The hygienic value of water is determined primarily by the physiological need of a person for it.
Water, like air and food, is an element of the external environment without which life is impossible. A person can live only 5-6 days without water. This is explained by the fact that the human body is on average 65% water.
In addition, the younger the person, the higher the relative density of water in his body: a 6-week human embryo consists of 95% water, and in a new one -
HYGIENIC IMPORTANCE OF WATER
At birth, its amount is 75% of body weight. By age 50, water is 60%. The bulk of the water (70%) is concentrated inside the cell, and 30%- This is extracellular water, consisting of blood and lymph (7%) and interstitial fluid (23%). The water content in different tissues of the body is not the same: in bone tissue it makes up 20% of the mass, in muscle- 75%, in the connecting- 80%, in blood plasma- 92%, vitreous body- 99%.
In the body, only a small part of water is in a free state. The plastic function of water is due to the fact that most of it is a component of macromolecular complexes of proteins, carbohydrates and fats and forms jelly-like cellular and extracellular structures with them. In them, each colloidal particle, due to its certain size and charge, attracts water molecules to itself, causing the structuring of water, similar to a crystal lattice and reminiscent of ice. This is why many cells survive freezing without damage.
Physiological significance of water. Water plays an important role in the human body. Without water, not a single biochemical, physiological and physicochemical process of metabolism and energy occurs; digestion, respiration, anabolism (assimilation) and catabolism (dissimilation), synthesis of proteins, fats, carbohydrates from foreign proteins, fats, carbohydrates of food products are impossible. This role of water is due to the fact that it is a universal solvent in which gaseous, liquid and solid inorganic substances create molecular or ionic solutions, and organic substances are predominantly in a molecular and colloidal state. That is why it takes direct or indirect participation in almost all vital processes: absorption, transport, breakdown, oxidation, hydrolysis, synthesis, osmosis, diffusion, resorption, filtration, excretion, etc.
With the help of water, plastic substances, biologically active compounds, energy materials enter the cells of the body, and metabolic products are removed. Water helps maintain the colloidal state of living plasma. Water and mineral salts dissolved in it maintain the most important biological constant of the body- osmotic pressure of blood and tissues. The required levels of alkalinity, acidity, hydroxyl and hydrogen ions are created in the aquatic environment. Water provides the acid-base state in the body, and this affects the speed and direction of biochemical reactions. Takes part in the processes of hydrolysis of fats, carbohydrates, hydrolytic and oxidative deamination of amino acids and other reactions. Water- the main accumulator of heat, which is formed in the body in the process of exothermic biochemical metabolic reactions.
In addition, evaporating from the surface of the skin and mucous membranes of the respiratory organs, water takes part in heat transfer processes, i.e. in maintaining temperature homeostasis. During the evaporation of 1 g of moisture, the body loses 2.43 kJ (0.6 kcal) of heat.
The body's need for water is satisfied through drinking water, drinks and food, especially of plant origin. The physiological daily requirement of an adult for water (in the absence
physical activity) in regions with a temperate climate is approximately 1.5-3 l, or 90 l/month, almost 1000 l/year and 60,000-70,000 l over 60-70 years of life. This is the so-called exogenous water.
A certain amount of water is formed in the body due to metabolism. For example, with complete oxidation of 100 g of fats, 100 g of carbohydrates and 100 g of proteins, 107, 55.5 and 41 g of water are produced, respectively. This is the so-called endogenous water, produced daily in the amount of 0.3 liters.
The physiological norm of water consumption can fluctuate depending on the intensity of metabolism, the nature of food, the salt content in it, muscle work, meteorological and other conditions. It has been proven that for 1 kcal of energy expenditure the body needs 1 ml of water. That is, for a person whose daily energy consumption is 3000 kcal, the physiological need for water is 3 liters. With an increase in energy consumption during physical activity, a person’s need for water also increases. Especially if heavy physical labor is performed in conditions of elevated temperature, for example in open-hearth shops, in blast furnaces, or on a field in the heat. Then the need for drinking water can increase to 8-10 and even 12 l/day. In addition, the need for water changes under certain pathological conditions. For example, it increases with diabetes mellitus and diabetes insipidus, hyperparathyroidism, etc. In this case, the amount of water consumed by a person within a month is 30 liters, within a year - 3600 liters, over 60-70 years - 216,000 liters .
Maintaining water balance in the human body involves not only the intake and distribution of water, but also its excretion. At rest, water is excreted through the kidneys - with urine (almost 1.5 l / day), the lungs - in a vapor state (approximately 0.4 l), the intestines - with feces (up to 0.2 l). Water loss from the skin surface, which is largely associated with thermoregulation, varies, but on average amounts to 0.6 liters. Thus, an average of 2.7 liters of water are removed from the human body during resting states every day (with fluctuations from 2.5 to 3.0 liters). Under certain pathological conditions and physical activity, the release of water increases and the ratio of excretion routes given above changes. For example, with diabetes, the excretion of water through the kidneys increases - with urine, with cholera - through the digestive tract, while working in hot shops - through the skin - with sweat.
A person reacts sharply to the restriction or complete cessation of water intake into the body. Dehydration is an extremely dangerous condition in which most physiological functions of the body are disrupted. Large losses of water are accompanied by the release of significant amounts of macro- and microelements, water-soluble vitamins, which aggravates the negative consequences of dehydration for human health and life.
In case of dehydration of the body, the processes of breakdown of tissue proteins, fats and carbohydrates intensify, and the physicochemical constants of the blood and water-electrolyte metabolism change. Inhibition processes develop in the central nervous system, the activity of the endocrine and ser-
HYGIENIC IMPORTANCE OF WATER
genital-vascular systems, well-being worsens, ability to work decreases, etc. Clear clinical signs of dehydration appear if water loss amounts to 5-6% of body weight. In this case, breathing becomes more frequent, redness of the skin, dry mucous membranes, decreased blood pressure, tachycardia, muscle weakness, impaired coordination of movement, paresthesia, headache, and dizziness are observed. Water losses equal to 10% of body weight are accompanied by significant disruption of body functions: body temperature rises, facial features become sharper, vision and hearing, blood circulation deteriorate, vascular thrombosis is possible, anuria develops, mental state is disturbed, dizziness and collapse occur. Loss of water at the level of 15-20% of body weight is fatal for humans at an air temperature of 30 ° C, at a level of 25% at a temperature of 20-25 ° C.
The above convincingly demonstrates that water is one of the most valuable gifts of nature. And one cannot help but recall the expression of admiration for water by the French writer Antoine de Saint-Exupéry. The plane of the hero of his story “Planet of People” crashed during a flight over the desert, and the pilot himself experienced the death throes of dehydration and, seeing the life-giving moisture, felt incredible joy: “Water! You have no taste, no color, no smell, you It is impossible to describe. You enjoy yourself without knowing what it is. You cannot be said to be necessary for life, you are life itself. You fill us with joy that cannot be explained by our feelings. With you, the forces with which we have already said goodbye return. .. you are the greatest wealth in the world."
At the same time, if low-quality water is consumed, there is a real danger of developing infectious and non-infectious diseases. WHO statistics show that almost 3 billion of the world's population use poor-quality drinking water. Of the more than 2 thousand diseases of man-made origin, 80% arise from drinking drinking water of unsatisfactory quality. For this reason, every year 25% of the world's population is at risk of getting sick, approximately every tenth person on the planet gets sick, almost 4 million children and 18 million adults die. It is believed that out of 100 cases of cancer, from 20 to 35 (especially colon and bladder) are caused by the consumption of chlorinated drinking water. That is why the hygienic role of water and its importance for the prevention of infectious and non-infectious diseases are extremely important.
Composition of natural water. Water is one of the mysterious phenomena of nature; without it, our life is impossible. And although people have long settled near springs, used water to satisfy drinking needs, in everyday life, in industry and agriculture, they knew about its greatest value, still to this day there is still no final answer to the question: “What kind of phenomenon is water?” ?".
From the chemistry course we know that water is a simple compound that consists of two hydrogen atoms and one oxygen atom. It is designated by the formula H 2 0 and has a molecular weight of 18. The results of recent studies indicate that water has a more complex
SECTION I. HYGIENE OF WATER AND WATER SUPPLY IN PUBLIC AREAS
structure, water molecules can also be heavy if they contain isotopes of hydrogen with atomic masses 2 and 3 (deuterium and tritium) and oxygen with atomic masses 17 and 18. And although in natural water the number of heavier atoms (nuclides) varies compared to ordinary ones, it is very insignificant and the relative density of water, consisting of isotopes, is small, this ensures its extreme diversity: 42 varieties are now known. In addition, water has a complex crystalline structure, that is, it is structured. Each water molecule is generally electrically neutral, but there is a redistribution of charges in it: the side where the oxygen atom is located is more negative, and the side where the hydrogen atoms are more positive. A so-called dipole moment arises. Two neighboring molecules are attracted to each other due to electrostatic forces; a hydrogen bond occurs between them. At room temperature, each water molecule forms temporary bonds with 3-4 neighboring molecules. A kind of crystal lattice is formed in which old hydrogen bonds are constantly destroyed and new ones are formed at the same time.
From a physicochemical point of view, natural water is a complex dispersed system in which water acts as a dispersed medium, and gases, mineral and organic substances, and living organisms act as a dispersed phase. Chemical compounds in water behave differently. Some are almost insoluble, forming suspended substances, suspensions and emulsions. Others dissolve, but to varying degrees. Among mineral salts, the most soluble are chlorides, sulfates and nitrates of alkali and alkaline earth metals. Inorganic substances (salts, acids, bases) are capable of dissociating in water into metal cations (Na +, K +, Ca 2+, Mg 2+) or hydrogen (H+) and anions of acidic residues (CI, SO 2 ~ , HCO ~, CO3), or hydroxyl anions OH", forming ionic solutions. Simple organic compounds (urea, glucose and other sugars), dissolving in water, are in the form of molecular solutions. Complex organic substances (proteins, carbohydrates, fats) form colloids. Some gaseous substances are dissolved in water: oxygen (0 2), carbon dioxide (C0 2), hydrogen sulfide (H 2 S), hydrogen (H 2), nitrogen (N 2), methane (CH 4), etc.
