How to improve the quality of drinking water. Proposals for increasing the efficiency of water treatment when preparing water treatment plants to meet the requirements of SanPiN "Drinking water. Hygienic requirements for water quality of centralized drinking water supply systems

The composition of water can be different. After all, on the way to our home she encounters many obstacles. There are various methods for improving water quality, the general goal of which is to get rid of dangerous bacteria, humic compounds, excess salt, toxic substances, etc.

Water is the main component of the human body. It is one of the most important links in energy information exchange. Scientists have proven that thanks to the special network structure of water, which is created by hydrogen bonds, information is received, accumulated and transmitted.

The aging of the body and the volume of water in it are directly related to each other. Therefore, water should be consumed every day, making sure that it is of high quality.

Water is a powerful natural solvent, therefore, when it encounters different rocks on its way, it quickly becomes enriched with them. However, not all elements found in water are beneficial to humans. Some of them negatively affect the processes occurring in the human body, others can cause various diseases. In order to protect consumers from harmful and dangerous impurities, measures are being taken to improve the quality of drinking water.

Ways to improve

There are basic and special methods for improving the quality of drinking water. The first involves lightening, disinfection and bleaching, the second involves procedures for defluoridation, iron removal and desalting.

Decolorization and clarification remove colored colloids and suspended particles from water. The purpose of the disinfection procedure is to eliminate bacteria, infections and viruses. Special methods - mineralization and fluoridation - involve the introduction of substances necessary for the body into the water.

The nature of the contamination determines the use of the following cleaning methods:

Mechanical – involves removing impurities using sieves, filters and gratings of coarse impurities.
Physical – involves boiling, UV and irradiation with γ-rays.
Chemical, in which reagents are added to wastewater, which provoke the formation of sediments. Today, the main method of disinfecting drinking water is chlorination. Tap water, according to SanPiN, must contain a residual chlorine concentration of 0.3-0.5 mg/l.
Biological treatment requires special irrigation or filtration fields. A network of canals is formed that are filled with wastewater. After purification by air, sunlight and microorganisms, they seep into the soil, forming humus on the surface.

For biological treatment, which can also be carried out in artificial conditions, there are special structures - biofilters and aeration tanks. A biofilter is a brick or concrete structure, inside of which there is a porous material - gravel, slag or crushed stone. They are coated with microorganisms that purify water as a result of their vital activity.

In aeration tanks, with the help of incoming air, activated sludge moves in wastewater. Secondary settling tanks are designed to separate bacterial film from purified water. The destruction of pathogenic microorganisms in domestic waters is carried out using chlorine disinfection.

To assess the quality of water, you need to determine the amount of harmful substances that ended up there after treatment (chlorine, aluminum, polyacrylamide, etc.) and anthropogenic substances (nitrates, copper, petroleum products, manganese, phenols, etc.). Organoleptic and radiation indicators should also be taken into account.

How to improve water quality at home

To improve the quality of tap water at home, additional purification is required, for which household filters are used. Today, manufacturers offer them in huge quantities.

One of the most popular are filters whose operation is based on reverse osmosis.

They are actively used not only at home, but also in catering establishments, hospitals, sanatoriums, and manufacturing enterprises.

The filtration system has an auto-flush that must be turned on before filtration begins. Through the polyamide membrane through which water passes, it is freed from contaminants - cleaning is carried out at the molecular level. Such installations are ergonomic and compact, and the quality of filtered water is very high.

Water Purification: Video

Water is the main component of the liquid medium of the human body. The adult human body is 60% water.

Nowadays tap water contains chemical organic and other compounds and cannot be considered drinking water without preliminary treatment.

To improve the quality of drinking water, the following purification methods can be proposed:

1. Neutralization method. Pour water from the tap into a container (glass or enamel). Leave the container open for 24 hours. During this time, chlorine, ammonia and other gaseous substances will come out of the water. Then boil it for one hour. From the moment of boiling, achieve only a slight bubbling. As a result of heat treatment, a significant part of foreign substances is eliminated. After cooling, the water has not yet been completely freed from chemical and organic substances, but it can already be used for cooking. For drinking purposes, it must be completely neutralized; to do this, add 500 mg of ascorbic acid to 5 liters of boiled water, 300 mg to 3 liters, mix and leave for one hour. Instead of ascorbic acid, you can add fruit juice, colored red, dark red, burgundy to a light pinkish tint, and leave for one hour. To neutralize, you can use drunk tea, which is added to the water until the color changes slightly, and left for one hour.

2. Freezing method. For this, milk and juice bags can be used, into which tap water is poured, adding 1 - 1.5 cm to the edge. The bags filled with water should be placed in the freezer or in the cold for 5 - 8 hours, after which take out the bags, remove the ice crust, pour the water into another bag. Ice crust and ice frozen on the inside of the bag is heavy (harmful) water. Water poured into bags is frozen for 12 to 18 hours. Then the bags are taken out, the outer walls are moistened with warm water, the ice crystals are removed to thaw, and the liquid remaining in the bags is nothing more than a brine consisting of foreign and mineral substances, which must be poured down the drain.

