The quality of modern drinking water, regardless of its delivery method, leaves much to be desired. This applies not only to central water supply, but also well water, and even artesian wells. In most cases, the problem with various kinds of pollution can be solved with the help of filters. This article will talk about various filtration methods, how and which filter to choose for water treatment, when it is advisable to use, and when it is not recommended. General selection criteria and operational features of the equipment.
Modern models of household filters have different operating principles. Their design, active substances, the presence and location of filter elements vary significantly. Before proceeding with the selection of a filter, it is necessary to understand what methods of water treatment exist and how they affect water quality.
Mechanical cleaning is used to remove solid impurities from water - sand, rust from pipes, as well as various salts and chemical additives.
The following types of mechanical filter elements are distinguished:
Mesh - a grid is used as the main element, the cell size of which depends on the level of water pollution and is 20-500 microns.
Made of synthetic fibers - A rope or cord is wound around the mesh cylinder that traps large contaminants. At the same time, during the cleaning and accumulation of harmful substances, the material changes color.
The principle of operation is based on the phenomenon of adsorption - retention of microparticles of contamination by the outer surface of filter solids. The active substance, as a rule, is activated carbon. Budget models are equipped with cartridges containing wood (birch) activated carbon. More expensive and effective cartridges are filled with activated carbon from a coconut shell, which has an adsorption capacity 4 times higher.
The main purpose is to remove various organic compounds and residual active chlorine, as well as odors associated with these substances. Filter elements consisting solely of coal have a limited spectrum of action; ion-exchange substances are mixed into the cartridge to expand it. Combined cartridges can remove herbicides, pesticides, asbestos particles, petroleum products, heavy metal ions.
By adsorbing organic substances, carbon filters can become a breeding ground for bacteria, so they can be used to clean pre-disinfected water. Restoration of sorption filters at home is impossible and, after exhaustion of their limit, they must be disposed of.
Coal sorbent cartridges
Combined sorbent cartridge
Ion exchange cleaning
Ion exchange filter elements are rarely used as stand-alone devices. They are an integral part of multi-component household cleaning appliances. The main task is to reduce water hardness. It is carried out thanks to the ion exchange (substitution) reaction, which is based on the binding of calcium and magnesium ions in water to insoluble complexes. As an active element, special synthetic resins with salts of alkali metals: potassium and sodium are used. It is these elements that react with hardness salts (calcium and magnesium) and hold them.
There are two types of ion exchange resins, anionic and cationic. They bind hardness salts due to various types of chemical reactions, but during their operation for the average consumer, the difference is practically not noticeable. Most cartridges with ion-exchange resins can be restored to working at home. It is enough to rinse them with a strong solution of sodium chloride so that the reverse substitution reaction occurs.
IMPORTANT! After the ion filter, water must be cleaned with a carbon filter.
The main disadvantage of the ion-exchange purification method is a small operating resource before the recovery process. Depending on the model, it can range from 200 to 800 liters.
Cleaning with reverse osmosis membranes
Many sellers of water filters call ultrafine cleaning devices combination devices that combine several cleaning methods. This is not true. Ultrathin cleaning involves filtering the water with membranes. During ultrafine purification, water under pressure (in some models up to 6 atmospheres) is supplied to a membrane filter with a pore size of 0.0015 to 0.1 microns. As a result of such cleaning, all harmful impurities remain on the surface of the membranes, and only water molecules pass through the membrane. Recently, with the development of nanotechnology, hollow fiber capillary membranes have begun to be used. Their use significantly reduces costs, both for maintenance of the treatment plant, and its cost.
Ultrafiltration allows you to remove mechanical impurities, organic matter, colloidal silicon, excess iron and manganese, and to conduct almost complete disinfection of the liquid. The main disadvantage of this method is the rather high installation cost and the need for constant monitoring of the condition of the filtering membranes and their systematic washing and / or replacement.
The electrochemical method of purification of drinking water is used in household filtering devices in conjunction with other methods. The main task is to improve the physicochemical and organoleptic properties of drinking water.
Installations have a rather complex structure consisting of:
1. Electrochemical reactor;
2. Sludge collector - for most models it is installed in the upper part of the device;
3. A floating cone-plug, blocking the upper hole.
4. An electrode block containing three groups of electrodes:
- Groups I and II form an electrocoagulating paired packet;
- ІІІ - consists of electroflocation electrodes.
