Types of water filters and their operating principles. Water filtration for the home: dispelling myths Classification of water purification stages

The water coming from the local water supply does not meet high quality and purity. The causes of pollution and its poor quality are the sharp deterioration of the ecological situation on the planet. As a rule, untreated water can not only spoil the taste and color of the prepared dish, but also negatively affect the health of the entire body as a whole. In this article we will talk about what methods of water purification exist, what systems are used, and also provide a comparative description of the types of water treatment.

According to studies, it was found that most of the water reserves on the planet are not suitable for human consumption. The problem of pollution is related to the growth of industry and production. Residents of many apartment and private houses use a central water supply, and all liquid entering the taps goes through several stages of filtration and purification. Most people can definitely say that the water quality is poor, which is why it is quite common to see water filters in the kitchen. Modern water purification systems allow you to get rid of various types of contaminants. For example, water purification technology in the system can eliminate chlorine, rust, and heavy metals. It is worth noting that companies producing household appliances recommend installing water treatment systems for technical purposes. In recent years, household appliances cannot withstand the poor quality of the central water supply. Breakdown of household appliances occurs due to the presence of impurities in the water, which negatively affect the operation of the mechanisms.

Classification of water purification stages

Methods and means of water purification can be roughly divided into the following groups:

physical;
chemical;
physico-chemical;
biological.

All methods of water purification consist of various step-by-step filtration processes and have a variety of hardware systems. Modern cleaning methods are a set of measures consisting of certain tasks, the main goal of which is a high-quality filtration process. Water purification systems operating on the same principle are most often used where water is contaminated with one or more substances. Let's look at each type of cleaning in more detail:

The physical method of water purification is used to treat large quantities of water and remove large debris. The main functions of the physical method include processes such as:
- strain or pass a stream of water through special grates to collect large debris: this method is considered the initial stage of cleaning;
- defend: this stage is characterized by the separation of mechanical contaminants using gravitational forces, which contribute to the fact that the debris settles at the bottom of the tank;
- filter: this process consists in the fact that the entire liquid flow passes through a special porous base of the filter material, where various particles of debris are retained;
- treat with ultraviolet light: this process is actively used for water treatment, i.e. Treat already purified water with ultraviolet light.

Chemical methods of water purification work through the interaction of reagents and pollutants, which subsequently decompose. This method includes processes such as:
- Implementation of neutralization, where the acid-base balance is equalized, through the interaction of various alkalis and acids;
- Chlorination or treatment with chlorine-containing agents, this stage is performed for an antibactericidal effect. Chlorination involves the oxidation and reduction of water, the main purpose of which is to completely neutralize the liquid from toxic substances.

Physico-chemical methods of water purification are used to remove various pollutants. This method is successfully used during pre-cleaning and at the deep cleaning stage. This method is most often used for processing, disinfecting and purifying wastewater in apartment buildings and private buildings. It is worth noting that the physicochemical method includes the largest number of different processes.
The biological method is used using living bacteria that are capable of cleaning water bodies from nitrates, chemicals, phosphates and phosphorus particles.

Filter characteristics

Modern water purification technologies offer a large selection of filters for water purification. Each product has the same purpose, but their differences are:

form;
power;
principle of operation of the entire structure.

The modern market offers a large selection of systems that allow not only to purify water, but also to soften it. Main types of cleaning systems:

Mechanical scheme of water purification. The essence of the work is to retain large and insoluble impurities (sand, clay, rust). The mechanical method includes two types of devices that increase the efficiency of liquid processing. The first device is mesh parts built inside the body of the product; they are a regular mesh that traps small particles. As a rule, it can be washed and used further, or a replacement part can be installed. The second device is replaceable cassette cartridges or multilayer filters. During operation, dirt and insoluble particles settle on the walls of the cartridges and must be replaced within a certain period of time. The photo shows models of coarse water purification systems

The reverse osmosis system is considered a powerful and effective filter, during the operation of which 5-6 stages of water purification are involved. Liquid treatment is performed by passing water through a special membrane that is the same size as water molecules. Osmosis removes absolutely all impurities, contaminants, small and large particles of debris from water, and also neutralizes bad microflora. The system is installed under the sink, where all the cassettes of the product are neatly placed, and at the top of the sink there is a small tap from which purified water will flow. The photo shows a reverse osmosis system.

