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    Facility Gardening Irrigation Water Treatment Technology

    来源:本站  最后更新:2017-06-08 17:21:06  作者:中农天陆  浏览:434次

      The effect of irrigation water on the growth and quality of culinary crops is self-evident and is particularly important for fresh vegetables and valuable flowers. To produce high quality products, irrigation water needs to be treated to achieve higher levels of irrigation. It is one of the important ways to solve the problem of water shortage and high standard agricultural production by applying the relevant water treatment technology to deal with the irrigation water. In recent years, China has carried out the facilities of horticultural irrigation water treatment technology research, mainly biological purification treatment, gravel filtration treatment, UV sterilization treatment, reverse osmosis treatment and other technologies.
    First, biological purification treatment
      The main principle of biological purification is the use of aquatic plants and diving plants and coastal wetlands on the water quality of eutrophic substances in the biological absorption, the main application of biological purification methods are artificial near wetlands, artificial diving plants, artificial aquatic plants Floating floating island and several other, there are researchers will be two or more of them with a reasonable use, and achieved good results. Biological purification system to take artificial near wetlands, artificial diving plants and other biological purification model. Artificial wetland technology is a more mature water ecological purification technology, there are many attempts at home and abroad. The importance of suspended aquatic plants in micro-polluted water restoration is becoming more and more recognized. Suspended plants can affect aquatic ecosystems by means of nutrient competition, biomass release, and the provision of herbivorous zooplankton shelters. The stems, leaves and epidermis of suspended plants have the same effect as roots, and cortical cells contain chlorophyll , With the function of photosynthesis. This structure has a good absorption effect on different pollutants in water, especially nitrogen and phosphorus. The artificial wetland technology and aquatic plant floating floating island technology used in a total of water purification and protection, can be deep purification of water quality, and achieved good combination effect.

     

     

      In addition, in order to ensure the long-term stable operation of the biological purification system, on the one hand in the species configuration should pay attention to its growth cycle, to ensure that the four seasons have species growth; wetland plant selection should follow appropriate suitable, resistant to pollution, Strong ability, root system developed, economic and landscape value is high, pay attention to the reasonable mix of species and other principles; the other hand, supplemented by artificial management and protection measures, such as regular harvesting, aeration and oxygen, to maintain the system water purification stability The The results show that the source water of the irrigation water channel is treated by the biological purification system of the suspended aquatic plant + near - shore constructed wetland model, and the water quality indexes have achieved good results. The system can effectively improve the water SD, the removal rate of water SS 67% to 80%; improve the water DO180 ~ 300%, significantly improve the water dissolved oxygen environment; organic pollutants and nutrients have a significant reduction, COD, NH3-N, TN and TP were 26% ~ 59%, 60% ~ 73%, 7l% ~ 80% and 40% ~ 45% respectively. Therefore, it is feasible to purify the source water by using the biological purification system of this model. At the same time through a reasonable design and planting, but also to achieve a certain landscape landscaping effect. Biological purification treatment has the advantages of environmental protection and low carbon, but because of the general growth of aquatic plants with seasonal periodicity, the effect of water purification is influenced by the season, and the treatment effect is the best in summer and autumn. Therefore, a great deal of research is needed on the proper allocation of suitable species for water treatment.
    Second, gravel filter treatment

     

     

      Gravel filtration is one of the most commonly used water treatment methods in the facilities of micro-irrigation, and the proportion of applications in large and medium-sized micro-irrigation projects at home and abroad is over 70%. Quartz sand filter is the most commonly used on the filter filter media, with a variety of organic matter can be filtered, inorganic and oil impurities and other impurities (that can be larger particles to plug the emitter of various impurities) and suspended particles Refers to the floating in the water is not easy to precipitate the small particles) effect, and backwashing simple, thoroughly washed and easy to achieve automatic control.
      The core equipment for gravel filtration is a gravel filter. Sand and gravel filter is one of the multi-media filter, the sand bed is a three-dimensional filter, with a strong ability to intercept dirt, micro-irrigation system is used to remove the water in the water ideal equipment. In all filters, the use of sand and gravel filter in the treatment of organic impurities in the water 5 impurities the most effective, this filter filter and storage of impurities is very strong, and non-stop water supply. As long as the water content of organic matter more than 10mg / L, no matter how much inorganic content, should use sand and gravel filter.

     

     

