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

Dry water residue - mineral substances dissolved in water, remaining after evaporation of 1 liter. water. It is considered to be good drinking water, the dry residue of which does not exceed 1000 mg per 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 group of salts in the soil), it can be judged whether the water is contaminated by the substances found in the dry residue.

General water hardness - a value that depends on the content of alkaline earth metal salts - calcium and magnesium in the water. It is measured in conventional degrees or in milligram equivalents. One degree is the amount of salts equivalent to 10 mg of CaO in 1 liter of water. Soft water is considered to have a hardness (raw) of 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.

The biological significance of hardness salts small. Very hard water can cause a laxative effect in a person accustomed to soft water. Hard water cannot be viewed as a valuable source of calcium (100 g of cheese contains more calcium than 12 liters of water with a hardness of 24º).

The indirect effect of hard water on the functions of the body can affect the worse absorption of food cooked in hard water, vegetables and meat are poorly boiled in hard water, since proteins form insoluble complexes with hard water alkalis that prevent water from penetrating into products, which affects the quality of thermal food processing

Of great importance is the hardness of water in sanitary and technical terms. Hard water is inconvenient for washing the body, as it forms insoluble compounds with alkaline albuminates and fatty acids found on the surface of the skin, making it difficult to wash. Soap with hard water is required much more, since the formation of foam does not occur until insoluble lime and magnesia salts fall out of the water. These insoluble salts, settling on clothes, change the properties of the fabric, making it coarse and difficult to color, which makes hard water unsuitable for 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 substances, which results in the formation of carbon dioxide, which contributes to the leaching of hardness salts - calcium and magnesium from the soil. Hardness can also increase when alkaline wastewater (calcium and magnesium) enters the water.

According to SanPiN2.1.4.1074-01 "Drinking water", the dry residue of water (total mineralization) should be in the range of 1000-1500 mg / l, the total hardness is 7 mg-eq / l (maximum concentration limit is 10 mg-eq / l)

Chlorides, hygienic value:

Some indicator of water pollution water pollution organic matter animal origin are chloride salts. Human and animal excrement, especially urine, as well as kitchen slops contain a lot of sodium chloride, the combined presence of a large amount of chlorides and ammonia in the water indicates water pollution with urine.

Sulphates, hygienic value:

Exceeding the usual content of sulfuric acid salts for a given area can also serve as a sign of water pollution by animal waste, sulfur is an integral component of protein substances, during the decomposition of which and subsequent oxidation, sulfates are formed. The main significance of sulphates is that when they are high in water, they spoil its taste and can cause intestinal upset in some people (laxative effect)

An important indicator of water pollution are salts of ammonia, nitric and nitrous acids. If, in parallel with them, a large oxidizability of water is found, then it can be said with certainty that the water is contaminated with organic substances of animal origin.

Ammonia is the initial product of decay, and therefore its presence in the ode indicates fresh contamination. Salts of nitrous acid indicate the known age of contamination of the water source, since it takes some time for the first stage of ammonia mineralization to pass (turning it into nitrides).

Salts of nitric acid - nitrates are the end product of the mineralization of organic substances, and therefore their presence is an indicator of a longer period of pollution of the water source.

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

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

Norms of the nitrogenous triad in water: ammonia 2 mg / l, nitrite ion - 3 mg / ml, nitrate ion - 45 mg / l

The effect of nitrates on the body: the content of nitric acid salts in water is of independent interest. Consumption well water, rich in nitrates, causes a serious illness in infants and preschool children, expressed in pathological phenomena from the mucous membranes of the eyes, lips and skin (blue), intestines and sometimes cardiovascular systems s. The main symptom of the disease is the appearance of methemoglobin in the blood: nitrates, under the influence of microflora, turn into nitrites, which, being absorbed into the blood, lead to the formation of methemoglobin, the presence of the latter reduces, to one degree or another, the supply of oxygen to tissues.

Trace elements of water, norms and biological significance

Iron: in water it is usually found as bicarbonate of nitrous oxide. Ferrous water is harmless to the body, however, the high content of iron in the water gives it bad smell and reduces transparency due to the conversion of ferrous oxide to iron oxide hydrate under the action of atmospheric oxygen, which precipitates in the form of a brown precipitate. In economic terms, water with a high iron content is unfavorable in that it forms rusty spots on linen and harms water pipes due to the deposition of iron oxide hydrate on their walls and the massive development of ferruginous bacteria in pipes, which greatly narrows the lumen of pipes.

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

Iodine: contained in natural waters 10 mcg/l or a little more. Artesian waters are the richest in iodine and the waters of fresh open reservoirs are poor. These amounts constitute an insignificant part of the daily human need for iodine (150-200 mcg) and food products serve as its main source.

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 water. external 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, chromium and many other elements can be found in water as random impurities that enter it from tanks and vessels in which water is stored, and mainly from industrial sewage. These compounds are harmful to the body, therefore their content in water should not exceed the established maximum permissible concentrations, especially poisonous of them in drinking water 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 regions - 1.5 mg / l,IIIclimatic region - 1.2 mg / l.

Diseases and geochemical endemias, their prevention.

Mass lesions may be of a non-infectious nature, i.e., their cause may be the presence of chemical, both mineral and organic, impurities in the water.

The 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 a chemical element was also observed in food products of plant and animal origin. This in a certain way affected the health of people permanently residing in this area - they have registered diseases that were not detected in other regions. Such areas were called biogeochemical provinces, and the diseases recorded there were called geochemical endemias, or endemic diseases. There are also mercury (Gorny Altai), antimony (Fergana Valley), copper-zinc (Baimak region), copper (Urals, Altai, Donetsk region of Ukraine, Uzbekistan), silicon (Chuvashia, Danube regions of Bulgaria and Yugoslavia), chromium (Northern Kazakhstan, Azerbaijan) and other biogeochemical provinces.

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

In addition to fluorine and iodine, some other trace elements in concentrations observed in natural water 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, disorders in the development of bone tissue were found in children, in particular, delayed teething, late closure of fontanelles. Also, a decrease in the proportion of children of primary school age with harmonious morphofunctional development was noted. The pathogenesis of these disorders is associated with the well-known fact in biochemistry of the competitive relations of strontium and calcium during their distribution in the body, in particular in the skeletal system. The pathogenesis of the endemic Urov disease, which is observed in residents of Transbaikalia and other regions of Southeast Asia, is similar.

Prevention geochemical endemia mainly consists in adding trace elements missing in water. Prevention of fluorosis is provided by mechanization and automation of production; effective ventilation, respiratory protection; replacement of sources of drinking water supply or defluoridation types at waterworks.

Norms of allowance and rations in a military unit. 1Basic soldier's ration and its physiological and hygienic assessment. 2Features of catering for military personnel, basic allowances that can be in a military unit and types of rations, the chemical composition of the main soldier's ration, (number of calories, proteins, fats, carbohydrates, vitamins: A, B1, B2, PP, C, mineral salts: calcium, phosphorus, iron), 3physiological and hygienic assessment of soldiers' rations, 4the main document regulating the nutrition of military personnel, 5who draws up this document and the hygienic principles of its compilation.

