Devices with a membrane for water purification. Household membrane filters - pros and cons. Types of membrane filters by design

Tsugunov Anton Valerievich

Reading time: 5 minutes

Tasteless tap water is the scourge of residents of big cities. Even after boiling it leaves an unpleasant taste in the mouth. In addition, some experts claim that even boiling cannot cleanse it of harmful impurities and microbes. If you live in an apartment and suffer from bad water, then a membrane filter for water purification will help you.

What is a membrane filter?

All filters perform the function of retaining harmful impurities. At the end we get tasty water that you can boil or drink right away. The membrane system, operating on the principle of reverse osmosis, does not allow any harmful substances to pass through, does not accumulate them, and, thanks to its design, washes them into the drain. It has pores through which only water and oxygen can pass. There are several types of materials for the production of such a filter: lavsan, polyurethane and others.

The first such systems were invented back in the 19th century, but the prototype of a modern membrane was released only in the 1960s. It is believed that these are the best water purification systems of all existing ones. They retain not only large debris, but also small particles, purifying water at the molecular level.

All major Russian and foreign companies producing water filters have membrane designs in their product range. First of all, they are in demand among apartment residents in big cities.

Externally, the device is a plastic cylindrical box, inside of which there is a membrane and one or more prefilters. It is connected to cold water and discharged to the sink with a separate tap. Each filter has its own service life, since over time it becomes dirty and cannot perform its functions.

There are membrane filters that work differently. They are placed in a container with water, it passes through the membrane and, according to the principle of communicating vessels, comes out cleaned. The use of such a filter is justified in camping conditions when there is no running water nearby.

In a travel filter, the membrane cartridges need to be cleaned from time to time. You can wash them with clean water or use special chemicals. They are selected depending on the type of contamination. Acidic ones remove salts well, and alkaline ones remove organic and biological compounds.

Varieties by membrane type

There are several types of membrane filter systems. They differ in type of design and pore size. Filters with small holes are considered the best, as they purify water well.

Membrane types:

1. Microfiltration. Provides rough water purification and is used at the preparatory stage. Such a filter will cope with cloudy wastewater, but in the future it will require more subtle cleaning.
2. Ultrafiltration. This type of membrane can purify water from high molecular weight compounds and bacteria. It is usually used in industrial enterprises, as it does not remove salts from water.
3. Nanofiltration. Well suited for hard domestic water. In addition to bacteria, it removes chlorine and heavy metals from water.
4. . This system has the smallest holes and traps all substances and contaminants harmful to humans. Salts, bacteria, viruses, and petroleum products are neutralized by 98%. With the help of such filters, sea water can be purified and desalinated; they are used in the production of bottled water, in pharmacology and microbiology.

Types by type of construction

By type of design, filters are divided into:

• Tubular. The cleaning element consists of porous tubes. They can be made of metal-ceramic, plastic,... The diameter of the pipe can reach several centimeters. There are symmetrical and asymmetrical membranes. In the former, the pores are evenly distributed, in the latter, one wall has a greater concentration of holes than the other. Water is supplied under pressure into this pipe, and the output is pure liquid, and in a separate container - a concentrate of harmful substances.

• Rolled. This filter is a membrane wound like a roll onto the main pipe. Through a special hole, water enters it and flows in a spiral, simultaneously being purified. Clean water flows through the main pipe, and harmful substances exit from another hole. Such systems are cheap to produce, but quickly become dirty during operation.
• Hollow fiber. They consist of membrane tubes that are placed in a filtration apparatus. This significantly increases the working surface, but such filters quickly become clogged and are difficult to clean.

• Disk. They are for laboratory use only and are not used to purify domestic drinking water. The filter element is made in the form of a flat disk. The operating principle of this design is that water is poured into a reservoir in which a piston with a membrane moves. It can be compared to a household French press. Only the filter has several pistons to increase the amount of filtered water. Clean water goes to the consumer's tap, and harmful substances are deposited in a special tank.

Do not worry that all layers of the disk are of chemical origin; the use of such a filter is absolutely safe for health.

Advantages and disadvantages

Compared to other types of filter systems, the membrane design has the following advantages:

• Easy to operate and maintain.
• Good degree of cleaning.
• Small sizes.
• Availability of hiking varieties.

O.V. Mosin

MEMBRANE WATER PURIFICATION TECHNOLOGY AND MEMBRANE FILTERS

About 40 years ago, a fundamentally different water purification technology began to develop - membrane technology. It is based on passing water under pressure through a semi-permeable membrane and dividing the water into two streams: filtrate (purified water) and concentrate (concentrated solution of impurities). The phenomenon of water passing through a film from a low-concentrated solution to a more concentrated solution was discovered back in the 18th century. This phenomenon is called osmosis, and the film that allows water to pass through is called a membrane. The phenomenon of osmosis underlies the metabolism of all living organisms. Thanks to it, nutrients enter every living cell and, conversely, waste products are removed. The phenomenon of osmosis occurs when two salt 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 molecules of salts 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. It was found that this process continues until a certain difference in pressure is established between the solutions, the so-called osmotic pressure - the force under which water passes through the membrane. In the 60s of the twentieth century. It was discovered that if pressure greater than osmotic pressure is artificially applied to a concentrated solution, the reverse process will occur: water molecules will move from the concentrated solution to the dilute one. This process is called "reverse osmosis". In the process of reverse osmosis, water and the substances dissolved in it are separated at the molecular level, while almost perfectly clean water accumulates on one side of the membrane, and all contaminants remain on the other side. Then scientists came to the conclusion that the phenomenon of reverse osmosis can be used to purify water from various impurities, since 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. In addition, the reverse osmosis method is much simpler and cheaper to operate compared to ion exchange systems. Reverse osmosis was originally used to desalinate seawater. Gradually, membranes with different pore diameters began to be manufactured, respectively, providing different purity of the output water.

Membrane processes can be classified according to the size of particles retained into the following types:

Microfiltration (MF),
ultrafiltration (UF),
nanofiltration (NF),
reverse osmosis (RO).

When moving from microfiltration to reverse osmosis, the pore size of the membrane decreases and, therefore, the minimum particle size retained decreases. Moreover, the smaller the pore size of the membrane, the greater the resistance it has to flow and the greater the pressure required for the filtration process.

Microfiltration membranes with a pore size of 0.1-1.0 microns retain small suspended matter and colloidal particles, defined as turbidity. As a rule, they are used when there is a need for rough water purification or for preliminary water preparation before deeper purification.

Ultrafiltration membranes with pore sizes from 0.01 to 0.1 microns remove large organic molecules (molecular weight greater than 10,000), colloidal particles, bacteria and viruses, without retaining dissolved salts. Such membranes are used in industry and in everyday life and provide consistently high quality purification from the above-mentioned impurities, without changing the mineral composition of the water.