5. Switching device - redistributing positive and negative energy charges to the cathode and anode packages of electrodes;
6. Some models have final filters.
UV - disinfection
Modules for disinfecting water by ultraviolet radiation are used in conjunction with other filtration methods. The principle of operation is based on the processing of a water stream by intense UV radiation in the wavelength range of 250-260 nm. This radiation penetrates the cell walls of viruses and bacteria, causing the destruction of DNA and RNA of the body.
This method is much more effective and safer for human health than the classic reagent method, in which water is treated with various oxidizing agents: chlorine, chlorine dioxide, sodium hypochlorite, etc. The scope of application of the UV disinfection unit is associated with its rather large size and high cost. Usually these are cottages, dachas and buildings that use artesian wells or autonomous wells for the water supply system.
The UV radiation module consists of the following key elements:
1. Power Supply;
2. Metal case;
3. UV source:
- Mercury-quartz lamp;
- Mercury-argon lamp;
4. Protective (tight) quartz casing - prevents overcooling of the lamps by the flow of water.
Depending on the declared performance, several UV lamps can be placed in one housing. The main disadvantage of this method is its complete energy dependence. Also, for effective work, it is necessary that the incoming water be of a certain quality, its physico-chemical parameters should not exceed:
- Turbidity <2 mg / L;
- Color <20 °;
- The content of iron impurities <1 mg / L.
The effectiveness of the cleaning devices depends on which water filter to choose in each case. Modern manufacturers produce many models of various treatment devices and water filters. Many of them do not have any particular benefit, and sometimes, if installed improperly or in violation of the operating conditions, are a source of biological infection.
Mud mud refers to the means of mechanical purification of water. It is a device in which a forced change in the direction of movement of water occurs. The flow passes through a special grid, leaving solid contaminants on it.
The sump consists of:
Expediency of use. Considering the characteristics of the material, sump can be used for pre-filtration of both cold and hot water with temperatures up to 150 ° C. They are installed at the entrance to the water supply system of an apartment or house, immediately behind the shutoff valves (tap). One of the purposes of this filter is to protect water meters from large mechanical impurities. They cannot produce finer cleaning.
IMPORTANT! Carefully follow the installation direction of the device relative to the water flow, usually it is indicated by an arrow on the case.
For water flowing into apartments and houses from a centralized water supply, the main types of pollution are:
- Excess active chlorine;
- Oxidized iron (from worn pipelines).
For the purification of drinking water from solid impurities, which not only significantly impair its taste, but can also damage household appliances (washing machines and dishwashers), prefilters are used.
The design consists of:
- Bracket for mounting;
- Plug-in connections for connection to the water supply system;
- Housings made of transparent plastic;
- Replaceable filter cartridge made of synthetic fibers.
Expediency of use. It is advisable to use pre-filters in cleaning systems if the water entering the house has a significant content of solid impurities. The choice of a specific model depends on the average volume of water consumption. They are used to protect gas boilers and columns, as well as washing and dishwashers, from getting into the technique of large mechanical impurities. In fact, they perform the same functions as the mud collectors, but have a greater degree of purification, dimensions, filtration rate and resource.
This type of filter is widely known, usually a filter jug consists of the following elements:
Jug filter design: 1. Lid; 2. Filter replacement calendar; 3. Locking latch; 4. handle; 5. Spout for draining purified water; 6. Capacity in the form of a funnel for the gulf of water; 7. Case; 8. Replaceable filter cartridge.
Expediency of use. Pitcher filters are used as an alternative device for treating drinking water if the domestic water supply is not equipped with stationary treatment facilities. The degree of their purification is somewhat worse, however, the cost is incomparably cheaper, which made these filters very popular. Despite a slightly worse degree of purification, using these filters you can get drinkable water. Filter jugs are equipped with various types of cartridges, which are selected depending on the contamination present in the water.
Conventional, low-cost dispenser models using purified bottled water do not have filters at all. But more expensive devices that connect to a centralized water supply system (purifaiters) have their own cleaning system.
