetic. It represents a schematic series of options for combining varying degrees of complexity - depending on the purpose of water treatment - hydrogen cationization and hydroxide anionization.

3.5. Conditions for using ion exchange units

Ion exchange units should be supplied with water containing salts - up to 3 g/l, sulfates and chlorides - up to 5 mmol/l, suspended substances - no more than 8 mg/l, color - no higher than 30 degrees, permanganate oxidability - up to 7 mgO/ l. In accordance with the required depth of water desalination, one-, two- and three-stage installations are designed, but in all cases, strong acid hydrogen cation exchangers are used to remove metal ions from water. For industrial and energy consumers, water can be prepared using a one-stage scheme - one cation exchange and one anion exchange filters; according to a two-stage scheme - respectively, two cation-exchange and two anion-exchange filters; according to a three-stage scheme, and the third stage can be designed in two options: separate cation exchange and anion exchange filters or combining a cation exchange and anion exchange in one filter.

After a one-stage scheme: water salinity - 2-10 mg/l; specific electrical conductivity - 1-2 µS/cm; the content of silicon compounds does not change. A two-stage scheme is used to obtain water with a salt content of 0.1-0.3 mg/l; specific electrical conductivity 0.2-0.8 µS/cm; content of silicon compounds up to 0.1 mg/l. The three-stage scheme allows you to reduce the salt content to 0.05-0.1 mg/l; specific electrical conductivity - up to 0.1-0.2 µS/cm; silicic acid concentration - up to 0.05 mg/l. For household filters, single-stage demineralization is used - joint loading of the filter with cation exchange resin and anion exchange resin.

3.6. Mixed filters

Combining a cation exchanger and an anion exchanger in one apparatus makes it possible to achieve a high degree of purification: almost all ions in the solution are extracted from water in one pass. Purified water has a neutral reaction and low salt content. After saturation with ions, the mixture of ion exchangers - for regeneration - must first be divided into cation exchanger and anion exchanger, which have different densities. Separation is carried out by the hydrodynamic method (water flow from bottom to top) or by filling the filter with a concentrated 18% reagent solution. Currently, the main foreign manufacturers produce sets of monodisperse resin granules specially selected for density and size, providing a high degree of separation and stability of performance.

Due to the complexity of the operations of separating a mixture of cation exchanger and anion exchanger and their regeneration, such devices are used mainly for the purification of low-salinity waters and the additional purification of water previously desalted by reverse osmosis, when regeneration is carried out rarely or the ion exchangers are used once.

3.7. Features of ion exchange technology

Historically, almost all designs of ion exchange filters are parallel-precise (direct-flow), that is, the treated water and the regenerating solution move in the filter in the same direction - from top to bottom. As the regeneration solution moves from top to bottom through the ion exchanger layer, the concentration pressure - the concentration difference between previously retained ions (for example, calcium and magnesium) and the ions of the regenerating solution (for example, sodium) that displace them - becomes smaller and smaller.

At the end of its path, the “weak” regeneration solution encounters a layer of ion exchanger containing a certain, albeit small, amount of ions that need to be displaced from the ion exchanger. There is no displacement. As a result, the next stream of treated water does not reach the required quality.

This feature of ion exchange technology, as well as the properties of ion exchangers, regenerants and lyotropic series, determine the fundamental disadvantages of ion exchange technology for water purification: high consumption of reagents, water for washing the ion exchanger from regeneration solution residues and a large amount of wastewater, the quality of which does not meet the requirements of regulatory documents.

A way out of the situation was found by technologists who proposed two-stage filtration for sodium cationization and three-stage filtration for demineralization by ionization. Parallel-countercurrent filtration can be considered a type of two-stage softening: despite the name, parallel-flow filtration is carried out in each of the pair of filters.

Decarbonization- removal of carbon monoxide released in the processes of hydrogen cationization and anionization.

Removing it from water before strong basic anion exchange filters is necessary, since in the presence of CO 2 in water, part of the working exchange capacity of the anion exchanger will be spent on absorbing CO 2.

Traditionally, to remove carbon dioxide from water, decarbonizers are used - devices filled with various water distributors (more often - bulk, for example, Raschig, Pall rings, etc.), called nozzles, or without fillers, and blown with air towards water flow. Depending on the design, the decarbonizer can be installed after the first or second hydrogen cationization stage, or after the first (weak base) anionization stage. The latter scheme is more often used in foreign developments. Ejector (vacuum, jet) devices are becoming widespread. Their work is based on creating a high-speed flow in an ejector device, in which the flow is evacuated, followed by air being sucked into the water and blown off. With small dimensions, this design provides greater productivity and high gas removal efficiency. In this case - free CO 2. At small water treatment stations and with a low content of bicarbonates in the source water, a water treatment scheme without decarbonizers is used.

5. Baromembrane water treatment methods

Demineralization of water by ion exchange and thermal demineralization (distillation) make it possible to desalinate water and almost completely desalt it. However, the use of these methods revealed the presence of disadvantages: the need for regeneration, bulky and expensive equipment, expensive ion exchangers, etc. In this regard, baromembrane methods of water treatment have become widespread.

