Requirements for tap water. Hygienic requirements for water
Physical (organoleptic) properties of water: transparency, color, smell, taste and temperature.
a) Transparency (the presence and content of suspended particles) is determined by two methods: by the "cross" (swimming pool, sewage treatment plants and water supply networks) and by the Snellen method (other cases).
The definition of transparency “by the cross” is made by a glass tube with a diameter of 3 cm, graduated in centimeters in height, the lower end of the tube is closed with a rubber stopper fitted with a drain hole with a clip. At the bottom of the pipe, on the cork, is placed a white porcelain disk with black lines forming a cross and with four black dots, one in the middle of each part of the cross. The length of the pipe is 350 cm. Transparency is expressed in centimeters of the height of the water column.
According to Snellen: water is shaken and placed in a cylinder with a transparent bottom and a tube to release water. The cylinder is placed at 4 cm from the Snellen font number 1 and released carefully to a clearly distinguishable font. Natural pool: a white disk d = 20 cm is seen at a depth of 4 m. An artificial pool - at any depth a white disk d = 15 cm on a black background.
b) Color (chromaticity) - should be colorless (there may be iron salts, clay particles, algal blooms). The chromaticity is normalized in degrees on a platinum (or chromium) cobalt scale and should not be more than 20 ° (colorless, dark yellow, brown, etc.).
c) Smell - no. Smells of water are determined by their nature and intensity. 0 is absent; 1 - very weak; 2 - weak; 3 - noticeable; 4 - distinct; 5 - very strong. Smells of water of natural origin: aromatic (cucumber, floral), marsh (muddy, waste), hydrogen sulfide (rotten eggs), etc.
Odors of artificial origin are designated by name by the relevant substances: chlorine, gasoline, phenolic (industrial wastewater), etc.
The smell of water is measured by its intensity in points at a temperature of 20 ° (the nature of the smell).
The smell of drinking water should not be more than 2 points.
d) Taste: - pleasant. There are 4 types of taste: salty, bitter, sweet, sour. Other types of taste sensations are called flavors:
May be from mineral salts (ferrous chloride salts, sulfates);
Industrial chemical waste;
Plant origin (water bloom).
The intensity in points should be no more than 2 points.
e) Temperature - 7-12 ° is considered the most favorable. At a higher temperature, water does not have a refreshing effect, and at temperatures below 5 ° C, colds can occur, especially if water is drunk in a heated state, for example, after training sessions.
The chemical composition of water must differ by the known constancy:
a) the dry residue. The amount of mineral salts in 1l of filtered water after evaporation usually does not exceed 500-600 mg, for drinking water it should not exceed 1000 mg / l.
b) Organic matter: animal and vegetable origin. The amount of organic matter in water is judged indirectly by the amount of oxygen consumed for their oxidation. Groundwater - does not exceed 2-4 mg of oxygen per 1 l; river - no more than 7 mg / l.
c) Nitrogen compounds: ammonium salts, nitrogen and nitrogen salts, their total amount should not exceed 45 mg / l. The initial product of decay of organic animal products in water is ammonium salts. They indicate fresh water pollution. The presence of nitrous and, in particular, nitric acid in water is evidence of a known age of pollution.
d) Chlorides. Their content in drinking water should not exceed 20-30 mg per
liter. Valid for some mineralized sources is 350 mg / l. Excessive inhibition of gastric secretion; reduces diuresis; increases blood pressure.
d) Sulfates. Their content should be no more than 500 mg / l. When their excess deteriorates the taste of water, possible violations of water-salt balance and dyspeptic phenomena.
e) Iron salts. Harmless, but spoil the taste, give a yellow color, falls in the form of a brown precipitate of iron oxide hydrate. Normally, it should not exceed 0.3 mg / l, but it can be up to 1 mg / l.
g) Calcium and magnesium salts. The hardness of the water depends on their content, it is not very hard to wash. Water hardness should not exceed 7 mg / eq per 1 l; up to 3.5 mg / eq - mild (10 °). It is also measured in degrees: 1 mg / eq.
equals 2.8 ° stiffness. With a high content may occur urolithiasis.
h) Fluorine affects the condition of the teeth. If there is a lot of it, then a disease called fluorosis occurs, in which dark spots appear on the tooth enamel, which then lead to tooth decay. With insufficient fluorine content, "caries" develops. Optimally 0.7-1.0 mg / l (the norm is up to 1.5 mg / l).
i) Iodine - in people with a low content of iodine in water, there is hypertrophy of the thyroid gland - goiter.
