Multi-state transformation system and comprehensive management method of nitrogen fertilizer in farmland drainage water

Abstract

The application discloses a multi-state conversion system and a comprehensive management method for nitrogen fertilizer in farmland drainage water, and belongs to the technical field of farmland management. The application discloses a multi-state conversion system and a comprehensive management method for nitrogen fertilizer in farmland drainage water, and belongs to the technical field of farmland management. The application discloses a multi-state conversion system and a comprehensive management method for nitrogen fertilizer in farmland drainage water, and belongs to the technical field of farmland management. The application discloses a multi-state conversion system and a comprehensive management method for nitrogen fertilizer in farmland drainage water, and belongs to the technical field of farmland management. The application discloses a multi-state conversion system and a comprehensive management method for nitrogen fertilizer in farmland drainage water, and belongs to the technical field of farmland management. The application discloses a multi-state conversion system and a comprehensive management method for nitrogen fertilizer in farmland drainage water, and belongs to the technical field of farmland management. The application discloses a multi-state conversion system and a comprehensive management method for nitrogen fertilizer in farmland drainage water, and belongs to the technical field of farmland management. The application discloses a multi-state conversion system and a comprehensive management method for nitrogen fertilizer in farmland drainage water, and belongs to the technical field of farmland management. The application discloses a multi-state conversion system and a comprehensive management method for nitrogen fertilizer in farmland drainage water, and belongs to the technical field of farmland management. The application discloses a multi-state conversion system and a comprehensive management method for nitrogen fertilizer in farmland drainage water, and belongs to the technical field of farmland management. The application discloses a multi-state conversion system and a comprehensive management method for nitrogen fertilizer in farmland drainage water, and belongs to the technical field of farmland management. The application discloses a multi-state conversion system and a comprehensive management method for nitrogen fertilizer in farmland drainage water, and belongs to the technical field of farmland management. The application discloses a multi-state conversion system and a comprehensive management method for nitrogen fertilizer in farmland drainage water, and belongs to the technical field of farmland management. The application discloses a multi-state conversion system and a comprehensive management method for nitrogen

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of agricultural non-point source pollution control and water ecological environment protection, and relates to the recycling and deep treatment of nitrogen fertilizer in farmland runoff, in particular to a multi-state conversion system and a multi-effect utilization and comprehensive control method of nitrogen fertilizer in farmland runoff. BACKGROUND

[0002] Nitrogen is not only an important nutrient element for protein composition in crops, but also a main component of chlorophyll in crops. Meanwhile, nitrogen plays an irreplaceable role in stem and leaf growth, leaf thickening and greening, flower bud differentiation, flowering and fruit setting of crops. Therefore, nitrogen is the most important nutrient element for improving crop yield, directly affects the growth of crops and the formation of final yield, and is the largest amount and highest frequency of fertilizer used in agricultural production.

[0003] Farmland runoff is water body produced by farmland accumulated water discharge or rainfall runoff in the process of agricultural production. Due to the use of nitrogen fertilizer in the process of agricultural production, there is more residual nitrogen in farmland. After water runoff, nitrogen will be carried into the river, causing water eutrophication. Therefore, purifying farmland runoff can improve the water environment and bring considerable economic and environmental benefits, which is of great significance.

[0004] At present, the common farmland runoff control methods mainly include plant buffer zone, artificial wetland system, multi-pond system, ecological ditch system, etc. The above methods utilize the absorption and interception capacity of vegetation to soil nitrogen to achieve the interception and filtration of non-point source pollutants. However, the above methods cause the waste of nitrogen, and also increase the difficulty of subsequent treatment. How to recycle and reuse a large amount of nitrogen in farmland runoff has become an urgent problem to be solved at present.

[0005] The nitrogen element that can be absorbed by crop roots mainly includes ammonium nitrogen and nitrate nitrogen. All the nitrogen elements in the soil or in any form must be converted into ammonium nitrogen or nitrate nitrogen. Therefore, the commonly used nitrogen fertilizer mainly includes ammonium nitrogen fertilizer and nitrate nitrogen fertilizer. The ammonium nitrogen fertilizer refers to the nitrogen fertilizer in the form of ammonium or ammonia, such as ammonium bicarbonate, ammonium sulfate, ammonium chloride and the like, which belongs to acid or physiological acid fertilizer. Long-term use of such fertilizer can cause soil acidification. The nitrate nitrogen fertilizer refers to the nitrogen fertilizer in the form of nitrate, such as ammonium nitrate, sodium nitrate, calcium nitrate and the like, which belongs to alkaline or physiological alkaline fertilizer. The pH of the soil after fertilization is prone to rise. In addition, the nutrient of the nitrate nitrogen fertilizer can be directly and quickly absorbed by crops, but its fertilizer efficiency period is relatively short and is prone to loss, belonging to the type of quick-acting nitrogen fertilizer. The nutrient release period of the ammonium nitrogen fertilizer is relatively long, belonging to the type of relatively long-acting nitrogen fertilizer, but its absorption speed and safety are weaker than those of the nitrate nitrogen fertilizer. Therefore, when using nitrogen fertilizer for crops, compared with single nitrogen fertilizer, the use of nitrate nitrogen fertilizer and ammonium nitrogen fertilizer together can often make crops obtain a higher production rate and yield, thereby playing the best effect of nitrogen supplement on crops in the field.

