Reverse osmosis. Possible malfunctions of reverse osmosis systems Weak water pressure from the system tap

Typical cases of malfunctioning systems reverse osmosis Atoll and methods for their elimination. If you do not find the answer and solution to the problem in this collection, then see instruction manual for your model or contact service center "Rusfilter-Service" .

Drainage water is constantly flowing

Cause

• Shut-off valve defective
• Replaceable elements clogged, prefilters damaged
• Low pressure

elimination

For this:

1. Close the tap on the storage tank;
2. Open a clean water faucet;
3. You will hear water pouring out of drainage tube;
4. Close the clean water tap;
5. After a few minutes, the flow of water from the drain tube should stop;
6. If flow does not stop, replace shutoff valve.

• Replace cartridges, including if necessary membrane or damaged pre-filters
• A system without a pump requires an inlet pressure of at least 2.8 atm. If the pressure is lower than specified, then a booster pump should be installed (see the “Options” section in the instruction manual)

leaks

Cause

• The edges of the connecting tubes are not cut at 90°, or the edge of the tube has "burrs".
• Tubes not tightly connected
• Threaded connections not tightened
• Missing o-rings
• Pressure surges in the inlet pipeline above 6 atm

elimination

• When installing, dismantling or changing filter elements, make sure that the edges of the connecting tubes are even (cut at a right angle) and without roughness and thinning.
• Insert the tube into the connector until it stops and apply additional force to seal the connection. Pull tubing to check connections.
• Tighten screw connections if necessary.
• Contact supplier
• To prevent leaks, it is recommended to install a Honeywell D04 or D06 pressure reducing valve in the system before the first prefilter, as well as atoll Z-LV-FPV0101

Water does not flow from the tap or drips, i.e. low performance

Cause

• Low water pressure at filter inlet
• The tubes are bent
• Low temperature water

elimination

• A system without a pump requires an inlet pressure of at least 2.8 atm. If the pressure is lower than specified, then a booster pump should be installed (see the "Options" section in the operating instructions for the specific model)
• Check tubing and remove kinks
• Working temperature cold water = 4-40°С

There is not enough water in the tank

Cause

• The system has just started
• Clogged prefilters or membrane
• Air pressure in the tank is high
• Clogged check valve in the membrane flask

elimination

• Replace prefilters or membrane
• Replace flow restrictor

milky water

Cause

• Air in the system

elimination

• Air in the system is the norm in the early days of the system. In one to two weeks it will be completely withdrawn.

Water has bad smell or smack

Cause

• The resource of the carbon post-filter has run out
• Membrane clogged
• The preservative is not washed out of the tank
• Incorrect tubing connection

elimination

• Replace carbon post-filter
• Replace membrane
• Empty the tank and fill again (the procedure may be repeated several times)
• Check the connection order (see the connection diagram in the instructions for this filter)

Water is not supplied from the tank to the faucet

Cause

• The pressure in the tank is below the allowable
• Tank diaphragm rupture
• Tank valve closed

elimination

• Pump air through the air valve of the tank to the required pressure (0.5 atm.) With a car or bicycle pump
• Replace tank
• Open the faucet on the tank

Water does not enter the drain

Cause

• Clogged water flow restrictor to drain

elimination

• Replace flow restrictor

increased noise

Cause

• Clogged drain
• High inlet pressure

elimination

• Find and remove blockage
• Install the pressure reducing valve. Adjust the pressure with the water tap

The pump does not turn off

Cause

• There is not enough water in the tank.
• Sensor adjustment required high pressure.

elimination

• The tank is filled within 1.5-2 hours. Low temperature and inlet pressure reduce the performance of the membrane. Might just have to wait
• Replace prefilters or membrane
• Check the pressure in the empty storage tank through the air valve using a pressure gauge. normal pressure 0.4-0.5 atm. In case of insufficient pressure, pump up with a car or bicycle pump.
• Replace flow restrictor
• The check valve is mounted on the membrane bulb inside the central connector located on the side opposite the bulb cap. Unscrew the connector, rinse the valve under running water.

If water does not enter the drain and the pump does not turn off, turn the adjusting hex on the high pressure sensor counterclockwise.

We express our gratitude for the help in preparing this material, Ph.D. Barasyev Sergey Vladimirovich, academician of the Belarusian Engineering Academy.

What are these impurities and where do they come from in water?

Where do harmful impurities come from?

Water, as you know, is not only the most common substance in nature, but also a universal solvent. More than 2,000 natural substances and elements have been found in water, of which only 750 have been identified, mainly organic compounds. However, water contains not only natural substances, but also toxic man-made substances. They enter water basins as a result of industrial emissions, agricultural runoff, and household waste. Every year, thousands of chemicals enter water sources with unpredictable effects on environment, hundreds of which are new chemical compounds. Elevated concentrations of toxic heavy metal ions (for example, cadmium, mercury, lead, chromium), pesticides, nitrates and phosphates, petroleum products, and surfactants can be found in water. Every year, up to 12 million tons of water enters the seas and oceans. tons of oil.

A certain contribution to the increase in the concentration of heavy metals in water is also made by acid rain in industrialized countries. Such rains can dissolve minerals in the soil and increase the content of toxic heavy metal ions in the water. Radioactive waste from nuclear power plants is also involved in the water cycle in nature. The discharge of untreated wastewater into water sources leads to microbiological contamination of water. According to the World Health Organization, 80% of diseases in the world are caused by poor quality and unsanitary conditions of water. The problem of water quality is especially acute in rural areas - approximately 90% of all rural residents in the world constantly use polluted water for drinking and bathing.

Are there standards for drinking water?

Don't drinking water standards protect the public?

Regulatory recommendations are formed as a result of expert judgment based on several factors - analysis of data on the prevalence and concentration of substances commonly found in drinking water; the possibilities of purification from these substances; scientifically substantiated conclusions about the impact of pollutants on a living organism. As for the last factor, it has some uncertainty, since experimental data are transferred from small animals to humans, then linearly (and this is a conditional assumption) extrapolated from large doses of harmful substances to small ones, then a "reserve factor" is introduced - the result obtained by the concentration of harmful substances are usually divisible by 100.

In addition, there is uncertainty associated with the uncontrolled release of technogenic impurities into the water and the lack of data on the entry of additional amounts of harmful substances from the air and food. Regarding the influence of carcinogenic and mutagenic substances, most scientists consider their effect on the body to be non-threshold, that is, it is enough for one molecule of such a substance to get to the corresponding receptor to cause a disease. The actual recommended values ​​for such substances allow for one case of disease due to water per 100,000 population. Further, the regulations for drinking water provide a very limited list of substances subject to control and do not take into account viral infection at all. And, finally, the peculiarities of the organism of various people are not taken into account at all (which is fundamentally impossible). Thus, the standards for drinking water reflect, in essence, the economic capabilities of states

If drinking water meets accepted standards, why should it be further purified?

For several reasons. Firstly, the formation of standards for drinking water is based on an expert assessment based on several factors that often do not take into account man-made water pollution and have some uncertainty in substantiating conclusions about the concentrations of pollutants that affect a living organism. As a result, the recommendations of the World Health Organization allow, for example, one cancer per hundred thousand of the population due to water. Therefore, WHO experts already on the first pages of the “Guidelines for drinking water quality control” (Geneva, WHO) state that “despite the fact that the recommended values ​​provide for a quality of water acceptable for consumption throughout life, this does not mean that the quality of drinking water can be reduced to the recommended level. In reality, ongoing efforts are needed to keep the quality of drinking water at the highest possible level…and the level of exposure to toxic substances should be as low as possible.” Secondly, the possibilities of states in this regard (the cost of purification, distribution and monitoring of water) are limited, and common sense suggests that it is unreasonable to bring to perfection all the water supplied to houses for household and drinking needs, especially since approximately one percent of all water used. Thirdly, it happens that efforts to purify water at wastewater treatment plants are neutralized due to technical violations, accidents, recharge of polluted waters, secondary pipe pollution. So the principle of "protect yourself" is very relevant.

How to deal with the presence of chlorine in water?

If water chlorination is dangerous, why is it used?

Chlorine performs a useful guardian function against bacteria and has a prolonged action, but it also plays a negative role - in the presence of certain organic substances, it forms carcinogenic and mutagenic organochlorine compounds. It is important to choose the lesser evil here. In critical situations and in case of technical failures, chlorine overdoses (hyperchlorination) are possible, and then chlorine, as a toxic substance, and its compounds become dangerous. In the United States, studies have been conducted on the effect of chlorinated drinking water on birth defects. It was found that high levels of carbon tetrachloride caused low weight, fetal death or defects in the central nervous system, and benzene and 1,2-dichloroethane caused heart defects.

On the other hand, this fact is interesting and indicative - the construction of chlorine-free (based on combined chlorine) treatment systems in Japan has led to a threefold reduction in medical costs, and to an increase in life expectancy by ten years. Since it is not possible to completely abandon the use of chlorine, the way out is seen in the use of combined chlorine (hypochlorites, dioxides), which makes it possible to reduce harmful by-product chlorine compounds by an order of magnitude. Considering also the low efficiency of chlorine against viral infection of water, it is advisable to use ultraviolet disinfection of water (of course, where it is economically and technically justified, since ultraviolet does not have a prolonged effect).

In everyday life, charcoal filters can be used to remove chlorine and its compounds.

How serious is the problem of heavy metals in drinking water?

As for heavy metals (HMs), most of them have high biological activity. In the process of water treatment, new impurities may appear in the treated water (for example, toxic aluminum may appear during the coagulation stage). The authors of the monograph "Heavy metals in the environment" note that "according to forecasts and estimates in the future, they (heavy metals) may become more dangerous pollutants than waste from nuclear power plants and organic substances." "Metal pressure" can become a serious problem due to the total influence of heavy metals on the human body. Chronic HM intoxications have a pronounced neurotoxic effect, and also significantly affect the endocrine system, blood, heart, blood vessels, kidneys, liver, and metabolic processes. They also affect the reproductive function of a person. Some metals have an allergenic effect (chromium, nickel, cobalt), can lead to mutagenic and carcinogenic effects (chromium, nickel, iron compounds). Facilitates the situation so far, in most cases, a low concentration of heavy metals in groundwater. The presence of heavy metals in water from surface sources is more likely, as well as their appearance in water as a result of secondary pollution. Most effective method HM removal - the use of filter systems based on reverse osmosis.

Since ancient times, it was believed that water after contact with silver objects becomes safe to drink and even useful.

Why is water silvering not used everywhere today?

The use of silver as a disinfecting agent has not been widely adopted for a number of reasons. First of all, according to SanPiN 10-124 RB99, based on WHO recommendations, silver as a heavy metal, along with lead, cadmium, cobalt and arsenic, belongs to hazard class 2 (highly hazardous substance), causing long-term use argyrosis disease. According to WHO, the natural total consumption of silver with water and food is about 7 µg/day, the maximum allowable concentration in drinking water is 50 µg/l, the bacteriostatic effect (suppression of the growth and reproduction of bacteria) is achieved at a concentration of silver ions of about 100 µg/l, and bactericidal (destruction of bacteria) - over 150 mcg / l. At the same time, there is no reliable data on the function of silver, which is vital for the human body. Moreover, silver is not effective enough against spore-forming microorganisms, viruses and protozoa and requires prolonged contact with water. Therefore, WHO experts consider, for example, that the use of filters based on activated carbon impregnated with silver "is only allowed for drinking water that is known to be microbiologically safe."

Most often, water silvering is used in cases of long-term storage of disinfected drinking water in sealed containers without access to light (in some airlines, on ships, etc.), and for disinfecting water in pools (in combination with copper), allowing to reduce the degree chlorination (but not completely abandon it).

