41. The composition of natural waters and the effect of their components on public health.

Dry residue   - mineral substances dissolved in water, remaining after evaporation of 1 l. water. It is considered to be good drinking water, the dry residue of which does not exceed 1000 mg in 1 liter. The biological role of the dry residue of water lies in the fact that, taking into account the geological conditions (high content of a certain salt group in the soil), it is possible to judge whether water is contaminated with substances found in the dry residue.

Total water hardness   - value depending on the content of alkaline earth metal salts in water - calcium and magnesium. It is measured in conditional degrees or in milligrams - equivalents. The amount of salts equivalent to 10 mg CaO in 1 l of water is taken as one degree. Soft water is considered to have a hardness (raw) less than 10º, moderately hard - from 10 to 20º and hard - more than 20º. The total hardness of drinking water should not exceed 7 mg-eq / l, which corresponds to 20º, in some cases up to 14 mg-eq / l is allowed.

Biological significance of hardness salts  is small. Very hard water can cause a laxative effect on a person who is used to soft water. Hard water should not be looked upon as a valuable source of calcium (100g of calcium cheese is more than 12l of water with a hardness of 24º).

Indirect influence of hard water on body functions can affect the worst absorption of food cooked in hard water, vegetables and meat are poorly boiled soft water, as proteins form insoluble complexes with alkalis of hard water, which prevent water from penetrating into products, which affects the quality of thermal water. food processing

Of great importance is the hardness of water in sanitary and technical performance. Hard water is inconvenient for washing the body, as it gives insoluble compounds with alkaline albuminates and fatty acids located on the surface of the skin, making it difficult to wash. Hard water soap requires much more, since foam does not form until insoluble calcic and magnesia salts drop out of the water. These insoluble salts, settling on clothing, change the properties of the fabric, giving it coarseness and making it difficult to color, which makes hard water unsuitable in the textile industry.

Hardness can sometimes serve as a sanitary indicator: an increase in hardness may depend on water pollution, since one of the reasons for increasing water hardness is the breakdown of organic matter, which results in carbon dioxide, which leaches the hardness salts calcium and magnesium from the soil. Hardness may also increase when alkaline wastewater (calcium and magnesium) is released into the water.

According to SanPiN2.1.4.1074-01 “Drinking water” dry residue of water (total mineralization) should be in the range of 1000–1500 mg / l, total hardness 7 mg-eq / l (MPC 10 mg-eq / l)

  Chlorides, hygienic value:

Chloride salts serve as a measure of water pollution by organic substances of animal origin. The excreta of humans and animals, especially urine, as well as kitchen slops contain a lot of sodium chloride, the joint presence in the water of a large amount of chlorides and ammonia indicates water pollution by urine.

Sulfates, hygienic value:

Exceeding the usual salt content of sulfuric acid can also be a sign of water contamination by animal debris, sulfur is an integral component of the proteinaceous, during the decomposition of which and subsequent oxidation sulfates are formed. The main importance of sulphates is that with their high content in water they spoil its taste and can cause intestinal upset in some people (laxative effect)

An important indicator of water pollution are ammonia, nitric and nitrous acid salts. If, parallel with them, a high oxidizability of water is found, then we can confidently say that the water is polluted with organic substances of animal origin.

Ammonia is the initial product of decay, and therefore its presence in ode speaks of fresh pollution. Salts of nitrous acid indicate a known long-standing contamination of the water source, as it takes some time for the first stage of ammonia to be mineralized (turning it into nitrides).

Nitric acid salts - nitrates are the final product of the mineralization of organic substances, and therefore their presence is an indicator of the longer term contamination of the water source.

These circumstances allow a differential approach to the assessment of biological water pollution. So, if only ammonia was detected in the water, and when re-analyzed it was not there, then we can conclude that water pollution has ceased. If salts of nitrous acid are detected simultaneously with ammonia, this indicates a clear trouble for the water source.

It should be borne in mind that ammonium salts are sometimes found in clean, mostly groundwater as a result of the reduction of nitrate contained in the soil. Therefore, the presence of ammonia in the absence of other signs of pollution does not always indicate the poor quality of water.

Nitrogen triad norms in water: ammonia 2 mg / l, nitrite ion-3 mg / ml, nitrate ion - 45 mg / l

Effect of nitrates on the body:  the content of nitric acid salts in water is of independent interest. The consumption of well water rich in nitrates causes severe illness in infants and preschool children, manifested in pathological phenomena of the mucous membranes of the eyes, lips and skin (blue), intestines and sometimes the cardiovascular system. The main symptom of the disease is the appearance of methemoglobin in the blood: under the influence of microflora, nitrates pass into nitrites, which are absorbed into the blood, leading to the formation of methemoglobin, the presence of the latter reduces to some extent the oxygen supply to the tissues.

Trace elements of water, norms and biological significance

Iron:  in water it usually occurs in the form of bicarbonic oxide. Ferruginous water is harmless to the body, however, a high content of iron in water gives it an unpleasant odor and reduces transparency as a result of the conversion of ferrous oxide to hydrate of iron oxide under the action of oxygen in the air, falling in the form of brown sediment. Economically, water with a high iron content is unfavorable in that it forms rusty stains on linen and damages water pipes due to the deposition of iron oxide hydrate on their walls and mass development in the pipes of ferruginous bacteria, which greatly narrows the lumen of the pipes.

Fluorine:its content in water is of interest in connection with its influence on the state of the teeth. The high content of fluoride in water causes fluorosis, which is expressed in the spotting of the enamel, in severe cases - enamel hypoplasia and even complete destruction of the crowns of the teeth. On the other hand, a very low concentration of fluoride in water is one of the reasons contributing to the development of another dental disease - caries.

Iodine:found in natural waters 10 µg / l or slightly more. Artesian waters are richest in iodine and poor in fresh open water bodies. These quantities constitute an insignificant share of the daily human need for iodine (150-200 μg) and food is the main source of it.

However, a decrease in the iodine content in water is associated with the incidence of goiter, since iodine deficiency usually coincides with areas of endemic goiter. The content of iodine in water is considered as a kind of indicator of its content in the environment: if iodine is low in water, then it is low in soil, plant products, and, finally, in animals and humans.

Lead, copper, zinc, arsenic, mercury, chrome  and many other elements can be found in water as incidental impurities that enter it from tanks and vessels in which water is stored, but mainly with industrial wastewater. These compounds are harmful to the body, so their content in water should not exceed the established maximum permissible concentrations, especially toxic ones in drinking water are absolutely not allowed.

The content of trace elements in drinking water: aluminum - 0.5 mg / l, barium - 0.1 mg / l, beryllium - 0.0002 mg / l, boron - 0.5 mg / l, iron - 0.3 mg / l, cadmium - 0.001 mg / l, manganese - 0.1 mg / l, copper - 0.1 mg / l, molybdenum - 0.25 mg / l, arsenic 0.05 mg / l, nickel - 0.1 mg / l, mercury - 0.0005 mg / l, lead - 0.03 mg / l, selenium - 0.01 mg / l, strontium - 7.0 mg / l, fluorides: IandIIclimatic areas - 1,5mg / l,III  climatic region - 1.2 mg / l.

  Diseases and geochemical endemia, their prevention.

Mass lesions can have a non-infectious nature, i.e., they can be caused by the presence of chemicals in the water - both mineral and organic impurities.

Lack or excess of certain elements in the soil leads to a lack or excess of them in the water of surface or underground water bodies that form in this area, and as a result, in drinking water. In addition, an abnormally high or low content of the chemical element was observed in food products of plant and animal origin. This in a certain way affected the health of people permanently residing in the area - they had registered diseases that were not detected in other regions. Such areas were called biogeochemical provinces, and the diseases registered there - geochemical endemics, or endemic diseases. There are also mercury (Gorny Altai), antimony (Fergana valley), copper-zinc (Baymak region), copper (Ural, Altai, Donetsk region of Ukraine, Uzbekistan), silicon (Chuvashia, Danubeysky regions of Bulgaria and Yugoslavia), chromium (North Kazakhstan, Azerbaijan) and other biogeochemical provinces.

Among the mentioned endemic diseases, endemic fluorosis, endemic caries, water-nitrate methemoglobinemia and endemic goiter are especially closely associated with the use of water.

In addition to fluorine and iodine, some trace elements in concentrations observed in the natural water of some biogeochemical provinces can adversely affect health. For example, in biogeochemical provinces with a high content of strontium in the water of deep underground horizons used for drinking, children were found to have impaired bone tissue development, in particular, delaying teething, and later closing springs. A decrease in the proportion of children of primary school age with a harmonious morphofunctional development was also observed. The pathogenesis of these disorders is associated with the fact that strontium and calcium are competitive in biochemistry during their distribution in the body, in particular in the skeletal system. The pathogenesis of the endemic level of the disease, which is observed in residents of Transbaikalia and other areas of Southeast Asia, is similar.

Preventiongeochemical endemia is mainly the addition of trace elements missing in water. Prevention of fluorosis is provided by the mechanization and automation of production; effective ventilation, respiratory protection; replacement of sources of drinking water supply or deftouring types of water facilities.

Norms of allowances and rations in a military unit. 1Main soldier rations and his physiological and hygienic assessment. 2Features for the organization of food for military personnel, the basic allowance standards that may be in a military unit and types of rations, the chemical composition of the main soldier ration, (the number of calories, proteins, fats, carbohydrates, vitamins: A, B1, B2, PP, C, mineral salts: calcium, phosphorus, iron), 3 physiological and hygienic assessment of a soldier's ration, the 4 main document regulating the nutrition of servicemen, 5 we prepare this document and the hygienic principles of its preparation.