For information! The cleanable filter is complemented by a special mineralizer part or ultraviolet blocks, which enrich the water with all the necessary beneficial salt components.

Carbon water purification schemes or flow systems are effective in water purification; thanks to their sorbent, they are able to remove all organic impurities, chlorine, unpleasant taste, odor, plaque and color. Coal cassettes are used for wastewater purification, water treatment and in everyday life. They are mounted both under the sink and integrated into the general water supply system; the cassettes are changed once every 3 months. The basic rule in the operation of coal systems is the organization of normal pressure, usually at least 8 atmospheres, the room must also have proper ventilation, and the humidity level must not be lower than 70%.

Advantages and disadvantages of modern filtration systems

Advantages of flow systems:

easy to install;
have a separate tap for the outlet of clean liquid;
compact;
effectively purify water from chlorine, impurities, rust, toxic metals and unpleasant odors, colors, plaque and other substances harmful to the human body;

Disadvantages of flow filters:

carbon cartridges are not capable of neutralizing the removal of mercury from water;
due to the settling of small particles on the surface of the cassette, bacteria and microbes can form;

Advantages of a reverse osmosis system:

thanks to the porous membrane, the installation is able to neutralize all small particles of debris;
the liquid is perfectly cleaned;
The internal mesh does not accumulate debris, which eliminates the formation and proliferation of bacteria and microbes.

Disadvantages of the osmosis system:

high installation cost, price varies between $400.

Advantages of tabletop jugs:

affordable price;
there is no need for mounting and cutting into the central water supply system;
ease of use.

Disadvantages of jugs:

frequent replacement of cassettes;
slow cleaning;
is not able to remove all contaminants from water.

Of all the water purification filter systems presented, the most effective is the reverse osmosis system. Thanks to its reverse osmosis filter system, it duplicates the work of the cell membrane, which allows only water molecules and oxygen to pass through; all other particles remain in special waste compartments. This treatment process allows you to purify water at the molecular level, and most importantly, increase the quality of water without losing essential microelements.

Today, there are different ways to filter water. Let's look at some of them.

This method is considered the simplest. With the mechanical filtration method, water passes through a mesh or sieve. Mechanical filtration is widely used in water treatment plants.

This method involves the sorption of charged ions; after one ion is absorbed, another ion enters the solution; it is this ion that is contained in the sorbent. The ion that must be removed from the liquid stops on the sorbent. This is how the so-called “harmful” ions are replaced by other “harmless ions”.

Sorbents that work on this principle are usually called ion exchangers or ion exchange materials.

Ion exchangers have the ability to remove one type of dissolved salts from water (for example, magnesium salts, calcium salts) and replace them with others (for example, sodium salts).

Basically, ion exchange is used to remove nitrates and heavy metal cations from liquids, which can cause irreparable harm to human health.

A water ionizer softens hard water by removing magnesium and calcium from it.

Electrochemical filtration

This method is based on oxidation and reduction reactions. They occur in water when it is exposed to a strong electric current. As a result of this process, “living water” and “dead water” are formed.

This method is quite cheap. It is beneficial to use, since you can get high productivity at low costs.

Electrochemical filtration systems are used primarily for industrial purification and not for drinking water filtration.

Using this type of purification, you can get rid of all microorganisms in the water. But the downside is that along with microorganisms, some organic substances are also destroyed.

In addition, no one can know the exact composition of the original water, so it is unknown how it is affected by a strong electric current and what the reaction of the substances in the water will be. Such reactions may ultimately render the compounds completely unusable.

Sorption and sorption filters

Sorption is the process of absorption of impurities from a gas or liquid by solid substances, the name of which is sorbents.

A liquid or gas is passed through a sorption filter (a vessel filled with a sorbent). Thus, sorption purification occurs. The most important thing is to choose the right sorbent and cleaning mode; in this case, you can achieve a good result and remove all harmful impurities from the gas or liquid. The operation of filter systems for water and gas masks is based on this principle.

Most often, activated carbon is used as a sorbent. It is produced in huge quantities every year and is capable of removing impurities of various origins from water.

