Agricultural saline-alkali tail water grading purification system and purification method thereof in arid region

Abstract

The application discloses a tail water grading purification system for arid saline-alkali farmland, and discloses a purification method thereof, and belongs to the technical field of energy saving and emission reduction. Through the tail water detection system, the preliminary purification treatment system and the deep purification treatment system, and the purification treatment system comprising multiple water purification modules, multi-stage purification of the tail water of the farmland is realized. The whole system comprises three-stage detection, a special toxic detection module is arranged, the safety of the produced water is ensured, the recycling of the inorganic salt in the preparation process is realized, the whole process is controlled and decided through the central control system, the operation cost is reduced, the system is economic and practical, energy-saving and environment-friendly, and the problem that the tail water of the farmland is complex in composition, contains a large amount of inorganic salt, heavy metal ions and organic matter and is difficult to treat is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of energy saving and emission reduction, and in particular to a grading purification system for tail water of saline-alkali farmland in arid areas and a purification method thereof. BACKGROUND

[0002] In the northwest arid areas of China, drought and rain are scarce, and evaporation is strong. For a long time, the problem of salt accumulation has been highlighted, and local agriculture is facing the crisis of soil degradation and crop yield reduction. In recent years, the irrigation and drainage coordination measures such as subsurface drainage and flood irrigation for salt washing have attracted much attention. However, the discharged tail water of farmland not only takes away the salt, but also causes the loss of nitrogen, phosphorus, potassium and other nutrients in the soil. More seriously, due to the unreasonable use of pesticides and fertilizers in the process of agricultural production, the tail water of farmland even contains residual pesticides or harmful metal elements. If it is not treated and directly discharged, it will not only cause secondary pollution of water sources or soil, but also waste a lot of water resources. Therefore, how to effectively treat the tail water of farmland with complex composition and large quantity, and realize efficient wastewater reuse, has important practical significance for the sustainable development of arid area water-saving farmland.

[0003] At present, the common water purification technology mainly has the following three schemes:

[0004] First, through the synergistic effect of medium-plant-microorganism in ecological wetland system to degrade and convert organic matter and impurities in wastewater.

[0005] Second, through the use of adsorption-microfiltration technology to efficiently separate solid and liquid of wastewater.

[0006] Third, through the electrochemical water treatment technology to directly oxidize ammonia nitrogen in wastewater or generate precipitate.

[0007] In summary, the traditional water purification method has the disadvantages of high water purification cost, complex water preparation process, long water purification period, and cannot meet the demand of large water demand, etc., and the waste reuse rate is low, which is easy to cause environmental pollution and resource waste. In addition, the electrochemical water treatment technology also has the disadvantages of large voltage fluctuation of electrode plate, low current efficiency, and unsatisfactory heavy metal ion removal effect. More importantly, the existing technology mainly focuses on the purification of single component water, and there are few composite purification technologies for the tail water of saline-alkali farmland in arid areas which contains a large amount of inorganic salt, heavy metal ion and organic matter. SUMMARY

[0008] (I) Technical problems solved

[0009] In view of the deficiencies of the prior art, the present application provides a dry area saline farmland tail water grading purification system, and provides a purification method thereof and a computer device carrying the purification method application program, realizes dry area saline farmland tail water composite purification, solves the problems of small water purification capacity, long water purification period, low waste recovery rate of traditional water purification technology, and cannot handle dry area saline farmland tail water with complex composition, containing a large amount of inorganic salt, heavy metal ion and organic matter.

[0010] (II) Technical scheme

[0011] In order to achieve the above object, the present application is realized by the following technical scheme:

[0012] The dry area saline farmland tail water grading purification system is characterized in that it comprises tail water detection system, preliminary purification treatment system and deep purification treatment system arranged in sequence.

[0013] The tail water detection system comprises salinity detection module, water quality detection module and toxicity detection module, and is used for detecting farmland tail water salinity, water quality and toxicity.

