The procedure for washing and disinfecting pipelines and drinking water supply structures. Water disinfection, water chlorination “Chlorine water” and hypochlorous acid

INSTRUCTIONS*
on control over disinfection of household and drinking water
and disinfection of water supply facilities with chlorine
with centralized and local water supply**

________________
* Prepared by the A.N. Sysin Institute of General and Communal Hygiene of the USSR Academy of Medical Sciences.

** The term “disinfection” refers to the treatment of water, and the term “disinfection” refers to the treatment of water supply facilities and networks with disinfectants.

APPROVED by Deputy Chief Sanitary Doctor P. Lyarsky on November 25, 1967 N 723a-67.

The instructions are intended for sanitary doctors monitoring the domestic and drinking water supply of populated areas. Guided by these instructions, the sanitary and epidemiological service authorities impose sanitary requirements on the administration of water supply systems or on the owners of local water sources, who are responsible for providing the population with good-quality drinking water.

I. Chlorination of water in water pipelines

The quality of water in centralized water supply depends on the quality of water sources, water intake conditions, the correct organization of sanitary protection zones and the implementation of the appropriate regime in them, the regime of water purification and disinfection, as well as on the sanitary and technical condition of water intake devices and water distribution networks. In order to provide the population with good-quality drinking water, it is necessary to strictly observe sanitary requirements when installing and operating all water supply structures, including water chlorination plants.

2. Chlorination of water must be carried out in all cases of receiving it from surface water bodies (after mandatory preliminary purification), as well as when receiving water from underground sources, the bacterial indicators of which do not comply with GOST "Drinking Water".

Note: Other methods approved by the Main Sanitary and Epidemiological Directorate of the USSR Ministry of Health can be used to disinfect water.

3. Chlorination of water in water supply systems should be carried out, as a rule, using liquid chlorine. For stations with a capacity of up to 3000 m3/day, the use of bleach or calcium hypochlorite in the form of two-thirds basic salt (DTSGK) is allowed. Reagents used for chlorination of water must be subjected to control analysis at a water supply station to check the content of active chlorine and other components in them, in accordance with established standards (“Liquid chlorine” - GOST 6718-53, “Lime chlorine” - GOST 1692-58 , "Temporary instructions for the use of DTSGK for disinfection purposes", approved by the USSR Ministry of Health on November 6, 1960 N 311-60).

4. In order to establish indications for chlorination of water sources used for domestic and drinking water supply, as well as in order to develop basic provisions for the chlorination regime, a preliminary sanitary and laboratory examination of the water source is carried out in accordance with the program provided for in force.

5. In order to establish the working dose of chlorine for chlorination, the effect of water disinfection and the amount of residual active chlorine, which depends on the amount of chlorine absorption of water, is determined experimentally.

The working dose of chlorine selected for water disinfection must ensure the proper bactericidal effect, i.e. the number of E. coli in the treated water should be no more than 3 per 1 liter, the total number of bacteria - no more than 100 per 1 ml after the contact period of water with chlorine (at least 30 minutes). The residual chlorine content must be no less than 0.3 and no more than 0.5 mg/l (GOST "Drinking Water").

6. When chlorinating water from some sources, mainly open ones, difficulties may arise due to the need to obtain the proper disinfection effect and at the same time ensure that the water meets hygienic requirements in terms of organoleptic properties (smell and taste). In such cases, one or another of the special disinfection techniques should be used, which include the following:

a) Double chlorination, i.e. introduction of chlorine preliminarily before treatment facilities into the suction water pipelines of the 1st rise (usually in doses of 3-5 mg/l) and finally after the filters (usually in doses of 0.7-2 mg/l); used when the source water is highly colored and contains a high content of organic matter and plankton.

b) Chlorination with preammonization, i.e. introduction of ammonia or its salts into water immediately before the introduction of chlorine (usually with ammonia and chlorine dose ratios of 1:4, 1:10). In this case, disinfection is ensured by combined chlorine (chloramines). This method is used to prevent specific odors that arise after treating water with chlorine. When preammoniation, the contact of water with chlorine should be at least 1 hour.