But there is also such a sorbent of natural origin as zeolite. It is a fairly strong sorbent. Zeolite purifies water from various chemical compounds, viruses, pathogenic microorganisms, nitrates, radioactive elements and so on. In addition, zeolite has the ability to enrich water with potassium and magnesium.

Physico-chemical cleaning method. It is used to clean sewers from colloidal impurities, fine particles, and dissolved impurities. Recently, water purification tablets have become popular. Such tablets include the following - aquasept, clorsept, pantocid, aquatabs, hydrochlorazone. With one such tablet you can disinfect 0.5-0.7 liters of water in 20-25 minutes. If the water is heavily polluted, the dose is doubled.

Sodium hypochlorite is also used to disinfect water. This substance has been used for a very long time; it destroys various microorganisms. The most effective method of disinfection is the use of sodium hypochlorite, which is obtained by electrolysis of two to four percent solutions of sodium chloride.

The bactericidal effect of sodium hypochlorite can be compared with the effect of dissolved chlorine.

This method involves filtering water using a reverse osmosis membrane. Water is passed through the membrane, which is a kind of sieve, and all the impurities that are dissolved in it are retained.

Such systems result in highly purified water, which is very close to distilled water in quality. This method can even purify liquid from chlorine and sodium ions.

Reverse osmosis devices must contain activated carbon, because the membrane cannot retain bacteria and highly volatile organic substances.

Disadvantages of reverse osmosis filtration:

The cost of such installations is quite high, so not everyone can afford to purchase it.
The productivity of reverse osmosis units is low; they can purify 20-25 liters of water per day.
Before purifying water using this method, it is necessary to carry out mechanical purification of the liquid.
In addition to harmful impurities and substances, all necessary substances are removed from the water, so it does not contain the microelements that the body needs. After filtering, they need to be added.
After filtration, only 25-35% of water is obtained.

Distillation

This method is not used often. Distillation is the purification of water by evaporation and further condensation of steam.

In this way, it is possible to separate the liquid from the solids contained in it. Distillation systems must contain activated carbon.

Many people are interested in how to choose a water purification system? But to answer this question you need to know what you will have to cleanse it from. For this purpose, bacteriological and chemical analyzes are initially carried out.

Ways to make water drinkable: Video

It is generally accepted that water from deep wells is fresh, clean and tasty. However, it is not. Water from autonomous sources must often be passed through multi-stage purification systems, as it does not comply with sanitary rules and regulations. Not only natural factors are to blame, but also man-made impacts, as well as non-compliance with construction and operational rules.

Well water contains sulfur bacteria, which are not afraid of a depth of 50 meters. Thanks to them, the water smells of hydrogen sulfide. Deep waters are very rich in minerals, as they are constantly in contact with various rocks.

Deviation of water quality indicators from the norm may not be visually noticeable. But this does not mean crystal purity. The water must be tested in laboratory conditions. Based on the test results, the necessary water filtration system is selected.

Well water analysis

How to properly collect water for analysis

The result of the analysis directly depends on the correct sampling. It is not enough to pour water from a tap or water pipe into a bottle. Sometimes a sanitary and epidemiological station employee may ask about the method of collecting water. If it was assembled incorrectly, the owner of the well will be sent back with the necessary recommendations. It may turn out that a water sample will be accepted without questioning and analyzed. Naturally, it will be irrelevant and you will have to deal with imaginary problems.

There are certain principles of water intake:

You should use only glass or plastic containers, but never metal ones.
You can use used mineral water bottles. The containers should not be used after drinks, as they contained persistent dyes that cannot be washed off with hot water.
The maximum volume is up to 1.5 liters.
A plastic bottle is doused with hot water, and a glass bottle is doused with boiling water. Next, you should wash the bottle a couple of times with tap water from which the sample will be taken. Do not use any cleaners, including baking soda.
Before drawing water, it is necessary to drain the water for 20 minutes to prevent stagnation and the ingress of metallic substances from the pipes.
To reduce the concentration of oxygen, which causes chemical reactions, it is necessary to draw water from a thin stream.
The container must be filled completely so that the water flows out when closing the lid. This eliminates additional air supply.
The bottle must be wrapped in light-proof fabric or paper.
The test must be taken within 3 hours. If this is not possible, then storing water in the refrigerator for up to 2 days is allowed.