Nanofiltration membranes are characterized by pore sizes from 0.001 to 0.01 microns. They retain organic compounds with a molecular weight above 300 and allow 15-90% of salts to pass through, depending on the structure of the membrane.

Reverse osmosis membranes contain the narrowest pores and are therefore the most selective. They retain all bacteria and viruses, most of the dissolved salts and organic substances (including iron and humus compounds that give color to water and pathogenic substances), allowing only water molecules of small organic compounds and light mineral salts to pass through. On average, RO membranes retain 97-99% of all dissolved substances, allowing only water molecules, dissolved gases and light mineral salts to pass through. Such 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 two-stage reverse osmosis (water is passed through reverse osmosis membranes twice) allows you to obtain distilled and demineralized water. Such systems are a cost-effective alternative to evaporative distillers and are used in many industries (electroplating, electronics, etc.). In recent years, a new boom in membrane technology has begun. Membrane installations have become more and more used in everyday life. This became possible thanks to scientific and technological advances: membrane devices became cheaper, specific productivity increased and operating pressure decreased. Reverse osmosis systems allow you to obtain 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.

When writing the article, materials from the site were also used (authorship: Anna Titova):
www.osmos.ru/prom/info.html

Advantages of using reverse osmosis membranes

Reverse osmosis systems have received the greatest recognition due to the unique quality of water achieved after filtration. Such membranes effectively cope with low molecular weight humic compounds, which give water a yellowish tint and impair its taste, and which are very difficult to remove by other methods. Using membrane reverse osmosis systems you can obtain the purest water. Such water is not only safe for health, but also preserves the snow-white appearance of expensive plumbing fixtures, does not damage household appliances and heating systems, and is simply pleasing to the eye.

Membrane systems also have a number of other advantages. Firstly, contaminants do not accumulate inside the membrane, but are constantly drained into the drainage, which eliminates the possibility of them getting into the purified water. Thanks to this technology, even with a significant deterioration in the parameters of the source water, the quality of the purified water remains consistently high. The performance may only decrease, which the consumer will know from the meters 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 use and do not require user attention.

However, membrane water purification systems are quite expensive. But, given that when using “storage” systems, you will most likely need several installations of different actions, their total cost will also not be cheap. And if we talk about operating costs, then for membrane systems they are much lower.

Membrane technology is actively developing. The installations are constantly being improved. Modern systems are almost completely automated, equipped with a locking system in case of power outages and dry-running protection. Membrane filtration is becoming increasingly popular in household use due to its reliability, compactness, ease of use and, of course, the consistently high quality of the resulting water. Many claim that it was only thanks to reverse osmosis that they learned the true color of pure water.

The ISTOKI company offers a wide range of models of reverse osmosis units for household, semi-industrial and industrial use. The WATERLIGHT X-RO series units produce up to 190 liters of high quality drinking water per day and are a good alternative to bottled water. Equipment of this class is characterized by small size, ergonomic design, ease of installation and maintenance, which allows it to be used in everyday life.

Semi-industrial reverse osmosis units of the BUDGET RO series with a capacity of up to 100 liters per hour are used for the preparation of both drinking water in cafes, restaurants, hotels and process water in laboratories and enterprises where there is a need for distilled or demineralized water.
PALLAS XL RO units are used for water treatment in the food and electronics industries, pharmaceuticals, and in the production of alcoholic and non-alcoholic beverages. High productivity, low energy consumption, balanced cost/quality ratio are the advantages of this equipment.

Why membrane filtration?

Membrane filtration is indispensable for ridding water of microbes. The principle of the membrane filtration method is the concentration of microorganisms present in the analyzed sample on the surface of a membrane filter with a pore size of 0.45-0.65 microns by passing the sample through the filter. After filtering the sample, the filter with retained microorganisms is placed on a nutrient medium and incubated under appropriate conditions.

The membrane filtration method has the following advantages:

quantitation
High accuracy
Study of large volume samples
Eliminating the influence of growth inhibitors
Saving nutrient media
Save time
Documenting the result

According to the opinion of META JSC microbiologist E.V. Andreeva The membrane filtration method solves all the disadvantages of water purification from microbes:

If the water sample being tested is expected to have low levels of microorganisms, we may take a large sample volume. During filtration, all microbes will be retained on the membrane.

1.To eliminate the influence of natural bacteriostatics, the membrane can be washed with saline solution or distilled water after filtering the sample.

2. The filtration process takes a little time (when using a 47 mm unit and a 0.45 micron filter - the filtration rate at 90% vacuum is 400-600 ml/minute, depending on the origin of the filter).

3.The equipment is compact and does not require a large workplace

The vacuum filtration unit for the analysis of liquid samples is made of stainless steel, which makes it durable, easy to use, and allows for flame treatment.

Membrane filters and growth media will also be required for operation.

Nutrient media can be prepared independently, which will require additional time, personnel, and equipment.

But it is more convenient and more profitable to use nutritious cardboard substrates (PCB).

PCP is a disk of sorbent material, impregnated with a selective nutrient medium, and then dried under special conditions and sterilely packaged in a plastic Petri dish. Activation of the nutrient medium is carried out immediately before use by wetting the substrate with sterile water. Sterile membrane filters are supplied with the substrates.

Membrane filter material is cellulose nitrate. As many years of practice have shown, this material provides optimal conditions for the growth of detained microorganisms, eliminating the possibility of obtaining a false negative result.

The PKP manufacturing process is standardized and certified according to international ISO and GMP standards. This means that, using PCP, you are insured against the influence of the human factor on the result of the analysis, when the preparation of the nutrient medium does not strictly follow the recipe, which leads to the creation of unsatisfactory conditions for the growth of microorganisms. Or when contamination is accidentally introduced into a sterilized environment, causing a false positive result.

Procedure for carrying out analysis by membrane filtration using PCP :

Questions and answers

What does a membrane filter consist of?

The membrane filter consists of several layers that are joined together and wrapped around a plastic tube. The membrane material is semi-permeable. Water is forced through a semi-permeable membrane, which rejects even low molecular weight compounds.

Do membrane units remove bacteria from water?

YES! The size of the elements passed through the membrane is much smaller than the size of bacteria and viruses.

What does purified water taste like?

The taste of water depends on the composition of the original (unpurified) water and the number of filter elements. If the installation purifies 95% of impurities, then the water tastes the same as distilled water or bottled water or natural spring water (with reduced mineral content).

How will purified water affect cooking?

Reverse osmosis purification systems remove invisible elements from water that mask the real taste of cooked dishes. This is especially true for drinks. By using purified water, you can use less coffee and still get the full flavor of the drink. It is ideal to prepare cocktails, juices, and beer using purified water. Manufacturers of alcoholic beverages who want to achieve impeccable quality of their drinks use purified water using the reverse osmosis method. And naturally you will forget about the sediment that appears after boiling the water.

Are beneficial minerals removed during the cleaning process?