c) Rechlorination, i.e. introduction of obviously high doses of chlorine (up to 10-20 mg/l) with subsequent binding of excess chlorine (dechlorination with sulfur dioxide or activated carbon); used in cases of forced use of water sources whose bacterial contamination exceeds the limit established by GOST 2761-57, i.e. the average number of E. coli is more than 10,000 per liter (in water samples taken at the point of water intake). In addition, it is used to avoid the appearance of chlorine-phenolic odor in the presence of phenols in the source water.

d) Chlorination with post-fracture doses, i.e. taking into account the turning point on the residual chlorine curve; in this case, water is disinfected with free chlorine, which is much more effective than combined chlorine (chloramines); used mainly in cases of high bacterial contamination of source water.

e) The use of chlorine dioxide can also be recommended to increase the efficiency of disinfection and prevent specific odors in water.

7. The choice of one or another chlorination method, guaranteeing full compliance of drinking water with the requirements of GOST "Drinking Water", is carried out by the administration of the water supply station on the basis of sanitary-chemical, sanitary-bacteriological and technological analyzes of raw and treated water, taking into account production experience in its purification and disinfection .

8. Based on the data obtained in accordance with paragraphs 5-7, the water supply administration establishes the basic provisions for the method of treating water with chlorine, which include the scheme for using chlorine, dosage of reagents and chlorination schedules, depending on water consumption. These basic provisions must be agreed upon with the local sanitary and epidemiological service authorities.

Laboratory and production control over the quality of water at the water supply station and in the distribution network is provided by the administration of the water supply system, the forces and means of the departmental laboratory in accordance with GOST "Drinking Water". Determination of residual chlorine before supply to the network is carried out every hour, and on water supply systems from open reservoirs - every 30 minutes; There, a sample is taken for bacteriological analysis at least once a day, simultaneously with the next determination of residual chlorine.

9. Sanitary laboratory control over the effectiveness of chlorination of water supplied by the water supply system for household and drinking needs is carried out by the sanitary-epidemiological station by determining the number of E. coli and the total number of bacteria at the most characteristic points of water supply (closest to the pumping station, the most distant, the most elevated, dead ends, standpipes). Sampling points and frequency of analyzes are determined by schedules approved by local sanitary and epidemiological service authorities.

10. Quantitative determination of residual active chlorine in water is carried out using the iodometric or orthotolidine method, a description of which is given in Appendix No. 1.

The iodometric method is preferable at active chlorine concentrations of at least 0.5 mg/l, the orthotolidine method at lower concentrations.

To determine residual chlorine in large water supply systems, it is advisable to use automatic analyzers, in particular photoelectronic systems of the Academy of Public Utilities of the RSFSR, which provide continuous recording of residual chlorine in water.

In chlorination practice, there may be a need to separately determine the main forms of active chlorine, in particular, during chlorination with post-turnover doses (free chlorine) and during chlorammonization (combined chlorine). Free chlorine has a relatively quick disinfecting effect, while combined chlorine is less effective (see paragraph 6-d above). For their separate quantitative determination, a method based on the use of para-aminodimethylaniline should be used (see Appendix No. 1). International drinking water standards also recommend the orthotolidine-arsenite method, which has not yet found application in the USSR.

11. When performing work on water chlorination, the safety measures specified in Appendix No. 2 must be observed.

The storage conditions for chlorine and ammonia reserves must meet the requirements of the current Sanitary Rules for the design, equipment and maintenance of warehouses for storing potent toxic substances (approved by the USSR Ministry of Health on June 24, 1965 N 534-65). In this case, ammonia must be stored separately from chlorine.

Storage of bleach reserves is allowed only in undamaged standard packaging, in closed warehouses, dry, dark and well ventilated, at an air temperature not exceeding 20 ° C. It is prohibited to store explosives and flammable substances, lubricating oils, food products, metal products and gas cylinders in the same room with bleach.

12. The sanitary and epidemiological service authorities, in the process of scheduled inspections of water supply systems, as well as for epidemic indications (at least once a month), must check the correctness of laboratory and production control over water quality, including the correctness of the basic provisions for the method of treating water with chlorine, established by the water supply administration (see clause 8 of these instructions).

All comments and suggestions for improving the sanitary condition of the water supply main structures, processing methods and improving water quality must be entered into a special journal of the established form, stored at the water supply station.

