Mineralization, total salt content (TDS)
- Most rivers have mineralization from several tens of milligrams per liter to several hundred. Their conductivity varies from 30 μS / cm to 1500 μS / cm.
- Mineralization of groundwater and salt lakes varies in the range from 40-50 mg / dm 3 to 650 g / kg (the density in this case is already significantly different from unity).
- The specific electrical conductivity of atmospheric precipitation (with mineralization from 3 to 60 mg / dm 3) is 20-120 μS / cm.
Many industries, agriculture, drinking water supply enterprises impose certain requirements on the quality of water, in particular, to mineralization, since waters containing a large amount of salt negatively affect plant and animal organisms, production technology and product quality, cause scale formation on the walls boilers, corrosion, soil salinization.
Classification of natural waters by mineralization.
In accordance with the hygienic requirements for the quality of drinking water, the total mineralization should not exceed 1000 mg / dm 3. By agreement with the Rospotrebnadzor authorities, for a water supply system that supplies water without appropriate treatment (for example, from artesian wells), an increase in mineralization up to 1500 mg / dm 3 is allowed).
Specific conductivity of water
Specific conductivity is a numerical expression of the ability of an aqueous solution to conduct electric current. The electrical conductivity of natural water depends mainly on the concentration of dissolved mineral salts and temperature. Natural waters are mainly solutions of mixtures of strong electrolytes. The mineral part of the water consists of ions Na +, K +, Ca 2+, Cl -, SO 4 2-, HCO 3 -. These ions determine the electrical conductivity of natural waters. The presence of other ions, for example, Fe 3+, Fe 2+, Mn 2+, Al 3+, NO 3 -, HPO 4 2-, H 2 PO 4 - does not greatly affect the electrical conductivity, if these ions are not contained in water in significant quantities (for example, below the outflows of industrial or domestic wastewater). By the values of the electrical conductivity of natural water, one can approximately judge the mineralization of water using pre-established dependencies. Difficulties arising in assessing the total content of mineral substances (mineralization) by specific electrical conductivity are associated with:
- unequal electrical conductivity of solutions of various salts;
- an increase in electrical conductivity with increasing temperature.
The normalized values of mineralization approximately correspond to the specific electrical conductivity of 2 mS / cm (1000 mg / dm 3) and 3 mS / cm (1500 mg / dm 3) in the case of both chloride (in terms of NaCl) and carbonate (in terms of CaCO 3 ) mineralization. The value of specific electrical conductivity serves as an approximate indicator of their total concentration of electrolytes, mainly inorganic, and is used in programs for observing the state of the aquatic environment to assess the salinity of waters. Specific electrical conductivity is a convenient summary indicator of anthropogenic impact.
Temperature
The water temperature is the result of several simultaneously occurring processes, such as solar radiation, evaporation, heat exchange with the atmosphere, heat transfer by currents, turbulent mixing of water, etc. intensity and depth of mixing. Daily temperature fluctuations can be several degrees and usually penetrate to shallow depths. In shallow water, the amplitude of water temperature fluctuations is close to the difference in air temperature. The requirements for the water quality of reservoirs used for swimming, sports and recreation indicate that the summer water temperature as a result of the discharge of wastewater should not increase by more than 3 ° C compared to the average monthly temperature of the hottest month of the year over the past 10 years. In reservoirs for fishery purposes, an increase in water temperature as a result of the discharge of wastewater is allowed by no more than 5 ° C compared to the natural temperature. Water temperature is the most important factor affecting the physical, chemical, biochemical and biological processes occurring in the reservoir, on which the oxygen regime and the intensity of self-purification processes largely depend. Temperature values are used to calculate the degree of water saturation with oxygen, various forms of alkalinity, the state of the carbonate-calcium system, in many hydrochemical, hydrobiological, especially limnological studies, in the study of thermal pollution.