The group of baromembrane methods includes reverse osmosis, microfiltration, ultrafiltration and nanofiltration. Reverse osmosis (pore sizes 1-15 Å , operating pressure 0.5-8.0 MPa) is used for demineralization of water, retains almost all ions by 92-99%, and with a two-stage system, up to 99.9%. Nanofiltration (pore sizes 10-70Å , operating pressure 0.5-8.0 MPa) is used to separate dyes, pesticides, herbicides, sucrose, some dissolved salts, organic substances, viruses, etc. Ultrafiltration (pore sizes 30-1000Å , operating pressure 0.2-1.0 MPa) is used for separating some colloids (silicon, for example), viruses (including polio), coal soot, separating milk into fractions, etc. Microfiltration (pore sizes 500-20000Å , operating pressure from 0.01 to 0.2 MPa) is used for separating some viruses and bacteria, fine pigments, activated carbon dust, asbestos, dyes, separating water-oil emulsions, etc. The larger the pores are formed in the membrane, the more understandable the process of filtration through the membrane is, the more it approaches the so-called mechanical filtration in its physical meaning.

The intermediate group is formed by the so-called track membranes, obtained by irradiating Mylar (polyethylene terephthalant) films in a cyclotron with a flow of heavy ions. After exposure of the film to ultraviolet rays and etching with alkali, pores with a diameter of 0.2-0.4 microns (mostly 0.3 microns) are formed in the film.

5.1. Reverse osmosis

Reverse osmosis - one of the most promising methods of water treatment, the advantages of which lie in low energy consumption, simplicity of design of devices and installations, their small dimensions and ease of operation; It is used for desalting waters with a salt content of up to 40 g/l, and the boundaries of its use are constantly expanding.

The essence of the method. If the solvent and solution are separated by a semi-permeable partition that allows only molecules of the solvent, then the solvent will begin pass through the partition into the solution until as long as the concentrations of solutions on both sides membranes are not aligned. The process of spontaneous flow of substances through a semi-permeable membrane separating two solutions different concentrations (a special case is a pure solvent and a solution), called by osmosis (from Greek: osmos - push, pressure). If you create back pressure over the solution, rate of solvent transfer through the membrane will decrease. When equilibrium is established, the corresponding pressure can serve as a quantitative characteristic of the reverse osmosis phenomenon. It is called osmotic pressure and equal to the pressure that must be applied to solution to bring it into equilibrium with a pure solvent separated from it by a semi-permeable partition. In relation to water treatment systems, where the solvent is water, the process is reversed Osmosis can be represented as follows: if from the side of natural water flowing through the apparatus with a certain content of impurities apply pressure exceeding osmotic pressure, then water will leak through the membrane and accumulate on the other side, and impurities remain with the source water, their concentration will be increase.

In practice, membranes are usually not ideally semi-permeable and there is some transfer of solute across the membrane.

Osmotic pressures of solutions can reach tens of MPa. The operating pressure in reverse osmosis units must be significantly higher, since their performance is determined by the driving force of the process - the difference between the operating and osmotic pressure. Thus, at an osmotic pressure of 2.45 MPa for sea water, containing 3.5% salts, the operating pressure in desalination plants is recommended to be maintained at 6.85-7.85 MPa.

5.2. Ultrafiltration

Ultrafiltration - the process of membrane separation, as well as fractionation and concentration of solutions. It occurs under the influence of the pressure difference (before and after the membrane) of solutions of high and low molecular weight compounds.

Ultrafiltration borrowed methods for producing membranes from reverse osmosis, and is also largely similar to it in terms of hardware design. The difference lies in much higher requirements for the removal from the membrane surface of a concentrated solution of a substance that can form gel-like layers and poorly soluble precipitates in the case of ultrafiltration. Ultrafiltration according to the process flow diagram and parameters is an intermediate link between filtration and reverse osmosis.

The technological capabilities of ultrafiltration are in many cases much wider than those of reverse osmosis. Thus, with reverse osmosis, as a rule, there is a general retention of almost all particles. However, in practice, the task of selective separation of solution components, that is, fractionation, often arises. The solution to this problem is very important, since it is possible to separate and concentrate very valuable or rare substances (proteins, physiologically active substances, polysaccharides, complexes of rare metals, etc.). Ultrafiltration, in contrast to reverse osmosis, is used to separate systems in which the molecular weight of dissolved components is much greater than the molecular weight of the solvent. For example, for aqueous solutions it is assumed that ultrafiltration is applicable when at least one of the components of the system has a molecular weight of 500 or more.

The driving force behind ultrafiltration is the pressure difference on both sides of the membrane. Typically, ultrafiltration is carried out at relatively low pressures: 0.3-1 MPa. In the case of ultrafiltration, the role of external factors increases significantly. Thus, depending on the conditions (pressure, temperature, intensity of turbulization, solvent composition, etc.), on the same membrane it is possible to achieve complete separation of substances, which is impossible with a different combination of parameters. The limitations of ultrafiltration include: narrow technological range - the need to accurately maintain process conditions; a relatively low concentration limit, which for hydrophilic substances usually does not exceed 20-35%, and for hydrophobic substances - 50-60%; short (1-3 years) membrane service life due to sedimentation in the pores and on their surface. This leads to contamination, poisoning and disruption of the membrane structure or deterioration of their mechanical properties.

5.3. Membranes

The determining factors in the implementation of membrane methods are the development and production of semi-permeable membranes that meet the following basic requirements:

High separating ability (selectivity);

High specific productivity (permeability);

Chemical resistance to the components of the separated system;

Consistency of characteristics during operation;

Sufficient mechanical strength to meet the conditions of installation, transportation and

membrane storage;

Low cost.

There are currently two main types of membranes on the market, made from cellulose acetate (a mixture of mono-, di- and triacetate) and aromatic polyamides. Based on their shape, membranes are divided into tubular, sheet (spiral-rolled) and made in the form of hollow fibers. Modern reverse osmosis membranes - composite - consist of several layers. The total thickness is 10-150 microns, and the thickness of the layer that determines the selectivity of the membrane is no more than 1 micron.