In addition to macroelements (sodium, potassium, calcium, magnesium, nitrogen, sulfur, phosphorus, chlorine, etc.), 65 microelements 1 (iron, copper, zinc, manganese, cobalt, selenium, molybdenum, fluorine, iodine, etc.) were found in water . P.). They are contained
Microelements are chemical elements that are found in human, animal and plant tissues in concentrations of 1:100,000 (or 0.001%, or 1 mg per 100 g of weight) or less. Among microelements there are essential, i.e. vital (iron, iodine, copper, zinc, cobalt, selenium, molybdenum, fluorine, manganese, chromium, etc.), conditionally essential (arsenic, boron, bromine, lithium, nickel , silicon, vanadium, etc.) and toxic (aluminum, cadmium, lead, mercury, beryllium, barium, bismuth, thallium, etc.). Essential microelements (biomicroelements) are part of biologically active compounds: enzymes, hormones, vitamins, which play an important role in the processes of respiration, metabolism, neurohumoral regulation, immunological protection, redox homeostasis, hematopoiesis, reproduction, etc.).
HYGIENIC IMPORTANCE OF WATER
also in the tissues of animals and plants in concentrations equal to thousandths of a percent or less. The hygienic importance of microelements is determined by the biological role of many of them, since they not only take part in mineral metabolism, but also significantly influence the overall metabolism as catalysts of biochemical processes. About 20 microelements have been proven to have biological significance for animals and plants. The role of 14 of them has been studied in human physiology.
Chemicals in the water of reservoirs can be of different origins: both natural, associated with the conditions of formation of reservoirs, and man-made, due to the entry with wastewater from industrial enterprises and runoff from agricultural fields.
In addition, water contains microorganisms - bacteria, viruses, fungi, protozoa, helminths. From an ecological point of view, a distinction is made between auto- and allochthonous microflora of water bodies. The autochthonous, or aquatic, group consists of microorganisms that live and reproduce in water. Reservoirs are their natural habitat. The composition of the autochthonous microflora of unpolluted water bodies is relatively stable and characteristic of each individual water body and plays a positive role in the cycle of substances in nature, in the processes of self-purification of water bodies and maintaining biological balance. The allochthonous group consists of microorganisms that come with various pollutants (sewage, human and animal excretions). Consequently, allochthonous microflora plays a negative role. However, the danger to human health of its individual representatives is not the same. Among allochthonous microorganisms, there can be found both saprophytic, i.e., normal inhabitants of the human body, and conditionally pathogenic and even pathogenic, i.e., causative agents of infectious diseases. Allochthonous microorganisms practically do not reproduce in a reservoir and die off over time, since the conditions of the reservoir are not their natural habitat. Allochthonous microflora can persist for a long time if the substrate in which it was previously located (feces, sputum, etc.) also enters the reservoir at the same time.
In addition to the enormous physiological significance of water, it only satisfies modern requirements if its use is not accompanied by a negative, and even more harmful, effect on human health. The impact of poor quality water on public health can manifest itself in different ways: 1) in the form of infectious diseases and invasions; 2) non-infectious diseases of chemical etiology, including endemic ones; 3) unpleasant mental sensations caused by the poor organoleptic properties of water, sometimes reaching such strength that people refuse to drink it. It is in the prevention of such negative consequences for public health that the hygienic, including epidemic and endemic, significance of water lies.
Epidemic significance of water. Humanity realized the role of water in the mechanism of transmission of pathogens of intestinal infections, the development of epidemics and pandemics long before the discovery of pathogenic microorganisms. However, se-
SECTION I. HYGIENE OF WATER AND WATER SUPPLY IN PUBLIC AREAS
Today, this problem remains very relevant, despite the spread of centralized water supply to populated areas and the improvement of disinfection methods. Therefore, when addressing issues of providing the population with water, it is first of all necessary to prevent the emergence and spread of pathogens of infectious diseases that can be transmitted through water. This is achieved by constantly providing the population with good quality water in sufficient quantities. If certain hygienic requirements and sanitary rules are violated both during the organization of water supply to a populated area and during the further operation of the water supply system, an extremely dangerous, even catastrophic, situation can arise - an outbreak of a water epidemic, when an infectious disease is simultaneously transmitted to hundreds and thousands of people.
The most widespread water epidemics with severe consequences (violations of public health) are associated with the possibility of the spread of intestinal pathogens with water, which are characterized by a fecal-oral transmission mechanism. The possibility of the spread of pathogens of cholera, typhoid fever, paratyphoid A and B, salmonellosis, shigellosis, escherichiosis, leptospirosis, tularemia, and brucellosis through water has been proven. Epidemic hepatitis viruses (Botkin's disease), rotavirus gastroenteritis, adenoviruses and enteroviruses (poliomyelitis, Coxsackie and ECHO) are often found in water supplies. Here is the classification of infectious diseases proposed by WHO experts, the transmission mechanism of which involves water. /. Diseases arising from the use of contaminated water for drinking purposes.
1. Intestinal infections (leading mechanism of transmission- fecal-oral):
a) bacterial nature: cholera, typhoid fever, paratyphoid fever A and B, dysenium
teria, colienteritis, salmonellosis;
b) viral etiology: viral epidemic hepatitis A, or disease
Botkin, viral hepatitis E, polio and other enteroviral infections
infections, in particular Coxsackie and ECHO (epidemic myalgia, tonsillitis,
influenza-like and dyspeptic disorders, serous meningitis
falit), rotavirus diseases (gastroenteritis, infectious diarrhea);
c) protozoal etiology: amoebic dysentery (amebiasis), giardiasis.
2. Respiratory tract infections, the causative agents of which can sometimes cause
spread through the fecal-oral route:
a) bacterial nature (tuberculosis);
b) viral etiology (adenoviral infections, in particular rhinopharyngeal
ngitis, pharyngoconjunctival fever, conjunctivitis, rhinofarin-
gotonzillitis, rhinitis).
3. Infections of the rut and mucous membranes, which may have a fecal-oral transmission mechanism (anthrax).
4. Blood infections for which a fecal-oral transmission mechanism is possible (Q fever).
HYGIENIC IMPORTANCE OF WATER
5. Zooanthroponoses that can spread through the fecal-oral route (tularemia, leptospirosis and brucellosis).
6. Helminthiases:
a) geohelminthiases (trichocephalosis, ascariasis, hookworm);
b) biohelminthiasis (echinococcosis, hymenolepiasis).
II. Diseases of the skin and mucous membranes resulting from contact with contaminated water: trachoma, leprosy, anthrax, molluscum contagiosum, fungal diseases (athlete's foot, mycoses, etc.).
Water is one of the most important environmental factors, on which the health and sanitary living conditions of the population largely depend. Water is involved in the formation of tissues and organs of the body and is necessary for the normal course of physiological processes.
Participating in metabolism, water is continuously released from the human body through the kidneys, lungs, intestines and skin. The daily water loss of an adult is 2.5-3 liters. During heavy physical work, during the hot season or when working in hot workshops, the loss of water by the body due to increased sweating can increase to 6-10 liters.
The human body is unable to tolerate significant dehydration. The loss of 1-1.5 liters of water causes the need to restore water balance, as evidenced by a feeling of thirst. If water losses are not restored, then as a result of disruption of physiological processes, performance decreases, and at high air temperatures, thermoregulation is disrupted and overheating of the body is possible. Losing 20-25% of body weight in water can lead to death.
The body's needs for water are covered by: 1) water contained in food products and formed in tissues (1-1.5 l); 2) administered liquid - drinking water, tea, various drinks and liquid dishes, which is usually 1-1.5 liters.
Significantly large amounts of water are spent on hygiene, household and industrial needs. Water is necessary to maintain body cleanliness: for washing (5-10 l per day), hygienic shower (25-30 l). Large quantities of water are consumed in baths (120-150 liters per person washing) and laundries. Water is needed for cooking and washing dishes (5-8 liters per day per person), to maintain the cleanliness of homes and public buildings, to remove sewage through the use of sewers, and to water streets and green spaces.
Water is widely used to harden the body. Water sports in open reservoirs and swimming pools are a mass form of physical education and a valuable health-improving activity.
From the above, it is clear why the improvement of cultural and hygienic living conditions is closely related to the increase in water consumption per capita. The following minimum standards for the supply of tap water per person per day have been established: for sewered settlements - 150 liters, for partially sewered settlements - 90 liters, for unsewered settlements, including rural settlements - about 60 liters.
The quality of drinking water, which is characterized by its organoleptic properties, chemical composition and the presence or absence of pathogens, is of great hygienic importance.
The organoleptic properties of water depend on its transparency, color, taste and smell. Water with poor organoleptic properties, such as cloudy water, an unusual color, or an unpleasant taste or odor, causes disgust in people. This leads to a limitation of water consumption; the population avoids using such water even if it is not hazardous to health.
The chemical composition of water used for drinking can vary significantly. Large quantities of mineral salts can give water an unpleasant taste, negatively affect the function of the gastrointestinal tract and other organs, and interfere with the use of water in everyday life and at work.
Discharge of untreated industrial wastewater into water bodies used as water supply sources can lead to the appearance of toxic concentrations of arsenic, lead, chromium and other chemical compounds in drinking water.
The epidemiological significance of drinking water is due to the fact that it can be one of the important routes for the spread of many infectious diseases. Cholera, typhoid fever, paratyphoid A and B, bacterial and amoebic dysentery, polio, Botkin's disease, and acute enteritis are transmitted by water.
The causative agents of the listed diseases contaminate water when secretions of sick people and bacteria carriers get into it. Hospital wastewater is especially dangerous in this regard. The cause of water contamination can also be shipping with the discharge of sewage into the reservoir, pollution of the banks with sewage, mass bathing, washing clothes in the reservoir, seepage of liquid from latrine cesspools into groundwater, introduction of pathogenic microorganisms into the well by contaminated buckets. Pathogens of intestinal infections can survive in the water of open reservoirs and wells for up to several months, although in most cases their mass death occurs within 2 weeks.