Appearance and scheme of a universal office dispenser with a filtration system:
It consists of: 1. A mechanical cleaning filter that removes solid particles up to 5 microns in size; 2. Coal sorption cartridge that removes excess chlorine and organics; 3. Ultrafiltration membranes, removing bacteria viruses and excessive dissolved salts; 4. Carbon post-filter to remove unpleasant odors.
Expediency of use. Dispensers are water dispensing devices that are used mainly in offices.
Nozzles on the crane
The filter nozzles on the crane relate mainly to mechanical cleaning devices. They are divided into devices mounted directly on the mixer or freestanding.
Their main disadvantages are:
- Low quality water filtration;
- Reducing the flow rate, most manufacturers produce models with a recommended speed of 1-1.5 l / min .;
- An insignificant resource, for filters of "fine" cleaning it is 300-350 liters.
Expediency of use. The use of such devices is recommended only in the most extreme cases, when it is not possible to install a stationary treatment system, and the water quality is very poor. In all other cases, the use of filter nozzles on the crane is impractical.
Flow-through sorption filters
In-line sorption filters are a multi-stage filtration system consisting of 3-5 replaceable cartridges, each of which performs water purification from a special type of contamination. They are optimal in terms of price - quality of cleaning. Recommended for use with small and medium volumes of purified water consumption.
The arrangement of the main components of the flow filter: 1. A unit for connecting water; 2. The filter of preliminary sorption or mechanical cleaning; 3. Filter of deep sorption cleaning; 4. Node for connecting a crane; 5. Filter for final cleaning and conditioning; 6. The crane.
* (The set of filtering modules will depend on the specific filter model).
Expediency of use. Typically, such systems purify mechanical solids, active chlorine, iron, limestone and other chemical contaminants. When choosing a specific model, it is necessary to take into account not only the prevailing type of water pollution, but also the rate of daily consumption. Most models are equipped with a separate faucet, so that household water does not pass filtration, this additionally increases the resource of filter cartridges. It should be remembered that it is not advisable to use such systems for cleaning too hard water due to the very low resource of the ion-exchange cartridge. After the exhaustion of a certain resource, the water will cease to soften and scale will reappear in your kettle. To solve the problem of too hard water is possible only with the help of reverse osmosis systems, which will be discussed later.
Reverse osmosis systems
The reverse osmosis system is a balanced set of devices and filters for cleaning.
The device of the main components of the reverse osmosis system: 1. Filter-mineralizer; 2. Post filter for conditioning; 3. Module with reverse osmotic membrane; 4. Storage capacity; 5. Filter mechanical cleaning; 6. Filter for sorption purification; 7. Sorption filter for final cleaning; 8. The crane.
* (The set of filtering modules will depend on the specific filter model).
It consists of the following components:
1. Pre-treatment unit, which includes a mechanical, sorption and ultrafine filter.
2. Block with reverse osmosis membrane.The membrane consists of a polymer with a pore size of 1-15 angstroms for high-purification devices and 10-70 angstroms for nanofiltration units.
REFERENCE: 1 micron is 10,000 angstroms.
3. Storage tank. Since the speed of water purification by reverse osmosis is quite low, a system must be provided in the system for the accumulation of filtered water. The volume of the tank must be selected in accordance with the daily intake of drinking water.
4. Postfilter - is installed after the storage tank to eliminate unpleasant odor and taste.
5. Shutoff and connecting fittings. Given the low speed of cleaning with reverse osmosis, it is impractical to use filtered water for domestic purposes, it is mainly used for cooking and drinking. Therefore, the system must have a separate crane.
The process of water softening is to reduce the amount of hardness salts, mainly chlorides and sulfates. For this, replaceable cartridges with a cation exchange resin are used, which adsorbs salts from water, giving in return hydrogen and sodium ions. The use of soft water is not only good for health, but also will keep household appliances in good condition. They produce such filters of various capacities.
Expediency of use. Before purchasing and installing a filter with a cation exchange resin, it is necessary to check the water hardness level. It is advisable to use softening if the water hardness index is higher than the recommended 1.0–2.0 mEq / l. It is also important to know that such filters do not purify water from metal salts and bacteria, their purpose is to soften water, which contains a large amount of hardness salts. If water is supposed to be used for drinking, then you should take care of the presence of sorption filters used to purify water from other harmful impurities. If you plan to use a softener to protect washing machines from scale formation, then one softener will be enough.