      Filter tank is usually made of cylindrical, tank diameter of 0.6 ~ 1.2m, tank filter thickness of about 25 ~ 50cm. It allows the deposition of a few centimeters thick on the surface of the filter material, which is far better than the network and laminated filter. The gravel filter system is usually run in multiple tanks in order to recoil the impurities in the other tanks with the filtered water in a set of tanks. The greater the excess flow, the more tanks that need to run in parallel.
      For the facilities of horticultural micro-irrigation filter, that requires a higher filtration rate but also to remove more impurities and suspended particles, how to choose the filtration rate to consider the filter, water quality, irrigation systems and other factors, some parameters also need Through specialized research to determine.
      With the intensification of water shortages in China, a variety of recycled water sources have been used in irrigation, micro-irrigation is the most water-saving and easy to control irrigation technology, the application of renewable water micro-irrigation has many advantages, but how to deal with water quality problem The key to the promotion of this technology, gravel filtration related research for further development of poor water filtration and backwashing incentives to lay the foundation.
    Third, ultraviolet disinfection
      With the expansion of high-grade vegetables and high-grade flower cultivation area and the upgrading of quality requirements, the water quality of the clean and sterile requirements are higher. The pathogens transmitted through irrigation water are fungi, bacteria, viruses and nematodes. Although not all microorganisms are harmful to plants, but when some microorganisms into the plant may cause plant disease until death. So the bactericidal operation is to remove and kill these pathogens. UV sterilization has a thorough, safe, no secondary pollution, low cost advantages, so the study of ultraviolet light on the disinfection of irrigation water has broad prospects and practical significance.
      UV light is a band of light, also known as an electromagnetic wave, the energy determined by the frequency or wavelength. UV is usually divided into three categories: UVA (long wave UV), UVB (UVB) and UVB (shortwave UV). Since UVC has the shortest wavelength and the highest energy, it is most suitable for sterilization. The way UV deals against pathogens is to use its energy to penetrate the cell membrane and break the DNA molecules. As the DNA structure by the role of ultraviolet radiation, all the genetic data no longer exist, can not be read, so the cells cause loss or death, and therefore lost reproductive capacity.

     

     

      There are two factors that cause the loss of life of the disease cells: one is the intensity (or density) absorbed by the irrigation water when the ultraviolet action is used. Second, the role of irrigation water in the treatment room time, the product of the two known as the dose, the unit is mj / cm2.
      Although UV disinfection has many advantages, but in the course of the use of a lot of problems to be solved.
      1. When the light source energy is too small, can not even penetrate the water, the bactericidal effect drastically reduced; when the light source energy to a certain extent, increase the intensity of the light source on the contribution of bactericidal effect will be smaller and smaller.
      2. The bactericidal effect is inversely proportional to the velocity of the water flow, the faster the water flow, the worse the sterilization effect, the slower the water flow, the better the bactericidal effect. Mainly because the irrigation water by ultraviolet radiation time is too short, if the speed of the flow at the same time increase the light source energy, through reasonable regulation, can also achieve better sterilization effect, which requires a better controller system to control The
      3. The impurities in the water will also be due to adsorption of ultraviolet energy, resulting in water absorption of energy is not enough to kill the virus, through the test found that after sand and gravel filter and no water filtration through the UV disinfection, sterilization effect Very different, through the gravel filtered water after UV disinfection, which bacteria than did not pass through the gravel filter a lot less.
      4. Water treatment is not comprehensive: all irrigation water is not completely through the ultraviolet light, part of the water through the bypass channel has been completed into the sterilization of the container, mixed with each other, causing pollution.
      UV disinfection on water disinfection by many factors, mainly light source energy, water velocity and water impurities and other factors, in order to better disinfection, should use a variety of methods, reasonable to avoid and deal with the impact of various factors , Through the controller system and combined with other water treatment methods used in conjunction to achieve the best sterilization effect.
    Fourth, reverse osmosis treatment
      Penetration is a physical phenomenon. When two different salts of water, such as with a semi-permeable membrane separated will find that less salt on the side of the water through the membrane into the high salt content of water, and contained The salt does not penetrate until the salt concentration on both sides is equal. However, it takes a long time to complete this process. However, if the salt in the high side of the water, try to add a certain pressure, the result can stop the infiltration, when the pressure is called the osmotic pressure. If the pressure increases, the opposite direction can be infiltrated, and the salt is left. Therefore, the reverse osmosis desalination principle, that is, in salt water (such as raw water), applied to the greater pressure than the natural osmotic pressure, so that the infiltration in the opposite direction, the water molecules in the raw water pressure to the other side of the membrane, Into a clean water, so as to achieve the purpose of removing impurities in the water, salt. Reverse osmosis of the basic working principle is the use of a special booster pump to the original water to a certain pressure so that the role of raw water under pressure through the aperture only 0.0001μm reverse osmosis membrane.

     

     

      As the reverse osmosis semipermeable membrane has a large number of holes, the size of these holes and the size of water molecules due to bacterial viruses, most of the organic pollutants and hydrated ions are much larger than the water molecules can not pass through the reverse osmosis membrane With the reverse osmosis membrane through the water phase separation in a variety of impurities in the water, dissolved salts are the most difficult to remove. By repeatedly sampling and untreated water samples, it was found that the water after purifying the reverse osmosis unit was close to the indicators of pure water.
      Through the study found that the use of reverse osmosis treatment of irrigation water, can make the original water all the macromolecules of organic matter, impurities, bacteria, most of the salt can be effectively removed, basically close to pure water. However, in the process of reverse osmosis, if the water is not pretreated, then the impurities will plug the reverse osmosis membrane, so that the equipment purification effect and speed by a certain impact. Therefore, reverse osmosis equipment should be combined with sand and gravel filtration system, the use of reasonable system control, so that the formation of efficient and stable water treatment system.
      Facilities Gardening irrigation water because of its different sources, use different, the treatment should also be based on the actual situation and combined with the production capacity for a reasonable choice in the treatment should also be based on different needs of two or more cross-linked use , In order to achieve the best results.

     

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