In the past, when wastewater was discharged without observing sanitary rules and often into a section of the reservoir located above the intake devices of the water supply system, and the water in the latter was not systematically disinfected, outbreaks of water epidemics of cholera, typhoid and dysentery often occurred in populated areas, killing many thousands lives.
However, even today, with insufficient sanitary supervision, isolated water outbreaks of intestinal diseases occur as a result of violations in water treatment technology in water pipelines, contamination of the water supply network, as well as due to poor equipment of well shafts in rural populated areas.
Water can also cause the spread of zoonoses: leptospirosis, tularemia, brucellosis, anthrax. Leptospira enters the body of water with the urine of rodents and cattle. Diseases occur when drinking this water, as well as when coming into contact with it while working in flooded fields, swimming or washing clothes, since spirochetes enter the body through mucous membranes and minor lesions in the skin. The causative agents of tularemia enter the water during an epizootic with the secretions of sick rodents and with the corpses of rats that died from tularemia.
In addition to pathogenic microbes, Giardia cysts, roundworm and whipworm eggs, hookworm larvae, liver fluke cercariae and pathogens of other helminthic infestations can enter the human body with contaminated water.
From all of the above it follows that supplying the population with a sufficient amount of good-quality water is the most important health improvement measure and one of the main elements of improvement of populated areas.
2. HYGIENIC REQUIREMENTS FOR DRINKING WATER QUALITY AND ITS SANITARY ASSESSMENT
Water used by the population for domestic purposes must meet the following hygienic requirements:
1) have good organoleptic properties - a refreshing temperature, be transparent, colorless, without an unpleasant taste or odor;
2) be harmless in its chemical composition;
These requirements are reflected in the existing GOST in our country for the quality of drinking water supplied to the population by water pipes. Compliance of the quality of drinking water with the standards established by GOST is established by sanitary chemical and bacteriological analysis of water from the water supply network. Water must meet the following requirements.
Organoleptic properties of water. The transparency of water depends on the presence of suspended particles in it. Drinking water must be so transparent that a font of a certain size can be read through a layer 30 cm thick.
The color of drinking water obtained from surface and shallow sources may be caused by the presence of humic substances washed out of the soil. The color of drinking water is also caused by the proliferation of algae in the reservoir from which water is drawn, as well as by its contamination with wastewater. After water purification in water pipes, its color decreases. In laboratory studies, the color intensity of drinking water is compared with a conventional scale of standard solutions and the result is expressed in degrees of color. The color of the water should not exceed 20°.
The taste and smell of water are determined by the following. The presence of organic substances of plant origin in the water source gives the water an earthy, grassy, marshy smell and taste. When organic matter rots, a putrid odor occurs. The cause of the smell and taste of water may be its contamination with industrial wastewater, and in military conditions, water-based water treatment. The taste and odors of some groundwater are explained by the presence of large amounts of mineral salts and gases dissolved in them, such as chlorides and hydrogen sulfide. With conventional water treatment at waterworks, the intensity of the odor decreases, but only slightly.
During the study of drinking water, the nature of the smell or taste is determined, as well as their intensity in points: 0 - absent, 1 - very weak, 2 - weak, not yet attracting attention, 3 - noticeable, causing a disapproving assessment of the water, 4 - distinct, making unpleasant water, 5 - very strong. The permissible intensity of odor or taste is no more than 2 points.
Chemical composition of water. During the chemical analysis of drinking water supplied to the population by centralized water supply systems, indicators are determined that characterize the mineral composition of the water and have physiological significance.
The hardness of water is determined by the presence of calcium and magnesium salts in it. Water hardness is assessed in degrees or in milligram equivalents per 1 liter. Water up to 10° hardness is called soft, from 10 to 20° - medium hardness, over 20° - hard, over 40° - very hard.
As water hardness increases, the cooking of meat and legumes worsens, soap consumption increases, and scale formation in steam boilers and radiators increases, which leads to excessive fuel consumption and the need for frequent cleaning of boilers. With a sharp transition from soft to very hard water, temporary dyspeptic symptoms are possible. Water with a hardness of over 40° has an unpleasant taste.
In accordance with GOST requirements, the hardness of drinking water should be up to 20° and, in extreme cases, not exceed 40°.
Chlorides and sulfates in high concentrations give water a salty and bitter-salty taste and inhibit the secretory activity of the stomach, as a result of which it is believed that drinking water should contain no more than 350 mg/l of chlorides and 500 mg/l of sulfates.
Fluoride compounds are washed out of soil and rocks by water. Fluoride in small quantities promotes the development and mineralization of bones and teeth. All other things being equal, the incidence of dental caries in the population decreases with an increase in the concentration of fluoride in water to 1 mg/l. But water containing more than 1 -1.5 mg/l of fluoride already has an adverse effect on the body, and the teeth are primarily affected. People who drank such water in childhood have chalky or yellow or brown pigmented spots and enamel defects on their tooth enamel (Fig. 22). When the fluorine content is more than 5 mg/l, it is striking
1 g of hardness - content of 10 mg of calcium oxide in 1 liter of water; J mg-eq/l - content of 20 mg of calcium in 1 liter of water. 1 mEq/l raved 2.8° hardness.
and the osseous-ligamentous apparatus. The optimal fluorine content in drinking water is considered to be 0.7-1 mg/l, the maximum permissible concentration is 1.5 mg/l.
The presence of other toxic substances in water is mainly associated with the discharge of industrial wastewater into the reservoir. In these cases, familiarization with production technology allows you to decide what research needs to be supplemented with regular water analysis. Soviet hygienists (S.N. Cherni, a certain, etc.) developed pre-
specific permissible concentrations in water of zinc, copper, lead, arsenic and many other toxic substances, which are also specified in GOST for drinking water quality.
The amount of lead in water should not exceed 0.1 mg/l, arsenic - 0.05 mg/l. The concentration of zinc and copper should be at least 5 mg/l and 3 mg/l. Exceeding the specified concentrations of zinc and copper leads to the appearance of a specific taste in the water.
Bacteriological indicators of water quality. From an epidemiological point of view, in the hygienic assessment of water, predominantly pathogenic microorganisms are important. However, testing water for their presence is complex and time-consuming. This led to the need to use indirect bacteriological indicators. The use of these indicators is based on the observation that the less water is contaminated with saprophytes, including E. coli, the less dangerous the water is from an epidemiological perspective. Since E. coli is excreted in human feces,
6 Hygiene textbook
ka and animals, its presence signals fecal contamination of water and, therefore, the possible presence of pathogenic microorganisms in it.
When testing water for E. coli, the results of the analysis vary by the value of the coli titer or coli index. The coli titer is the smallest amount of water in which E. coli is detected. The lower the coli titre, the greater the fecal contamination of water. Coli index - the number of E. coli in 1 liter of water.
A number of experimental studies have shown that if, after water disinfection, its coli-titer rises above 300, then there is a complete guarantee regarding the death of pathogenic microbes of the typhoid-paratyphoid group, leptospira and tularemia pathogens.
Based on the presented data, GOST requirements for the quality of tap water were drawn up in relation to its bacterial composition. The number of saprophytic bacteria in 1 ml of drinking water - the microbial number - should be no more than 100. The number of E. coli in 1 liter of water should not exceed 3 or the coli-titer should be at least 300.
When assessing the quality of water from mine wells, which is not covered by the specified GOST, one must be guided by the following requirements: transparency - no less than 30 cm, color - no more than 35-40°, taste, smell - no more than 2-3 points, hardness - no more 40°, coli-titer - at least 100, microbial number - up to 400 in 1 ml.
Along with this, when assessing the quality of well water, which is usually used for drinking without any treatment, so-called chemical indicators of contamination of the water source can be used. These include organic substances and their breakdown products (ammonium salts, nitrites, nitrates). The presence of these compounds may indicate contamination of the soil through which the water flows, feeding the water source, and that along with these substances pathogenic microorganisms could have entered the water.
In some cases, each of the indicators may have a different nature, for example, organic substances may be of plant origin. Therefore, a water source can be considered polluted if: 1) there is not one, but several chemical indicators of pollution in the water, 2) bacterial indicators of pollution, for example, E. coli, are simultaneously found in the water, 3) the possibility of contamination is confirmed by sanitary inspections of the water source.
The content of organic substances in water is judged by oxidability, expressed in milligrams of oxygen,
which is spent on the oxidation of organic substances contained in 1 liter of water. Artesian waters have the lowest oxidability - up to 2<мг кислорода на 1 л; в водах шахтных «олодцев окисляемость достигает 3-4 мг кислорода на 1 л, причем она возрастает с увеличением цветности воды. Повышение окисляемости воды сверх названных, дафр указывает на.возможность загрязнения водоисточника;
The main source of ammonia nitrogen and nitrites in water is the decomposition of protein residues, animal corpses, urine and feces. With fresh pollution by waste, the content of ammonium debris in the water increases above 0.1 mg/l. Being a product of further biochemical oxidation of ammonium salts, nitrites in quantities exceeding 0.002 mg/l are also an important indicator of contamination of a water source. Nitrates are the end product of the oxidation of ammonium salts. The presence of nitrates in water in the absence of ammonia and nitrites indicates that nitrogen-containing substances, which have already managed to mineralize, entered the water relatively long ago. With an increased content of nitrates in water (more than 20 mg/l), diseases occurred in infant degei fed with nutritional mixtures prepared with this water.
Chlorides can serve as some indicator of contamination of a water source, since they are found in urine and various waste. But it must be remembered that the presence of large amounts of chlorides in water (more than 30-50 mg/l) can be caused by the leaching of chloride salts from saline soils.