Almost all the minerals required by humans are consumed through food. A very small percentage of beneficial minerals are consumed in water. Don’t worry, you may consume one percent less useful minerals, but you definitely won’t get harmful minerals and chemical elements from your water. In addition, it should be borne in mind that tap water is not initially mineralized and this water is taken mainly from surface sources (rivers, reservoirs), which contain more contaminants than useful minerals.

Where is the reverse osmosis unit installed?

Typically, a water purification unit is installed in the kitchen under the sink. A separate tap for purified water is located outside. Everything necessary for installation (taps, fittings, etc.) is included in the installation kit.

How should the cleaning system be maintained?

It is necessary to change pre-filters in a timely manner (approximately once every six months). You can carry out this operation yourself.

When is it necessary to change the membrane filter?

Replacing the membrane filter may be necessary if the installation begins to produce noticeably less water or its taste changes. Typically, the service life of a membrane filter with proper operation and timely replacement of pre-filters is 2 - 3 years.

What factors influence the quality and quantity of clean water?

There are four main factors influencing the quality and quantity of purified water produced:

1 - Pressure. The higher the pressure, the greater the quantity and higher the quality of water purification produced by the installation.

2 - Temperature. For ideal cleaning, water must be at a certain temperature. Recommended water temperature is 24°. Reducing the water temperature to 5° will reduce productivity by half.

3 - Contamination of source water. The higher the contamination of the source water, the lower the productivity of the installation. High water contamination can be compensated by increasing pressure.

4 - Membrane. Not all membranes are the same: some are more productive, some have an increased degree of purification, some have an increased service life due to increased friction resistance. We use only impeccable quality membranes that have been certified by NSF and have shown the best performance during operation.

Characteristics of domestic ceramic membrane filters

Membrane filter manufacturers

Membrane filters for fine water purification from the Geyser company

One of the most famous Russian companies producing membrane filters is the Geyser company. It produces efficient membrane filters, consisting of three housings and installed in a cabinet under the sink. The large resource of the filter material used allows for deep cleaning from the most common contaminants - chlorine, iron, hardness salts, heavy metals, etc., as well as bacteria and viruses. At the first stage, water passes through a mechanical cleaning cartridge, which removes insoluble suspensions - sand, rust, silt, sediment. The size of the particles retained depends on the size of the pores of the cartridge. The second-stage cartridge, synthesized using a unique method, is a highly porous polymer of combined action: thanks to ion exchange, water is purified from dissolved iron and heavy metals, and the presence of silver in the polymer material prevents the proliferation of filtered bacteria. This “know-how” of the company is characterized by increased filtration speed and the possibility of regeneration at home, which greatly increases its resource. And at the final stage, the water passes through granular activated carbon from coconut shells.

It should be remembered that membrane systems have no equal in terms of cleaning efficiency: it reaches almost 100% for any type of contaminant. Suffice it to say that the list of impurities to be removed alone takes up more than one page. Through the smallest pores of a semi-permeable thin-film membrane, having a size of about 0.0001 microns, only water and oxygen molecules can leak under pressure, and all impurities remaining on the other side of the membrane are drained.

Deep cleaning of the membrane can only be done with water that has undergone preliminary comprehensive cleaning. This initial stage is necessarily present in all membrane systems, but in the Geyser-6 system the pre-treatment scheme was developed specifically for Russian conditions. Removal of sand, rust and other insoluble suspended matter is carried out by a mechanical cartridge with cells up to 5 microns, and a cartridge based on high-quality coconut carbon and special filter material sorbs dissolved compounds of iron, aluminum, heavy and radioactive metals, free chlorine and microorganisms. To increase the resource, the second cartridge can be replaced with a proprietary Geyser ion-exchange filter cartridge, the possibility of repeated regeneration of which increases the duration of its use several times. The last stage of the preliminary stage is very important, where the final purification from the smallest doses of chlorine and organochlorine compounds, which have a destructive effect on the membrane material, occurs on a pressed coconut carbon cartridge. Then the water is supplied to the membrane, after passing through which drinking water of the highest purification class is obtained. And in order to remove dissolved gases from it, the water at the final stage is passed through high-quality pressed activated carbon with the addition of silver.

To enrich pure water with mineral composition, the Geyser company has developed a special mineralizer “Vita”. The Geyser-6 system is the only one among membrane filters equipped with a mineralizer. For example, the price of this entire system is 7,300 rubles; replaceable cartridges: mechanical - 80 rub. (resource 3500 l), cartridge made of granulated carbon or ion exchange cartridge - 280/460 rubles (resource 6000/25000 l), carbon post-filter - 260 rubles (resource 6000 l), mineralizer - 620 rubles. (resource 6000 l), membranes - 1300 rub. (resource 2-3 years). The cost of cleaning is 645 rubles. per 1000 l. Today, Geyser brand membrane filters are among the most effective membrane units and are very popular.

NEROX membrane filters

Another well-known manufacturer of household membrane filters is NEROX. NEROX is the most efficient, safe and unpretentious filter available on the market today.

NEROX filters are deservedly popular among the population of the CIS countries, in mobile units of the Ministry of Emergency Situations and army units. This model is also popular among travelers, tourists, and fishermen.

The NEROX filter features:

High degree of purification;
Availability of a warning system for filter element contamination (reduced productivity, eliminated by washing);
Performance;
Filtration can be increased by the provided joining of filter elements;
The filter does not require replaceable cartridges, only periodic washing is required;
The filter element is environmentally friendly: it does not contain any sorbents or other chemical elements.

The filter is manufactured by the research and production enterprise "Simpex and the Red Cross".

And the heart of the membrane filter - the track membrane - is manufactured at the world-famous Joint Institute for Nuclear Research in Dubna.

A film of lavsan (or any other polymer) is processed by a stream of high-energy krypton ions accelerated at the Dubna cyclotron. The energy of the ions is set so that no radiation occurs in the material, but so that the ions penetrate the film through. Each ion leaves a trace in the lavsan of the material it damaged, called a track (hence the name “track”).

The drip mode of filter operation is the simplest and most reliable indicator of monitoring the performance and integrity of the membrane.

The geography of application of NEROX filters is very wide. This is, first of all, the Chernobyl zone and cholera outbreaks in Russia, Ukraine, Moldova, where they reached through the International Federation of the Red Cross (Geneva), then assistance to the population of countries in Africa, South America, India during floods, providing assistance to the population of Chechnya, Yugoslavia in a period of hostilities and devastation. Experience of use has shown that there are no comments.

DISK-MODULAR SYSTEM AQUA-GLOBUS®

DTK modular system
excellent quality drinking water
high filtrate selection in relation to the source water
long operating time of membranes (up to 10 years)
easy membrane cleaning process
low degree of formation of a polarized layer on membranes and very low membrane blocking
periodic or continuous operation of the filter

All AQUA-GLOBUS® devices undergo careful monitoring of the quality of water produced through membrane filtration of tap water.