[0006] However, the acid fertilizer such as ammonium nitrogen fertilizer is not suitable for being mixed with the alkaline fertilizer such as nitrate nitrogen fertilizer, because the mixed application will increase the loss and volatilization of nitrogen, thereby losing or reducing the fertilizer efficiency. In addition, most farmers have only a vague understanding of the classification of nitrogen fertilizer, the characteristics of fertilizer, the best use range and method of different types of nitrogen fertilizer, and the like. Blind fertilization not only cannot achieve the best fertilization effect, but also causes the consequences of more money spent on fertilizer and more waste of fertilizer. In severe cases, it can also cause crop fertilizer damage. Therefore, how to simply, conveniently, scientifically and effectively apply nitrogen fertilizer is very important. SUMMARY

[0007] In order to solve the above problems, the present application provides a multi-state conversion system and a comprehensive management method for nitrogen fertilizer in farmland runoff water. The ammonium nitrogen fertilizer treatment unit, the nitrate nitrogen fertilizer treatment unit and the water-soluble nitrogen fertilizer regulator are arranged, and the nitrogen multi-effect utilization and comprehensive management of four different scenes are carried out according to the amount of runoff water and the type of nitrogen fertilizer. For conventional runoff water, the ammonium nitrogen fertilizer treatment unit can convert the ammonium nitrogen fertilizer in the farmland runoff water into nitrate nitrogen fertilizer, and the nitrate nitrogen fertilizer treatment unit can convert the nitrate nitrogen fertilizer in the farmland runoff water into ammonium nitrogen fertilizer. After being treated by the water-soluble nitrogen fertilizer regulator, it can be used as water-soluble nitrogen fertilizer for farmland. After the total nitrogen concentration of the farmland runoff water meets the surface water environmental quality standard after multiple cycles, it can be discharged to the surrounding river, thereby realizing the combined application of ammonium nitrogen fertilizer and nitrate nitrogen fertilizer and the purification treatment of temporary farmland runoff water. For excessive runoff water, the ammonium nitrogen fertilizer treatment unit and the nitrate nitrogen fertilizer treatment unit are used in combination to convert the ammonium nitrogen fertilizer in the farmland runoff water into nitrogen gas, and the nitrate nitrogen fertilizer treatment unit can directly convert the nitrate nitrogen fertilizer in the farmland runoff water into nitrogen gas. The denitrification tail water can be discharged to the surrounding river, thereby realizing the purification treatment of persistent farmland runoff water.

[0008] In order to achieve the above object, the present application adopts the following technical solutions:

[0009] The present application first provides a multi-effect utilization and comprehensive management method for nitrogen fertilizer in farmland drainage, which comprises a multi-state conversion system for nitrogen fertilizer in farmland drainage, and the multi-effect utilization and comprehensive management of nitrogen in four different scenarios of farmland drainage according to the amount of drainage and the type of nitrogen fertilizer, wherein the four different scenarios are ammonium nitrogen fertilizer conventional drainage, nitrate nitrogen fertilizer conventional drainage, ammonium nitrogen fertilizer excessive drainage and nitrate nitrogen fertilizer excessive drainage, the conventional drainage refers to farmland drainage with a drainage amount not greater than the volume of water-soluble nitrogen fertilizer regulator, and the excessive drainage refers to farmland drainage with a drainage amount greater than the volume of water-soluble nitrogen fertilizer regulator.

[0010] As a preferred scheme of the present application, for the ammonium nitrogen fertilizer conventional drainage, the farmland drainage is sent to an aerobic tank for nitrification reaction, and the operation process comprises water inlet, aeration, sedimentation and water outlet; the mud-water mixture is realized in the aerobic tank through an aerator, the DO is controlled at 2.0-3.0 mg / L, the pH is controlled at 7.50-8.00, and the temperature is controlled at 25-30℃; when the ammonia nitrogen concentration is 0 mg / L, the nitrification reaction is ended, the aeration is stopped, and the water outlet is started after 10-30 min of sedimentation; the nitrate nitrogen tail water is sent to a water-soluble nitrogen fertilizer regulator, the pH regulator is controlled by PLC to adjust the pH of the water-soluble nitrogen fertilizer to be close to the pH of the local healthy farmland soil, and the jet mixer is controlled to mix and oxygenate, so that the DO of the water-soluble nitrogen fertilizer is not less than 0.5 mg / L, and the generated water-soluble nitrogen fertilizer is re-sent to the farmland.

[0011] As a preferred scheme of the present application, for the nitrate nitrogen fertilizer conventional drainage, the farmland drainage is sent to an anoxic tank for nitrate dissimilatory reduction to ammonium reaction, and the operation process comprises water inlet, stirring, sedimentation and water outlet; the mud-water mixture is realized in the anoxic tank through a stirrer, the molar concentration ratio of ferrous ion to nitrate nitrogen is adjusted and controlled at 1.5-6.5 by adding ferrous sulfate, the temperature is controlled at 30-37℃, and the pH is controlled at 8.50; when the nitrate nitrogen concentration is 0 mg / L, the nitrate dissimilatory reduction to ammonium reaction is ended, the stirring is stopped, and the water outlet is started after 10-30 min of sedimentation; the ammonia nitrogen tail water is sent to a water-soluble nitrogen fertilizer regulator, the pH regulator is controlled by PLC to adjust the pH of the water-soluble nitrogen fertilizer to be close to the pH of the local healthy farmland soil, and the jet mixer is controlled to mix and oxygenate, so that the DO of the water-soluble nitrogen fertilizer is not less than 0.5 mg / L, and the generated water-soluble nitrogen fertilizer is re-sent to the farmland.

[0012] As a preferred scheme of the present application, for excess ammonium nitrogen fertilizer runoff, the farmland runoff is equally divided into two streams, one of which enters the aerobic tank to undergo nitrification reaction, the operation process including water inlet, aeration, sedimentation and water discharge, the mud-water mixture is realized in the aerobic tank through aerator, DO is controlled at 2.0-3.0 mg / L, pH is controlled at 7.50-8.00, and temperature is controlled at 25-30℃; when the ammonia nitrogen concentration is 0 mg / L, the nitrification reaction ends, aeration is stopped, and after 10-30 min of sedimentation, water discharge is started, and the nitrification tail water is sent to the water-soluble nitrogen fertilizer regulator for temporary storage; the other stream of farmland runoff and the nitrification tail water temporarily stored in the water-soluble nitrogen fertilizer regulator enter the anoxic tank in equal volume to undergo short-range nitrate dissimilation into ammonium coupled with anaerobic ammonia oxidation reaction, the operation process including water inlet, stirring, sedimentation and water discharge, the mud-water mixture is realized in the anoxic tank through stirrer, the carbon-nitrogen ratio is adjusted by adding sodium acetate and controlled at 0.43-0.75, temperature is controlled at 30-37℃, and pH is controlled at 7.27-7.29; when the total nitrogen concentration is lower than 2.0 mg / L, the short-range nitrate dissimilation into ammonium coupled with anaerobic ammonia oxidation reaction ends, stirring is stopped, and after 10-30 min of sedimentation, water discharge is started, and the denitrification tail water is discharged to the surrounding river.