When assessing well water, we are guided by the following considerations. If the sanitary conditions in which the source of water supply is located and the results of the water test are favorable, then the water can be used raw, i.e., without any treatment. If the water quality is not... meets hygienic requirements, and a sanitary examination and analysis showed that contamination of the well cannot be ruled out, then it is allowed to be used only if the water is disinfected by chlorination or boiling and its sanitary condition is improved.
waterproof rocks, water forms the first groundwater aquifer, which is called groundwater (Fig. 23). Depending on local conditions, the depth of groundwater varies from 1-2 to several tens of meters. Along the slope of the impermeable layer, groundwater moves from higher to lower places.
Filtering through the rock, the water is freed from suspended particles and microbes and enriched with mineral salts. Therefore, groundwater is transparent, has little color, and the amount of salts dissolved in it increases with depth, but in most cases is small. With fine-grained rocks, starting from a depth of 5-6 m, groundwater contains almost no microbes. If the soil is contaminated with waste and sewage, then there is a danger of bacterial contamination of groundwater. This danger is greater the more intense the pollution, the deeper it is introduced into the soil and the shallower the depth of groundwater. Studies have shown that in fine-grained rocks, bacterial contamination can spread in the direction of groundwater movement at a distance of 70-80 m. Groundwater, due to its availability, is widely used in rural areas by constructing dug - mine and drilled - tube wells. Typically, from a mine well fed by groundwater, you can get 1-10 m of water per day.
Groundwater can penetrate into an area where there is a layer of impermeable rock above it (see Fig. 23). In this area they will become interstratal, located between the waterproof bed and the waterproof roof. Depending on local geological conditions, interstratal waters can form second, third, etc. aquifers. Often, interlayer water fills the entire space between the waterproof layers and, if you cut through its roof with a well, the water in it, like in communicating vessels, rises, and in some cases even pours out in a fountain onto the surface of the earth. Interstratal water that rises in a well above the depth where it was encountered when digging it. called pressure or artesian. The depth of interstratal water varies from 15 to several hundred meters.
Interstratal waters are characterized by high transparency, colorlessness, low temperature (5-12°) and constant mineral composition. In most cases, the latter is within acceptable limits, but there are underground waters with excess salts: very hard, salty, bitter-salty, rich in fluorine, iron or hydrogen sulfide. Due to the fact that interstratal waters travel a long way underground and are covered on top with one or more waterproof layers that protect them from pollution, these waters are distinguished by bacterial purity and, as a rule, can be used for drinking raw. Constant and high flow rate, from 1 to 50 m s per hour, and good quality characterize interstratal waters as the best sources of water supply.
However, epidemic outbreaks of intestinal infections are also known when using interstratal waters. The contamination of the latter was explained by non-compliance with sanitary rules during the construction and operation of wells and the flow of water from overlying contaminated groundwater in the presence of cracks in the waterproof roof.
Groundwater can independently reach the surface of the earth and in this case is called springs. Both groundwater and interstratal water can come to the surface if the corresponding aquifer is cut by falling relief, for example mountains, deep ravines. Such springs are called descending. If a layer of pressurized interstratal water opens into a ravine or river valley, an upward, bubbling spring is formed. The quality of spring water is generally good; it depends on the aquifer feeding the spring and on the correctness of the capture system (water-capturing structures).
To prevent contamination of groundwater during operation, the following rules must be observed.
1. The place where the well is located should be located higher in the terrain and as far as possible from objects polluting the soil. This place should not become swampy or flooded. During operation, it is necessary to protect the soil surrounding the source from contamination.
2. The walls of the well or captage must be waterproof. A so-called clay castle should be installed around the top of the well walls to prevent surface water from leaking near or along the walls of the structure into the aquifer or into the well.
3. Water intake should be carried out in such a way that the well or drainage is closed and no contamination from the outside can be introduced into it.
Extensive experience suggests that groundwater is contaminated by microbes not so much during filtration through the soil, but rather when contaminants enter the well due to its poor design and water intake in individual buckets. J In rural areas, shaft wells are often installed (Fig:-24). The place for them is chosen on a hill, no closer than 20 m from possible sources of pollution (for example, a latrine) if they are located below the well, at least 80-100 m from these objects if they are located above the well. When digging a well, it is advisable to reach the second aquifer if it lies no deeper than 30 m. The side walls of the well are secured with material that ensures water resistance, i.e. concrete rings, or a wooden frame without cracks. The walls of the well must rise above the ground surface by at least 0.8 m. To construct a clay castle, dig a hole around the well - 2 m deep, 0.7-1 vt wide and fill it with well-compacted fatty clay. There is a clay castle around the ground part of the well
within a radius of 2 m, sand is added and paved with stone or brick with a slope away from the well to drain water spilled during collection.
Pumps must be recognized as the best way to raise water. Wells equipped with pumps are tightly closed and not
exposed to external pollution; The rise of water from the tinx is made easier. If water is collected using a bucket, you can also install a closed well (Fig. 25). To minimize water contamination during lifting
Rice. 25. Closed well. The bucket that rises through the gate, catching on the hook, tips over into the tray, from where it pours out through the drain pipe.
it with the help of a gate or “crane”, you should tightly close the well mouth with a lid and use only a public bucket (Fig. 26). A fence is erected within a radius of 5 m around public wells. A trough for watering animals should be placed lower down the terrain, behind a fence.
In addition to mine wells, different types of tube wells are used to extract groundwater. The advantage of tube wells is the following: they can be of any depth, their walls are waterproof, made of metal pipes, the water is raised by pumps. If groundwater is located no deeper than 6-8 m, then so-called small-tube wells are used (Fig. 27), the flow rate of which reaches 0.5-1 m 3 per hour. From the depths
From lateral aquifers, water is extracted by installing boreholes equipped with metal pipes and pumps. Deep tube wells are often used to supply water to RTS, MTF, collective farms, state farms and water supply systems in populated areas. If a spring is used for water supply, then its capture is carried out as shown in Fig. 28.
Open waters. Meteor precipitation, flowing down natural slopes of the area, forms open bodies of water: streams, rivers and lakes. Open reservoirs are partially fed by groundwater. Large artificial reservoirs and ponds are constructed through the construction of dams.
All open water bodies are subject to pollution by precipitation and melt water flowing from populated areas. Particularly heavily polluted are areas of the reservoir located near populated areas and in places where domestic and industrial wastewater is discharged. From an epidemiological point of view, the water of all open water bodies is more or less considered suspicious.
The organoleptic properties and chemical composition of water from open reservoirs depend on a number of conditions. High color water occurs in cases where rivers or their tributaries flow in swampy areas. If the river bed consists of clayey rocks, then the washed-out thin suspension causes persistent turbidity of the water. The peculiarity of reservoirs with stagnant water or with a slight current is the summer bloom, i.e., the massive development of blue-green algae. The water becomes colored and, due to the massive death and decomposition of algae, acquires an unpleasant odor and taste.
Surface waters are weakly mineralized and soft, but in stagnant lakes and reservoirs the concentration of salts can increase significantly due to water evaporation.
Open reservoirs are characterized by variable water quality - it changes depending on the season and even the weather, for example after rain.
Despite the almost continuous flow of various pollutants, most open water bodies do not experience a progressive deterioration in water quality. The reason for this is those diverse physicochemical and biological processes that lead to the self-purification of the reservoir.
Self-purification of a reservoir is as follows. First of all, the effluent is diluted and suspended particles settle to the bottom. Organic substances that get into the water are mineralized due to the vital activity of microorganisms inhabiting the reservoir, similar to what happens in the soil. For the biochemical oxidation of organic substances, the presence of dissolved oxygen in water is necessary, the reserves of which are restored as they are consumed due to diffusion from the atmosphere into water.
As a result of self-purification, contaminated water becomes clear, the unpleasant odor disappears, organic substances are mineralized, a significant number of pathogenic microbes die off and the water acquires the qualities that it had before contamination. The speed of self-purification depends on the degree of water contamination and the power of the reservoir.
But the ability of a reservoir to self-purify has limits. Severe pollution with organic substances leads to a drop in the content of dissolved oxygen, as a result of which anaerobic microflora develops in the water. As a result of putrefactive processes, the water and air above the reservoir are polluted with fetid gases, the fish die, and the reservoir becomes unsuitable for use not only as a source of water supply, but also for sports, recreational and economic purposes. The ability to self-purify is low in small and stagnant bodies of water.
From the above we can conclude that if it is necessary to use an open reservoir for water supply, preference should be given to large and flowing reservoirs. At the same time, along with protecting the reservoir from pollution by domestic and industrial wastewater, as a rule, it is necessary to reliably disinfect the water with preliminary purification to reduce suspended solids and color.
In view of all that has been said in the sanitary rules set out in the special GOST for choosing a water source, it is proposed to select water supply sources in the following order: a) interlayer pressure water; b) interstratal free-flow waters, including spring waters; c) groundwater; d) open bodies of water.
4 HYGIENIC ASSESSMENT OF METHODS FOR IMPROVING WATER QUALITY (WATER PURIFICATION)
The most commonly used methods for improving water quality include: clarification - eliminating water turbidity; decolorization - removal of water color; disinfection - freeing water from pathogenic microbes.
Lightening and discoloration of water
Clarification and partial discoloration of water can be achieved with prolonged settling. Settling is based on the fact that in slowly flowing water, suspended substances, which have a greater specific gravity than water, fall out and settle to the bottom. However, natural settling is slow, and the effectiveness of decolorization is low. Therefore, at present, for clarification and especially bleaching, pre-treatment of water with chemical reagents that accelerate the sedimentation of suspended particles (coagulation) is often used.
The process of clarification and bleaching is completed by filtering water through a layer of granular material (sand, anthracite) or fabric (field filters). To purify water, sedimentation can be used in combination with something called slow filtration.
Water is settled in sedimentation tanks, which are reservoirs several meters deep through which water continuously moves with great speed.
low speed (Fig. 29). The water remains in the sump for 4-8 hours. During this time, the largest particles settle.
Rice. 29. Scheme of a horizontal settling tank. t - feed delivery; 2 - settling tank; 3 - release of settled water; 4 - sediment.