Biological components of water. Water contains a large number of bacteria and helminths, algae and fungi, single and multicellular microorganisms. Through water contaminated with pathogens can be transmitted:
a) intestinal infections: typhoid fever, dysentery, cholera.
b) viral diseases: hepatitis, poliomyelitis;
g) fungal: athlete.
For the sanitary-epidemiological assessment of water, the titer of microbial colonies (microbial amount of water) is primarily determined. At a rate of no more than 100 colonies of microbes in 1 ml of tap water, up to 1000 permissible in well water.
Water is one of the important factors affecting the health and productivity of animals. Animals receive the bulk of the water from drinking and feeding, and only a small amount of it is formed in the body due to the oxidation of fats, carbohydrates and proteins.
The lack of water slows down the processes of digestion and absorption, delays the excretion of metabolic products from the body and complicates thermoregulation. Loss by the body of 10% of water causes a weakening of the heart, muscle tremors, a decrease in appetite and an increase in body temperature. The loss of an animal organism of 20% of water and more, as a rule, leads to death. Under short periods, milk yield decreases by 8–40%. Insufficient water consumption by fattened young animals reduces weight gains by 12–20% (II Yarov). Timely and sufficient water consumption by animals is one of the important conditions for their high productivity.
Of great importance is the quality of water used for drinking purposes. In recent years, cases of poisoning of animals with water have become more frequent, because, for one reason or another, industrial drains are often discharged into water bodies. Sanitary and hygienic water quality is determined by a complex of organoleptic, physico-chemical, bacteriological and biological indicators. Important indicators of water quality are its physical properties: temperature, transparency, color, smell, taste and taste.
When cold water is consumed in winter, animals may decrease their productivity and increase feed costs for products, since energy is consumed to warm the water in the body. It has been established that for warming a cow in the body of 30-40 liters of water consumed from 2 to 37 ° C consumes as much thermal energy as is required to form 1-1.3 kg of milk. Pregnant uterus is given water with a temperature of 12–15 ° C, and for young stock it is heated to 30 ° C, depending on age. The hotels should be watered with water at a temperature of 25 ° C (II Yarov).
Drinking water must meet certain chemical requirements. To determine the quality of water and its suitability for watering animals, the content of such chemicals is determined, which serve as indicators of contamination with various wastes and wastewater. Good water should have a neutral or slightly alkaline reaction (pH 6.5-8.0). When polluted by wastewater from industrial enterprises, it usually has an acidic reaction. Alkaline reaction has water contaminated with organic waste of animal origin.
The amount of mineral and organic substances dissolved in water is judged by the dry residue, which is obtained by evaporating I l of filtered water. With a dry residue of more than 1000 mg / l, water is not suitable for consumption.
The quality of water depends on its hardness, which is characterized by the amount of calcium and magnesium salts dissolved in water.
Water can contain various organic substances, the amount of which is judged by the oxidizability of water (based on oxygen consumed for the oxidation of organic substances). The more organic substances in water, the more oxygen is spent on their oxidation. The oxidizability of good water should not exceed 2-5 mg 02 / l. High oxidizability often indicates contamination of water and the danger of its sanitary. The presence of organic matter in water is indirectly judged by the content of dissolved oxygen, which is constantly consumed in the water of open reservoirs for their oxidation. Therefore, highly polluted water may not contain dissolved oxygen at all.
When assessing the quality of water determine the content of ammonia, nitrite and nitrates. The presence of albuminoid ammonia and nitrite in the water indicates that it is polluted with animal waste (manure, urine, etc.). Such water is dangerous in the sanitary relationship. Ammonia and nitrites have a toxic effect on animals. Under their influence resistance of an organism decreases, and also cases of a poisoning are possible. In benign water, ammonia and nitrite should be absent, and nitrate should not be more than 40 mg / l.