13. In the absence of a departmental laboratory (on low-power water supply systems), for production control over the operation of the station, a full-time position of a laboratory assistant should be provided, who monitors the correctness of chlorination and performs simple tests (the content of active chlorine in bleach, in prepared chlorine solutions, determination residual chlorine in water, etc.).

II. Chlorination of water in local water supplies

14. With local water supply, i.e. When using water without a distribution network of pipes, directly from a source (wells, springs, open reservoirs), chlorination of water that requires disinfection is usually done with bleach in clean containers - tanks, barrels, tanks or other special containers. In this case, the following conditions must be observed:

a) bleach is introduced into the water in a dose established experimentally;

b) for reliable disinfection of water, its contact with chlorine should be less than 30 minutes in summer, and at least 1 hour in winter;

c) properly chlorinated water should contain residual chlorine in an amount of 0.3-0.5 mg per liter.

Note: In exceptional cases, in the absence of other possibilities, residual chlorine can be determined qualitatively by the blueness of chlorinated water from the addition of several crystals of potassium iodide and a few drops of a 1% starch solution, as well as by the presence of a faint odor of chlorine in the water.

15. A bleach solution is prepared with a strength of 1-5%, i.e. To prepare the solution, take 10-50 g of bleach per 1 liter of water. In the absence of scales, you can use spoons, glasses and other objects of known capacity to measure lime, taking the capacity of a teaspoon as 2-2.5 g of bleach, a tablespoon as 9-12 g, a glass as 120 g.

A measured amount of bleach is poured into a mug or bowl, a little water is added to it and ground into a creamy mass without lumps. Then this mass is diluted with the required amount of water and mixed thoroughly. The prepared bleach solution is used for chlorination after settling. The content of active chlorine in bleach and the selection of the working dose of chlorine is carried out in accordance with Appendix No. 1.

16. In some cases, depending on the quality of water, in order to increase the reliability of its disinfection, it is recommended to use rechlorination, i.e. introduction of obviously excessive doses of active chlorine with subsequent removal or chemical binding of excess chlorine.

Rechlorination is carried out as follows. A solution of bleach is added to the water at a rate of at least 10 mg/l of active chlorine, and when disinfecting contaminated water from open sources - at least 20 mg/l of active chlorine. After thoroughly mixing the bleach solution poured into the water using a wooden shovel or paddle, leave the water alone for 15 minutes in the summer and 30 minutes in the winter. After this, the smell of the water is checked: if there is a strong smell of chlorine, rechlorination is considered sufficient; if there is no smell or a very weak smell of chlorine, it is necessary to repeat the introduction of bleach.

To remove excess chlorine (dechlorination), water is filtered through activated or regular charcoal, and in the absence of charcoal, sodium hyposulfite is added to the water (at the rate of 3.5 mg of hyposulfite per 1 mg of active residual chlorine).

17. Disinfection of mine wells and disinfection of water in them is carried out in accordance with the “Temporary instructions for the disinfection of mine wells and disinfection of water in them,” approved by the Main Sanitary and Epidemiological Directorate of the USSR Ministry of Health on January 18, 1967 N 663-67.

III. Disinfection of water supply structures with chlorine during their construction and operation

18. Disinfection of water supply facilities (wells, reservoirs and pressure tanks, settling basins, mixers, filters, water supply networks) can be preventive (before commissioning of new structures, after periodic cleaning, after repair and emergency work), as well as for epidemic indications ( in case of contamination of structures, which creates a threat of waterborne outbreaks of intestinal infections).

19. To increase the reliability of disinfection and reduce its duration, it is recommended to use solutions with an active chlorine concentration of 75-100 mg/l with contact for 5-6 hours. It is possible to use solutions with a lower concentration of active chlorine - 40-50 mg/l, but the duration of the required contact in this case increases to 24 hours or more.

20. Before disinfecting water supply facilities, in all cases it is necessary to carry out preliminary mechanical cleaning and rinsing. The water supply network, the cleaning of which is difficult, is intensively washed for 4-5 hours at the maximum possible speed of water movement (at least 1 m/sec.).