After settling, the water is passed through a slow filter for final clarification. It is a reinforced concrete tank, at the bottom of which there is a drainage made of reinforced concrete tiles or drainage pipes with holes that drain filtered water (Fig. 30). A supporting layer of crushed stone and gravel is loaded on top of the drainage, preventing the overlying sand from spilling into the drainage holes. A filter layer of sand 1 m thick is loaded onto the gravel. The purified water is passed through the filter slowly, at a speed of 0.1-0.3 m per hour.
Slow-acting filters purify water well only after “maturation”, which consists in the fact that due to the retention of suspended impurities in the water in the upper layer of sand, the pore size decreases so much that even the smallest particles of helminth eggs and up to 99% of bacteria begin to be retained here. Every 30-60 days, 2-3 cm of the top, most contaminated layer of sand is removed with shovels.
Slow-acting filters are used on small water supply systems, for example, for water supply to villages and state farms, where reliability of operation with relatively simple operation is crucial.
Coagulation is usually used in combination with sedimentation and rapid filter
tion of water. Do I add it to water for coagulation? chemical reagents called coagulants.
The most commonly used coagulant is aluminum sulfate, which, when added to water, turns into aluminum hydroxide, which precipitates in the form of quickly settling flakes. These flakes carry with them tiny suspended matter, microbes and colloidal humic substances, which give the water color. The amount of coagulant required for water treatment is selected experimentally; it ranges from 20 to 200 mg per 1 liter of water.
The use of coagulation allows you to decolorize water, reduce the time it takes for water to settle to 2 hours, and use fast-acting filters. The speed of water filtration through sand on high-speed filters is 5-12 m per hour, i.e. 50-100 times more than on slow-acting filters; Accordingly, the area and cost of structures decreases. 10-15 minutes after the start of filtration, a filter film of coagulant flakes forms in the upper layer of sand. This improves the retention of suspended impurities and microbes. After 8-12 hours, the filter is washed for 5-10 minutes with a current of clean water directed from bottom to top. Depending on the period of operation, the filters retain from 80 to 99% of bacteria. Fast-acting filters are used in large water treatment plants. To completely eliminate the danger of water containing pathogenic bacteria, water in water pipelines is subjected to disinfection after filtration.
Water disinfection
Disinfection is one of the most widely used methods for improving water quality. It is used frequently in groundwater applications and in all surface water applications. Among the methods of decontaminating water, the most widely used are chlorination, irradiation with ultraviolet rays and boiling.
The widespread use of chlorination in water supply systems is explained by the reliability of disinfection, the availability of implementation and the low cost of this method. There are many methods of chlorination, which allows this method to be used in various situations: on water supply systems, in field camps and in military field conditions.
The principle of chlorination is based on the treatment of water with chlorine or chemical compounds containing it in an active form, which has an oxidizing and bactericidal effect.
Large water supply systems use liquid chlorine to disinfect water. It is produced in steel cylinders. Special devices are attached to the cylinders - chlorinators, which dose the flow of evaporating, gaseous chlorine into the water being disinfected.
On small water supply systems, as well as, if necessary, disinfect water in barrels or other containers instead of
chlorine use bleach (3Ca^ CaO ■ H 2 0),
which contains up to 30% active chlorine. Bleach may degrade during storage. Light, humidity and high temperature accelerate the loss of active chlorine. Therefore, bleach is stored in barrels in a dark, cool, dry, well-ventilated area, and before use, its activity is tested in a sanitary laboratory. The bleach used in practice usually contains 20-25% active chlorine.
When disinfecting water, chlorine interacts not only with microbes, but also with organic substances in the water and some salts. Therefore, when chlorinating water, it is very important to choose the correct dose of chlorine or bleach necessary for reliable disinfection. As many years of experience have shown, the dose of chlorine should be such that after disinfection, 0.2-0.5 mg/l of so-called residual chlorine remains in the water. This amount of residual chlorine, on the one hand, indicates the reliability of disinfection, and on the other, does not impair the organoleptic properties of water and is not harmful to health. Since the composition of natural waters is varied, the dose of bleach required for disinfection varies significantly. It is usually established by experimental chlorination of the water to be disinfected with different doses of bleach in several glasses. As a guide, you can use the following data.
add it in the required quantity to the water to be disinfected and mix it thoroughly. For reliable disinfection, contact of water with chlorine must last for at least 30 minutes in summer, and for at least 1 hour in winter. After disinfection, the presence of residual chlorine, smell, and taste of the water are checked and its use is allowed.
In water pipelines in which disinfected water is supplied in a continuous flow, it is also necessary to continuously add to it the appropriate amount of bleach solution. For this purpose, various dosing units are used (Fig. 31).
For reliable disinfection, it is advisable to pre-clarify and discolor turbid and colored waters.
In addition to the described conventional chlorination of water, other methods are used: rechlorination - in military conditions; chlorination with the preliminary addition of ammonia - at waterworks in cases where, with chlorination alone, the water acquires an unpleasant pharmaceutical odor, etc.
Irradiation with ultraviolet rays has a disinfecting effect in clear water within a few seconds. Turbidity, color and the presence of iron salts slow down disinfection. The advantages of this method are the simplicity of its implementation and the fact that the organoleptic properties of water do not change.
In addition, the bactericidal effect of ultraviolet rays extends to spores, viruses and helminth eggs that are resistant to chlorine.
The water supply systems of a number of cities use argon-mercury lamps designed in the USSR, which have made it possible to significantly reduce energy consumption for producing ultraviolet radiation.
In Fig. Figure 32 shows an installation for water disinfection in small water pipelines. It is a tray through which water flows at a certain speed, irradiated from above with ultraviolet rays.
Boiling is the simplest and at the same time the most reliable method of water disinfection. After boiling for 3 minutes, drinking water is completely safe even if it is heavily contaminated. The disadvantages of boiling are the impossibility of using this method for large quantities of water, the need to cool it and the rapid development of microorganisms in the event of secondary contamination of warm boiled water.
Boiling water is widely used in everyday life, in hospitals, schools, children's institutions and industries, when using water that has not undergone centralized disinfection. A variety of utensils are used for boiling water, including cubes and samovar-type batch boilers and continuous boilers with a capacity of 100 to 1000 liters per hour. The action of the latter is based on the fact that boiled water is transferred to a tank, from where it is disassembled.
It is necessary to ensure that the tank for storing boiled water has a lockable lid and a tap or fountain for dispensing water, so that the water in the tank is changed daily. Before filling the tank, the remaining water should be removed and the tank should be rinsed with boiling water.
If there is any doubt whether the water has been boiled, then carry out a test by pouring about 1 g of table salt into a test tube with water. In raw water, tiny air bubbles rise from the bottom of the test tube, but in boiled water they are absent. The test is valid only for boiled water that has stood for no more than 6-8 hours.
5. SANITARY SUPERVISION OF WATER SUPPLY IN POPULAR AREAS
There are two types of water supply: local and centralized water supply. In local water supply, water is collected by consumers directly from a source, such as a well. If there is a piped water supply, water from the source is supplied to consumers through a network of pipelines.
Medical personnel from rural medical stations and first aid stations are widely involved in sanitary supervision of local water supply.
Sanitary supervision begins with recording and certification of all sources of local water supply. To compile a sanitary passport, a sanitary-epidemiological, sanitary-topographical and sanitary-technical examination of the water supply source is carried out.
During a sanitary and epidemiological survey, it is determined whether there are diseases among the population using the source that are transmitted through water. During a sanitary survey of the area surrounding the water source, objects that pollute the soil (latrines, barnyards, etc.) are identified and Based on familiarization with the terrain and the distance between these objects and the water source, the possibility of water pollution is determined. During a sanitary inspection, the type of water source, the origin of the water, depth, flow rate, compliance with sanitary rules when constructing and equipping the water source, and the method of water intake are determined.
Having completed the local inspection, water samples are taken: for chemical analysis - in a clean, dry glass bottle, for bacteriological analysis - in sterile containers, taking all necessary precautions so as not to introduce microbes into the water from the hands or air. The bottle for chemical analysis is rinsed 2-3 times with sampled water.
From wells and open reservoirs, a water sample is taken from a depth of 0.5-1 m from the surface. To extract samples from the depths, tie a closed bottle to a pole or attach a weight to it and lower it into a reservoir on a rope. The bottle is opened at the desired depth using a string attached to the cork.
Before taking a sample, water is pumped out or drained from a pump or tap for 10 minutes, after which the tap is fired and a sample is taken.
For routine analysis, 1 liter of water is taken: 0.5 liters for chemical and 0.5 liters for bacteriological. For a complete water analysis to determine the mineral composition, 2-3 liters of water are required.
An accompanying form is attached to the water sample, which provides the following information: by whom and when (date, hour) the sample was taken, the name or location of the water source, weather conditions on the day of sampling and a few days before, brief sanitary-topographical and sanitary-technical data, location and depth of sampling, organoleptic properties of water at this moment, purpose of analysis. The sample should be delivered to the laboratory as soon as possible (in hot weather in an ice box).
Having received the results of the water analysis and comparing them with previous analyzes and data obtained during the sanitary inspection, a conclusion about the source of water supply and the necessary measures to improve it is entered into the passport. First of all, public water supply sources are certified. After certification, the materials are summarized and the project of measures to improve water supply is reported to the village council, to the collective farm board, or at a general meeting of collective farmers. During repeated inspections of the water source, data on the activities carried out is entered into the passport. Medical personnel must necessarily take part in choosing a location for newly constructed wells and in resolving issues of their design and equipment.
Wells should be cleaned and chlorinated annually in the spring. Draw water from the well, clean its walls and bottom from sediment and dirt, remove the top layer of silt and pour a layer of coarse sand or chalk onto the bottom
whom gravel. Wash the walls of the well with a 3-5% solution of bleach. After filling the well with water, add a bucket of 1% bleach solution for each cubic meter of water, mix well and leave for 10 hours, preferably overnight. Then bail out the water until the smell of chlorine disappears. After laboratory testing of the water, the well is allowed to operate.