1,2,3

4.5. Control over the state of storage facilities, the regime and procedure for storage, the quantitative and qualitative state of food, the legality and expediency of their spending is carried out by officials of the military unit in accordance with the requirements of the Charter of the internal service of the Armed Forces and the regulation on the military economy of the Armed Forces. The head of the medical service of the unit is obliged to control the fulfillment of sanitary requirements when receiving, storing and dispensing food, as well as the sanitary condition of the food warehouse and the quality of the food stored in it. If there are doubts about the quality of the products, he must send them for examination to a sanitary and epidemiological institution. The veterinarian of the unit (part) is obliged to: - control compliance with the veterinary and sanitary requirements for food during its intake, storage and dispensing; - exercise control over the correct placement, packing, mode of storage of food, for its timely refreshment; - 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 correct maintenance, storage and preservation of food, equipment and property. He is obliged to: - supervise the work of the food warehouse; - timely request and organize the receipt and storage of food supplies, equipment, property; - monitor the timely refreshment of food in the warehouse - ensure seasonal harvesting of potatoes and vegetables, their processing and storage, as well as the procurement of ice, hay and straw for the needs of the unit; - check at least once a month the availability and quality of food, equipment and property in the food warehouse; - ensure compliance with sanitary and hygienic requirements for food during its storage, as well as the maintenance of the food warehouse; - ensure compliance with security measures and fire prevention measures at the food warehouse. Catering in the military unit

In accordance with the Regulations on Food Supply of the Armed Forces of the Republic of Armenia in peacetime, regular canteens of military units are being created to organize meals for military personnel. Proper organization of troop nutrition is one of the essential conditions contributing to the preservation and strengthening of health, improving the combat training of personnel. Therefore, the commanders and officers of the rear must constantly take care of the nutrition of the personnel, of providing them with high-quality, full-fledged, tasty and varied food. To accomplish these tasks, it is required: - to carry out constant monitoring of the completeness of bringing the products laid down according to the norms of rations to those who eat; - correctly plan the diet of personnel, develop and observe the most appropriate diet for various contingents of military personnel, taking into account the nature and characteristics of their combat training; - to improve and equip the dining room, taking into account the requirements that ensure strict flow of movement and processing of products, the mechanization of labor-intensive work, the maintenance of all premises in exemplary condition; - properly operate technological and refrigeration equipment, tableware and kitchen utensils, timely maintain and repair them; - use products rationally, reduce waste during their processing, be sure to follow the culinary rules when cooking; - strictly comply with sanitary and hygienic requirements when processing products, preparing, distributing food, as well as observe personal hygiene (by cooks and other canteen workers); - properly organize the work of the daily work order in the canteen, ensuring the timely and high-quality performance of all work; - adhere to a strictly established serving dining tables and observance by military personnel of personal hygiene and rules of conduct in the dining room during meals; - to carry out activities aimed at improving the organization of military nutrition - competitions for the best canteen, conferences on nutrition, exhibitions of dishes; - constantly develop the subsidiary farm, taking into account the use of its products for planned and additional meals for personnel; - regularly conduct studies with the employees of the canteen, as well as test cooking, improve the classiness of the specialty of the cook staff. According to the charter of the internal service of the Armed Forces of the Russian Federation, the commander of a military unit, his deputy for logistics, and the head of the food service are required to organize good-quality and nutritious nutrition for military personnel. The latter is directly responsible for organizing good-quality and timely meals for personnel and the sanitary condition of 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 for personnel in relation to the nature of the combat training activities of the unit; - sanitary and hygienic control over the physiological usefulness of nutrition; - control over the sanitary condition of food objects; - control over compliance with sanitary and hygienic requirements during the transportation and storage of food products; - sanitary and hygienic control over the good quality of food products; - control over compliance with sanitary and hygienic requirements in the culinary processing of products, preparation and distribution of food; - medical control over dietary nutrition; - control over the health status of employees of food facilities and their compliance with the rules of personal hygiene; - organizing and conducting hygiene education and health education. The diet of military personnel provides for the number of meals during the day, the observance of physiologically correct intervals between them, the appropriate distribution of products based on rations during the day, as well as meals at a time strictly established by the daily routine. Compliance with the correct diet contributes to maintaining health, as well as increasing the body's resistance to various types of combat training load. The development of the diet of military personnel is entrusted to the commander of the military unit, his deputy for logistics, the head of the medical and head of the food services of the military unit. For personnel who eat according to the norms of 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 the Republic of Belarus, the intervals between meals should not exceed 7 hours. With this in mind, when drawing up the daily routine of the military unit, breakfast is planned to be carried out before the start of classes, lunch - after the end of the main classes, dinner - 2-3 hours before lights out. Daily allowances of rations for three meals a day are distributed according to 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 reasonable decisions on changing the diet, depending on the characteristics of combat training and the daily routine. The set of products that make up the soldier's ration allows you to cook high-quality and varied food. The combined-arms ration contains: proteins - 113 g, fats - 105 g, carbohydrates - 661 g. The calorie content of the ration is 4334 K / calories. Under normal conditions, the units adopted the following diet: hot food is taken three times a day - for breakfast, lunch and dinner, tea - 2 times (morning and evening).

The content of chloride ions in the water of natural reservoirs 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 the mineralization of water, the absolute and relative amount of C1 increases; 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 Section 2.4.2.2) and the low solubility of Ca504 and CaCO3. Therefore, with an increase in salt content in water, such widespread ions as BO and CO3 (HCO), reaching the values ​​of the solubility product in the presence of Ca2+ ions (see paragraph 2.4.4), begin to precipitate, giving way to the C1 .[ ion. ..]

The determination of chlorides serves to control the constancy of the salt background of wastewater, which changes during treatment in the organic part, and to judge the "consistency" of the analyzed samples. The content of chlorides ranges from 180 to 300 mg/l.[ ...]

Chloride content - below allowable rate, therefore, the use of wastewater in agriculture, if there are 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 destroy bad smell.[ ...]

The content of chlorides in water also determines its suitability for drinking. For drinking water, the limit value is 200 mg/l. Water with a high content is 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 plants, the maximum concentration of chlorides is 50-300 mg/l.[ ...]

Chlorides are integral part most natural waters. Like sulfates, they determine the non-carbonate hardness of water. The content of chlorides of natural origin has a wide range of fluctuations. However, in the water of rivers, the concentration of chlorides is low - it usually does not exceed 10 mg / l, therefore, an increased amount of chloride ions indicates pollution of the source by sewage. In the water of centralized water supply sources, 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 occurrence. Therefore, the detection of a large amount of chlorides is an indicator of water pollution by domestic or some industrial wastewater. In industrial wastewater, the content of chlorides depends on the nature of the production. Gradual increase in the content of chlorides in surface waters can serve as a measure of pollution of water bodies by sewage.[ ...]