21. Disinfection of artesian wells before putting them into operation is carried out in cases where, after washing them, the quality of water according to bacteriological indicators does not correspond to GOST "Drinking Water".

During the operation of wells, the need for disinfection arises when water contamination is detected directly in the well due to its defects (in such cases, disinfection must be preceded by appropriate repair work).

Disinfection is carried out in two stages: first, the above-water part of the well, then the underwater part. To disinfect the surface part of the well, a pneumatic plug is installed several meters below the static level, above which the well is filled with a solution of chlorine (or bleach) with an active chlorine concentration of 50-100 mg/l, depending on the degree of expected contamination. After 3-6 hours of contact, the plug is removed and, using a special mixer, a chlorine solution is introduced into the underwater part of the well so that the concentration of active chlorine after mixing with water is at least 50 mg/l. After 3-6 hours of contact, pumping is carried out until the noticeable smell of chlorine disappears in the water, after which a water sample is taken for control bacteriological analysis.

Note: The calculated volume of chlorine solution is taken to be greater than the volume of wells (in height and diameter): when disinfecting the above-water part - 1.2-1.5 times, underwater part - 2-3 times.

22. It is recommended to disinfect large-capacity tanks using the irrigation method. A solution of bleach (or chlorine) with a concentration of 200-250 mg/l of active chlorine is prepared at the rate of 0.3-0.5 l per 1 m of the inner surface of the tank. This solution is used to cover the walls and bottom of the tank by irrigation from a hose or hydraulic remote control.
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According to many experts, water chlorination is the largest invention in medicine, or rather in preventive hygiene of the 20th century, which brought enormous benefits to humans...

Water chlorination is the treatment of water with chlorine and its compounds. The most common method of disinfecting drinking water; is based on the ability of free chlorine and its compounds to inhibit microbial enzyme systems that catalyze redox processes.

Story

According to many experts, water chlorination is the largest invention in medicine, or rather in preventive hygiene of the 20th century, which has brought enormous benefits to humans. It was chlorination of water, not the discovery of antibiotics, insulin or heart transplants that saved the most lives. It stopped the spread of intestinal infections in cities.

Chlorination of water as a means of disinfection began at the beginning of the 20th century. Chlorine was first used to disinfect water in London after the cholera epidemic of 1870. In Russia, water chlorination was carried out in 1908, also in connection with the cholera epidemic. Subsequently, it was held in Kronstadt, Nizhny Novgorod, Rostov-on-Don, and St. Petersburg. At the first stage, however, it was of a parodic nature. In subsequent years, water chlorination as an effective means of combating infectious diseases has spread rapidly throughout the world and is now used by many hundreds of millions of people.

It's no secret that chlorine is poison. The poison is so strong that chlorine was one of the first gases used in the First World War as a chemical weapon. The toxicity of chlorine is associated with its high oxidizing ability - it is one of the three most powerful halogens. This in turn means that chlorine is capable of destroying any organic matter and creating organochlorine compounds based on it.

Recently, new methods of water disinfection have appeared. But they are still more expensive than chlorination and do not guarantee against contamination of already treated water after it has gone through the pipes. Therefore, it is too early to abandon chlorine. In any case, when chlorine was abandoned in Peru to reduce the number of cancers, it led to a severe outbreak of cholera.

Process

To chlorinate water at water treatment plants, liquid chlorine and bleach are used (for low-capacity stations). When chlorine is added to water, hypochlorous and hydrochloric acids are formed.
C12 + H2O = HOC1 + HC1
Next, the resulting hypochlorous acid dissociates
NOS1 ** N+ + OS1-
The hypochlorite ions OC1~ resulting from the dissociation of hypochlorous acid have, along with undissociated hypochlorous acid molecules, bactericidal properties.
The sum of C12+HOC1+OC1- is called free active chlorine.

The amount of active chlorine required for water disinfection should be determined not by the number of pathogenic bacteria, but by the entire number of organic substances and microorganisms (as well as inorganic substances capable of oxidation) that may be present in the chlorinated water.

The correct dosage of chlorine is extremely important. An insufficient dose of chlorine may result in it not having the necessary bactericidal effect; An excessive dose of chlorine worsens the taste of water. Therefore, the dose of chlorine should be set depending on the individual properties of the water being purified based on experiments with this water.