If your bags are frozen and a solid crystal with a middle rod has formed, then, without removing it from the bag, wash the rod with warm water, leaving clear ice, then remove the ice to thaw. To improve the taste, add 1 g of sea salt (purchased at a pharmacy) to a bucket of melt water. If it is absent, add 1/4 - 1/5 cup of mineral water to 1 liter of melt water. Freshly melted water obtained from ice, or better yet from snow, has therapeutic and prophylactic properties. When consumed, recovery processes are accelerated. Such water promotes adaptation in extreme conditions (under thermal stress, with reduced oxygen content in the air), it significantly increases muscle performance. Melt water has anti-allergic properties and is used, for example, for bronchial asthma, itchy dermatitis of an allergic nature, and stomatitis. However, this water should be used with caution and should be taken 1/2 glass 3 times a day for an adult. For a child 10 years old - 1/4 cup 3 times a day

Z. I. Khata - M.: FAIR PRESS, 2001

Water is an integral part of our life. We drink a certain amount every day and often don’t even think about the fact that water disinfection and its quality are an important topic. But in vain, heavy metals, chemical compounds and pathogenic bacteria can cause irreversible changes in the human body. Today, serious attention is paid to water hygiene. Modern methods of disinfecting drinking water can clean it of bacteria, fungi, and viruses. They will also come to the rescue if the water smells bad, has foreign tastes, or is colored.

Preferred methods for improving quality are selected depending on the microorganisms contained in the water, the level of contamination, the source of the water supply and other factors. Disinfection is aimed at removing pathogenic bacteria that have a destructive effect on the human body.

Purified water is transparent, has no foreign tastes or odors, and is absolutely safe. In practice, methods of two groups, as well as their combination, are used to combat harmful microorganisms:

chemical;
physical;
combined.

In order to select effective disinfection methods, it is necessary to analyze the liquid. Among the analyzes performed are:

chemical;
bacteriological;

The use of chemical analysis makes it possible to determine the content of various chemical elements in water: nitrates, sulfates, chlorides, fluorides, etc. Nevertheless, the indicators analyzed by this method can be divided into 4 groups:

Organoleptic indicators. Chemical analysis of water allows you to determine its taste, smell and color.
Integral indicators – density, acidity and water hardness.
Inorganic – various metals contained in water.
Organic indicators are the content of substances in water that can change under the influence of oxidizing agents.

Bacteriological analysis is aimed at identifying various microorganisms: bacteria, viruses, fungi. Such an analysis reveals the source of contamination and helps determine disinfection methods.

Chemical methods for disinfecting drinking water

Chemical methods are based on adding various oxidizing reagents to water that kill harmful bacteria. The most popular among such substances are chlorine, ozone, sodium hypochlorite, and chlorine dioxide.

To achieve high quality, it is important to correctly calculate the dose of the reagent. A small amount of a substance may have no effect, and even, on the contrary, contribute to an increase in the number of bacteria. The reagent must be administered in excess, this will destroy both existing microorganisms and bacteria that have entered the water after disinfection.

The excess must be calculated very carefully so that it cannot harm people. The most popular chemical methods:

chlorination;
ozonation;
oligodynamy;
polymer reagents;
iodination;
bromination.

Chlorination

Water purification by chlorination is traditional and one of the most popular methods of water purification. Chlorine-containing substances are actively used to purify drinking water, water in swimming pools, and disinfect premises.

This method has gained popularity due to its ease of use, low cost, and high efficiency. Most pathogenic microorganisms that cause various diseases are not resistant to chlorine, which has a bactericidal effect.

To create unfavorable conditions that prevent the proliferation and development of microorganisms, it is enough to introduce chlorine in a slight excess. Excess chlorine helps prolong the disinfection effect.

During water treatment, the following chlorination methods are possible: preliminary and final. Pre-chlorination is used as close as possible to the point of water intake; at this stage, the use of chlorine not only disinfects the water, but also helps remove a number of chemical elements, including iron and manganese. Final chlorination is the last stage in the treatment process, during which harmful microorganisms are destroyed through chlorine.

There is also a distinction between normal chlorination and overchlorination. Normal chlorination is used to disinfect liquids from sources with good sanitary characteristics. Overchlorination - in case of severe contamination of water, as well as if it is contaminated with phenols, which in the case of normal chlorination only worsen the condition of the water. In this case, the remaining chlorine is removed by dechlorination.

Chlorination, like other methods, along with its advantages, also has its disadvantages. When chlorine enters the human body in excess, it leads to problems with the kidneys, liver, and gastrointestinal tract. The high corrosiveness of chlorine leads to rapid wear of equipment. The chlorination process produces all sorts of byproducts. For example, trihalomethanes (chlorine compounds with substances of organic origin) can cause asthma symptoms.

Due to the widespread use of chlorination, a number of microorganisms have developed resistance to chlorine, so a certain percentage of water contamination is still possible.

The most commonly used water disinfectants are chlorine gas, bleach, chlorine dioxide, and sodium hypochlorite.

Chlorine is the most popular reagent. It is used in liquid and gaseous form. By destroying pathogenic microflora, it eliminates unpleasant taste and smell. Prevents the growth of algae and leads to improved fluid quality.