[0013] As a preferred scheme of the present application, for excess ammonium nitrogen fertilizer runoff, the farmland runoff is sent to the anoxic tank to undergo nitrate dissimilation into ammonium coupled with anaerobic ammonia oxidation reaction, the operation process including water inlet, stirring, sedimentation and water discharge; the mud-water mixture is realized in the anoxic tank through stirrer, the carbon-nitrogen ratio is adjusted by adding sodium acetate and controlled at 1.07-1.67, temperature is controlled at 30-37℃, and pH is controlled at 7.07-7.10; when the total nitrogen concentration is lower than 2.0 mg / L, the nitrate dissimilation into ammonium coupled with anaerobic ammonia oxidation reaction ends, stirring is stopped, and after 10-30 min of sedimentation, water discharge is started, and the denitrification tail water is discharged to the surrounding river.

[0014] The present application also provides a multi-state conversion system for nitrogen fertilizer in farmland runoff, the multi-state conversion system comprising an ammonium nitrogen fertilizer treatment unit, a nitrate nitrogen fertilizer treatment unit and a water-soluble nitrogen fertilizer regulator;

[0015] The ammonium nitrogen fertilizer treatment unit is provided with an aerobic tank, and the number of the aerobic tank is not less than three; each aerobic tank is inoculated with nitrification sludge taken from a municipal sewage plant, the sludge concentration is controlled at 3000-5000 mg / L, and a water quality determinator, a farmland runoff self-control water inlet, an aerator and a tail water pump are arranged;

[0016] The nitrate nitrogen fertilizer treatment unit is provided with an anoxic tank, and the number of the anoxic tank is not less than three; each anoxic tank is inoculated with anaerobic ammonia oxidation biofilm sludge or granular sludge, the filling ratio is controlled at 30%-70%, and a stirrer, a water quality determinator, a farmland runoff self-control water inlet and a tail water pump are arranged; the nitrate nitrogen fertilizer treatment unit is also provided with an ammonium nitrogen self-control valve and a denitrification tail water self-control valve.

[0017] The water-soluble nitrogen fertilizer regulator is provided with a nitrate nitrogen fertilizer inlet, an ammonium nitrogen fertilizer inlet, a jet mixer, a water quality regulator, a water-soluble nitrogen fertilizer outlet, a PLC, a water-soluble nitrogen fertilizer pump, a water-soluble nitrogen fertilizer automatic control valve and a nitrate nitrogen fertilizer automatic control valve.

[0018] As a preferred scheme of the present application, the parameters of the water quality tester in the aerobic tank include temperature, pH, DO and ammonia nitrogen.

[0019] As a preferred scheme of the present application, the parameters of the water quality tester in the anoxic tank include temperature, pH, total iron, COD, nitrate nitrogen and total nitrogen.

[0020] As a preferred scheme of the present application, the PLC controls the pH and DO adjustment of the water-soluble nitrogen fertilizer in the water-soluble nitrogen fertilizer regulator by the water quality regulator and the jet mixer.

[0021] As a preferred scheme of the present application, a water quality tester and a farmland drainage pump are arranged at the farmland drainage outlet, the parameters of the water quality tester include ammonia nitrogen, nitrate nitrogen and total nitrogen, and the number of the farmland drainage pumps is three.

[0022] Compared with the prior art, the present application has the following beneficial effects:

[0023] 1) The present application successfully realizes the mutual conversion, recycling, compound fertilization and total nitrogen removal of ammonium nitrogen fertilizer and nitrate nitrogen fertilizer in farmland drainage by arranging the ammonium nitrogen fertilizer treatment unit, the nitrate nitrogen fertilizer treatment unit and the water-soluble nitrogen fertilizer regulator. This not only helps the deep denitrification of farmland drainage, but also optimizes the fertilization method, achieves the purpose of light and simple fertilization, cost reduction and benefit increase through "one fertilizer for two purposes", and further comprehensively implements the farmland management goal of "drainage water not directly discharged, fertilizer and water not entering the river, and nutrient recycling".

[0024] 2) The present application also combines the drainage amount to realize the nitrogen multi-effect utilization and comprehensive management of four different scenes of farmland drainage, thereby effectively dealing with different types of farmland drainage such as irrigation drainage, short-time rainfall drainage and continuous rainfall drainage. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is a flow chart of the multi-effect utilization and comprehensive management of nitrogen fertilizer in farmland drainage.

[0026] Figure 2 is a structural diagram of the multi-state conversion system of nitrogen fertilizer in farmland drainage.

