ANALYSIS OF WATER QUALITY FOR PRODUCTION AND ITS CLEANING
[3. Технічні науки]
Автор: Sergiy Kunytskyi, PhD, National University of Water and Environmental Engineering, Rivne; Natalia Ivanchuk, PhD, National University of Water and Environmental Engineering, Rivne; Sergiy Shatnyi, PhD, National University of Water and Environmental Engineering, Rivne; Oleg Pinchuk, PhD, National University of Water and Environmental Engineering, Rivne; Natalia Minaeva, PhD, National University of Water and Environmental Engineering, Rivne
The issue of providing the production and household needs of the population of Ukraine with water of appropriate quality has not lost its relevance for a long time. However, during the last decade, the problem has significantly worsened due to changes in the climatic conditions of the territory. Many rural settlements have experienced a shortage of drinking water during the summer months .
In world practice, a large number of technologies, methods and structures have been implemented for the preparation of spring waters. The authors Meng D., Peng X., Żurek A., Chen W., Ying Y., Li Q., Denisov S.E., Son S., Ying W., Wang L. considered water treatment technologies using filters with membranes [2, 3], heavy granular [4, 5] and floating loads .
The cost and complexity of preparing water in accordance with the requirements set by the sanitary and epidemiological service depend on the method of its purification. The choice of the water treatment method is based on the study of water quality indicators of the water source (chemical composition of water)  obtained as a result of analyzes and a number of other indicators.
Water supply in the southern and eastern parts of Ukraine is carried out mostly from surface sources, in particular rivers. Surface waters have a fairly significant capacity, but their physical and chemical composition is polluted with toxic chemicals, oil products, salts of heavy metals, phenols, biogenic substances, etc.
Groundwater is better protected from runoff pollution and therefore in many countries of the world has priority as a source of economic and drinking water supply. For example, in Italy they make up 93% of total water consumption from water sources, in Lithuania - 95%, Germany - 91%, Switzerland - 70%, and in Ukraine - only 25%. More than 50% of underground water in Ukraine has an elevated iron content .
When using such waters, the need for iron removal, demanganization and defluoridation most often arises. An excess of manganese gives water a brown color and taste, diseases of the bone system. Water with a high content of iron (more than 0.2 mg/l) and manganese (more than 0.1 mg/l) causes inconvenience in everyday life, unpleasant taste .
Methods of deironing water exclude their equivalence in terms of reliability, manufacturability, economy, simplicity, and field of application. The method of iron removal is chosen depending on the chemical composition of the water, degree of iron removal, plant productivity, and technological tests. Most often, a reagent-free method is used for deironing groundwater, as it is simpler and cheaper .
Reagentless and reagent methods are also called physicochemical methods, which involve the introduction of iron oxidizers. In the first case, this oxidizer is air oxygen, and in the second, solutions of chemical oxidizers are introduced into the water. Iron oxidation can be carried out by deep and simplified aeration .
A set of measures related to the removal of dissolved gases from water is called water degassing. There are physical and chemical methods of water degassing.
The essence of physical methods of degassing:
- water containing gas is brought into contact with air if the partial pressure of this gas in the air is close to zero;
- conditions are created in which the solubility of gas in water becomes very low.
Using the first method (aeration of water), free carbon monoxide (IV) and hydrogen sulfide are usually removed, since the partial pressure of these gases in atmospheric air is close to zero. The second method is usually used when water is deoxygenated. In this case, due to the significant partial pressure of oxygen in atmospheric air, it is not possible to remove oxygen by aerating water, so the water is brought to a boil, then the solubility of all gases in it drops to zero. For this, either heating water (in thermal deaerators) or lowering the pressure to the value at which water boils without additional heating in vacuum deaerators is used.
Chemical methods are based on certain reactions that result in the chemical bonding of dissolved gases. These methods are implemented by introducing reagents into the treated water or by filtering it through special loads.
To remove dissolved gases from water, several types of degasser are used: film degasser with various types of nozzles, which work in counterflow conditions of degassed water and air supplied by a fan; film ones that work without forced air supply; jet-film (contact cooling towers); bubbling; vacuum
In water treatment technology, film degassers are mainly used to remove gases (except oxygen), and vacuum degassers or thermal deaerators are used to deoxygenate water. Bubble degassers are used only in exceptional cases due to their relatively high operating cost (high consumption of electricity for air compression).
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