For purification with chlorine, chlorinators are used, in which chlorine gas is absorbed with water, and then the resulting liquid is delivered to the place of use. Despite the popularity of this method, it is quite dangerous. Transportation and storage of highly toxic chlorine requires compliance with safety precautions.

Chloride of lime is a substance produced by the action of chlorine gas on dry slaked lime. To disinfect liquids, bleach is used, the percentage of chlorine in which is at least 32-35%. This reagent is very dangerous for humans and causes difficulties in production. Due to these and other factors, bleach is losing its popularity.

Chlorine dioxide has a bactericidal effect and practically does not pollute water. Unlike chlorine, it does not form trihalomethanes. The main reason that hinders its use is its high explosion hazard, which complicates production, transportation and storage. Currently, on-site production technology has been mastered. Destroys all types of microorganisms. To the disadvantages This may include the ability to form secondary compounds – chlorates and chlorites.

Sodium hypochlorite is used in liquid form. The percentage of active chlorine in it is twice as high as in bleach. Unlike titanium dioxide, it is relatively safe during storage and use. A number of bacteria are resistant to its effects. In case of long-term storage, it loses its properties. It is available on the market in the form of a liquid solution with varying chlorine content.

It is worth noting that all chlorine-containing reagents are highly corrosive, and therefore they are not recommended for use to purify water entering water through metal pipelines.

Ozonation

Ozone, like chlorine, is a strong oxidizing agent. Penetrating through the membranes of microorganisms, it destroys the cell walls and kills it. both with water disinfection and with its decolorization and deodorization. Capable of oxidizing iron and manganese.

Possessing a high antiseptic effect, ozone destroys harmful microorganisms hundreds of times faster than other reagents. Unlike chlorine, it destroys almost all known types of microorganisms.

When decomposed, the reagent is converted into oxygen, which saturates the human body at the cellular level. The rapid decay of ozone at the same time is also a disadvantage of this method, since after 15-20 minutes. after the procedure, the water may become re-contaminated. There is a theory according to which, when water is exposed to ozone, the phenolic groups of humic substances begin to decompose. They activate organisms that were dormant until the moment of treatment.

When water is saturated with ozone, it becomes corrosive. This leads to damage to water pipes, plumbing fixtures, and household appliances. In the case of an erroneous amount of ozone, the formation of by-products that are highly toxic may occur.

Ozonation has other disadvantages, which include the high cost of purchase and installation, high electrical costs, as well as a high ozone hazard class. When working with the reagent, care and safety precautions must be observed.

Ozonation of water is possible using a system consisting of:

an ozone generator in which the process of separating ozone from oxygen occurs;
a system that allows you to introduce ozone into water and mix it with the liquid;
reactor - a container in which ozone interacts with water;
destructor - a device that removes residual ozone, as well as devices that control ozone in water and air.

Oligodynamy

Oligodynamy is the disinfection of water through exposure to noble metals. The most studied uses of gold, silver and copper.

The most popular metal for the purpose of destroying harmful microorganisms is silver. Its properties were discovered in ancient times; a spoon or a silver coin was placed in a container of water and the water was allowed to settle. The assertion that this method is effective is quite controversial.

Theories about the influence of silver on microbes have not received final confirmation. There is a hypothesis according to which the cell is destroyed by electrostatic forces arising between silver ions with a positive charge and negatively charged bacterial cells.

Silver is a heavy metal that, if accumulated in the body, can cause a number of diseases. An antiseptic effect can be achieved only with high concentrations of this metal, which is harmful to the body. A smaller amount of silver can only stop the growth of bacteria.

In addition, spore-forming bacteria are practically insensitive to silver; its effect on viruses has not been proven. Therefore, the use of silver is advisable only to extend the shelf life of initially pure water.

Another heavy metal that can have a bactericidal effect is copper. Even in ancient times, it was noticed that water that stood in copper vessels retained its high substances much longer. In practice, this method is used in basic domestic conditions to purify a small volume of water.

Polymer reagents

The use of polymer reagents is a modern method of water disinfection. It significantly outperforms chlorination and ozonation due to its safety. Liquid purified with polymer antiseptics has no taste or foreign odors, does not cause metal corrosion, and does not affect the human body. This method has become widespread in water purification in swimming pools. Water purified with a polymer reagent has no color, foreign taste or smell.

Iodination and bromination

Iodination is a disinfection method that uses iodine-containing compounds. The disinfecting properties of iodine have been known to medicine since ancient times. Despite the fact that this method is widely known and attempts have been made to use it several times, the use of iodine as a water disinfectant has not gained popularity. This method has a significant drawback: dissolving in water, it causes a specific odor.

Bromine is a fairly effective reagent that destroys most known bacteria. However, due to its high cost, it is not popular.

Physical methods of water disinfection

Physical methods of purification and disinfection work on water without the use of reagents or interference with the chemical composition. The most popular physical methods:

UV irradiation;
ultrasonic influence;
heat treatment;
electric pulse method;

UV radiation

The use of UV radiation is gaining increasing popularity among water disinfection methods. The technique is based on the fact that rays with a wavelength of 200-295 nm can kill pathogenic microorganisms. Penetrating through the cell wall, they affect nucleic acids (RND and DNA), and also cause disturbances in the structure of membranes and cell walls of microorganisms, which leads to the death of bacteria.