The calculated dose of chlorine when designing a disinfection installation should be taken based on the need to purify water during the period of maximum pollution (for example, during floods).

An indicator of the adequacy of the dose of chlorine taken is the presence in the water of so-called residual chlorine (remaining in the water from the administered dose after the oxidation of substances in the water). According to the requirements of GOST 2874-73, the concentration of residual chlorine in water before entering the network should be in the range of 0.3-0.5 mg/l.

For clarified river water, the dose of chlorine usually ranges from 1.5-3 mg/l; when chlorinating groundwater, the dose of chlorine most often does not exceed 1-1.5 mg/l; in some cases, it may be necessary to increase the dose of chlorine due to the presence of ferrous iron in the water. With an increased content of humic substances in water, the required dose of chlorine increases.

When introducing chlorine into the water being treated, good mixing with water and a sufficient duration (at least 30 minutes) of its contact with water before supplying it to the consumer must be ensured. Chlorination of already clarified water is usually carried out before it enters the clean water reservoir, where the time necessary for their contact is ensured.

What are the benefits of water chlorination?

The widespread use of chlorine in water treatment technologies has been facilitated by its effectiveness in disinfecting natural waters and its ability to preserve already purified water for a long time. In addition, preliminary chlorination of water allows you to reduce the color of water, eliminate its odor and taste, reduce the consumption of coagulants, and also maintain a satisfactory sanitary condition of treatment facilities at water treatment plants.

Efficiency, availability and reasonable cost, as well as extensive experience with this reagent, have provided chlorine with an exceptional role - more than 90% of water stations in the world disinfect and decolorize water with chlorine, consuming up to 2 million tons of this liquid reagent per year.

However, chlorine as a water treatment reagent has significant disadvantages. For example, chlorine and chlorine-containing compounds are highly toxic, which requires strict compliance with increased safety requirements. Chlorine affects mainly vegetative forms of microorganisms, with gram-positive strains of bacteria more resistant to chlorine than gram-negative strains of microorganisms.

Viruses, spores and protozoan cysts and helminth eggs are also highly resistant to chlorine. The need to transport, store and use significant amounts of liquid chlorine at water supply stations, as well as the discharge of this substance and its compounds into the environment, has caused a high environmental hazard. In addition, chlorine is highly corrosive.

What's the problem?

The most important problem of this method is the high activity of chlorine; it enters into chemical reactions with all organic and inorganic substances in the water. Water from surface sources (which are mainly sources of water intake) contains a huge amount of complex organic substances of natural origin, and in most large industrial cities, dyes, surfactants, petroleum products, phenols, etc. enter the water with industrial wastewater.

When chlorinating water containing the above substances, chlorine-containing toxins, mutagenic and carcinogenic substances and poisons are formed, including dioxides, namely:

Chloroform, which has carcinogenic activity

Dichlorobromomethane, bromomethane chloride, tribromomethane - having mutagenic properties

2,4,6-trichlorophenol, 2-chlorophenol, dichloroacetonitrile, chlorohieredin, polychlorinated biphenyls - which are immunotoxic and carcinogenic substances

Trihalomethanes - carcinogenic chlorine compounds

These substances have a delayed killing effect on the human body. Purifying drinking water from chlorine does not solve the problem, since many of the dangerous compounds formed in water during its chlorination enter the human body through the skin, during washing, bathing or visiting the pool. According to some reports, taking an hour-long bath containing excessive amounts of chlorinated water corresponds to ten liters of drunk chlorinated water.

The first attempts to link cancer incidence in the population with the quality of drinking water were made back in 1947. But until 1974, water chlorination was not in any way associated with oncology. It was believed that chlorinated water has no adverse effects on human health.

Unfortunately, data on the connection between the consumption of chlorinated drinking water from surface water sources and the incidence of malignant neoplasms in the population began to accumulate only in the 70s. Therefore, there are still different points of view on this matter. According to some researchers, drinking contaminated water may be associated with 30 to 50% of cases of malignant tumors. Others cite calculations according to which the consumption of river water (compared to water from underground sources) can lead to an increase in cancer incidence by 15%.