Is it true that drinking water softened by water purification filters is unhealthy?

The hardness of water is mainly due to the presence of dissolved calcium and magnesium salts in it. The bicarbonates of these metals are unstable and over time are converted into water-insoluble carbonate compounds that precipitate. This process is accelerated when heated, forming a hard white coating on the surfaces of heating devices (well-known scale in teapots), and boiled water becomes softer. At the same time, calcium and magnesium are removed from the water - elements necessary for the human body.

On the other hand, a person receives various substances and elements with food, and with food to a greater extent. The human body's need for calcium is 0.8–1.0 g, for magnesium – 0.35–0.5 g per day, and the content of these elements in water of medium hardness is 0.06–0.08 g and 0.036–0.048 d, respectively, i.e. about 8-10 percent of the daily requirement and less for softer or boiled water. At the same time, hardness salts cause high turbidity and sore throat from tea, coffee and other drinks due to the content of sediment floating on the surface and in the volume of the drink, making it difficult to cook food.

Thus, the question is to prioritize - which is better: to drink water from the tap or qualitatively purified after the filter (especially since some filters have little effect on the initial concentration of calcium and magnesium).

From the point of view of sanitary doctors, water should be safe for consumption, tasty and stable. Since domestic water purification filters practically do not change the water stability index, they have the ability to connect mineralizers and UV water disinfection devices, they provide clean and tasty cold and softened (by 50/90%) water for cooking and hot drinks.

What does magnetic water treatment give?

Water is an amazing substance in nature, changing its properties not only depending on the chemical composition, but also under the influence of various physical factors. In particular, it was experimentally found that even a short-term exposure to a magnetic field increases the rate of crystallization of substances dissolved in it, coagulation of impurities and their precipitation.

The essence of these phenomena has not been fully elucidated, and in the theoretical description of the processes of the influence of a magnetic field on water and impurities dissolved in it, there are mainly three groups of hypotheses (according to Klassen): colloidal particles in water, the remains of which form centers of crystallization of impurities, accelerating their precipitation; - "ionic", according to which the influence of a magnetic field leads to an increase in the hydration shells of impurity ions, which hinder the approach of ions and their conglomeration; - "water", whose supporters believe that the magnetic field causes deformation of the structure of water molecules associated with the help of hydrogen bonds, thus affecting the rate of physical and chemical processes occurring in water. Be that as it may, the treatment of water with a magnetic field has found wide practical application.

It is used to suppress scale formation in boilers, in oil fields to eliminate the deposition of mineral salts in pipelines and paraffins in oil pipelines, to reduce the turbidity of natural water at waterworks and wastewater treatment as a result of the rapid deposition of fine contaminants. In agriculture, magnetic water significantly increases the yield, in medicine it is used to remove kidney stones.

What methods of water disinfection are currently used in practice?

All known technological methods of water disinfection can be divided into two groups - physical and chemical. The first group includes such disinfection methods as cavitation, transmission of electric current, radiation (gamma quanta or x-rays) and ultraviolet (UV) irradiation of water. The second group of disinfection methods is based on the treatment of water with chemicals (for example, hydrogen peroxide, potassium permanganate, silver and copper ions, bromine, iodine, chlorine, ozone), which at certain doses have a bactericidal effect. Due to a number of circumstances (insufficiency of practical developments, high cost of implementation and (or) operation, side effects, selectivity of the effect of the active agent), chlorination, ozonation and UV irradiation are mainly used in practice. When choosing a specific technology, hygienic, operational, technical and economic aspects are taken into account.

In general, if we talk about the shortcomings of this or that method, it can be noted that: - chlorination is the least effective against viruses, causes the formation of carcinogenic and mutagenic organochlorine compounds, special measures are required for equipment materials and working conditions for maintenance personnel, there is a danger of overdose, there is a dependence on temperature, pH and chemical composition of water; - ozonation is characterized by the formation of toxic by-products (bromates, aldehydes, ketones, phenols, etc.), the danger of overdose, the possibility of re-growth of bacteria, the need to remove residual ozone, a complex set of equipment (including high-voltage equipment), the use of stainless materials, high construction and operating costs ; - the use of UV irradiation requires high-quality preliminary water treatment, there is no effect of prolonging the disinfecting action.

What are the characteristics of UV water disinfection plants?

In recent years, practical interest in the method of UV irradiation for the purpose of disinfecting drinking and waste water has increased significantly. This is due to a number of undoubted advantages of the method, such as the high efficiency of inactivation of bacteria and viruses, the simplicity of technology, the absence of side effects and influence on the chemical composition of water, and low operating costs. Development and application as emitters of mercury lamps low pressure made it possible to increase the efficiency up to 40% compared to high-pressure lamps (efficiency 8%), reduce the unit radiation power by an order of magnitude, while simultaneously increasing the service life of UV emitters by several times and preventing any significant formation of ozone.

An important parameter of the installation of UV radiation is the dose of radiation and the coefficient of absorption of UV radiation by water, which is inextricably linked with it. The radiation dose is the energy density of UV radiation in mJ/cm2 received by the water during its flow through the installation. The absorption coefficient takes into account the attenuation of UV radiation when passing through the water column due to the effects of absorption and scattering and is defined as the ratio of the fraction of the absorbed radiation flux when passing through a 1 cm thick layer of water to its initial value in percent.

The value of the absorption coefficient depends on the turbidity, color of the water, the content of iron, manganese in it, and for water that meets the accepted standards, it is in the range of 5 - 30% / cm. The choice of UV irradiation installation should take into account the type of bacteria, spores, viruses to be inactivated, since their resistance to irradiation varies greatly. For example, inactivation (with an efficiency of 99.9%) of bacteria of the Escherichia coli group requires 7 mJ/cm2, poliomyelitis virus - 21, nematode eggs - 92, Vibrio cholerae - 9. In world practice, the minimum effective dose of radiation varies from 16 to 40 mJ /cm2.

Is copper and galvanized plumbing harmful to health?

According to SanPiN 10-124 RB 99, copper and zinc are classified as heavy metals with hazard class 3 - dangerous. On the other hand, copper and zinc are essential for the metabolism of the human body and are considered non-toxic at concentrations commonly found in water. It is obvious that both excess and deficiency of microelements (and copper and zinc also belong to them) can cause various disturbances in the activity of human organs.

Copper is included integral part in a number of enzymes that utilize proteins, carbohydrates, increases the activity of insulin, and is simply necessary for the synthesis of hemoglobin. Zinc is part of a number of enzymes that provide redox processes and respiration, and is also necessary for the production of insulin. The accumulation of copper occurs mainly in the liver and partly in the kidneys. Exceeding its natural content in these organs by about two orders of magnitude leads to necrosis of liver cells and kidney tubules.

Lack of copper in the diet can cause birth defects. The daily dose for an adult is at least 2 mg. Lack of zinc leads to a decrease in the function of the gonads and the pituitary gland of the brain, to a slowdown in the growth of children and anemia, and a decrease in immunity. The daily dose of zinc is 10-15 mg. An excess of zinc causes mutagenic changes in the cells of organ tissues and damages cell membranes. Copper in its pure form practically does not interact with water, but in practice its concentration increases slightly in water supply networks from copper pipes(similarly, the concentration of zinc in a galvanized water pipe increases).

The presence of copper in the water supply system is not considered hazardous to health, but can adversely affect the use of water for domestic purposes - increase the corrosion of galvanized and steel fittings, impart color to water and a bitter taste (in concentrations above 5 mg / l), cause staining of fabrics (in concentrations above 1 mg/l). It is from the household point of view that the MPC value of copper is set equal to 1.0 mg/l. For zinc, the MPC value in drinking water of 5.0 mg/l was determined from an aesthetic point of view, taking into account taste perceptions, since at higher concentrations the water has an astringent taste and may opalescent.

Is it harmful to drink mineral water with a high fluoride content?

Recently, a lot of mineral water with a high fluoride content has appeared on the market.

Isn't it bad to drink it all the time?

Fluorine is a substance with a sanitary and toxicological hazard index of hazard class 2. This element is naturally found in water in various, usually low concentrations, as well as in a number of food products (for example, in rice, tea) also in small concentrations. Fluorine is one of the essential trace elements for the human body, as it participates in biochemical processes that affect the entire body. As part of the bones, teeth, nails, fluorine has a beneficial effect on their structure. It is known that the lack of fluorine leads to dental caries, which affects more than half of the world's population.

Unlike heavy metals, fluoride is efficiently excreted from the body, so it is important to have a source of regular renewal. The content of fluorine in drinking water less than 0.3 mg/l suggests its deficiency. However, already at concentrations of 1.5 mg/l, there are cases of mottled teeth; at 3.0–6.0 mg/l, skeletal fluorosis may occur, and at concentrations above 10 mg/l, disabling fluorosis may develop. Based on these data, the WHO recommended level of fluoride in drinking water is 1.5 mg/l. For countries with a hot climate or for greater consumption of drinking water, this level is reduced to 1.2 and even to 0.7 mg/l. Thus, fluorine is hygienically useful in a narrow concentration range of about 1.0 to 1.5 mg/L.

Since fluoridation of drinking water from centralized water supply is impractical, manufacturers of bottled water resort to the most rational improvement of its quality by artificial fluoridation within hygienically acceptable limits. The content of fluorine in bottled water at a concentration above 1.5 mg / l should indicate its natural origin, but such water can be classified as medicinal and is not intended for permanent use.

Side effects of chlorination. Why is no alternative offered?

Recently, in scientific and practical circles in the field of water treatment at conferences, symposiums, the issue of the effectiveness of one or another method of water disinfection has been actively discussed. There are three most common methods of water inactivation - chlorination, ozonation and ultraviolet (UV) irradiation. Each of these methods has certain disadvantages that do not allow completely abandoning other methods of water disinfection in favor of any chosen one. From the technical, operational, economic and medical points of view, the UV irradiation method could be the most preferable, if it were not for the lack of a prolonged disinfecting effect. On the other hand, the improvement of the chlorination method based on combined chlorine (in the form of dioxide, sodium or calcium hypochlorite) can significantly reduce one of the negative side effects of chlorination, namely, to reduce the concentration of carcinogenic and mutagenic organochlorine compounds by five to ten times.

However, the problem of viral contamination of water remains unresolved - the effectiveness of chlorine against viruses is known to be low, and even hyperchlorination (with all its disadvantages) is not able to cope with the task of complete disinfection of the treated water, especially at a high concentration of organic impurities in the treated water. water. The conclusion suggests itself - to use the principle of combination of methods, when the methods complement each other, in a complex solving the problem. In the case under consideration, the consistent application of UV irradiation methods and the dosed introduction of bound chlorine into the treated water most effectively meet the main purpose of the disinfection system - the complete inactivation of the object of disinfection treatment with a prolonged aftereffect. An additional bonus in tandem UV-bound chlorine is the ability to reduce UV exposure and chlorination doses compared to those used when using the above methods separately, which provides an additional economic benefit. The proposed combination of disinfection methods is not the only one possible today, and work in this direction is encouraging.

How dangerous is it to drink water with an unpleasant taste, smell and cloudy appearance?

Sometimes tap water has an unpleasant taste, smell and is cloudy in appearance. How dangerous is it to drink such water?