1,2,3

4.5. Control over the state of storage facilities, the mode and procedure of storage, the quantitative and qualitative state of food, the legality and expediency of their use is carried out by officials of a military unit in accordance with the requirements of the Internal Service Charter of the Armed Forces and the regulations on the troop economy of the Armed Forces. The head of the medical service of the unit is obliged to monitor the fulfillment of sanitary requirements for receiving, storing and dispensing food, as well as the sanitary condition of the food warehouse and the quality of the food stored therein. If there are doubts about the quality of the products, he should send them for examination to the sanitary-epidemiological institution. The veterinarian of the compound (part) is obliged to: - monitor compliance with the veterinary and sanitary requirements for food when it is received, stored and dispensed; - to monitor the proper placement, laying, storage mode of food, for its timely refreshment; - to conduct a veterinary and sanitary examination of food and give an opinion on the procedure for its use. The head of the food service of a military unit is responsible for the proper maintenance, storage and saving of food, equipment and property. He is obliged to: - manage the work of the food warehouse; - promptly request and organize the receipt and storage of stocks of food, equipment, property; - monitor the timely refreshment of food in the warehouse; - provide seasonal harvesting of potatoes and vegetables, their processing and storage, as well as the preparation of ice, hay and straw for the needs of the part; - check at least once a month for the presence and quality of food, equipment and property in the food warehouse; - to ensure compliance with sanitary and hygienic requirements for food during its storage, as well as the content of the food warehouse; - ensure compliance with safety measures and fire prevention measures at the food warehouse. Catering in the military unit

In accordance with the Statute on Food Supply of the Armed Forces of the Republic of Armenia, in peacetime, full-service canteens of military units are being created for the organization of food for military personnel. Proper organization of troop strength is one of the most important conditions that contribute to the preservation and strengthening of health and the improvement of combat training of personnel. Therefore, the commanders and officers of the rear must constantly take care of the nutrition of the personnel, ensuring its benign, full, tasty and varied food. To accomplish these tasks it is required: - to exercise constant control over the completeness of bringing the products laid down according to the rations standards, to those who eat; - to plan the diet of the personnel correctly, to develop and observe the most appropriate diet for the various contingents of military personnel, taking into account the nature and characteristics of their combat training; - to equip and equip a dining room with due regard for the requirements that ensure the strict movement of the movement and the processing of products, the mechanization of labor-intensive work, the maintenance of all the premises in exemplary condition; - properly operate technological and refrigeration equipment, dining and kitchen utensils, timely maintain and repair them technically; - to use products rationally, reduce waste when processing them, it is imperative that you follow cooking rules when cooking; - strictly comply with sanitary and hygienic requirements when handling food, preparing, distributing food, and also to observe personal hygiene (cooks and other workers of the canteen); - properly organize the work of the daily dress at the canteen, ensuring the timely and high-quality execution of all work; - adhere to a strictly established serving of dining tables and the observance of personal hygiene by military servicemen and the rules of conduct in the canteen during meals; - to carry out activities aimed at improving the organization of troop nutrition - review contests for the best dining room, food conferences, food shows; - to constantly develop the farm with regard to the use of its products for planned and supplementary feeding of personnel; - regularly conduct studies with employees of the canteen, as well as monitoring and demonstration cooking of food, to raise the class level of the specialty of the cooking staff. According to the statute of the internal service of the Armed Forces of the Russian Federation, the commander of the military unit, his deputy for logistics, the head of the food service must be responsible for organizing a good-quality nutrition for the servicemen. The latter is directly responsible for organizing the benign and timely food of personnel and the sanitary condition of the service facilities. The main duties of the head of the medical service of a military unit in matters of personnel nutrition are: - participation in the development of a rational diet of personnel in relation to the nature of combat training activities of the unit; - sanitary and hygienic control over the physiological usefulness of nutrition; - control over the sanitary condition of food objects; - monitoring compliance with sanitary and hygienic requirements during transportation and storage of food products; - sanitary and hygienic control over the quality of food; - monitoring compliance with sanitary and hygienic requirements for cooking food, cooking and distributing food; - Medical monitoring of dietary nutrition; - monitoring the health of workers of food facilities and their compliance with the rules of personal hygiene; - organization and conduct of hygienic education and health education. The food regime of military personnel provides for the number of meals during the day, compliance with physiologically correct gaps between them, expedient distribution of food relying on rations during the day, as well as eating food in a strictly prescribed time schedule. Observance of proper diet contributes to the preservation of health, as well as increasing the body's resistance to various types of combat training loads. The development of the catering regime for military personnel is entrusted to the commander of the military unit, his deputy for logistics, the head of the medical unit and the head of the food services of the military unit. For personnel who eat according to the norms of a combined-arms, cadet, engineering and technical rations, three meals a day (breakfast, lunch and dinner) are organized in military units. According to the Charter of the internal service of the Armed Forces of Belarus, the intervals between meals should not exceed 7 hours. With this in mind, when drafting the daily routine of a military unit, breakfast is planned before the start of classes, lunch is after the end of the main classes, and dinner is 2 to 3 hours before the end of the day. Daily rations in three meals are divided by calories: for breakfast 30 - 35%, for lunch 40 - 45%, for dinner 20 - 30%. When working at night (night shifts, night marches, etc.) it is recommended for breakfast 20 - 25%, for lunch 30 - 35%, for dinner 40 - 45% of daily calories. The doctor must inform the unit commander of informed decisions on changing the diet depending on the characteristics of combat training and the daily routine. A set of products that make up the soldiers ration, allows you to cook benign and varied food. The combined ration contains: proteins - 113 g, fat - 105 g, carbohydrates - 661 g. The caloric content of the ration is 4334 K / calorie. Under normal conditions, the following dietary pattern is adopted in parts: hot food is taken three times a day - for breakfast, lunch and dinner, tea - 2 times (in the morning and in the evening).

The content of chloride ions in the water of natural water bodies varies widely. In river and lake waters, especially in the northern regions of our country (see Fig. 3.8), their concentration is low. However, with an increase in water salinity, absolute and relative amounts of C1 increase ;, in the seas and most of the salt lakes, it is the main anion; in sea water, chloride ions make up 87% of the mass of all anions. This is explained by the good solubility of calcium, magnesium, sodium chlorides (see p. 2.4.2.2) and the low solubility of Ca504 and CaC03. Therefore, with an increase in the salt content in water, such widespread ions as BO and C03 (HCO), reaching values ​​of the solubility product in the presence of Ca2 + ions (see Section 2.4.4), begin to precipitate, giving way to the C1 ion. [. ..]

The determination of chlorides serves as a control of the constancy of the salt background of the waste water, which changes during the purification in the organic part, and for judging the “consistency” of the samples analyzed. The chloride content ranges from 180 to 300 mg / l. [...]

The content of chlorides is below the permissible norm, therefore the use of wastewater in agriculture in the presence of sufficient areas is quite possible. However, it is first necessary to check whether and to what extent measures are needed to reduce, and in some cases, eliminate the unpleasant smell. [...]

The content of chlorides in water determines its suitability for drinking. For drinking water, the limit value is 200 mg / l. Water with a greater content of either salty or bitter in taste. The content of chlorides in water also determines the possibility of its use in agriculture, including for greenhouses and greenhouses. Depending on the type of plant, the limiting concentration of chlorides is 50-300 mg / l. [...]

Chlorides are an integral part of most natural waters. Like sulfates, they determine the non-carbonate hardness of water. The content of chlorides of natural origin has a large range of fluctuations. However, in the water of rivers the concentration of chlorides is low - it does not usually exceed 10 mg / l, therefore, an increased amount of chlorine ions indicates contamination of the source with wastewater. In water sources of centralized water supply, the concentration of chlorides should not exceed 350 mg / l. [...]

Chlorides are an integral part of most natural waters. The high content of chlorides of geological origin in surface waters is a rare phenomenon. Therefore, the detection of a large amount of chlorides is an indicator of water pollution by household or some industrial wastewater. In industrial wastewater, the chloride content depends on the nature of production. A gradual increase in the content of chlorides in surface waters can serve as a measure of pollution of reservoirs by sewage. [...]

Chlorides are the main ions of natural waters, have a large migration capacity, which is explained by their good solubility, poorly expressed ability to sorption on suspended substances and to consumption by aquatic organisms. Chlorides degrade the taste of water and make it unsuitable for drinking water supply, so the control of the chloride content in the water of water bodies is important for assessing water quality. For fishery water bodies, MPC chlorides is 300 mg / l. [...]

Chlorides are the predominant anion in highly mineralized waters. The concentration of chlorides in surface waters is subject to seasonal fluctuations, correlated with changes in the total water salinity. In unpolluted river waters and waters of fresh lakes, the chloride content varies from fractions of a milligram to tens and hundreds, in groundwater and sea waters — much higher. [...]

When the content of chlorides is less than 250 mg / l, 100 ml of filtered test water is taken. With a higher content of chlorides take 10-50 ml. The test water is poured into two conical flasks, made up to 100 ml with distilled water, 5 drops of K2Cr04 solution are added. The solution in one flask is titrated with AgN03, and the second flask is used for control. [...]

In addition to calcium and magnesium chlorides, the composition of salts dissolved in water present in the raw material contains sodium chloride, which, as is known, does not undergo hydrolysis, but significantly increases the conductivity of the corrosive environment and thereby increases its aggressiveness. On the other hand, it contributes to the development of pitting corrosion and corrosion cracking of austenitic steels, since, as well as the chlorides of magnesium and calcium, is a supplier of chlorine ions. This is what explains, in our opinion, the anomalously high corrosion rates of the upper plates of the column, made of 12X18H10T steel in 1997, when forced installation shutdowns became frequent, and oil with a high content of chlorides and water came to the plant. As shown in the reports of the chief process engineer of the plant, after only a few days of operation of the column under the conditions of the formation of an abnormally high HC1 content, the depth of damage of these elements reached 0.5 mm. Thus, the applied methods of protection (inhibition, neutralization and use of plates made of steel 12X18H10T) could not lead to an adequate level of reliability of operation of the apparatus. The use of a protective cap made of steel 08Kh17N13M2T can only be considered a temporary measure, since this steel, although to a lesser extent than 12X18H10T, is still subject to pitting corrosion under the action of chlorides, especially in an acidic environment. [...]

Rio.35. The influence of the content of A1SC on the pH value and the yield of active chlorine in solutions with a chloride content of 0.427 g-ion / l: I is the yield of active chlorine. 2 - voltage, 3 - pH of the initial electrolyte, 4 - pH of the electrolyte after electrolysis. [...]