From a practical point of view, two process indicators are of greatest interest: the solute retention coefficient (selectivity), and the productivity (volume flow) through the membrane. Both of these indicators ambiguously characterize the semi-permeable properties of the membrane, since they largely depend on the process conditions (pressure, hydrodynamic conditions, temperature, etc.).

6. Methods for deferrizing water

Water with a high iron content has an unpleasant taste, and the use of such water in production processes (textile industry, paper production, etc.) is unacceptable, as it leads to the appearance of rust spots and streaks on the surface. finished products. Iron and manganese ions contaminate ion exchange resins, so in most ion exchange processes the previous stage of water treatment is their removal. IN thermal power equipment(steam and hot water boilers, heat exchangers) iron is the source of the formation of iron scale deposits on heating surfaces. In water supplied for treatment to baromembrane, electrodialysis, and magnetic devices, the iron content is always limited. Purifying water from iron compounds is in some cases a rather complex task that can only be solved comprehensively. This circumstance is primarily associated with the variety of forms of existence of iron in natural waters. To determine the most effective and economical deferrization method for a particular water, you need to carry out a trial iron removal. The method of water deferrization, design parameters and doses of reagents should be adopted based on the results of technological research carried out directly at the water supply source.

To remove iron from surface water, only reagent methods followed by filtration are used. Deferrization of groundwater is carried out by filtration in combination with one of the methods of pre-treatment of water:

Simplified aeration;

Aeration using special devices;

Coagulation and clarification;

The introduction of oxidizing reagents such as chlorine, sodium or calcium hypochlorite, ozone,

potassium permanganate.

With a reasoned justification, cationization, dialysis, flotation, electrocoagulation and other methods are used.

To remove iron contained in the form of colloidal iron hydroxide or in the form of colloidal organic compounds, such as iron humates, from water, coagulation with aluminum sulfate or aluminum oxychloride, or ferrous sulfate with the addition of chlorine or sodium hypochlorite is used.

Sand, anthracite, sulfonated coal, expanded clay, pyrolusite, as well as filter materials treated with a catalyst that accelerates the oxidation of divalent iron into ferric iron are mainly used as filter fillers. Recently, fillers with catalytic properties have become increasingly widespread.

If colloidal divalent iron is present in water, it is necessary to carry out trial deferrization . If it is not possible to carry it out at the first stage of design, choose one of the above methods based on the trial deferrization carried out in the laboratory or experience with similar installations.

7. Demanganization of water

Manganese is present in large quantities in the earth's crust and is usually found together with iron. The content of dissolved manganese in underground and surface waters, poor in oxygen, reaches several mg/l. Russian sanitary standards limit the level of maximum permissible manganese content in drinking water to 0.1 mg/l.

In some European countries the requirements are stricter: no more than 0.05 mg/l. If the manganese content is higher than these values, the organoleptic properties of water deteriorate. When manganese values exceed 0.1 mg/l, stains appear on sanitary products, as well as an undesirable taste in water. A sediment forms on the inner walls of the pipelines, which peels off in the form of a black film.

In groundwater, manganese is found in the form of highly soluble salts in the divalent state. To remove manganese from water, it must be converted into an insoluble state by oxidation into the tri- and tetravalent form. Oxidized forms of manganese hydrolyze to form practically insoluble hydroxides.

For effective oxidation of manganese with oxygen, it is necessary that the pH value of the purified water be at the level of 9.5-10.0. Potassium permanganate, chlorine or its derivatives (sodium hypochlorite), ozone allow the demagganization process to be carried out at lower pH values of 8.0-8.5. To oxidize 1 mg of dissolved manganese, 0.291 mg of oxygen is needed.

7.1. Demanganization methods

Deep aeration followed by filtration. At the first stage of purification from water under vacuum extract free carbon dioxide, which promotes increasing the pH value to 8.0-8.5. For this purpose use a vacuum ejection apparatus, when In this case, in its ejection part, water is dispersed and saturated with air oxygen. Next, the water is sent for filtration through a granular load, for example, quartz sand. This purification method is applicable when the permanganate oxidation of the source water is no more than 9.5 mgO/l. Must be present in water divalent iron, the oxidation of which produces iron hydroxide, which adsorbs Mn 2+ and catalytically oxidizes it.

The concentration ratio / should not be less than 7/1. If this ratio is not met in the source water, then ferrous sulfate (iron sulfate) is additionally dosed into the water.

Demanganation with potassium permanganate. The method is applicable to both surface and groundwater. When potassium permanganate is added to water, dissolved manganese is oxidized with the formation of slightly soluble manganese oxide. Precipitated manganese oxide in the form of flakes has a highly developed specific density, which determines its high sorption properties. Sediment is good a catalyst that allows demangation during pH = 8.5.

As already noted, potassium permanganate ensures the removal of not only manganese, but also iron in various forms from water. Odors are also removed and the taste of water is improved due to sorption properties.

After potassium permanganate, a coagulant is introduced to remove oxidation products and suspended solids and then filtered using a sand bed. When purifying manganese from groundwater, activated silicic acid or flocculants are introduced in parallel with potassium permanganate. This allows the manganese oxide flakes to become larger.

8. Water disinfection

Water disinfection There are sanitary measures to destroy bacteria and viruses in water that cause infectious diseases. There are chemical, or reagent, and physical, or reagent-free, methods of water disinfection. The most common chemical methods of water disinfection include chlorination and ozonation of water, and physical methods include disinfection with ultraviolet rays. Before disinfection, water is usually subjected to water treatment, which removes helminth eggs and a significant part of microorganisms.

