Water, its role in nature, types of water pollution sources.
Water is inorganic compound formed by two elements (two atoms of hydrogen and one atom of oxygen). Pure water has no smell and color, as well as an explicit taste. In normal condition, water is presented in the form of liquid.
Water has a direct influence on the formation of weather and climate, is actively involved in biochemical reactions of living organisms. For example, in animals, the proportion of water is about 60-75 %, in newborns, 70-80 %, and in embryos up to 87-97 %. Thus, water plays a major role in maintaining life on Earth.
A water feature is the stay in an unstable (metastable) state under certain conditions (this state is called supercooled liquid, the supersaturated vapor, superheated liquid).
Water is a natural solvent, such as organic compounds and inorganic substances. In a natural state the water contains salts of different substances and compounds, dissolved gases.
The content of cations of calcium and magnesium are distinguished: soft and hard water.
Isotopic molecules: ordinary water (light), deuterium water (heavy), tritium water (heavy).
The salt content of: fresh water and sea water.
There are such things as water:
– waste water;
– surface water;
– storm water;
– drinking water;
– mineral water;
– brackish water;
– distilled water,
– sterile water (for medical injection);
– abnormal or modified waterwith unique properties for scientific experiments.
The main indicators of the quality of water include: physical, chemical, biological and bacteriological indicators.
Physical quality indicators identified by odor, taste, color, presence of suspended matter.
During evaluation of the odor using a 5-point scale, thus it appears as dominated by one of the presented grounds: swamp, putrid, aromatic, earthy, fishy. Through laboratory shake flasks with the contents evaluate the odor intensity of the sample. Check the smell of water is relevant in different situations, for example, when assessing treated water. The presence of smell in treated water indicates poor quality of cleaning or incomplete removal of special reagents (chlorine).
Check the colour of water in quantitative terms is carried out by colorimetry, by comparing the samples with a scale of standards.
A qualitative comparison of samples is carried out with distilled water on a white background in natural lighting. Upon detection of coloring the water point identified by color (brown, light yellow). If the compared samples are identical, then the conclusion indicates that the sample is colorless.
Water transparency indicates the degree of contamination of the sample in suspended and colloidal (maximally fragmented) state.
Turbidity indicates the presence in the test sample a sufficient amount of organic/inorganic contaminants. Suspended solids are separated through filtration, and then evaluated their prevalence in the study sample. Turbidity of water is determined by gravimetric method.
The presence of solids, the conclusion about the presence of nonvolatile substances in the wastewater. The study is conducted using gravimetric method. The method allows to accurately determine the amount of organic matter that are suspended in the sample.
Chemical quality indicators of water allow to identify alkalinity, acidity, hardness, conductivity, presence of organic substances and dissolved oxygen.
The alkalinity of water is determined by the presence of alkali salts and free alkalis. Control alkaline environment of the wastewater is important not only at the entrance to the treatment plant, but on the way out. Only under the condition of neutrality environment (pH ~ 6.5 and 8.5) is guaranteed by the natural microorganisms that provide biological treatment of wastewater.
The acidity of the water is the most important indicator is relevant when discharge into reservoirs of acid waters. Prior to discharge into the reservoir of acid wastewater should be neutralized acidity. The acidity level is determined by the presence in water of acid salts and free carbonic acid. Indicator of the acidity of the water is the substance phenolphthalein.
The nitrogen content in the water is checked to determine ammonium nitrogen (NH+4), nitrate (NO–3) nitrogen and nitrite (NO–2).
Oxidation of water due to the chemical reaction of oxidation of some quick acting inorganic substances (Fe2+, hydrogen sulphide, sulphite, nitrite) and organic compounds. Ultimately, biochemical oxygen demand indicates how much oxygen was used in oxidation of organic substances contained in 1 liter of water.
Chemical oxygen demand (abbreviated COD) allows to make a conclusion about how much water contains organic substances that are prone to oxidation aggressive oxidation agents.
Biochemical oxygen demand (abbreviated as BOD) allows to evaluate the degree of pollution of wastewater by aerobic microorganisms, reacts violently with oxygen environment. The indicator BOD is determined using the iodometric method.
The total hardness of water is formed by two indicators: carbonate and non-carbonate hardness. Carbonate hardness indicates the level of concentration in water of bicarbonates of magnesium and potassium. Non-carbonate rigidity demonstrates the presence in water of sulphate of magnesium and potassium and chlorides. The total combination of indicators a single indicator expresses the overall stiffness.
Biological quality indicators demonstrate the presence in water of hydroflora and gidrobiontov. Hydroflora is determined by microfiche and macrophytes. To microvitum include algae and macrophytes associated with aquatic vegetation. With the withering away of macrophytes in water increases the level of organic substances. The value of makrofitov is that protozoa algae absorb dissolved carbon dioxide, releasing the oxygen.
To hydrobionical applies three kinds of alive environment: plankton residing in the water column; the inhabitants of the bottom of the water column (bentos); animals inhabiting the surface layer of water (neisia).
Bacteriological quality indicators characterize the safety (neutral) water medium in here regarding pathogens especially Escherichia coli. To determine the degree of contamination of water by pathogenic microorganisms (E. coli) is used IF the value of the index. The definition of a measure on a sample taken 1 liter of water.
Water, except a liquid state can be found in other States of aggregation. In the solid state water is presented in the form of ice, frost and snow grains. In the gaseous state in the form of steam.