[0027] In the figure, 1. ammonium nitrogen fertilizer treatment unit; 1-1. first aerobic tank; 1-2. second aerobic tank; 1-3. third aerobic tank; 1-4. first water quality measuring instrument; 1-5. second water quality measuring instrument; 1-6. third water quality measuring instrument; 1-7. first farmland backwater automatic control water inlet; 1-8. second farmland backwater automatic control water inlet; 1-9. third farmland backwater automatic control water inlet; 1-10. first aerator; 1-11. second aerator; 1-12. third aerator; 1-13. first tail water pump; 1-14. second tail water pump; 1-15. third tail water pump;

[0028] 2. nitrate nitrogen fertilizer treatment unit; 2-1. first anoxic tank; 2-2. second anoxic tank; 2-3. third anoxic tank; 2-4. first agitator; 2-5. second agitator; 2-6. third agitator; 2-7. fourth water quality measuring instrument; 2-8. fifth water quality measuring instrument; 2-9. sixth water quality measuring instrument; 2-10. fourth farmland backwater automatic control water inlet; 2-11. fifth farmland backwater automatic control water inlet; 2-12. sixth farmland backwater automatic control water inlet; 2-13. fourth tail water pump; 2-14. fifth tail water pump; 2-15. sixth tail water pump; 2-16. ammonium nitrogen fertilizer automatic control valve; 2-17. denitrification tail water automatic control valve;

[0029] 3. water-soluble nitrogen fertilizer regulator; 3-1. nitrate nitrogen fertilizer inlet; 3-2. ammonium nitrogen fertilizer inlet; 3-3. jet mixer; 3-4. water quality regulator; 3-5. water-soluble nitrogen fertilizer outlet; 3-6. PLC; 3-7. water-soluble nitrogen fertilizer pump; 3-8. water-soluble nitrogen fertilizer automatic control valve; 3-9. nitrate nitrogen fertilizer automatic control valve;

[0030] 4. farmland; 4-1. seventh water quality measuring instrument; 4-2. first farmland backwater pump; 4-3. second farmland backwater pump; 4-4. third farmland backwater pump;

[0031] 5. river channel. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with 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.

[0033] Reference Figure 1The present application first provides a multi-effect utilization and comprehensive management method of nitrogen fertilizer in farmland runoff. The total nitrogen concentration of the farmland runoff is determined by the seventh water quality detector arranged at the outlet of the farmland runoff, and whether the farmland runoff needs to be utilized and managed is determined accordingly. Since the farmland water area should meet the surface water environmental quality standard V, and the total nitrogen standard limit is 2.0 mg / L, when the total nitrogen concentration is not higher than 2.0 mg / L, the farmland runoff is discharged into the surrounding river, and when the total nitrogen concentration is higher than 2.0 mg / L, the nitrogen in the farmland runoff should be multi-effect utilized and comprehensively managed according to the method described in the present application. By arranging the multi-state conversion system of nitrogen fertilizer in the farmland runoff, and according to the runoff amount and the type of nitrogen fertilizer, the nitrogen in the farmland runoff is multi-effect utilized and comprehensively managed in four different scenarios. The farmland runoff with an amount not greater than the volume of the water-soluble nitrogen fertilizer regulator is defined as conventional runoff, such as irrigation runoff, temporary farmland runoff such as short-time rainfall runoff, etc. For the conventional runoff, it is further divided into ammonium nitrogen fertilizer conventional runoff and nitrate nitrogen fertilizer conventional runoff according to the type of nitrogen fertilizer contained: the ammonium nitrogen fertilizer conventional runoff enters the ammonium nitrogen fertilizer treatment unit, and nitrification reaction occurs in the aerobic tank, which can convert the ammonia nitrogen in the farmland runoff into nitrate nitrogen; while the nitrate nitrogen fertilizer conventional runoff enters the nitrate nitrogen fertilizer treatment unit, and dissimilatory nitrate reduction to ammonium (DNRA) reaction occurs in the anoxic tank, which can convert the nitrate nitrogen in the farmland runoff into ammonia nitrogen; the generated nitrate nitrogen tail water or ammonia nitrogen tail water can be used as water-soluble nitrogen fertilizer after being treated by the water-soluble nitrogen fertilizer regulator, and is recycled to the farmland, and after the total nitrogen concentration of the farmland runoff meets the surface water environmental quality standard, it can be discharged into the surrounding river, thereby realizing the combined application of ammonium nitrogen fertilizer and nitrate nitrogen fertilizer and the purification and management of temporary farmland runoff. The farmland runoff with an amount greater than the volume of the water-soluble nitrogen fertilizer regulator is defined as excessive runoff, such as continuous rainfall runoff and other persistent farmland runoff. For the excessive runoff, it is further divided into ammonium nitrogen fertilizer excessive runoff and nitrate nitrogen fertilizer excessive runoff according to the type of nitrogen fertilizer contained: the ammonium nitrogen fertilizer excessive runoff needs to be used in combination with the ammonium nitrogen fertilizer treatment unit and the nitrate nitrogen fertilizer treatment unit, wherein nitrification reaction occurs in the aerobic tank of the ammonium nitrogen fertilizer treatment unit, and short-range DNRA coupled with Anammox (short-range DNRA-Anammox) reaction occurs in the anoxic tank of the nitrate nitrogen fertilizer treatment unit, which can finally convert the ammonia nitrogen in the farmland runoff into nitrogen gas; while the nitrate nitrogen fertilizer excessive runoff directly enters the nitrate nitrogen fertilizer treatment unit, and DNRA coupled with Anammox (DNRA-Anammox) reaction occurs in the anoxic tank, which can convert the nitrate nitrogen in the farmland runoff into nitrogen gas; the denitrification tail water can be discharged into the surrounding river, thereby realizing the purification and management of persistent farmland runoff. Example 1

[0034] Referring to Figure 2 The application also provides a multi-state conversion system for nitrogen fertilizer in farmland drainage water, which comprises an ammonium nitrogen fertilizer treatment unit 1, a nitrate nitrogen fertilizer treatment unit 2 and a water-soluble nitrogen fertilizer regulator 3.

[0035] The ammonium nitrogen fertilizer treatment unit 1 is provided with a first aerobic tank 1-1, a second aerobic tank 1-2 and a third aerobic tank 1-3, and each of the aerobic tanks is inoculated with nitrifying sludge taken from a municipal sewage plant, and the sludge concentration is controlled at 3000-5000 mg / L.

[0036] The first aerobic tank 1-1 is provided with a first water quality tester 1-4, a first farmland drainage water automatic control water inlet 1-7, a first aerator 1-10 and a first tail water pump 1-13.