The water contaminated with manure, urine and wastewater, there is a high chloride content. They can also be found in water passing through saline soils. A high amount of chlorides with the simultaneous content of ammonia, nitrite and increased oxidability in water indicates its pollution and the poor quality of water. Such water should not be used for watering animals. There is evidence that when watering cows with water containing 500 mg / l and more of chlorides of mineral origin, the functions of the digestive organs are suppressed and the milk yield decreases. Sulphates have the same hygienic value as chlorides. They can appear in water as a result of oxidation of decomposed protein substances or when gypsum is contained in it.
Water can be a source of causative agents of some infectious and invasive diseases. Through it, foot and mouth disease, erysipelas, paratyphoid fever, leptospirosis, brucellosis, tuberculosis, plague, anthrax, etc. can spread.
To provide livestock farms with water they use atmospheric, underground and surface water sources.
The artesian waters meet the highest sanitary requirements (these are waters lying between two waterproof layers). They are free from pollution and microorganisms, rich in mineral salts. However, they often have an excess of mineral salts, which give the water a bitter-salty taste. Animals drink this water reluctantly. With prolonged use of water with a high salt content, gastrointestinal diseases can be observed.
Pollution of natural water. All pollutants, including those of anthropogenic, man-made origin, entering natural waters, cause various qualitative changes in them:
change in the physical properties of water;
changes in the chemical composition of water, in particular the appearance of harmful substances in it;
substances floating on the surface of the water and deposits on the bottom;
a reduction in the amount of dissolved oxygen in water due to its consumption for the oxidation of organic pollutants entering the water;
the emergence of new bacteria and other microorganisms, including pathogens.
Pollution of natural waters adversely affects fish, waterfowl, animals and other organisms that get sick and die in significant quantities.
Oil and its derivatives have a harmful effect on surface and groundwater. They not only form on the surface of the film, but also deposits on the bottom. Even a small content of oil (0.2-0.4 mg / l) is accompanied by the appearance of a specific odor, which does not disappear after chlorination and filtration of water. The presence of petroleum products has a particularly negative effect on fish, causing massive illness and death. The oil content in water above 0.1 mg / l gives the fish meat an unremovable taste and peculiar smell under any technological treatments.
Phenolic compounds contained in the wastewater of various enterprises are of great danger. Possessing strong antiseptic properties, phenols violate biological processes in water, giving it a sharp, unpleasant smell and worsening the conditions of reproduction of fish.
In recent years, the pollution of water by synthetic surface-active substances (SAL), which are contained in the wastewater of some industries, has been observed. The effect of synthetic surfactants is manifested in the increase in water tastes and odors, the formation of persistent accumulations of foam and the deterioration of biochemical parameters. Already at low concentrations of synthetic surfactants in water, the growth of algae and other vegetation stops.
The release of warm water from various power plants causes an intensification of evaporation and is accompanied by an increase in mineralization. At the same time there is an accumulation of organic matter, followed by its decomposition. The consequence of these processes is the reduction of dissolved oxygen in water, which adversely affects plant and animal organisms.
The greatest danger to natural waters, the health of people, animals and fish are various radioactive waste. In fish, animals and plants, biological processes of radioactive substances take place. Small organisms containing these substances in small doses are absorbed by larger ones, in which dangerous concentrations are already generated. That is why individual freshwater fish are several thousand times more radioactive than the aquatic environment in which they inhabit.
Greater danger is the contamination of water with mercury. Of the 9,000 tons of mercury produced annually in the world, 5,000 tons later end up in the ocean.
Self-purification of water. In the process of self-purification, dying off of saprophytes and pathogenic microorganisms occurs. They die as a result of: depletion of water with nutrients; bactericidal action of ultraviolet rays of the sun, which penetrate into the water column by more than 1 m; the effects of bacteriophages and antibiotic substances secreted by saprophytes; adverse temperature conditions; antagonistic effects of aquatic organisms and other factors. The processes of water self-purification proceed more intensively in the warm season, as well as in flowing waters of the rivers. Essential in the processes of water self-purification are the so-called saprophytic microflora and aquatic organisms. Some representatives of the microflora of water bodies have antagonistic properties to pathogenic microorganisms, which leads to the death of these microbes.