Chlorides - the main ions of natural waters, have a high migration ability, which is explained by their good solubility, weakly expressed ability to sorption on suspended solids and to be consumed by aquatic organisms. Chlorides worsen the taste of water and make it unsuitable for drinking water supply, so the control of chloride content in the water of reservoirs is important for assessing water quality. For fishery water bodies, the MPC for 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, which correlate with changes in the total salinity of the water. In unpolluted river waters and waters of fresh lakes, the content of chlorides ranges from fractions of a milligram to tens and hundreds, in groundwater and sea waters it is much higher.[ ...]

If the chloride content is less than 250 mg/l, take 100 ml of filtered test water. With a higher content of chlorides take 10-50 ml. The test water is poured into two conical flasks, brought to 100 ml with distilled water, 5 drops of K2Cr04 solution are added. The solution in one flask is titrated with AgNO3, and the second flask is used as a control.[ ...]

In addition to calcium and magnesium chlorides, salts dissolved in water present in raw materials contain sodium chloride, which, as is known, does not undergo hydrolysis, but significantly increases the conductivity of the corrosive medium and thereby increases its aggressiveness. On the other hand, it contributes to the development of pitting corrosion and corrosion cracking of austenitic steels, since, like magnesium and calcium chlorides, it is a supplier of chloride ions. This, in our opinion, explains the anomalously high corrosion rates of the upper plates of the column, made of steel 12Kh18N10T in 1997, when forced plant shutdowns became more frequent, and oil with a high content of chlorides and water was supplied to the plant. As shown in the reports of the chief technologist of the plant, after only a few days of operation of the column in the conditions of the formation of an abnormally high content of HC1, the depth of damage to these elements reached 0.5 mm. Thus, the protection methods used (inhibition, neutralization, and the use of plates made of steel 12X18H10T) could not lead to the proper level of reliability of the apparatus operation. The use of a protective cap made of steel 08X17H13M2T can be considered only 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. Influence of A1SC content on the pH value and the yield of active chlorine in solutions with a chloride content of 0.427 g-ion/l: I - the yield of active chlorine. 2 - voltage, 3 - pH of the initial electrolyte, 4 - pH of the electrolyte after electrolysis.[ ...]

In drinking water, the chloride content should not exceed 30-50 mg/l, and the sulfate content should not exceed 60 mg/l. However, this is not always achievable in some southern dry regions 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 centralized water supply sources 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 sulfates 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 wide range of fluctuations: However, the concentration of chlorides in river water is low - it usually exceeds 10-30 mg / l, therefore, an increased amount of chloride ions indicates pollution of the source with sewage. In the water of centralized water supply sources, the concentration of chlorides should not exceed 350 mg / l. Limiting 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 disturbances in the gastrointestinal tract in humans. At certain ratios of sulfates and chlorides, 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 these acids are sparingly soluble at normal pH values ​​for natural waters and form colloidal solutions in water. Silicates are an undesirable impurity in the water supplying the boilers, as they form silicate scale on the walls of the boilers.[ ...]

Definition progress. Several glass beads are introduced into the flask, connected to a reflux condenser, the contents of the flask are heated to boiling and boiled for 2 hours. Upon cooling, the solution to be analyzed is transferred into a volumetric flask with a capacity of 200 ml, the walls of the flask with boron are washed with doubly distilled water. Washing water is poured into the flask and the analyzed solution is brought to the mark with the same water. Having taken an aliquot portion in 100 ml of the resulting solution, transfer it to a beaker with a capacity of 400-450 ml, dilute with distilled water to about 300 ml and neutralize with 45% sodium hydroxide solution: first, 30 ml of this solution is poured, then after stirring, add it drop by drop up to pH = 5-7. The neutralized solution is heated to a boil, 0.1 g of calcined magnesium oxide is added and on; heated for 20 minutes at a low boil. Allow the precipitate to collect at the bottom of the beaker and filter the solution through a tight filter, transferring the precipitate to the filter towards the end of the filtration. The filter cake is washed hot water until a colorless filtrate is obtained. A funnel with a 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. The filter is then treated with 3 ml of 2N. sulfuric acid, washing the walls of the glass with it first. The filter and the beaker are washed well with hot water, collecting the washings in the same flask and boiling 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. Pour then 5 ml of 2 N. acetic acid and the mixture is boiled for 5 minutes. Cool the resulting ■ 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 relative to the blank experiment solution.[ ...]

Samples for analysis for the content of organic substances were collected in hexane-washed glass bottles with a capacity of about 4 liters, equipped with Teflon stoppers. Samples for determining the content of chlorides and suspended solids were taken into 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.[ ...]

The high solubility of chlorides explains their wide distribution in all natural waters. In flowing reservoirs, the content of chlorides is usually low (20-30 mg/l). Uncontaminated groundwater in places with non-saline soil usually contains up to 30-50 mg/l of chlorine ion. In water filtered through saline soil, 1 liter can contain hundreds and even thousands of milligrams of chlorides. Water containing chlorides at 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 content of chlorides is an indicator of pollution of underground and surface water sources and sewage. The determination of chlorides is carried out according to the Mohr method.[ ...]

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

Preliminary instructions. If the content of chlorides in the taken volume of water exceeds 25 mg C1, then it is necessary to add mercury sulfate. If there are other inorganic reducing agents in the water, a correction should be made for their oxygen consumption, which is set in 20 ml of the test water by titrating it with a 0.0N permanganate solution in a slightly acidic medium in the cold (see "Determination of permanganate oxidizability").[ ...]

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

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

When analyzing celluloses containing a significant amount of chlorides, it can form in the flask white coating. In this case, the dried extract is dissolved in 15 ml of hot alcohol, 30 ml of distilled water are added and the chloride content is determined by titration with 0.1 N. AgNO3 solution, using K2SiO4 as an indicator.[ ...]

In the production of potassium nitrate, the waste is brine with a sodium chloride content of 220-250 g/l. With the commissioning of the sodium chloride recycling shop at the plant (Fig. 1.12), the content of the latter in the general flow decreased from 4800 to 1200 mg/l. At the same time, over 3,500 tons of sodium chloride are utilized annually, 40% of which is produced in the form of chemical products of reactive purity.[ ...]

Meanwhile, calculations on the change in salinity, in particular the content of chlorides and hardness salts, confirmed a decrease in scale formation by 8-9 times, i.e., approximately the same time as in bench tests.[ ...]

The effect of a low-molecular electrolyte (sodium chloride) on the £-potential was also studied in this work. With an increase in the content of sodium chloride to 1.5 g/l and the addition of a flocculant, the negative S-potential sharply decreased. With a further increase in the content of sodium chloride in wastewater, the decrease in the S-potential slowed down, the optimal dose of the flocculant increased, and the purification efficiency deteriorated. This is due to a decrease in the degree of dissociation of the ionogenic groups of the flocculant, the folding 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. During the fire processing of 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 chloride ions, and the increase in the content of chlorides in the samples corresponds to the amount of chloride ions that 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 characterizing the composition of treated wastewater are: the residue of oil or oil products in water (in mg/l), the content of suspended solids by weight, dried at a temperature of 105°C (in mg/l). amount of dissolved oxygen (in mg/l), transparency (in cm), color (in deg), color, content of chlorides and hydrogen sulfide (in mg/l), oxidizability (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 the humidity and ash content of the sediment (in %). Determination of sediment moisture should be carried out at least once a month.[ ...]