Chlorination of wells is also carried out after repairs, when water quality deteriorates, when infectious diseases transmitted through water appear, and in other similar cases. If the groundwater stream is contaminated, it is not advisable to chlorinate the well until the cause of the contamination has been eliminated. In such cases, the population should be warned about the need to boil drinking water, and sometimes temporary chlorination of water in a public well can be arranged. To do this, add 1.5 liters of 1% bleach solution per 1 m 3 of well water. After 2 hours the well can be used. Depending on the water used, such chlorination is carried out 1-2 times a day. Disinfection of water in a well is not equivalent in effectiveness to chlorination of water in a reservoir, but still reduces the epidemiological danger of water.
When drawing water for domestic and drinking purposes from the river, it is necessary to find a non-swampy place with a convenient approach and access to it, located higher upstream than the places allocated for swimming, washing clothes, watering livestock and draining wastewater. The distance between places where the river is used for different purposes must be at least 100 m.
It is important to organize sanitary supervision of water supply in field camps. Each field camp is equipped with a water supply point, which, in addition to the water supply source, must have a container for storing water supplies. Water consumption in the field camp is about 50-70 liters per day per person.
If there is no source on the territory of the field camp, water is delivered to the water supply point in specially designated barrels or tank trucks marked “drinking water.” All types of containers must be tightly closed to protect water from contamination. For the same purpose, after filling the container with water, the lid must be tightly closed (locked in barrels) so that the container is emptied and water is drawn only through taps. Before filling, the container is emptied of any remaining water and rinsed. The container is periodically disinfected. To do this, fill it with water and for every 100 liters of water add a glass of 10% suspension of bleach in water. The water in the container is mixed and left for 2 hours. After this, the water is drained and the container is rinsed with clean water.
If the sanitary condition of the source from which the barrel is filled is suspicious, then chlorination of the water in the barrel is organized. While the water is delivered to the field camp, enough time will pass for the bactericidal effect of chlorine to manifest itself. During the hot season, when transporting or storing water, it should be protected from heating.
From the water supply point, water must be delivered in a timely manner to consumers working in various areas of the field. In the field, containers with water are stored in the shade or in specially dug holes, sheltered from the rays of the sun. Each tractor or combine must be equipped with thermoses or tanks with a supply of drinking water (5-10 l).
All persons involved in the water supply are subject to the same sanitary requirements as “the staff of food units (medical examination, testing for bacilli carriers, sanitary literacy).
Sanitary supervision of a centralized water supply system consists of monitoring the operating conditions of water supply facilities and the condition of the water supply network.
Centralized water supply has great advantages over local water supply. When installing a water supply system, it is possible to select the best water sources, protect them from pollution, equip them technically correctly, if necessary, subject the water to purification, and carry out qualified sanitary supervision. This ensures high quality tap water. But the benefits of running water don’t stop there. The supply of an unlimited amount of water directly to homes helps to increase water consumption and improve the sanitary culture of the population, helps to maintain clean homes and streets and, finally, makes it possible to install sewage systems.
In the USSR, the construction of water pipelines became an essential part of planned work on socialist reconstruction and construction of cities. Massive construction of rural water pipelines began.
In villages, workers' settlements and small towns, when installing water supply systems, underground water is usually used: artesian, groundwater and springs. The operation of such water pipelines is relatively simple."
The elements of a water supply system from underground water supply sources are: 1) a water source (bored well, catchment); *2) first lift pumping station; lifting water to the surface of the earth into a reservoir; 3) in case
the need for a water disinfection installation; 4) a second lift pumping station that supplies water to the pressure tank; .5) a network of pipelines distributing water to each "house." or “water taps” located at a distance of 100 m from each other (Fig. 33).
In those areas where good-quality groundwater is absent or insufficient, water must be taken from an open reservoir to supply the water supply system. The location for water intake is chosen above the populated area and in a place where the reservoir is least polluted. If the shore is made of filter rocks, then water is not taken
GA (\
Rice. 33. Scheme of water supply from an underground vi-:■■.,:..- source.
/ - artesian, well: 2 - first lift pumping station; 3 - reservoir; 4 - pumping station of the second lift; 5 - water tower: 6 - pipeline. supplying water to a populated area.
directly from the reservoir, but from wells dug at some distance from the shore. Significantly purified water from the reservoir, filtered through the ground, comes here.
Elements of a water supply system from an open reservoir are: 1) structures for water intake; 2) first lift pumps supplying water to water treatment facilities; 3) pumps. second rise; 4) pressure tank; 5) water supply network (Fig. 34).
The organization of a sanitary protection zone for the water supply system is of primary importance.
.; 3 o n.a sanitary protection is a territory in which a special regime is established to prevent water pollution in the water supply source and the main water supply facilities. This zone consists of two main belts.
The first zone - a strict regime zone - includes the source at the place of water intake, the territory where pumping stations, water treatment facilities, and reservoirs are located. This territory is fenced, guarded, and residence and access to unauthorized persons is prohibited. Any use of the reservoir is prohibited within the first zone zone.
The second zone - the restricted zone - with river water supply, extends mainly upstream.
along the river for tens of kilometers. Downstream the river, the restricted zone extends for several hundred meters. Within the restricted zone, the discharge of untreated wastewater is prohibited, as well as such use of the reservoir and coastal strip of land that may adversely affect the quality of water at the point of its intake by the water supply system.
With a water supply system with an underground water source, a restriction zone with a radius of 250-500 vi is arranged around a strict regime zone. Within this zone, the territory should be landscaped in an exemplary manner. Without permission from the sanitary authorities, it is prohibited to carry out excavation work that could lead to contamination of groundwater: digging wells, quarries, cesspools, installing underground irrigation, etc.
To avoid the penetration of epidemiologically hazardous contaminants into the water supply network, it is necessary that the pipelines be impenetrable and run at a sufficient distance from sewer pipes, cesspools, latrines, etc. At the intersection, water pipes should be located higher
sewer, in a casing of larger diameter pipes. It is necessary to systematically check the technical condition of inspection wells and water dispensers; if they malfunction, contaminated water may be sucked into the network.
During sanitary supervision, the quality of water in the water source, the effectiveness of its clarification and disinfection, as well as the quality of tap water in various places in a populated area are systematically monitored.
protected, under sanitary supervision and, if necessary, guarded. The simplest water supply points are set up by military units and subunits. Typically, the elements of such points are water sources equipped with water-lifting means and containers for storing and disinfecting water (Fig. 35). The responsibilities of medical workers of units and units include: 1) monitoring the provision of personnel with the appropriate amount of water; 2) carrying out sanitary reconnaissance of water sources, i.e. participation in the selection of a water source with good quality water; 3) sanitary supervision during the construction and operation of water supply points; 4) chlorination of water and provision of personnel with tablets for water disinfection; 5) sanitary and educational work among personnel on issues related to water supply.
When supplying troops with water in the field, the following minimum norms of daily water requirement per person are accepted: on vacation and in defense - 10 liters; in maneuverable combat conditions - 6 l; in maneuverable combat conditions, when obtaining good-quality water is difficult - 3 liters.
The task of sanitary reconnaissance is to select a water source with a sufficient amount of good-quality water. In field conditions, water should not contain pathogens and hazardous hazardous substances, poisons, or radioactive substances. If possible, water should have good organoleptic properties.
It is advisable to make a conclusion about the suitability of water for drinking in the field based on a local inspection of the water source and water testing. However, field conditions often force us to limit ourselves to local inspection. In addition to the above, during a local inspection in the field, by surveying the population, the possibility of intentional contamination or poisoning of water is determined. Find out whether suspicious actions of the enemy were noticed at the water source; when was the last time enemy soldiers used water; whether there are any changes in the taste or smell of the water; whether the animals used water, their condition, etc.
When examining the area surrounding the source, places where chemical or bacteriological bombs or shells exploded and areas of soil contaminated with persistent toxic or radioactive substances are identified. Pay special attention to oily films on the surface of the water and other circumstances that indicate the possibility of water poisoning.
If possible, after a local inspection, a water sample is taken and tested using field kits or sent to a laboratory for analysis.
Water from the selected source may only be used after disinfection by chlorination or boiling.
After completing the sanitary survey, security must be installed at the selected water source. At water sources, the use of which poses a health hazard, appropriate identification signs are displayed; the wells are clogged.
You can boil water in special boilers, field kitchens or kettles. Adding tea or coffee infusion improves the organoleptic properties of water, especially warm water.
Water chlorination should be carried out in tanks. Troops have various equipment for storing and transporting water, such as backpacks (Fig. 36), barrel bags (Fig. 37), stake tanks (Fig. 35), and tank trucks. To disinfect water, the usual chlorination or rechlorination described above is used,
i.e. chlorination with large doses of chlorine, which allows you to quickly and reliably disinfect even cloudy water. When overchlorinating, add 5 ml of a 1% solution of bleach to 1 liter of water (10 mg of active chlorine per 1 liter of water), mix the water and leave for 15-30 minutes. Then, to remove excess chlorine, a 0.5% solution of sodium hyposulfite (in boiled or chlorinated water) is gradually added to the water with constant stirring until it disappears.
smell and taste of chlorine. In the absence of containers, the water in the wells must be chlorinated.
If it is impossible to carry out centralized disinfection of water, the soldiers themselves disinfect the water in their flasks using Pantocide tablets. One tablet is placed in a flask with a capacity of 0.75 liters, the water is shaken periodically and consumed after 40-60 minutes.
To purify water in the field, troops have portable, transportable, and vehicle-mounted water treatment units. With the help of water treatment plants, water can be clarified, decolorized and disinfected, and, in necessary cases, freed from toxic and radioactive substances. Performance varies* | water treatment plants from 30 to 5000 liters of water per hour (Fig. 37). In addition, military units can build treatment plants from locally available materials (Fig. 38).