[0037] The second aerobic tank 1-2 is provided with a second water quality tester 1-5, a second farmland drainage water automatic control water inlet 1-8, a second aerator 1-11 and a second tail water pump 1-14.

[0038] The third aerobic tank 1-3 is provided with a third water quality tester 1-6, a third farmland drainage water automatic control water inlet 1-9, a third aerator 1-12 and a third tail water pump 1-15.

[0039] The parameters of the first water quality tester 1-4, the second water quality tester 1-5 and the third water quality tester 1-6 include temperature, pH, DO and ammonia nitrogen.

[0040] The nitrate nitrogen fertilizer treatment unit 2 is provided with a first anoxic tank 2-1, a second anoxic tank 2-2 and a third anoxic tank 2-3, and each of the anoxic tanks is inoculated with anaerobic ammonia oxidation biofilm sludge or granular sludge, and the filling ratio is controlled at 30%-70%; in addition, the nitrate nitrogen fertilizer treatment unit 2 is also provided with an ammonium nitrogen fertilizer automatic control valve 2-16 and a denitrification tail water automatic control valve 2-17.

[0041] The first anoxic tank 2-1 is provided with a first stirrer 2-4, a fourth water quality tester 2-7, a fourth farmland drainage water automatic control water inlet 2-10 and a fourth tail water pump 2-13.

[0042] The second anoxic tank 2-2 is provided with a second stirrer 2-5, a fifth water quality tester 2-8, a fifth farmland drainage water automatic control water inlet 2-11 and a fifth tail water pump 2-14.

[0043] The third anoxic tank 2-3 is provided with a third stirrer 2-6, a sixth water quality tester 2-9, a sixth farmland drainage water automatic control water inlet 2-12 and a sixth tail water pump 2-15.

[0044] The parameters of the fourth water quality measuring instrument 2-7, the fifth water quality measuring instrument 2-8 and the sixth water quality measuring instrument 2-9 include temperature, pH, total iron, COD, nitrate nitrogen and total nitrogen.

[0045] The pipeline connected to the fourth tail water pump 2-13, the fifth tail water pump 2-14 and the sixth tail water pump 2-15 is connected to the water-soluble nitrogen fertilizer regulator 3 through the ammonium nitrogen fertilizer automatic control valve 2-16 on one side and connected to the river 5 through the denitrification tail water automatic control valve 2-17 on the other side.

[0046] The water-soluble nitrogen fertilizer regulator 3 is provided with a nitrate nitrogen fertilizer inlet 3-1, an ammonium nitrogen fertilizer inlet 3-2, a jet mixer 3-3, a water quality regulator 3-4, a water-soluble nitrogen fertilizer outlet 3-5, a PLC 3-6, a water-soluble nitrogen fertilizer pump 3-7, a water-soluble nitrogen fertilizer automatic control valve 3-8 and a nitrate nitrogen fertilizer automatic control valve 3-9. The PLC 3-6 controls the pH and DO adjustment of the water-soluble nitrogen fertilizer in the water-soluble nitrogen fertilizer regulator 3 by the water quality regulator 3-4 and the jet mixer 3-3. The water-soluble nitrogen fertilizer outlet 3-5 in the water-soluble nitrogen fertilizer regulator 3 is connected to the farmland 4 through the water-soluble nitrogen fertilizer pump 3-7 and the water-soluble nitrogen fertilizer automatic control valve 3-8, and connected to the nitrate nitrogen fertilizer treatment unit 2 through the water-soluble nitrogen fertilizer pump 3-7 and the nitrate nitrogen fertilizer automatic control valve 3-9.

[0047] The seventh water quality measuring instrument 4-1 and the first farmland tail water pump 4-2, the second farmland tail water pump 4-3 and the third farmland tail water pump 4-4 are arranged at the water outlet of the farmland 4. The parameters of the seventh water quality measuring instrument 4-1 include ammonia nitrogen, nitrate nitrogen and total nitrogen. The tail water of the farmland 4 is connected to the ammonium nitrogen fertilizer treatment unit 1 through the first farmland tail water pump 4-2, connected to the nitrate nitrogen fertilizer treatment unit 2 through the second farmland tail water pump 4-3, and connected to the river 5 through the third farmland tail water pump 4-4. Example 2

[0048] In the foregoing, the farmland tail water which needs to be utilized and managed is divided into four categories, i.e. ammonium nitrogen fertilizer conventional tail water, nitrate nitrogen fertilizer conventional tail water, ammonium nitrogen fertilizer excessive tail water and nitrate nitrogen fertilizer excessive tail water. The farmland tail water nitrogen multi-state conversion system provided in Example 1 is used to implement the farmland tail water nitrogen multi-effect utilization and comprehensive management method of the present application.

[0049] For conventional water withdrawal of ammonium nitrogen fertilizer, the farmland water is sent to the idle aerobic tank through the first farmland water pump and the first to third farmland water automatic control water inlet, and the nitrification reaction occurs in the aerobic tank. The operation process includes water inlet, aeration, sedimentation and drainage. The aeration can start after the water inlet is completed, or it can start simultaneously with the water inlet. The aerobic tank realizes mud-water mixing through the aerator, and a stirrer can also be additionally arranged to enhance the mud-water mixing effect; the DO is controlled at 2.0-3.0 mg / L, the pH is controlled at 7.50-8.00, and the temperature is controlled at 25-30℃. When the ammonia nitrogen concentration is 0 mg / L, the nitrification reaction is completed, the aeration is stopped, and the drainage is started after 10-30 min of sedimentation. The tail water is sent to the water-soluble nitrogen fertilizer regulator through the first to third tail water pumps, the pH regulator is controlled by the PLC to adjust the pH, so that the pH of the water-soluble nitrogen fertilizer is close to the pH of the local healthy farmland soil, and the jet mixer is controlled to mix and oxygenate, so that the DO of the water-soluble nitrogen fertilizer is not less than 0.5 mg / L. The generated water-soluble nitrogen fertilizer is sent back to the farmland through the water-soluble nitrogen fertilizer pump and the water-soluble nitrogen fertilizer automatic control valve.