[0014] The preliminary purification treatment system comprises physical adsorption module, tail water electrolysis module and biological purification module arranged in sequence for preliminary purification treatment of farmland tail water, and comprehensive detection module 1 for detecting water quality and toxicity.

[0015] The deep purification treatment system comprises tail water heating module, evaporation crystallization module and tail water condensation module arranged in sequence for further treatment of the farmland tail water after preliminary purification, and comprehensive detection module 2 for detecting salinity.

[0016] The tail water detection system, preliminary purification treatment system and deep purification treatment system are electrically connected with the central control system, and the central control system is used for analyzing whether the farmland tail water quality, salinity and toxicity meet the standards, feeding back through the monitoring feedback module, and making decisions.

[0017] Preferably, the physical adsorption module comprises a filter tank, which adsorbs, deodorizes and preliminarily purifies the farmland tail water through an activated carbon filter, and filters the impurities insoluble in water.

[0018] The tail water electrolysis module comprises an electrolytic tank, and a multi-electrode electrolysis device is fixed on the electrolytic tank through bolts, which electrolyzes the farmland tail water after filtration and adsorption through the multi-electrode electrolysis device to remove most of the organic matter and heavy metal ions.

[0019] The biological purification module comprises a regulating pool, a first wetland unit and a second wetland unit arranged in sequence; the regulating pool is used for regulating water volume and balancing water quality, and continuously and quantitatively supplies water to the wetland units through a water pump; the first wetland unit and the second wetland unit respectively perform primary and secondary purification on residual organic matter, heavy metal ions and part of inorganic salts in the tail water of the saline-alkali farmland.

[0020] Preferably, the first wetland unit uses coarse sand (particle size 1 mm) as the adsorption substrate, and the second wetland unit uses waste brick blocks (particle size 10-30 mm) as the adsorption substrate, and the wetland units are mixedly planted with the wetland plants Phragmites australis and Typha angustifolia which are tolerant to salt and alkali.

[0021] Preferably, the grading purification system of the tail water of the saline-alkali farmland in the arid region is powered by a solar photovoltaic panel.

[0022] The electrolytic cell is sawtooth-shaped, the multi-electrode electrolysis device is composed of multiple groups of series-connected cathode and anode electrode devices, the cathode material is graphite, and the anode material is a Fe-Al mixed plate (proportion 1:1), and the electrode plate spacing is 100 mm. Among them, each cathode material and anode material is connected in series by copper wire, and there are 6 pairs in total, and each pair of electrodes is connected to the solar photovoltaic panel by copper wire.

[0023] Preferably, the current adjustment period of the multi-electrode electrolysis device is 1 h, and the current density control interval is 10-100 mA / cm 2 , with a variable range of ±10 mA / cm 2 .

[0024] Preferably, the tail water heating module comprises a solar heat collecting vacuum tube, which is used for heating the high-salt-content tail water of the saline-alkali farmland after the preliminary purification treatment system.

[0025] The evaporation crystallization module comprises a flash tank and a salt drying box, the tail water of the saline-alkali farmland treated by the tail water heating module is heated and evaporated again through the flash tank, and the inorganic salt evaporated and crystallized is collected through the salt drying box.

[0026] The tail water condensing module comprises a circulating condenser, which is used for condensing the evaporated water vapor of the flash tank.

[0027] Preferably, the solar heat collecting vacuum tube is made of quartz, has a heat absorbing coating on the surface, and is provided with an adjustable support, so that the heating angle can be adjusted in real time according to different geographical positions and seasonal rules.

[0028] The flash tank realizes efficient evaporation crystallization of the tail water of the saline-alkali farmland by adjusting the vacuum degree and the temperature of the tail water at the inlet.

[0029] The circulating condenser is a multi-tube-pass arranged shell-and-tube circulating condenser.