To determine the radiation dose, it is necessary to conduct a bacteriological analysis of the water, this will identify the types of pathogenic microorganisms and their susceptibility to rays. Efficiency is also affected by the power of the lamp used and the level of radiation absorption by water.

The dose of UV radiation is equal to the product of the radiation intensity and its duration. The higher the resistance of microorganisms, the longer it is necessary to influence them

UV radiation does not affect the chemical composition of water, does not form side compounds, thus eliminating the possibility of harm to humans.

When using this method, an overdose is impossible; UV irradiation has a high reaction rate; it takes several seconds to disinfect the entire volume of liquid. Without changing the composition of water, radiation can destroy all known microorganisms.

However, this method is not without its drawbacks. Unlike chlorination, which has a prolonged effect, the effectiveness of irradiation remains as long as the rays affect the water.

A good result is achievable only in purified water. The level of ultraviolet absorption is affected by impurities contained in the water. For example, iron can serve as a kind of shield for bacteria and “hide” them from exposure to rays. Therefore, it is advisable to pre-purify the water.

The UV radiation system consists of several elements: a stainless steel chamber in which a lamp is placed, protected by quartz covers. Passing through the mechanism of such an installation, water is constantly exposed to ultraviolet radiation and completely disinfected.

Ultrasonic disinfection

Ultrasonic disinfection is based on the cavitation method. Due to the fact that sharp changes in pressure occur under the influence of ultrasound, microorganisms are destroyed. Ultrasound is also effective in combating algae.

This method has a narrow range of use and is at the development stage. The advantage is insensitivity to high turbidity and color of water, as well as the ability to influence most forms of microorganisms.

Unfortunately, this method is only applicable for small volumes of water. Like UV irradiation, it only has an effect when it interacts with water. Ultrasonic disinfection has not gained popularity due to the need to install complex and expensive equipment.

Thermal treatment of water

At home, the thermal method of purifying water is the well-known boiling. High temperature kills most microorganisms. In industrial conditions, this method is ineffective due to its bulkiness, time-consuming and low intensity. In addition, heat treatment is not able to get rid of foreign tastes and pathogenic spores.

Electropulse method

The electropulse method is based on the use of electrical discharges that form a shock wave. Under the influence of hydraulic shock, microorganisms die. This method is effective for both vegetative and spore-forming bacteria. Able to achieve results even in cloudy water. In addition, the bactericidal properties of treated water last up to four months.

The downside is high energy consumption and high cost.

Combined methods of water disinfection

To achieve the greatest effect, combined methods are used; as a rule, reagent methods are combined with non-reagent ones.

The combination of UV irradiation with chlorination has become very popular. Thus, UV rays kill pathogenic microflora, and chlorine prevents re-infection. This method is used both for drinking water purification and for purifying water in swimming pools.

To disinfect swimming pools, UV radiation is mainly used with sodium hypochlorite.

You can replace chlorination at the first stage with ozonation

Other methods include oxidation in combination with heavy metals. Both chlorine-containing elements and ozone can act as oxidizing agents. The essence of the combination is that oxidizing agents kill harmful microbes, and heavy metals help keep water disinfected. There are other methods of complex water disinfection.

Purification and disinfection of water in domestic conditions

It is often necessary to purify water in small quantities right here and now. For these purposes use:

soluble disinfectant tablets;
potassium permanganate;
silicon;
improvised flowers, herbs.

Disinfectant tablets can help out when traveling. As a rule, one tablet is used per 1 liter. water. This method can be classified as a chemical group. Most often, these tablets are based on active chlorine. The action time of the tablet is 15-20 minutes. In case of severe contamination, the amount can be doubled.

If suddenly there are no tablets, it is possible to use ordinary potassium permanganate at the rate of 1-2 g per bucket of water. After the water has settled, it is ready for use.

Natural plants also have a bactericidal effect - chamomile, celandine, St. John's wort, lingonberry.

Another reagent is silicon. Place it in water and let it sit for 24 hours.

Sources of water supply and their suitability for disinfection

Sources of water supply can be divided into two types - surface and groundwater. The first group includes water from rivers and lakes, seas and reservoirs.

When analyzing the suitability of drinking water located on the surface, bacteriological and chemical analysis is carried out, the condition of the bottom, temperature, density and salinity of sea water, radioactivity of water, etc. are assessed. An important role when choosing a source is played by the proximity of industrial facilities. Another stage in assessing the source of water intake is calculating the possible risks of water contamination.

The composition of water in open reservoirs depends on the time of year; such water contains various contaminants, including pathogens. The risk of contamination of water bodies near cities, plants, factories and other industrial facilities is highest.

River water is very turbid, characterized by color and hardness, as well as a large number of microorganisms, infection of which most often occurs from waste water. Blooms due to the development of algae are common in water from lakes and reservoirs. Also such waters

The peculiarity of surface sources is the large water surface that comes into contact with the sun's rays. On the one hand, this contributes to the self-purification of water, on the other hand, it serves the development of flora and fauna.

Despite the fact that surface waters can self-purify, this does not save them from mechanical impurities and pathogenic microflora, therefore, when water is collected, they undergo thorough purification with further disinfection.