The most valuable information about the effect of low concentrations of calcium in drinking water on the whole population of people was obtained in studies carried out in the Soviet city of Shevchenko (now Aktau, Kazakhstan), where desalination plants were used in the city water supply system (the source of water is the Caspian Sea). The local population showed a decrease in the activity of alkaline phosphatase, a decrease in the concentration of calcium and phosphorus in plasma and an increase in decalcification of bone tissue. These changes were most noticeable in women, especially pregnant women, and depended on the length of residence in Shevchenko. The need for calcium in drinking water is also confirmed in a one-year experiment on rats who were provided with a completely adequate diet in terms of nutrients and salts, but were watered with distilled water, to which was added 400 mg / L of calcium-free salts and one of these calcium concentrations: 5 mg / L, 25 mg / L or 50 mg / L. In rats that received water with 5 mg / L calcium, a decrease in the functionality of thyroid hormones and other related functions was found compared to the rest of the animals participating in the experiment.
It is believed that a general change in the composition of drinking water affects human health after many years, and a decrease in the concentration of calcium and magnesium in drinking water affects health almost instantly. So, the inhabitants of the Czech Republic and Slovakia in 2000-2002 began to actively use reverse osmosis systems in their apartments for additional purification of city water. Over the course of several weeks or months, local doctors were flooded with a stream of patients with complaints indicating acute magnesium (and possibly calcium) deficiency: cardiovascular disorders, fatigue, weakness, and muscle cramps.
3. The risk of a deficiency of vital substances and microelements when drinking low-mineralized water.
Although drinking water, with rare exceptions, is not the main source of vital elements for humans, it can make a significant contribution to their intake for several reasons. First, the food of many modern people is a rather poor source of minerals and trace elements. In the case of borderline deficiency of any element, even a relatively low content of it in consumed drinking water can play a corresponding protective role. This is due to the fact that elements are usually present in water in the form of free ions and therefore are more easily absorbed from water compared to food, where they are mainly found in complex molecules.
Animal studies also illustrate the importance of micro-sufficiency in some of the elements present in water. So, according to V.A.Kondratyuk's data, a slight change in the concentration of trace elements in drinking water dramatically affects their content in muscle tissue. These results were obtained in a 6-month experiment in which rats were randomized into 4 groups. The first group was given tap water, the second - low-mineralized water, the third - low-mineralized water with the addition of iodide, cobalt, copper, manganese, molybdenum, zinc and fluoride. The last group received low-mineralized water with the addition of the same elements, but ten times higher concentration. It was found that low-mineralized water affects the process of hematopoiesis. In animals that received demineralized water, the average hemoglobin content in erythrocytes was 19% lower than in rats that were given tap water. Differences in the hemoglobin content were even higher compared to animals that received mineral water.
Recent epidemiological studies in Russia, carried out among population groups living in areas with different salinity of water, indicate that low-mineralized drinking water can lead to hypertension and coronary heart disease, stomach and duodenal ulcers, chronic gastritis, goiter, pregnancy complications and a variety of complications in neonates and infants, including jaundice, anemia, fractures, and growth impairments. However, the researchers note that it remained unclear for them whether it is drinking water that has such an effect on health, or whether it is all about the general environmental situation in the country.
Answering this question, G. F. Lutai conducted a large cohort epidemiological study in the Ust-Ilimsk district of the Irkutsk region in Russia. The study focused on the morbidity and physical development of 7658 adults, 562 children and 1582 pregnant women and their newborns in two districts supplied with water differing in total mineralization. Water in one of these areas had a total salt content of 134 mg / l, of which calcium 18.7 mg / l, magnesium 4.9 mg / l, bicarbonates 86.4 mg / l. In another area, the total mineralization of water was 385 mg / L, of which calcium 29.5 mg / L, magnesium 8.3 mg / L and hydrocarbons 243.7 mg / L. The content of sulfates, chlorides, sodium, potassium, copper, zinc, manganese and molybdenum in water was also determined. The population of these two districts did not differ from each other in social and ecological conditions, time of residence in the respective regions, and food habits. Among the population of the area with less mineralized water, higher incidence rates of goiter, hypertension, ischemic heart disease, gastric and duodenal ulcers, chronic gastritis, cholecystitis and nephritis were revealed. Children living in this area showed slower physical development, manifestation of growth abnormalities. Pregnant women were more likely to suffer from edema and anemia. Newborns in this area were more susceptible to disease. The lowest incidence was observed in areas with hydrocarbonate water, which has a total mineralization of about 400 mg / l and contains 30-90 mg / l calcium and 17-35 mg / l magnesium. The author came to the conclusion that such water can be considered physiologically optimal.