[0030] Preferably, the tail water detection system comprises a water storage pool, the salinity detection module is a salinity detector, the water quality detection module is a water quality detector, and the toxicity detection module is a toxicity sensor, and the salinity detector, the water quality detector, and the toxicity sensor are fixed on the inner side of the water storage pool by bolts;

[0031] The preliminary purification treatment system further comprises a water outlet pool, the comprehensive detection module 1 is installed in the water outlet pool, and the comprehensive detection module 1 comprises a water quality detector and a toxicity sensor;

[0032] The tail water treated by the deep purification treatment system enters a clean water pool, the comprehensive detection module 2 is installed in the clean water pool, and the comprehensive detection module 2 comprises a salinity detector;

[0033] The salinity detector, the water quality detector, and the toxicity sensor are respectively used for detecting the salinity, the water quality, and the toxicity of the tail water.

[0034] The purification method of the arid saline-alkali farmland tail water grading purification system comprises the following steps:

[0035] Step one, detecting the salinity, the water quality, and the toxicity data of the farmland tail water entering the tail water detection system by a salinity detection module, a water quality detection module, and a toxicity detection module;

[0036] Step two, recording the salinity, the water quality, and the toxicity data of the farmland tail water entering the tail water detection system by a central control system, comparing the data with standard values in a database, and then feeding back to a monitoring feedback module for display; the central control system makes a decision according to the tail water detection comparison result, when the salinity or the water quality or the toxicity detection result is not over standard, the tail water does not need to be purified and can be directly used, and when any index is over standard, step three is performed;

[0037] Step three, performing preliminary purification treatment on the farmland tail water by a physical adsorption module;

[0038] Step four, sequentially performing preliminary purification treatment on the farmland tail water by a tail water electrolysis module and a biological purification module, and detecting the farmland tail water after the preliminary purification treatment again by a comprehensive detection module 1;

[0039] Step five, recording the water quality and the toxicity data of the farmland tail water entering the comprehensive detection module 1 by a central control system, comparing the data with standard values in a database, feeding back to a monitoring feedback module for display, and making a decision according to the tail water detection comparison result, when the water quality or the toxicity detection result is not over standard, step six is performed, and when any index is over standard, step four is performed again;

[0040] Step six, performing heating treatment on the farmland tail water by a tail water heating module;

[0041] Step seven, the heating water treated by the tail water heating module is evaporated and crystallized by the evaporation crystallization module, and the water vapor of the evaporation crystallization module is condensed and liquefied by the tail water condensation module, so as to realize deep purification treatment of the tail water of the farmland, and the tail water of the deep purification treatment is detected again by the comprehensive detection module 2;

[0042] Step eight, the central control system records the salinity data of the tail water of the farmland entering the comprehensive detection module 2, compares it with the standard value in the database, and then feeds back to the monitoring feedback module for display, and makes a decision according to the tail water detection comparison result, when the salinity detection result is not over standard, the purification is completed, and when the salinity is over standard, step seven is performed again.

[0043] A computer device comprising a memory, a processor and a computer program, the computer program being stored on the memory and executable on the processor, characterized in that the processor implements the steps of the purification method of the arid saline farmland tail water grading purification system as described above when executing the computer program.

[0044] (Three) beneficial effects

[0045] (1) The present application is controlled by the central control system, purified by the preliminary purification treatment system and the deep purification treatment system, each system is provided with multiple purification modules, which realizes rapid and large-scale water purification, meets the requirement of large amount of water, solves the problem of complex composition of tail water of farmland, and a large amount of inorganic salt, heavy metal ions and organic matter are not easy to handle. After three-stage detection, and the unique addition of the toxicity detection module, the safety of the prepared water body is ensured.

[0046] (2) The present application is based on the response difference of each heavy metal ion to current intensity in the electrolysis process of the electrochemical water treatment technology and the rich light and heat conditions in the arid area, which is conducive to solar photovoltaic power supply. By adjusting the current density (current size and direction) and electrolysis period of the multi-electrode electrolysis device, the removal effect of heavy metal ions is ideal, the operation is simple, and the cost is low.

[0047] (3) The present application combines electrochemical water treatment technology with small ecological wetlands, introduces organic matter and impurities that cannot be completely removed in the electrolysis process into multi-stage ecological wetlands, further strengthens the denitrification and phosphorus removal capacity of the water purification system, and deeply treats the tail water of the farmland.