In the Far North it is often necessary to use freshwater ice J or snow to obtain drinking water. They are harvested in clean places. Ice and snow are melted in field kitchens or in special boilers. Since the resulting melt water contains almost no mineral salts, for long-term use it is recommended to add water to a bucket
0.3-0.5 g slaked lime and 0.1-0.2 g table salt. As a rule, melt water should be disinfected (by boiling or chlorination).
PRACTICAL WORK FOR THE CHAPTER “WATER AND WATER SUPPLY HYGIENE”
Exercise 1. Sanitary inspection of the well and sampling of water for sanitary and chemical testing.
Conduct a sanitary inspection of the well, fill out the sanitary inspection card below.
Sanitary inspection card (description) of the well
1. Region, district, locality.
2.Location of the well: in a populated area, outside the village; on the estate (whose or number), on the street (which), on the square (which), on the banks of a river, stream, on a slope, in a lowland, in a ravine, on a hill, on level ground.
3. Public or individual well; if for individual use, then ■ indicate the last name, first name and patronymic of the owner of the estate.
4. Distance to the most distant yard using the well; the number of households and residents using the well; were there any intestinal infections among the population using the well?
5. For what purposes is the well water used (household and drinking needs, livestock watering, only household needs).
6. Sanitary condition of the area surrounding the well; the distance from the well to the latrine, to the premises for livestock, to other objects polluting the soil (what); indicate whether polluting objects are located above the well or below it along the terrain.
7. Depth of the well to the bottom; depth to water surface; thickness of the water layer.
8. Sectional dimensions of the well; water supply in the well.
9. Is there enough water to meet the daily needs of the population in summer and winter; Does the well dry up in summer?
Description of the presentation by individual slides:
1 slide
Slide description:
Topic 2.2. Hygienic and environmental significance of water. Requirements for drinking water quality. Physiological role, household, sanitary and hygienic significance of water. Organoleptic properties of water. Chemical composition. Features of water epidemics.
2 slide
Slide description:
WATER: a life support factor, an indicator of the sanitary well-being of an area, population, a risk factor for changes in health status.
3 slide
Slide description:
Earth's water reserves – 1.5 billion km3 (drinking – 0.2-0.3%) VALUE: Satisfying physiological needs (~2-2.5 l/day) Residential hygiene and personal hygiene Use in industry and agriculture, food needs Transmission factor for infectious diseases of the gastrointestinal tract Recreational purposes
4 slide
Slide description:
PHYSIOLOGICAL IMPORTANCE OF WATER - biochemical reactions take place in an aquatic environment - water takes part in maintaining osmatic pressure - water is the main part of the blood and plays the role of a transport vehicle - water is the basis of acid-base balance in the body - all processes of absorption and excretion in the body take place in water environment.
5 slide
Slide description:
EXCEPTION OF WATER FROM THE BODY At rest, the following is excreted from the human body: kidneys - 1.5 l/day lungs - approximately 0.4 l intestinal tract - about 0.2 l skin pores - 0.6 l of water Daily from the human body at rest About 3 liters of water are removed. When working in hot shops, in the summer in the field, in some pathological conditions, for example, fever, the release of water can increase to 8-10 liters.
6 slide
Slide description:
Symptoms of dehydration in the human body When water in the body decreases (in% of body weight), the following is observed: 1-5% - thirst, malaise, reduced movement, loss of appetite, redness of the skin, irritability, drowsiness, increased body temperature. 6-10% - dizziness, shortness of breath, tingling sensation in the limbs, decreased blood volume, cessation of salivation, cyanosis, unclear speech, difficulty walking. 11-15% - delirium, swollen tongue, difficulty swallowing, deafness, blurred vision, lethargy and numbness of the skin, painful urination, anuria. 15-20% of body weight at air temperatures above 30 0C is fatal.
7 slide
Slide description:
Domestic water consumption standards for populated areas (per 1 resident, l/day) For agricultural areas: domestic and drinking needs with water use from standpipes - 30-50 Buildings equipped with internal water supply and sewerage without bathtubs - 125-160 The same with baths and local heaters - 160-230 The same with centralized hot water supply - 250-350
8 slide
Slide description:
Sources of water supply Diagram of groundwater occurrence: 1 - water-resistant layers; 2 - groundwater aquifer; 3 - aquifer of interstratal free-flow waters; 4 - aquifer between formation pressure waters (artesian); 5 - well fed by groundwater; 6 - well fed by interlayer free-flow water; 7 - well fed by artesian water
Slide 9
Slide description:
Sanitary assessment and hygienic requirements for drinking water quality. The triad of hygienic requirements: - favorable organoleptic properties; - water safety in terms of epidemics and radiation; - harmlessness of water in terms of chemical composition. Organoleptic properties of water. Drinking water must be of such transparency that a font of a certain size can be read through a 30 cm layer. The color of water is assessed by comparing it with a conventional scale of standard solutions, and the result is expressed in degrees. The color of the water should not exceed 20 degrees. The taste and smell of water can be caused by the presence of organic substances of plant origin, pollution by wastewater, and dissolved mineral salts.
10 slide
Slide description:
11 slide
Slide description:
The nature of taste and smell is expressed in points: 0 - absent, 1 - very weak, 2 - weak, not attracting attention, 3 - noticeable, 4 - distinct, making the water unpleasant, 5 - very strong. The permissible intensity of odor or taste is no more than 2 points.
12 slide
Slide description:
Chemical composition of water. Endemic diseases are mass diseases associated with the peculiarities of the chemical composition of water or soil in a given area. Mineral composition. The dense residue – after evaporating 1 liter of water – is no more than 1000 mg/liter. Iron - no more than 0.3 mg/l. The safe daily dose of iron is 0.8 mg/kg body weight. Iron salts give water an astringent taste. Regular consumption of drinking water with high iron content (more than 0.41 mg/kg body weight per day) - hemochromatosis (deposition of iron compounds in organs and tissues). Very high doses of iron in water can be fatal to the body (40 to 250 mg/kg). Hemorrhagic decay and detachment of sections of the gastric mucosa develops.
Slide 13
Slide description:
Calcium and magnesium - provide water hardness. There are carbonate (temporary) hardness, non-carbonate (permanent) hardness and general water hardness. Carbonate hardness (removable), determined by the presence of calcium and magnesium salts in the will, is characterized by the content of calcium bicarbonate in water, which, when water is heated or boiled, decomposes into insoluble carbonate and carbon dioxide. Non-carbonate or constant hardness - the content of non-carbonate salts of calcium and magnesium - sulfates, chlorides, nitrates. When water is heated or boiled, they remain in solution. Total hardness is defined as the total content of calcium and magnesium salts in water, expressed as the sum of carbonate and non-carbonate hardness.
14 slide
Slide description:
Assessment of water hardness: Water Hardness, mEq/L very soft water up to 1.5 mEq/L soft water from 1.5 to 4 mEq/L water of medium hardness from 4 to 8 mEq/L hard water from 8 to 12 mEq/l very hard water more than 12 mEq/l
15 slide
Slide description:
Constant consumption of water with increased hardness leads to decreased gastric motility, accumulation of salts in the body, joint disease (arthritis, polyarthritis) and the formation of stones in the kidneys and bile ducts. Calcium forms the basis of bone tissue, activates the activity of a number of important enzymes, participates in maintaining ionic balance in the body, affects processes occurring in the neuromuscular and cardiovascular systems, and affects blood clotting. Magnesium is involved in bone formation, regulation of nervous tissue, carbohydrate metabolism and energy metabolism, and improves blood supply to the heart muscle.
16 slide
Slide description:
Chlorides and sulfates give water a salty or bitter-salty taste and inhibit the secretory activity of the stomach. The norm of chlorides is 350 mg/l, sulfates – 500 mg/l. Sulfates and chlorides of calcium and magnesium form salts of non-carbonate hardness. Chlorides are present in almost all waters. MPC of chlorides in drinking water - 300 - 350 mg/l Sulfates Increased content of sulfates in water leads to gastrointestinal upset (have a laxative effect): magnesium sulfate - "Epsom salt" sodium sulfate - "Glauber's salt" MPC of sulfates in drinking water - 500 mg /l.
Slide 17
Slide description:
Fluoride compounds promote mineralization of bones and teeth. Fluoride ion content - 1 mg/l. When the content is more than 1.5 mg/l - fluorosis, less than 0.7 - dental caries. Dental damage occurs in several stages: 1. Symmetrical chalky spots on the enamel of the teeth. 2. Pigmentation (spotting of enamel). 3. Tigroid incisors (transverse striation of tooth enamel). 4. Painless tooth decay. 5. Systemic fluorosis of teeth and skeleton. Skeletal malformations in children, cretinism.
18 slide
Slide description:
Substances that have a toxic effect (carcinogenic substances, heavy metals and some trace elements - strontium, uranium, molybdenum, etc.). Molybdenum - the content in drinking water does not exceed 0.01 mg/l, in areas where ores rich in molybdenum are located - 200 mg/l. Molybdenum gives water a slightly astringent taste. In doses of 10-15 mg/l it causes an increase in the level of uric acid in the blood, osteoporosis of bones and a disease that manifests itself as pain in the hands and feet, an increase in the size of the liver (hepatomegaly), functional disorders of the digestive tract, liver and kidneys.
Slide 19
Slide description:
Strontium is a ubiquitous element; the concentration in groundwater is tens of mg/l. May enter water bodies with wastewater from enterprises. A significant portion of strontium is deposited in bone tissue. Entry into the body leads to inhibition of prothrombin synthesis in the liver, activation of osteogenesis, which reduces the incorporation of Ca into bone tissue and leads to the development of “strontium rickets.”