4. Washing out nutrients from food prepared in low-mineralized water.
It was found that when softened water is used for cooking, there is a significant loss of food products (meat, vegetables, cereals) of micro and macro elements. Up to 60% of magnesium and calcium, 66% of copper, 70% of manganese, 86% of cobalt are washed out from the products. On the other hand, when hard water is used for cooking, the loss of these elements is reduced.
Since most nutrients are absorbed through food, the use of low-mineralized water for cooking and food processing can lead to marked deficiencies in some important micronutrients and macronutrients. The current menu for most people usually does not contain all the essential elements in sufficient quantities, and therefore any factor that leads to the loss of essential minerals and nutrients during the cooking process further exacerbates the situation.
5. Possible increase in the intake of toxic substances into the body.
Low-mineralized, and especially demineralized, water is extremely aggressive and is capable of leaching heavy metals and some organic substances from the materials with which it comes into contact (pipes, fittings, storage tanks). In addition, the calcium and magnesium contained in the water have a somewhat antitoxic effect. Their absence in drinking water, which also got into your tin mug through copper pipes, will easily lead to poisoning with heavy metals.
Among the eight cases of drinking water intoxication reported in the United States in 1993-1994, there were three cases of lead poisoning in infants, whose blood levels were found to be 1.5, 3.7 and 4.2 times higher, respectively. In all three cases, lead was leached out of the lead-soldered seams in the reverse osmosis drinking water storage tanks used to bred baby food.
It is known that calcium and, to a lesser extent, magnesium have antitoxic activity. They prevent heavy metal ions such as lead and cadmium from being absorbed into the blood from the intestine by competing for binding sites. Although this protective effect is limited, it cannot be discarded. At the same time, other toxic substances can enter into a chemical reaction with calcium ions, forming insoluble compounds and, thus, losing their toxic effect. Populations in areas supplied with low-salinity water may be at an increased risk of toxicity compared to populations in regions where regular hard water is used.
6. Possible bacterial contamination of low-mineralized water.
This point in the original article is a little far-fetched, but still. Any water is susceptible to bacterial contamination, which is why pipelines contain a minimum residual concentration of disinfectants - for example, chlorine. It is known that reverse osmosis membranes are capable of removing practically all known bacteria from water. However, reverse osmosis water also needs to be disinfected and retained in it the residual concentration of the disinfectant in order to avoid secondary contamination. An illustrative example is an outbreak of typhoid fever caused by reverse osmosis treated water in Saudi Arabia in 1992. They decided to abandon the chlorination of reverse osmosis water, because, in theory, it was deliberately sterilized by reverse osmosis. The Czech National Institute of Public Health in Prague tested products intended to come into contact with drinking water and found, for example, that pressure tanks in household reverse osmosis plants are susceptible to bacterial overgrowth.
1. According to the WHO report 1980 (Sidorenko, Rakhmanin).Drinking water with low mineralization leads to the leaching of salts from the body. Since side effects, such as a violation of water-salt metabolism, were observed not only in experiments with completely demineralized water, but also when using low-mineralized water with a total salt content in the range from 50 to 75 mg / l, the group of Yu.A. Rachmanin in their report recommended for WHO to set the lower bar for the total mineralization of drinking water at the level of 100 mg / l. The optimal level of salinity of drinking water, according to these recommendations, should be about 200-400 mg / l for chloride-sulphate waters and 250-500 mg / l for hydrocarbonate waters. The recommendations were based on extensive experimental studies in rats, dogs and human volunteers. Moscow tap water was used in the experiments; desalinated water containing approximately 10 mg / l of salts; laboratory prepared water containing 50, 100, 250, 300, 500, 750, 1000 and 1500 mg / l of dissolved salts with the following ionic composition:
- among all chloride anions 40%, hydrocarbonate anions 32%, sulfates 28%;
- among all cations sodium 50%, calcium 38%, magnesium 12%.