In drinking water, the content of chlorides should not exceed 30-50 mg / l, and the content of sulphates - 60 mg / l. However, this is not always achievable in some southern low-water areas of our country (Turkmenistan, Kazakhstan, etc.), where local water sources are highly mineralized. [...]

According to GOST, the limiting content of sulfate ions in the water of sources of centralized water supply should not exceed 500 mg / l, but, as a rule, the concentration of sulfates in river water is 100-150 mg / l. An increased concentration of sulphates may indicate contamination of the source with wastewater, mainly industrial. Chlorides are an integral part of most natural waters. The content of chlorides of natural origin has a large range of fluctuations: However, the concentration of chlorides in the water of rivers is low - it usually exceeds 10-30 mg / l, therefore, an increased amount of chlorine ions indicates pollution of the source with wastewater. In water sources of centralized water supply, the concentration of chlorides should not exceed 350 mg / l. The limitation of the upper limit of sulfate and chloride concentrations is due to the fact that higher concentrations of these ions give the water a salty taste and can cause a disturbance in the gastrointestinal tract in humans. At some ratios of sulfates and chlorides, the water becomes aggressive towards various types of concrete. Silicates in solution are determined only in those natural waters where their content depends on geological conditions and the presence of certain organisms. All of these acids at ordinary for natural waters pH values ​​are slightly soluble and form colloidal solutions in water. Silicates are an undesirable impurity in the water that feeds the boilers, as it gives silicate scale on the walls of the boilers. [...]

The course of determination. Several glass beads are introduced into the flask, connected to a reflux condenser, the contents of the flask are heated to a boil, and boiled for 2 hours. At the same time, a single determination is made by taking 25 ml of water twice distilled (with the addition of permanganate in a boiling flask) of water. After cooling, the analyzed solution is transferred to a measuring flask with a capacity of 200 ml, the walls of the flask are washed twice with distilled water. Wash - water is poured into the flask and the test solution is brought to the mark with the same water. After taking an aliquot in 100 ml of the resulting solution, transfer it into a glass with a capacity of 400-450 ml, dilute with distilled water to about 300 ml and neutralize with 45% sodium hydroxide solution: first pour 30 ml of this solution, then add it dropwise after stirring to pH = 5-7. The neutralized solution is heated to boiling, 0.1 g of calcined magnesium oxide is introduced, and -; warm for 20 minutes at a low boil. Allow the precipitate to collect at the bottom of the glass and filter the solution through a dense filter, transferring the precipitate to the filter by the end of filtration. The filter cake is washed with hot water to obtain a colorless filtrate. The funnel with the filter is placed on a small conical flask, a hole is made in the filter, and the precipitate is washed through it with hot water into the flask. Then the filter is treated with 3 ml of 2N. sulfuric acid, washing it pre-wall glass. The filter and the glass are well washed with hot water, collecting the washings in the same flask and boil the contents of the flask until the precipitate is completely dissolved. The resulting solution is transferred to a volumetric flask with a capacity of 100 ml, filtering it, if necessary, through a dense filter. Then poured 5 ml 2 n. acetic acid and the mixture is boiled for 5 minutes. Cool the obtained colored solution, dilute it with distilled water to the mark, mix and measure its optical density at X = 536 nm in a cuvette with an absorbing layer thickness of 5 cm with respect to the blank solution. [...]

Samples for analysis on the content of organic substances were collected in hexane-washed glass bottles with a capacity of about 4 liters, equipped with Teflon corks. Samples for the determination of chlorides and suspended solids were taken in clean polyethylene liter vessels. All samples were stored at 4 ° C until analysis or extraction. Analyzes and extraction of suspended solids were carried out 36 hours after sampling. [...]

High solubility of chlorides explains their wide distribution in all natural waters. In flowing waters, the chloride content is usually low (20–30 mg / l). Unpolluted groundwater in places with unsolonced soil usually contain up to 30-50 mg / l of chlorine ion. In the waters filtered through saline soil, 1 l can contain hundreds and even thousands of milligrams of chlorides. Water containing chlorides in a concentration of more than 350 mg / l, has a salty taste, and at a chloride concentration of 500-1000 mg / l adversely affects gastric secretion. The chloride content is an indicator of pollution of underground and surface water sources and wastewater. Determination of chlorides is carried out according to the Mohr method. [...]

It is known that with increasing content of chlorides and sulphates in paper, with decreasing pH value, the corrosive action of paper increases. [...]

Advance directives. If the content of chlorides in a given volume of water exceeds 25 mg C1, then it is necessary to add mercury sulfate. If other inorganic reducing agents are present in water, they should be corrected for their oxygen consumption, which is set in 20 ml of the water under study by titrating it with a 0.0S solution of permanganate in a weakly acidic environment in the cold (see “Determination of permanganate oxidation”). [...]

The method is used to determine chlorides with a content of more than 2 mg / l without dilution. Samples with chloride content up to 400 mg / l can be titrated. Accuracy of determination is + 1- ■ 3 mg / l. For accurate determination of chlorides at concentrations of less than 10 mg / l, samples must be evaporated beforehand. Depending on the concentration of chlorides in the sample is titrated with 0.1 N., 0.05 N. or 0.02 n. silver nitrate solution. [...]

The presence in the wastewater of a large amount of chlorides adversely affects the process of ion-exchange wastewater treatment. The consequence of a high concentration of chlorine ions ¡in wastewater is a low concentration of non-cal in the regenerate and high expenditure of energy resources for its processing. The content of chlorides in wastewater leads to a decrease in the absorption capacity of the ion exchanger. [...]

In the analysis of cellulose containing a significant amount of chlorides, white bloom may form in the flask. In this case, the dried extract is dissolved in 15 ml of hot alcohol, 30 ml of distilled water is added, and the chloride content is determined by titration with 0.1 n. AgNO3 solution, using K2CY4 as an indicator. [...]

In the production of potassium nitrate waste is the brine with the content of sodium chloride 220-250 g / l. With the introduction of sodium chloride utilization at the plant (Fig. 1.12), the content of the latter in the total stock decreased from 4800 to 1200 mg / l. In this case, over 3,500 tons of sodium chloride are annually utilized, 40% of which is produced in the form of reactive purity chemical products. [...]

Meanwhile, calculations of changes in salt content, in particular, the content of chlorides and hardness salts, confirmed the reduction of scale formation by a factor of 8–9, i.e., about the same time as in bench tests. [...]

The influence of a low-molecular-mass electrolyte (sodium chloride) on the п potential is also studied. With an increase in the sodium chloride content to 1.5 g / l and the addition of a flocculant, the negative ■ ■ potential dropped sharply. With a further increase in the sodium chloride content in the wastewater, the decrease in the п potential was slowed down, the optimal dose of flocculant increased, and the cleaning efficiency deteriorated. This is due to a decrease in the degree of dissociation of ionogenic groups of the flocculant, coagulation of macromolecules and a decrease in their total positive charge. [...]

In a number of industries, liquid and solid wastes are formed with a high concentration of sodium chloride, as well as organic and organochlorine compounds. When firing these wastes, a product with a high content of sodium chloride can be obtained, suitable for further use. [...]

Biochemical oxidation of 2,4-D occurs with the formation of chlorine ions, and the increase in chloride content in samples corresponds to the amount of chlorine ions, which is contained in 2,4-D and is released during the oxidation process. [...]

This standard applies to drinking water and establishes methods for determining the content of chlorides (chlorine ion). [...]

The main indicators for the characteristics of the composition of treated wastewater are: the residue of oil or oil products in water (in mg / l), the content of suspended substances by weight, dried at a temperature of 105 ° C (in mg / l). amount of dissolved oxygen (in mg / l), transparency (in cm), color (in hail), color, content of chlorides and hydrogen sulfide (in mg / l), oxidability (in mg02 / l), active pH reaction, biochemical (VPK ) or chemical (COD) oxygen demand (in mg02 / l). In special cases, it may be of interest to determine the content of sulfates and sulfides (in mg / l). Additional indicators are moisture and ash content of the sediment (in%). Determination of sediment moisture should be done at least once a month. [...]

To date, groundwater quality is characterized as follows. In the quaternary horizon in industrial zones the content of chlorides, sulfates, dry residue and nitrates increased, the concentration of the latter exceeds 50 mg / dm3. [...]

The main problems of coal basins are the purification of acid and mineralized wastewater from the Urals deposits and waste waters with a high content of chlorides and sulphates of the Moscow suburbs, the elimination of small boilers and land reclamation for fields in Eastern Siberia - mine water and household water, land reclamation, for fields The Far East - the construction of wastewater treatment plants for mine and quarry water containing hard-to-disperse suspended sediment, increasing the efficiency of structures and land reclamation. [...]

According to Table 21, the required accuracy of dosing + 10% can be obtained when taking into account two options for the ionator: when working on waters that do not require the addition of sodium sulfate (about chloride content less than 10 to the anions), the preparation mode of 20 l concentrate - 6 min electrolysis at 3 A ;, when working with the addition of sodium sulfate, the cooking mode is 7 min electrolysis with a current of 3.2-3.4 A. [...]

Depending on the results of the qualitative determination, 100 cm3 of test water or a smaller volume (10-50 cm3) is taken and adjusted to 100 cm3 with distilled water. Chlorides in concentrations up to 100 mg / dm3 are determined without dilution. The pH of the titrated sample should be between 6-10. If the water has a color greater than 30 °, the sample is discolored by the addition of aluminum hydroxide. For this, 6 cm3 of aluminum hydroxide suspension are added to 200 cm3 of the sample, and the mixture is shaken until the liquid is decolorized. Then the sample is filtered through an ashless filter. The first portions of the filtrate are discarded. A measured volume of water is added to two conical flasks and 1 cm3 of potassium chromate solution is added. One sample is titrated with a solution of silver nitrate until a faint orange tint appears; the second sample is used as a control sample. With a significant content of chlorides, a precipitate of A SL is formed that interferes with the determination. In this case, 2-3 drops of the NaCi1 titrated solution are poured into the titled first sample until the orange color disappears, then the second sample is titrated, using the first one, as a control sample. [...]