With chemical methods of water disinfection, in order to achieve a lasting disinfecting effect, it is necessary to correctly determine the dose of the administered reagent and ensure a sufficient duration of its contact with water. The dose of the reagent is determined by trial disinfection or calculation methods. To maintain the required effect with chemical methods of water disinfection, the dose of the reagent is calculated in excess (residual chlorine, residual ozone), guaranteeing the destruction of microorganisms that enter the water some time after disinfection.

In the current practice of drinking water disinfection chlorination most common. In the USA, 98.6% of water (the vast majority) is chlorinated. A similar picture occurs in Russia and other countries, i.e. in the world, in 99 out of 100 cases, either pure chlorine or chlorine-containing products are used for disinfection

This popularity of chlorination is also due to the fact that this is the only method that ensures the microbiological safety of water at any point in the distribution network at any time due to the aftereffect . This effect lies in the fact that after the action of introducing chlorine molecules into water (“after-effect”), the latter retain their activity in relation to microbes and inhibit their enzyme systems along the entire route of water through water supply networks from the water treatment facility (water intake) to each consumer. Let us emphasize that the aftereffect is inherent only to chlorine.

Ozonation is based on the property of ozone to decompose in water with the formation of atomic oxygen, which destroys the enzyme systems of microbial cells and oxidizes some compounds that give water an unpleasant odor (for example, humic bases). The amount of ozone required for water disinfection depends on the degree of water contamination and is 1-6 mg/l with contact for 8-15 minutes; the amount of residual ozone should be no more than 0.3-0.5 mg/l, because a higher dose gives the water a specific odor and causes corrosion of water pipes. Due to the high energy consumption, the use of complex equipment and highly qualified technical supervision, ozonation has found application for water disinfection only for centralized water supply to special-purpose facilities.

Of the physical methods of water disinfection, the most widespread disinfection with ultraviolet rays , the bactericidal properties of which are due to their effect on cellular metabolism and especially on the enzyme systems of the bacterial cell. Ultraviolet rays destroy not only vegetative but also spore forms of bacteria and do not change the organoleptic properties of water. A necessary condition for the effectiveness of this method of disinfection is the colorlessness and transparency of the disinfected water, the disadvantage is the lack of aftereffect. Therefore, water disinfection with ultraviolet rays is used mainly for underground and sub-channel waters. To disinfect water from open water sources, a combination of ultraviolet rays with small doses of chlorine is used.

Of the physical methods of individual water disinfection, the most common and reliable is boiling , in which, in addition to the destruction of bacteria, viruses, bacteriophages, antibiotics and other biological factors often contained in open water sources, gases dissolved in water are removed and water hardness is reduced. The taste of water changes little when boiled.

When monitoring the effectiveness of water disinfection in water pipelines, they proceed from the content of saprophytic microflora and, in particular, E. coli in the disinfected water, because all known pathogens of human infectious diseases spread by water (cholera, typhoid fever, dysentery) are more sensitive to the bactericidal action of chemical and physical water disinfectants than E. coli. Water is considered suitable for water use if it contains no more than 3 E. coli in 1 liter. At water supply stations using chlorination or ozonation, the content of residual chlorine or ozone is checked every 1 hour (or 30 minutes) as an indirect indicator of the reliability of water disinfection.

In Russia, there is a serious situation with the technical condition of water treatment complexes of centralized water intakes, which in many cases were designed and built 70-80 years ago. Their wear and tear increases every year, and more than 40% of the equipment requires complete replacement. An analysis of emergency situations shows that 57% of accidents at water and wastewater infrastructure facilities occur due to the dilapidation of equipment, so its further operation will lead to a sharp increase in accidents, the damage from which will significantly exceed the costs of their prevention. The situation is aggravated by the fact that due to the deterioration of the networks, the water in them is subject to secondary contamination and requires additional cleaning and disinfection. The situation with centralized water supply to the population in rural areas is even worse.

This gives grounds to call the problem of water supply hygiene, i.e., providing the population with good-quality, reliably disinfected water, as the most important problem requiring a comprehensive and most effective solution. Safe drinking water as defined by published World Organization Health Guidelines for Drinking Water Quality should not pose any health risks as a result of its consumption over a lifetime, including varying human vulnerabilities to disease at different stages of life. Those most at risk for waterborne diseases include infants and young children, people who are in poor health or living in unsanitary conditions, and the elderly.

All technological schemes for water purification and disinfection must be based on the basic criteria for the quality of drinking water: drinking water must be epidemiologically safe, harmless in chemical composition and have favorable organoleptic (taste) properties. These criteria form the basis of regulations in all countries (in Russia, SanPiN 2.14.1074-01). Let us dwell on the main most commonly used disinfectants: chlorination, ozonation and ultraviolet disinfection of water.

8.1. Water chlorination

In the last decade in Russia there has been an increased interest in water treatment facilities from the point of view of lobbying corporate business interests. Moreover, these discussions are justified by good intentions to provide the population with quality water. Under such reasoning about the need to consume clean water, an attempt is made to introduce senseless and unfounded innovations in violation of proven technologies and SanPiN 2.14.1074-01, which meets the highest world standards and requires mandatory presence of chlorine in drinking water of centralized water supply systems (remember the aftereffect that is unique to chlorine). Therefore, it is time to dispel the misconceptions on which the health of the nation depends.

In addition to chlorine, its compounds are used to disinfect water, of which sodium hypochlorite is most often used.

Sodium hypochlorite - NaCIO. In industry, sodium hypochlorite is produced as various solutions with different concentrations. Its disinfectant effect is primarily based on the fact that when dissolved Sodium hypochlorite, just like chlorine, forms hypochlorite when dissolved in water. It has a direct disinfecting and oxidizing effect.