[0048] (4) The tail water removed of heavy metal ions and organic matter is heated by a solar heat collection vacuum tube, and the vacuum degree of the flash tank and the temperature of the tail water at the inlet are adjusted to realize evaporation crystallization at the same time, which not only efficiently desalinizes the tail water of the saline farmland, but also recycles and recycles a large amount of inorganic salt, which is economical and practical, energy-saving and environment-friendly. BRIEF DESCRIPTION OF DRAWINGS

[0049] Figure 1It is a schematic diagram of system principle of the tail water grading purification system of the saline-alkali farmland in arid area.

[0050] Figure 2 It is a schematic diagram of structure principle of the tail water grading purification system of the saline-alkali farmland in arid area.

[0051] Figure 3 It is a logical diagram of purification method of the tail water grading purification system of the saline-alkali farmland in arid area.

[0052] In the figure: 1. salinity detector; 2. water quality detector; 3. toxicity sensor; 4. multi-electrode electrolysis device. DETAILED DESCRIPTION

[0053] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0054] Please refer to Figures 1-3 The embodiments of the present application provide a technical solution:

[0055] Please refer to Figure 1 The tail water grading purification system of the saline-alkali farmland in arid area, characterized in that, comprising tail water detection system, preliminary purification treatment system and deep purification treatment system arranged in sequence; the tail water detection system comprises salinity detection module, water quality detection module and toxicity detection module, and is used for detecting the salinity, water quality and toxicity of the tail water of the farmland; the preliminary purification treatment system comprises physical adsorption module, tail water electrolysis module and biological purification module arranged in sequence and used for preliminary purification treatment of the tail water of the farmland, and comprehensive detection module 1 used for detecting water quality and toxicity; the deep purification treatment system comprises tail water heating module, evaporation crystallization module and tail water condensation module arranged in sequence and used for re-treatment of the tail water of the farmland after preliminary purification treatment, and comprehensive detection module 2 used for detecting salinity; the tail water detection system, the preliminary purification treatment system and the deep purification treatment system are electrically connected with the central control system respectively, and the central control system is used for analyzing whether the water quality, salinity and toxicity of the tail water of the farmland meet the standards, feeding back through the monitoring feedback module, and making decisions.

[0056] The tail water detection system is arranged to preliminarily detect the farmland tail water, the detection result is analyzed and processed by the central control system, and a decision is made, the preliminary purification treatment system and the deep purification treatment system are arranged, and a plurality of treatment modules are further arranged in each system, so that multi-stage purification of the farmland tail water is realized, the purification efficiency is higher, the purification effect is better, the biological purification module is arranged to reduce the purification cost, the evaporation crystallization module is arranged to realize evaporation crystallization of inorganic salt, and the inorganic salt can be recycled, which meets the policy requirements of developing saline water resources in recent years.

[0057] In use, the central control system records the salinity, water quality and toxicity data of the farmland tail water entering the tail water detection system, and compares them with the standard values in the database, and when the detection result is appropriate, the tail water does not need to be purified, and when any one of the indicators is inappropriate, the tail water enters the preliminary purification treatment system through the pipeline for primary purification, and is first adsorbed and deodorized through the physical adsorption module. After being treated by the physical adsorption module, the tail water enters the tail water electrolysis module through the pipeline, and after being electrolyzed to remove most of the organic matter and heavy metal ions, the tail water enters the biological purification module through the pipeline. After being treated by the biological purification, the tail water enters the comprehensive detection module 1 through the pipeline for detection, and is analyzed and decided by the central control system. If it is unqualified, the water body is sent back to the tail water electrolysis module through the pipeline for repeated treatment, and if it is qualified, it enters the deep purification treatment system. The tail water is heated by the tail water heating module to provide hot water for the evaporation crystallization module, and is evaporated by the evaporation crystallization module to obtain steam and salt crystals, the steam is condensed by the tail water condensing module, and the salt crystals are recycled. The condensed water enters the comprehensive detection module 2 for detection, and is analyzed and decided by the central control system. If it is unqualified, the water body is sent back to the evaporation crystallization module through the pipeline for repeated evaporation, and if it is qualified, it can be used.