Why is chlorine dangerous when it enters the human body?

The side effect of harmful chlorine exposure can be caused in two ways: when chlorine enters the body through the respiratory tract, and when chlorine penetrates the skin. Scientists all over the world are researching this problem. They associate many dangerous diseases with the ingestion of chlorine or harmful byproducts of water chlorination into the human body. These diseases include: bladder cancer, stomach cancer, liver cancer, rectal cancer.

But it’s not just the digestive organs that suffer. Chlorine can also cause heart disease, atherosclerosis, anemia, and high blood pressure. In addition, chlorine dries the skin (remember the feeling of tightness of the skin after a swimming pool), destroys the structure of the hair (it begins to fall out more, becomes brittle, dull, lifeless), and irritates the mucous membrane of the eyes.

US epidemiologists conducted a study: they compared a map of water chlorination with a map of the distribution of bladder and digestive cancers. A direct relationship was revealed: the higher the chlorine content in the water, the more common the disease.

So what should we do?

So far, chlorination is the most proven and cheapest method of water disinfection. In the next 20 years, water chlorination will be used at most water treatment stations of all Russian water utilities, gradually being replaced by alternative methods - ozonation and ultraviolet radiation. After the chlorination process, free chlorine evaporates from the water, however, residual chlorine is always present in tap water, sometimes, especially during floods, in elevated concentrations. Therefore, it is recommended to let the water stand for 24 hours before drinking.

To ensure that chlorine is removed from water, use a good filter that will remove all harmful impurities and make it taste good.

It should be remembered that the water passed through the filter is cleared of most contaminants, including chlorine, which kills bacteria. You should not stock up on such water for future use, because it is devoid of the “preservative” - chlorine, and bacteria begin to multiply in clean and warm water that is pleasant for them especially quickly. If you still decide to store purified water for longer than a day, keep it in the refrigerator in a container made of neutral material - glass or food-grade plastic.

Must be produced regularly, not only of those that are currently in operation, but also of new ones, before they are launched. This is also necessary in order to check their tightness and properly disinfect them. In most cases, before starting disinfection and flushing, it is necessary to clean the water supply system from foreign elements that may get there during the construction process. This is done through special bypass pipelines connected to the existing one under pressure. The speed of water movement should be as high as possible, but not less than one meter per second when completely filled.

Flushing and disinfection are carried out until the water in the water supply pipeline is completely cleared of dirt, turbidity and other contaminants. If the diameter of the pipeline is more than 900 millimeters, then they are carefully inspected from the inside before flushing begins, and if foreign objects are found, they are removed. Based on the number of outlets and their location on the pipeline, disinfection and flushing can be carried out in separate sections, the length of which ranges from one to three kilometers for main water supply systems and up to one kilometer for distribution networks. If there are no outlets in the pipeline area to be flushed, flushing can be carried out through special hydrants or fittings adapted for these purposes.

After washing and disinfection of water supply pipelines will be completed, and hydraulic tests will also be carried out, a report will be drawn up indicating the test date and duration. Disinfection is carried out with a chlorine solution, the concentration of which is 40 milligrams per liter. The pipeline is filled with a chlorine-containing solution and it remains there for at least a day. Then you should check the presence of chlorine in the water - it should be at least one milligram per liter.

At the end of all work, the water is drained, followed by repeated thorough flushing with clean water from the existing water supply system at the highest possible speed and complete filling of the pipeline using special ones. During this washing process, it is necessary to periodically take water for laboratory analysis.

Naturally, the quality of the water being tested must fully comply with the provisions of the standards and the requirements of sanitary and hygienic standards. And if, after analyzing water taken sequentially after some time, the results completely coincide and comply with established standards, washing and disinfection can be considered successfully completed. If, after repeated flushing, the quality of drinking water does not fully comply with current norms and standards, the water supply pipeline should be subjected to further treatment.

After disinfection, the remaining water discharged from the water supply is diluted with clean water until the chlorine concentration reaches 2-3 milligrams per liter (maximum). When draining it, you must ensure that it does not get into open water bodies, fish nurseries, water sources for livestock, or flood crops, vegetable gardens, etc.

