uv water purification

The history of irradiation with the ultraviolet of the aquatic environment, as a method of destroying bacteria in it, has more than one century. As far back as 1877, the ability of ultraviolet radiation (hereinafter referred to as UV radiation) to detect bacteria was determined for the first time. However, the foundations of UV technology for disinfecting water were laid only in the beginning of the 20th century (1901) after the creation of mercury discharged lamps and the possibility of their placement in a quartz cover to eliminate the influence of temperature changes in the UV lamp during the washing process with water flow. After that, in 1910, the first UV installations for sterilization of water were put into operation in Germany and France. The experience of their use has shown that there is an effect of the intensity and time of irradiation on the degree of decontamination, as well as restrictions on the use of the UV-decontamination method associated with the transparency of water. These restrictions were taken as a basis for the development of new UV sterilization plants. However, due to the fairly high cost of manufacturing UV units from the project on UV sterilization of water, they simply refused, preferring the process of chlorination of water, which at that time was more explored.

The long-term operation of water disinfection systems based on its chlorination has caused a lot of problems that have not been solved so far: firstly, the occurrence of adverse reactions of oxidation of organochlorine compounds of various kinds, including those that cause the formation of malignant tumors; Secondly, the need to clean drinking water from chlorine and chlorogenic substances at the places of their direct use; Thirdly, the wear of pipes, fittings and shut-off valves as a result of their contact with active chlorine, etc. All this required and requires, at the moment, additional huge capital investments in municipal water supply systems, as well as the necessity of installing end-of-pipe water treatment systems for drinking Water of the proper quality at places of their direct use.

Therefore, since the end of the 1970s, in a number of developed countries of Europe and the United States, as a result of the search for an alternative to chlorination of water, as the main method of disinfection, the interest of ultraviolet units has increased. But strangely enough, it was first of all connected with the problems of disinfection of wastewater. This factor has entailed stimulation of scientific research and investment of funds in the development of UV technology. Due to the significant improvement in the quality of UV sources and the design of UV radiation units, as well as their cheapness, UV technology has reached the stage when it became possible to create economical and effective UV disinfection facilities. All this allowed a new perspective to look at the problems of decontamination of water and seriously consider the possibility of widespread use of UV radiation at large water treatment plants.

However, the intensive introduction of UV-disinfection technologies for drinking water and wastewater into municipal water supply systems abroad began only from the beginning of the 80s of the XX century, which was due to the achievement of competitive operational parameters of UV installations, including energy costs, reliability, safety Etc. Over the last 10 to 20 years, several hundred thousand UV-stations of water treatment have been commissioned and successfully operated in the USA, Canada and Western Europe, with a flow rate of 10 to 500 thousand m3 / day, in addition to being created even more powerful system. The increase in the number of patents in this area outstrips practically all other methods of water treatment, which is one of the main indicators of the development of this technology.

UV disinfection was most effectively implemented in the 50's and 70's of the 20th century. At that time, large UV systems with a flow rate of up to 3000 m3 / h were created and tested. Nevertheless, the level of development of domestic light engineering and electrical engineering at that time did not allow to solve a number of fundamental technological problems, as a result of which the development of UV technology for water treatment and water treatment systems was actually stopped. Therefore, due to the low technical and operational indices of the first industrial UV units, preference was given to chlorination. Until the 1970s, the level of development of this technology remained practically at the level of achievements of those years (although ideological and technical approaches to the design of UV-units were developed by our specialists in the late 1940s).

In the mid-1970s, experts attempted to create UV-units for the defense industry, which resulted in the installation and implementation of a series of HVW (water disinfection units). However, their performance characteristics were far different from foreign models. First of all, it concerned energy consumption, the need to increase the light transmission of quartz covers, the ergonomics of products, the lifetime of UV lamps, etc. However, despite all its shortcomings, the units of the HVO were serially manufactured and successfully operated until the 90's of the 20th century.

In the years 1995-1997 of the 20th century, a series of works were carried out to determine the effect of the generalized indicators of water quality (chroma, turbidity, oxidation, COD, BOD) on the effectiveness of UV decontamination. The irradiation was subjected to river water with chromaticity in the range of 20-50 degrees, turbidity of 1-30 mg / l, BPK5 5-10 mg / l and COD 29-63 mg / l, permanganate oxidizability 6-14 mg / l. As a result of the research, it was found that the change in the parameters within the specified limits does not affect the dose of radiation necessary to achieve the normative indicators for the index and the MI.

To date, all these cumulative knowledge on UV technology is widely used in the industry.

The analysis of the latest foreign scientific literature and foreign normative documents shows that much attention is being paid to the improvement of UV-disinfection schemes of water. In order to determine the possibility of using UV-methods and UV-technologies at the state level, various studies are being conducted in many countries (programs of the US Environmental Protection Agency, the Ministry of Education, Science, Research and Technology in Germany, the EAAP in Italy, etc.)