The results. If you want to get really high-quality water for cooking products, tea, coffee and just drinking water, then you need to look in the direction of flow-through sorption filters and reverse osmosis systems. No nozzles and jugs can not replace them. It should be remembered that these systems are much more expensive. If you cannot afford to install such systems, then as an option you can use a filter jug with a specific cartridge.
Post-filters are used in reverse osmosis systems and in-line filter kits to eliminate unpleasant odors and improve the taste of purified water. As the active element, granular or powdered activated carbon in a polymer case is used. The placement of fittings for connection depends on the specific model and which device the filter will be connected to. In addition, mineralization filters are used in reverse osmosis systems. Since after passing through the osmosis membrane all useful minerals are removed from the water, such mineralizers are used to restore them. They restore the natural mineralogical composition of water.
We determine the pollution of water
The effectiveness of the applied cleaning system, and therefore, the quality of the filtered water, depends on the specifics of the pollution. Before you determine which water filter to choose for your home, you need to perform a comprehensive analysis of the water coming from the water supply. Analysis should be done regardless of whether a well is being drawn from a well, artesian well or centralized water supply. Only after analysis will it be clear which filter and with which filter elements are needed. Based on this, the filter is selected.
Water problems, their manifestations, causes and filters to eliminate:
|Problem||How does it manifest||Cause||Filter or cartridge used|
|Corrosively active water at neutral pH.||Copper and bronze pipes and valves are actively corroded with the appearance of greenish smudges.||The water is oversaturated with oxygen, sampling was carried out from the surface layers or very deep wells.||Ion exchange cartridge.|
|Reverse osmosis system.|
|Hard water||Limestone scale on heating elements of household appliances.||The presence of limestone, calcium and magnesium salts in water.||Ion exchange cartridge.|
|Reverse osmosis system.|
|Insoluble particles, sand, etc.||Silt sediment in the sink.||Mud clogged, excess pollution.||Install or increase the coarse mechanical filter.|
|Smell - fishy, musty or woody||It manifests itself usually during floods (from melting and rain).||Abstraction of water from the surface together with organic compounds.||Sorption carbon cartridge + UV disinfector.|
|Postfilter + UV disinfector.|
|Smell of chlorine||-||Excessive chlorination.||Sorption cartridge of any type.|
|The smell of hydrogen sulfide (rotten eggs)||The formation of gray or yellow spots on the dishes and sink, unpleasant taste.||The presence of dissolved hydrogen sulfide and / or sulfuric bacteria, which cause the appearance of hydrogen sulfide.||Sorption cartridges of any type.|
|Sorption + UV disinfector (if the problem is in bacteria)|
|Chemical smell of detergents||Water foams slightly.||Drainage from septic tanks into aquifers.||Sorption carbon cartridges.|
|The smell of petroleum products||-||Leakage of petroleum products into the aquifer.||Reverse osmosis system.|
|Turbid water with the smell of methane||-||The result of decomposition of organic matter in oil producing areas, aquifers pass through the place of the old landfill.||Reverse osmosis system.|
|The smell of phenol (chemical)||-||Chemical fluids entering aquifers.||Reverse osmosis system;|
|Brackish water||Laxative effect.||Discharge into aquifers of industrial effluents.||Ion exchange;
|Reverse osmosis system.|
|High acidity||Metallic aftertaste.||High iron content, natural increased acidity over 4.5 pH.||Sorption cartridge for water deferrization.|
|Ferruginous water||When washing, the laundry takes a yellowish tint, when heated, the water turns brown.||The presence of ferrous iron in a concentration of more than 0.3 mg / L.||Sorption cartridge for water deferrization.|
Filters for hot or cold water
The vast majority of filters are designed for cleaning cold water. The upper temperature limit of such treatment systems is 35 - 40 0C. Therefore, if you need to clean hot water, you will have to look for filters whose temperature limit is at least 95 0FROM.
Filter performance is the ability to pass it through and clean a certain amount of liters of water per minute. The reverse osmosis systems have the lowest productivity, since water takes a long time to pass through the reverse osmosis membrane. But, so that users do not have to wait too long when the required amount of water is collected, such devices are equipped with expansion tanks, where there is always a certain amount of prepared water. Also, filter jugs have a small productivity. When choosing a filter, you need to determine how often you intend to use the filter and how much purified water you need during the day.