According to the accepted terminology, the properties of water named above refer to organoleptic indicators and include smell, taste, color and turbidity of water. The smell of water is mainly associated with the presence of organic substances (natural or industrial origin), chlorine and organochlorine compounds, hydrogen sulfide, ammonia, or the activity of bacteria (not necessarily pathogenic). Causes an unpleasant aftertaste the largest number consumer complaints. Substances that affect this indicator include magnesium, calcium, sodium, copper, iron, zinc, bicarbonates (for example, water hardness), chlorides and sulfates. The color of the water is due to the presence of colored organic matter, such as humic substances, algae, iron, manganese, copper, aluminum (combined with iron), or colored industrial pollutants. Turbidity is caused by the presence of finely dispersed suspended particles (clay, silt components, colloidal iron, etc.) in the water.

Turbidity leads to a decrease in the effectiveness of disinfection and stimulates the growth of bacteria. Although substances that affect aesthetic and organoleptic characteristics are rarely present at toxic concentrations, the cause of the discomfort should be determined (more often, substances that are not detectable by the human senses are dangerous) and the concentration of substances that cause discomfort should be kept well below the threshold level. As an acceptable concentration of substances that affect aesthetic and organoleptic characteristics, a concentration of 10 (for organic substances) or more times lower than the threshold is taken.

According to WHO experts, about 5% of people can taste or smell certain substances at concentrations 100 times lower than the threshold. However, excessive efforts to completely eliminate substances that affect organoleptic characteristics at the scale of human settlements may be prohibitively expensive and even impossible. In this situation, it is advisable to use properly selected filters and systems for post-treatment of drinking water.

What is the harmfulness of nitrates and how to get rid of them in drinking water?

Nitrogen compounds are present in water, mainly from surface sources, in the form of nitrates and nitrites and are classified as substances with a sanitary-toxicological indicator of harmfulness. According to SanPiN 10-124 RB99 MPC for NO3 nitrates is 45 mg/l (hazard class 3), and for NO2 nitrites – 3 mg/l (hazard class 2). Excess levels of these substances in water can cause oxygen starvation due to the formation of methemoglobin (a form of hemoglobin in which heme iron is oxidized to Fe (III), which is not able to carry oxygen), as well as some forms of cancer. Infants and newborns are most susceptible to methemoglobinemia. The issue of purification of drinking water from nitrates is most acute for rural residents, since the widespread use of nitrate fertilizers leads to their accumulation in the soil, and then, as a result, in rivers, lakes, wells and shallow wells. To date, there are two methods to remove nitrates and nitrites from drinking water - based on reverse osmosis and based on ion exchange. Unfortunately, the sorption method (using activated carbons) as the most accessible one is characterized by low efficiency.

The reverse osmosis method has an extremely high efficiency, but its high cost and total water desalination should be taken into account. To prepare drinking water for small quantities nevertheless, it should be considered the most suitable way to purify water from nitrates, especially since it is possible to connect an additional stage with a mineralizer. The ion exchange method is implemented in practice in installations with a strongly basic anion exchange resin in the Cl-form. The process of removing dissolved nitrogen compounds consists in replacing Cl- ions on the anion-exchange resin with NO3- ions from water. However, SO4-, HCO3-, Cl- anions also participate in the exchange reaction, and sulfate anions are more efficient than nitrate anions, and the capacity for nitrate ions is low. When implementing this method, one should additionally take into account the limitation of the total concentration of sulfates, chlorides, nitrates and bicarbonates by the MPC value for chloride ions. To overcome these shortcomings, special selective anion exchange resins have been developed and are offered, the affinity of which with respect to nitrate ions is the highest.

Are radionuclides present in drinking water and how seriously should they be taken?

Radionuclides can end up in the source of water used by humans due to the natural presence of radionuclides in the earth's crust, as well as due to man-made human activities - during nuclear weapons testing, insufficient wastewater treatment of nuclear energy and industry enterprises or accidents at these enterprises, loss or theft of radioactive materials, extraction and processing of oil, gas, ores, etc. Taking into account the reality of this kind of water pollution, requirements for its radiation safety are introduced into the standards for drinking water, namely, the total α-radioactivity (flux of helium nuclei) should not exceed 0.1 Bq / l, and the total? -radioactivity (electron flux) is not higher than 1.0 Bq / l (1 Bq corresponds to one decay per second). The main contribution to human radiation exposure today is made by natural radiation - up to 65-70%, ionizing sources in medicine - more than 30%, the rest of the radiation dose falls on man-made sources of radioactivity - up to 1.5% (according to A.G. Zelenkov). In turn, a significant share in the background of natural external radiation falls on? -radioactive radon Rn-222. Radon is an inert radioactive gas, 7.5 times heavier than air, colorless, tasteless and odorless, contained in the earth's crust and highly soluble in water. Radon enters the human environment from building materials, in the form of gas leaking from the bowels of the earth to its surface, during the combustion of natural gas, as well as with water (especially if it is supplied from artesian wells).

In the case of insufficient air exchange in houses and individual rooms in a house (usually in basements and lower floors), the dispersion of radon in the atmosphere is difficult and its concentration can exceed the maximum allowable by tens of times. For example, in cottages with their own well water supply, radon can be released from the water when using the shower or kitchen faucet, and its concentration in the kitchen or bathroom can be 30-40 times higher than the concentration in residential premises. The greatest harm from exposure is caused by radionuclides that enter the human body by inhalation, as well as with water (at least 5% of the total dose of radon radiation). With prolonged intake of radon and its products into the human body, the risk of lung cancer increases many times over, and in terms of the likelihood of this disease, radon is in second place in the series of causality after smoking (according to the US Public Health Service). In this situation, water settling, aeration, boiling, or the use of carbon filters (>99% efficiency), as well as ion exchange resin softeners, can be recommended.

Recently, more and more people talk about the benefits of selenium and even produce drinking water with selenium; at the same time, selenium is known to be poisonous. I would like to know how to determine the rate of its consumption?

Indeed, selenium and all its compounds are toxic to humans above certain concentrations. According to SanPiN 10-124 RB99, selenium is classified as a substance with a sanitary and toxicological hazard rating of hazard class 2. At the same time, selenium plays a key role in the activity of the human body. This is a biologically active microelement, which is part of most (more than 30) hormones and enzymes and provides normal functioning organism and its protective and reproductive functions. Selenium is the only trace element whose incorporation into enzymes is encoded in DNA. The biological role of selenium is associated with its antioxidant properties (along with vitamins A, C and E), due to the participation of selenium in the construction, in particular, of one of the most important antioxidant enzymes - glutathione peroxidase (from 30 to 60% of all selenium in the body).

Selenium deficiency (below the average daily requirement of the human body 160 mcg) leads to a decrease in the protective function of the body from free radical oxidants that irreversibly damage cell membranes and, as a result, to diseases (heart, lung, thyroid, etc.), weakening of the immune system, premature aging and reduced life expectancy. Given all of the above, you should adhere to the optimal amount of selenium intake in total with food (mostly) and water. The WHO recommended maximum daily intake of selenium with drinking water should not exceed 10% of the recommended maximum daily dietary intake of 200 micrograms of selenium. Thus, when consuming 2 liters of drinking water per day, the selenium concentration should not exceed 10 µg/l, and this value is taken as MPC. In fact, the territories of many countries are classified as selenium-deficient (Canada, USA, Australia, Germany, France, China, Finland, Russia, etc.), and intensive farming, soil erosion and acid rain aggravate the situation, reducing the content of selenium in the soil. As a result, people consume less and less of this essential element with natural protein and plant foods, and there is an increasing need for nutritional supplements or special bottled water (especially after 45-50 years). In conclusion, we can note the leaders in the content of selenium among products: coconut (0.81 mcg), pistachios (0.45 mcg), lard(0.2-0.4 mcg), garlic (0.2-0.4 mcg), sea ​​fish(0.02-0.2mcg), wheat bran (0.11mcg), porcini mushrooms (0.1mcg), eggs (0.07-0.1mcg).

There is a cheap "folk" way to improve the quality of water by insisting it on flint. Is this method really that effective?

First, the terminology needs to be clarified. Flint is a mineral formation based on silicon oxide, consisting of quartz and chalcedony with coloring metal impurities. For medicinal purposes, apparently, a variety of silica is promoted - diatomite, of organogenic origin. Silicon is a chemical element that occupies the second place in nature after oxygen in terms of prevalence (29.5%) and forms in nature its main minerals - silica and silicates. The main source of silicon compounds in natural waters are the processes of chemical dissolution of silicon-containing minerals, the entry of dying plants and microorganisms into natural waters, as well as the entry of sewage enterprises using silicon-containing substances in production. In slightly alkaline and neutral waters, it is present, as a rule, in the form of undissociated silicic acid. Due to low solubility, its average content in groundwater is 10 - 30 mg/l, in surface water - from 1 to 20 mg/l. Only in highly alkaline waters does silicic acid migrate in ionic form, and therefore its concentration in alkaline waters can reach hundreds of mg/l. If we do not touch on the assurances of some ardent supporters of this method of post-treatment of drinking water about giving water in contact with flint some supernatural healing properties, then the question boils down to clarifying the fact that “harmful” impurities are sorbed by flint and the release of “useful” impurities in dynamic equilibrium with the water surrounding the flint . Such studies were actually carried out and, moreover, scientific conferences were devoted to this issue.

In general, if we ignore the discrepancies in the results of studies by different authors associated with differences in samples (after all, one must take into account the irreproducibility of the properties of natural minerals) and experimental conditions, the sorption qualities of flint with respect to radionuclides and heavy metal ions, the binding of mycobacteria on silicon colloids ( for example, according to M.G. Voronkov, Irkutsk Institute of Organic Chemistry), as well as the fact that silicon is released into the contact water in the form of silicic acids. As for the latter, this fact attracted researchers to a closer study of the role of silicon as a trace element in the activity of human organs, since there was an opinion about the biological uselessness of silicon compounds. It turned out that silicon stimulates the growth of hair and nails, is part of collagen fibers, neutralizes toxic aluminum, plays an important role in the healing of bones in fractures, is necessary to maintain the elasticity of arteries and plays an important role in the prevention of atherosclerosis. At the same time, it is known that with regard to microelements (unlike macroelements), tiny deviations from biologically justified consumption doses are acceptable and one should not get involved in the constant excessive consumption of silicon from drinking water in concentrations above the maximum allowable - 10 mg / l.

Is oxygen needed in drinking water?

The effect of oxygen dissolved in water in the form of O2 molecules is reduced mainly to the effect on redox reactions involving metal cations (for example, iron, copper, manganese), nitrogen- and sulfur-containing anions, and organic compounds. Therefore, when determining the stability of water and its organoleptic qualities, along with measuring the concentration of organic and inorganic substances, pH, it is important to know the concentration of oxygen (in mg / l) in this water. Water from underground sources, as a rule, is extremely depleted in oxygen, and the absorption of atmospheric oxygen during its extraction and transportation in water distribution networks is accompanied by a violation of the initial anion-cation balance, leading, for example, to precipitation of iron, a change in the pH of water, and the formation of complex ions. Producers of mineral and drinking bottled water, extracted from great depths, often have to deal with such phenomena. In surface water, the oxygen content varies greatly depending on the concentration of various organic and inorganic substances, as well as the presence of microorganisms. The balance of oxygen is determined by the balance of the processes leading to the entry of oxygen into the water and its consumption. The increase in the oxygen content in water is facilitated by the processes of oxygen absorption from the atmosphere, the release of oxygen by aquatic vegetation during photosynthesis, the replenishment of surface sources with oxygenated rain and water. melt waters. The rate of this process increases with a decrease in temperature, with an increase in pressure and a decrease in salinity. In underground sources, low oxygen content can be caused by vertical thermal convection. The processes of chemical oxidation of substances (nitrites, methane, ammonium, humic substances, organic and inorganic wastes in anthropogenic wastewater), biological (respiration of organisms) and biochemical consumption (respiration of bacteria, oxygen consumption during the decomposition of organic substances).