Various brands of hypochlorite are used in the following areas:

. grade A solution according to GOST 11086-76 is used in the chemical industry to degrease drinking water and water for swimming pools, as well as for bleaching and disinfection;

. solution grade B according to GOST 11086-76 is used in the vitamin industry, as an oxidizing agent for bleaching fabrics;

. grade A solution according to specifications is used to avoid contamination of waste and natural waters in the domestic and drinking water supply. This solution is also used to disinfect the water of fishery reservoirs, produce bleaching agents and carry out disinfection in the food industry;

. grade B solution according to specifications is used for disinfection of areas that have been contaminated with fecal discharges, household and food waste; it is also very good for disinfecting wastewater;

. solution grade G, B according to the specifications is used for disinfection of water in a fishery reservoir;

. a solution of grade E according to the specifications is used for disinfection in the same way as in grade A according to the specifications. It is also very common in catering establishments, in health care institutions, for the disinfection of wastewater, drinking water, bleaching, at civil defense facilities, etc.

Attention! Precautionary measures: sodium hypochlorite solution GOST 11086-76 grade A is a very strong oxidizing agent; if it comes into contact with the skin, it can cause a burn; if it accidentally gets into the eyes, it can cause irreversible blindness.

When heated above 35°C, sodium hypochlorite decomposes with the subsequent formation of chlorates and the separation of chlorine and oxygen. MPC of chlorine in the working area environment - 1 mg/m3; in populated areas: 0.1 mg/m3 - maximum one-time and 0.03 mg/m3 - daily.

Sodium hypochlorite is non-flammable and non-explosive. But, sodium hypochlorite in accordance with GOST 11086-76 grade A, upon contact with an organic combustible substance (sawdust, rags, wood) during drying, can cause sudden spontaneous combustion.

Personal protection of personnel must be carried out using special clothing and personal protective equipment: a gas mask of grade B or BKF, rubber gloves and goggles.

If the skin and mucous membranes are exposed to sodium hypochlorite solution, you urgently need to wash them under running water for 20 minutes; if drops of the solution get into your eyes, you must immediately rinse them with plenty of water and transport the victim to a doctor.

Storage of sodium hypochlorite. Sodium hypochlorite should be stored in an unheated, ventilated warehouse. Do not store with organic products, flammable material or acid. Do not allow heavy metal salts into sodium hypochlorite or contact with such metals. This product packaged and transported in polyethylene containers (container, barrel, canister) or titanium containers and tank containers. The sodium hypochlorite product is not stable and does not have a guaranteed shelf life (note to GOST 11086-76).

8.2. Ozonation of water

Ozonation of water is used in the disinfection of drinking water, swimming pool water, wastewater, etc., allowing simultaneously to achieve discoloration, oxidation of iron and manganese, elimination of taste and odor of water and disinfection due to the very high oxidizing ability of ozone.

Ozone - a bluish or pale violet gas that spontaneously dissociates in air and in aqueous solution, turning into oxygen. The rate of ozone decay increases sharply in an alkaline environment and with increasing temperature. It has a high oxidizing capacity and destroys many organic substances present in natural and wastewater; is poorly soluble in water and quickly self-destructs; Being a powerful oxidizing agent, it can increase corrosion of pipelines with prolonged exposure.

It is necessary to take into account some features of ozonation. First of all, you need to remember about the rapid destruction of ozone, that is, the absence of such a long-term effect as chlorine.

Ozonation can cause (especially in highly colored waters and waters with a large amount of organic matter) the formation of additional sediments, so after ozonation it is necessary to provide for filtering the water through activated carbon. As a result of ozonation, by-products are formed including: aldehydes, ketones, organic acids, bromates (in the presence of bromides), peroxides and other compounds. When exposed to humic acids, where there are aromatic compounds of the phenolic type, phenol may appear. Some substances are ozone resistant. This disadvantage is overcome by introducing hydrogen peroxide into the water using the technology of the Degremont company (France) in a three-chamber reactor.

8.3. Ultraviolet water disinfection

Ultraviolet is called electromagnetic radiation within the wavelength range from 10 to 400 nm.

For disinfection, the “near region” is used: 200-400 nm (the wavelength of natural ultraviolet radiation at the earth’s surface is greater than 290 nm). Electromagnetic radiation at a wavelength of 200-315 nm has the greatest bactericidal effect. Modern UV devices use radiation with a wavelength of 253.7 nm.

The bactericidal effect of ultraviolet rays is explained by the photochemical reactions occurring under their influence in the structure of the DNA and RNA molecules, which constitute the universal information basis of the mechanism of reproducibility of living organisms.

The result of these reactions is irreversible damage to DNA and RNA. In addition, the action of ultraviolet radiation causes disturbances in the structure of membranes and cell walls of microorganisms. All this ultimately leads to their death.

The UV sterilizer is a metal case with a bactericidal lamp inside. This, in turn, is placed in a protective quartz tube. Water washes the quartz tube, is treated with ultraviolet light and, accordingly, is disinfected. There can be several lamps in one installation. The degree of inactivation or the proportion of microorganisms killed under the influence of UV radiation is proportional to the radiation intensity and exposure time. Accordingly, the number of neutralized (inactivated) microorganisms grows exponentially with increasing radiation dose. Due to the varying resistance of microorganisms, the dose of ultraviolet light required for inactivation, for example 99.9%, varies greatly from low doses for bacteria to very high doses for spores and protozoa. When passing through water, UV radiation is attenuated due to absorption and scattering effects. To take this weakening into account, a water absorption coefficient is introduced, the value of which depends on the quality of the water, especially on the content of iron, manganese, phenol in it, as well as on the turbidity of the water.

turbidity - no more than 2 mg/l (font transparency ≥30 degrees);

color - no more than 20 degrees of the platinum-cobalt scale;

UV installations); coli index - no more than 10,000 pcs/l.