[0058] Further, please refer to Figure 2The physical adsorption module comprises a filter tank, and the tail water of the farmland is adsorbed, deodorized and preliminarily purified through an activated carbon filter, and water-insoluble impurities are filtered. The activated carbon has the characteristics of low price and easy availability, and has high adsorption efficiency and does not cause secondary pollution. The tail water electrolysis module comprises an electrolytic tank, and a multi-electrode electrolysis device 4 is fixed on the electrolytic tank through bolts. The tail water of the farmland after filtration and adsorption is subjected to electrolytic treatment through the multi-electrode electrolysis device 4 to remove most of the organic matter and heavy metal ions. The biological purification module comprises an adjusting tank, a first wetland unit and a second wetland unit arranged in sequence. The adjusting tank is used for adjusting the water quantity and balancing the water quality, and water is continuously and quantitatively pumped to the wetland unit through a water pump at a fixed time. The first wetland unit and the second wetland unit respectively perform primary and secondary purification on residual organic matter, heavy metal ions and part of inorganic salts in the tail water of the farmland. The first wetland unit selects coarse sand (particle size 1 mm) as an adsorption substrate, and the second wetland unit selects waste brick blocks (particle size 10-30 mm) as an adsorption substrate, and special salt-tolerant and alkali-tolerant wetland plants such as reed and cattail are planted in the wetland units, which are crushed after maturation and used for straw returning to the field.

[0059] The physical adsorption module is used for preliminary adsorption to remove resin, fallen leaves and other impurities, thereby reducing the pollution degree of the water body entering the electrolytic tank and protecting the multi-electrode electrolysis device 4 from being affected by excessive impurities. The water body subjected to electrolytic treatment is purified by aquatic plants in the first wetland unit and the second wetland unit, and coarse sand and waste brick blocks are used as adsorption substrates. The optimal particle size is determined through tests, and the primary purification of the water body is realized through strong salt-tolerant and strong adsorption plants such as reed and cattail.

[0060] Further, the arid region saline-alkali farmland tail water grading purification system is powered by a solar photovoltaic panel, and the solar photovoltaic panel is further connected with a voltage conversion device and a storage power supply, and is connected with all electrical equipment of the system through an electric lead and supplies power for the electrical equipment. The electrolytic tank is sawtooth-shaped, the multi-electrode electrolysis device 4 is composed of multiple groups of series-connected cathode and anode electrode devices, the cathode material is graphite, and the anode material is a Fe-Al mixed plate (the ratio is 1:1), and the plate spacing is 100 mm. The cathode material and the anode material are respectively connected in series through copper wires, and there are 6 pairs of electrodes. Each pair of electrodes is connected with the solar photovoltaic panel through a copper wire. The current adjustment period of the multi-electrode electrolysis device 4 is 1 h, and the current density control interval is 10-100 mA / cm 2 , and the variable range is ±10 mA / cm 2 .

[0061] The cathode material is selected from stable and green graphite material, and the Al electrode in the selected Fe-Al mixed electrode can generate Al(OH)3 with coagulation effect and adsorb divalent iron ions in the tail water, and the generated Fe(OH)3 can adsorb colloidal particles in the tail water to produce precipitation. At the same time, the pulse electrolysis method is set to meet the electrolytic threshold of various heavy metal ions such as chromium, cadmium, lead, mercury, copper and zinc in the tail water to the electrolysis device, so as to obtain the maximum electrolysis efficiency.

[0062] Further, the tail water heating module includes a solar heat collecting vacuum tube for heating the high-salt-content farmland tail water purified by the preliminary purification treatment system; the evaporation crystallization module includes a flash tank and a salt drying box, the farmland tail water treated by the tail water heating module is heated and evaporated again through the flash tank, and the inorganic salt evaporated and crystallized is collected through the salt drying box; the tail water condensing module includes a circulating condenser for condensing the water vapor of the flash tank. The solar heat collecting vacuum tube is made of quartz and has a heat absorbing coating on the surface, and an adjustable support is arranged below to adjust the heating angle in real time according to different geographical positions and seasonal rules; the flash tank realizes efficient evaporation crystallization of the farmland tail water by adjusting the vacuum degree and the temperature of the farmland tail water at the inlet; and the circulating condenser is a multi-tube-pass arranged shell-and-tube circulating condenser.