The rate of oxygen consumption increases with increasing temperature and bacterial counts. The quantitative characteristic of chemical oxygen consumption is based on the concept of oxidizability - the amount of oxygen in mg consumed for the oxidation of organic and inorganic substances contained in 1 liter of water (the so-called permanganate oxidizability for slightly polluted waters, and bichromate oxidizability (or COD - chemical oxygen demand). Biochemical oxygen demand (BOD, mg / l) is considered as a measure of water pollution and is defined as the difference in the oxygen content in water before and after keeping it in the dark for 5 days at 20 ° C. Water with a BOD not higher than 30 mg / l is considered practically pure. Although WHO experts do not quantify oxygen in drinking water, they nevertheless recommend “… keeping dissolved oxygen concentrations as close to saturation as possible, which in turn requires that concentrations of biologically oxidizable substances… be as low as possible.” oxygenated point of view water exhibits corrosive properties to metal and concrete, which is undesirable. The degree of saturation (relative oxygen content as a percentage of its equilibrium content) is considered to be a compromise of 75% (or the equivalent of 7 in summer to 11 in winter mg O2/l).

In drinking water, the pH according to sanitary standards should be from 6 to 9, and in some soft drinks it can be 3-4. What is the role of this indicator and is it harmful to drink drinks with such a low pH value?

In the WHO recommendations, the value of the pH index is in an even narrower range of 6.5-8.5, but this is due to certain considerations. The hydrogen index is a value that characterizes the concentration of hydrogen ions H+ (hydroxonium H3O+) in water or in aqueous solutions. Since this value, expressed in g-ions per liter of aqueous solution, is extremely small, it is customary to define it as the negative decimal logarithm of the concentration of hydrogen ions and denote it with the symbol pH. In pure water (or neutral solution) at 250C, the pH is 7 and reflects the equality of H+ and OH- ions (hydroxyl group) as constituents of the water molecule. In aqueous solutions, depending on the H + / OH- ratio, the pH value can vary from 1 to 14. At a pH value of less than 7, the concentration of hydrogen ions exceeds the concentration of hydroxyl ions and the water is acidic; at pH greater than 7 there is an inverse relationship between H+ and OH- and the water is alkaline. The presence of various impurities in water affects the pH value, determining the speed and direction of chemical reactions. In natural waters, the value of the pH value is significantly affected by the ratio of the concentrations of carbon dioxide CO2, carbonic acid, carbonate and hydrocarbonate ions. The presence of humic (soil) acids, carbonic acid, fulvic acids (and other organic acids as a result of the decomposition of organic substances) in water lowers the pH to values ​​​​of 3.0 - 6.5. Groundwater containing bicarbonates of calcium and magnesium is characterized by a pH close to neutral. The noticeable presence of sodium carbonates and bicarbonates in water increases the pH value to 8.5-9.5. The pH value of the water of rivers, lakes, groundwater is usually in the range of 6.5-8.5, precipitation 4.6-6.1, swamps 5.5-6.0, sea water 7.9-8.3, and gastric juice - 1.6-1.8! Technological requirements for water for the production of vodka include the pH value< 7,8, для производства пива – 6,0-6,5, безалкогольных напитков – 3,0-6,0. Поэтому в рекомендациях ВОЗ фактором ограничения pH служит не влияние этого показателя на здоровье человека, а технические аспекты использования воды с кислой или щелочной реакцией. При pH < 7 вода может вызывать коррозию metal pipes and concrete, and the stronger the lower the pH. At pH > 8, the efficiency of the disinfection process with chlorine decreases and conditions are created for the precipitation of hardness salts. As a result, WHO experts conclude that "in the absence of a water distribution system, the acceptable pH range may be wider" than the recommended 6.5-8.5. It should be noted that diseases of the human gastrointestinal tract were not taken into account when determining the pH range.

What does the term "stable water" mean?

In the general case, water is called stable if it does not cause corrosion of metal and concrete surfaces and does not emit calcium carbonate deposits on these surfaces. Stability is defined as the difference between the pH of the solution and its equilibrium pHS (Langelier index): if the pH is less than the equilibrium, the water becomes corrosive, if it is more than the equilibrium, calcium and magnesium carbonates precipitate. In natural waters, the stability of water is determined by the ratio between carbon dioxide, alkalinity and carbonate hardness of water, temperature, pressure of carbon dioxide in the surrounding air. In this case, the processes of establishing equilibrium proceed spontaneously and are accompanied by either precipitation of carbonates or their dissolution. The ratio between carbon dioxide, bicarbonate and carbonate ions (carbonic acid derivatives) is largely determined by the pH value. At pH below 4.5, of all the components of the carbonate balance, only carbon dioxide CO2 is present in water, at pH = 8.3, almost all carbonic acid is present in the form of hydrocarbonate ions, and at pH 12, only carbonate ions are present in water. When using water in public utilities, in industry, it is extremely important to consider the stability factor. To maintain the stability of water, adjust the pH, alkalinity or carbonate hardness. If the water turns out to be corrosive (for example, during desalination, softening), then it should be enriched with calcium carbonates or alkalized before being supplied to the consumption line; if, on the contrary, the water is prone to the release of carbonate sediments, their removal or acidification of the water is required. For stabilization water treatment, physical methods such as magnetic and radio frequency water treatment are used, which prevent the precipitation of hardness salts on the surfaces of heat exchangers, the internal surfaces of pipelines. Chemical treatment consists in the introduction of special reagents based on phosphate compounds with the help of dispensers, which prevent the deposition of hardness salts on heated surfaces due to their binding, pH correction by dosing acids or passing water through granular materials such as dolomite (Corosex, Calcite, burnt dolomite), dosing various complexones based on phosphonic acid derivatives that inhibit the processes of crystallization of carbonates of hardness salts and corrosion of carbon steels. To obtain the specified parameters and concentrations of water impurities, water conditioning is used. Water conditioning is carried out by a set of equipment for water purification, its stabilization and dosing of necessary substances, for example, acids to reduce alkalinity, fluorine, iodine, mineral salts (for example, correction of calcium content in the production of beer).

Is it harmful to use aluminum utensils if the aluminum content in drinking water is limited by sanitary standards?

Aluminum is one of the most common elements in the earth's crust - its content is 8.8% of the mass of the earth's crust. Pure aluminum is easily oxidized, covered with a protective oxide film and forms hundreds of minerals (aluminosilicates, bauxites, alunites, etc.) and organoaluminum compounds, the partial dissolution of which by natural water determines the presence of aluminum in ground and surface waters in ionic, colloidal form and in the form of suspensions . This metal has found application in aviation, electrical engineering, food and light industry, metallurgy, etc. Effluent and atmospheric emissions industrial enterprises, the use of aluminum compounds as coagulants in municipal water treatment increases its natural content in water. The concentration of aluminum in surface waters is 0.001 - 0.1 mg/dm3, and at low pH values ​​it can reach several grams per dm3. With technical side, concentrations exceeding 0.1 mg/dm3 may cause discoloration of the water, especially in the presence of iron, and at levels above 0.2 mg/dm3 aluminum hydrochloride flocculation may occur. Therefore, WHO experts recommend a value of 0.2 mg/dm3 as MPC. Aluminum compounds, when taken into the body of a healthy person, have practically no toxic effect due to low absorbability, although the use of water containing aluminum compounds for renal dialysis causes neurological disorders in patients receiving treatment. Some experts, as a result of research, come to the conclusion that aluminum ions are toxic to humans, which manifests itself in the effect on metabolism, the functioning of the nervous system, cell reproduction and growth, and the removal of calcium from the body. On the other hand, aluminum increases the activity of enzymes, helps to accelerate the healing of the skin. Aluminum enters the human body mainly with plant foods; water accounts for less than 10% of the total aluminum input. A few percent of the total aluminum supply is provided by other sources - atmospheric air, medicines, aluminum utensils and containers, etc. Academician Vernadsky believed that all natural elements that make up the earth's crust should be present in the human body to one degree or another. Since aluminum is a micronutrient, its daily intake should be small and within narrow tolerance limits. According to WHO experts, daily intake can reach 60-90 mg, although the real one usually does not exceed 30-50 mg. SanPiN 10-124 RB99 classifies aluminum as a substance with a sanitary and toxicological hazard index with hazard class 2 and limits the maximum allowable concentration to 0.5 mg/dm3.

Sometimes there is a musty or suffocating smell in the water. What is it connected with and how to get rid of it?

When using some surface or underground water sources, an unpleasant odor may be present in the water, causing consumers to refuse to use such water and complain to the sanitary and epidemiological authorities. The appearance of a musty smell in the water can have different causes and the nature of the occurrence. Decaying dead plants and protein compounds can give surface water a putrid, herbal, and even fishy odor. Wastewater from industrial enterprises - oil refineries, mineral fertilizer plants, food plants, chemical and metallurgical plants, urban sewage can cause the appearance of odors of chemical compounds (phenols, amines), hydrogen sulfide. Sometimes the smell occurs in the water distribution system itself, which has dead-end branches in the design, storage tanks(which creates the possibility of stagnation), and is caused by the activity of molds or sulfur bacteria. Most often, the smell is associated with the presence of hydrogen sulfide H2S (characteristic smell of rotten eggs) or (and) ammonium NH4 in the water. In groundwater, hydrogen sulfide in noticeable concentrations is due to oxygen deficiency, and in surface waters, as a rule, it is found in the bottom layers, where aeration and mixing of water masses is difficult. Recovery processes of bacterial decomposition and biochemical oxidation of organic substances cause an increase in the concentration of hydrogen sulfide. Hydrogen sulfide in natural waters is in the form of molecular H2S, hydrosulfide ions HS- and less often odorless sulfide ions S2-. The ratio between the concentrations of these forms is determined by the pH values ​​of water: sulfide - an ion in a noticeable concentration can be found at pH > 10; at pH<7 содержание H2S преобладает, а при рН=4 сероводород почти полностью находится в виде H2S. Аэрация в сочетании с коррекцией рН позволяет полностью избавиться от сероводорода при промышленном производстве бутилированной воды из подземных источников; в быту можно использовать угольные фильтры. Хотя специалисты ВОЗ не устанавливают рекомендуемой величины по причине легкого обнаружения даже следовых концентраций, следует считать ПДК сероводорода равной нулю. Основными источниками поступления ионов аммония в водные объекты являются животноводческие фермы, хозяйственно-бытовые сточные воды (до 2-7 мг/ дм3), поверхностный сток с сельскохозяйственных полей при использовании аммонийных удобрений, а также сточные воды предприятий пищевой, коксохимической, лесохимической и химической промышленности (до 1 мг/дм3). В незагрязненных поверхностных водах образование ионов аммония связано с процессами биохимического разложения белковых веществ. ПДК (с санитарно-токсикологическим показателем вредности) в воде водоемов хозяйственно - питьевого и культурно-бытового водопользования не должна превышать 2 мг/дм3 по азоту.

Does cobalt really have an anti-carcinogenic effect and what amounts of it are acceptable for consumption without harm, but with benefit?

Cobalt is a chemical element, a heavy metal of silver-white color with a reddish tinge. Cobalt is a biologically active element that is part of vitamin B12, constantly present in all living organisms - plants and animals. Like any trace element, cobalt is useful and safe in a narrow range of daily doses of 0.1 - 0.2 mg with constant intake into the human body in total with food and water. In high concentrations, cobalt is toxic. Therefore, it is important to know and control its content in drinking water. The lack of cobalt causes anemia, dysfunction of the central nervous system, loss of appetite. The inhibitory effect of cobalt on the respiration of malignant tumor cells suppresses their reproduction. In addition, this element helps to increase the antimicrobial properties of penicillin by 2-4 times.