It is mandatory to submit water for analysis when opening a well, and then once every 2 years. If the water becomes cloudy or has some kind of aftertaste, you should immediately take a sample of the water to the sanitary and epidemiological station. Poisoning can be caused by industrial emissions or wastewater.

Signs of poor quality water

Poor quality water can often be identified by external signs. At the first suspicion, you should avoid drinking raw water. A visual inspection will help identify the culprits and eliminate them:

The smell of rotten eggs - hydrogen sulfide, which is very dangerous for the body, has entered the water.
The water turned slightly yellow, and a rust coating formed on the sink - a high concentration of iron. Water must be boiled before use.
A sediment forms at the bottom of the dish - the mesh filter is clogged or the walls of the well are covered with silt. It is possible that gravel will be washed away from the fill.

Methods for purifying water from wells

Today there are many different schemes that can be combined or used alone.

Mechanical water purification is mandatory for any water intake.

Thanks to mechanical cleaning systems soil particles and organic matter are removed, eliminating the possibility of clogging of plumbing equipment and subsequent filters.

At the first stage, submersible pumps are used for wells, which are not enough for complete cleaning. Additionally, filters for mechanical cleaning should be installed.

Aeration is the process of enriching water with oxygen to activate oxidative reactions.

Thanks to this from the water ferrous iron is removed, which becomes insoluble and is easily filtered later. With the help of this technology there is oxidation of hydrogen sulfide and heavy metal ions.

Magnetic processing appeared quite recently and softens water. Dissolved salts crystallize in water and are then filtered.

Reagent methods used in extreme cases when other methods of neutralization are ineffective.

Reagent-free cleaning involves filling with synthetic or natural components. With its help, various problems are solved. The components act as a catalyst for oxidation reactions and as a sorption material.

Ion exchange technologies are based on the use of certain resins for the demineralization of water.

Water without impurities and completely safe for drinking can be obtained after reverse osmosis. The liquid is passed through membranes that allow only water molecules to pass through.

The choice of an effective well water purification system depends on the composition of the water.

Modern filtration of water from a well

Filtration of water from a well will allow all family members to use safe water, extend the life of heating and household appliances, prevent clogging of plumbing equipment, etc.

As written above, the number and types of cleaning elements are selected individually and depend on the initial degree of contamination.

The standard option is: a mechanical coarse filter, fine filters, chemical and biological filters. However, not everything is so simple: filters require a lot of space, have different input parameters and energy consumption, and it is necessary to coordinate technological parameters.

An ideal option for a private house that takes water from a well is to use complex modular systems.

They represent the required number of modules, which are matched in all respects and installed in the required sequence. Often, owners of private houses additionally install pumps to ensure good water pressure.

Types of filters for purifying water from a well

The following types of filters are used to purify water:

Mineral - mesh cylinders filled with mineralized substances. Remove salts and chemical compounds from water. Filters with different bandwidths are used.
Woven - cylinders that are wrapped with rope or fabric. Retains metal oxides, crystallized salts and chemical additives.
Fine cleaning has two holes at different levels. The filter body consists of activated carbon or silver ions.
Reverse osmosis – universal filters. Oxygen-containing molecules pass through the nanomembrane. Purification degree – 99.9%.
Filters based on ultraviolet radiation, which has a detrimental effect on many microorganisms. No reagents are used, and the water becomes softer.
Ozonating filters remove germs and viruses.
Aerators remove hydrogen sulfide, manganese and iron. The oxygen concentration in the water increases.

A comprehensive treatment station is purchased once and solves all problems with the quality of drinking water from a well. The cost of the equipment is quite high, but after a couple of years of operation it will completely pay for itself.

In some countries, such as India, drinking tap water is dangerous and can cause stomach upset or intestinal infections. In Russia, things are better with water supply, but many still use a filter. Why is it necessary and which device is more effective?

In large Russian cities, water supply stations guarantee the safety of tap water. But before it gets into our tap, the liquid goes through pipes. Many pipes are old, rusty and worn out. Through them, harmful substances enter the tap water.