In addition to the level of total mineralization, this report substantiates the minimum calcium content in drinking water - not less than 30 mg / l. This requirement was introduced after studying the critical effects resulting from hormonal changes in calcium and phosphorus metabolism and a decrease in bone mineralization when drinking water deprived of calcium. The report also recommends maintaining the content of bicarbonate anions at a level of 30 mg / l, which helps to maintain acceptable organoleptic characteristics, reduce corrosivity and create an equilibrium concentration for the recommended minimum calcium concentration.
More recent research has led to more precise requirements. So, in one of them, the effect of drinking water containing various concentrations of hardness salts on the health of women aged 20 to 49 in four cities of Southern Siberia was studied. The water in city A had the lowest content of these elements (3.0 mg / L calcium and 2.4 mg / L magnesium). The water in city B was harder (18.0 mg / L calcium and 5.0 mg / L magnesium). The highest hardness was observed in cities C (22.0 mg / L calcium and 11.3 mg / L magnesium) and D (45.0 mg / L calcium and 26.2 mg / L magnesium). Women living in cities A and B were more likely to be diagnosed with cardiovascular disease (based on ECG data), higher blood pressure, somatoform autonomic dysfunctions, headache, dizziness, and osteoporosis (based on X-ray absorptiometry) compared to with those in cities C and D. These results show that the minimum magnesium content in drinking water should be 10 mg / l, and the minimum calcium content can be reduced to 20 mg / l (compared with the 1980 WHO recommendations).
Based on the currently available data, various researchers have finally come to the following recommendations regarding the optimal hardness of drinking water:
A. magnesium - not less than 10 mg / l, optimally about 20-30 mg / l;
b. calcium - not less than 20 mg / l, optimally 40-80 mg / l;
v. their sum (total hardness) is 4-8 meq / l.
At the same time, magnesium is limited from below in its effect on the cardiovascular system, and calcium - as a component of bones and teeth. The upper limit of the optimal range of hardness was set based on concerns about the possible influence of hard water on the occurrence of urolithiasis.
Effects of hard water on kidney stone formation
Under certain certain conditions, solutes contained in urine can crystallize and be deposited on the walls of the renal cups and pelvis, in the bladder, and also in other organs of the urinary system.According to the chemical composition, several types of urinary calculi are distinguished, however, due to the hardness of the water, mainly phosphates and oxalates are of interest. In case of impaired phosphorus-calcium metabolism or in the case of vitamin D hypervitaminosis, phosphate stones can form. The increased content of oxalic acid salts in food - oxalates - can lead to the appearance of oxalate calculi. Both calcium oxalate and calcium phosphate are insoluble in water. By the way, there are a lot of oxalates not only in sorrel, but also in chicory, parsley, beets. And oxalates are also synthesized by the body.
The effect of water hardness on the formation of urinary calculi is difficult to determine. Most studies evaluating the effect of water hardness on the appearance and development of urolithiasis (urolithiasis) use data from inpatient medical institutions. In this sense, a study by Schwartz et al. , significantly different in that all data was collected on an outpatient basis, while the patients remained in their natural environment and went about their daily activities. This paper presents the largest cohort of patients to date, which makes it possible to assess the effect of water hardness on various components of urine.
Scientists have processed a vast amount of material. The United States Environmental Protection Agency (EPA) has provided geo-referenced information on the chemical composition of drinking water in the United States. This information was combined with a national database of outpatients with urolithiasis (it contains the patient's zip code, so geo-referencing was possible). Thus, 3270 outpatients with calcium calculi were identified.
In the minds of most people, increased water hardness is synonymous with an increased risk of developing urolithiasis (kidney stones are a special case of urolithiasis). The mineral content, and especially calcium, in drinking water appears to be perceived by many as a health hazard.
Despite these common concerns about water hardness, no studies support the suggestion that drinking hard water increases the risk of urinary calculi.
Sierakowski et al. examined 2,302 medical reports from inpatient hospitals scattered throughout the United States, and found that patients who lived in areas supplied with hard water had a lower risk of urolithiasis. Similarly, in the cited work, it was found that the hardness of drinking water is inversely proportional to the incidence of urolithiasis.