The simplest aquatic organisms, as well as zooplankton (crustaceans, rotifers, etc.), passing water through their intestines, destroy a huge number of bacteria. Bacteriophages trapped in a body of water also affect pathogens.
One of the important processes of self-purification of water is the mineralization of organic substances.
The first mineral product of the oxidation of nitrogen-containing organic substances is ammonium ion or ammonia. The presence of the latter in high concentrations, in the absence of nitrites and nitrates, indicates the freshness of pollution. Ammonia (ammonium nitrogen), as a rule, in the presence of oxidizing agents passes into nitrites, but these compounds are very unstable and, in the presence of oxygen, are oxidized to nitrates. Nitrates are the final substance for the mineralization of organic nitrogen-containing products.
Good aeration of water - enrichment of water with oxygen - provides activation of oxidative, biological and other processes, promotes water purification.
The rate of self-purification of water depends on many conditions: the amount of pollution entering the reservoir; its depths and water flow rates; water temperatures; the presence of dissolved oxygen in water; composition of microfauna and flora, etc.
The ability to self-purification is not unlimited, on the contrary, it is very limited.
Compounds of lead, copper, zinc, mercury, which can get into water bodies with drains, have a toxic effect on the organism of animals, and also help slow down the processes of self-purification of water and worsen its organoleptic properties.
In small ponds, with a significant amount of contaminants of a protein nature, intermediate substances of their decomposition (in particular, hydrogen sulfide, nitrites, diamines, etc.) that have high toxicity can accumulate in water.
Groundwater self-purification occurs due to filtration through the soil and due to the mineralization process, as a result, water is completely freed from organic pollutants and microorganisms.
The veterinary and sanitary inspection of water sources includes: monitoring its veterinary and sanitary condition and organizing protection in order to prevent possible water contamination with organic and other waste and sewage; organization of sanitary and laboratory control of water quality and taking into account the constancy of its quality depending on the seasons of the year and soil conditions; establishing the relationship between the good quality of drinking water and animal diseases (sanitary passport).
For open water bodies, an additional biochemical oxygen demand is determined for 5 days. (BOD3) in mg / l and dissolved oxygen in mg / l.
Regardless of the results of water analysis, only those water sources that can be provided or already have a sanitary protection zone (SOA) are allowed for use.
Under the SOA understand the area around the sources of water supply and waterworks, which must be respected specially established mode. The purpose of the organization of the SOA is to ensure the protection of water sources, waterworks and the surrounding area from pollution.
It is necessary to create SOA first of all near surface water sources that are easily accessible to pollution. This event is very important in terms of sanitary protection of underground water sources, since in the absence of SOA they may also be subject to pollution.
SOA for water pipelines that take water from open reservoirs consists of three belts: a strict regime, restrictions and observations.
The first zone of the SOA - a strict regime - covers the territory in which the water supply source is located and water intakes and waterworks are located. In this zone, the residence and the temporary finding of persons is prohibited. not working on waterworks. Construction is not allowed here, except for facilities related to the technical needs of the water supply system. The area of the strict regime belt when using underground sources is up to 1 ha with a radius of at least 50 m around the intake site. When using interlayer waters that are better protected, the belt may be limited to 0.25 ha.
The second belt of restrictions is the area immediately surrounding the water supply source. It is prohibited to use it for household needs (cattle graze, etc.).
The third belt of observations covers the territory adjacent to the territory of the second belt. Here, health authorities keep records of waterborne infections and constant monitoring to prevent the spread of infectious diseases through the water.
Standardization of water quality. Standardization of the quality of water used for watering farm animals and for livestock needs is one of the important preventive measures of veterinary medicine.
Water for watering animals in its composition and quality must meet the requirements of the current GOST “Drinking Water. Hygienic requirements and quality control.
The requirements of GOST, ensuring the safety of water in epidemic and epizootic relations, are based on indirect indicators - the number of saprophytes in 1 ml of water (no more than 100) and the number index (no more than 3).
The standards of the chemical composition of water are given in table. 13.5.