The quality control of the water in the seasonal regulation tank constantly shows an increased level of mineralization of these waters, which often exceeds the standards by 20–40% and is conditioned. excess sodium chloride. The main source of it in wastewater is the regeneration solution, which is used to wash the ion exchange filters of the boiler room. [...]

The observed insignificant decrease in the amount of hemoglobin in experimental animals on the 4th month of experience compared with the control is statistically unreliable. The content of chlorides and reserve alkalinity in the blood, as well as the chlorides in the urine did not change during the whole study period. [...]

Many representatives of the largest family in the family of the parniferus, numbering about 100 species, are halophytes. They inhabit salt marshes mainly in Asia, Africa and Australia. This shrub has small fleshy leaves and develops a powerful taproot that penetrates to moist soil horizons. [...]

It is known that excessive salinity of the soil is characteristic of many mining areas around the world. In the German Democratic Republic, this is mainly the result of copper, slate, potash, brown coal, and soda production. Large amounts of chlorides and salts, which increase the hardness of the water, enter rivers with low or medium discharge, the water of which is used for industrial purposes by many large commercial enterprises. Even after absorption of these salts by the river (in the Elbe, for example, in the area of ​​Magdeburg, the average annual chloride content was 77–423 mg / l and 9.9–20.5 ° of total hardness) over the past 20 years, the harmful effects still remain significant, as can be demonstrated in the following examples. [...]

The quantitative ionometric rapid method for the determination of nitrates consists in extracting nitrates from the material with a solution of aluminum-potassium alum and then measuring the nitrate ion in the extract with an ion-selective electrode. The method is unsuitable for the study of products in which the content of chlorides exceeds the content of nitrates by more than 50 times. This method can only be used for the analysis of raw materials. [...]

There are reports of the occurrence of gastroenteritis of non-bacterial origin in Essen (Germany) in 1959, which affected about 7% of the population (K. Im-hoff, 1970). The reason was that the arid summer of 1959 caused a significant reduction in the flow of water in the River Ruhr. This reduced the river's ability to dilute wastewater. The content of chlorides in water increased from 100 to 507 mg / l, nitrates - to 24 mg / l, detergents - to 1.2 mg / l. The frequency of river water reuse was 0.9, which exceeds the allowable limit (N. Koenig et al 1970). [...]

Known and found partial application in foreign practice and the method of spraying OBR on arable land after its preliminary neutralization. However, the use of this method is limited to the type and processing system of the drilling fluid. This method is not suitable for mineralized drilling fluids, te, solutions with a high content of chlorides and other toxic salt components. But the absence in the literature of information about neutralizing agents does not allow an objective assessment of the possibilities of the method, as well as practical and economic feasibility of its use. [...]

Toxic substances of the most diverse action are known; however, when they enter the water, they behave mostly as common tortoises. Some external signs and data from conventional control methods may indicate that water is contaminated with toxic substances, since the presence of chemical agents causes changes in many water parameters, such as pH, oxidability, chlorine absorption, chlorine and dissolved oxygen, as well as biological and bacteriological studies. Therefore, all these indicators in the conditions of possible poisoning of the water of organic substances should be determined and recorded systematically. [...]

When hydrochloric acid etching of steel, the interaction of 20% acid with iron oxides leads to the formation of chloride and ferric chloride. Output to regenerate OTP contains,%: 5-10 HG1, 17-25 FeCl2, 0.4-0.8 FeClj. In multistage installations with a countercurrent of the metal being treated and the pickling solution in the latter, a very low acid concentration and a very high content of iron chlorides (up to 340 g / l) can be obtained. The regeneration products are hydrochloric acid, returned to the pickling bath, and iron oxide. [...]

The main type of pollution is ore and limestone dust. When water comes in contact with the sludge, leaching of lime and other components occurs, as a result of which the salt composition of wastewater undergoes significant changes. Studies have shown that the pH of water increases from 7.5 to 12-13, alkalinity from 1.3-3.6 to 21-22 mEq / dm3, including hydrate from zero to 17 mEq / dm3. The content of chlorides and sulphides also increases. [...]

Significant amounts of groundwater are polluted by a leachate-filtrate filtrate released from landfills of municipal solid waste. According to official data, only in the city limits in Moscow there are more than 100 dumps, and the “midnight” ones have never been counted. The composition of the filtrate can be approximately as follows and almost close to all landfills: increased to 10-20 g / l of mineralization, high contents of chlorides and sulphates, a variety of organic acids (humic, lactic, acetic, pyro-grape, etc.), the so-called " hurricane "concentrations of heavy metals (including the most toxic, such as mercury), drug, hospital and sanitary, bacteriological and gel contamination. It is known that active processes of fermentation and decay take place in the landfill, i.e., decomposition of organic matter, the final product of which is water, heat, biogas (carbon dioxide and carbon and methane). There are frequent cases of spontaneous combustion of biogas with negative environmental consequences, since many landfills are saturated with synthetic plastics, the burning of which in a low-temperature regime leads to the formation of dioxins entering the atmosphere, into the hydrosphere, and further into trophic ecosystem networks. [...]

The process is implemented in countercurrent mode in a scrubber-type reactor at 400 ° C. Its products are gas (about 7% HCl, 40 - water vapor, 0.8-1.0% 02) and iron oxide. The bulk of the latter settles in the solution, is separated from it, and is shipped to the consumer: The gas is cleared of residual Fe203, cooled and sent to an absorption column, irrigated with water from the washing baths. From its lower part, 16–20% hydrochloric acid is removed with a small, about 2%, content of iron chlorides. The gas after the absorption column is freed from residues of hydrogen chloride and other impurities in the scrubber, irrigated with caustic soda solution (NaOH), and is released into the chimney. [...]

Water with a dry residue of up to 1000 mg / l is called fresh, more than 1000 mg / l is mineralized. Water containing excessive amounts of mineral salts is not suitable for drinking, because has a salty or bitter-salty taste, and its use (depending on the composition of salts) leads to various unfavorable physiological abnormalities in the body. On the other hand, low-mineralized water with a dry residue below 50-100 mg / l does not taste good, prolonged use may also lead to some unfavorable physiological changes in the body (a decrease in the content of chlorides in tissues, etc.). Such water, as a rule, contains little fluorine and other trace elements. [...]

Data relating to the oxidation-reduction potential of the samples were obtained only for the spring of 1976. The waters of the well 12B were investigated; the redox potential there varied from +100 to +150 mV (maximum + 170 mV). Unexpectedly, the lowest values ​​(+ 55 and + 65 mV) were recorded in wells 10 and 4, respectively. Water well 7 had a redox potential of +105 mV. An increase in the oxidation-reduction potential from +90 mV (measured upstream) to +107 mV (measured downstream) was observed in the creek. With the exception of the summer and autumn analysis of the blasting from the well 6A, there is a general tendency for the chloride content to decrease with increasing distance from the treatment plant. The waters of the well 3 and the seepage below the road are characterized by a high chloride content, reflecting the salt intake from the road, as noted earlier. In all cases, there was a slight increase in the chloride content in West Brook Creek due to seepage.

Water, passing through igneous rocks consisting of chlorine-containing minerals and salt-bearing deposits, dissolves chlorides, that is, salts of hydrochloric acid, which are most often found in the form of sodium, magnesium and calcium salts. Their large amount in the groundwater and artesian waters is caused not only by volcanic emissions, but also as a result of the circulation - saturation of precipitation during its passage through the soil and then exchange through the atmosphere with the ocean. An increased sodium content can be observed due to leaching of soluble compounds with chlorine or sodium chloride from layers that come in contact with water. Therefore, it becomes unsuitable for economic and technical needs, or for irrigation in agriculture. Therefore necessary water purification from sodium. It is clear that salt water has an increased maximum permissible concentration of salts of the chloride group, and their cation composition is sodium, which forms sodium chloride with chlorine, which ensures its salty taste. Consequently, sodium enters the tap water in the following ways: passing through rocks and dissolving sodium carbonate, sulphate and chloride salts of sodium, from industrial and household wastewater, from irrigated fields. Most often, in all saline waters, sodium chloride is the most abundant relative to other salts, and therefore experts recommend installing. If magnesium chloride prevails, then it has a bitter-salty taste.

With excessive concentrations of chlorides and, respectively, sodium can be observed:

• irritation of the mucous membrane of the eyes, skin, respiratory tract;
• digestion is worsening and negatively affects the secretion of the stomach;
• in the body the water-salt balance is disturbed;
• circulatory system diseases may develop;
• there is a possibility of neoplasms of the urinary organs, stomach, esophagus and other digestive organs;
• gallstone and urolithiasis may occur;
• frequency of cardiovascular diseases increases.

Sodium water purification  It is necessary because the excessive content of chlorides, which is interconnected with an excess amount of sodium, is harmful for household equipment:

• corrosion of metal surfaces and parts of household appliances increases significantly;
• a precipitate appears on the heating elements of kettles, washing machines and dishwashers, boilers, which contributes to their premature failure.

Different trace elements are needed for each cell and for the whole body. Sodium is a trace element that plays an important role in the formation of gastric juice, with its participation, the excretion of human waste products by the kidneys is regulated. It promotes normal water-salt balance in the cells, normalizes neuromuscular activity. It ensures the preservation of soluble minerals in the blood and prevents the transfer of fluid from the blood vessels to the tissues adjacent to them. It is known that the human body is not adapted to independently produce sodium, therefore its supply must be replenished from various natural sources, for example, water. A balanced sodium content is provided by the kidneys. Excessive content can cause such diseases as hypertension, diabetes, neurosis. At the same time, there is an increased excitability, hyperactivity, impressionability, in some cases excessive thirst, sweating, and frequent urination are observed.

Sodium water purification  in living conditions is necessary if there is a surplus. In drinking water, the concentration of sodium should not exceed 200 mg / l. After all, its excess in the body contributes to an increase in blood pressure and, accordingly, the accumulation of fluid and the formation of edema, and also depletes the potassium reserves, which is necessary for the stable work of the cardiovascular system.