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

The main problems of coal basins are the treatment of acidic and mineralized wastewater from the Ural deposits and wastewater with a high content of chlorides and sulfates of the Moscow Region basin, the liquidation of small boiler houses and land reclamation for deposits in Eastern Siberia - purification of mine waters and household water, land reclamation, for deposits Far East - construction of treatment facilities for mine and quarry waters containing hard-to-settle dispersed suspension, increasing the efficiency of existing facilities and land reclamation.[ ...]

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

Depending on the results of the qualitative determination, 100 cm3 of the test water or its smaller volume (10-50 cm3) is taken and adjusted to 100 cm3 with distilled water. Without dilution, chlorides are determined in concentrations up to 100 mg/dm3. The pH of the titrated sample should be in the range of 6-10. If the water has a color greater than 30°, the sample is decolorized by adding aluminum hydroxide. To do this, 6 cm3 of a suspension of aluminum hydroxide is added to 200 cm3 of the sample, and the mixture is shaken until the liquid becomes colorless. The sample is then filtered through an ashless filter. The first portions of the filtrate are discarded. The measured volume of water is introduced into 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, precipitate A SL is formed, which interferes with the determination. In this case, 2-3 drops of the titrated NaCl solution are added to the titrated first sample until the orange tint disappears, then the second sample is titrated, using the first one as a control sample.[ ...]

Quality control of 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 determined. excess sodium chloride. Its main source in wastewater is the regeneration solution, which is used to wash the ion-exchange filters of the boiler house.[ ...]

The observed slight decrease in the amount of hemoglobin in the experimental animals at the 4th month of the experiment compared with the control is statistically unreliable. The content of chlorides and reserve alkalinity in the blood, as well as chlorides in the urine, did not change during all periods of the study.[ ...]

Many representatives of the most extensive genus in the family parnolistny, numbering about 100 species, are halophytes. They inhabit the salt marshes mainly of 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 the mining of copper, shale, potash, lignite, and the production of soda. Large amounts of chlorides and hardening salts end up in low to medium flow rivers, which are used for industrial purposes by many large commercial enterprises. Even after the absorption of these salts by the river (in the Elbe, for example, in the Magdeburg region, over the past 20 years, the average annual content of chlorides was 77-423 mg / l and 9.9-20.5 ° total hardness) the harmful effects still remain significant, which can be demonstrated by the following examples.[ ...]

The quantitative ionometric express method for the determination of nitrates consists in the extraction of nitrates from the material with a solution of potassium alum and the subsequent measurement of the nitrate ion in the extract with an ion-selective electrode. The method is not suitable 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 to analyze 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 dry summer of 1959 led to a significant decrease in water flow in the Ruhr. This reduced the river's ability to dilute sewage. The content of chlorides in water increased from 100 to 507 mg/l, nitrates - up to 24 mg/l, detergents - up to 1.2 mg/l. The frequency of river water reuse was 0.9, which exceeds 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 by the type and system of drilling fluid treatment. This method is not suitable for mineralized drilling fluids, i.e., fluids with a high content of chlorides and other toxic salt components. But the lack of information about neutralizing agents in the literature does not allow an objective assessment of the possibilities of the method, as well as the practical and economic feasibility its application.[ ...]

Poisonous substances of the most varied action are known, however, when they get into the water, they behave mainly as general poisons. The contamination of water with toxic substances can be indicated by some external signs and data from conventional control methods, since the presence of OM causes a change in many water parameters, such as pH, oxidizability, chlorine absorption, chloride and dissolved oxygen content, as well as data from biological and bacteriological studies. Therefore, all these indicators in conditions of possible water poisoning with OM should be determined and recorded systematically.[ ...]

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

The main type of pollution is ore and limestone dust. When water comes into contact with sludge, lime and other components are leached, 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 mg-eq/dm3, including hydration from zero to 17 mg-eq/dm3. The content of chlorides and sulfides also increases.[ ...]

Pollution of groundwater in significant volumes occurs due to the leachate - a toxic liquid released from solid waste dumps. Only within the city limits in Moscow, according to official figures, there are more than 100 landfills, and “midnight” ones have never been counted at all. The composition of the filtrate can be approximately the following and almost similar for all landfills: mineralization increased to 10-20 g / l, high contents of chlorides and sulfates, many organic acids (humic, lactic, acetic, pyruvic, etc.), the so-called " hurricane concentrations of heavy metals (including the most toxic, such as mercury), drug, sanitary, hospital, bacteriological and helminthic pollution. It is known that in the body of landfills there are active processes of fermentation and decay, i.e., decomposition of organic matter, the final product of which is water, heat, biogas (carbon dioxide and methane). There are frequent cases of spontaneous combustion of biogas with negative environmental consequences, since many landfills are saturated with synthetic plastics, the combustion of which in low-temperature conditions leads to the formation of dioxins that enter the atmosphere, the hydrosphere, and then into the trophic webs of ecosystems.[ ...]

The process is carried out in a 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 shipped to the consumer: The gas is purified from Fe203 residues, cooled and sent to an absorption column irrigated with water from 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 residual hydrogen chloride and other impurities in the scrubber, irrigated with a solution of caustic soda (NaOH), and is released into the chimney.[ ...]

Water with a dry residue of up to 1000 mg/l is called fresh, over 1000 mg/l - mineralized. Water containing an excessive amount of mineral salts is unsuitable 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 is unpleasant in taste, and its long-term use can also lead to some unfavorable physiological changes in the body (decrease in the content of chlorides in tissues, etc.). Such water, as a rule, contains little fluorine and other trace elements.[ ...]

The data concerning the redox potential of the samples were obtained only for the spring of 1976. The waters of well 12B were studied; the values ​​of 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. Well 7 water had a redox potential of +105 mV. In the stream, an increase in redox potential was observed from +90 mV (measured upstream) to +107 mV (measured downstream). With the exception of summer and autumn data from the analysis of ppb from well 6A, there is a general trend towards a decrease in the content of chlorides with increasing distance from the treatment plant. The waters of well 3 and seeps below the road are characterized by high chloride content, reflecting salt inputs from the road, as noted earlier. In all cases there was a slight increase in chloride levels in West Brook due to seeps.

Water, passing through igneous rocks, consisting of chlorine-containing minerals and salt-bearing deposits, dissolves chlorides, that is, hydrochloric acid salts, which are most often found in the form of sodium, magnesium and calcium salts. Their large number in ground and artesian waters is due not only to volcanic emissions, but also as a result of the cycle - saturation of atmospheric precipitation when passing through the soil and then exchange through the atmosphere with the ocean. An increased sodium content can be observed due to the washing out of soluble compounds with chlorine or sodium chloride from layers in contact with water. Therefore, it becomes unsuitable for economic and technical needs, or for irrigation in agriculture. Therefore, it is 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 cationic composition is represented by sodium, which forms table salt with chlorine, which provides it with a salty taste. Therefore, sodium enters tap water in the following ways: passing through rocks and dissolving carbonic, sulfate and sodium chloride salts, from industrial and household wastewater, from irrigated fields. Most often, all salt waters have the most sodium chloride relative to other salts, and therefore experts recommend installing. If magnesium chloride predominates, then it has a bitter-salty taste.