Water consumption standards. The amount of water consumed depends on the species, age, animal productivity, operating conditions., Nature of feeding, watering methods, temperature and water properties.
The average need for animals (estimated) in water is the following (per 1 kg of dry matter of feed, l): for horses - 2-3, cows - 4-6; fattening young - 3-4; pigs - 6-8; sheep - 2-3. Thirst occurs when the body loses water in an amount equal to 1% of body weight.
Water quality improvement carried out primarily due to cleaning and disinfection. Water purification is aimed at improving its organoleptic, physical, somewhat less chemical and even less biological (presence of microorganisms) properties.
For water purification must be equipped with appropriate facilities. Water purification involves bleaching and bleaching with coagulation, sedimentation and filtration. As a result of coagulation, flakes are formed. In this case, not only dispersed impurities are isolated from water, but also substances that are in a colloidal state. Aluminum sulphate is usually used as a coagulant, and also crude alumina is used, which contains 33% anhydrous aluminum sulphate. Aluminum oxychloride and sodium aluminate are also used as a coagulant.
To speed up the coagulation process, soft water that contains little calcium and magnesium bicarbonate should be alkalized with hydrated lime Ca (OH) 3 or soda. To do this, also apply high-molecular substances - flocculating. Thus, the polyacrylamide (PAA) preparation in a dose of 0.5-1.0 mg pa I l water speeds up the coagulation process and saves coagulant.
Settling - clarification of water by sedimentation suspended in it impurities. When water is at rest or moving at low speed, impurities under the action of gravity precipitate.
Water clarification is carried out in special structures - clarifiers of various types.
For further purification of water, filtering is used, which is carried out in special filter units through filtering material (sand). Usually, coagulated water, septic tanks or clarifiers are passed through the filters.
Disinfection of water can be carried out by one of four methods: thermal, with the help of oxidizing agents, oligodynamia (exposure to ions of noble metals), physical (ultrasound, radioactive radiation, ultraviolet rays). The most widely used as a disinfectant used oxidizers: chlorine, ozone, sodium hypochlorite.
Chlorination of water at large water supply stations is carried out with liquid (gaseous) chlorine, and at small water plants - with chlorine. Under the action of chlorine, most microorganisms in the water die.
Boiling is an easy and reliable way to disinfect small amounts of water.
For disinfection of water with ultraviolet bactericidal rays using lamps ДРТ-1000, ДБ-60, РКС-2.5 and installation ОВУ-6П, УОВ-5Н, etc.
In the practice of drinking water supply resort to special methods of water treatment in order to correct its salt composition. The most common deferrization, fluoridation and defluorination of water.
In recent years, livestock (especially in the poultry industry) use water activated by various physicochemical agents. Activated water has a molecular structure that is different from the usual one, has a high biological activity, stimulates metabolic processes, growth, development and productivity of animals.
Indicators Standards
Smell and taste at 20 0 С, points Not more than 2
Chromaticity, degrees 20
Transparency, cm (in Snellen's font) 30
Turbidity, mg / l Not more than 1.5
Active reaction, pH 6.0-9.0
Total hardness, mEq / l Not more than 7
Standards of bacterial purity of drinking water (GOST 2874-82)
Water is an inorganic, terrestrial, indispensable natural resource. A person can do without water, on average, about 5 days. Per person requires 2.75 liters of water per day for drinking and cooking. Without plumbing and sanitary, according to the norms, 30-50 liters of water per day for household and drinking purposes are required per person. In the presence of water supply, sewage and central hot water supply, the water consumption rate is 275-400 liters.
In addition to changing the taste, water with a large amount of salts dissolved in it affects the secretory and motor functions of the gastrointestinal tract, disrupts the water-salt balance in the body of animals, which leads to metabolic disorders and as a result - to various diseases, most often - urolithiasis . In the presence of a large amount of calcium and magnesium salts in water, it becomes hard, which causes both the disruption of the functioning of various body systems and certain difficulties in water supply and heating of livestock buildings (scale formation). There are stiffness temporary(disposable), which is caused by the presence of calcium and magnesium bicarbonates, easily precipitated during the hour-boiling process, and rigidity constant,associated with the content of sulfates in water, to reduce which liming is used.
