Combined constructed wetland device for synchronous denitrification, dephosphorization and defluorination of agricultural irrigation and drainage

Abstract

The invention provides a combined constructed wetland device for synchronous denitrification, dephosphorization and defluorination of agricultural irrigation and drainage, and belongs to the technical field of surface water pollution control experiments. The experimental device comprises a water inlet overflow tank, an aerobic nitrification area, an anaerobic denitrification area, a filler adsorption area, a water outlet area, a water supply system, a sewage sampling system, a drainage system, a plant purification system and supporting legs, wherein the water supply system is connected with a water supply bucket through a silica gel hose and a peristaltic pump by virtue of the water inlet overflow tank; the sewage sampling system comprises a sampling port formed by connecting a pagoda head and a silica gel hose on one side of the device in a patch tapping manner; the drainage system comprises a water outlet, a silica gel hose and a polyethylene water storage barrel; the plant purification system comprises wetland plants contained in the floating baskets. According to the device, synchronous nitrogen, phosphorus and fluorine removal of agricultural irrigation drainage can be simulated, and stratified sampling can be realized. The experimental device is simple in structure, small in occupied area and suitable for being popularized in laboratories.

Description

Technical Field

[0001] The present invention relates to the technical field of surface water pollution control, and in particular to a combined artificial wetland device for simultaneous denitrification, dephosphorization and defluorination of agricultural irrigation and drainage. Background Art

[0002] Pollutants from industrial, agricultural, and urban sources enter water bodies. Extensive use of regional water and soil resources, coupled with the irrational application of fertilizers and pesticides in irrigation areas, has led to severe water pollution, ecological degradation in irrigation areas, and excessive nitrogen, phosphorus, and fluoride levels in irrigation and drainage water. Excessive nitrogen and phosphorus levels lead to eutrophication, while excessive fluoride intake can cause dental fluorosis and skeletal fluorosis. Animals that consume water and feed with excessive fluoride over a long period of time experience symptoms such as decreased appetite, slowed growth, decreased milk production, limb stiffness, and even death. Excessive fluoride levels can also affect the growth of crops, causing them to become shorter, have poorly developed roots, and yellow leaves. In severe cases, it can even lead to plant death. Therefore, the management of agricultural irrigation and drainage is urgent.

[0003] Constructed wetlands, with their advantages of simple operation, low operating costs, low energy consumption, environmental beautification, and high sustainability, can achieve comprehensive purification of agricultural irrigation and drainage water through adsorption, filtration, sedimentation, ion exchange, plant absorption, and microbial decomposition. In constructed wetland systems, the combined effects of plants, microorganisms, and fillers constitute the key mechanism for nitrogen removal from wastewater. Constructed wetlands not only rely on plant root absorption but also effectively promote nitrogen removal through multiple pathways, including the metabolic activities of rhizosphere and filler microorganisms and the physicochemical properties of the fillers. Microbial denitrification is the primary nitrogen removal pathway. Constructed wetland matrices remove 70-87% of phosphorus from wastewater through processes such as interception, filtration, adsorption, sedimentation, and ion exchange. Aquatic plants can directly absorb and utilize small amounts of organic nutrients and assimilate inorganic phosphorus into ATP, DNA, and RNA. Microorganisms such as phosphate-accumulating bacteria within constructed wetland systems can also absorb and degrade some phosphorus in wastewater. The main methods for treating fluoride in wastewater include chemical precipitation, adsorption, electrodialysis, and ion exchange. Among these methods, adsorption is widely recognized and used due to its low cost, simple process, and excellent treatment results. Constructed wetlands, through the introduction of natural minerals and modified materials, have a good removal effect on fluoride through adsorption and co-precipitation.