AQUA-GLOBUS® FILTRATION SYSTEM FOR DRINKING WATER

The disk is a tubular modular system.

The patented AQUA-GLOBUS® is a modern form for molecular separation, for desalination and purification of city water based on effective and economic reverse osmosis.

A set of membranes between guide plates is placed in the center of the ball. The special design allows for quick monitoring and, if necessary, replacement of membranes. The arrangement of the guide plates and membranes makes it possible to achieve a high water velocity above the surface of the membranes with a relatively small volume of initial water. An open flow channel above the surface of the membranes guarantees optimal operation and cleaning.

The membranes are located between the guide plates. The source water, passing over the membrane, does not mix with clean water due to the seals located in the center of the shaft. The filtrate drainage system - environmentally friendly water - is integrated into hydraulic plates - seals. The special design of the guide plates guarantees an open channel for the flow of source water.

Octagonal or round membrane pads are sealed by durable ultrasonic welding. This welding technique has been proven over many years of experience with various products and different types of membranes. A very short path of liquid movement over the membrane with a change in flow direction by 180° prevents the formation of a polarization layer - deposits on filtration membranes.

In general, AQUA-GLOBUS® has little resistance to blocking and fouling of filtration membranes. Therefore, membranes do not need to be changed for a very long time. Due to the complexity of manufacturing individual filter parts and the lack of necessary material, the company manufactures almost all parts in Germany. The devices are assembled in St. Petersburg.

Membrane filters WATER DOCTOR

Drinking water filters WATER DOCTOR are designed for purification of water from surface sources of class I-II, from underground sources of class I-III and post-purification of drinking water.

100% purification from common (TCB) and thermotolerant coliform bacteria (TCB), as well as pathogenic bacterial agents: causative agents of cholera, salmonellosis, plague, etc.!

In all models of drinking water filters WATER DOCTOR, a high-tech “track membrane” is used as the last finishing stage of water purification, used for medical purposes to filter blood and its preparations.

Advantages of drinking water purification filters WATER DOCTOR

Unlike other purification systems, including those based on track membranes, WATER DOCTOR drinking water filters 100% purify water from 2- and 3-valent iron, aluminum, color, turbidity, up to 99% purify free and bound chlorine, pesticides, heavy metals and petroleum products, while leaving salts, electrolytes and trace elements necessary for humans in the filtered water.

ATTENTION!!! 100% purification from common (TCB) and thermotolerant coliform bacteria (TCB), as well as pathogenic bacterial agents: causative agents of cholera, salmonellosis, plague, etc. Each cleaning performance indicator is confirmed by numerous research and testing protocols in leading accredited testing centers.

MODULAR TECHNOLOGY BY ROKEM SERVICE SAINT PETERSBURG

The main and important part of the installation is the membrane filter (disc-ball module). This modular technology consists of proven and reliable guide plates, between which are ultrasonically welded membrane “cushions”. The filter container consists of two spheres with flanges for installation. Hydraulic or guide plates have an open and short channel for the movement of source water over the membranes. This reduces the formation of deposits on membranes and ensures high quality water with efficient filtrate collection. The advantages of the filter design also include effective cleaning of the membranes, which leads to a long service life of the filter without replacing them. Filter maintenance and membrane replacement are very simple due to the simplicity of filter assembly.

HYDRO DISKS
Between the hydraulic discs there are membranes, the ends of which are sealed by ultrasonic welding. Guide plates ensure efficient flow of source water over the filter surface of the membranes. A centrally located common filter tank allows filtered clean water to be directed from the filter to the clean water storage tank.

MEMBRANES
The filter module is equipped with membrane filtration “cushions”, the ends of which are sealed by ultrasonic welding. The geometric shape of the membranes can be octagonal or round, depending on the material and production series.

The Rokem Service company provides equipment maintenance: cleaning, washing of membrane filters. The practice of filtering tap water in St. Petersburg showed that in 12 years from the beginning of the first sale of these filters (more than 700 pieces), only after 7 - 10 years the first users of these devices needed the help of the company, which consisted in cleaning the membranes. The company restores the membranes in the filter within 24 hours, after which they can again work at full capacity. The water treatment plant for alcoholic beverages at the Liviz distillery has been operating on a similar principle with similar membranes since 1992. Only in 2003, the company carried out the first replacement of membranes in filter modules with new ones. This once again demonstrates the reliability of membrane operation on St. Petersburg tap water.

The filtration device is conveniently located under the kitchen sink, where there is always room for a clean water storage tank, connection of an ecological tap on the top plate of the table, connection of tap water inlets and outlets, and drainage of concentrate into the sewer. The simplicity and reliability of installation of the equipment allows the consumer to always have a supply of clean drinking water for cooking, in order to make delicious tea or coffee (and they turn out especially tasty with clean water). The company offers both a complete set for water purification, including all the necessary parts for a constant supply of drinking water, and a separate device for intermittent operation of the filter, consisting of a filter module without appropriate piping. You will not have to, as happens in most cases, constantly buy some parts and consumables for water treatment systems (for example, after 700-1000 hours of operation, new membrane modules, etc.). Our filters, and there are more than 700 of them in St. Petersburg alone, work long and reliably. The membranes last 7-10 years without replacement; the filters require minimal maintenance, are easy to use and bring joy and health to every home.

Water treatment systems ROCHEM

Filtration systems serve for the effective purification of artesian or tap water and the production of drinking water using ultrafiltration, nanofiltration and reverse osmosis membranes according to the highest international standards and with German quality.

ROCHEM Service Depending on the customer's requirements, the company supplies systems of any capacity, which can be located in small areas in kitchens or bathrooms. The systems are serviced by ROCHEM Service, St. Petersburg.

Low osmosis installation type LP-mini RONRO for purifying tap water and obtaining clean drinking water with a capacity of 30 to 60 liters per hour. Wall or floor option.

The company's water treatment systems are manufactured on a turnkey basis and supplied as proven, standardized systems of various capacities for apartments, houses, offices, restaurants, and bars. In addition to providing drinking water, you can equip systems that provide all the water needs of the entire house, including for baths, showers, swimming pools, dishwashers and washing machines. Depending on water needs, there are installations with different performance levels. Some of them are installed in kitchens or bathrooms, others, which provide water to the entire house, can be located in the basement. Installations can be semi- or fully automatic.

Modular FM technology
ROCHEM water purification plants are designed to remove all microorganisms and harmful products from tap, artesian, river, lake or brackish water. Only our company's installations are supplied with the NATO system for military submarines and surface vessels. But this organization does not buy bad attitudes. Our installations operate for more than 8-10 years without replacing filtration membranes. In saying this, we are based on the performance of some filtration systems operating at some enterprises in the city of St. Petersburg at this time. Office installations for home or office include low pressure reverse osmosis installation type RO 052 DT, shown in the photo. Low osmosis installation type LP-mini RONRO for purifying tap water and obtaining clean drinking water with a capacity of 30 to 60 liters per hour. Wall or floor option. With or without clean water storage tank. Clean water tap.