For operational sanitary and technological control of the effectiveness and reliability of water disinfection with ultraviolet light, as with chlorination and ozonation, the determination of Escherichia coli bacteria (coliforms) is used.

Experience in the use of ultraviolet radiation shows: if the radiation dose in the installation is not lower than a certain value, then a stable disinfection effect is guaranteed. In world practice, the requirements for the minimum radiation dose vary from 16 to 40 mJ/cm2. The minimum dose corresponding to Russian standards is 16 mJ/cm2.

Advantages of the method:

The least “artificial” is ultraviolet rays;

The versatility and effectiveness of defeating various microorganisms - UV rays

destroy not only vegetative, but also spore-forming bacteria, which when

chlorination with usual standard doses of chlorine remain viable;

The physical and chemical composition of the treated water is preserved;

No upper dose limit;

There is no need to organize a special safety system, as with chlorination and

ozonation;

There are no secondary products;

There is no need to create a reagent facility;

The equipment operates without special maintenance personnel.

Disadvantages of the method:

A decrease in efficiency when treating poorly purified water (turbid, colored water is poorly

translucent);

Periodic cleaning of lamps from sediment deposits, required when processing turbid and

hard water;

There is no “aftereffect”, that is, the possibility of a secondary effect (after radiation treatment)

water contamination.

8.4. Comparison of the main methods of water disinfection

The basic methods of water disinfection described above have a wide variety of advantages and disadvantages, set out in numerous publications on this topic. Let us note the most significant of them.

Each of the three technologies, if used in accordance with the standards, can provide the necessary degree of bacterial inactivation, in particular, for indicator bacteria of the E. coli group and the total microbial number.

In relation to cysts of pathogenic protozoa, none of the methods provides a high degree of purification. To remove these microorganisms, it is recommended to combine disinfection processes with turbidity reduction processes.

The technological simplicity of the chlorination process and the non-scarcity of chlorine determine the widespread use of this particular disinfection method.

The ozonation method is the most technically complex and expensive compared to chlorination and ultraviolet disinfection.

Ultraviolet radiation does not change the chemical composition of water even at doses much higher than practically necessary.

Chlorination can lead to the formation of undesirable organochlorine compounds that are highly toxic and carcinogenic.

During ozonation, it is also possible to form by-products classified by regulations as toxic - aldehydes, ketones and other aliphatic aromatic compounds.

Ultraviolet radiation kills microorganisms, but ≪ the resulting fragments (cell walls of bacteria, fungi, protein fragments of viruses) remain in the water. Therefore, subsequent fine filtration is recommended.

. Chlorination only provides an aftereffect, that is, it has the necessary long-term effect, which makes the use of this method mandatory when supplying clean water to the water supply network.

9. Electrochemical methods

Electrochemical methods are widely used when traditional methods of mechanical, biological and physicochemical water treatment are not effective enough or cannot be used, for example, due to a lack of production space, the complexity of the delivery and use of reagents, or for other reasons. Installations for implementing these methods are compact, highly productive, and control and monitoring processes are relatively easily automated. Usually electrochemical processing used in combination with other purification methods, making it possible to successfully purify natural waters from impurities of various compositions and dispersion.

Electrochemical methods can be used to adjust the physical and chemical properties of the treated water; they have a high bactericidal effect and significantly simplify the technological purification schemes. In many cases, electrochemical methods eliminate secondary contamination of water with anionic and cationic residues characteristic of reagent methods.

Electrochemical water purification is based on electrolysis, the essence of which is the use of electrical energy to carry out oxidation and reduction processes. The electrolysis process occurs on the surface of electrodes located in an electrically conductive solution - an electrolyte.

The electrolysis process requires: an electrolyte solution - contaminated water, in which ions are always present in one concentration or another, ensuring the electrical conductivity of the water; electrodes immersed in an electrolyte solution; external current source; current leads - metal conductors connecting electrodes to a current source. Water itself is a poor conductor, but the charged ions in solution, formed during the dissociation of the electrolyte, under the influence of voltage applied to the electrodes, move in two opposite directions: positive ions (cations) to the cathode, negative ions (anions) to the anode. Anions give up their “extra” electrons to the anode, turning into neutral atoms. At the same time, the cations, reaching the cathode, receive the missing electrons from it and also become neutral atoms or a group of atoms (molecules). In this case, the number of electrons received by the anode is equal to the number of electrons transferred by the cathode. A constant electric current flows in the circuit. Thus, during electrolysis, redox processes occur: at the anode - loss of electrons (oxidation), at the cathode - acquisition of electrons (reduction). However, the mechanism of electrochemical reactions differs significantly from conventional chemical transformations of substances. A distinctive feature of an electrochemical reaction is the spatial separation of electrochemical reactions into two coupled processes: the processes of decomposition of substances or the production of new products occur at the electrode-solution boundary using an electric current. When electrolysis is carried out, simultaneously with electrode reactions in the volume of the solution, a change in the pH and redox potential of the system occurs, as well as phase-dispersed transformations of water impurities.

www. aqua-term. ru

The readiness of thermal power plants and boiler houses for winter, as part of the all-Russian program of preparation for the heating season, is attracting increased attention. The need to carry out work to ensure trouble-free operation of thermal equipment comes to the fore. One of the main problems that operating organizations face is the formation of solid deposits on the inner surface of boilers, heat exchangers and pipelines of thermal stations. The formation of these deposits leads to serious energy losses. These losses can reach 60%. The growth of deposits significantly reduces heat transfer. Large deposits can completely block the operation of the system, lead to clogging, accelerate corrosion and ultimately destroy expensive equipment.