Cobalt compounds enter natural waters as a result of their leaching from copper pyrite and other ores, from soils during the decomposition of organisms and plants, as well as with wastewater from metallurgical, metalworking and chemical plants. Cobalt compounds in natural waters are in a dissolved and suspended state, the quantitative ratio between which is determined by the chemical composition of water, temperature and pH values. Dissolved forms are mainly represented by complex compounds, including those with organic substances in natural waters. Divalent cobalt compounds are most characteristic of surface waters. In the presence of oxidizing agents, trivalent cobalt can exist in appreciable concentrations. In unpolluted and slightly polluted river waters, its content ranges from tenths to thousandths of a milligram per 1 dm3, the average content in sea water is 0.5 μg/dm3. The highest concentration of cobalt is found in such products as beef and veal liver, grapes, radishes, lettuce, spinach, fresh cucumber, blackcurrant, cranberries, onions. According to SanPiN 10-124 RB99, cobalt is classified as a toxic heavy metal with a sanitary and toxicological hazard index of hazard class 2 and a maximum allowable concentration of 0.1 mg/dm3.

When using water from your own well, black-gray small grains appear. Isn't it bad to drink such water?

An accurate “diagnosis” requires a chemical analysis of water, but from experience it can be assumed that the “culprit” of such troubles is manganese, which often accompanies iron in groundwater. Even at concentrations of 0.05 mg / dm3, which is two times lower than the maximum allowable, manganese can be deposited as a deposit on the inner surfaces of pipes, followed by flaking and the formation of a black precipitate suspended in water. Natural manganese enters surface waters as a result of leaching of minerals containing manganese (pyrolusite, manganite, etc.), as well as in the process of decomposition of aquatic organisms and plants. Manganese compounds enter water bodies with wastewater from metallurgical plants and chemical industry enterprises. In river waters, the manganese content usually ranges from 1 to 160 µg/dm3, the average content in sea waters is 2 µg/dm3, and in underground waters - hundreds and thousands of µg/dm3. In natural waters, manganese migrates in various forms - ionic (in surface waters there is a transition to high-valent oxides that precipitate), colloidal, complex compounds with bicarbonates and sulfates, complex compounds with organic substances (amines, organic acids, amino acids and humic substances) , sorbed compounds, in the form of manganese-containing suspensions of minerals washed out by water. Forms and balance of manganese content in water is determined by temperature, pH, oxygen content, absorption and release of it by aquatic organisms, groundwater. From a physiological point of view, manganese is a useful and even vital trace element, actively influencing the metabolism of proteins, fats and carbohydrates in the human body. In the presence of manganese, more complete absorption of fats occurs. This element is necessary for a large number of enzymes, maintains a certain level of cholesterol in the blood, and also enhances the action of insulin. After entering the blood, manganese penetrates into erythrocytes, enters into complex compounds with proteins and is actively adsorbed by various tissues and organs, such as the liver, kidneys, pancreas, intestinal walls, hair, endocrine glands. The most important in biological systems are manganese cations in the oxidation state 2+ and 3+. Despite the fact that brain tissues absorb manganese in smaller amounts, the main toxic effect of its excessive consumption is manifested in damage to the central nervous system. Manganese promotes the transition of active Fe(II) to Fe(III), which protects the cell from poisoning, accelerates the growth of organisms, promotes the utilization of CO2 by plants, which increases the intensity of photosynthesis, etc. The daily human need for this element - from 5 to 10 mg - is provided mainly by food products, among which various cereals dominate (especially oatmeal, buckwheat, wheat, corn, etc.), legumes, beef liver. At concentrations of 0.15 mg/dm3 and above, manganese can stain linen and impart an unpleasant aftertaste to drinks. The maximum allowable concentration of 0.1 mg / dm3 is set from the standpoint of its coloring properties. Manganese, depending on its ionic form, can be removed by aeration followed by filtration (pH > 8.5), catalytic oxidation, ion exchange, reverse osmosis or distillation.

The processes of dissolution of various rocks (minerals halite, mirabilite, igneous and sedimentary rocks, etc.) are the main source of sodium entering natural waters. In addition, sodium enters surface waters as a result of natural biological processes in open water bodies and rivers, as well as with industrial, domestic and agricultural wastewater. The concentration of sodium in the water of a particular region, in addition to hydrogeological conditions, the type of industry, is also affected by the time of year. Its concentration in drinking water usually does not exceed 50 mg/dm3; in river waters it ranges from 0.6 to 300 mg/dm3 and even more than 1000 mg/dm3 in areas with saline soils (for potassium no more than 20 mg/dm3), in underground waters it can reach several grams and tens of grams per 1dm3 on large depths (for potassium - similarly). Sodium levels above 50 mg/dm3 up to 200 mg/dm3 can also be obtained from water treatment, especially in the sodium-cation softening process. High sodium intake, according to numerous data, does play a significant role in the development of hypertension in genetically sensitive people. However, the daily intake of sodium with drinking water, even at elevated concentrations, as a simple calculation shows, is 15-30 times lower than with food, and cannot cause a significant additional effect. However, for individuals suffering from hypertension or heart failure, when it is necessary to limit the intake of sodium in total water and food, but who wish to use soft water, potassium - cationic softener can be recommended. Potassium is important in maintaining the automatism of the contraction of the heart muscle, the potassium-sodium "pump" maintains the optimal fluid content in the body. A person needs 3.5 g of potassium per day and its main source is food (dried apricots, figs, citrus fruits, potatoes, nuts, etc.). SanPiN 10-124 99 limits the sodium content in drinking water to MPC 200 mg/dm3; potassium restrictions are not given.

What are dioxins?

Dioxins are a generalized name for a large group of polychlorinated artificial organic compounds (polychlorodibenzoparadioxins (PCDC), polychlordibenzodifurans (PCDF) and polychlorodibiphenyls (PCDF). Dioxins are solid colorless crystalline substances with a melting point of 320-325 ° C, chemically inert and thermostable (decomposition temperature above 750°C).Appear as by-products in the synthesis of certain herbicides, in the production of paper using chlorine, in the plastics industry, in the chemical industry, are formed when waste is burned in waste incineration plants.When released into the environment, they are absorbed by plants, soil and various materials, enter through the food chain into the organisms of animals and, especially, fish.Atmospheric phenomena (winds, rains) contribute to the spread of dioxins and the formation of new sources of pollution.In nature, they decompose extremely slowly (more than 10 years), which causes their accumulation and long-term impact on living organisms. When ingested with food or water, dioxins affect the immune system, liver, lungs, cause cancer, genetic mutations of germ cells and embryonic cells, and the period of manifestation of their action can be months or even years. Signs of dioxin damage are weight loss, loss of appetite, the appearance of an acne-like rash on the face and neck that cannot be treated, keratinization and pigmentation disorders (darkening) of the skin. Eyelid lesion develops. Extreme depression and drowsiness set in. In the future, the defeat of dioxins leads to dysfunction of the nervous system, metabolism, changes in blood composition. Most dioxins are found in meat (0.5 - 0.6 pg / g), fish (0.26 - 0.31 pg / g) and dairy products (0.1 - 0.29 pg / g), and in fat these products of dioxins accumulate several times more (according to Z.K. Amirova and N.A. Klyuev), and practically are not found in vegetables, fruits and cereals. Dioxins are one of the most toxic synthetic compounds. The Acceptable Daily Intake (ADI) is no more than 10 pg/kg of body weight per day (in the US it is 6 fg/kg), which suggests that dioxins are a million times more toxic than heavy metals such as arsenic and cadmium. The maximum allowable concentration in water of 20 pg/dm3 adopted by us suggests that with proper control by sanitary services and daily water consumption of no more than 2.5 liters, we are not in danger of getting poisoned by dioxins contained in water.

What dangerous organic compounds can be in drinking water?

Among the natural organic substances found in surface water sources - rivers, lakes, especially in swampy areas - humic and fulvic acids, organic acids (formic, acetic, propionic, benzoic, butyric, lactic), methane, phenols, nitrogen-containing substances (amines, urea, nitrobenzenes, etc.), sulfur-containing substances (dimethyl sulfide, dimethyl disulfide, methyl mercaptan, etc.), carbonyl compounds (aldehydes, ketones, etc.), fats, carbohydrates, resinous substances (excreted conifers trees), tannins (or tannins - phenol-containing substances), lignins (high molecular weight substances produced by plants). These substances are formed as products of vital activity and decay of plant and animal organisms, some of them enter the water as a result of its contact with deposits of hydrocarbons (oil products). The economic activity of mankind causes pollution of water basins with substances similar to natural ones, as well as thousands of artificially created chemicals, multiplying the concentration of undesirable organic impurities in water. In addition, materials from water distribution networks, as well as chlorination of water for disinfection purposes (chlorine is an active oxidizing agent and readily reacts with various organic compounds) and coagulants at the stage of primary water treatment, contribute additional pollution to drinking water. These contaminants include various groups of substances that can affect health: - humic substances polluting the water supply, petroleum products, phenols, synthetic detergents (surfactants), pesticides, carbon tetrachloride CCl4, phthalic acid esters, benzene, polycyclic aromatic hydrocarbons (PAH), polychlorinated biphenyls (PCBs), chlorobenzenes, chlorinated phenols, chlorinated alkanes and alkenes - carbon tetrachloride (tetrachloromethane) CCl4 entering the purification stages, trihalomethanes (chloroform (trichloromethane) CHCl3, bromodichloromethane, dibromochloromethane, tribromomethane (bromoform)), acrylamide - entering the in the process of water distribution, vinyl chloride monomers, PAHs. If the concentration of natural organic substances in uncontaminated and slightly polluted natural waters usually does not exceed tens and hundreds of µg/dm3, then in waters polluted by wastewater their concentration (as well as the spectrum) is significantly increased and can reach tens and hundreds of thousands of µg/dm3.

A certain part of organic substances is unsafe for the human body and their content in drinking water is strictly regulated. Especially dangerous (hazard class 2 and 1) include substances with a sanitary and toxicological sign of harmfulness, causing a pronounced negative effect on various human organs and systems, as well as having carcinogenic and (or) mutagenic effects. The latter include hydrocarbons such as 3,4-benzapyrene (MPC 0.005 µg/dm3), benzene (MPC 10 µg/dm3), formaldehyde (MPC 50 µg/dm3), 1,2-dichloroethane (MPC 10 µg/dm3), trichloromethane (MPC 30 µg/dm3), carbon tetrachloride (MPC 6 µg/dm3), 1,1-dichloroethylene (MPC 0.3 µg/dm3), trichlorethylene (MPC 30 µg/dm3), tetrachlorethylene (MPC 10 µg/dm3) , DDT (sum of isomers) (MAC 2 µg/dm3), aldrin and dieldrin (MAC 0.03 µg/dm3), ?-HCCH (lindane) (MAC 2 µg/dm3), 2,4 - D (MPC 30 µg/dm3), hexachlorobenzene (MPC 0.01 µg/dm3), heptachlor (MPC 0.1 µg/dm3) and a number of other organochlorine substances. Efficient removal of these substances is achieved using carbon filters or reverse osmosis systems. At municipal water treatment plants, it is necessary to ensure the removal of organic substances from the water before chlorination, or to choose alternative methods of water disinfection to the use of free chlorine. In SanPin 10-124 RB99, the amount of organic substances for which MPCs have been introduced reaches 1471.

Is it harmful to drink water treated with polyphosphates?