In this study, the number of episodes of urolithiasis was slightly higher in patients living in areas with softer water, which is consistent with the data of other authors, but contrary to public perception. It is known that in some cases, such as in individuals with hypercalciuria, increased oral calcium intake can aggravate the formation of urinary stones. In patients with hyperoxaluric calcium nephrolithiasis, increased oral calcium administration, on the other hand, can successfully inhibit stone formation by binding oxalic acid salts with calcium in the intestine and thus limiting the flow of oxalates into the urinary system. The intake of calcium from drinking water has the potential to inhibit the formation of calcium urinary calculi in some patients and promote the formation of stones in others. This theory was tested by Curhan et al., Who evaluated the effects of calcium intake in 505 patients with recurrent calculus. After 4 years of follow-up, the group of patients taking calcium had the least number of episodes of urinary stones. The researchers concluded that high dietary calcium intake lowers the risk of symptomatic urolithiasis.
Despite public concerns about the potential lithogenesis of hard tap water, existing scientific evidence suggests that there is no relationship between water hardness and the prevalence of urinary stones. There appears to be a correlation between water hardness and urinary calcium, citrate and magnesium levels, but the significance of this is unknown.
By the way, the author gives an interesting comparison: the consumption of one glass of milk can be equivalent to two liters of tap water in terms of calcium content. So, according to the US Department of Agriculture (USDA), 100 g of milk contains 125 mg of calcium. The same amount of water from the city water supply contains only about 4-10 mg of calcium.
Conclusion
Drinking water should contain minimum concentrations of some essential minerals. Unfortunately, too little attention has always been paid to the beneficial properties of drinking water. The main focus was on the toxicity of untreated water. The results of recent studies aimed at establishing the optimal mineral composition of drinking water should be heard not only by public and private structures responsible for the water supply of entire cities, but also by ordinary people who abuse water treatment systems at home.Drinking water produced by industrial desalination plants is usually remineralized, but reverse osmosis water is usually not mineralized at home. However, even with the salinity of desalinated waters, their chemical composition may remain unsatisfactory in terms of the needs of the body. Yes, calcium salts can be added to the water, but it will not contain other essential trace elements - fluorine, potassium, iodine. In addition, desalinated water is more mineralized for technical reasons - to reduce its corrosiveness, and the importance of substances dissolved in water for human health is usually not thought about. None of the methods used for remineralization of desalinated water can be considered optimal, since only a very narrow set of salts is added to the water.
The effect of hard water on kidney stone formation has not been scientifically proven. There are concerns that increased consumption of oxalic acid salts or phosphates together with calcium may lead to crystallization of insoluble calcium salts of phosphoric or oxalic acids in the organs of the urinary system, but the body of a healthy person, according to existing scientific data, is not subject to such a risk. At risk may be persons suffering from kidney disease, vitamin D hypervitaminosis, impaired calcium-phosphorus, oxalate, citrate metabolism, or eating significant amounts of oxalic acid salts. It has been established, for example, that a healthy body is capable of processing up to 50 mg of oxalates per 100 g of food without any consequences for itself, but spinach alone contains 750 mg / 100 g of oxalates, so vegetarians may be at risk.
In general, demineralized water is no less harmful than waste water, and in the 21st century it is high time to move away from standardizing water quality indicators only from above. Now it is necessary to establish also the lower limits of the content of minerals in drinking water. Physiologically optimal is only a narrow corridor of concentrations and composition of drinking water. The information currently available on this issue can be presented in the form of a table.
Table 1. Optimal mineralization of drinking water
| Element | Units | Minimum content | Optimal level | Maximum level, SanPiN 2.1.4.1074-01 or * WHO recommendation |
|---|---|---|---|---|
| Total mineralization | mg / l | 100 | 250-500 for hydrocarbonate waters 200-400 for chloride-sulphate waters |
1000 |
| Calcium | mg / l | 20 | 40-80 | - |
| Magnesium | mg / l | 10 | 20-30 | - Add tags |
According to the indicators determined in SanPiN, the total mineralization of drinking water is normal - that is, the values in maximum permissible concentrations (MPC) - should remain within 1000 mg / liter. In the case of a separate consideration of the epidemiological situation in a certain settlement or for a specific water supply system, by order of the state chief sanitary doctor, this indicator can be increased to 1500 mg / liter. These restrictions were established by organoleptic characteristics. However, optimum values fall within the range of 200 to 400 mg of solids per liter.