Another type of water intake source is groundwater. The content of microorganisms in them is minimal. Spring and artesian water are best suited to supply the population. To determine their quality, experts analyze the hydrology of rock layers. Particular attention is paid to the sanitary condition of the territory in the area of water intake, since this affects not only the quality of water here and now, but also the prospect of infection by harmful microorganisms in the future.

Artesian and spring water is superior to water from rivers and lakes; it is protected from bacteria contained in waste water, from exposure to sunlight and other factors that contribute to the development of unfavorable microflora.

Regulatory documents of water and sanitary legislation

Since water is the source of human life, its quality and sanitary condition are given serious attention, including at the legislative level. The main documents in this area are the Water Code and the Federal Law “On the Sanitary and Epidemiological Welfare of the Population.”

The Water Code contains rules for the use and protection of water bodies. Provides a classification of groundwater and surface waters, determines penalties for violation of water legislation, etc.

The Federal Law “On the Sanitary and Epidemiological Welfare of the Population” regulates the requirements for sources from which water can be used for drinking and housekeeping.

There are also state quality standards that determine suitability indicators and put forward requirements for water analysis methods:

GOST water quality standards

GOST R 51232-98 Drinking water. General requirements for organization and methods of quality control.
GOST 24902-81 Water for domestic and drinking purposes. General requirements for field methods of analysis.
GOST 27064-86 Water quality. Terms and Definitions.
GOST 17.1.1.04-80 Classification of groundwater according to water use purposes.

SNiPs and water requirements

Building codes and regulations (SNiP) contain rules for organizing the internal water supply and sewerage systems of buildings, regulate the installation of water supply, heating systems, etc.

SNiP 2.04.01-85 Internal water supply and sewerage of buildings.
SNiP 3.05.01-85 Internal sanitary systems.
SNiP 3.05.04-85 External networks and structures of water supply and sewerage.

Sanitary standards for water supply

In the sanitary and epidemiological rules and regulations (SanPiN) you can find what requirements exist for the quality of water both from the central water supply and water from wells and boreholes.

SanPiN 2.1.4.559-96 “Drinking water. Hygienic requirements for water quality of centralized drinking water supply systems. Quality control."
SanPiN 4630-88 “MPC and TAC of harmful substances in water of water bodies for domestic, drinking and cultural water use”
SanPiN 2.1.4.544-96 Requirements for water quality of non-centralized water supply. Sanitary protection of sources.
SanPiN 2.2.1/2.1.1.984-00 Sanitary protection zones and sanitary classification of enterprises, structures and other objects.

Although the flood in the Moscow region after an abnormally snowy winter, as the authorities assured, passed without incident, and the reservoirs are ready for normal operation throughout the year, the quality of water in the Moscow region leaves much to be desired - according to regional authorities, 40% of the water in the water supply does not comply standards How residents can check the quality of the water that flows from their taps at home, independently and in the laboratory, what they need to remember when choosing a filter and what ways there are to improve the quality of water, the correspondent of “In the Moscow Region” found out.

Tea-colored water: risk factors

Drinking water is in fact a much more complex compound than the H2O formula known from chemistry lessons. It may contain a large number of different substances and impurities, and this does not always mean poor quality. The guidelines “Drinking water and water supply to populated areas” of the State System of Sanitary and Epidemiological Standards of the Russian Federation speak of the 68 substances most commonly contained in drinking water. For each of them there is a maximum permissible concentration (MAC), if deviated from, these substances can negatively affect the condition of tooth enamel and mucous membranes, as well as vital human organs: liver, kidneys, gastrointestinal tract and many others. Of course, if you drink a glass of unpurified water, the body will be able to cope with this “micro-poisoning”. But if you consume harmful amounts of substances daily, it can negatively affect your health.

The quality of drinking water is directly affected by human activities. According to the ecologist, head of the laboratory of the Department of Chemistry and Engineering Ecology at FBGOU MIIT, Maria Kovalenko, the main reasons for the deterioration in the quality of drinking water in the Moscow region are:

Development of zones located in a single ecosystem with artesian wells;

Worn-out water supply network: according to the regional housing and communal services construction complex, 36% of networks in the Moscow region are dilapidated, and 40% of water does not meet standards;

Poor condition of treatment facilities: for example, in the Yegoryevsky region, according to the Main Control Department (GKU) of the Moscow Region, treatment facilities in rural settlements are 80% worn out;

Negligent attitude towards industrial waste at many enterprises;

The cost of water analysis, depending on the number of studies required and the laboratory, can range from 1,200 to 3,000 rubles. According to employees of the laboratory of the Department of Chemistry and Engineering Ecology of FBGOU MIIT, the basic analysis of water from wells and water supply networks includes 30 main indicators, including aluminum, iron, manganese, nitrates, nitrites, chlorides, sulfides, etc.

You can also check the quality of the filter using laboratory analysis. To do this, you need to test the water before and after filtration and compare the results.

How to purify water at home: kettle, filter, silver spoons

Experts suggest improving the quality of drinking water at home in several ways. First you need to settle the water: pour water into a container and let it sit for a day, protecting it from dust with a lid.