Installations for household use (apartments, offices, residential buildings)
Designed for the purification of tap or artesian water with a hardness of up to 1500 mg/l and a source water turbidity of no more than 3 NTU; for chlorinated water, activated carbon prefilters and a fibrous prefilter are used. Systems can be supplied with clean water storage tanks of various volumes. LP-NRO type installations are supplied with an external operating pressure pump; when the network pressure is above 3 bar, “Ball” type installations are used without external pressure pumps.

Microfiltration filters

Membrane and syringe filters produced by the Spanish company Albet, which celebrated its tenth anniversary in 2003, are designed specifically for microfiltration - retaining particles and microorganisms ranging in size from 0.025 microns to 10 microns.

Membrane filters are filters that retain particles on their surface, which means that there is no retention of particles on the internal fabric of the filter. Thanks to the uniform and homogeneous distribution of pores on the surface, it is easy to determine the maximum particle size that can pass through the filter, so that we can talk about the absolute level of filtration. These filters do not change the nature of the filtrate and almost do not adsorb the liquid inside them.

Syringe filters (filter membrane and holder made in a single housing) are disposable filter elements used for filtering small volumes of liquid (up to 100 ml) using syringes. An alternative option for filtering small volumes is to use detachable holders with replaceable membranes installed in them. The choice of filtration option (syringe filter or filter holder + membrane filter) in most cases depends on the nature and volume of the solution being filtered.

Purifying water from harmful impurities is important not only when using it as drinking water, but also for technical needs, where high mineralization leads to the appearance of scale, blockages in plumbing equipment and fittings, and incorrect operation of household electrical appliances. One of the effective ways to combat harmful components is a membrane filter for water purification, widely used in industrial production and households.

There are a number of membrane devices for water treatment on the market from different manufacturers; when choosing them, you should take into account the nature of the contaminants, the intended purpose of the purified water and the volume of its consumption. When independently installing systems using membrane filters, the degree of contamination plays an important role - if it is very intense, the use of pre-cleaning and softening filter devices is required. In order to properly assemble a water purification system using any type of filter, it is necessary to conduct a laboratory analysis of its chemical composition; this condition is mandatory when drawing water from wells and wells of private houses and country cottages.

A membrane water filter is classified as a deep cleaning device; thanks to the small pores of the filtration material, it is capable of filtering out contaminants with a diameter of 0.0001 microns. To understand what such a filter is, let’s consider the step-by-step technology of its production:

• The polypropylene mesh is cut into rectangles of the required length and width; it serves as a spacer between the layers of filter material.
• Pieces of polyester of the same size as the mesh are cut; it has tiny channels through which water passes and harmful impurities are retained; the material is the filter element of the membrane.
• Polyester is placed in stacks of 15 sheets and fastened together with high-frequency acoustic waves using ultrasonic welding technology, resulting in one of the assembly elements of the device - the filter.
• A roll of special filter paper is unwound and passed through a mixture of liquid plastic and solvent, which covers one side; after the plastic hardens and the solvent evaporates, a unique fine-mesh membrane structure is formed on the paper tape.
• The membrane is laid out on the table, covered on top with a mesh half the size, and the second part of the tape is folded up - you get a kind of envelope from two filtering surfaces, between which an insulating mesh is located.

• Glue is applied to the edges of a plastic tube with round holes along its entire length and a stack of polyester filters is applied to it, secured to the tube with tape.
• Place a membrane envelope with a mesh in the middle on the first sheet of polyester and glue it along the edges, put the next sheet of the filter on top, the membrane and glue it again.
• The operation is repeated several times (the number of filter membrane layers depends on the quality of the filter), resulting in a kind of membrane sandwich. In inexpensive household devices, the number of hoses wound around the drainage tube does not exceed one or two; in high-tech industrial installations, where high quality cleaning is required, the number of filter layers reaches 15.
• They begin to rotate the tube, winding all the filter elements assembled into a single whole around it, compress it on top and secure the filter layers with tape.
• Plastic end caps are installed along the edges and fixed with glue.
• A glass fiber glued thread is wound onto the cylindrical surface of the filter with the required tension, and excess glue is removed. After the adhesive dries, a durable fiberglass shell is formed on the surface of the filter.

During the production process, household filters are assembled from four sheets in the following sequence: membrane, supporting polyester filter, polyethylene backing, mesh. The sheets are folded together into one sleeve and wound onto a drainage pipe; there can be several of them in the filter, laid close to each other and twisted into a spiral.

Using the technology discussed above, the most popular rolled membranes are produced; membrane softeners in the form of disks or made from other materials (ceramics) are also found on the market.

Principle of operation

Rolled membrane-type water filters are most often used in household water treatment systems; their operating principle is based on passing liquid through a special fine-mesh membrane on an impregnated paper base and removing contaminants with partial capture by a polyester filter. It is necessary for the correct operation of the system - for the filter to function, water is supplied to the membrane under pressure, while the polyester layer creates resistance in the path of the water flow and prevents it from escaping through the purifier. In its absence, water under pressure freely passes through the filter in the longitudinal direction, without being forced into the membrane and then into the drainage pipe.

The operation of a membrane roll filter consists of the following sequence of technological operations:

• The purified water enters the end part of the filter and passes along the membrane; from this end, the internal plastic tube is sealed and does not have defragmentation.
• At the other end of the housing is closed by a cap with a small diameter outlet fitting that limits the pressure. As a result, excess pressure appears inside and the purified water is forced through a series of membrane filters to round holes on the central pipe.
• During the pressing process, all particles whose size exceeds the diameter of the membrane cells are collected in a polyester filter and between the mesh cells, and then washed out by a passing stream of water.

Important: If the filter system is not washed with running water, the small cells of the membrane become clogged with harmful impurities in a short time and it ceases to perform its functions.

• Thus, the filtered liquid moves simultaneously along the filter and in the radial direction, leaking into the membrane, twisted into a spiral. Purified water (permeate) is discharged outside through a central drainage pipe, and contaminated liquid (concentrate) with a high content of harmful impurities is collected at the outlet end of the filter after longitudinally passing through the mesh and polyester backing.
• The salt concentrate is discharged into a storage tank for further use in the household or disposed of by discharging into the sewer system.

As can be seen from the principle of operation of this filter, a significant part of the purified liquid (about 3/4) contains a high concentration of harmful impurities and is drained, therefore, when using such systems for domestic use, one should think about the rational use of these water volumes for economic purposes.

Tip: A good way out of the situation of high water consumption in apartments with metering devices is to insert a tee into the pipeline with a check valve, through which the contaminated solution is directed back into the water supply system. The filter is turned on during domestic water use (washing dishes, taking baths) and the concentrate is immediately consumed for household purposes.