With an excessive concentration of chlorides and, accordingly, sodium, the following can be observed:

• irritation of the mucous membrane of the eyes, skin, respiratory tract;
• digestion worsens and negatively affects the secretion of the stomach;
• the body's water-salt balance is disturbed;
• diseases of the circulatory system may develop;
• there is a possibility of neoplasms of the genitourinary organs, stomach, esophagus and other digestive organs;
• cholelithiasis and urolithiasis may occur;
• the incidence of cardiovascular disease increases.

Water purification from sodium necessary because excess chloride content, which is associated with excess sodium, is harmful to household equipment:

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

Different trace elements are necessary for each cell and for the whole organism. Sodium is a microelement 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 contributes to the normal water-salt balance in cells, normalizes neuromuscular activity. It ensures the preservation of minerals in the blood in a soluble state and prevents the movement of fluid from the blood vessels into the tissues adjacent to them. It is known that the human body is not adapted to produce sodium on its own, so its supply must be replenished from various natural sources, such as water. The balanced content of sodium is provided by the kidneys. Its excess content can cause diseases such as hypertension, diabetes, neurosis. In this case, there is increased excitability, hyperactivity, impressionability, in some cases, there is excessive thirst, sweating, frequent urination.

Water purification from sodium in living conditions necessary if there is an excess of it. In drinking water, the sodium concentration 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 potassium reserves, which is necessary for the stable operation of the cardiovascular system.

There are two main methods for purifying salt water - 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 feed water, low energy and capital costs, low consumption for own needs, especially for counterflow 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, in some cases very complex additional preparation is required.

Purification using the technology has many advantages: obtaining highly purified water, low energy consumption, unlimited productivity, reliability, low operating costs and membrane regeneration costs. Disadvantages: the need for careful additional water treatment, the continuity of the equipment is required, but very significant capital costs for the equipment.

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

Reasons for changing the chemical composition of water:

1) industrial and agricultural human activity - the inflow of industrial and domestic wastewater, atmospheric precipitation containing harmful substances.

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

Indicators:

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

Dry residue

Solids content is the total content of dissolved solids in water, it gives an idea of ​​the degree of mineralization of water. The main ions that determine the dry residue are carbonates, bicarbonates, chlorides, sulfates, nitrates, sodium, potassium, calcium, and magnesium. This indicator influences other indicators of drinking water quality such as taste, hardness, corrosivity and tendency to scale.

Water with a dry residue over 1000 mg/l is called mineralized, up to 1000 mg/l - fresh. Water containing up to 50 - 100 mg / l is considered low-mineralized (distilled), 100 - 300 mg / l - satisfactorily mineralized, 300 - 500 mg / l - optimal mineralization and 500 - 1000 mg / l - highly mineralized. Mineralized water is sea, mineral, fresh - river, rain, glacier water.

Dry residue value:

1. Water with a high content of mineral salts is unsuitable 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. contributes to overheating in hot weather,
   2. leads to a violation of quenching thirst,
   3. changes water-salt metabolism by increasing the hydrophilicity of tissues,
   4. enhances motor and secretory stomach and intestines.
2. Weakly mineralized water is unpleasant in taste, its long-term use can lead to a violation of water-salt metabolism (decrease in the content of chlorides in tissues). Such water, as a rule, contains few trace elements.

Rigidity

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

Types of hardness:

1. Removable - the amount by which the total hardness of water decreases when it is boiled for 1 hour. Caused by calcium and magnesium bicarbonates, which break down and precipitate as carbonates (scale).
2. Carbonate is hardness due to bicarbonates and sparingly soluble carbonates. Removable hardness is approximately equal to carbonate hardness, but when there are a lot of sodium and calcium bicarbonates in water, carbonate hardness significantly exceeds removable hardness.
3. The constant is the hardness that remains after boiling and is due to the chlorides, carbonates, and sulfates 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 arable layer and limestone formations. Groundwater is characterized by greater rigidity than surface water. Groundwater, rich in carboxylic acids and dissolved oxygen, has a high dissolving power in relation to soils and rocks containing calcite, gypsum and dolomite minerals.

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

Hard water value:

Organoleptic properties worsen - water has an unpleasant taste;

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

In persons with sensitive skin, it contributes to the appearance of dermatitis due to the fact that calcium-magnesium soaps have an irritant effect.

In the household aspect: consumption increases detergents, scale is formed during boiling, hair becomes stiff after washing, clothing fabrics lose their softness and flexibility, the boiling of meat and vegetables worsens with a loss of vitamins as a result of binding them into indigestible 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 may serve as a defense against disease;

With a sharp transition from using hard water to soft water and vice versa, people may experience dyspeptic phenomena;

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

There is evidence that drinking soft water can cause cardiovascular disease.

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 the application of salt to roads to control snow and ice, the discharge of effluent from the chemical industry, the operation of oil wells, the discharge of sewage, irrigation drainage, pollution from the washout of solid waste and sea water intrusion into coastal areas. Each of these sources can cause pollution of surface and groundwater. The 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 the extracellular fluid; 88% of the chlorides in the body are in the extracellular space. In healthy people, almost complete absorption of chlorides occurs.

The value of chlorides:

The organoleptic properties are deteriorating - the water acquires a salty taste and, as a result, water consumption is limited;

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

They cause inhibition of gastric secretion, as a result of which the process of digestion of food is disrupted;

There is evidence that chlorides have a hypertensive effect and in people suffering from hypertension, drinking water with a high content of chlorides can cause an aggravation 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

The sulfates go to aquatic environment with wastewater from many industries. Atmospheric sulfur dioxide (SO2), produced during the combustion of fuels and released during roasting processes in metallurgy, can contribute to the sulfate content in surface waters. Sulfur trioxide (SO3), formed during the oxidation of sulfur dioxide, combines with water vapor to form sulfuric acid, which falls as "acid rain" or snow. Most sulfates are water soluble.

With aluminum sulfate, which is used as a flocculant in water treatment, an additional 20-50 mg/l of sulfates can enter the purified water. Sulfates are not removed from the water conventional methods cleaning. The concentration in most fresh waters is very low.

Sulfate value:

Sulfates are poorly absorbed from the human intestine. They slowly penetrate cell membranes and are rapidly excreted through the kidneys. Magnesium sulfate acts as a laxative in concentrations above 100 mg/l, leading to a cleansing of the gastrointestinal 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 sulfate water). Over time, a person adapts to this concentration of sulfates in the water.

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

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

They are an indicator of pollution of surface waters by industrial wastewaters and groundwaters by waters of 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 epidemically dangerous fresh water pollution by organic substances of animal origin. In some cases, the presence of ammonia does not indicate poor water quality. For example: in deep underground waters, ammonia is formed due to the reduction of nitrates in the absence of oxygen or an increased content of ammonia in swampy and peaty waters (ammonia of plant origin).