[0050] Mechanism: Nitrifying bacteria include two bacterial groups of Ammonium Oxidizing Bacteria (AOB) and Nitrite Oxidizing Bacteria (NOB). The former can oxidize ammonia nitrogen to nitrite nitrogen, and the latter can further oxidize nitrite nitrogen to nitrate nitrogen. The process of AOB oxidizing ammonia nitrogen to nitrite nitrogen is called partial nitrification (PN) (NH4 + →NO2 - ) reaction, and the process of AOB and NOB jointly oxidizing ammonia nitrogen to nitrate nitrogen is called nitrification reaction (NH4 + →NO2 - →NO3 - ).

[0051] For conventional water withdrawal of nitrate nitrogen fertilizer, the farmland water is sent to the idle anoxic tank through the second farmland water pump and the fourth to sixth farmland water automatic control water inlets. The DNRA reaction occurs in the anoxic tank. The operation process includes water inlet, stirring, sedimentation and water outlet. The stirring can start simultaneously with the water inlet or after the water inlet. The anoxic tank realizes mud-water mixing through the stirrer. The molar concentration ratio of ferrous ions to nitrate nitrogen is adjusted by adding ferrous sulfate and controlled at 1.5-6.5. The temperature is controlled at 30-37℃, and the pH is controlled at 8.50. When the concentration of nitrate nitrogen is 0 mg / L, the DNRA reaction is ended, the stirring is stopped, and the water outlet is started after 10-30 min of sedimentation. The ammonia nitrogen tail water is sent to the water-soluble nitrogen fertilizer regulator through the fourth to sixth tail water pumps and the ammonium nitrogen fertilizer automatic control valve. The PLC controls the water quality regulator to adjust the pH, so that the pH of the water-soluble nitrogen fertilizer is close to the pH of the local healthy farmland soil. The jet mixer is controlled to mix and oxygenate, so that the DO of the water-soluble nitrogen fertilizer is not less than 0.5 mg / L. The generated water-soluble nitrogen fertilizer is sent back to the farmland through the water-soluble nitrogen fertilizer pump and the water-soluble nitrogen fertilizer automatic control valve.

[0052] Mechanism: Anammox bacteria have diverse metabolic pathways. In addition to the common Anammox reaction, they can also perform the DNRA reaction. The Anammox reaction refers to the reaction under anoxic conditions, with ammonia nitrogen as the electron donor and nitrite nitrogen as the electron acceptor, to generate nitrogen and part of nitrate nitrogen (NH4 + + NO2 - → N2 + NO3 - ); and the DNRA reaction is to take nitrate nitrogen as the electron acceptor, take nitrite nitrogen as the intermediate product, and finally generate ammonia nitrogen (NO3 - → NO2 - → NH4 + ). When the influent substrate is nitrate nitrogen and ferrous iron and the influent pH = 8.50, there is a large amount of ammonia nitrogen accumulation in the anammox reactor, and the DNRA reaction of Anammox bacteria is successfully realized.

[0053] For excess ammonium nitrogen fertilizer return water, the farmland return water (Q) is divided into two parts with equal volume. One part of farmland return water (50%Q) is sent to the idle aerobic tank through the first farmland return water pump and the first to third farmland return water automatic water inlet, and the nitrification reaction occurs in the aerobic tank. The nitrification treatment method is the same as the conventional return water of ammonium nitrogen fertilizer. After nitrification is completed, it enters the water-soluble nitrogen fertilizer regulator for temporary storage. The other part of farmland return water (50%Q) is sent to the idle anoxic tank through the fourth to sixth farmland return water automatic water inlets with equal volume of the nitrification tail water temporarily stored in the water-soluble nitrogen fertilizer regulator. The short-range DNRA-Anammox reaction occurs in the anoxic tank. The operation process includes water inlet, stirring, sedimentation and water outlet. The stirring can start simultaneously with the water inlet or after the water inlet is completed. The mud and water are mixed by the agitator, the carbon-nitrogen ratio is adjusted by adding sodium acetate and controlled at 0.43-0.75, the temperature is controlled at 30-37℃, the pH is controlled at 7.27-7.29, and the short-range DNRA-Anammox reaction is completed when the total nitrogen concentration is lower than 2.0 mg / L. The stirring is stopped, and the water outlet is started after 10-30 min of sedimentation. The denitrification tail water is discharged to the surrounding river through the fourth to sixth tail water pumps and the denitrification tail water automatic valve.

[0054] Mechanism: The biological reaction of Anammox bacteria for simultaneous removal of ammonia nitrogen and nitrate is short-range DNRA-Anammox reaction, which includes two steps: Anammox bacteria first use organic carbon source as reducing agent to convert nitrate nitrogen in raw water into intermediate product nitrite nitrogen (NO3 - →NO2 - ) through short-range DNRA reaction, and then convert ammonia nitrogen in raw water and generated nitrite nitrogen into nitrogen gas (NH4 + +NO2 - →N2+NO3 - ). Since AOB and NOB usually appear together in nitrification sludge, nitrification reaction is much easier to realize and control than short-range nitrification reaction. Obviously, Anammox bacteria can couple with nitrifying bacteria to realize the removal of ammonia nitrogen through more efficient, convenient and stable nitrification-short-range DNRA-Anammox process, thereby avoiding the complex work of washing NOB and enriching AOB required by short-range nitrification-anammox (PNA) process.