Design of a membrane-based filter system

There are a large number of household membrane-type filter systems on sale from domestic manufacturers that have earned positive reviews from consumers, these include well-known brands: Aquaphor, Geyser, Istok, Novaya Voda, Atoll, Rosa. Typical reverse osmosis models consist of the following elements:

• Primary filter. Removes large mechanical particles from 5 microns in size, small grains of sand, suspended dirt, and rust from the water flow. The cartridge of this filter is often made of foamed polypropylene; it is used to mechanically purify water from suspended contaminants.
• Adsorption filter. The filter element of the purifier is activated carbon, the surface layer of which absorbs harmful substances from the water. Coal perfectly purifies water from chlorine compounds and organic impurities.
• High-quality after-treatment filter. The cartridge filler is briquetted activated carbon, which removes mechanical particles with a diameter of up to 1 micron from the liquid and performs additional purification of chlorine compounds and organics.
• Reverse osmosis membrane filter. Removes from water all particles ranging in size from 0.001 to 0.0001 microns or 96 - 98% of all contaminants; insoluble divalent metal oxides (manganese, potassium, iron), organic impurities, bacteria and viruses fall into this category.
• Mineralizer. Purified sterilized distilled water does not contain minerals and salts that are beneficial to human health, which were removed during the purification process along with harmful impurities. When used as drinking water, it is passed through a flow-through mineralizer with mineral salts, saturating the water, they increase its taste and make it healthy.
• Storage tank. Drinking water is sent to a metal storage tank for use at any time without waiting for the purification process to complete.
• Electronic control module (optional, needed for low water pressure in the water supply). It starts the pressure pump when the storage tank is empty and cleans the system automatically.

Classification of membranes by pore sizes

A membrane is a thin elastic film attached to a supporting surface around the perimeter; this definition is not very suitable for water treatment systems, where the purpose of membrane flexible plates is water filtration.

The pores of materials used in water treatment are capable of passing impurities of different diameters; taking this factor into account, a system has been developed for dividing membranes according to the size parameters of the particles being passed through into the following groups:

• Microfiltration (1-0.1 microns). Inclusions of this size are found in turbid water and gray wastewater; similar filters are also used to purify water from large colloidal particles and coarse organic impurities. Filters of such cleaning are classified as mechanical; in household pre-water treatment systems, similar functions are performed by a polypropylene cartridge.
• Ultrafiltration (0.1-0.01 microns). Small colloidal impurities and high molecular weight compounds, algae, bacteria, and trivalent insoluble metal oxides are screened out.
• Nanofiltration (0.01-0.001 microns). Used in water softening systems, they are capable of purifying liquid from soluble divalent oxides of iron, potassium, manganese, chlorine, and various types of dyes.
• Reverse osmosis (0.001-0.0001 microns). Deep cleaning filters with efficiency up to 99% are widely used in industrial desalination of sea water. All salts and metal oxides, bacteria, petroleum products, dyes, and pesticides are removed from the liquid. Reverse osmosis systems are widely used in medicine, food and chemical industries to produce sterilized water.

When choosing a water treatment plant, an important criterion is the pressure in the system; for large pore sizes in membranes, 1 - 2 atmospheres are sufficient; the highest pressure is required for reverse osmosis filters - at least 3 atmospheres.

Types of membrane filters by design

In addition to dimensional parameters, membrane filters, depending on their design, are divided into the following types:

Disk. This type of filter is rarely used in households; microporous membranes are more often used in the industrial sector for water purification of large volumes of water in large-sized installations. The materials used to make them are nylon, polyamide, polyethersulfone, fluoroplastic, polyethylene terephthalate (lavsan), cellulose acetate. During the production process, cleaning elements with membranes are placed in filters in the following ways:

• substrateless, the filter is made of homogeneous material;
• reinforced with a fabric or polymer mesh base;
• epigastric - with a base made of durable large-porous material.

On the water treatment equipment market, you can purchase disk Geysers made of polymer materials with built-in grooves that allow particles with a size of 100 microns to pass through.

Tubular. They have a simple design in the form of a tube made of porous material, into which the filtered liquid enters through an end cap with holes and is then squeezed out under pressure, passing through the pores of the membrane purifier. The materials for manufacturing the body of a fine-porous membrane can be ceramics, cermets, plastics, and alloys of various metals.

Rolled. The design of such filters was discussed above; they are a sandwich of reverse osmosis film, polyester backing, polyethylene film and mesh wound around a drainage tube. During their operation, water from the end part enters the membrane and flows in a spiral into the drainage holes, and the concentrate with impurities is disposed of or used for household needs.

Hollow fiber. This type of membrane is designed for industrial use; it consists of very small filtration tubes folded into a bundle. The liquid to be purified passes through capillaries in their walls, the diameter of which prevents the passage of larger impurities. Ultrafiltration membranes have a similar design, screening out particles with a diameter of 0.1 microns.

Track-membrane. Membranes of this type are made from thin film polymers with a thickness of 12 - 23 microns by bombarding the surface with krypton ions, resulting in through channels with a fixed diameter of up to 0.05 microns (for polyethylene terephthalate film). One of the simplest devices based on them, used for water purification in households, is a film membrane with a hole diameter of 0.2 - 0.4 microns, placed in a closed plastic case.

To operate the device, its body is immersed in a container of water and a drain tube is connected, lowering it below the liquid level into a reservoir (jar) to collect filtered water. Before filtering, the water is sucked in and after the jet mode switches to drip mode (the membrane filter is put into operation), the filtrate begins to be collected.

Track membrane filters for fine water purification, the average price of which is about 700 rubles, do not require electricity, the device can be taken with you to the country, on a wild vacation, or on a camping trip. The advantage of the track system is ease of maintenance - after the pores are clogged, the traveling membrane filter for water purification is disassembled, the purifier is removed, wiped with a clean sponge to remove plaque under running water and immersed in a solution of 5% citric acid to restore it.

A wide range of track filters are sold on the water purification equipment market, popular brands are Nerox, Kapel, Snezhinka.

Pros and cons of membrane filters

Among all the varieties of membrane filters, reverse osmosis units with an initial cost of about 6,000 rubles, which have the highest water treatment efficiency, have been used in households. Their positive qualities include:

• High purity of filtered water, which is free of all types of bacteria, microbes, viruses, and metal oxides that cause scale.
• The filtration system has a simple design and can be independently serviced by the consumer.
• Unlike popular household alternative cleaning methods with aeration units and ion exchange resins, a reverse osmosis system takes up little space under the sink.
• The service life of the membrane filter, thanks to the technology of constantly cleaning its surface with running water, exceeds the time of using cartridges in jug-type systems and can reach up to 2 years. Systems that provide automatic membrane cleaning operate without changing the filter for 5 years or more.