[0004] Currently, there are few studies on experimental devices for simultaneous denitrification, phosphorus removal and fluorine removal from agricultural irrigation and drainage, and the sampling control of the device is not precise enough. Therefore, it is necessary to provide a combined artificial wetland experimental device that can achieve simultaneous denitrification, phosphorus removal and fluorine removal from agricultural irrigation and drainage through the combined effects of microbial degradation, plant purification and filler adsorption, as well as a sewage sampling method for stratified detection. Summary of the Invention

[0005] To address the shortcomings of existing technologies and achieve simultaneous denitrification, phosphorus removal, and fluoride removal from agricultural irrigation and drainage, the present invention provides a combined constructed wetland device for simultaneous denitrification, phosphorus removal, and fluoride removal from agricultural irrigation and drainage. This device simulates the combined effects of microbial degradation, plant purification, and filler adsorption in an artificial wetland to purify agricultural irrigation and drainage water. This device simulates the processes of aerobic nitrification and anaerobic denitrification by microorganisms, wetland plant purification and the rhizosphere microbial environment, and phosphorus and fluoride removal by filler and soil in an artificial wetland. The device is divided into several zones, with vertical and laminar flows in different zones connected by perforations. Multiple rows of sampling ports enable sampling at different points during the hydraulic flow, facilitating water quality testing in different zones and locations, resulting in more accurate experimental results.

[0006] In order to solve the above technical problems, the technical solution provided by the present invention is:

[0007] A combined artificial wetland device for agricultural irrigation and drainage with simultaneous denitrification, dephosphorization and defluorination.

[0008] The device sequentially comprises an aerobic nitrification zone 2, an anaerobic denitrification zone 3, a filler adsorption zone 4, and a water outlet zone 5; the bottom of the partition plate between the aerobic nitrification zone 2 and the anaerobic denitrification zone 3 is perforated for hydraulic circulation; the top of the partition plate between the anaerobic denitrification zone 3 and the filler adsorption zone 4 is perforated for hydraulic circulation; the aerobic nitrification zone 2 simulates a microbial nitrification process, the anaerobic denitrification zone 3 simulates a microbial denitrification process, and the filler adsorption zone 4 purifies sewage by adsorption;

[0009] A water inlet overflow trough 1 is provided above one end of the aerobic nitrification zone 2; the water inlet overflow trough 1 is connected to a water supply system, and the water supply system pumps sewage into the water inlet overflow trough 1. After the water inlet overflow trough 1 is full, water falls to achieve water aeration; one end of the water outlet zone 5 is connected to a drainage system;

[0010] The aerobic nitrification zone 2 and the anaerobic nitrification zone 3 are filled with PP suspended ball fillers to extend the hydraulic retention time; the suspended balls are embedded with polyurethane foam 16, which serves as a skeleton for the survival and biofilm formation of microorganisms inoculated with water purification sludge; the suspended balls are also embedded with crushed natural corn cobs 17, which serve as nutrients and carbon sources for the survival of microorganisms. At the same time, the corn cobs 17 serve as a carbon source to provide electron donors for denitrification and denitrification.

[0011] The filler adsorption zone 4 is filled with layered adsorption fillers such as crushed stone, coal gangue, ceramsite and modified natural zeolite for adsorption and removal of phosphorus, nitrogen and fluorine;

[0012] The water flows in the aerobic nitrification zone 2, the anaerobic denitrification zone 3, and the filler adsorption zone 4 in a laminar flow manner;

[0013] The experimental device also includes a sewage sampling system, which includes several rows and columns of sampling ports located in the aerobic nitrification zone 2 and the anaerobic denitrification zone 3, and several sampling ports located in the filler adsorption zone 4, the crushed stone, coal gangue, ceramsite and modified natural zeolite layers, so as to regularly take water samples for testing;

[0014] The device also includes a plant purification system, which includes wetland purification plants 10 located in the aerobic nitrification zone 2 and the anaerobic denitrification zone 3 for removing nitrogen and phosphorus. After the experimental device is filled with water, the plants float on the water surface.

[0015] When the device is in operation, water samples are taken in layers from sampling ports at different heights in the aerobic nitrification zone 2, the anaerobic denitrification zone 3, and the filler adsorption zone 4. The samples are tested and the removal effect of the device on nitrogen, phosphorus, and fluorine wastewater indicators is analyzed.

[0016] Preferably,

[0017] The sampling port is a patch tapping connection between the pagoda head 6 and the silicone hose 15 on one side of the aerobic nitrification zone 2, the anaerobic denitrification zone 3, and the filler adsorption zone 4; the pagoda head 6 is treated with waterproof glue after being connected to the box to prevent water leakage after water is passed through, and the external silicone tube 15 is sealed with a water stop clamp 18 when not sampling;

[0018] The silicone hose 15 connected to the inner side pagoda head 6 of the aerobic nitrification zone 2, the anaerobic denitrification zone 3, and the filler adsorption zone 4 is evenly perforated so that laminar flow can flow out through the silicone hose 15 after filling the aerobic nitrification zone 2, the anaerobic denitrification zone 3, and the filler adsorption zone 4; the silicone hose 15 connected to the outer side pagoda head 6 of the aerobic nitrification zone 2, the anaerobic denitrification zone 3, and the filler adsorption zone 4 is sealed by a water stop clamp 18. When sampling, the water stop clamp 18 is opened, and the syringe and the filter head are connected for sampling.