[0063] In use, the solar heat collecting vacuum tube preliminarily heats the tail water, reducing the internal heating time, and the heated water enters the flash tank through the pipeline, the flash tank realizes efficient evaporation of the tail water by controlling the water inlet temperature and the vacuum degree, the water vapor after evaporation is introduced into the circulating condenser, the remaining salt is collected in the salt drying box, which can be further extracted and recycled, and the water vapor is liquefied into liquid water after condensation.

[0064] Further, the tail water detection system includes a water storage tank, the salinity detection module is a salinity detector 1, the water quality detection module is a water quality detector 2, and the toxicity detection module is a toxicity sensor 3, the salinity detector 1, the water quality detector 2 and the toxicity sensor 3 are fixed on the inside of the water storage tank by bolts; the preliminary purification treatment system further includes a water outlet tank, the comprehensive detection module 1 is installed on the inside of the water outlet tank, and the comprehensive detection module 1 includes the water quality detector 2 and the toxicity sensor 3; the tail water treated by the deep purification treatment system enters a clean water tank, the comprehensive detection module 2 is installed on the inside of the clean water tank and includes the salinity detector 1; the salinity detector 1, the water quality detector 2 and the toxicity sensor 3 are respectively used for detecting the salinity, the water quality and the toxicity of the tail water.

[0065] The related equipment and instruments designed in the application can be purchased in the market, and the model is selected according to the system scale, and the connection or installation mode between all the equipment is not mentioned in detail in the application, and is installed or connected according to the conventional mode. The toxicity sensor adopts a biological toxicity sensor based on microbial electricity generation, and its working principle is to convert the chemical energy in the biological oxidation process of organic pollutants in the water body into an electric signal by using microbial extracellular respiration. Toxicity unit (TU) is an evaluation index for identifying and evaluating the toxicity of farmland tail water, which represents the size of the toxicity, and its specific standard refers to the toxicity standard of wastewater discharge in the United States. The toxicity standard is adjusted in real time according to the demand for purified water.

[0066] Referring to Figure 3 The application also provides a purification method of the arid saline farmland tail water grading purification system, comprising:

[0067] Step one, detecting the salinity, water quality and toxicity data of the farmland tail water entering the tail water detection system through the salinity detection module, the water quality detection module and the toxicity detection module;

[0068] Step two, the central control system records the salinity, water quality and toxicity data of the farmland tail water entering the tail water detection system, and compares them with the standard values in the database, and then feeds back to the monitoring feedback module for display; the central control system makes a decision according to the tail water detection comparison result, when the salinity or water quality or toxicity detection result is not over standard, no purification is needed, and it can be directly used, when any index is over standard, step three is carried out;

[0069] Step three, the farmland tail water is preliminarily purified by the physical adsorption module;

[0070] Step four, the farmland tail water is preliminarily purified by the tail water electrolysis module and the biological purification module in turn, and the preliminarily purified farmland tail water is detected again by the comprehensive detection module 1;

[0071] Step five, the central control system records the water quality and toxicity data of the farmland tail water entering the comprehensive detection module 1, and compares them with the standard values in the database, and then feeds back to the monitoring feedback module for display, and makes a decision according to the tail water detection comparison result, when the water quality or toxicity detection result is not over standard, step six is carried out, when any index is over standard, step four is carried out again;

[0072] Step six, the farmland tail water after preliminary purification is heated by the tail water heating module;

[0073] Step seven, the heated water treated by the tail water heating module is evaporated and crystallized by the evaporation crystallization module, and the water vapor in the evaporation crystallization module is condensed and liquefied by the tail water condensation module, so as to realize the deep purification of the farmland tail water, and the tail water after deep purification treatment is detected again by the comprehensive detection module 2.