There are two main methods of salt water purification - the ion exchange method and. The ion-exchange method has the following advantages: obtaining high-quality water, the ability to work with a rapidly changing composition of the feed water, low energy and capital costs, low consumption for own needs, especially for counter-current filters. Disadvantages: a decent consumption of reagents, and as a result, an increase in operating costs in proportion to the salt content, depending on the composition of the source water, requires in some cases very complicated additional preparation.

Cleaning with the use of technology has many advantages: obtaining highly purified water, low energy consumption, performance is unlimited, reliability, low operating costs and membrane regeneration costs. Disadvantages: the need for careful additional water treatment, the continuity of equipment operation is required, but very significant capital expenditures on equipment.

The chemical composition of water is the cause of non-infectious diseases.

Reasons for changes in the chemical composition of water:

1) industrial and agricultural activity of a person - receipt of industrial and domestic wastewater, precipitation containing harmful substances.

2) purification of drinking water - the use of chemical methods of water treatment and the content of residual amounts of reagents in the water.

Indicators:

1. dry residue
2. rigidity
3. chlorides
4. sulfates
5. nitrates and nitrites
6. pH value
7. trace elements

Dry residue

The dry residue is the total content of dissolved solids in water, it gives an idea of ​​the degree of water salinity. The main ions determining the dry residue are carbonates, bicarbonates, chlorides, sulfates, nitrates, sodium, potassium, calcium, magnesium. This indicator affects other indicators of drinking water quality, such as taste, hardness, corrosive properties and scale buildup.

Water with a dry residue of more than 1000 mg / l is called mineralized, up to 1000 mg / l - fresh. Water containing up to 50 - 100 mg / l is considered to be slightly mineralized (distilled), 100 - 300 mg / l - satisfactorily mineralized, 300 - 500 mg / l - optimal mineralization and 500 - 1000 mg / l - increased mineralized. Mineralized water is sea, mineral, fresh - river, rainwater, glacier water.

The value of the dry residue:

1. Water with a high content of mineral salts is not suitable for drinking, as it has a salty or bitter-salty taste, and its use, depending on the composition of salts, leads to adverse physiological changes in the body:
   1. promotes overheating in hot weather,
   2. leads to a violation of thirst quenching,
   3. changes the water-salt metabolism due to an increase in tissue hydrophilicity,
   4. strengthens motor and secretory stomach and intestines.
2. Low-mineralized water has an unpleasant taste, its long-term use can lead to a violation of the water-salt metabolism (a decrease in the chloride content in the tissues). Such water, as a rule, contains few trace elements.

Rigidity

The overall hardness of water is mainly due to the presence of calcium and magnesium in water, which are in the form of hydrocarbons, carbonates, chlorides, sulfates and other compounds; ions of strontium, iron, barium, manganese are also important.

Types of stiffness:

1. Disposable - the value by which the total hardness of water decreases when boiling it for 1 hour. It is caused by calcium and magnesium bicarbonates, which break down and precipitate as carbonates in the sediment (scale).
2. Carbonate is the stiffness caused by bicarbonates and poorly soluble carbonates. The removable hardness is approximately equal to carbonate, but when there is a lot of sodium and calcium bicarbonates in water, the carbonate hardness considerably exceeds the removable one.
3. Permanent is the hardness that remains after boiling and is caused by chlorides, carbonates, and sulphates of calcium and magnesium.

Water with a total hardness of up to 3.5 mg-eq / l is called soft, 3.5-7 - medium hardness, 7-10 - hard, over-10 - very hard.

The main natural sources of water hardness are sedimentary rocks, filtration and runoff from the soil. Hard water is formed in areas with a dense topsoil and calcareous formations. Groundwater is characterized by greater rigidity than surface water. Underground waters rich in carboxylic acids and dissolved oxygen have a high dissolving ability with respect to soils and rocks containing the minerals of calcite, gypsum and dolomite.

The main industrial sources of stiffness are effluent from enterprises producing inorganic chemicals and the mining industry. Calcium oxide is used in the construction industry, the production of paper pulp and paper, sugar refining, oil refining, tanning and as a reagent for water and wastewater treatment. Magnesium alloys are used in foundry and stamping production, household products. Magnesium salts are used in the production of metallic magnesium, fertilizers, ceramics, explosives, and medicines.

The value of hard water:

Organoleptic properties deteriorate - water has an unpleasant taste;

The absorption of fats in the intestine is disturbed as a result of the formation of calcium-magnesian insoluble soaps during saponification of fats;

In individuals with sensitive skin, dermatitis is promoted due to the fact that calcium-magnesia soaps have an irritating effect.

In the household aspect: the consumption of detergents increases, scum forms when boiling, hair becomes hard after washing, clothing fabrics lose their softness and flexibility, and the digestion of meat and vegetables deteriorates with the loss of vitamins as a result of binding them to unassimilated complexes,

There is evidence that drinking too hard water can lead to an increase in the incidence of urolithiasis; although there is evidence that stiffness can serve as a defense against disease;

With a sharp transition from using hard water to soft water and vice versa, people can experience dyspepsia;

It spoils the look, taste and quality of tea, which is the most important drink among the population, stimulating gastric secretion and quenching thirst;

There is evidence that the use of soft water can cause cardiovascular diseases.

Chlorides

Chlorides can be of mineral and organic origin. The presence of chlorides in natural waters can be associated with the dissolution of salt deposits, pollution caused by salt deposited on the roads in order to control snow with ice, discharge of effluents by the chemical industry, operation of oil wells, discharge of wastewater, irrigation drainage, pollution due to leaching of solid waste and seawater intrusion into coastal areas. Each of these sources can cause pollution of surface and groundwater. High solubility of chlorides explains their wide distribution in all natural waters.

Impact on health. Chlorides are the most common anions in the human body and play a large role in the osmotic activity of extracellular fluid; 88% of the chlorides in the body are in the extracellular space. In healthy people, almost complete absorption of chlorides occurs.

Chloride value:

Organoleptic properties deteriorate - water gets a salty taste and, therefore, water consumption is limited;

Influences the water - salt metabolism; the level of chlorides in the blood rises, which leads to a decrease in diuresis and redistribution of chlorides in organs and tissues;

Cause depression of gastric secretion, as a result of which the process of digestion is disturbed;

There is evidence that chlorides have a hypertensive effect and in people suffering from hypertension, the use of water with an elevated content of chlorides may cause a worsening of the course of the disease;

They are an indicator of pollution of underground and surface water sources, since chlorides are contained in wastewater and human physiological secretions.

Sulfates

Sulfates enter the aquatic environment with wastewater from many industries. Atmospheric sulfur dioxide (SO2), which is formed during the combustion of fuel and released during roasting in metallurgy, may contribute to the sulfate content in surface waters. Sulfur trioxide (SO3), which is formed during the oxidation of sulfur dioxide, in combination with water vapor forms sulfuric acid, which falls in the form of "sour rain" or snow. Most sulphates are water soluble.

With aluminum sulphate, which is used as a flocculant for water purification, 20-50 mg / l of sulphate can be additionally treated water. Sulfates are not removed from water by conventional purification methods. Concentration in most fresh water is very low.

Sulphate value:

Sulfates are poorly absorbed from human intestines. They slowly penetrate the cell membrane and are rapidly excreted through the kidneys. Magnesium sulphate acts as a laxative at a concentration above 100 mg / l, leading to a cleansing of the digestive tract. This effect occurs in people who first use water with a high content of sulfates (when moving to a new place of residence, where they use sulphate water). Over time, the person adapts to this concentration of sulphate in water.

Water consumption is limited, as sulphates give the water a bitter-salty taste in concentrations above 500 mg / l.

Adversely affect gastric secretion, leading to disruption of the processes of digestion and absorption of food.

They are an indicator of surface water pollution by industrial wastewater and groundwater by overlying aquifers.

Nitrates, nitrites

Ammonia is the initial decomposition product of organic nitrogen containing substances. Therefore, the presence of ammonia in water can be regarded as an indicator of the danger of epidemically dangerous fresh water pollution with organic matter of animal origin. In some cases, the presence of ammonia does not indicate the poor quality of the water. For example: in deep groundwater, ammonia is formed due to the reduction of nitrates in the absence of oxygen or an increased content of ammonia in the marshy and peaty waters (ammonia of plant origin).

Nitrous acid salts (nitrites) are the products of partial oxidation of ammonia under the influence of microorganisms in the nitrification process. The presence of nitrites indicates a possible contamination of water with organic substances, however, nitrites indicate a known prescription of contamination.

Nitric acid salts (nitrates) are the final products of the mineralization of organic substances by bacteria present in the soil and in water with a sufficient oxygen content. The presence of nitrates in water without ammonia and nitrites indicates the completion of the mineralization process.

The simultaneous content of ammonia, nitrites and nitrates in water indicates the incompleteness of this process and the continuing, epidemically dangerous water pollution. However, an elevated nitrate content may be of mineral origin. Nitrates are used as fertilizers (nitrate), in explosives, in chemical production and as preservatives in food. Some nitrates are the result of fixation of atmospheric nitrogen in the soil (bacterial synthesis). Nitrite is used as a food preservative. Some nitrates and nitrites are formed when rain leaches out nitrogen oxides, which are the result of lightning strikes or come from anthropogenic sources.

Nitrates and nitrites are widespread in the environment, they are found in most food products, in the atmosphere and in many water sources. The use of fertilizers, decay of plant and animal material, domestic sewage, removal of sewage sludge into the soil, industrial discharges, leaching from waste disposal sites and leaching from the atmosphere contribute to the entry of these ions into the water. In natural clear waters, nitrates, as a rule, are few. However, in groundwater within settlements, livestock farms and in other places where the soil is long and massively polluted, the nitrate content can be high.

Since none of the commonly used methods of cleaning and disinfecting water significantly changes the level of nitrates, and since the concentration of nitrates does not change significantly in the water distribution system, the levels in tap water are often completely similar to those for water sources. The content of nitrites in tap water is lower than in water sources, which is caused by their oxidation during water treatment, especially during chlorination.