Salts of nitrous acid (nitrites) are products of incomplete oxidation of ammonia under the influence of microorganisms in the process of nitrification. The presence of nitrites indicates the possible pollution of water by organic substances, however, nitrites indicate the known age of pollution.

Salts of nitric acid (nitrates) are the end products of the mineralization of organic matter by bacteria present in the soil and in water with sufficient oxygen content. The presence of nitrates without ammonia and nitrites in the water indicates the completion of the mineralization process.

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

Nitrates and nitrites are widely distributed in environment, they are found in most foods, in the atmosphere, and in many water sources. The entry of these ions into water is facilitated by the use of fertilizers, decay of plant and animal material, domestic sewage, disposal of sewage sludge into the soil, industrial discharges, leaching from waste disposal sites and leaching from the atmosphere. In natural clear waters nitrates are usually low. However, in groundwater within settlements, livestock farms and in other places where the soil is permanently and massively polluted, the nitrate content can be high.

Because none of the commonly used water treatment and disinfection methods significantly alter nitrate levels, and because nitrate concentrations do not change appreciably in the water distribution system, levels in tap water are often completely similar to those found in 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 sections of the small intestine, concentrated mainly in saliva through the salivary glands, and excreted through the kidneys. Nitrate can easily be converted to nitrite by bacterial reduction. The reduction of nitrate to nitrite occurs throughout the body, including the stomach. This conversion depends on the pH value. In infants, in which the acidity in the stomach is normally very low, a large amount of nitrite is formed. In adults, acidity in the stomach is characterized by a pH value of 1-5, and to a lesser extent, the conversion of nitrate to nitrite occurs. 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 carcinogens.

The value of nitrates, nitrites:

They cause the development of "water-nitrate methemoglobinemia" due to the oxidation of hemoglobin to methemoglobin by nitrites. Basically, this disease occurs in children. The sensitivity of infants to the action of nitrates was attributed to their high intake in the body relative to body weight, the presence of nitrate-reducing bacteria in the upper gastrointestinal tract, and easier oxidation of fetal hemoglobin. In addition, hypersensitivity is observed in infants suffering from gastrointestinal disorders, in which the number of bacteria that can convert nitrates to nitrites increases. The use of artificial formulas for feeding children is also considered as a reason for the increase in morbidity, since the water used to prepare the formula may contain an increased amount of nitrates. In infants, a near-neutral pH in the stomach promotes bacterial growth in the stomach and upper intestines. In children, there is a deficiency in two specific enzymes that reverse the conversion of methemoglobin to hemoglobin. Boiling for a long time can exacerbate the problem due to the increase in the amount of nitrates when the water evaporates. More often, the cause of the disease was the use of private wells with microbiological contamination as a source of water (they do not contain algae that actively consume nitrates). The disease is characterized by the development of shortness of breath, 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 impairs the transport of oxygen to the tissues - this is manifested by weakness, pallor of the skin, increased fatigue.

Cause the formation of nitrosamines, some of which may be carcinogens. 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 substances.

pH value (active reaction).

Acidic are swampy waters containing humic substances, alkaline - groundwater rich in bicarbonates.

Meaning:

Defines natural properties water;

It is an indicator of pollution 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 highly dependent on pH. They form iron oxide hydrate as a metabolic end product, which gives the red color to the water. At high pH values, water acquires a bitter taste.

The efficiency of coagulation and disinfection processes depends on pH. 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, smell, turbidity, etc.), chemical (water pH pH, alkalinity, hardness, oxidizability, total mineralization (dry residue), etc.) and sanitary-bacteriological (general bacterial contamination of water, coli-index, content of toxic and radioactive components in water, etc.).

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

The normative and technical literature that makes up the 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. Hygiene requirements to the quality of water 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 non-centralized water supply. Sanitary protection of sources.

According to SanPin requirements, drinking water must be harmless in its own way. chemical composition, safe in radiation and epidemiological terms, and also have a pleasant taste and smell. Therefore, in order to save own health it is so important to know what kind of water you are drinking. To do this, it must be submitted for analysis - to check how water meets the requirements 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 can undergo significant changes (from 0.1 to 30º C). For underground sources, the water temperature is more stable (8-12 ºС).

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

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

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

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

The turbidity of water is usually expressed in milligrams per liter (mg/l); its value for drinking water according to SanPiN 2.1.4.559-96 should not exceed 1.5 mg/l. For a number of food, medical, chemical, electronic industries, 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 solids is acceptable.

Water color- an indicator characterizing the intensity of water color. It is measured in degrees on the platinum-cobalt scale, while the studied water sample is compared in color with reference solutions. The color of water is determined by the presence in it of impurities of both organic and inorganic nature. This characteristic is strongly affected by the presence in the water of organic substances washed out of the soil (humic and fulvic acids, mainly); iron and other metals; technogenic pollution from industrial wastewater. The requirement of SanPiN 2.1.4.559-96 - the color of drinking water should not exceed 20º. Separate types industries are tightening the requirements for the value of water color.

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

The smells and taste that water can have appear due to the presence of dissolved gases, organic substances, mineral salts, and chemical man-made pollution in it. The intensity of odors and tastes are determined on a five-point scale or according to the “dilution threshold” of the tested water sample with distilled water. This sets the dilution ratio necessary for the disappearance of the smell or taste. Determination of smell and taste occurs through direct tasting at room temperature, as well as at a temperature of 60º C, which causes them to intensify. Drinking water at 60º C should not have a taste and smell of more than 2 points (requirements of GOST 2874-82).

In accordance with a 5-point scale: at 0 points - smell and taste are not detected;

at 1 point, the water has a very slight smell or taste, detectable only by an experienced researcher;

with 2 points, there is a slight smell or taste, obvious to a non-specialist;

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

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

at 5 points, the water has such a strong smell or taste that it becomes completely undrinkable.

The taste of water is due to the presence of dissolved substances in it, giving it a certain taste, which can be brackish, bitter, sweetish and sour. Natural waters have, as a rule, only a brackish 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 (so-called mineral waters) tastes sour. Water with an inky or ferrous taste is saturated with iron and manganese salts; astringent taste gives it calcium sulfate, potassium permanganate; alkaline taste is caused by the content of soda, potash, alkali in water. Taste may be natural origin(presence of manganese, iron, methane, hydrogen sulfide, etc.) and artificial origin (when industrial effluents are discharged). SanPiN 2.1.4.559-9 requirements for drinking water - taste no more than 2 points.

The smells of water are given by various living and dead organisms, plant remains, specific substances released by some algae and microorganisms, as well as the presence of dissolved gases in the water, such as chlorine, ammonia, hydrogen sulfide, mercaptans, or organic and organochlorine contaminants. Smells are natural (natural) and artificial origin. The former include such odors as woody, aromatic, earthy, marsh, moldy, putrid, grassy, ​​fishy, ​​indefinite and hydrogen sulfide, etc. Smells of artificial origin get their name from the substances that define them: camphor, phenolic, chlorine, resinous, pharmaceutical, chlorine phenolic, smell of petroleum products, etc.