Phosphorus and its compounds are extremely widely used in industry, public utilities, agriculture, medicine, etc. Phosphoric acid is mainly produced and, based on it, phosphate fertilizers and technical salts - phosphates. In the food industry, for example, phosphoric acid is used to regulate the acidity of jelly-like products and soft drinks, in the form of calcium phosphate additives in bakery products, to increase water retention in some foods, in medicine - for the production of medicines, in metallurgy - as a deoxidizer and alloying additive in alloys, in the chemical industry - for the production of degreasing and synthetic detergents based on sodium tripolyphosphate, in public utilities - to prevent scale formation due to the addition of polyphosphates to the treated water. Total phosphorus P, which exists in the human environment, consists of mineral and organic phosphorus. The average mass content in the earth's crust is 9.3x10-2%, mainly in rocks and sedimentary rocks. Due to the intensive exchange between mineral and organic forms, as well as living organisms, phosphorus forms large deposits of apatites and phosphorites. The processes of weathering and dissolution of phosphorus-containing rocks, natural bioprocesses determine the content of total phosphorus in water (as mineral H2PO4- at pH< 6,5 и HPO42- pH>6.5, and organic) and phosphates in concentrations from units to hundreds of µg/dm3 (in dissolved form or in the form of particles) for unpolluted natural waters. As a result of pollution of water basins by agricultural (from fields 0.4-0.6 kg P per 1 ha, from farms - 0.01-0.05 kg / day per animal), industrial and domestic (0.003-0.006 kg / day per inhabitant) The concentration of total phosphorus can be significantly increased by sewage, up to 10 mg/dm3, often leading to eutrophication of water bodies. Phosphorus is one of the most important biogenic elements necessary for the life of all organisms. It is contained in cells in the form of ortho- and pyrophosphoric acids and their derivatives, is part of phospholipids, nucleic acids, adenazine triphosphoric (ATP) acid, and other organic compounds that affect metabolic processes, storage of genetic information, and energy accumulation. Phosphorus in the human body is found mainly in bone tissue (up to 80%) at a concentration of 5 g% (per 100 g of dry matter), and the exchange of phosphorus, calcium and magnesium is closely related. The lack of phosphorus leads to rarefaction of bone tissue, increasing its fragility. In the tissues of the brain, phosphorus is about 4g%, and in the muscles - 0.25g%. The daily need of the human body for phosphorus is 1.0 -1.5 g (great need for children). The most phosphorus-rich foods are milk, cottage cheese, cheeses, egg yolk, walnuts, peas, beans, rice, dried apricots, meat. The greatest danger to humans is elemental phosphorus - white and red (the main allotropic modifications), which causes severe systemic poisoning and neurotoxic disorders. Regulatory documents, in particular, SanPiN 10-124 RB 99, set the MPC for elemental phosphorus at 0.0001 mg/dm3 on a sanitary and toxicological basis with hazard class 1 (extremely dangerous). As for the polyphosphates Men(PO3)n , Men+2PnO3n+1 , MenH2PnO3n+1, they are of low toxicity, especially hexametaphosphate used for quasi-softening of drinking water. The permissible concentration established for them is 3.5 mg/dm3 (according to PO43-) with a limiting indicator of harmfulness on an organoleptic basis.

Valves contaminated in this manner are sometimes returned as "failed". There is also a situation where the valves are returned without visible signs of malfunction; however, if a second valve in the same location "loses" again, you can be sure that this is caused by the presence of a bypass in the system, i.e. the occurrence of an unwanted hydraulic channel between the high pressure pipeline and that part of the system where the pressure is reduced.

The most common bypass occurs between an uncontrolled cold water system and a reduced pressure hot water supply system, where a pressure reducing valve is installed at the inlet to the hot water tank.

Somewhere in the system, the pipelines of cold and hot water supply are closed to each other. It can be a thermostatic center mixer, but more often it is an outlet fixture such as single outlet sink mixers, bath or shower thermostatic mixers, etc. To prevent a bypass channel between cold and hot water pipelines, for example, in thermostat mixers, check valves are installed on the cold and hot water inlets.

If the non-return valve installed at the hot water connection does not work properly to cut off, then the pressure from the system cold water can be freely transferred to the hot water pipeline. If the cold water pressure exceeds the working pressure or is higher than the pressure for which the safety valve of the water heater is designed, this will lead to a constant leakage of the safety valve.

In some cases, this situation may only occur during the night, when low water consumption from the mains leads to an increase in static pressure. However, in most cases, the pressure gauge on the pipeline immediately before the pressure reducing valve shows high blood pressure because the check valve downstream of the pressure reducing valve rarely closes completely.

However, the pressure reducing valve remains closed as long as the outlet pressure remains above the set pressure. The valve thus functions as a fully shut-off non-return valve. Furthermore, the D06F series pressure reducing valves are designed so that all outlet parts can withstand a pressure equal to the maximum allowable inlet pressure without compromising valve performance.

In the case where the pressure reducing valve is located at a central point directly downstream of the water meter, the described problem does not occur, since the cold and hot water piping systems are at the same pressure. However, a single branch before a pressure reducing valve, for example to a garage or garden, can cause such a malfunction in a system with a centrally located pressure reducing valve.

For the sake of completeness, it should also be noted that where a separate pressure reducing valve is installed to control a tank with hot water, the expansion of water when heated can cause an increase in pressure above the set level, and up to the set pressure of the safety valve. This can also happen in the case of centrally installed pressure reducing valves, which will result in the bypass described above in the direction opposite to the water flow.

2. Insert it into the connector until it stops.

The tube is fixed with a mechanical clamp. Apply additional force to seal the connection. In this case, the tube will sink another 3 mm and will be tightly compressed by the rubber ring of the connector.

The tube is fixed. Pull the tubing lightly to check the connection.

Make sure the system is depressurized before disconnecting.

Detaching is just as easy.

1. Press the ring at the base, the mechanical clamp will release the tube.

2.Pull out the tube.