Despite the highest quality of cleaning, a reverse osmosis membrane filter has a number of disadvantages that limit its widespread use in everyday life:

• When operating installations with this filtration method, only 1/4 of the incoming water is effectively purified; the rest will have to be drained into the sewer or used for economic purposes.
• High quality cleaning requires strong pressure in the system of up to 10 atmospheres to force water through a fine-mesh membrane; such pressure can only be achieved using an electric pump, which requires electricity to operate - this significantly increases operating costs.
• For the reverse osmosis membrane to work correctly, the water must undergo preliminary purification before filtration - as a result, three additional filters are used (standard set Aquaphor trio, Rosa). In two of them, carbon cartridges must be periodically replaced, which leads to additional costs.

• Passing through a reverse osmosis system, water loses minerals beneficial to human health and becomes tasteless, therefore, to improve taste, an additional mineralization unit with consumable components is used.
• Compared to other systems, the reverse osmosis filter has a rather low performance (maximum 0.12 l/min for the popular Geyser Prestige model) and is used only for drinking water.
• Many users complain about the noisy operation of the automatic system, which turns on the electric pump pumping water after the storage tank is empty; sometimes the electronics get confused in operation and constantly turn the pump on and off.
• The average cost of a reverse osmosis filter is about 7,500 rubles. without a pressure pump - not everyone can afford such expenses.

How to clean a reverse osmosis filter

The need and frequency of cleaning a reverse osmosis unit depends on the quality of water, filtration volumes and pressure in the system; if there is an automatic system with a built-in water treatment function, the life of the cartridge can be up to 6 years.

If the installation design does not provide for automatic filter maintenance, you can wash it yourself using one of the following methods:

• Take out the cartridge and direct a stream of water into it in the opposite direction; due to the slight pressure, it will pass right through the filter layers, washing away deposits. After washing, the filter can be placed in water with citric acid for several hours.
• Modern designs of household filters are distinguished by their low strength housing, which consists of several layers of polymer film. It is quite simple to unwind it, then straighten the 2 spiral arms, in which it is easy to separate the filter, mesh and substrate from each other. You can lower the entire system into a container of water and thoroughly rinse its components with further settling in a solution of 5% citric acid. After drying, the cartridge can be easily reassembled by securing the body with tape or tape.

In households, to obtain high-quality drinking water, a membrane water purifier with reverse osmosis has proven itself to be excellent, producing 95 - 98% filtration of all components harmful and beneficial to the human body. Despite a lot of shortcomings (low productivity with utilization of 3/4 of the water volume, high operating costs, lack of useful minerals), the system has no competitors in terms of filtration quality and is the best for obtaining ultra-pure drinking water from municipal mains and individual water sources.

Video

Operating principle of a reverse osmosis system

How a roll membrane filters water and its design

Track membrane filter - how to use

Reverse osmosis

Water purification by reverse osmosis

Reverse osmosis units provide the ability to purify water simultaneously from soluble inorganic (ionic) and organic contaminants, high molecular weight compounds, suspended solids, viruses, bacteria and other harmful impurities. Since the filtrate flow is directly proportional to the surface area of ​​the membrane and inversely proportional to its thickness, when designing reverse osmosis units, membranes with the maximum possible area and minimum possible thickness per unit volume of the apparatus should be selected.

Reliability of installations reverse osmosis increase due to the installation of backup equipment, with the possibility of its multifunctional use, optimization of the number of membrane elements in each section of the device, as well as increasing the reliability of filter elements and equipping with a computer system for searching for failed membrane elements and modules.

As a rule, reverse osmosis is used in technological processes for the desalination of sea and brackish water, the production of ultrapure water for the pharmaceutical, radio-electronic and instrument-making industries, as well as in the creation of recycling water supply systems for enterprises (membrane concentration of wash water and desalination of purified wastewater in galvanic production and production of printed circuit boards). Abroad, membrane reverse osmosis units are most widely used in industry: Dow Chemical "Filmtec", GE Osmonics, Toray, Norit, Inge, Hydranautics, etc. In Russia, for the assembly of reverse osmosis units (Technopark RKhTU named after D.I. Mendeleev, Federal State Unitary Enterprise " Research Center named after M.V. Keldysh"), both rolled and hollow fiber elements from the manufacturers listed above, as well as domestic reverse osmosis cellulose acetate (AC) and polyamide (PA) polymer membranes produced by the Vladipor Research and Development Center are widely used.

Characteristics of reverse osmosis roll elements

Application of reverse pox plants for wastewater treatment of galvanic production

The technology for treating galvanic wastewater using a combination of electroflotation, microfiltration (ultrafiltration) and reverse osmosis is presented below. At the first stage, dispersed substances are extracted in an electroflotator; at the second stage, micro-ultrafiltration fine purification of water is performed before supplying it to a reverse osmosis installation for desalting at the third stage Fig. 1. Removing heavy metals, organic compounds and soluble salts from water makes it possible to obtain purified water of very high quality, which can be used for circulating water supply in a closed cycle.

The water that millions of people drink every day contains a huge amount of a wide variety of harmful impurities, substances and bacteria. Many people are sure that all these substances can be neutralized by boiling. This opinion is wrong. Experts rightly claim that boiling cannot remove everything from water. The stakes are high - everything in the water can cause serious illness and cause irreparable damage to health.

In order to save their body, many people install membrane water filters, which, according to manufacturers, are capable of maximally purifying water of any quality.

Thus, these systems can remove a variety of bacteria, harmful suspensions, and impurities from it, and even at the same time maintaining the structure and its salt balance unchanged.

What is a membrane?

One of the main properties of almost all water is the retention of various harmful substances, impurities and their compounds.

Membrane filters perform these tasks using a thin film of synthetic materials. It has special pores through which only oxygen and water pass. Everything else, which is a mass of various organic and inorganic substances, remains on the surface. To produce such membranes, polyurethane, cellulose, acetate and lavsan are used, but there are other materials that have similar properties.

Types of cleaning systems

Membrane-type filters are not a new technology. Their history begins in the 19th century. Then the first filters were made on the basis of fiber, however, for some reason this system was never able to gain the proper distribution. It was only in the 60s of the last century that engineers developed a new membrane. This is a prototype of what is used today.

The differences between such membranes lie in the pore sizes, as well as in the design.

For example, smaller hole sizes will result in higher pressure inside the filter. Several stages, each of which will purify water from various pollutants, will significantly improve the quality of drinking water. However, the price rises.

Microfiltration membrane

In this type of system, the microscopic hole sizes can vary from 0.1 to 1.0 microns. These products are used in first level cleaning devices. They are from those compounds that make the water cloudy. This type of filter membrane is nothing more than a preparatory level. Only after this can you move on to finer cleaning. This solution is often used when wastewater needs to be treated.

Ultrafiltration

The ultrafiltration membrane can have pores whose size ranges from 0.02 to 0.1 microns.