[0074] Step eight, the central control system records the salinity data of the farmland tail water entering the comprehensive detection module 2, and compares it with the standard value in the database, and then feeds back to the monitoring feedback module for display, and makes a decision according to the tail water detection comparison result, when the salinity detection result is not over standard, the purification is completed, otherwise, step seven is performed again.

[0075] The application also provides a computer device comprising a memory, a processor and a computer program, wherein the computer program is stored in the memory and can be run on the processor, and wherein the processor implements the steps of the purification method of the arid saline farmland tail water grading purification system when the computer program is executed. The full-process automatic control of the system operation is realized by the computer device, which greatly saves manpower and improves work efficiency.

[0076] Specific use method:

[0077] After selecting the construction site, performing necessary flattening, excavation and supporting civil engineering construction, installing instruments and equipment at the corresponding positions, such as installing the salinity detector 1, the water quality detector 2 and the toxicity sensor 3 in the water storage tank, installing the water quality detector 2 and the toxicity sensor 3 in the water outlet tank, installing the salinity detector 1 in the purified water tank, installing the electrolytic tank and the multi-electrode electrolysis device 4 in the tail water electrolysis module, installing the solar heat collecting vacuum tube in the tail water heating module, installing the flash tank in the evaporation crystallization module, installing the circulating condenser in the tail water condensation module, and connecting them through wire, pipeline and other connecting structures, an integrated arid saline farmland tail water grading purification system is formed.

[0078] The water inlet is detected in the water storage tank, and then the whole system is operated according to the purification method of the arid saline farmland tail water grading purification system, and the whole process is controlled by a computer program. Of course, manual control can also be used when it is not convenient, such as determining the step of the system according to the feedback of the monitoring feedback module.

[0079] Although the embodiments of the application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the application, and the scope of the application is defined by the appended claims and their equivalents.

Claims

1. A hierarchical purification system for tail water in saline-alkali farmland in arid areas, characterized in that, The tail water detection system, the preliminary purification treatment system and the deep purification treatment system are sequentially arranged. The tail water detection system comprises a salinity detection module, a water quality detection module and a toxicity detection module, and is used for detecting the salinity, water quality and toxicity of the tail water. The preliminary purification treatment system comprises a physical adsorption module, a tail water electrolysis module and a biological purification module which are sequentially arranged and used for preliminary purification treatment of the tail water. The physical adsorption module comprises a filter tank, and the tail water is adsorbed, deodorized and preliminarily purified through an activated carbon filter, and the water-insoluble impurities are filtered. The tail water electrolysis module comprises an electrolytic tank, and a multi-electrode electrolysis device (4) is fixed on the electrolytic tank through bolts. The electrolytic tank is sawtooth-shaped, and the multi-electrode electrolysis device (4) is composed of a plurality of series-connected cathode and anode electrode devices. The current regulation period of the multi-electrode electrolysis device (4) is 1 h, and the current density control interval is 10-100 mA / cm 2 , with a variation range of ±10 mA / cm 2 ; The biological purification module comprises a regulating tank, a first wetland unit and a second wetland unit which are sequentially arranged. The deep purification treatment system comprises a tail water heating module, an evaporation crystallization module and a tail water condensation module which are sequentially arranged and used for further treatment of the tail water. The tail water detection system, the preliminary purification treatment system and the deep purification treatment system are electrically connected with the central control system. The purification method of the purification system comprises the following steps. Step one, detecting the salinity, water quality and toxicity data of the tail water entering the tail water detection system through the salinity detection module, the water quality detection module and the toxicity detection module. Step two, recording the salinity, water quality and toxicity data of the tail water entering the tail water detection system by the central control system, comparing the data with the standard values in the database, and then feeding back to the monitoring feedback module for display. Step three, preliminarily purifying the tail water through the physical adsorption module. Step four, sequentially purifying the tail water through the tail water electrolysis module and the biological purification module, and detecting the preliminarily purified tail water again through the comprehensive detection module 1. Step five, the central control system records the water quality and toxicity data of the farmland tail water entering the comprehensive detection module 1, compares them with the standard values in the database, and then feeds back to the monitoring feedback module for display, and makes decisions according to the tail water detection comparison results. When the water quality and toxicity detection results are all within the standard, step six is performed; when any index exceeds the standard, step four is performed again; Step six, the farmland tail water is heated and treated by the tail water heating module; Step seven, the heated water treated by the tail water heating module is evaporated and crystallized by the evaporation crystallization module, and the water vapor of the evaporation crystallization module is condensed and liquefied by the tail water condensation module, realizing deep purification treatment of the farmland tail water. The deep purification treated tail water is detected again by the comprehensive detection module 2; Step eight, the central control system records the salinity data of the farmland tail water entering the comprehensive detection module 2, compares them with the standard values in the database, and then feeds back to the monitoring feedback module for display, and makes decisions according to the tail water detection comparison results. When the salinity detection result is not over standard, the purification is completed; when the salinity is over standard, step seven is performed again.