Currently, filters operating on the principle of reverse osmosis are becoming more and more popular among consumers. Such filters have a special membrane, and the movement of water through it from a more concentrated solution to a less concentrated one.
The reverse osmosis process has been used as a method of water purification since the early 60s. It was originally used to desalinate sea water. Today, according to the principle of reverse osmosis, hundreds of thousands of tons of drinking water per day are produced in the world.
Improvement in technology has made it possible to use reverse osmosis systems at home. To date, thousands of such systems have already been installed in the world. The water obtained by reverse osmosis has a unique degree of purification. By its properties, it is close to the melt water of glaciers, which is recognized as the most environmentally friendly and beneficial for humans.
The phenomenon of osmosis underlies the metabolism of all living organisms. Thanks to him, nutrients enter every living cell and, conversely, toxins are removed.
The phenomenon of osmosis is observed when two saline solutions with different concentrations are separated by a semi-permeable membrane.
This membrane allows molecules and ions of a certain size to pass through, but serves as a barrier to substances with larger molecules. Thus, water molecules are able to penetrate the membrane, but salt molecules dissolved in water are not.
If there are salt-containing solutions with different concentrations on opposite sides of a semi-permeable membrane, water molecules will move through the membrane from a weakly concentrated solution to a more concentrated one, causing an increase in the liquid level in the latter. Due to the phenomenon of osmosis, the process of water penetration through the membrane is observed even when both solutions are under the same external pressure.
The difference in the height of the levels of two solutions of different concentrations is proportional to the force under which water passes through the membrane. This force is called osmotic pressure.
In the case when an external pressure exceeding the osmotic pressure acts on a solution with a higher concentration, water molecules will begin to move through a semipermeable membrane in the opposite direction, that is, from a more concentrated solution to a less concentrated one.
This process is called reverse osmosis. All reverse osmosis membranes work on this principle.
In the process of reverse osmosis, water and substances dissolved in it are separated at the molecular level, while almost perfectly pure water accumulates on one side of the membrane, and all impurities remain on its other side. Thus, reverse osmosis provides a much higher degree of purification than most traditional filtration methods based on the filtration of mechanical particles and the adsorption of a number of substances using activated carbon.
All reverse osmosis membranes work on this principle. The reverse osmosis process is carried out on osmotic filters containing special membranes that trap organic and mineral impurities dissolved in water, bacteria and viruses. Water purification occurs at the level of molecules and ions, with a marked decrease in the total salt content in water. Many home reverse osmosis filters are used in the US and Europe to purify municipal water with a salt content of 500 to 1000 mg/l; high pressure reverse osmosis systems purify brackish and even sea water (36000 mg/l) to the quality of normal drinking water.
Reverse osmosis filters remove Na, Ca, Cl, Fe, heavy metals, insecticides, fertilizers, arsenic and many other impurities from water. "Molecular sieve", which are reverse osmosis membranes, retains almost all impurity elements contained in water, regardless of their nature, which protects the water consumer from unpleasant surprises associated with inaccurate or incomplete analysis of source water, especially from individual wells.
In the process of reverse osmosis, water and substances dissolved in it are separated at the molecular level, while almost perfectly pure water accumulates on one side of the membrane, and all impurities remain on the other side of the membrane. Thus, reverse osmosis provides a much higher degree of purification than most traditional filtration methods based on the filtration of mechanical particles and the adsorption of a number of substances using activated carbon.
The main and most important element of reverse osmosis plants is the membrane. The original water, contaminated with various impurities and particles, passes through the pores of the membrane, which are so small that pollution practically does not pass through them. In order to prevent the membrane pores from clogging, the inlet flow is directed along the membrane surface, which washes away impurities. Thus, one input stream is divided into two output streams: a solution passing through the membrane surface (permeate) and a part of the initial stream that did not pass through the membrane (concentrate).
The reverse osmosis semi-permeable membrane is a composite polymer of uneven density. This polymer is formed from two layers inextricably linked together. An outer very dense barrier layer about 10 millionths of a cm thick rests on top of a less dense porous layer that is five thousandths of a cm thick. pass through the membrane, creating a permeate flow. The quality of the permeate is comparable to the quality of demineralized water obtained by the traditional H-OH-ionization scheme, and surpasses it in some parameters (oxidizability, silicic acid, iron content, etc.).
The reverse osmosis membrane is an excellent filter and theoretically the content of dissolved minerals in the pure water obtained as a result of filtration should be 0 mg / l (that is, they should not be at all!), regardless of their concentration in the incoming water.
A reverse osmosis membrane is indispensable for ridding water of microbes, since the pore size of the membranes is much smaller than the size of the viruses and bacteria themselves.
In fact, under normal operating conditions, 98-99% of the minerals dissolved in it are recovered from the incoming water. In the pure water obtained as a result of filtration, 6 - 7 mg / l of dissolved minerals remain.
Minerals dissolved in water have an electrical charge, and a semipermeable membrane also has its own electrical charge. Due to this, 98 - 99% of the mineral molecules are repelled from the reverse osmosis membrane. However, all molecules and ions are in constant, chaotic motion. At some point, moving oppositely charged ions are at a very close distance from each other, they are attracted, their electric charges are mutually neutralized and an uncharged particle is formed. Uncharged particles are no longer repelled by the reverse osmosis membrane and can pass through it.
But not all uncharged particles end up in pure water. The reverse osmosis membrane is designed in such a way that the size of its pores is as close as possible to the size of the smallest water molecules in nature, therefore only the smallest uncharged molecules of mineral substances can pass through the reverse osmosis membrane, and the most dangerous large molecules, for example, salts of heavy metals, will not be able to penetrate through her.
In practice, the membrane does not completely retain dissolved substances in water. They penetrate the membrane, but in negligible amounts. Therefore, purified water still contains a small amount of dissolved substances. It is important that an increase in inlet pressure does not lead to an increase in the salt content in the water after the membrane. On the contrary, more water pressure not only increases the performance of the membrane, but also improves the quality of cleaning when using the reverse osmosis method. In other words, the higher the water pressure on the membrane, the more pure water best quality you can get it.
In the process of water purification according to the principle of reverse osmosis, the concentration of salts on the inlet side increases, due to which the membrane may become clogged and stop working. To prevent this, a forced flow of water is created along the membrane, flushing the brine into the drain.
The efficiency of the reverse osmosis process in relation to various impurities and solutes depends on a number of factors: pressure, temperature, pH level, the material from which the membrane is made, and the chemical composition of the inlet water, affect the efficiency of the reverse osmosis system. The degree of water purification in such filters is 85% -98% for most inorganic elements. Organic substances with a molecular weight of more than 100-200 are completely removed; and with less, they can penetrate the membrane in small quantities.
Inorganic substances are very well separated by a reverse osmosis membrane. Depending on the type of membrane used (cellulose acetate or thin-film composite), the degree of purification for most inorganic elements is 85%-98%.
The reverse osmosis membrane also removes organic matter from the water. In this case, organic substances with a molecular weight of more than 100-200 are completely removed; and with less, they can penetrate the membrane in small quantities. The large size of viruses and bacteria virtually eliminates the possibility of their penetration through the reverse osmosis membrane. However, manufacturers claim that the large size of viruses and bacteria virtually eliminates the possibility of their penetration through the membrane.
At the same time, the membrane allows oxygen and other gases dissolved in water to pass through, which determine its taste. As a result, the output of the reverse osmosis system is fresh, tasty, so pure water that, strictly speaking, it does not even require boiling.
In industry, such membranes are made from polymeric and ceramic materials. Depending on the size of the pores, they are used to:
reverse osmosis;
microfiltration
ultrafiltration;
nanofiltration (nanometer - one billionth of a meter, or one thousandth of a micron, that is, 1 nm = 10 angstroms = 0.001 microns.);
Reverse osmosis membranes contain the narrowest pores and are therefore the most selective. They trap all bacteria and viruses, most of the dissolved salts and organic substances (including iron and humic compounds that give color to the water and pathogenic substances), passing only water molecules of small organic compounds and light mineral salts. On average, RO membranes retain 97-99% of all dissolved substances, passing only water molecules, dissolved gases and light mineral salts.
Membrane filter material is cellulose nitrate. As long-term practice has shown, this material provides optimal conditions for the growth of delayed microorganisms, excluding false negative results.
The membrane filter consists of several layers that are connected together and wrapped around a plastic tube. The membrane material is semi-permeable. Water is forced through a semipermeable membrane that rejects even low molecular weight compounds. A schematic representation of the membrane is shown below.
Reverse osmosis membranes are used in many industries where there is a need to obtain high quality water (water bottling, production of alcoholic and non-alcoholic beverages, food industry, pharmaceuticals, electronics industry, etc.).
The use of a two-stage reverse osmosis (water is passed through reverse osmosis membranes twice) makes it possible to obtain distilled and demineralized water. Such systems are a cost-effective alternative to evaporator distillers and are used in many industries (electroplating, electronics, etc.). In recent years, a new boom in membrane technology has begun.
Membrane filters have become more and more used in everyday life. This became possible thanks to scientific and technological achievements: membrane devices became cheaper, specific productivity increased and operating pressure decreased. Reverse osmosis systems allow you to get the purest water that meets SanPiN "Drinking Water" and European quality standards for drinking water use, as well as all requirements for use in household appliances, heating systems and plumbing.
Membrane filtration is indispensable for ridding water of microbes, since the pore size of the membranes is much smaller than the size of the viruses and bacteria themselves.
Microfiltration membranes with a pore size of 0.1-1.0 microns retain fine suspensions and colloidal particles, defined as turbidity. As a rule, they are used when there is a need for coarse water purification or for preliminary water treatment before deeper purification.
When switching from microfiltration to reverse osmosis, the pore size of the membrane decreases and, consequently, the minimum size of retained particles decreases. At the same time, the smaller the pore size of the membrane, the greater the resistance it provides to the flow and the greater the pressure required for the filtration process.
Ultrafiltration (UV) UV membrane retains suspended solids, microorganisms, algae, bacteria and viruses, significantly reduces water turbidity. In some cases, UV membranes effectively reduce the oxidizability and color of water. Ultrafiltration replaces settling, settling, microfiltration.
Ultrafiltration membranes with a pore size of 0.01 to 0.1 µm remove large organic molecules (molecular weight over 10,000), colloidal particles, bacteria and viruses without retaining dissolved salts. Such membranes are used in industry and in everyday life and provide a consistently high quality of purification from the above impurities without changing the mineral composition of water.
In industrial water treatment, hollow fiber membranes are most widely used, the main element of which is a hollow fiber with a diameter of 0.5-1.5 mm with an ultra-filtration membrane deposited on the inner surface. To obtain a large filtering surface, groups of hollow fibers are grouped into modules providing 47-50 m2.
Ultrafiltration allows you to save the salt composition of water and carry out its clarification and disinfection with virtually no use of chemicals.
Typically, the UV unit operates in dead-end filtration mode without discharging the concentrate. The filtration process alternates with backwashing of membranes from accumulated contaminants. To do this, part of the purified water is supplied in the opposite direction. Periodically, a solution of detergents is dosed into the wash water. Rinsing water, which is a concentrate, does not exceed 10–20% of the initial water flow. Once or twice a year, the membranes are intensively circulated with special cleaning solutions.
Ultrafiltration can be used to obtain drinking water directly from a surface source. Since the UV membrane is a barrier to bacteria and viruses, no primary chlorination of the water is required. Disinfection is carried out immediately before the water is supplied to the consumer.
Since the ultrafiltrate is completely free from suspended and colloidal substances, it is possible to use this technology as a pretreatment of water before reverse osmosis.
Nanofiltration (NF) occupies an intermediate position between reverse osmosis and ultrafiltration. Nanofiltration membranes are characterized by a pore size of 0.001 to 0.01 µm. They retain organic compounds with a molecular weight above 300 and pass 15-90% of salts, depending on the structure of the membrane.
Reverse osmosis and nanofiltration are very similar in terms of media separation mechanism, process organization scheme, operating pressure, membranes and equipment. The nanofiltration membrane partially retains organic molecules, dissolved salts, all microorganisms, bacteria and viruses. At the same time, the degree of desalination is lower than with reverse osmosis. The nanofiltrate contains almost no hardness salts (10-15 times decrease), i.e. he is softened. Happens also effective reduction color and oxidizability of water. As a result, the source water is softened, disinfected and partially desalinated.
Modern nanofiltration filters are an alternative to ion-exchange water softeners.
The latest generation of water filters are nano-carbon based filters. They are not yet widespread on the world market, but, despite this, they cost relatively little money. Their advantage over other filters is in the special subtlety of cleaning and the delicacy of cleaning - they do not remove everything from the water, i.e. leave salts and trace elements in the water. At the same time, they purify water at the nanolevel, i.e. work tens and hundreds of times better than analogues - filters based on carbon sorbent.
But the most recognized reverse osmosis membrane filters for water purification due to the unique quality of water achieved after filtration. Such filters effectively cope with low molecular weight humic compounds, which give the water a yellowish tint and impair its taste properties, and which are very difficult to remove by other methods. With the use of membrane reverse osmosis filters, you can get the purest water. Such water is not only safe for health, but also preserves the snow-whiteness of expensive plumbing, does not disable household appliances and the heating system, and just pleases the eye.
Reverse osmosis filters have a number of other advantages. Firstly, contaminants do not accumulate inside the membrane, but are constantly drained into the drain, which eliminates the possibility of their getting into the treated water. Thanks to this technology, even with a significant deterioration in the parameters of the source water, the quality of treated water remains consistently high. The performance can only decrease, which the consumer learns about from the counters built into the system. In this case, the membrane must be washed with special reagents. Such washings are carried out regularly (about 4 times a year) by service specialists. At the same time, the operation of the installation is monitored. Another advantage is the absence of chemical discharges and reagents, which ensures environmental safety. Membrane systems are compact and fit perfectly into the interior. They are easy to operate and do not need attention from the user.
Membrane water treatment systems are quite expensive. But, given the fact that when using "accumulative" systems, you will most likely need several installations of various actions, their total cost will also be expensive. And if we talk about operating costs, then for membrane systems they are much less.
Now reverse osmosis technology is actively developing. Installations are constantly being improved. Modern systems are complete units with water pre-treatment, installed under the sink or on the water supply line.
Osmotic filters are becoming increasingly popular in domestic use thanks to reliability, compactness, ease of use and, of course, the consistently high quality of the resulting water. Many consumers claim that only thanks to reverse osmosis did they recognize the true color of pure water.
Most residential reverse osmosis filters are equipped with composite thin film membranes capable of retaining 95 to 99% of all dissolved substances. These membranes can operate over a wide range of pH and temperature, as well as at high concentrations of impurities dissolved in water.
The most progressive systems for the preparation of drinking water at present are reverse osmosis systems, which provide water at the outlet in terms of purification degree close to distilled. However, unlike distilled, it has excellent taste qualities, since dissolved gases are preserved in it.
The key component of such a system is a semi-permeable membrane, which provides a degree of water purification of up to 98-99% in relation to almost any pollutants. The membrane allows only water molecules to pass through, filtering out everything else. The characteristic pore size of the membrane is 1 Angstrom (10-10 m). Thanks to this purification, dissolved inorganic and organic compounds, as well as heavy metals, bacteria and viruses, are removed from the water.
In some cases, the use of reverse osmosis is necessary. For example, for water softening. Usually, ion exchange resins are used for this, which replace the calcium and magnesium ions responsible for hardness in water with sodium ions. Sodium salts do not form scale and the allowable concentrations of sodium in water are much higher than those of calcium and magnesium. So it's usually okay. But if the hardness is very high, more than 30 mg / eq / l, then in this process there is an excess of sodium. There will be no scale, but you can’t drink such water. This is where reverse osmosis is needed to remove excess sodium - to soften the water.
Today, other types of filters of the membrane-sorption class are also presented on the Russian market. They consist of a membrane block and one or two blocks (depending on performance and resource) for additional purification. In addition, drinking water already purified and stabilized in terms of salt composition undergoes a final 6-12-fold clarification on special fibers and sorbents. Such a combination of numerous methods of purification and clarification of the liquid medium, known among specialists as "water grinding", made it possible to bring the resource of these water purifiers to 50,000-75,000 liters.
The domestic industry also produces compact reverse osmosis filters designed for water purification in field or extreme conditions. Their main advantage is versatility and compactness, you can always take them with you and be able to use the filter at any time. These are telescopic tubes in shape and size with an ordinary fountain pen. Despite their small size, such devices are able to reliably purify 10 liters of water from bacteria, viruses, chlorine, phenol and toxic metals.
But, despite their advantages, not everyone likes osmotic filters. Main argument: What good is it when the water is perfectly clean? After all, it does not contain trace elements. Answering this question, some manufacturers say that a person receives the necessary trace elements not from water, but together with food, because in order to satisfy the daily need, for example, for potassium, you need to drink 150 liters of water, and 1000 liters of phosphorus. l; others are developing special mineralizers so that the water after cleaning with a filter becomes not only clean, but also “alive”, that is, full-fledged for consumption. Such installations have a long resource (4000 - 15000 l) and a high filtration rate (1.5-3 l/min). These filters are expensive - from 150 to 900$, and also require a lot of space for installation.

The reverse osmosis system constantly drains water into the sewer.

Check if this is true. Shut off the water supply to the tank. In order to close the water tank, climb under the sink and close the lever on the tap (blue) at a right angle (90 degrees) to the water flow (hose). If after 30 min. the water still drains into the drain, it's either pressure, or the reverse osmosis membrane, or the valve after the reverse osmosis membrane, or the four-way valve.