Washing and disinfection of water supply pipelines carried out by the efforts and funds of the installation organization and with the obligatory presence of an employee of the State Sanitary and Epidemiological Supervision service and the operation service, who take water samples for laboratory analysis. A laboratory representative monitors the characteristics of the disinfectant solution and determines the amount of chlorine contained in the rinsing solution. After obtaining the optimal result, a representative of the State Sanitary and Epidemiological Supervision service draws up a protocol indicating the results of the tests performed.

The final results are documented in a special act, which is drawn up in the presence of representatives of the installation organization, the laboratory of the sanitary and epidemiological station, and the operation service. The report indicates the date of the water supply pipeline, its duration, the concentration of the flushing solution (the amount of chlorine contained) and the results obtained.

Timely flushing and disinfection of pipelines is one of the most important conditions for ensuring the uninterrupted and, accordingly, high-quality functioning of any water supply systems. The fact is that during long-term operation of systems of this type, the internal sides and connections of the pipeline are covered with various kinds of deposits, rust, etc.

One part of such contaminants comes with water, the other part is formed during the corrosion of metal water pipes directly inside the system itself. As a result, such contaminants not only significantly reduce the quality of the supplied water, but also negatively affect such operational indicators of shut-off valves as the smooth opening/closing of taps, their tightness, etc. It is in order to return the water supply system to its original (original) state that periodic flushing of pipelines, as well as their disinfection.

Chlorination and flushing of networks in Nizhny Novgorod at low prices

Today, the Nizhny Novgorod company “SetStroy-Engineering” carries out the entire range of work on flushing and disinfection of drinking, fire, technical, cold and hot water supply systems. Thanks to the availability of the necessary equipment, such procedures can be carried out at almost any facility: in apartment and private buildings, office and shopping and entertainment centers, in buildings and structures for industrial purposes, etc.

II. Chlorination of water in local water supply14. With local water supply, i.e. When using water without a distribution network of pipes, directly from a source (wells, springs, open reservoirs), chlorination of water that requires disinfection is usually carried out with bleach in clean containers - tanks, barrels, tanks or other special containers. In this case, the following conditions must be observed:

a) bleach is introduced into the water in a dose established experimentally;

b) for reliable disinfection of water, its contact with chlorine must be at least 30 minutes in summer, and at least 1 hour in winter;

c) properly chlorinated water should contain residual chlorine in an amount of 0.3-0.5 mg per liter.

Note: In exceptional cases, in the absence of other possibilities, residual chlorine can be determined qualitatively by the blueness of chlorinated water from the addition of several crystals of potassium iodide and a few drops of a 1% starch solution, as well as by the presence of a faint odor of chlorine in the water.

A measured amount of bleach is poured into a mug or bowl, a little water is added to it and ground into a creamy mass without lumps. Then this mass is diluted with the required amount of water and mixed thoroughly. The prepared bleach solution is used for chlorination after settling. The content of active chlorine in bleach and the selection of the working dose of chlorine is carried out according to Appendix No. 1.

Rechlorination is carried out as follows. A solution of bleach is added to the water at a rate of at least 10 mg/l of active chlorine, and when disinfecting contaminated water from open sources - at least 20 mg/l of active chlorine. After thoroughly mixing the bleach solution poured into the water using a wooden shovel or oar, leave the water alone for 15 minutes in summer, and 30 minutes in winter. After this, the smell of the water is checked: if there is a strong smell of chlorine, rechlorination is considered sufficient; if there is no smell or a very weak smell of chlorine, it is necessary to repeat the introduction of bleach.

To remove excess chlorine (dechlorination), water is filtered through activated or regular charcoal, and in the absence of charcoal, sodium hyposulfite is added to the water (at the rate of 3.5 mg of hyposulfite per 1 mg of active residual chlorine).

17. Disinfection of mine wells and disinfection of water in them is carried out in accordance with the “Temporary instructions for the disinfection of mine wells and disinfection of water in them,” approved by the Main Sanitary and Epidemiological Directorate of the Ministry of Health of the USSR on January 18, 1967 N 663-67.

III. Disinfection of water supply structures with chlorine during their construction and operation

During the operation of wells, the need for disinfection arises when water contamination is detected directly in the well due to its defects (in such cases, disinfection must be preceded by appropriate repair work).