1. Filtration. Pass the water through any filter containing carbon. This can be a filter jug with a replaceable cassette (average price 400 rubles), a nozzle for a faucet (costs approximately 200-700 rubles) and a filter for a riser (their installation will cost 2 thousand rubles and more). Each of them has its own advantages, but it is important to remember that the last two options will not suit all homes. For example, older buildings may have problems with reduced water pressure and worn-out pipes, so a filter is unlikely to help.

2. Boiling. To boil water, use a regular kettle, not an electric one: the water will boil more slowly, but there will be much less scale.

3. Cleansing with silver. Even an ordinary silver spoon dipped into a reservoir of water can improve its properties.

4. Water disinfection with ultraviolet light or ozonation. When water comes into contact with ozone and UV radiation, bacteria and viruses are destroyed. For this purpose, you can purchase special installations. Before choosing a specific filter for an apartment or an entire entrance, it is better for residents to consult with a specialist.

The Moscow region will be brought to "Clean Water"

It is obvious that the problem of water purification needs to be approached not only at the level of an individual apartment, but also on a regional scale. Since 2013, the Moscow region has been implementing a long-term target program “Clean Water in the Moscow Region”, which is designed for 2013-2020. It is aimed at improving the quality of drinking water, purifying wastewater to standard levels and reducing the risk to public health. The project is now being approved by the Ministry of Finance of the Moscow Region and the Tariff Committee, and it is possible that as early as next year there will be changes at the global level in the situation with poor-quality drinking water.

Svetlana KONDRATIEVA

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LECTURE No. 3. METHODS OF IMPROVING WATER QUALITY

The use of natural waters from open reservoirs, and sometimes groundwater, for domestic and drinking water supply purposes is practically impossible without first improving the properties of the water and its disinfection. To ensure that the quality of water meets hygienic requirements, pre-treatment is used, as a result of which the water is freed from suspended particles, odor, taste, microorganisms and various impurities.

To improve water quality, the following methods are used: 1) purification - removal of suspended particles; 2) disinfection - destruction of microorganisms; 3) special methods for improving the organoleptic properties of water, softening, removal of certain chemicals, fluoridation, etc.

Water purification. Purification is an important step in the overall set of methods for improving water quality, as it improves its physical and organoleptic properties. At the same time, in the process of removing suspended particles from water, a significant part of microorganisms is also removed, as a result of which complete water purification makes it easier and more economical to carry out disinfection. Cleaning is carried out by mechanical (settling), physical (filtration) and chemical (coagulation) methods.

Settling, during which clarification and partial discoloration of water occurs, is carried out in special structures - settling tanks. Two designs of settling tanks are used: horizontal and vertical. The principle of their operation is that, due to the flow of water through a narrow hole and the slow flow of water in the sump, the bulk of suspended particles settle to the bottom. The settling process in settling tanks of various designs continues for 2-8 hours. However, the smallest particles, including a significant part of microorganisms, do not have time to settle. Therefore, sedimentation cannot be considered as the main method of water purification.

Filtration is the process of more completely freeing water from suspended particles, which consists in passing water through a fine-porous filter material, most often through sand with a certain particle size. As water filters, it leaves suspended particles on the surface and in the depths of the filter material. At waterworks, filtration is used after coagulation.

Currently, quartz-anthracite filters have begun to be used, significantly increasing the filtration rate.

To pre-filtrate water, microfilters are used to capture zooplankton - the smallest aquatic animals and phytoplankton - the smallest aquatic plants. These filters are installed in front of the water intake point or in front of the treatment plant.

Coagulation is a chemical method of water purification. The advantage of this method is that it allows you to free water from contaminants that are in the form of suspended particles that cannot be removed by settling and filtration. The essence of coagulation is the addition of a coagulant chemical to water that can react with the bicarbonates in it. As a result of this reaction, large, rather heavy flakes are formed that carry a positive charge. As they settle due to their own gravity, they carry with them negatively charged pollutant particles suspended in the water, and thereby contribute to fairly rapid water purification. Due to this process, the water becomes transparent and the color index improves.

Aluminum sulfate is currently most widely used as a coagulant; it forms large flakes of aluminum oxide hydrate with water bicarbonates. To improve the coagulation process, high-molecular flocculants are used: alkaline starch, ionic flocculants, activated silicic acid and other synthetic preparations derived from acrylic acid, in particular polyacrylamide (PAA).

Disinfection. The destruction of microorganisms is the last final stage of water treatment, ensuring its epidemiological safety. Chemical (reagent) and physical (reagent-free) methods are used to disinfect water. In laboratory conditions, a mechanical method can be used for small volumes of water.

Chemical (reagent) disinfection methods are based on adding various chemicals to water, causing the death of microorganisms in the water. These methods are quite effective. Various strong oxidizing agents can be used as reagents: chlorine and its compounds, ozone, iodine, potassium permanganate, some salts of heavy metals, silver.

In sanitary practice, the most reliable and proven method of water disinfection is chlorination. At waterworks it is produced using chlorine gas and bleach solutions. In addition, chlorine compounds such as sodium hypochlorate, calcium hypochlorite, and chlorine dioxide can be used.

The mechanism of action of chlorine is that when it is added to water, it hydrolyzes, resulting in the formation of hydrochloric and hypochlorous acids:

C1 2 +H 2 O=HC1+HOC1.