Shut off the tank and open the faucet that is installed on the sink. Reverse osmosis should purify water bypassing the tank. If the flow of purified water is small, about the thickness of a pen shaft, the membrane is working properly.

Check the outlet water pressure just before the reverse osmosis membrane. If the pressure is greater than 6 atm. wait until your home's water supply pressure equalizes, or install a pressure reducer. The cost of the reducer that equalizes the pressure from 250 UAH. up to 350 UAH depending on the country of manufacture. The reverse osmosis system requires a pressure of 3 - 4 atm. If the water pressure is less than 3 atm, install a pump, the cost of a pump kit is from 1500 to 2000 UAH.

Check the four-way valve, it should shut off the water supply to the system after a few minutes, with the tap on the storage tank closed. If it does not block, replace the four-way valve (cost 69 UAH).

With a faulty non-return valve, the tank with purified water is full, but the discharge of water into the drain does not stop. Replace the check valve (cost 45 UAH).

Bad taste of water after the reverse osmosis system. If the water after cleaning with a reverse osmosis filter has a taste, then it is most likely that the water is stagnant. Complaints about the bad taste of water after additional upper mineralizer cartridges or bioceramic cartridges are not related to the fact that these filters bring something to the water, but to improper operation of the water filter. There are up to three glasses of water in the water treatment cartridges. This water, like the water stored in the tank, must not be allowed to stagnate. To eliminate extraneous taste and smell, you must either use a mineralizer (bioceramic cartridge) every day, or drain the first few glasses of water.

If all the water after the filter has unusual smell or taste(from both faucet knobs, or in cases where a mineralizer is not installed), water does not stagnate in filter cartridges, but in a water tank. Here, the most common cause of the problem is that the period for replacing the post-carbon cartridge was missed (once a year), or the resource of the tank (hydroaccumulator) was not fully used. If you cannot use the entire volume of the filter during the operation of the filter (tanks are available with a capacity of 15l. - 12l., 11l.-8l. and 8l.-6l.), it becomes necessary to artificially renew the water in the tank once a month. You can turn off the tap in front of the filter and gradually use the excess purified water, you can fill up a large container or simply drain all the water from the tank into the sewer. If the filter will be used by 1-2 people, the smallest tank (8l.) is recommended during installation.

Low pressure from a faucet in a reverse osmosis system. Low pressure from the water filter faucet is most likely due to improper operation of the tank. The speed of water purification by a reverse osmosis filter is small. It can be thought of as a trickle as thick as the shaft of a pen. In order to immediately be able to collect a large vessel or at least a glass, a storage tank (hydraulic accumulator) is provided in reverse osmosis systems. If no water enters the tank, the filter runs idle. When you open the faucet, water squirts and immediately flows in a trickle. If nothing interferes with the flow of water into the tank (the tubes are not pinched and the valve on the tank is open), then the problem is that the tank is not working properly.

The tank is empty and no water flows into it. Open the faucet on the tank by turning the lever on the faucet (blue) parallel to the water flow (hose). Check the inlet water pressure just before the reverse osmosis membrane. If the pressure is less than 3 atm. wait until your home's water supply pressure equalizes, or install a pump. The cost of a pump-action kit for increasing pressure for a water purification filter is from 1500 UAH. up to 2000 UAH depending on the country of manufacture.

The tank is full and no water comes out of it. Open the faucet on the tank by turning the lever on the faucet (blue) parallel to the water flow (hose). If the tap on the tank is open and there is no mechanical blockage of the flow of water that must be drawn in and out of the tank, the point is the internal pressure of the water tank. If the tank was originally working, and it was not subjected to any external influence, it is necessary to increase the internal pressure of the water tank. Unscrew the cap on the side of the tank. Under the cap there is an ordinary nipple for pumping air, the same as on the tires of a car or bicycle. Pump up the pump to a level of 0.5 - 1.0 atm. If the water tank still does not fill or dispense water, replace the tank. The cost of an iron tank for water 8 liters 570 UAH.

reverse osmosis system slowly picks up water. Open the faucet on the sink. If the flow of water is small, about the thickness of a pen shaft, reverse osmosis works fine. Check the degree of soiling of the pretreatment water cartridges by appearance, if you have transparent flasks, or unscrew the flasks and check the degree of contamination directly. If due to the service life or the deterioration of the quality of the water supplied to the reverse osmosis, the pre-treatment cartridges are out of order, replace them. Check the inlet water pressure just before the reverse osmosis membrane. If the pressure is less than 3 atm., wait until the water supply pressure of your house equalizes, or install a pump. The cost of a pump that increases pressure is 1500-2000 UAH. Press the ring against the fitting in front of the post-carbon cartridge and pull out the hose. If the flow of purified water is as thick as a pen shaft, then there is a mechanical blockage on the way from the reverse osmosis membrane to the faucet. Step by step check all connections of the water filter after the membrane. If the flow of purified water occurs drop by drop, then the reverse osmosis membrane, due to the service life, or the deterioration in the quality of the water supplied to it, has failed. The cost of a reverse osmosis membrane is from 350 UAH. up to 700 UAH depending on the rate of purification of the reverse osmosis membrane.

The correct operation of a reverse osmosis system as well as its performance depends on several variables:

1. The quality of the incoming water (the norm of total mineralization is 200-500 ppm =<1500 мг/л, норма жесткости воды <10 мг-экв/л)
2. Incoming water pressure (norm 3 - 4 atm)
3. Inlet water temperature (standard 15 °C - 25 °C).

So, for example, when the quality of the incoming water deteriorates (high total mineralization of more than 500 ppm) and its temperature decreases (in winter, the water in the water supply system is less than 15 ° C), for the effective operation of the reverse osmosis system, an inlet pressure of at least 4 atm is required. For lower pressures, a pressure booster pump kit must be installed.

Total mineralization 500 ppm, temperature 15 °C, pressure 3 atm - THE SYSTEM WORKS EFFICIENTLY.

Total mineralization >500 ppm, temperature<15 °C, давление 3 атм - THE SYSTEM DOES NOT WORK EFFICIENTLY.

Total mineralization >500 ppm, temperature<15 °C, давление >4 atm - THE SYSTEM WORKS EFFICIENTLY.

Reverse osmosis is the most common technology for deep purification of tap water today. It is based on the use of a partially permeable membrane, which is able to purify water from salts and other unwanted inclusions.

The principle of water purification by reverse osmosis is quite simple: under pressure, water molecules pass through the “sieve” of a semi-permeable membrane, then through the final carbon filters, where foreign odors and tastes are finally removed from the water, its acid-base balance is normalized. The output is ultra-filtered water, completely suitable for drinking and cooking.

All larger particles of the source water are retained and sent to the drainage (sewerage) through the reverse osmosis system.

What to check in a reverse osmosis system if the filter is not working correctly

Structurally, this filtration system consists of several cartridges with carbon filters and a membrane, as well as a tank for purified water.


Reverse osmosis systems, like any other filter elements, can become clogged over time, some of its elements may not work correctly, causing the filter performance to decrease.

If the filter makes extraneous sounds, vibrates, runs slowly, does not drain water, or, conversely, sends a large amount of water to the drain, then the following parameters should be checked:

• Water pressure in the plumbing- the most common cause of reverse osmosis filter failures. It should be at least 2.5-3 atmospheres (different manufacturers have different requirements for this parameter). At lower pressures, the performance of the system drops sharply - water is drawn into the reservoir very slowly. In this case, a large amount of water will go to the drain.
• Permeability of pretreatment cartridges. In case of any interruptions in the operation of the reverse osmosis system, it is necessary to measure the pressure before and after the pre-filter, since clogged pre-filters reduce the pressure on the membrane.
• Tank pressure. Initially, all tanks are pumped up at the factory (in an empty tank, the pressure should be in the range from 0.25 to 0.6 atm). Depending on the pressure in the water supply system, it may be necessary to adjust the pressure in the empty tank.
• The operation of the valve that blocks the discharge of water. When filling the tank with purified water, the discharge of water into the drain must stop. If water continues to leak into the sewer, then the problem is in the valve.

Typical failure cases and methods for their correction

In the event of serious problems (damage to the membrane, leakage of the tank, etc.), it is required reverse osmosis repair. However, very often malfunctions are local in nature and you can fix them yourself.

Here is a list of the most common problems and how to fix them:

1. Water constantly flows into the drain.

Possible reasons:

• insufficient pressure - if the actual inlet pressure is lower than required by the filter manufacturer, then a booster pump must be installed;
• replaceable filter cartridges are clogged - they need to be replaced;
• the shut-off valve is faulty - if, even after a few minutes, the water continues to flow out of the drain pipe when the tap on the storage tank is closed, the shut-off valve needs to be replaced.

1. Leaks.

Possible reasons:

• non-hermetic connection of tubes - the edges of the tubes are unevenly cut or they are not inserted all the way;
• loosely tightened threaded connections - check and tighten all available nuts;
• there are no sealing rings on the connections - install;
• high pressure (above 6 atmospheres), sudden surges - install a reduction gear in front of the first prefilter;

1. The tank is not full.

Possible reasons:

• the first connection of the system - the tank is filled within one and a half to two hours;
• clogged cartridges and / or reverse osmosis membrane - replace them;
• the check valve in the membrane flask is clogged - unscrew and rinse under running water, put in place;
• the drain water flow limiter is clogged - replace;
• too high or insufficient pressure in the tank - all the water is drained from the tank and the pressure in the nipple is checked using a car pump with a pressure gauge. At high pressure in the pipeline (3.5-6 atmospheres), the pressure in the tank can be 0.5-0.6 atm. If there are no more than 2 atmospheres in the water supply, then in the tank it can be lowered to 0.25-0.4 atm. High inlet pressure can cause noise and vibration during system operation. If the pressure in the water main is below 2.5 atm, filter manufacturers recommend additionally installing a booster pump.

1. Water flows very slowly:

• low pressure on the main pipeline - if the inlet pressure is lower than required by the instructions, a booster pump must be installed;
• low pressure in the tank - check and correct;
• tubes are pinched - check, eliminate kinks;
• clogged cartridges and / or reverse osmosis membrane - replace them;
• too cold supply water - operating temperature - +4-40°C.

1. White water comes out of the faucet- a sign of the presence of air in the system, after a few days of osmosis operation, the problem will disappear.

1. Water after filtration has an unpleasant taste (color, smell).

Possible reasons:

• the order of connecting the tubes is violated - compare with the diagram in the instructions, correct if necessary;
• the membrane is clogged and / or the life of the cartridges has ended - replace it;
• not all the preservative has been washed out of the tank - empty the tank several times and refill it.

1. Noise and vibration during system operation, water does not enter the drain:

• high pressure (more than 6 atmospheres), sharp jumps - it is required to install a reduction gear in front of the first prefilter;
• the water flow restrictor to the drain is clogged - remove the blockage or replace the restrictor.

VIDEO INSTRUCTION

Membrane test

The reverse osmosis membrane may fail earlier than the declared resource for the following reasons:

1. too contaminated source water.
2. low pressure (in this case, excess water passes through the membrane).
3. Concentrate flow restrictor defective.

To check the performance of the membrane, the amount of water going to the drain and the amount of treated water should be measured. It is considered normal reverse osmosis efficiency 5-15%, i.e. 85-95% of the water goes to the drain.

The easiest express way to reliably check the performance of the membrane is to purchase a TDS meter. This small salt meter, worth about 1000 rubles, allows you to find out the content of impurities in water.

After osmosis, the TDS meter should show no more than 15 units. If the indicator is higher, then the membrane is not working efficiently and needs to be replaced.