Filter module resource
Almost every filter has a filter module, which is designed to clean a certain amount of water. After exhausting its resource, the filter module will not be able to provide the proper quality of water and must be replaced.Before choosing a filter, you can calculate the applied water consumption and select one or another filter element based on the calculation data. Please note that in systems with a multi-stage cleaning system, each cartridge has its own filtering abilities and resource. This means that the cartridges will be replaced at different times, and not all at once.
Contrary materials, their cost and availability
Before you buy a particular filter model, you need to ask about the availability of cartridges on sale and their cost. It often happens that the manufacturer puts a small price on the filtration system itself, but the cost of the cartridges is disproportionately high, which leads to high costs for maintaining the system throughout the entire period of its use. In addition, find out if cartridges and supplies are available for sale in the city or region where you live. Sometimes it is difficult to buy certain filtering modules and when they are on sale you have to buy pro-stock, which is also costly and inconvenient.
To know how to choose a water filter is not enough, you still need to be able to distinguish quality products from fakes. In the world there are many fakes of various products and filters are no exception. Having bought such equipment there is a risk to give money, and the water quality will remain at the same level.
To protect yourself from buying a fake, you need to pay attention to the following points:
- Manufacturer fame
- Product Cost Level
- Appearance of goods
- Availability of certificates
- Availability of a hologram, marking of its own application, a unique serial number
Manufacturer fame. As in any other niche, there are manufacturers who have been working in this market for a long time and have proven themselves well. Each of them has its own developments and patents for various systems used for water purification. The most famous manufacturers of household filters for water purification are companies such as: Barrier, New Water, Aquaphor, Geyser, Atoll and others. when choosing a filter, you should focus on the products of these brands.
The level of value of the goods. Consumer opportunities of our citizens are at a low level, hence the desire to save. When buying a filter you need to be careful. If you see that the price of the model offered to you differs markedly from the average price in the market, then it is worth considering where this seller got this product. If the product was purchased from an official supplier, but its price is significantly different from the price in other stores, then this is a hundred percent fake. After all, the seller cannot trade at a loss and give it at cost also makes no sense.
Appearance of the goods. Cost can not always say about the poor quality of the product, because it can be set at the same level as other sellers. Therefore, when buying the filter model you need, look at the quality of the material and assembly. the fake always differs from the original in various little things. Pay attention to the seams of the flasks, the threads of the outlets for connecting to the water supply, equipment, etc. Everything should be at the best level. In addition, pay attention to the quality of packaging - no one fakes packaging in high-quality materials. Non-compliance of these trifles with high standards may mean that you have a fake.
Availability of certificates. If you have any doubts, ask the seller to show a certificate of quality for the products. At the same time, pay attention to the certificate must be genuine, and not be a photocopy of many years ago.
The presence of a hologram, marking of the application, a unique serial number. To protect their products, manufacturers supply them with various galagrams, documents with special markings, and some with unique serial numbers with the possibility of authentication.It is enough to drive such a number into a special form posted on the official website of the manufacturer and you will receive an answer whether your model is genuine.
When choosing a filter, it is necessary to remember that to remove water from chlorine, dissolved salts of iron, to soften it, etc. only filters equipped with sorption, ion-exchange type cartridges and / or modules with a reverse osmosis membrane can do it. It is impossible to perform high-quality water purification without using sorbents and / or reverse osmosis membranes. In addition, a high-quality filter will have several degrees of purification and, accordingly, cartridges. It is not possible to clean various impurities with the same cartridge or module. If you are trying to sell some kind of “miracle” filter that does not contain the above cleaning modules, while the manufacturer assures that it can purify water from all impurities, then they just want to deceive you.
Any of the cartridges used in the cleaning system has its own resource, after which its performance must be replaced or disposed of. As a rule, it is expressed in the number of liters of treated water or the operating time, but taking into account the average norms of water consumption per day per person. Mechanical filters must be periodically cleaned from accumulated contaminants. If you do not adhere to the operating rules, the treatment system can become a source of biological pollution.
Most companies produce unified cartridges for the entire line of filtering devices. If the cleaning device is a series of flasks. Then you can use cartridges from other manufacturers, provided that the overall dimensions are suitable. Cutting or opening cartridges is strongly discouraged.