2. The farmland tail water grading purification system in arid saline-alkali area according to claim 1, characterized in that: The adjusting tank is used to adjust the water quantity and balance the water quality, and the water pump is used to continuously and quantitatively supply water to the wetland unit; the first and second wetland units are used to purify the residual organic matter, heavy metal ions and part of inorganic salt in the farmland tail water.

3. The farmland tail water grading purification system in arid saline-alkali area according to claim 2, characterized in that: The farmland tail water grading purification system in arid saline-alkali area is powered by a solar photovoltaic panel; Each cathode material and anode material is connected in series by copper wire, and there are 6 pairs in total. Each pair of electrodes is connected to the solar photovoltaic panel by copper wire.

4. The farmland tail water grading purification system in arid saline-alkali area according to claim 1, characterized in that: The tail water heating module includes a solar heat collecting vacuum tube, which is used to heat the high-salinity farmland tail water purified by the preliminary purification treatment system; The evaporation crystallization module includes a flash tank and a salt drying box, which are used to reheat and evaporate the farmland tail water treated by the tail water heating module, and collect the inorganic salt evaporated and crystallized by the salt drying box; The tail water condensation module includes a circulating condenser, which is used to condense the evaporated water vapor of the flash tank.

5. The farmland tail water grading purification system in arid saline-alkali area according to claim 4, characterized in that: The solar heat collecting vacuum tube is made of quartz and has a heat absorbing coating on its surface. An adjustable support is provided below the tube to adjust the heating angle in real time according to different geographical positions and seasonal rules; The flash tank realizes efficient evaporation crystallization of the farmland tail water by adjusting its vacuum degree and the temperature of the farmland tail water at the inlet; The circulating condenser is a multi-tube-pass arranged tube-shell type circulating condenser.

6. The farmland tail water grading purification system in arid saline-alkali area according to claim 1, characterized in that: The tail water detection system comprises a water storage pool, the salinity detection module is a salinity detector (1), the water quality detection module is a water quality detector (2), and the toxicity detection module is a toxicity sensor (3); the salinity detector (1), the water quality detector (2) and the toxicity sensor (3) are fixed on the inner side of the water storage pool by bolts; The preliminary purification treatment system further comprises a water outlet pool, the comprehensive detection module 1 is installed in the water outlet pool, and the comprehensive detection module 1 comprises the water quality detector (2) and the toxicity sensor (3); The tail water treated by the deep purification treatment system enters a clean water pool, the comprehensive detection module 2 is installed in the clean water pool, and the comprehensive detection module 2 comprises the salinity detector (1); The salinity detector (1), the water quality detector (2) and the toxicity sensor (3) are respectively used for detecting the salinity, the water quality and the toxicity of the tail water.

7. A computer arrangement comprising a memory, a processor and a computer program, said computer program being stored on said memory and being executable on said processor, characterized in that, The processor executes the computer program to realize the steps of the purification method of the purification system according to claim 1.

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