At normal atmospheric pressure, water turns into water vapor at 100°C, and transformered into ice at 0°C. Upon pressure increase the boiling point of the aqueous medium increases, and Vice versa, when the pressure drops, the boiling point falls.
Water can simultaneously be in different combined conditions, for example: sea water and iceberg, rivers and glaciers on the earth’s surface, water vapor and clouds.
Water covers 71% of the planet’s surface while in the oceans, seas, rivers, lakes and glaciers. In the earth’s mantle is 10-12 times more water than in the waters of the world ocean. A large part is salt water, unsuitable for drinking and cultivation of crops in agriculture. The share of fresh water accounts for a small part: in glaciers contains 1,81%, in underground waters was 0.63%, in rivers and lakes – 0,009%.
It is considered that the average water density equal to 1000 kg/cubic meter, which corresponds to 1000 g/liter. To be more precise, the density of water is maximum and is equal to the value 999,972 kg/cubic meter at a temperature of from 3.8 to 4.2°C. For example, at a temperature of 25°C the density of water is 997 kg/ cubic meter.
Substantial change the density of water causes the change of the aggregate state. The density of ice varies 916-920 kg/cubic meter, and the density of water vapor is only a few hundredths of a kilogram per cubic meter.
The boundary between liquid and water vapor disappears at the critical temperature, component 374,12° C.
Land-based sources are represented by rivers, natural ponds and artificial reservoirs.
Underground water sources are presented: storage water artesian pressure type and mizhplastovi water resource unconfined type.
Atmospheric water contain various impurities and dissolved gases, but also significantly contaminated. Precipitation is typical for the phenomenon of acid rain. Atmospheric water definitely subject to disinfection and cleaning.
Open water sources are unsafe to use because it can contain toxic substances accumulated as a result of the inflow of sewage. In open water can “bloom” water, and the organic go overboard. Open sources are characterized by low transparency, high salinity. To water from such sources can be used for drinking, is required to carry out its cleaning and disinfection.
Underground water reserves are grouped into soil water, ground water, underground storage mizhplastovi water (pressure and non-pressure).
The most secure composition is the water from artesian sources, which can be used without pre-treatment. Water obtained from artesian wells, odorless, transparent, colorless. It lacks the microorganisms and organic matter. Feature of water from an artesian well is an increased level of mineralization.
Without treatment and disinfection, you can also drink water obtained from an underground aquifer is not pressurized. Such a water resource is at a sufficient depth between two waterproof layers. Seepage in mizhplastovi water storage surface water and atmospheric moisture is excluded.
To provide the population with clean water is practiced by the use of two water supply systems: centralized system and decentralized (local) system.
Central water system available in any city. The system includes a Central water system with all elements and network communications pipe designed to deliver water to the consumer.
Central water supply includes: water intake, pump station, treatment plant, tanks for clean water, a pressure tower. Purified and disinfected water through a network of pipes under pressure is supplied to every consumer (household).
Local water supply is arranged in places where the number of inhabitants slightly. The water is taken usually from an underground source by means of pumps.
When selecting the source of water for water supply priority is given to cross water-bearing layers of the artesian type. Water from such a source meets the required sanitary standards and is fully usable.
The choice of water source is based on sanitary-hygienic norms and environmental standards. The consumer should get a quality product that will not cause harm to his health. Therefore, when choosing an optimal source of water supply, the decision is made in favor of cross-aquifers with high hygienic indicators. If the artesian reservoirs is not available, then the choice is made in favor of cross-unconfined layers. In third place in terms of reliability are the ground waters of the first aquifer. If it is impossible to access underground aquifers cross and dirt layers choice is made in favor of open water, but in this case it is necessary to devise a system of purification and disinfection of water.
Sources of pollution of natural waters to date are: chemical, biological and physical sources.
Chemical sources of pollution include industrial processes, transportation and agricultural production.
Biological sources of pollution include viruses, bacteria, yeast and pathogens.
Physical sources of pollution include the dumping of heat into water, radioactive contamination, etc.
Specific pollutants are the following substances:
resins, fats, phenol, sulphates (products of wood);
– derivative of oil refining;
products of chemical industry;
– mineral substances, such as products used in mining and coal industry;
– organic dyes and substances.
In their composition, wastewater from industrial enterprises will be classified as domestic, industrial and atmospheric.
Domestic industrial waste water – product showers and toilets of production and administrative buildings.
Industrial water – water used for technological processes in the enterprise.
Atmospheric water – the result of rain and fallen and then melted snow.
Industrial waste water are divided into two sub – polluted and relatively clean water.
Industrial pollution of water is evident in the increase of salts of heavy metals, occurrence of radioactive elements, pathogenic microorganisms, reducing oxygen.
Contaminated water at the company are divided into three subgroups:
– water, saturated with mineral admixtures (metallurgy, engineering, coal mining);
– water, saturated with organics (food industry, dairy factories, pulp and paper mills, processing plants fish and seafood);
– water saturated with inorganic impurities (oil refineries, mills and textile industry).
Water can be applied in these and similar areas such as:
– cultivation of agricultural crops, especially in dryland areas;
– as a solvent of organic and inorganic substances;
– how effective coolant for heating and operation of the circuits of nuclear power plants;
– as a neutron moderator in the conduct of nuclear reactions in nuclear power plants;
– when water-jet cutting of rocks, different materials and metals;
– when fighting fires;
– to meet the needs of a living organism in the water.
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