An important indicator of water pollution is the presence of such compounds as nitrites and nitrates, especially of organic origin, which indicates the disintegration of organic compounds that have entered the water.
The total amount of organic compounds is determined by the amount of oxygen consumed for their oxidation, which determines such an indicator as oxidizedstsThe less oxidability, the less organic matter is in the water. The oxidizability of spring waters and waters of deep wells is 1-2 mg / l, flowing waters - 4, marsh waters - 8-20.
In addition to those mentioned, there is also such an indicator as biochemical oxygen consumptioncharacterizing the amount of oxygen dissolved in water. In 1 liter of water of open reservoirs at a temperature of 10-20 0 С contains from 5 to 20 mg of oxygen.
A good indicator of the purity of the water is the species composition of the fish fauna. So, the trout can be only in pure water, with the content of oxygen of 8-12 mg / l, crucians, carps live in more polluted water (4.8 mg / l). When the oxygen content of 1 mg / l is frozen fish.
Deep underground waters do not contain oxygen, but very soon they are enriched by it in the air when water is taken.
When characterizing water, its radioactivity should also be considered. Natural radioactivity of water depends on the presence of uranium salts in it (permissible concentration - not more than 1.7 mg / l), radium-226 (1.2 * 10 1 0 mg / l), strontium-90 (4.0 * 10 10 mg / l), etc. In the groundwater, the radioactivity may be somewhat overestimated, such water is used only for therapeutic purposes (for example, radon sources). Radioactive contamination of water bodies can occur as a result of the release of radioactive salts from the atmosphere, waste of enterprises that use radioactive substances.
Biological properties of water. On the basis of determining the inhabitants of the water of animal and vegetable origin, one can judge its quality. For example, saproby - organisms that live in water, slightly contaminated with organic matter, polysaproby - in highly polluted, and oligosaprobyy - only in clean water, enriched with oxygen.
Biologicalindicators determine the presence of aquatic organisms on the surface (plankton) and in the thickness (neuston) of water or located at the bottom of the reservoir, on the shores and on the surface of underwater objects (benthos).
Coley index - the number of individuals of E. coli, found in 1 liter (for solids in 1 kg) of the object under study; is determined by counting colonies of Escherichia coli grown on a dense nutrient medium when sowing a certain amount of the studied material, with subsequent recalculation to 1 l (kg). Koli-titer - This is the smallest amount of material studied, in which one E. coli was found. Total microbial number. As a criterion of bacteriological contamination, counting the total number of bacteria forming colonies (Colony Forming Units - CFU) in 1 ml of water is used. The resulting value is called microbial total. A high microbial number indicates a general bacteriological contamination of water and a high probability of the presence of pathogenic organisms.
The state standard in assessing the biological properties of water and its safety in the epidemiological and epizootic relation takes into account both the total number of bacteria in it and the number of E. coli. According to the number of bacteria and the titer of Escherichia coli, bacteriological contamination of water can be judged. In 1 liter of good quality water, no more than 100 bacteria and 3 intestinal sticks are allowed; in water from wells and river water, 400–1000 and not more than 10, respectively.
Consequently, natural water is far from always able to satisfy the physiological and hygienic needs of animals; constant monitoring of its quality and timely measures for its improvement and disinfection are necessary.
Characteristicwater sourcesand themscore.Depending on the origin distinguish atmospheric, surface and groundwater.
Atmospheric waterfall to the ground in the form of rain, snow, fog, hail. This water absorbs from the atmosphere like various gases, atincluding emissions from chemical plants, microbes and other mechanical impurities, this water is not suitable for drinking.
Surface water -these are rivers, streams, lakes, swamps, etc. This water is unsuitable for raw water drinking, it can be used only after preliminary treatment.
The groundwater - waters located in the underlying layers of the soil. They are divided into super-watering (at a depth of 3 m), groundwater (depth of over 7 m) and artesian (up to 100 m or more). The headwater is unsuitable for drinking because of its possible contamination, but the groundwater and especially artesian water is recommended for drinking almost without cleaning and disinfection.
