Today, innovative technologies allow high-quality water purification from various contaminants on a large scale. At the same time, the population, production and technical facilities are provided with high-quality liquid. In the process of water treatment, different techniques are used. They allow you to meet all the requirements of the current GOST.
One of the most successful methods today is ultraviolet disinfection of water. This approach successfully fights certain types of contaminants, allowing large-scale liquid processing. The essence and effectiveness of this method, its advantages and disadvantages will be considered below.
general characteristics
Today, disinfection of water with ultraviolet radiation is a popular technique that is used in combination with other types of treatment. The presented processing is carried out everywhere. This is the primary stage of water disinfection. It allows you to get rid of harmful microorganisms in the liquid.
In the process of applying this reagentless method, water is irradiated with ultraviolet light of a certain part of the spectrum. This is electromagnetic radiation, the wavelength of which can be from 250 to 270 nm. It should be noted that the ultraviolet part of the spectrum includes rays that are in the range from 10 to 400 nm. Modern installations that make it possible to disinfect water produce radiation with a wavelength of 260 nm. In this case, the liquid is not only cleansed, but also softened.
When using this approach, other techniques are also used. This can be chlorination of water, as well as hypochlorination. The presented processing stage is mandatory, according to GOST when carrying out liquid purification.
The principle of the method is based on the ability of ultraviolet radiation to penetrate cell membranes, destroying their DNA and RNA. She loses her ability to divide. The presented technique allows you to completely eliminate the negative impact on the human body of microbes and bacteria that are in the water. The strength of the exposure depends on the duration of exposure. There are certain standards for such a disinfection.
Standards and requirements
There are certain standards and rules that apply when conducting water treatment and testing. They coordinate the activities of services that deal with the disinfection of liquids. Such regulatory documents include guidelines MU 2.1.4.719-98, approved by the Ministry of Health of the Russian Federation, as well as the current GOST "Drinking water" R 56237-2014.
The presented regulatory documents regulate the procedure for water purification using ultraviolet radiation.
The guidelines provided describe the characteristics of the minimum radiation dose that is used for drinking water. This indicator is 16 mJ / cm². Studies conducted by scientists have shown that with this treatment intensity in water, the number of pathogenic bacteria is significantly reduced. This indicator is 5 orders of magnitude. The number of viruses during this treatment is reduced by 2-3 orders of magnitude.
The current GOST "Drinking Water" regulates the interaction of all services that provide liquid processing. The standard defines the basic requirements for the production of quality measurements and cleaning. So, according to this document, drinking water in its quality must comply with sanitary and hygienic requirements. It can be used to meet drinking and domestic needs. When using such a liquid, it is possible to produce foods consumed by humans.
Method effectiveness
To obtain clean, clear water, it is not enough to use only ultraviolet radiation. There is a whole range of procedures that can demonstrate a high processing result. Only after they can be obtained drinking water.
The effectiveness of ultraviolet disinfection has a number of conditions. In order to obtain a high quality end result, it is important to choose the right dose for the fluid treatment. Its effectiveness depends on the intensity and duration of the treatment. Various microorganisms are more or less resistant to such effects. For bacteria, the dose may be less. For viruses, such treatment has less impact. It should be noted that the most resistant microorganism to such a treatment is E. coli. Therefore, before treatment, the presence of bacteria in the water is determined.
Also, when calculating the dose, the total number of bacteria and microbes that are in the liquid is determined.
The quality of the irradiated water is also of great importance. It may contain a different amount of impurities. Clean, clear water is better for disinfection than a cloudy liquid. This is explained by the degree of passage of water deep into the layers. In order for the presented treatment to be effective, the amount of impurities must be determined in a substance less than the maximum permissible value.
Standards and guidelines provide for how much iron, large particles of pollutants, and the color category of the liquid should be in the liquid. If these figures are too high, processing will be ineffective. Behind these tiny particles, like behind a shield, some of the bacteria and viruses can hide. Therefore, during processing, they will not die. Energy costs will be useless. Before disinfection begins, water is purified from iron impurities.
Method Advantages
Knowing the principle of action of ultraviolet disinfection of wastewater, a number of advantages of the presented method should be highlighted. The procedure belongs to the category of the cleanest approaches. When it is carried out, no chemicals or additional substances are added to the water. The negative impact of ultraviolet radiation on the human body can be only with prolonged exposure. This type of disinfection does not change the chemical and physical qualities of the liquid. This eliminates even indirect effects on the body.
The advantages of the method should also include its versatility. It effectively acts on almost all microorganisms. It is also a fairly economical method. It is used in most cases of disinfection. In the presence of E. coli or other microorganisms resistant to ultraviolet radiation in the water, ozonation is used. This approach is considered more expensive.
Liquid irradiation time does not exceed several seconds. This provides an instant effect when carrying out such an impact. There is no danger to exceed the dose of treatment. Water can be irradiated for any length of time. At the same time, its physical and chemical qualities will not change. The processing efficiency with prolonged exposure will be higher.
When disinfecting water with ultraviolet radiation, it is possible to significantly reduce the number of reagents that are used after irradiation. Also, this method does not require high energy costs, compared, for example, with ozonation. Therefore, it is used everywhere.
disadvantages
Pure drinking water is obtained during the processing of liquids by various methods. The disadvantage of ultraviolet radiation is the inability to exert a corresponding effect on all microorganisms. Some of them have high UV resistance. If such bacteria or viruses are found in large quantities in water, it is treated in a different way.