The parameter of total mineralization itself in the SanPiN table is accompanied by a postscript in brackets: "dry residue". In this case, the value of the dry residue may not coincide with the actual salinity, since the method for determining the dry residue by evaporation and weighing the residue does not take into account some volatile dissolved organic compounds. As a result, the difference in values can be up to 10%.
General mineralization: concept and categories
Under the total mineralization it is customary to understand the total content of substances dissolved in water, which determines the second name "salt content", which is also legitimate to use, since dissolved substances are in water in the form of salts of potassium, magnesium, sodium, calcium sulfates, chlorides, hydrocarbonates. These are mainly inorganic substances and organic in a small amount.
Surface waters, all other things being equal, in the assessment of salinity have a lower sediment than groundwater. Therefore, underground ones have a salty (sometimes bitter) taste. In addition, the degree of mineralization is influenced by:
- geological region,
- waste water (especially in industrial regions),
- storm water runoff is predominantly in those cities where utilities use salt everywhere with icing.
To facilitate the gradation of mineralization ("salinity") of natural water, a table of categories from ultra-fresh to brines is used:
Taste and mineral supply to the body through water
The sensation threshold for sulfates is 500 mg / liter, and for chlorides it is 350 mg / liter. In general, water with a total salt content of 600 mg / liter is considered palatable.
Taste qualities of low-mineralized water are determined depending on the taste habits of consumers and are characterized in the range from "fresh and tasteless" to "light and pleasant".
At the same time, there is an objective lower limit of mineralization, based on the adaptive reactions of the body's homeostasis, which is at around 100 mg of dry residue per liter with indicators of 25 and 10 mg / l for calcium and magnesium, respectively. On the whole, the optimal value is considered to be in the range of 200-400 mg of dry residue per liter.
The possibility of supplying the body with minerals through water in the amount of a quarter of the required daily requirement is actively contested by opponents of this tendency. The evidence is compelling pivot tables that compare a number of features:
- Minerals necessary for a person (with a conditionally overestimated assumption of full digestibility of substances).
- The composition is subject to the content of the maximum permissible concentration.
- Daily water consumption, etc.
Taken together, these signs demonstrate that, in theory, water can be considered as a source of trace elements only to provide the body with fluorine and iodine. However, taking into account a number of conditional "ideal" assumptions and the difference in the content of such elements in different regions of Russia, drinking water cannot be considered as a sufficient source of even these microelements.
Mineral salts in industrial water
For a technical fluid for a number of industries, it becomes necessary to provide more stringent standards for salt content. Thus, the prevention of salt deposits in the steam-water ducts of a CHP or TPP can be ensured by the presence of salts in a minimum amount - less than 1 mg / liter - in both media (less than 1 mg / l).
When hydraulic flow moves through pipes, supersaturation with mineral salts, taking into account the low concentration and relatively low temperature, is usually not observed, however, in the boundary layers with a low flow rate, in the presence of roughness on the pipe walls, insulation defects, etc. precipitation can be triggered.
The tendencies towards strict regulation of the quality of technical water resources have two directions:
- creation of parameters for each indicator, in the same way as it is done for drinking resources;
- creation of water composition models for technical purposes, which would not divide the standard for individual physicochemical indicators, but would include a whole range of properties.
Now the requirements for the properties of the consumed and withdrawn hydraulic flow are recorded in the industry methodologies for the types of production and specific industries.
Removal of mineral salts
Demineralization (or the process of removing mineral substances) is carried out by means of deionization, distillation, electrolysis, reverse osmosis, which often requires a certain preparation of the resource, but allows achieving a very high (up to 99.9%) degree of purification, as is the case when using membrane systems.