Some people don’t drink tap water because they smell a suspicious taste in it. But even if the water tastes normal, it doesn’t mean it’s safe. To check whether it contains impurities and contaminants, contact the sanitary and epidemiological service and submit a sample of the liquid there for testing.

You can roughly determine the water quality yourself:

If scale appears in your kettle, white stains remain after washing the dishes, and after brewing tea a film appears in the mug - the water is hard, that is, it contains a lot of salts.
A putrid taste of water indicates the presence of hydrogen sulfide, and a tart taste indicates an excess of iron.
If your clothes have a gray tint after washing, it means there is manganese and heavy metals in the water.

In addition, you can take a look at the Internet project of Rospotrebnadzor “Russian Water Map”. The website has a map of laboratory water tests in different regions. Most of the research is in the Moscow region.

Some people prefer bottled tap water from the store, but this also has its own nuances. According to experts, bottled water does not always meet safety requirements. A list of “unsafe” brands is available on the Roskontrol website. In addition, water from the store is usually more expensive than filtered water at home. That's why many people start buying filters.

The filter improves the quality of the liquid: it cleans it of heavy metals, impurities, viruses and bacteria. The worse the water, the more powerful and expensive the device is needed. We reviewed the types of water filters and at the end of the article we provided recommendations for their selection.

Rough or mechanical cleaning- from large solid particles of sand, rust, clay, etc. Coarse filters are meshes made of steel or polymer materials with small cells.

Filters fine cleaning use the following technologies:

Sorption purification– from chlorine, petroleum products and other harmful compounds. During cleaning, water passes through a sorbent - as a rule, it is activated carbon.
Ion exchange– water passes through ion exchange resins. As a result, magnesium and calcium ions, which give water hardness, are replaced by harmless sodium atoms.
Reverse osmosis– the most effective cleaning technology. Under pressure, water passes through a membrane that allows almost nothing to pass through except the liquid itself.
Ultraviolet disinfection– eliminates most microorganisms. In urban water supply centers, water is already treated with ultraviolet light, so it is more likely to be used for water supply from a well or borehole.

Types of filters for water purification in an apartment

The most popular kitchen filter for drinking water. The device consists of three parts:

Jug made of glass or plastic. Capacity volume – 1.5–4 liters.
Receiving bowl, or the funnel takes up almost half of the jug. A cleaning cartridge is attached to its bottom.
Cartridge purifies water. It needs to be replaced periodically: depending on the model, it is designed for 100–450 liters. There are cartridges with and without threads. The latter can be installed incorrectly, then untreated water will leak into the tank.

The liquid flows through several cleaning layers inside the cartridge:

prefilter traps solid insoluble particles;
Activated carbon removes most harmful organic compounds. Typically, this is the main filter component;
ion exchange resins soften water and remove heavy metal impurities;
silver iodide kills bacteria;
postfilter blocks particles of filter materials - for example, coal - from entering the water.

Sometimes consumables contain minerals and trace elements that make water more useful.

Pros:

A filter jug is a budget option. A jug costs from 300 rubles, a cartridge – from 150.
You don’t need to understand the installation, it’s simple to use: pour water, wait, drink.
The jug does not take up much space and is easy to lift and carry.

Minuses:

Poor performance. Water flows slowly, so the jug is designed for a family of two or three people.
May not remove all contaminants. If the tap water is of extremely poor quality, it is worth purchasing a more powerful device.
Small tank volume.

When choosing a jug, pay attention to which cartridges are compatible with it and how long they last.

The principle of operation is the same as that of a jug: water passes through a cartridge into a reservoir. Only in terms of volume the tank is more spacious; There is a small tap on it through which water is poured. Typically, dispensers have a longer cartridge life than jugs. This type of water purifier is optimal for small offices and families of more than three people.

The nozzle is attached to the mixer and purifies the water from chlorine, rust and small suspended matter. Inside there is a cassette (cartridge), which must be changed every one to three months. The main filter component is activated carbon.

Pros:

Relatively inexpensive - from 170 rubles.
Easy to use and install.
The cleaning speed is higher than that of jug filters.