Metabolism. Nitrates and nitrites are easily absorbed by the body. Nitrates are absorbed in the upper portions of the small intestine, are concentrated mainly in the saliva through the salivary glands, excreted through the kidneys. Nitrate can easily turn into nitrite as a result of bacterial reduction. The reduction of nitrates to nitrites occurs throughout the body, including the stomach. This conversion is dependent on the pH value. In infants whose acidity in the stomach is normally very low, a large amount of nitrite is formed. In adults, the acidity in the stomach is characterized by a pH value of 1-5 and to a lesser extent nitrate is converted to nitrite. Nitrite can oxidize hemoglobin to methemoglobin. Under certain conditions, nitrites can react in the human body with secondary and tertiary amines and amides (food) to form nitrosamines, some of which are considered carcinogenic.

The value of nitrates, nitrites:

Cause the development of "water-nitrate methemoglobinemia" due to the oxidation of hemoglobin by nitrites to methemoglobin. Mostly this disease occurs in children. The sensitivity of infants to the action of nitrates was attributed to their high intake relative to body weight, the presence of nitrate-reducing bacteria in the upper GI tract and easier oxidation of fetal hemoglobin. In addition, increased sensitivity is observed in infants suffering from impaired gastrointestinal function, which increases the number of bacteria capable of converting nitrates to nitrites. The use of artificial mixtures for feeding children is also considered as a reason for increasing the incidence, since the water used to prepare the mixture may contain an increased amount of nitrates. In infants in the stomach, a pH value close to neutral promotes bacterial growth in the stomach and in the upper intestines. In children, there is a deficiency in two specific enzymes that reverse the transformation of methemoglobin into hemoglobin. Prolonged boiling can aggravate the problem due to an increase in the amount of nitrates when water evaporates. The most common cause of the disease was the use of private wells with microbiological contamination as a source of water (they lack algae that actively consume nitrates). The disease is characterized by the development of dyspnea, cyanosis, tachycardia, seizures. In children older than 1 year and adults, the disease in the form of acute toxic cyanosis is not observed, but the content of methemoglobin in the blood increases, which worsens the transport of oxygen to the tissues - this is manifested by weakness, pallor of the skin, and increased fatigue.

They cause the formation of nitrosamines, some of which may be carcinogenic. The formation of these substances occurs in the mouth or elsewhere in the body, where the acidity is relatively low.

They are an indicator of water pollution by organic matter.

PH value (active reaction).

Marshy waters containing humic substances are acid, groundwater rich in bicarbonates is alkaline.

Value:

Determines the natural properties of water;

It is an indicator of contamination of open water bodies when acidic or alkaline industrial wastewater is discharged into them;

The pH value is closely related to other indicators of drinking water quality. The growth of iron bacteria is largely pH dependent. They form as the final product of metabolism iron oxide hydrate, which gives red color to water. At high pH values, the water gets a bitter taste.

The effectiveness of coagulation and disinfection processes is pH dependent. The disinfecting effect of chlorine in water is lower at high pH values; This is due to a decrease in the concentration of hypochlorous acid.

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Traditionally, water quality indicators are divided into physical (temperature, color, taste, odor, turbidity, etc.), chemical (pH of water pH, alkalinity, hardness, oxidability, general mineralization (dry residue), etc.) and sanitary and bacteriological (general bacterial contamination of water, coli index, the content of toxic and radioactive components in water, etc.).

To determine how much water meets the required standards, the numerical values ​​of water quality indicators are documented, with which the measured indicators are compared.

The regulatory and technical literature that constitutes water and sanitary legislation imposes specific requirements on the quality of water, depending on its purpose. Such documents include GOST 2874-82 “Drinking Water”, SanPiN 2.1.4.559-96 “Drinking Water”, “Drinking Water. Hygienic requirements for water quality in centralized drinking water supply systems ”, SanPiN 2.1.4.1116-02“ Drinking water. Hygienic requirements for the quality of water packaged in containers. Quality control ”, SanPiN 2.1.4.1175-02“ Hygienic requirements for the quality of decentralized water supply. Sanitary protection sources.

According to SanPin requirements, drinking water must be harmless in its chemical composition, radiation and epidemiologically safe, and have a pleasant taste and smell. Therefore, to maintain your own health, it is so important to know what kind of water you drink. To do this, it must be submitted for analysis - check how well the water meets the requirements of sanitary norms and rules.

Let us consider in detail the parameters by which water quality is assessed.

Physical indicators of water quality

Water temperature  surface sources is determined by air temperature, its humidity, speed and nature of water movement (as well as a number of other factors). Depending on the season, it may undergo significant changes (from 0.1 to 30º С). For underground sources, the water temperature is more stable (8-12 º C).

The optimum water temperature for drinking purposes is 7-11 ºС.

It is worth noting that this water parameter is of great importance for some industries (for example, for cooling systems and steam condensation).

Turbidity  - an indicator of the content in water of various suspended substances (mineral origin - particles of clay, sand, silt; inorganic origin - carbonates of various metals, iron hydroxide; organic origin - plankton, algae, etc.). The ingress of suspended substances into the water occurs as a result of the erosion of the banks and bottom of the river, their entry with melt, rain and sewage.

Underground sources have, as a rule, a small turbidity of water due to the presence in it of a suspension of iron hydroxide. For surface waters, turbidity is often caused by the presence of zoo and phytoplankton, oozy or clay particles; its value fluctuates throughout the year.

Turbidity is usually expressed in milligrams per liter (mg / l); its value for drinking water according to the norms of SanPiN 2.1.4.559-96 should not exceed 1.5 mg / l. For a number of productions of the food, medical, chemical, electronic industry water of the same or higher quality is used. At the same time, in many production processes, the use of water with a high content of suspended substances is permissible.

Water color  - an indicator characterizing the intensity of water color. It is measured in degrees on a platinum-cobalt scale, while the water sample under investigation is compared in color with reference solutions. The color of water is caused by the presence of impurities of both organic and inorganic nature. The presence of organic substances washed out from the soil (humic and fulvic acids, mainly) strongly influences this characteristic; iron and other metals; industrial pollution from industrial wastewater. SanPiN requirement 2.1.4.559-96 - the color of drinking water should be no more than 20º. Certain types of industry are tightening the requirements for the color of water.

Smell and taste of water  - this characteristic is determined organoleptically (using the senses), so it is quite subjective.

Smells and smack, which water may have, appear due to the presence of dissolved gases, organic substances, mineral salts, and chemical man-made pollutants. The intensity of smells and tastes are determined on a five-point scale or on the “dilution threshold” of the test water sample with distilled water. This sets the multiplicity of dilution required for the disappearance of odor or taste. Determination of smell and taste occurs by direct tasting at room temperature, as well as at a temperature of 60 º C, causing their enhancement. Drinking water at 60º С should not have a taste and smell more than 2 points (requirements of GOST 2874-82).

In accordance with the 5-point scale: with 0 points - the smell and taste is not detected;

at 1 point, water has a very faint odor or taste, found only by an experienced researcher;

at 2 points there is a faint odor or taste, which is also obvious to a layman;

at 3 points a noticeable odor or taste is easily detected (which is the reason for complaints about the quality of water);

at 4 points, there is a distinct smell or taste that can make you refrain from drinking water;

at 5 points water has such a strong smell or taste that it becomes completely unsuitable for drinking.

The taste of water is due to the presence of dissolved substances in it, which gives it a certain taste, which can be salty, bitter, sweetish and sour. Natural waters, as a rule, have only a salty and bitter taste. Moreover, a salty taste appears in water containing sodium chloride, and a bitter taste gives an excess of magnesium sulfate. Water with a large amount of dissolved carbon dioxide (the so-called mineral water) has a sour taste. Water with an ink or glandular taste is saturated with salts of iron and manganese; Calcium sulphate, potassium permanganate gives it an astringent taste; alkaline taste is caused by the content of soda in water, potash, alkali. The taste may be of natural origin (the presence of manganese, iron, methane, hydrogen sulfide, etc.) and artificial origin (when industrial waste is discharged). Requirements SanPiN 2.1.4.559-9 to drinking water - smack no more than 2 points.

Different living and dead organisms, plant residues, specific substances emitted by some algae and microorganisms, as well as the presence of dissolved gases in water, such as chlorine, ammonia, hydrogen sulfide, mercaptans, or organic and organochlorine impurities, give odors to water. Smells are natural (natural) and artificial origin. The first includes such smells as woody, aromatic, earthy, marsh, mold, putrefactive, herbaceous, fishy, ​​unspecified, and hydrogen sulfide, etc. Odors of artificial origin get their name after their determining substances: camphor, phenolic, chlorine, resinous, pharmaceutical, chlorine-phenol, the smell of petroleum products, etc.

Requirements SanPiN 2.1.4.559-9 to drinking water - the smell is not more than 2 points.

Chemical indicators of water quality

Total mineralization  (dry residue). Total mineralization is a quantitative indicator of substances dissolved in 1 l of water (inorganic salts, organic substances - except gases). This indicator is also called total salt content. Its characteristic is the dry residue resulting from evaporation of the filtered water and drying the delayed residue to constant weight. Russian standards allow mineralization of water used for drinking purposes, not more than 1000 - 1500 mg / l. The dry residue for drinking water should not exceed 1000 mg / l.

Active water reaction  (the degree of its acidity or alkalinity) is determined by the ratio of the acidic (hydrogen) and alkaline (hydroxyl) ions existing in it. When it is used, pH is used - hydrogen and hydroxyl indicators, determining, respectively, the acidity and alkalinity of water. The pH value of the pH is equal to the negative decimal logarithm of the concentration of hydrogen ions in water. With an equal amount of acid and alkaline ions, the reaction of water is neutral, and the pH value = 7. At pH<7,0 вода имеет кислую реакцию; при рН>7.0 - alkaline. SanPiN 2.1.4.559-96 standards require that the pH value of drinking water is in the range of 6.0 ... 9.0. Most natural sources have a pH value within the specified limits. However, it can cause a significant change in pH. Proper assessment of water quality and the exact choice of the method of its purification implies knowledge of the pH of water sources at different periods of the year. Water with low pH values ​​has a strong corrosive effect on steel and concrete.

Often water quality is described through the term hardness. The requirements for water quality in terms of hardness in Russia and Europe are very different: 7 mg-eq / l (according to Russian standards) and 1 mg-eq / l (Directive of the EU Council). Increased hardness is the most common water quality problem.