20 slide
Slide description:
Lead. The maximum permissible concentration of lead in tap water should not exceed 0.01 mg/l Sources of lead (Pb) in tap water: gasoline, lead contained in water pipes, welds, etc. Increased lead content in water causes acute or chronic poisoning of the body . Lead accumulates in the tissues of the body, symptoms of poisoning appear when the concentration of lead in the blood reaches 40-60 mg/100 ml - damage to the central and peripheral nervous systems, intestines, and kidneys. Lead is deposited in almost all organs and tissues of the human body, most often in hair, nails, and the mucous membrane of the gums (lead border on the gums). Lead blocks the work of enzymes that are involved in the synthesis of hemoglobin. As a result of such pathological processes, red blood cells lose their ability to carry oxygen, anemia and chronic deficiency of the body in oxygen develop. Lead blocks the formation of vitamin D.
21 slides
Slide description:
Endemic goiter is a disease associated with low intake of iodine into the body, i.e. with a decrease in its content in food products. (daily requirement 120 mg). Nitrates - increased levels cause toxic cyanosis (methemoglobinemia), especially in infants who are bottle-fed, more often in rural areas when using well water for diluting infant formula. Nitrates + amines = carcinogens. The use of chemical disinfectants for water purification and disinfection often leads to the formation of chemical by-products, and some of them (dioxins, nitrates, residual aluminum) are potentially dangerous.
22 slide
Slide description:
Epidemic and safety According to WHO, 80% of infectious diseases are associated with unsatisfactory quality of drinking water. Every year, up to 2 billion people suffer from water-related diseases. Pathogens enter water bodies with domestic and industrial wastewater, without preliminary treatment and disinfection. Groundwater becomes contaminated when sewage seeps into groundwater.
Slide 23
Slide description:
The main infectious diseases transmitted through water: intestinal infections of a bacterial nature - cholera, typhoid fever, paratyphoid A and B, dysentery, various enteritis and enterocolitis; viral diseases - infectious hepatitis A (Botkin's disease), polio, adenoviral and enteroviral infections; bacterial zoonotic infections - tularemia, brucellosis, tuberculosis, anthrax; protozoal infestations - giardiasis, dysenteric amoeba; helminthic infestations - caused by geohelminths developing without the participation of an intermediate host (ascariasis, hookworm, strongyloidiasis) and biohelminths passing through the larval stage of development in intermediate hosts - domestic animals, mollusks, crustaceans and fish (bovine tapeworm, pork tapeworm, opisthorchiasis, etc.)
24 slide
Slide description:
The main signs of water epidemics: 1) sudden one-time appearance of a large number of patients (from several tens to several thousand); 2) use of one source of water supply or bathing; 3) the predominance of adult patients at the beginning of the epidemic; 4) after the liquidation of the accident and the introduction of effective water disinfection, there was a sharp drop in the number of sick people; 5) the presence of an “epidemic tail” - diseases continue for a long time due to isolated isolated diseases, mainly among children; 6) polyetiology - the main diseases are partially mixed with other water-related diseases (typhoid fever + dysentery; cholera + dysentery; dysentery + typhoid fever + hepatitis A).
25 slide
Slide description:
The safety of water in epidemic terms is determined by indirect indicators: the total microbial number should be no more than 50 in 1 ml; Giardia cysts in 50 ml should be absent, coli-titer - the minimum amount of water that contains one E. coli - 333 ml coli-index - the number of intestinal bacteria in 1 liter - no more than 3. The residual chlorine content is at least 0.3-0.5 mg/l; during periods of epidemic danger, superchlorination is used - up to 1 mg/l.
26 slide
Slide description:
Requirements for the quality of water from centralized household drinking water supply are regulated by the state standard - sanitary rules and regulations of the Russian Federation or SanPiN of the Russian Federation SanPiN of the Russian Federation is a regulatory act that establishes criteria for the safety and harmlessness to humans of water from centralized drinking water supply systems.
All biochemical processes - assimilation, dissimilation, diffusion, osmosis, resorption occur only in the presence of water. Water releases or removes harmful and toxic substances from the body. With a lack of water, thermoregulation becomes difficult, digestion is disrupted, metabolic products accumulate and intoxication occurs.
The organ that plays a major role in maintaining fluid balance and regulating a constant level of water in the body is the kidneys. Excess water is eliminated from the body through the kidneys, which then produce more urine. The intensity of urine excretion by the kidneys is regulated, in turn, by the hormone of the posterior lobe of the pituitary gland - vasopressin. Maintaining a normal ratio of water and electrolyte concentrations is controlled by deoxycorticosterone and aldosterone from the adrenal cortex. Therefore, normally there is a dynamic equilibrium between extracellular and intracellular water.
Water enters the body through the digestive canal, from where it is carried by blood and lymph into the interstitial spaces and tissues. In humans, fluid is absorbed in the large intestine. In animals, small amounts are already in the stomach, but mainly in the small intestine.
The skin is an organ that plays a special role in water metabolism, due to its water resistance, as well as the ability to release water from the body through diffusion through the epidermis and sweating, which allows the body to reduce urination. A significant role in temperature regulation in mammals (and birds) is played by the muscles located in the skin at the base of hair and feathers and causing them to ruffle. This leads to the formation of an additional insulating layer that protects the body from heat loss. In this way, the skin protects the body from dangerous dehydration and loss of large amounts of salt. In addition, it has the ability to accumulate large amounts of water. It has been established that about 10% of the total amount of water in the body of mammals is retained by the skin, due to the content of sodium chloride in it (1/3 of the total amount of sodium chloride in the body). Thus, the skin is an important regulator of mineral metabolism in animals. Mineral metabolism in the body is impossible without the participation of water. Water plays a special role in the homeostasis of the body, mainly due to the exchange between extracellular and intracellular water. By homeostasis we mean the ability of a living organism to maintain a relatively constant state of equilibrium, for example, blood composition, electrolytes, body temperature, etc., through appropriate regulation of vital processes.
State budgetary educational institution of higher professional education
"NORTH OSSETIAN STATE MEDICAL
ACADEMY"
Ministry of Health and Social Development of the Russian Federation
HYGIENIC REQUIREMENTS AND METHODS OF HYGIENIC ASSESSMENT OF WATER SUPPLY SOURCES AND WATER QUALITY OF PHARMACY INSTITUTIONS AND PHARMACEUTICAL INDUSTRY ENTERPRISES
METHODOLOGICAL GUIDE FOR INDEPENDENT WORK ON GENERAL HYGIENE FOR STUDENTS OF THE FACULTY OF PHARMACEUTICS
Head Department of General Hygiene, Professor, Doctor of Medical Sciences Kusova A.R.
Assistant of the Department of General Hygiene Ph.D. Bitarova I.K.
Reviewers:
Head Department of Pharmacology with Clinical Pharmacology, Professor, Doctor of Medical Sciences
Bolieva L.Z.
Head Department of Humanitarian, Social and Economic Sciences, Professor Doctor of Medical Sciences
Alikova Z.R.
Approved by TsKUMS GBOU VPO SOGMA Ministry of Health and Social Development of Russia
__________2012, protocol No.
Purpose of the lesson- familiarizing students with the influence of water quality on public health, hygienic principles of rationing the quality of drinking water, and rules for choosing water supply sources.
The student must know:
Physiological and hygienic significance of water.
Water resources. Natural sources of water: underground and surface (rivers, lakes, reservoirs). Their hygienic characteristics. Pollution of water sources in conditions of rapid development of industry and chemicalization of agriculture. Sanitary protection of reservoirs
Water supply to populated areas. Centralized and decentralized water supply. Selection of water supply sources. Water consumption standards. Requirements for water quality of non-centralized water supply
Hygienic requirements for drinking water quality. Water safety indicators: organoleptic, microbiological, sanitary-chemical.
The chemical composition of water as a cause of disease.
The student must be able to:
Know the methods for determining the physical properties, chemical and microbiological composition of drinking water.
Know the device and rules of working with a pH meter, photoelectric colorimeter
Determine the organoleptic properties of water: taste, smell, transparency, color,
Determine pH, content of chlorides, sulfates, iron, total hardness, oxidability.
Give an opinion on the quality of drinking water and the conditions for using water supply sources based on the results of water analyzes and survey data of water sources.
Bolshakov A.M., Novikova I.M. General hygiene. Textbook for pharmaceutical departments, Medicine Publishing House, M., 2002.
Bolshakov A.M. Guide to laboratory exercises on general hygiene.
2nd ed., revised. and additional - M.: Medicine, 2004. - 272 p.: for students of pharmaceutical institutes and faculties.
Lakshin A.M., Kataeva V.A. General hygiene with the basics of human ecology: Textbook. – M.: Medicine, 2004 (Textbook for students of medical universities)
Pivovarov Yu.P. Guide to laboratory exercises and basics of human ecology, 2001.
Rumyantsev G.I. Hygiene XXI century, M., 2000
SanPiN 2.1.4.1074-01 “Drinking water. Hygienic requirements for water quality of centralized drinking water supply systems. Quality control"
Physiological and hygienic importance of water
Water is one of the most important environmental factors necessary for human, animal and plant life. Not a single life process in the human body can take place without water, not a single cell is able to do without an aqueous environment. It is necessary as a solvent for nutrients and as a medium in which the processes of assimilation and dissimilation, elimination and resorption, diffusion, osmosis, and filtration occur.
The physiological significance of water lies in the fact that the human body consists of 63-65% water, which represents the internal environment in which all metabolic processes take place. It makes up the main part of the body's fluids - blood, lymph, tissue fluids, secretions of the digestive and other glands, and is also an integral part of the dense tissues of the body.
A loss of 10% of water leads to severe anxiety, thirst, weakness, and tremors of the limbs, and a loss of 20-25% is incompatible with life. To maintain the physiological needs of the body, 1.5-2.0 liters of water per day is required, and this amount includes the water included in the first and third courses.
In addition, good-quality water is necessary for processing food products, manufacturing medicines, keeping pets, personal hygiene, maintaining the sanitary condition of homes, public buildings, squares, etc., for watering green spaces, performing technological processes in the production of food products, drinks, building materials, etc. It is also used for recreational, physical education and sports events, etc.
Water can fulfill its hygienic role only if it has the appropriate quality. From a hygienic point of view, under water quality understand the set of properties that determine its suitability for satisfying the physiological, hygienic and household needs of a person.