[0055] For the excess nitrate nitrogen fertilizer return water, the farmland return water is sent to the idle anoxic tank through the second farmland return water pump and the fourth to sixth farmland return water automatic control water inlets, the DNRA-Anammox reaction occurs in the anoxic tank, and the operation process comprises water inletting, stirring, sedimentation and water draining, wherein the stirring can be started simultaneously with the water inletting or started after the water inletting is completed. The anoxic tank realizes mud and water mixing through the stirrer, the carbon-nitrogen ratio is adjusted by adding sodium acetate and controlled at 1.07-1.67, the temperature is controlled at 30-37 DEG C, the pH is controlled at 7.07-7.10, the DNRA-Anammox reaction is ended when the total nitrogen concentration is lower than 2.0 mg / L, the stirring is stopped, the water draining is started after 10-30 min of sedimentation, and the denitrification tail water is drained to the surrounding river through the fourth to sixth tail water pumps and the denitrification tail water automatic control valves.

[0056] Mechanism: the biological reaction of the Anammox bacteria for removing nitrate is the DNRA-Anammox reaction, and the process comprises two steps: the Anammox bacteria first utilize the organic carbon source as a reducing agent, convert the nitrate nitrogen into an intermediate product nitrite nitrogen through the DNRA reaction, and continue to convert part of the nitrite nitrogen into ammonia nitrogen (NO3 - →0.5 NO2 - +0.5 NH4 + ), and then convert the generated ammonia nitrogen and nitrite nitrogen into nitrogen gas (NH4 + +NO2 - →N2+NO3 - ) through the Anammox reaction. Since the nitrite is converted into nitrogen gas through the anaerobic ammonia oxidation reaction in the second step, and the biological process does not need external organic matter, compared with the traditional denitrification reaction, the DNRA-Anammox reaction of the Anammox bacteria is obviously more economical and efficient.

[0057] In summary, the application not only can realize the deep denitrification of the farmland return water economically and efficiently, but also helps to optimize the nitrogen fertilizer application method, achieves the purpose of light and simple fertilization, cost reduction and benefit increase through "one fertilizer two uses", and further comprehensively implements the farmland management goal of "return water not direct discharge, fertilizer and water not into river, and nutrient reuse".

[0058] The above merely describes preferred embodiments of the present application, and is not intended to limit the present application in any form or in essence. It should be noted that those skilled in the art can make some improvements and supplements without departing from the method of the present application, and these improvements and supplements should also be considered as the protection scope of the present application. For those skilled in the art, some slight changes, modifications and equivalent changes made by using the disclosed technical content without departing from the spirit and scope of the present application are equivalent embodiments of the present application; meanwhile, any equivalent changes, modifications and evolution made according to the essential technology of the present application to the above embodiments are still within the scope of the technical solutions of the present application.

Claims

1. A method for multi-effect utilization and comprehensive management of nitrogen fertilizer in farmland drainage water, characterized in that, The multi-effect utilization and comprehensive management method comprises a multi-state conversion system of nitrogen fertilizer in farmland drainage water, the multi-state conversion system comprising an ammonium nitrogen fertilizer treatment unit, a nitrate nitrogen fertilizer treatment unit and a water-soluble nitrogen fertilizer regulator. The nitrogen multi-effect utilization and comprehensive management of the four different scenarios of farmland drainage water according to the drainage water amount and the type of nitrogen fertilizer, the four different scenarios being ammonium nitrogen fertilizer conventional drainage water, nitrate nitrogen fertilizer conventional drainage water, ammonium nitrogen fertilizer excessive drainage water and nitrate nitrogen fertilizer excessive drainage water; the nitrogen multi-effect utilization and comprehensive management being as follows: for the conventional drainage water of ammonium nitrogen fertilizer and nitrate nitrogen fertilizer, the ammonium nitrogen fertilizer treatment unit can convert the ammonium nitrogen fertilizer in the farmland drainage water into nitrate nitrogen fertilizer, and the nitrate nitrogen fertilizer treatment unit can convert the nitrate nitrogen fertilizer in the farmland drainage water into ammonium nitrogen fertilizer, which is treated by the water-soluble nitrogen fertilizer regulator and then reused as water-soluble nitrogen fertilizer in the farmland, and after multiple cycles, the total nitrogen concentration of the farmland drainage water meets the surface water environmental quality standard and can be discharged into the surrounding river; for the excessive drainage water of ammonium nitrogen fertilizer and nitrate nitrogen fertilizer, the ammonium nitrogen fertilizer treatment unit and the nitrate nitrogen fertilizer treatment unit are used in combination to convert the ammonium nitrogen fertilizer in the farmland drainage water into nitrogen gas, and the nitrate nitrogen fertilizer treatment unit can directly convert the nitrate nitrogen fertilizer in the farmland drainage water into nitrogen gas, and the denitrification tail water can be discharged into the surrounding river. The conventional drainage water is farmland drainage water with an amount not greater than the volume of the water-soluble nitrogen fertilizer regulator, and the excessive drainage water is farmland drainage water with an amount greater than the volume of the water-soluble nitrogen fertilizer regulator.

2. The multi-effect utilization and comprehensive management method of nitrogen fertilizer in farmland drainage water according to claim 1, characterized in that, For the conventional drainage water of ammonium nitrogen fertilizer, the farmland drainage water is sent to an aerobic tank for nitrification reaction, and the operation process comprises water inlet, aeration, sedimentation and water outlet; the aerobic tank realizes mud-water mixing through an aerator, the DO is controlled at 2.0-3.0 mg / L, the pH is controlled at 7.50-8.00, and the temperature is controlled at 25-30℃; when the ammonia nitrogen concentration is 0 mg / L, the nitrification reaction is ended, the aeration is stopped, and after 10-30 min of sedimentation, the water outlet is started; the nitrate nitrogen tail water is sent to the water-soluble nitrogen fertilizer regulator, the PLC controls the water quality regulator to adjust the pH, so that the pH of the water-soluble nitrogen fertilizer is close to the pH of the local healthy farmland soil, and controls the jet mixer to mix and oxygenate, so that the DO of the water-soluble nitrogen fertilizer is not less than 0.5 mg / L, and the generated water-soluble nitrogen fertilizer is sent back to the farmland.