Hardness of water  - an indicator characterizing the content in water of hardness salts (mainly calcium and magnesium). It is measured in milligram equivalents per liter (mEq / l). There are such concepts as carbonate (temporary) hardness, non-carbonate (constant) hardness and total water hardness.

Carbonate hardness (disposable) is an indicator of the presence of calcium and magnesium bicarbonate in water. When water is boiled, it decomposes with the formation of poorly soluble salts and carbon dioxide.

Non-carbonate or constant hardness is determined by the content in water of non-carbonate salts of calcium and magnesium - sulfates, chlorides, nitrates. When boiling water, they do not precipitate and remain in solution.

Total hardness - the total amount of calcium and magnesium salts in water; is the sum of carbonate and noncarbonate hardness.

Depending on the magnitude of the hardness, water is characterized as:

The magnitude of water hardness varies considerably depending on what types of rocks and soils make up the catchment basin; on weather conditions and season of the year. So, in surface sources, water is usually relatively soft (3 ... 6 mg-eq / l) and depends on the location - the further south, the higher the hardness of the water. The hardness of groundwater varies depending on the depth and location of the aquifer layer and the value of the annual precipitation. In a layer of limestone, the water hardness is usually 6 mEq / L or more.

The hardness of drinking water (according to the norms of SanPiN 2.1.4.559-96) should not exceed 7.0 mg-eq / l.

Hard water due to excess calcium has an unpleasant taste. The danger of the constant use of water with increased rigidity is in reducing gastric motility, salt accumulation in the body, the risk of joint disease (arthritis, polyarthritis) and the formation of kidney stones and biliary tract. True, very soft water is also not useful. Soft water, which has great activity, is able to flush calcium from bones, which leads to their fragility; the development of rickets in children. Another unpleasant property of soft water is its ability to flush out useful organic substances as it passes through the digestive tract, including beneficial bacteria. The best option is water with a hardness of 1.5-2 mg-eq / l.

It is already well known that it is undesirable to use hard water for economic purposes. Effects such as plaque on plumbing fixtures and fixtures, scale formation in water heating systems and fixtures are obvious! The formation of calcium and magnesium salts of fatty acids in the domestic use of hard water leads to a significant increase in the consumption of detergents and slow down the process of cooking, which is problematic for the food industry. In some cases, the use of hard water for industrial purposes (in the textile paper industry, at artificial fiber enterprises, for feeding steam boilers, etc.) is prohibited due to undesirable consequences.

The use of hard water reduces the service life of water heating equipment (boilers, central water supply batteries, etc.). The deposition of hardness salts (bicarbonates Ca and Mg) on ​​the inner walls of the pipes, scale deposits in water heating and cooling systems reduce the flow area, reduce heat transfer. In systems of circulating water supply it is not allowed to use water with high carbonate hardness.

Alkalinity of water. The total alkalinity of water is the sum of the hydrates and anions of weak acids (silicic, carbonic, phosphoric, etc.) contained in it. In the characterization of groundwater, in most cases, hydrocarbonate alkalinity is used, that is, the content of hydrocarbonate in water. Alkalinity forms: bicarbonate, carbonate and hydrate. Alkalinity (mEq / l) is determined to control the quality of drinking water; to determine the suitability of water for irrigation; for the calculation of carbonate content, for subsequent wastewater treatment.

MPC for alkalinity 0.5 - 6.5 mmol / dm3.

Chlorides - their presence is observed in almost all waters. Their presence in water is due to leaching of sodium chloride (table salt), a very common salt on earth, from rocks. A significant amount of sodium chlorides is contained in sea water, as well as in the water of some lakes and underground sources.

Depending on the standard, the MPC of chlorides in drinking water is 300 ... 350 mg / l.

The increased content of chlorides with the simultaneous presence in the water of nitrites, nitrates and ammonia is found in the case of contamination of the source with domestic wastewater.

Sulfates  is present in groundwater as a result of the dissolution of gypsum present in the formations. When an excess of sulfates in water, a person develops an upset gastrointestinal tract (these salts have a weakening effect).

MPC of sulfates in drinking water is 500 mg / l.

Content silicic acid. Silicic acids of various forms (from colloidal to ion-dispersed) are found in the water of underground and surface sources. Silicon has a low solubility, and its content in water, as a rule, is small. Silicon entering the water also occurs with industrial effluents of enterprises engaged in the production of ceramics, cement, glass products, silicate paints.

Maximum concentration limit of silicon makes 10 mg / l. The use of water containing silicic acid is prohibited for feeding high-pressure boilers - due to the formation of silicate scale on the walls.

Phosphate  water is usually small, so their high content signals a possible contamination by industrial run-off or run-off from agricultural fields. With an elevated phosphate content, blue-green algae develop vigorously, releasing toxins into the water upon dying off.

MPC of phosphorus compounds in drinking water - 3.5 mg / l.

Fluorides  and iodides. Fluorides and iodides have some similarities. Lack or excess of these elements in the human body leads to serious diseases. For example, a deficiency (excess) of iodine provokes thyroid disease ("goiter") that develops when the daily ration of iodine is less than 0.003 mg or more than 0.01 mg. Fluorides are found in minerals - fluorine salts. Fluorine content in drinking water to maintain human health should be in the range of 0.7 - 1.5 mg / l (depending on climate).

Surface sources are mainly low in fluorine (0.3-0.4 mg / l). The fluorine content in surface waters increases due to the discharge of industrial fluorine-containing wastewater or when water comes into contact with soils rich in fluorine compounds. Thus, the artesian and mineral waters in contact with fluorine-containing water-bearing rocks have a maximum fluorine concentration of 5-27 mg / l and more. An important characteristic for human health is the amount of fluoride in its daily diet. Typically, the fluorine content in the daily diet is from 0.54 to 1.6 mg of fluorine (averaged 0.81 mg). It should be noted that 4-6 times less fluoride enters the human body with food than with drinking water, which has an optimum content (1 mg / l).

With an increased content of fluorine in water (more than 1.5 mg / l), there is a danger of developing in the population endemic fluorosis (the so-called "spotted tooth enamel"), rickets and anemia. These diseases are accompanied by a characteristic damage to the teeth, a violation of the processes of skeletal ossification, depletion of the body. Therefore, in drinking water fluorine content is limited. It is also a fact that some amount of fluoride in water is necessary to reduce the level of diseases determined by the effects of odontogenic infection (cardiovascular pathology, rheumatism, kidney disease, etc.). When drinking water with a fluorine content of less than 0.5 mg / l, tooth decay develops, therefore, in such cases, doctors recommend using fluoride toothpaste. Fluorine is better absorbed by the body from water. Based on the foregoing, the optimal dose of fluoride in drinking water is 0.7 ... 1.2 mg / l.

MPC of fluorine - 1.5 mg / l.

Permanganate oxidation  - parameter due to the presence of organic matter in water; In part, it can signal contamination of the source with wastewater. Depending on which oxidant is used when , the permanganate oxidability and bichromate oxidation (or COD - chemical oxygen demand) differ. Permanganate oxidizability is a characteristic of the content of easily oxidizable organic matter, bichromate - the total content of organic substances in water. The quantitative value of these indicators and their ratio allows us to indirectly judge the nature of organic substances present in water, as well as the methods and effectiveness of water treatment.

According to the requirements of SanPiN: the permanganate oxidation of water should not exceed 5.0 mg O 2 / l. Water with permanganate oxidation of less than 5 mg O 2 / l is considered clean, more than 5 mg O 2 / l is dirty.

In truly dissolved form (ferrous iron Fe2 +). Contained usually in artesian wells (no dissolved oxygen). The water is clear, colorless. If the content of such iron in it is high, then when settling or heating water becomes yellowish-brown;

In undissolved form (ferric iron Fe3 +) is contained in surface water sources. Transparent water - with brownish-brown sediment or pronounced flakes;

In the colloidal state or in the form of a fine suspension. The water is turbid, colored, yellowish-brown opalescent. Colloidal particles, while in suspension, do not precipitate, even after prolonged settling;

In the form of the so-called iron-organic - iron salts and humic and fulvic acids. The water is clear, yellowish-brown;

Iron bacteria that form brown mucus on water pipes.

The iron content in the surface waters of central Russia is from 0.1 to 1.0 mg / dm 3 of iron; in groundwater, this value reaches 15-20 mg / dm 3 and more. It is important to conduct an analysis of the iron content in the wastewater. The wastewaters of the metalworking, metallurgical, paint and varnish, textile, and agricultural sewage plants especially “litter” the reservoirs with iron. The concentration of iron in water is influenced by the pH and oxygen content of the water. In well and borehole water, iron can be in oxidized and reduced form, however, when water is allowed to settle, it is always oxidized and can precipitate.

SanPiN 2.1.4.559-96 allow a total iron content of not more than 0.3 mg / l.

It is believed that iron is not toxic to the human body, but with long-term use of water with excess iron content, the deposition of its compounds in human tissues and organs can occur. Water contaminated with iron, has an unpleasant taste, brings inconvenience in everyday life. At a number of industrial enterprises that use water for washing the product during its manufacture, for example, in the textile industry, even a small amount of iron in the water significantly reduces the quality of products.

Manganese found in water in similar modifications. Manganese is a metal that activates a number of enzymes involved in the processes of respiration, photosynthesis, and affects blood formation and mineral metabolism. With a lack of manganese in the soil, plants are observed chlorosis, necrosis, spotting. Therefore, manganese-poor soils (carbonate and re-limestone) are enriched with manganese fertilizers. For animals, the lack of this element in feed leads to slower growth and development, impaired mineral metabolism, and the development of anemia. The man suffers from both deficiency and an excess of manganese.

Norms SanPiN 2.1.4.559-96 allow manganese content in drinking water to not more than 0.1 mg / l.

A surplus of manganese in water can cause disease of the human skeletal system. Such water has an unpleasant metallic taste. Its long-term use leads to the deposition of manganese in the liver. The presence of manganese and iron in water contributes to the formation of glandular and manganese bacteria, whose waste products in pipes and heat exchangers cause a reduction in their cross section, and sometimes their complete blockage. Water used in the food, textile industry, in the production of plastics, etc., must contain a strictly limited amount of iron and manganese.