[0019] Preferably,

[0020] The water inlet overflow trough 1, the aerobic nitrification zone 2, the anaerobic denitrification zone 3, the filler adsorption zone 4, and the water outlet zone 5 are all made of polymethyl methacrylate material with a thickness of 1 cm.

[0021] Preferably,

[0022] The aerobic nitrification zone 2 and the anaerobic nitrification zone 3 are filled with PP suspended ball fillers with a diameter of 80 mm, and the gaps between the suspended balls are uniform; the sewage sampling system is inserted into the gaps to ensure that water samples of corresponding layer heights are obtained during sampling.

[0023] Preferably,

[0024] The crushed stone, coal gangue, ceramsite and modified natural zeolite in the adsorption filler area have a thickness of 7 cm per layer.

[0025] Preferably,

[0026] The water supply system includes a water supply bucket, a peristaltic pump 13 and a silicone hose 15; the water inlet overflow tank 1 is connected to the peristaltic pump 13 and the water supply bucket 14 via the silicone hose 15; water is continuously supplied by replacing the water supply bucket, and the parameters of the peristaltic pump 13 are set according to the flow rate to pump sewage from the water supply bucket into the water inlet overflow tank 1.

[0027] Preferably,

[0028] The drainage system includes a water outlet and a water outlet bucket;

[0029] The water outlet includes a two-way valve 7 and a silicone hose 15 connected by patch tapping at the bottom of the device and the outside of the water outlet area;

[0030] The water outlet at the bottom of the device is used to discharge sewage from the aerobic nitrification zone (2), the anaerobic denitrification zone (3), and the filler adsorption zone (4);

[0031] The water outlet at the upper outer side of the water outlet area controls the liquid level and water discharge in the device, and the water outlet at the lower outer side of the water outlet area 5 is used to drain the water in the water outlet area 5.

[0032] Preferably,

[0033] The purification plant comprises a polyethylene flowerpot with holes punched at the bottom, filled with adsorption fillers and wetland plants; the plant absorbs and removes part of the pollutants in the water body, and the plant root system provides a living environment for bacteria and microorganisms.

[0034] A stratified sampling and detection method for simultaneous denitrification, phosphorus removal, and fluorine removal in agricultural irrigation and drainage, using any of the above-mentioned experimental devices, comprises the following steps:

[0035] S1 configuration required for the experiment simulated sewage, the experimental water required for the water supply bucket into the standby, after calculating the adsorption filler 12 and PP suspended ball filler porosity 11, adjust the appropriate flow rate to simulate sewage water;

[0036] S2. The wastewater is nitrified and denitrified by nitrifying microorganisms in aerobic nitrification zone 2;

[0037] S3. The denitrifying microorganisms in the sewage anaerobic denitrification zone 3 denitrify and remove nitrogen;

[0038] S4. Wastewater is purified by a plant system to remove nitrogen and phosphorus;

[0039] S5. The wastewater is adsorbed by crushed stone, gangue, ceramsite and modified natural zeolite in the filler adsorption zone 4 for phosphorus removal, by ceramsite and modified zeolite in the filler adsorption zone 4 for nitrogen removal, and by modified natural zeolite in the filler adsorption zone 4 for fluorine removal;

[0040] S6. Open the external water stop clamp 18 of the sampling port, take water samples from each sampling port provided in the aerobic nitrification zone 2, the anaerobic denitrification zone 3, and the filler adsorption zone 4, detect the total nitrogen, total phosphorus, ammonia nitrogen, nitrate nitrogen, nitrite nitrogen, and fluoride / fluoride ion content of the water samples, and analyze the removal effect of the device on nitrogen, phosphorus, and fluoride wastewater indicators.