- Distillation. The principle is based on evaporation and concentration of steam. The technology is considered to be energy-intensive and takes place with the formation of scale on the walls of the evaporator.
- Electrodialysis. The process occurs due to the movement of ions in an electric field with the installation of ion-selective membranes that allow only cations or only anions to pass through, as a result of which the concentration of salts in the volume limited by the membranes decreases.
- Deionization. Desalting provides ion exchange in 2 layers of ion exchange material. Deionized water is used in pharmaceuticals, chemistry, leather processing, and more.
- Reverse osmosis. Purification is based on "pushing" droplets through a semipermeable membrane with pores comparable in size to the H2O molecule. Under pressure, only the molecule itself, low-molecular gases, passes through the membrane, and impurities are filtered out and merged.
The water resource for this process requires preliminary cleaning from rust, sand and other suspensions, first with the help of mechanical cellular (up to 5 microns in size) cartridges, then - filters with granular carbon that adsorb metals, free chlorine, and then - filters with pressed coconut coal. to eliminate organochlorine compounds.
These filter membranes cannot be compared either in function or in scale with filter screens installed on aerators and water savers (for example, http://water-save.com/). In economists, filters are much larger and solve completely different problems of aerating water and creating the effect of a "full" stream with a lower actual water consumption.
The famous expression of nutritionists, "We are what we eat" can be paraphrased in relation to water. Our health directly depends on what we drink. Unfortunately, drinking water quality is a major concern around the world. The state of plumbing systems makes it increasingly necessary to resort to installing powerful filters or to the use of purchased bottled water. What kind of water do we call mineral water? How does water mineralization affect human health?
What kind of water can be called mineral?
Ordinary drinking water, which we collect from the tap, or buy in bottles, can also be considered, to some extent, mineral. It also contains salts and various chemical elements in different proportions. And yet, under a certain name, it is customary to mean water saturated with useful organic substances in varying degrees of concentration. The main indicator that determines the chemical composition of the main source of life, its suitability for drinking, is the total salinity of the water, or, in other words, the dry residue. It is an indicator of the amount of organic matter in one liter of liquid (mg / l).
Sources of mineralization
Mineralization of waters can occur both naturally, and industrially, artificially. In nature, underground rivers take in valuable salts, trace elements and other particles from the rocks along which they pass.
Alas, clean drinking springs have become a rarity. Mankind is increasingly forced to use special installations for cleaning them from contamination with harmful substances. Modern filtration methods can extract usable water from almost any liquid. As a result of the use of such technologies, it sometimes becomes almost distilled and also harmful for constant use in food. Artificially purified water undergoes re-mineralization and is filled with the necessary composition in an unnatural way.
Mineralization degree of water
Water with a dry matter value below 1000 mg / l is considered fresh, this is an indicator of most rivers and lakes. It is this threshold that is considered the highest for drinking water; at this limit, a person does not feel discomfort and an unpleasant salty or bitter taste. Mineralization of water above 1000 mg / l, in addition to changing its taste, reduces the ability to quench thirst, and sometimes has a harmful effect on the body.
Below 100 mg / l - a low degree of mineralization. Such water has an unpleasant taste and causes metabolic disturbances during prolonged use.
Scientists balneologists have deduced the optimal indicator of saturation with organic substances - from 300 to 500 mg / l. The dry residue from 500 to 100 mg / l is considered increased, but acceptable.
Consumer properties of water
According to its consumer properties, water should be divided into suitable for daily use, and that used for therapeutic and prophylactic purposes.
- Water purified artificially from all substances is suitable for drinking and cooking. It will not bring much harm, except that it will not bring absolutely any benefit. Those who, fearing infections, consume only such a liquid, risk getting a deficiency of useful salts and minerals. They will have to be replenished artificially.
- Table water is the most favorable for daily use, cleaned of dirt and harmful impurities and moderately nourished with everything you need.
- Medicinal table waters are already distinguished by the prefix “medicinally”. They are taken as a medicine or for prophylaxis. That is, everyone can drink them, but in moderation and not constantly, but they cannot be used for cooking.