All these problems arise due to the fact that, as a rule, there are either no boiler installations for recharging heating networks, or those that are installed are already morally and physically outdated. Source water is often supplied to the heating system without the necessary treatment and preparation.

At the same time, the reliability and efficiency of operation of boiler, heat and power and other similar equipment largely depends on the efficiency of water treatment. The extreme deterioration of the equipment of many boiler houses is often due to the fact that the latter was carried out a very, very long time ago.

How economically justified is it to spend on water treatment?

Experts have calculated that water treatment measures provide fuel savings of 20 to 40%, increase the life of boilers and boiler equipment to 25-30 years, and significantly reduce capital and operating costs in general, as well as individual elements, boilers and heating equipment. The payback period for water treatment plants depends on their productivity and ranges from 6 months to 1.5 - 2 years.

A significant number of facilities where modern water treatment systems of various capacities and purposes are installed, and the increased interest of operational services in this problem allows us to assert that the people on whom the heat in our homes depends have realized that the use of water treatment plants created on the basis of modern technologies and constructive solutions are the key to reliable, uninterrupted, trouble-free operation of both small boiler houses and large power units.

Krasnov M.S., Ph.D., process engineer at Ecodar company

Every person who works with water knows that today the main problem that everyone faces is increased water hardness. Because of it, you have to face a huge number of problems that have to be solved, here and now, without putting it off for a long time. is intended to result in a state permitted by law for use in food and drink, or for use in production with special requirements.

What's wrong with hard water that you have to constantly take care of it? I think everyone knows about scale. But it’s unlikely that everyone fully understands what its harm is. But besides scale and its poor heat conductivity, there is also increased water hardness, which has its consequences even before scale forms.

You will know that you are working with hard water by a large number of signs. However, if you are comfortable and easy to remove scale with your hands or with the help of descalers, you can continue, you just need to understand what you are risking by choosing this path to combat water hardness.

The first thing that is negatively affected by hard water is our health. Hardness salts are deposited everywhere. Whether it’s the walls of a household appliance or whether it’s the stomach or kidneys, they don’t care. Therefore, by the time you descale it, it has already formed in your body. Chronic diseases are not only rooted in poor lifestyle choices, but water quality also plays a role. which promising water treatment technologies do we know today?

In addition to being harmful to health, increased water hardness leaves its mark on our clothes, and here, too, descaling will not help at all. When we wash in hard water, we have to use more water and add half as much powder. What happens next? Due to the poor solubility of detergents in such water, the powder settles together with hardness salts inside the pores of the fabrics. To properly wash such a fabric, you will have to rinse it much longer. This is additional water consumption. We don’t notice all this, because... We constantly work with such expenses, and only application will help you see the difference.

However, today there is an opinion that any water filter is quite expensive, and its use in an apartment is not justified. And what is easier to remove scale. Two spheres that are indifferent to such removal are indicated from above. Things with white stains look unattractive and quickly become unusable. Much sooner than if you used water treatment technology and washed in soft water.

In addition, scale has such a big drawback as poor thermal conductivity. After all, why do you always need to monitor the size of scale on surfaces? so as not to be left without industrial equipment or without household appliances.

When scale covers heating elements or hot water surfaces, heat transfer to the water stops almost completely. At first, limescale at least somehow allows heat to pass through, but there is also such a nuance as a sharp increase fuel or electricity costs. It becomes much more difficult to heat the surface. That’s why so much fuel is wasted, and the thicker the layer of scale, the higher the costs.

The problem of scale is not only increased fuel consumption. A device with scale will begin to turn off over time, trying to protect itself from overheating. These are all signals that need to be responded to immediately. In this case, descaling should take place instantly. If this is not done, the scale will quickly turn into the limestone stage. Removing such cover is much more difficult. This time. This is money. And finally, there is the risk of losing the device. If you miss the moment, then the heat will have nowhere else to go, and it will simply rupture the heating element or surface. It is for this reason that you need to know all water treatment technologies perfectly!

In everyday life, this results in burnout of household appliances. Sometimes with a break in the wiring. In industry, this manifests itself in the form of fistulas on pipes and explosions of boilers in thermal power engineering.

Here is a set of reasons that encourage you to think about. With the help of a simple set of water filters, you can protect yourself and your family from the harmful effects of increased water hardness. When choosing one or another water treatment technology, you should remember that it can be done at the enterprise or in own home, an apartment will definitely not be possible with just a water softener.

Remember that when purifying water, you will always be faced with two tasks. You need drinking water and water for domestic needs. Therefore, the minimum water treatment that can only be in an apartment will consist of water purification using, for example, an electromagnetic water softener Aquashield. This will be for water for technical and domestic needs. And water purification using a filter jug, minimum or reverse osmosis, maximum. This is already for drinking needs. Then the protection against scale and hard water will be more or less reliable.

Now let's move directly to water treatment technologies. When choosing a particular technology, you need to know what problems it should solve. How do you know what to choose? Where to get the initial data to determine the type of water treatment technology and the sequence of water filters?

The very first thing you should do before choosing a promising water treatment technology is to conduct a chemical analysis of the water. Based on it, you can always calculate the volume of water entering the apartment and can clearly see its composition, all the impurities that will have to be removed. Having these results in hand, it will be easier for you to understand which water treatment technology is best to use, which sequence of filters to choose and what power this or that device should have.