Hypochlorous acid in water dissociates into hydrogen ions (H) and hypochlorite ions (OC1), which, along with dissociated hypochlorous acid molecules, have a bactericidal property. The complex (HOC1 + OC1) is called free active chlorine.

The bactericidal effect of chlorine is carried out mainly due to hypochlorous acid, the molecules of which are small, have a neutral charge and therefore easily pass through the bacterial cell membrane. Hypochlorous acid affects cellular enzymes, in particular SH groups, disrupts the metabolism of microbial cells and the ability of microorganisms to reproduce. In recent years, it has been established that the bactericidal effect of chlorine is based on the inhibition of enzyme catalysts and redox processes that ensure the energy metabolism of the bacterial cell.

The disinfecting effect of chlorine depends on many factors, among which the dominant ones are the biological characteristics of microorganisms, the activity of active chlorine preparations, the state of the aquatic environment and the conditions under which chlorination is carried out.

The chlorination process depends on the persistence of microorganisms. The most stable are the spore-forming ones. Among non-spores, the attitude towards chlorine is different, for example, the typhoid bacillus is less stable than the paratyphoid bacillus, etc. The massiveness of microbial contamination is important: the higher it is, the more chlorine is needed to disinfect water. The effectiveness of disinfection depends on the activity of the chlorine-containing preparations used. Thus, chlorine gas is more effective than bleach.

The composition of water has a great influence on the chlorination process; the process slows down in the presence of a large amount of organic substances, since more chlorine is spent on their oxidation, and at low water temperatures. An essential condition for chlorination is the correct choice of dose. The higher the dose of chlorine and the longer its contact with water, the higher the disinfecting effect will be.

Chlorination is carried out after water purification and is the final stage of its processing at a waterworks. Sometimes, to enhance the disinfecting effect and improve coagulation, part of the chlorine is introduced along with the coagulant, and the other part, as usual, after filtration. This method is called double chlorination.

A distinction is made between conventional chlorination, i.e. chlorination with normal doses of chlorine, which are established each time experimentally, and superchlorination, i.e. chlorination with increased doses.

Chlorination in normal doses is used under normal conditions at all waterworks. In this case, the correct choice of the dose of chlorine is of great importance, which determines the degree of chlorine absorption of water in each specific case.

To achieve a complete bactericidal effect, the optimal dose of chlorine is determined, which consists of the amount of active chlorine that is necessary for: a) destruction of microorganisms; b) oxidation of organic substances, as well as the amount of chlorine that must remain in the water after chlorination in order to serve as an indicator of the reliability of chlorination. This amount is called active residual chlorine. Its norm is 0.3-0.5 mg/l, with free chlorine 0.8-1.2 mg/l. The need to standardize these quantities is due to the fact that if the presence of residual chlorine is less than 0.3 mg/l, it may not be enough to disinfect water, and at doses above 0.5 mg/l, the water acquires an unpleasant specific smell of chlorine.

The main conditions for effective chlorination of water are mixing it with chlorine, contact between disinfection water and chlorine for 30 minutes in the warm season and 60 minutes in the cold season.

At large waterworks, chlorine gas is used to disinfect water. To do this, liquid chlorine, delivered to the water supply station in tanks or cylinders, is converted into a gaseous state before use in special chlorinator installations, which provide automatic supply and dosing of chlorine. The most common chlorination of water is a 1% solution of bleach. Bleach is a product of the interaction of chlorine and calcium oxide hydrate as a result of the reaction:

2Ca(OH) 2 + 2C1 2 = Ca(OC1) 2 + CaC1 2 + 2HA

Superchlorination (hyperchlorination) of water is carried out for epidemiological reasons or in conditions where it is impossible to ensure the necessary contact of water with chlorine (within 30 minutes). It is usually used in military field conditions, expeditions and other cases and is produced in doses 5-10 times higher than the chlorine absorption capacity of water, i.e. 10-20 mg/l of active chlorine. The contact time between water and chlorine is reduced to 15-10 minutes. Superchlorination has a number of advantages. The main ones are a significant reduction in the time of chlorination, simplification of its technique, since there is no need to determine the residual chlorine and dose, and the possibility of disinfecting water without first freeing it from turbidity and clarification. The disadvantage of hyperchlorination is the strong smell of chlorine, but this can be eliminated by adding sodium thiosulfate, activated carbon, sulfur dioxide and other substances to the water (dechlorination).

At waterworks, chlorination and preammonization are sometimes carried out. This method is used in cases where the water being disinfected contains phenol or other substances that give it an unpleasant odor. To do this, ammonia or its salts are first introduced into the water to be disinfected, and then chlorine after 1-2 minutes. This produces chloramines, which have strong bactericidal properties.

Chemical methods of water disinfection include ozonation. Ozone is an unstable compound. In water, it decomposes to form molecular and atomic oxygen, which is associated with the strong oxidizing ability of ozone. During its decomposition, free radicals OH and HO 2 are formed, which have pronounced oxidizing properties. Ozone has a high redox potential, so its reaction with organic substances in water is more complete than that of chlorine. The mechanism of the disinfecting action of ozone is similar to the action of chlorine: being a strong oxidizing agent, ozone damages the vital enzymes of microorganisms and causes their death. There are suggestions that it acts as a protoplasmic poison.