Disinfection is carried out in two stages: first, the above-water part of the well, then the underwater part. To disinfect the surface part of the well, a pneumatic plug is installed several meters below the static level, above which the well is filled with a solution of chlorine (or bleach) with an active chlorine concentration of 50-100 mg/l, depending on the degree of expected contamination. After 3-6 hours of contact, the plug is removed and, using a special mixer, a chlorine solution is introduced into the underwater part of the well so that the concentration of active chlorine after mixing with water is at least 50 mg/l. After 3-6 hours of contact, pumping is carried out until the noticeable smell of chlorine disappears in the water, after which a water sample is taken for control bacteriological analysis.

Note: The calculated volume of chlorine solution is taken to be greater than the volume of wells (in height and diameter): when disinfecting the surface part - 1.2-1.5 times, the underwater part - 2-3 times.

22. It is recommended to disinfect large-capacity tanks using the irrigation method. A solution of bleach (or chlorine) with a concentration of 200-250 mg/l of active chlorine is prepared at the rate of 0.3-0.5 l per 1 m 2 of the internal surface of the tank. This solution is used to cover the walls and bottom of the tank by irrigation from a hose or hydraulic remote control.

After 1-2 hours, the disinfected surfaces are washed with clean tap water, removing the waste solution through the mud outlet. Work must be carried out in special clothing, rubber boots and gas masks; Before entering the tank, install a tank with a solution of bleach for washing boots.

Small-capacity pressure tanks should be disinfected using the volumetric method, filling them with a solution with a concentration of 75-100 mg/l of active chlorine. After contact for 5-6 hours, the chlorine solution is removed through the mud pipe and the tank is washed with clean tap water (until the rinse water contains 0.3-0.5 mg/l of residual chlorine). In a similar way, sedimentation tanks, displacers, and filters are disinfected after they have been repaired and loaded.

A control bacteriological analysis after disinfection of structures is done at least 2 times with an interval corresponding to the time of complete exchange of water between sampling. If the analysis results are favorable, the structures can be put into operation.

23. Disinfection of the water supply network is carried out by filling the pipes with a solution of chlorine (or bleach) with a concentration of 75 to 100 mg/l of active chlorine (depending on the degree of contamination of the network, its deterioration and the sanitary and epidemic situation). The introduction of chlorine solution into the network continues until the points furthest from the point of its supply contain at least 50% of the given dose of active chlorine. From this moment, further supply of chlorine solution is stopped and the network filled with chlorine solution is left for at least 6 hours. At the end of contact, the chlorine water is drained and the network is washed with clean tap water. The conditions for water discharge from the network are determined on site in agreement with the sanitary and epidemiological service authorities. At the end of washing (when the water contains 0.3-0.5 mg/l of residual chlorine), samples are taken from the network for control bacteriological analysis. Disinfection is considered complete when the results of two tests taken sequentially from one point are favorable.

Note: The estimated volume of chlorine solution for network disinfection is determined by the internal volume of the pipes with the addition of 3-5% (for the probable outflow). The volume of 100 m of pipes with a diameter of 50 mm is 0.2 m 3, 75 mm - 0.5 m 3, 100 mm - 0.8 m 3, 150 mm - 1.8 m 3, 200 mm - 3.2 m 3 , 250 mm - 5 m 3.

24. Washing and disinfection of water supply structures and networks is carried out by the forces and means of the construction organization (before putting them into operation) or the water supply administration (after repair and emergency work) in the presence of representatives of the sanitary and epidemiological service. The results of the work are documented in a report indicating the dosage of active chlorine, the duration of chlorination (contact) and final rinsing, and data from control water tests. Based on these materials, local sanitary and epidemiological service authorities give an opinion on the possibility of putting the structures into operation.

25. With the publication of this instruction, “Instructions for the disinfection of household and drinking water with chlorine for centralized and local water supply” N 203-56 of January 26, 1956 is cancelled.

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* Prepared by the Institute of General and Communal Hygiene named after A.N. Sysin Academy of Medical Sciences of the USSR.

** The term “disinfection” refers to the treatment of water, and the term “disinfection” refers to the treatment of water supply facilities and networks with disinfectants.