Minuses:

You need to constantly remove and put on the nozzle so as not to waste purified water for washing dishes and other needs.
If excessive water flow is passed through the device, the filtration quality may be reduced.

The apartment filter is placed near the sink and connected to the faucet using a flexible hose. The device has its own tap from which purified water is supplied. The cartridge needs to be changed every 2–4 months.

Pros:

Easy to use.
The productivity is higher than that of jugs and nozzles - about two liters per minute.

Minuses:

Need free space next to the sink.
The price is higher than previous types - from 1,000 rubles.

Other names: pre-filter, mechanical (pre-) cleaning filter. It is inserted into the cold or hot water supply line. It is needed primarily to protect plumbing fixtures, dishwashers and washing machines. It is also used as a filter to purify water from a well.

For cold water, a standard prefilter is used, and for hot water, it is made from heat-resistant materials. The service life of such devices is up to 30 years.

A prefilter is not a panacea. It removes only large insoluble impurities, thus extending the life of the main filter.

Main filters are divided into several types:

Strainers trap large particles of contaminants using a mesh. The smaller the mesh cells, the more particles of different sizes it will hold. There are flushing and non-flushing devices. In the first, dirt is automatically washed off with running water. To clean the no-rinse filter, you need to rinse the mesh yourself.
Disc main filters They also clean from mechanical contaminants, but their performance is higher than that of mesh ones. Filter elements are compressed polymer discs. When the discs compress, the grooves on them form a mesh. They need to be washed promptly under running water.
Cartridge filters are replaceable cartridges. They need to be changed much more often than the mesh or discs, but the quality of cleaning is higher. Cold water cartridge housings are made of transparent or opaque plastic. Transparent is more convenient, because through it you can see how dirty the cartridge is. For hot water, housings are made of opaque heat-resistant plastic or stainless steel. Cases come in different sizes: the larger they are, the higher the performance of the device and the longer its service life.

You can install the device into the water supply yourself, but this is a labor-intensive procedure. If you are not confident in your abilities, ask a specialist for help.

Prices for a prefilter start at 1,500 rubles, there are models for 13,000.

When purchasing this type, you need to know the cross-sectional diameter of the water pipe and the water temperature for which the device is designed.

Pros:

Do not require frequent replacement.
Serves for many years.
Has high performance
Easy to use.

Minuses:

Removes only large particles.
The pre-filter is difficult to install without the help of a specialist.
To replace a cartridge cartridge, you need to shut off the water supply.

These are the most effective household filters for purifying tap water. The water goes through several stages of purification, is disinfected and softened. The system contains 3–5 sections – flasks with cartridges. Cartridges are replaced after six months to a year.

You need free space under the sink and space for an additional tap. The liquid is supplied through a separate mixer with a filter for drinking water. The device is connected to water pipes.

There are two types of under-sink filters: flow-through And reverse osmosis.

A flow-through water filter consists of three to four modules (cartridges):

pre-cleaning– from sand, rust, silt;
carbonic– from chlorine, salts, organic compounds, heavy metals;
with ion exchange resins– for deferrization and water softening;
with small particles of silver– cleanses from bacteria.

You can experiment with a set of cartridges - this way you will adjust the degree of water purification.

Some models are equipped with an ultraviolet lamp - it destroys dangerous microorganisms.

Reverse osmosis system– a special case of the “under the sink” type. A comparison of water filters shows that this is the most effective option. In such a system, water can be purified by 99%.

Cleaning goes through the following stages:

The pre-filter purifies water from large contaminants;
Water passes through the membrane - a material rolled into a roll, pore size 0.0001 microns. The membrane allows only water molecules to pass through; all other compounds are discharged into the sewer system by a forced flow of liquid.
The water is then stored in a 4-12 liter tank.

Membranes are not changed as often as cartridges - their service life is 1–5 years. The productivity of household reverse osmosis systems is 150–300 liters per day.

After such thorough purification, beneficial minerals are also removed from the water, so a mineralizer is built into the reverse osmosis system. This is a cartridge with a mineral filling that gradually dissolves in water, saturating it with magnesium, calcium, zinc, iron and other elements. Thanks to mineralization, the taste and quality of water improves. The cartridge resource is 3–4 thousand liters.