One of the drawbacks of the method is the need for monitoring the level of iron. The liquid should not contain various suspended particles of contaminants. Otherwise, the processing will be ineffective. The higher the dispersed impurities of a sufficiently large size in water, the worse the final result of the treatment will be.
In order for the installation that performs water disinfection with ultraviolet light to be able to perform the procedure with high efficiency, the technique involves preliminary cleaning. This allows you to remove impurities, coarse particles of contaminants from water. Also, after the procedure, it is necessary to carry out chlorination of water.
The action of the ultraviolet installation is one-time. This does not guarantee that after disinfection in the water, various bacteria and viruses will not appear again. Due to its shortcomings, the presented technique is most often used in combination with other methods. However, in the absence of other pollutants in the water, ultraviolet can be used as an independent approach. The disadvantages of this method cannot overlap its advantages.
Features of disinfecting devices
Installation of UV-disinfection of water does not differ in high design complexity. This makes the equipment easy to use, reduces the likelihood of breakdowns. The design of the installation has the form of an elongated tube made of metal. Inside it is an ultraviolet lamp. Also, all models have quartz cases. Lamps are installed in them.
The construction work is simple. Water enters the unit. It runs from the inside of the quartz case. At this time, the liquid receives the necessary dose of disinfection. The quartz case in the design protects the lamp from damage. Therefore, water washes this particular part of the installation.
The lamp is a complex design. In its body, a certain type of metal evaporates. Most often, these devices use mercury. This metal is most often used in the process of disinfecting water. The lamp must emit ultraviolet waves of a certain length. This indicator is affected by the pressure of the internal mercury vapor of the lamp bulb.
Ultraviolet disinfection of water can only occur under certain conditions. On sale are high, low and medium pressure lamps. However, when disinfecting water, not all designs are used. To carry out such a procedure, only those lamps are suitable, in which the pressure will be low or medium. The first option is preferable. It is these lamps that are capable of emitting radiation with a wavelength of 260 nm. Such devices are marked by high energy efficiency and a long service life.
Varieties of lamps
Today, various ultraviolet water disinfection systems are on sale. The highest efficiency known low-pressure lamps. They have a low power rating. Their lamps are made of uviole glass. This can significantly reduce energy loss.
Over time, each lamp gradually loses its radiation intensity. How soon the lamp will lose its original quality is an important argument in the issue of acquiring a particular model. At the end of its useful life, the lamp power may be only ¼ part of the nominal initial value.
Today, the market of ultraviolet emitters presents products of both domestic and foreign production. World-famous companies are UV-technik (Germany), Atlantic Ultraviolet (USA), Hanovia (Great Britain). The last of these companies is the oldest in the world in the production of such irradiators. Lamps from the Dutch company Philips are also in demand in our country.
All of these lamps are used in their installations by the largest manufacturers of such equipment. Domestic lamps are also in demand. For example, in the ultraviolet water disinfection units UDV, which are popular in our country , which are manufactured by NPO LIT, lamps of our own production by the company brand DB are used.
Varieties of installations
UV-disinfection of water occurs using different installations. One of the popular firms is BWT. It produces water irradiation devices called Bewades. Such devices are characterized by a radiation dose of 40 mJ / cm². Therefore, these plants are used to treat both waste water and drinking water. They use Philips lamps. Their duration is 11-14 thousand hours.
In the market of special products for water purification, many domestic plants are presented. They use high-quality lamps of both domestic and foreign production. So, the products of the National Water Resources company are known in our country. She launches the Shine installation on the market. These appliances have Philips lamps.
Another well-known product in our country is the BAKT installation. It also has lamps from the Dutch brand Philips. Many designs of domestic production include a system for monitoring the intensity of exposure.
A large selection of plants is offered on the domestic and foreign markets by NPO LIT. About 30 different plant modifications are produced. You can order an individual type of design that allows you to disinfect water in the field or other varieties.
Features of water treatment
Pure drinking water can be used by humans for various purposes. To get such a liquid, you will need to perform certain manipulations. If water comes from a surface source, the radiation dose should be 25 mJ / cm². In this case, the transparency coefficient of the liquid should be at least 70%.
For underground sources, the dose should be the same as for surface sources. However, the transmittance of ultraviolet rays should be at least 80%. Previously, such water before disinfection is treated using sorption techniques.
Liquid from any source can be cleaned using membrane filters. In this case, the transmittance of the rays should be 90%, and the radiation dose should be 25 mJ / cm².
Drinking water disinfection is different from wastewater treatment. For such fluids, the radiation dose should be greater. It is 30 mJ / cm².
Installation Recommendations
Ultraviolet disinfection of water will be effective with the right choice of equipment and cleaning method. Each unit on sale is characterized by a different performance. The exposure is continuous. Therefore, performance is affected by the speed at which water flows inside the unit.
It should be noted that the performance could be significantly increased if there was a storage tank in the system. However, for the presented disinfection principle, such a design refinement is unacceptable. The action of the rays is one-time. Therefore, when the treated liquid is mixed in a tank with dirty water, it will be infected again.
When choosing, you need to consider what dose the unit irradiates with water. If the water is sufficiently muddy, high power equipment will be required. Otherwise, such disinfection will be ineffective. Also, the number of microorganisms in the liquid affects the dosage of radiation. The more of them, the stronger the radiation dose should be made by the installation.
Given all of the above parameters, you can choose the best option equipment. So, the domestic manufacturer NPO LIT offers a large selection of ultraviolet irradiators. Their cost varies significantly depending on performance indicators. The price can be from 20.5 to 826 thousand rubles.
Having considered the features of ultraviolet water disinfection, you can correctly select and use equipment for irradiation of liquids.