- Purely medicinal mineral waters are usually taken only as prescribed by a doctor, in most cases as a procedure at a balneological resort. High mineralization of water makes its use unacceptable in a wide range.
Classification of water by composition
In the mineral society, it is customary to call medicinal and medicinal-table substances dissolved in them organic substances, minerals and gases is significantly different and depends on the location of the source. The main characteristic of water is its ionic composition, the general list of which includes about 50 different ions. The main mineralization of waters is represented by six main elements: cations of potassium, calcium, sodium and magnesium; anions of chloride, sulfate and bicarbonate. According to the predominance of certain elements, mineral waters are divided into three large main groups: hydrocarbonate, sulfate and chloride.
In most cases, in its pure form, a separate group of water is rarely present in nature. Most often, there are sources of a mixed type: chloride-sulfate, sulfate-hydrocarbonate, etc. In turn, the groups are divided into classes according to the predominance of certain ions. There are calcium, magnesium or mixed waters.
Just drink and be healthy
Mineralization of waters is widely used for medical purposes, both for internal use and for external use, in the form of baths and other water procedures.
- Hydrocarbonate waters are used to treat and prevent diseases of the digestive system associated with high acidity. They help get rid of heartburn, cleanse the body of sand and stones.
- Sulfates also stabilize bowel function. The main area of their influence is the liver, bile ducts. Recommend treatment with such waters for diabetes, obesity, hepatitis, biliary obstruction.
- The presence of chlorides eliminates disorders of the gastrointestinal tract, stabilizes the stomach and pancreas.
High mineralization can cause significant health damage if used incorrectly. A person with digestive and metabolic problems should take these natural medicines as directed and under the supervision of a healthcare professional.
It is a quantitative indicator of the content of substances dissolved in water. It is also called the solids content or total salt content, since the substances dissolved in water are in the form of salts. The most common inorganic salts (bicarbonates, chlorides and sulfates of calcium, magnesium, potassium and sodium) and a small amount of organic substances soluble in water. Total mineralization is confused with dry residue. In fact, these parameters are very close, but the methods for determining them are different. When determining the dry residue, more volatile organic compounds dissolved in water are not taken into account. As a result, the total salinity and dry matter may differ by the amount of these volatile compounds (usually no more than 10%). The level of salinity in drinking water is due to the quality of water in natural sources (which vary significantly in different geological regions due to the different solubility of minerals).
According to the general mineralization of water, they are divided into the following categories:
In addition to factors caused by nature, a person has a great influence on the general mineralization of water: industrial wastewater, city storm water (Salt is used in winter as an anti-icing agent), etc. According to the World Health Organization, there is no reliable information on the health effects of increased salt content. For medical reasons, WHO does not impose restrictions. As a rule, the taste of water is considered normal with a total mineralization of up to 600 mg / l, with a salt content of more than 1000-1200 mg / l, water can cause complaints from consumers. In this regard, WHO recommends a limit for total mineralization of 1000 mg / l for organoleptic indications. This level may vary depending on prevailing habits and local conditions. Today, in developed countries, people use water with low salt content - water purified by reverse osmosis technology. Such water is the purest and most harmless, it is widely used in the food industry, the manufacture of bottled water, etc. Read more about minerals and water in the article: Water and minerals. A separate topic is the value of mineralization during the deposition of scale and precipitation in the boiler room, boiler and sanitary equipment. In this case, special requirements apply to the water, and the lower the level of mineralization (especially the content of hardness salts), the better.
Rigidity
The property of water, determined by the presence of calcium and magnesium salts in dissolved form.
Water hardness chemistry
It is accepted that water hardness is usually associated with calcium cations (Ca2 +) and, to a lesser extent, magnesium (Mg2 +). In fact, all divalent cations affect water hardness. Sediment and scale (hardness salts) are formed as a result of the interaction of divalent cations with anions. Sodium Na + - a monovalent cation does not interact with anions.
Here are the main metal cation exchangers with which they are associated and cause rigidity.
Iron, manganese and strontium have little effect on hardness compared to calcium and magnesium. The solubility of aluminum and ferric iron is small at the pH level of natural water, so their effect on water hardness is also small.
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