The advantage of ozonation over chlorination is that this disinfection method improves the taste and color of water, so ozone can be used at the same time to improve its organoleptic properties. Ozonation does not have a negative effect on the mineral composition and pH of water. Excess ozone is converted into oxygen, so residual ozone is not dangerous to the body and does not affect the organoleptic properties of water. Control of ozonation is less complicated than chlorination, since ozonation does not depend on factors such as temperature, water pH, etc. To disinfect water, the required dose of ozone is on average 0.5-6 mg/l with an exposure of 3-5 minutes. Ozonation is carried out using special devices - ozonizers.

Chemical methods of water disinfection also use the oligodynamic effects of heavy metal salts (silver, copper, gold). The oligodynamic effect of heavy metals is their ability to exert a bactericidal effect over a long period of time at extremely low concentrations. The mechanism of action is that positively charged heavy metal ions interact in water with microorganisms that have a negative charge. Electroadsorption occurs, as a result of which they penetrate deep into the microbial cell, forming heavy metal albuminates (compounds with nucleic acids) in it, as a result of which the microbial cell dies. This method is usually used to disinfect small quantities of water.

Hydrogen peroxide has long been known as an oxidizing agent. Its bactericidal effect is associated with the release of oxygen during decomposition. The method of using hydrogen peroxide for water disinfection has not yet been fully developed.

Chemical, or reagent, methods of water disinfection, based on adding one or another chemical substance to it in a certain dose, have a number of disadvantages, which consist mainly in the fact that most of these substances negatively affect the composition and organoleptic properties of water. In addition, the bactericidal effect of these substances appears after a certain period of contact and does not always apply to all forms of microorganisms. All this was the reason for the development of physical methods of water disinfection, which have a number of advantages over chemical ones. Reagent-free methods do not affect the composition and properties of disinfected water and do not impair its organoleptic properties. They act directly on the structure of microorganisms, as a result of which they have a wider range of bactericidal effects. A short period of time is required for disinfection.

The most developed and technically studied method is irradiation of water with bactericidal (ultraviolet) lamps. UV rays with a wavelength of 200-280 nm have the greatest bactericidal properties; the maximum bactericidal effect occurs at a wavelength of 254-260 nm. The radiation source is low-pressure argon-mercury lamps and mercury-quartz lamps. Water disinfection occurs quickly, within 1-2 minutes. When water is disinfected with UV rays, not only vegetative forms of microbes are killed, but also spore forms, as well as viruses, helminth eggs that are resistant to chlorine. The use of bactericidal lamps is not always possible, since the effect of water disinfection with UV rays is affected by the turbidity, color of the water, and the content of iron salts in it. Therefore, before disinfecting water in this way, it must be thoroughly cleaned.

Of all the available physical methods of water disinfection, boiling is the most reliable. As a result of boiling for 3-5 minutes, all microorganisms present in it die, and after 30 minutes the water becomes completely sterile. Despite the high bactericidal effect, this method is not widely used for disinfecting large volumes of water. The disadvantage of boiling is the deterioration of the taste of water, which occurs as a result of volatilization of gases, and the possibility of more rapid development of microorganisms in boiled water.

Physical methods of water disinfection include the use of pulsed electric discharge, ultrasound and ionizing radiation. Currently, these methods are not widely used in practice.

Special ways to improve water quality. In addition to the basic methods of water purification and disinfection, in some cases it becomes necessary to carry out special treatment. This treatment is mainly aimed at improving the mineral composition of water and its organoleptic properties.

Deodorization - removal of foreign odors and tastes. The need for such treatment is determined by the presence in water of odors associated with the vital activity of microorganisms, fungi, algae, decay products and decomposition of organic substances. For this purpose, methods such as ozonation, carbonization, chlorination, water treatment with potassium permanganate, hydrogen peroxide, fluoridation through sorption filters, and aeration are used.

Degassing of water is the removal of dissolved, foul-smelling gases from it. For this purpose, aeration is used, i.e., spraying water into small drops in a well-ventilated room or in the open air, resulting in the release of gases.

Water softening is the complete or partial removal of calcium and magnesium cations from it. Softening is carried out with special reagents or using ion exchange and thermal methods.

Desalination (desalination) of water is often carried out when preparing it for industrial use.

Partial desalination of water is carried out to reduce the salt content in it to the level at which the water can be used for drinking (below 1000 mg/l). Desalination is achieved by distillation of water, which is produced in various desalination plants (vacuum, multi-stage, solar thermal), ion exchange installations, as well as by electrochemical methods and the freezing method.

Deferrization - removal of iron from water is carried out by aeration followed by settling, coagulation, liming, and cationization. Currently, a method has been developed for filtering water through sand filters. In this case, ferrous iron is retained on the surface of sand grains.

Defluoridation is the release of natural waters from excess fluorine. For this purpose, a precipitation method is used, based on the sorption of fluorine by a precipitate of aluminum hydroxide.

If there is a lack of fluoride in water, it is fluoridated. If water is contaminated with radioactive substances, it is subjected to decontamination, i.e., removal of radioactive substances.