SanPiN 2.1.4.559-9 requirements for drinking water - smell no more than 2 points.

Chemical indicators water quality

General mineralization(dry residue). General mineralization - a quantitative indicator of substances dissolved in 1 liter of water (inorganic salts, organic substances - except for gases). This indicator is also called the total salt content. Its characteristic is the dry residue obtained by evaporating the filtered water and drying the retained residue to constant weight. Russian standards allow mineralization of water used for domestic and drinking purposes, not more than 1000 - 1500 mg/l. 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 characterized, pH is used - hydrogen and hydroxyl indicators, which determine, respectively, the acidity and alkalinity of water. The pH value is negative decimal logarithm concentration of hydrogen ions in water. With an equal amount of acidic and alkaline ions, the reaction of water is neutral, and the pH value is 7. At pH<7,0 вода имеет кислую реакцию; при рН>7.0 - alkaline. Norms SanPiN 2.1.4.559-96 require that the pH value of drinking water be in the range of 6.0 ... 9.0. Majority natural sources have a pH value within the specified limits. However, it can cause a significant change in the pH value. The correct assessment of water quality and the exact choice of the method of its purification requires knowledge of the pH of the water sources in different periods of the year. Water with low pH values ​​is highly corrosive to steel and concrete.

Water quality is often described in terms of hardness. 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 (EU Council directive). Increased hardness is the most common water quality problem.

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

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

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

General hardness - the total value of the content of calcium and magnesium salts in water; is the sum of carbonate and non-carbonate hardness.

Depending on the hardness value, water is characterized as:

The amount of water hardness varies greatly depending on what types of rocks and soils make up the catchment area; on weather conditions and the season of the year. So, in surface sources, water, as a rule, is 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 and the amount of annual precipitation. In a limestone layer, water hardness is usually 6 meq/l or more.

Drinking water hardness (according to 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 constant use of water with increased hardness is in the decrease in gastric motility, the accumulation of salts in the body, the risk of joint disease (arthritis, polyarthritis) and the formation of stones in the kidneys and bile ducts. True, very soft water is also not useful. Soft water, which has great activity, is able to wash calcium out of the bones, which leads to their fragility; development of rickets in children. Another unpleasant property of soft water is its ability to wash out beneficial organic substances, including beneficial bacteria, as it passes through the digestive tract. The best option- 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 household purposes. Consequences such as plaque on plumbing fixtures and fittings, scale formation in water heating systems and appliances are obvious! The formation of a precipitate of calcium and magnesium salts of fatty acids during domestic use of hard water leads to a significant increase in the consumption of detergents and slows down the cooking process, which is problematic for the food industry. In some cases, the use of hard water for industrial purposes (in the textile and 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 (Ca and Mg bicarbonates) on the inner walls of pipes, scale deposits in water heating and cooling systems reduce the flow area, reduce heat transfer. It is not allowed to use water with high carbonate hardness in circulating water supply systems.

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. When characterizing groundwater, in the overwhelming majority of cases, hydrocarbon alkalinity is used, that is, the content of hydrocarbonates in water. Forms of alkalinity: bicarbonate, carbonate and hydrate. Determination of alkalinity (mg-eq / l) is carried out in order to control the quality of drinking water; to determine the suitability of water for irrigation; to calculate the content of carbonates, 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 explained by the leaching of sodium chloride (common salt), a very common salt on Earth, from rocks. A significant amount of sodium chloride is found in sea water, as well as in the water of some lakes and underground sources.

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

An increased content of chlorides with the simultaneous presence of nitrites, nitrates and ammonia in the water occurs when the source is contaminated with domestic wastewater.

sulfates are present in groundwater, as a result of the dissolution of gypsum present in the layers. With an excess of sulfates in water, a person develops an upset gastrointestinal tract (these salts have a laxative effect).

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

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

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

Phosphates there is usually little in the water, so their increased content signals possible pollution by industrial effluents or effluents from agricultural fields. With an increased content of phosphates, blue-green algae develop intensively, releasing toxins into the water when they die.

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

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

Surface sources have mainly low fluorine content (0.3-0.4 mg/l). The content of fluorine in surface waters increases as a result of the discharge of industrial fluorine-containing wastewater or when water comes into contact with soils saturated with fluorine compounds. Thus, artesian and mineral waters in contact with fluorine-containing water-bearing rocks have a maximum fluorine concentration of 5–27 mg/l or more. An important characteristic for human health is the amount of fluoride in his daily diet. Usually the content of fluorine 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 fluorine enters the human body with food than with drinking water, which has an optimal content (1 mg/l).

With an increased content of fluorine in water (more than 1.5 mg / l), there is a danger of developing endemic fluorosis (the so-called "spotted tooth enamel"), rickets and anemia in the population. These diseases are accompanied by characteristic damage to the teeth, a violation of the processes of ossification of the skeleton, and exhaustion of the body. Therefore, the content of fluorine in drinking water is limited. It is also a fact that some fluorine content in water is necessary to reduce the level of diseases determined by the consequences of odontogenic infection (cardiovascular pathology, rheumatism, kidney disease, etc.). When drinking water with a fluorine content of less than 0.5 mg / l, dental caries develops, therefore, in such cases, doctors recommend using fluoride-containing 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 for fluorine - 1.5 mg/l.

Oxidability permanganate- parameter due to the presence of organic substances in water; in part, it can signal the contamination of the source with sewage. Depending on which oxidizer is used , permanganate oxidizability and bichromate oxidizability (or COD - chemical oxygen demand) differ. Permanganate oxidizability is a characteristic of the content of easily oxidizable organics, bichromate - the total content of organic substances in water. The quantitative value of these indicators and their ratio allows one to indirectly judge the nature of the organic substances present in the water, as well as the methods and efficiency of water purification.

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

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

In undissolved form (trivalent iron Fe3 +) is found in surface water sources. The water is clear - with a brownish-brown sediment or pronounced flakes;

In a colloidal state or in the form of a finely dispersed suspension. The water is cloudy, colored, yellowish-brown opalescent. Colloidal particles, being in a suspended state, do not precipitate even with prolonged settling;

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

iron bacteria that produce brown mucus water pipes Oh.

Iron content in surface waters middle lane Russia - from 0.1 to 1.0 mg / dm 3 iron; in groundwater this value reaches 15-20 mg/dm 3 and more. It is important to analyze the iron content in wastewater. Waste waters of metal-working, metallurgical, paint and varnish industries, textile, as well as agricultural effluents are especially “clogged” with iron. The concentration of iron in water is affected by the pH value and the oxygen content in the water. In well and borehole water, iron can be in oxidized and reduced form, however, when water settles, it always oxidizes 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 prolonged use of water with an excess content of iron, its compounds can be deposited in human tissues and organs. Water contaminated with iron has an unpleasant taste and brings inconvenience to everyday life. In a number of industrial plants that use water to wash 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 the product.