At this stage, all and various high-molecular substances are removed from the water. In addition, this filter copes well with bacterial contaminants. The only caveat is that this product is not able to remove salts. Often these solutions are used in industrial-scale wastewater treatment plants. They can also be found in household filters, where salt content in the water is allowed.

Nanofiltration

Nanofiltration membranes have pores from 0.001 to 0.02 microns. These elements are responsible for softening very hard water. This membrane can retain organochlorines and heavy metal particles in its pores. If we talk about the level of removal of heavy metals as a percentage, then the system is capable of retaining only 30%. But at the same time, this nanofiltration part almost completely allows dissolved salts to pass through.

Reverse osmosis membrane

The pores in it have the smallest sizes - they can range from 0.0001 to 0.001 microns.

The product has high selective properties and is created in such a way as to remove almost all contaminants, impurities, and harmful substances that people consume with water.

This membrane is capable of permeating gases and small amounts of salts. If you need to filter sea water, then a water filtration system with these elements allows you to desalinate it by 97%. The cleaning process using these membranes leads to the fact that salts, viruses, various bacteria, petroleum products and much more are almost completely neutralized.

Filters are made from real, high-quality and harmless water, which is then bottled, used to prepare a wide variety of drinks, and used in pharmaceutical and other industries. It is also widely used in electronics and microbiology. This technology is very effective. However, the prices for such elements are quite high.

Operating principle

So, these filters are a very thin membrane with a huge number of pores of various sizes. These elements are capable of providing the maximum level of cleaning. In addition, after water has passed through membrane filters, it does not change its composition. Both salts and microelements important for humans remain in it.

In the process of filtration with membranes, water has a high level of purification, and is also complete, saturated with all necessary minerals.

In these and similar systems using membranes, the tangential principle of fluid movement around the membrane works. Water enters the filter through one channel and leaves through two. It follows that water accumulates on both sides of the membrane.

The efficiency of these filters generally depends on the area and thickness of a particular membrane. Water pressure and temperature also significantly affect performance.

Hiking filters: operating principle

For hiking enthusiasts, there are popular Nerox elements, the operating principle of which is significantly different from stationary installations. So, membrane filters are placed in a container containing dirty water. Clean water will be discharged into another container through a special channel.

These filters are quite effective and allow you to clean the liquid as much as possible. But they have one serious drawback. It is necessary to periodically clean the membrane from sediment. Manufacturers claim that the system should be cleaned manually.

How and with what to treat the membrane

If the sediment is inorganic, it is easier to remove it with products that contain acid. Organic substances, their compounds, and biomass are easily washed out with alkali-based solutions. You should not use nitric or sulfuric acid for cleaning.

With their help, you can easily disable an expensive membrane element.

Advantages and disadvantages

Among the advantages that this water filtration system has are the simplicity, ease of operation and maintenance of the membrane. In addition, the liquid after all stages of purification is very clean, but at the same time its salt composition is retained. The membrane is capable of removing even the smallest impurities. Most systems are quite compact in size. Some models can be successfully used in field conditions, as well as wastewater treatment systems. Disadvantages - high price. In addition, they note that despite all the efficiency of the work, the speed of this process is incredibly low. Installation of storage tanks will be required.

Types of systems by design

So, if we talk about design, there are several types of membrane filters. These are models based on a single substance, without substrates. There are also membranes based on fabric or made from various porous materials. These are reinforced type elements. They also produce products from raw materials with large pores.

Reverse osmosis filters

Disc-type reverse osmosis membranes in most cases are thin elements based on composite materials. Each layer of such a filter is made of a variety of compounds.

Tubular

Systems of this type are made of porous materials. It can be plastic, ceramics, metal or metal ceramics. As for the dimensions, the diameter of such a membrane in different models can be up to several centimeters.

In addition, we can distinguish asymmetric and symmetrical tubular membranes. In the former, the density of pores throughout the entire volume is the same. In the second case, one of the surfaces can be made of a denser material. This is the working layer that reports the degree of cleaning. Large-porous membranes only allow purified water to pass through.

Roll filters

This is a system where a membrane is installed on a drainage hose. When the water flow begins, the liquid moves in a spiral. After this, its entire volume accumulates in a special hose and is discharged from its second end.

The design has a convenient shape, and the working part is ultra-thin. This is a guarantee of high performance. The risk of contamination is also significantly reduced. These solutions can be used for a variety of purposes, including wastewater filtration.

Hollow fiber

Hollow fiber membrane filters can also be distinguished. They are shaped like tubes. A certain amount fits in the filter device. The result is a solution where the working surface is significantly increased, which has the best effect on productivity.

The disadvantage is virtually no control of flows along the filter fibers.

These models often get clogged. Because of this feature, they should not be used for wastewater treatment.

Prices

Manufacturers set different prices for equipment. In most cases, the cost depends on the performance and degree of purification. Let's look at the most popular models from different manufacturers and their prices.

Nerox - 1350 rubles

These products are suitable for filtering wastewater. The osmosis filter allows you to maintain the salt balance. The product is lightweight and compact. This model can be used both permanently and outdoors. In order for the system to work properly, it is necessary to periodically clean the membrane.

"Aqua-expert" - 1450 rubles

This model is designed to work with water of any quality. You can also apply the filter to wastewater. According to the manufacturer, the membrane allows you to restore the structure of the liquid. The system is very easy to use and clean if necessary.

Solutions from the company "Aquaphor"

Reverse osmosis "Aquaphor" is a productive, compact home system for drinking water purification. The series of these filters differed from conventional systems in that they had a pleasant design.

The system has a special design. Thus, the model consists of a collector and a replaceable cartridge. Unlike traditional reverse osmosis purification systems, this filter is much easier to maintain and operate.

The manufacturer claims a high resource of replaceable cartridges. These models are also easy to replace filters. To do this, just press a button, remove the cartridge and insert a new one. Reverse osmosis "Aquaphor" does not require constant disinfection: when replacing the cartridge, almost all surfaces on which bacteria could settle will be perfectly clean. Purified water after these filters will contain only oxygen. All other impurities will be eliminated. The filtration quality is very high.

Filters from the company "Ecosoft"

The Ukrainian manufacturer Ecosoft produces household systems under the Our Water brand. Product lines include jug, flow, and reverse osmosis systems. Today this company is quite successful, and its products are in demand and receive positive reviews.

Unique technologies developed by scientists from Ukraine make it possible to effectively purify water from almost all impurities known today. The osmosis filter is able to cope with iron, manganese, organic compounds, and heavy metals. The company's ready-made solutions are in great demand. These systems really make the water high quality and clean.

The cost of Our Water solutions is quite high. However, this is not just a filter. This is a whole set of equipment that is designed to make the lives of most people better. All necessary equipment is included. The company also produces replacement filters for the entire product line. All those who care about their health should definitely purchase such systems. Water is life, and clean water is a healthy and happy life.