Also, a surplus of manganese leads to staining of linen during washing, the formation of black spots on plumbing and dishes.

Sodium  and potassium  - ingress of these elements into groundwater occurs in the process of dissolution of bedrock. The main source of sodium in natural waters is deposits of sodium chloride NaCl, which originated at the locations of ancient seas. Potassium in the water is less common - due to its absorption by soil and plants.

Sodium  plays an important biological role for most life forms on Earth, including man. The human body contains approximately 100 g of sodium. Sodium ions fulfill the task of activating enzymatic metabolism in the human body.

According to the norms of SanPiN 2.1.4.559-96 MAC of sodium - 200 mg / l. Excess sodium in water and food provokes the development of hypertension and hypertension in humans.

Potassium helps to enhance the excretion of water from the body. This property is used to facilitate the functioning of the cardiovascular system in case of its insufficiency, disappearance or significant reduction of edema. A lack of potassium in the body leads to impaired neuromuscular functions (paralysis and paresis) and the cardiovascular system and contributes to depression, discoordination of movements, muscular hypotension, seizures, arterial hypotension, changes in the ECG, nephritis, enteritis, etc. mg / l.

Copper, zinc, cadmium, arsenic, lead, nickel, chromeand   mercury  - ingress of these elements into water supply sources occurs predominantly with industrial effluents. An increase in copper and zinc content may also be a consequence of corrosion of galvanized and copper water pipes in the event of an increased content of aggressive carbon dioxide.

According to the norms of SanPiN, the MPC of these elements is: for copper - 1.0 mg / l; zinc - 5.0 mg / l; lead - 0.03 mg / l; cadmium - 0.001 mg / l; nickel - 0.1 mg / l (in the EU countries - 0.05 mg / l), arsenic - 0.05 mg / l; Cr3 + chromium - 0.5 mg / l, mercury - 0.0005 mg / l; Cr4 + chromium - 0.05 mg / l.

All these compounds are heavy metals with a cumulative effect, that is, they tend to accumulate in the body.

Cadmium  very toxic. Accumulation of cadmium in the body can lead to diseases such as anemia, damage to the liver, kidneys and lungs, cardiopathy, pulmonary emphysema, osteoporosis, skeletal deformity, hypertension. The excess of this element provokes and increases the deficiency of Se and Zn. Symptoms of cadmium poisoning are damage to the central nervous system, protein in the urine, acute bone pain, and dysfunction of the genital organs. All chemical forms of cadmium are dangerous.

Aluminum  - Lightweight silver-white metal. First of all, its penetration into water occurs in the process of water treatment - as part of coagulants and when discharging wastewater from bauxite processing.

In water, the MPC of aluminum salts is 0.5 mg / l.

With an excess of aluminum in the water, damage to the human central nervous system occurs.

Boron  and selenium  - the presence of these elements in some natural waters is found in very insignificant concentrations. It must be remembered that their increased concentration leads to serious poisoning.

Oxygen resides in water in dissolved form. There is no dissolved oxygen in groundwater. Its content in surface waters depends on the water temperature, and is also determined by the intensity of the enrichment or depletion of water with oxygen, reaching up to 14 mg / l.

Even significant content   oxygen  and carbon dioxide  does not impair the quality of drinking water, while at the same time contributing to increased corrosion of the metal. Increasing the temperature of the water and its mobility increase the corrosion process. The increased content of aggressive carbon dioxide in water makes the walls of concrete pipes and tanks susceptible to corrosion. The presence of oxygen is not permissible in the feed water of medium and high pressure steam boilers. Hydrogen sulphide  tends to give the water a characteristic unpleasant odor and cause corrosion of the metal walls of boilers, tanks and pipes. Because of this, hydrogen sulfide is not allowed to be in drinking water and water for most industrial needs.

Nitrogen compounds.  Nitrogen-containing substances include nitrite  NO 2 -, nitrates  NO 3 - and ammonium salts  NH 4 +, almost always present in all waters, including groundwater. Their presence indicates that there are organic substances of animal origin in the water. These substances are formed as a result of the decomposition of organic impurities, mainly urea and proteins, which enter the water with domestic wastewater. The group of ions under consideration is closely related.

The first decay product is ammonia (ammonium nitrogen)It is formed as a result of the breakdown of proteins and is an indicator of fresh fecal contamination. The oxidation of ammonium ions to nitrates and nitrites in natural water is carried out by the bacteria Nitrobacter and Nitrosomonas. Nitrites  - The best indicator of fresh faecal contamination of water, especially if the content of ammonia and nitrite is increased at the same time. Nitrates  - an indicator of more old organic fecal pollution of water. The nitrate content together with ammonia and nitrite is unacceptable.

Thus, the presence, amount and ratio of nitrogen-containing compounds in water allows us to judge how strongly and for how long the water has been contaminated with human waste products. In the absence of ammonia in the water and, at the same time, the presence of nitrites and especially nitrates, we can conclude that the reservoir has been polluted for a long time, and during this time the water has been self-cleaning. If ammonia is present in the pond and there is no nitrate, then water pollution with organic matter has happened recently. Ammonia and nitrite are not allowed in drinking water.

MPC in water: ammonium - 2.0 mg / l; nitrites - 3.0 mg / l; nitrates - 45.0 mg / l.

If the concentration of ammonium ion in water exceeds the background values, it means that pollution has occurred recently, and the source of pollution is close. These may include livestock farms, municipal wastewater treatment plants, accumulations of nitrogen fertilizers, manure, settlements, industrial waste settlers, etc.

When drinking water with a high content of nitrates and nitrites in humans, the oxidative function of the blood is impaired.

Chlorine  is introduced into the drinking water with her. Chlorine exhibits a disinfecting effect, oxidizing or chlorinating (replacing) the molecules of substances that are part of the cytoplasm of bacterial cells, causing the bacteria to die. The causative agents of dysentery, typhoid, cholera and paratyphoid are extremely sensitive to chlorine. Relatively small doses of chlorine disinfect even heavily contaminated water. However, there is no complete sterilization of water due to maintaining the viability of individual chlorine-resistant individuals.

Free chlorine  - a substance harmful to human health, therefore in drinking water of the centralized water supply, the SanPiN hygiene standards strictly regulate the content of residual free chlorine. SanPiN sets the upper and minimum allowable limits for the content of free residual chlorine. The problem is that, although water is decontaminated at a water treatment plant, it is at risk of secondary contamination on its way to the consumer. For example, there may be fistulae in a steel underground highway, through which soil contaminants enter the main water.

Therefore, the norms of SanPiN 2.1.4.559-96 provide for the content of residual chlorine in tap water to be not less than 0.3 mg / l and not more than 0.5 mg / l.

Chlorine is toxic and is a strong allergy, so chlorinated water has an adverse effect on the skin and mucous membranes. These include reddening of various skin areas, and manifestations of allergic conjunctivitis (swelling of the eyelids, burning, tearing, pain in the eye area). Chlorine also adversely affects the respiratory system: as a result of staying in the pool with chlorinated water for several minutes, 60% of swimmers show bronchospasm.

About 10% of chlorine used in the chlorination of water, form chlorine-containing compounds, such as chloroform, dichloroethane, carbon tetrachloride, tetrachlorethylene, trichloroethane. 70 - 90% of chlorine-containing substances formed during the water treatment is chloroform. Chloroform contributes to professional chronic poisoning with a primary lesion of the liver and central nervous system.

Also during chlorination, there is a possibility of the formation of dioxins, which are extremely toxic compounds. The high degree of toxicity of chlorinated water greatly increases the risk of developing oncology. For example, American experts consider chlorine-containing substances in drinking water indirectly or directly guilty of 20 cancer diseases per 1 million inhabitants.

Hydrogen sulphide  is found in groundwater and is predominantly inorganic in origin.

In nature, there is a constant formation of this gas during the decomposition of protein substances. It has a characteristic unpleasant smell; provokes corrosion of metal walls of tanks, boilers and pipes; is a general cellular and catalytic poison. When combined with iron forms a black precipitate of iron sulfide FeS. All of the above is the basis for the complete removal of hydrogen sulfide from drinking water (see GOST 2874-82 "Drinking Water").

It is worth noting that SanPiN 2.1.4.559-96 allows the presence of hydrogen sulfide in water to 0.003 mg / l. The question is - is this a typo in the regulatory document ?!

Microbiological indicators. Total microbial count  (TBC) is determined by the number of bacteria contained in 1 ml of water. According to the requirements of GOST, drinking water should not contain more than 100 bacteria in 1 ml.

The number of bacteria in the coliform group is of particular importance for sanitary assessment of water. The presence of Escherichia coli in water is evidence of contamination by fecal waste and, as a consequence, the risk of contaminating bacteria. Determining the presence of pathogenic bacteria in biological analysis of water is difficult, and bacteriological studies are reduced to determining the total number of bacteria in 1 ml of water growing at 37 ° C, and Escherichia coli - bacteria if. The presence of the latter signals water pollution by secretions of people, animals, etc. The minimum amount of water to be tested, ml per one E. coli, is called the collitter, and the number of E. coli per liter of water is called the index. According to GOST 2874-82, a coli index of up to 3 is allowed, a coliter is not less than 300, and the total number of bacteria in 1 ml is up to 100.

According to the norms of SanPiN 2.1.4.559-96, a total microbial number of 50 CFU / ml is permissible, common coliform bacteria  (OKB) CFU / 100ml and thermocouple coliform bacteria  (TKB) CFU / 100ml - not allowed.

Pathogenic bacteria and viruses found in water can cause diseases of dysentery, typhoid fever, paraffit, amebiasis, cholera, diarrhea, brucellosis, infectious hepatitis, tuberculosis, acute gastroenteritis, anthrax, poliomyelitis, tularemia, etc.

Company Waterman  offers you a professional solution to the task of purifying water from compounds whose content in water is higher than the normative. Our experts will advise on the issues raised and will help in the selection and implementation of an optimal water purification scheme, based on specific baseline data.