3. The method for multi-effect utilization and comprehensive management of nitrogen fertilizer in farmland drainage water according to claim 1, characterized in that, For the conventional drainage water of nitrate nitrogen fertilizer, the farmland drainage water is sent to an anoxic tank for nitrate dissimilatory reduction to ammonium reaction, and the operation process comprises water inlet, stirring, sedimentation and water outlet; the anoxic tank realizes mud-water mixing through a stirrer, the molar concentration ratio of ferrous ion to nitrate nitrogen is adjusted by adding ferrous sulfate and controlled at 1.5-6.5, the temperature is controlled at 30-37℃, and the pH is controlled at 8.50; when the nitrate nitrogen concentration is 0 mg / L, the nitrate dissimilatory reduction to ammonium reaction is ended, the stirring is stopped, and after 10-30 min of sedimentation, the water outlet is started; the ammonia nitrogen tail water is sent to the water-soluble nitrogen fertilizer regulator, the adjustment method is the same as that of claim 2, and the generated water-soluble nitrogen fertilizer is sent back to the farmland.

4. The method for multi-effect utilization and comprehensive management of nitrogen fertilizer in farmland drainage water according to claim 1, characterized in that, For ammonium nitrogen fertilizer excess runoff, the farmland runoff is divided into two streams with equal volume. One stream of farmland runoff enters the aerobic tank for nitrification reaction, and the nitrification treatment method is the same as that of claim 2. After nitrification is completed, it enters the water-soluble nitrogen fertilizer regulator for temporary storage. The other stream of farmland runoff and the nitrification tail water temporarily stored in the water-soluble nitrogen fertilizer regulator enter the anoxic tank with equal volume for short-range nitrate dissimilatory reduction to ammonium coupled with anaerobic ammonia oxidation reaction. The operation process includes water inlet, stirring, sedimentation and water discharge. The sludge and water are mixed in the anoxic tank by a stirrer. The carbon-nitrogen ratio is adjusted by adding sodium acetate and controlled at 0.43-0.

75. The temperature is controlled at 30-37℃, and the pH is controlled at 7.27-7.

29. When the total nitrogen concentration is lower than 2.0 mg / L, the short-range nitrate dissimilatory reduction to ammonium coupled with anaerobic ammonia oxidation reaction is completed, the stirring is stopped, and the denitrification tail water is discharged after 10-30 min of sedimentation and then discharged to the surrounding river.

5. The method for multi-effect utilization and comprehensive management of nitrogen fertilizer in farmland drainage water according to claim 1, characterized in that, For nitrate nitrogen fertilizer excess runoff, the farmland runoff is sent to the anoxic tank for nitrate dissimilatory reduction to ammonium coupled with anaerobic ammonia oxidation reaction. The operation process includes water inlet, stirring, sedimentation and water discharge. The sludge and water are mixed in the anoxic tank by a stirrer. The carbon-nitrogen ratio is adjusted by adding sodium acetate and controlled at 1.07-1.

67. The temperature is controlled at 30-37℃, and the pH is controlled at 7.07-7.

10. When the total nitrogen concentration is lower than 2.0 mg / L, the nitrate dissimilatory reduction to ammonium coupled with anaerobic ammonia oxidation reaction is completed, the stirring is stopped, and the denitrification tail water is discharged after 10-30 min of sedimentation and then discharged to the surrounding river.

6. A multi-state conversion system of nitrogen fertilizer in farmland drainage water, characterized by, The multi-state transformation system comprises an ammonium nitrogen fertilizer treatment unit, a nitrate nitrogen fertilizer treatment unit and a water-soluble nitrogen fertilizer regulator. The ammonium nitrogen fertilizer treatment unit is provided with aerobic tanks, the number of which is not less than three. Each aerobic tank is inoculated with nitrification sludge taken from a municipal sewage plant, the sludge concentration is controlled at 3000-5000 mg / L, and a water quality tester, a farmland runoff automatic control water inlet, an aerator and a tail water pump are arranged. The nitrate nitrogen fertilizer treatment unit is provided with anoxic tanks, the number of which is not less than three. Each anoxic tank is inoculated with anaerobic ammonia oxidation biofilm sludge or granular sludge, the filling ratio is controlled at 30%-70%, and a stirrer, a water quality tester, a farmland runoff automatic control water inlet and a tail water pump are arranged. The nitrate nitrogen fertilizer treatment unit is further provided with an ammonium nitrogen fertilizer automatic control valve and a denitrification tail water automatic control valve. The water-soluble nitrogen fertilizer regulator is provided with a nitrate nitrogen fertilizer inlet, an ammonium nitrogen fertilizer inlet, a jet mixer, a water quality regulator, a water-soluble nitrogen fertilizer outlet, a PLC, a water-soluble nitrogen fertilizer pump, a water-soluble nitrogen fertilizer automatic control valve and a nitrate nitrogen fertilizer automatic control valve.

7. The multi-state conversion system of nitrogen fertilizer in farmland drainage water according to claim 6, characterized in that, The parameters of the water quality tester in the aerobic tank include temperature, pH, DO and ammonia nitrogen.

8. The multi-state conversion system of nitrogen fertilizer in farmland drainage water according to claim 6, characterized in that, The parameters of the water quality tester in the anoxic tank include temperature, pH, total iron, COD, nitrate nitrogen and total nitrogen.

9. The multi-state conversion system of nitrogen fertilizer in farmland drainage water according to claim 6, characterized in that, The PLC controls the water quality regulator and the jet mixer to adjust the pH and DO of the water-soluble nitrogen fertilizer in the water-soluble nitrogen fertilizer regulator.

10. The multi-state conversion system of nitrogen fertilizer in farmland drainage water according to claim 6, characterized in that, A water quality tester and a farmland runoff pump are arranged at the outlet of the farmland runoff. The parameters of the water quality tester include ammonia nitrogen, nitrate nitrogen and total nitrogen. The number of the farmland runoff pump is three.

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