Manganese found in water in similar modifications. Manganese is a metal that activates a number of enzymes involved in the processes of respiration, photosynthesis, affecting hematopoiesis and mineral metabolism. With a lack of manganese in the soil, plants experience chlorosis, necrosis, and spotting. Therefore, soils poor in manganese (carbonate and over-limed) are enriched with manganese fertilizers. For animals, the lack of this element in feed leads to a slowdown in growth and development, a violation of mineral metabolism, and the development of anemia. A person suffers from both a lack and an excess of manganese.

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

An excess of manganese in water can cause a disease of the human skeletal system. This 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 ferruginous and manganese bacteria, the waste products of which in pipes and heat exchangers cause a decrease in their cross section, sometimes even complete blockage. Water used in the food, textile, plastics, etc. industries must contain a strictly limited amount of iron and manganese.

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

Sodium And potassium- the entry of these elements into groundwater occurs in the process of dissolution of bedrock. The main source of sodium in natural waters is the deposits of table salt NaCl, which arose in the places where the ancient seas were located. Potassium is less common in waters due to its uptake by soil and plants.

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

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

Potassium promotes increased 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 dysfunctions of the neuromuscular (paralysis and paresis) and cardiovascular systems and contributes to depression, incoordination of movements, muscle hypotension, convulsions, arterial hypotension, ECG changes, nephritis, enteritis, etc. Potassium MPC - 20 mg/l.

Copper, zinc, cadmium, arsenic, lead, nickel, chromium And Mercury- the entry of these elements into water supply sources occurs mainly with industrial effluents. An increase in the content of copper and zinc can also be a consequence of corrosion of galvanized and copper water pipes in the case 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 EU countries - 0.05 mg/l), arsenic - 0.05 mg/l; chromium Cr3+ - 0.5 mg/l, mercury - 0.0005 mg/l; chromium Cr4+ - 0.05 mg/l.

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

Cadmium very toxic. The 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, and hypertension. An excess of this element provokes and enhances the deficiency of Se and Zn. Symptoms of cadmium poisoning are damage to the central nervous system, protein in the urine, acute bone pain, dysfunction of the genital organs. All chemical forms of cadmium are hazardous.

Aluminum - light metal silvery white. First of all, it enters the water in the process of water treatment - in the composition 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 water, damage to the human central nervous system occurs.

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

Oxygen stays dissolved in water. 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 processes of 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 the growth of metal corrosion. An increase in water temperature, as well as its mobility, enhances the corrosion process. The increased content of aggressive carbon dioxide in water also makes the walls of concrete pipes and tanks susceptible to corrosion. The presence of oxygen is not allowed in the feed water of medium and high pressure steam boilers. hydrogen sulfide It tends to give water a characteristic unpleasant odor and cause corrosion of the metal walls of boilers, tanks and pipes. Because of this, the presence of hydrogen sulfide in drinking water and in water for most industrial needs is not allowed.

Nitrogen compounds. Nitrogen-containing substances are nitrites 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 breakdown of organic impurities, mainly urea and proteins, which enter the water with domestic wastewater. The considered group of ions is in close relationship.

The first decay product ammonia (ammonium nitrogen), is formed as a result of the breakdown of proteins and is an indicator of fresh faecal 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 nitrites is increased at the same time. Nitrates-indicator of older organic fecal water pollution. The content of nitrates together with ammonia and nitrites is unacceptable.

Thus, the presence, quantity and ratio of nitrogen-containing compounds in water makes it possible to judge how much and 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, it can be concluded that the reservoir was polluted for a long time, and during this time the water self-purified. If ammonia is present in the reservoir and there are no nitrates, then water pollution with organic substances has happened recently. Drinking water should not contain ammonia and nitrites.

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 the water exceeds the background values, then the pollution has occurred recently, and the source of pollution is close. These can be livestock farms, communal treatment facilities, clusters nitrogen fertilizers, manure, settlements, settling tanks industrial waste and etc.

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

Chlorine introduced into drinking water when it is. Chlorine exhibits a disinfecting effect by oxidizing or chlorinating (replacing) the molecules of substances that make up the cytoplasm of bacterial cells, as a result of which the bacteria die. The pathogens of dysentery, typhoid, cholera and paratyphoid are extremely sensitive to chlorine. Relatively small doses of chlorine disinfect even heavily contaminated water. However, complete sterilization of water does not occur due to the viability of individual chlorine-resistant individuals.

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

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

Chlorine is toxic and highly allergic, so chlorinated water has an adverse effect on the skin and mucous membranes. These are redness of various parts of the skin, 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 being in a pool with chlorinated water for several minutes, 60% of swimmers experience bronchospasm.

About 10% of the chlorine used in water chlorination is formed by chlorine-containing compounds, such as chloroform, dichloroethane, carbon tetrachloride, tetrachloethylene, trichloroethane. 70 - 90% of the chlorine-containing substances formed during 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. High degree The toxicity of chlorinated water greatly increases the risk of developing oncology. Thus, American experts believe that chlorine-containing substances in drinking water are indirectly or directly responsible for 20 cancers per 1 million inhabitants.

hydrogen sulfide found in groundwater and is predominantly inorganic in origin.

In nature, this gas is constantly formed during the decomposition of protein substances. It has a characteristic unpleasant odor; provokes corrosion of metal walls of tanks, boilers and pipes; is a general cellular and catalytic poison. When combined with iron, it 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 should be noted that SanPiN 2.1.4.559-96 allows the presence of hydrogen sulfide in water up to 0.003 mg/l. The question is - is this a typo in a regulatory document ?!

Microbiological indicators. Total microbial count(MCH) 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 per 1 ml.

The number of bacteria of the Escherichia coli group is of particular importance for the sanitary assessment of water. The presence of Escherichia coli in the water is evidence of its contamination with fecal effluents and, as a result, the risk of pathogenic bacteria entering it. Determining the presence of pathogenic bacteria in the 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 37ºС, and Escherichia coli - coli bacteria. The presence of the latter indicates water pollution by excretions of people, animals, etc. The minimum volume of water to be tested, ml, per one E. coli, is called colititer, and the number of E. coli in 1 liter of water is called the coli index. According to GOST 2874-82, if the index is up to 3, the colititer is at least 300, and the total number of bacteria in 1 ml is up to 100.

According to SanPiN 2.1.4.559-96, a total microbial count of 50 CFU / ml is permissible, common coliform bacteria(OKB) CFU/100ml and thermotoletic coliform bacteria(TCB) CFU/100ml - not allowed.

Pathogenic bacteria and viruses in water can cause diseases such as dysentery, typhoid fever, paraphytosis, amoebiasis, cholera, diarrhea, brucellosis, infectious hepatitis, tuberculosis, acute gastroenteritis, anthrax, poliomyelitis, tularemia, etc.

Company Waterman offers you a professional solution to the problem of water purification from compounds, the content of which in water is higher than the standard. Our specialists will advise on the issues that have arisen and help in the selection and implementation of the optimal water treatment scheme, based on specific initial data.