Even if you take water from a central water purification system, it will still be hard. And here it is better not to save money, but to conduct a chemical analysis of the water. Then you will not overpay for a water softener that is too powerful and expensive.

All options for water treatment technologies can be found in the following list:

mechanical water purification;
chemical water purification;
disinfection;
microcleaning.

Chemical water purification refers to the removal of any organic impurities, nitrates, iron, and residual chlorine. Micropurification is the production of distillate or clean and healthy drinking water.

Let's take a closer look at the options for water filters that work using one or another water treatment technology.

So, mechanical water treatment technology. Its task is to remove all mechanical solid impurities, as well as calloids, from water. Here, water purification can take place in several stages. It starts with a rough cleaning. The water can even settle so that the largest mechanical impurities can settle. Sedimentary and gravel mesh can be used here.

Mesh filters include several meshes with different throughputs. They are used to filter both larger and smaller solids. The main material for the production of meshes is stainless steel. Such filters are installed first during the initial water intake.

Sediment filters are designed to remove very small particles that are invisible to the naked eye. Here the filter base is quartz sand and gravel. Sometimes hydroanthracite can be used. Such filters are used more for repeated water purification. This is how wastewater is purified or process water is prepared in production.

Cartridge filters are something between mechanical filtration and water softening. The only point is that such filters eliminate very small impurities measuring 150-1 microns. Such filters are installed for pre-cleaning in the same reverse osmosis.

Chemical water purification is rather an interesting and promising water treatment technology designed to correct chemical composition water, and not changes in its condition. This is through ion exchange, as well as deferrization. At this stage of water treatment, residual chlorine is removed from the water.

Manganese zeolite can be used for iron removal. This is green sand, which has excellent contact with ferrous compounds, efficiently filtering them from the water. In order for the reaction of iron retention in the filter to proceed even better, it would be nice if there were small inclusions of silicon in the water.

Another option for water treatment technology is the use of iron oxidation to purify water from its impurities. This is a reagent-free process and for this purpose special filters are used, where the water is blown with oxygen and under this influence the iron settles on the internal cartridge.

Ion exchange water filters are used to soften water. This is one of the most common water treatment technologies, both in everyday life and in production. The basis of such a filter is a resin cartridge. It is oversaturated with weak sodium, which is easy to replace in the structure of the substance. When contact with hard water occurs, hardness salts easily replace weak sodium. This is exactly what happens. Gradually, the cartridge completely gives up its sodium and becomes clogged with hardness salts.

In industry, such installations are one of the most popular, but also the most cumbersome. These are huge tanks in height. But they have the highest speed of water purification. At the same time, clogged cartridges are restored in industry and replaced in everyday life. The ion exchange filter is a reagent softener, so it could not be used for the production of drinking water until they came up with the idea of making the cartridge replaceable.

Such a cartridge is restored using a strong saline solution. The cartridge is changed at home. Because of this, the cost of using such water treatment technology increases. Although the installation itself is inexpensive, constantly changing cartridges is a constant expense. Moreover, it will also have to be changed quite often. In industry, expenses will also go towards salt. Although it is cheap, large volumes are expensive. Plus you will have to buy it constantly. And there is another problem with such an ion exchange apparatus in industry - after recovery, very harmful waste is generated. It is absolutely forbidden to dump such things into the atmosphere. Only with permission and after additional cleaning. This is again an expense. But in comparison with the cost of the same reverse osmosis, these costs are considered insignificant in industry.

New and modern water treatment technologies

For everyday use, those who want to save money on new and modern water treatment technologies can buy such a filter jug. True, installing reverse osmosis will pay for itself faster than such a filter with constant costs.

In order to remove turbidity and residual chlorine from water, activated carbon is used as a filter medium, which is the basis of a sorption filter.

For disinfection, ozonizers or ultraviolet water filters can be used. Here, the main task of new and modern water treatment technologies is to eliminate any bacteria and viruses. Ozonizers are most used in swimming pools, because... They are quite expensive, but at the same time environmentally friendly. Ultraviolet filters are reagent-free units and irradiate the water using an ultraviolet lamp, which kills any bacteria.

Another extremely popular technology today is electromagnetic water softening. A classic example of this. Most often, such new and modern water treatment technology is widely used in thermal power engineering. Installation at home is also popular. The basis here is permanent magnets and an electrical processor. Using the power of magnets, it generates electromagnetic waves that affect water. Under this influence, hardness salts are modified.

Having found new uniform, they do not have the ability to stick to surfaces. The thin needle-like surface allows only rubbing against old scale. This is where the second positive effect occurs. New hardness salts eliminate old ones. And they do it efficiently. When you install an Aquashield electromagnetic water softener, in a month you can safely spin up your boiler and see how it worked. I assure you, you will be pleased with the results. In this case, the device does not need to be serviced. Easy to install, easy to remove, works on its own, no need to replace filters or wash. You just need to place it on a clean piece of pipe. This is the only requirement.

And finally, new and modern water treatment technology, designed to produce high quality distillate and drinking water. These are nanofiltration and reverse osmosis. These are all technologies for fine water purification. Here, water is purified at the molecular level through a dispersion membrane with a huge number of holes no larger than a water molecule. Untreated water cannot be supplied to such an installation. Only after preliminary purification can water be purified by reverse osmosis. Because of this, any nanofiltration or osmosis installation will be expensive. And the materials for a thin membrane are quite expensive. But the quality of water purification here is the highest.

Thus, we have analyzed all the most popular and used new and modern water treatment technologies. Now you will understand what and how it works. With such knowledge, creating the right water purification system will not be difficult.