[0041] The beneficial effects of the present invention are:

[0042] First, the invention, "A combined artificial wetland experimental device for simultaneous denitrification, phosphorus removal, and fluorine removal for agricultural irrigation and drainage, and a sewage sampling method for stratified detection," achieves simultaneous denitrification, phosphorus removal, and fluorine removal for agricultural irrigation and drainage through different partitions and functional units (microorganisms, fillers, and plants) of the device. By setting different partitions and controlling the hydraulic retention time, the sewage purification effect is enhanced.

[0043] Second, multiple rows of sampling ports are set up in different zones, which can take out sewage samples in layers for testing, making the test results more accurate;

[0044] Third, according to the actual situation of water purification, a reasonable simulated sewage input flow rate can be set through the peristaltic pump;

[0045] Fourth, the device is overall coherent, has good hydraulic fluidity, and a compact and clear structure. It can drain water from different partitions and has good promotion and utilization value. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0047] Figure 1 Schematic diagram of the structural principle of the present invention

[0048] Figure 2 Schematic diagram of the assembly and filling of the present invention

[0049] Figure 3 Schematic diagram of the operation of the device of the present invention

[0050] Figure 4 Schematic diagram of the sampling port structure

[0051] Figure 5 Schematic diagram of the water outlet structure

[0052] Figure 6 Schematic diagram of plant structure for wetland purification

[0053] Figure 7 Schematic diagram of the PP suspended ball filler structure

[0054] In the figure: 1-water inlet overflow trough, 2-aerobic nitrification zone, 3-anaerobic denitrification zone, 4-filler adsorption zone, 5-water outlet zone, 6-pagoda head, 7-2-way valve, 8-orifice, 9-support leg, 10-wetland purification plant, 11-PP suspended ball filler, 12-adsorption filler, 13-peristaltic pump, 14-polyethylene bucket, 15-silicone hose, 16-polyurethane foam, 17-natural corn cob, 18-water stop clamp. DETAILED DESCRIPTION

[0055] The following describes preferred embodiments of the present invention in conjunction with the accompanying drawings. It should be understood that the following embodiments are provided for illustrative purposes only and are not intended to limit the scope of the present invention. Those skilled in the art may make various modifications and substitutions to the present invention without departing from the purpose and spirit of the present invention.

[0056] like Figure 1 As shown, the present invention is a combined artificial wetland device for agricultural irrigation and drainage with simultaneous denitrification, phosphorus removal and fluorine removal. The device body includes, from left to right, an inlet overflow trough 1, an aerobic nitrification zone 2, an anaerobic denitrification zone 3, a filler adsorption zone 4, an outlet zone 5, a water supply system, a sewage sampling system, a drainage system, and a plant purification system.

[0057] The water inlet overflow trough 1, the aerobic nitrification zone 2, the anaerobic denitrification zone 3, the filler adsorption zone 4, and the water outlet zone 5 are all made of polymethyl methacrylate material with a thickness of 1 cm.

[0058] The water inlet overflow trough 1 is located above the aerobic nitrification zone 2, the aerobic nitrification zone 2 is located on the left side of the anaerobic denitrification zone 3, the bottom partitions of the two partitions are punched for hydraulic circulation, the anaerobic denitrification zone 3 is connected to the filler adsorption zone 4, the top of the partition between the two partitions is punched, and the water outlet zone is located on the right side of the filler adsorption zone.

[0059] The water supply system includes a water supply bucket and a peristaltic pump 13. A water overflow tank 1 is connected to the peristaltic pump 13 and a 50L polyethylene bucket 14 via a silicone hose 15. Sewage is placed in the water supply bucket and continuously fed by changing the bucket. After calculating the flow rate, the peristaltic pump 13 is configured to pump sewage from the water supply bucket into the inlet overflow tank 1. Once the overflow tank 1 is full, a droplet is generated to oxygenate the water. The different zones are connected by perforations 8 to achieve hydraulic circulation. The aerobic nitrification zone 2 and the anaerobic nitrification zone 3 are filled with 80mm diameter PP suspended balls. The suspended balls contain polyurethane foam 16 and crushed natural corn cobs 17. The adsorption zone 4 is filled with layered adsorption filler 12. Water flows in a laminar manner, extending hydraulic retention time and enhancing pollutant removal. The polyurethane foam serves as a scaffold for microbial survival and biofilm formation after inoculation with purified water sludge. The crushed corn cobs provide nutrients and a carbon source for microbial survival. Furthermore, the corn cobs, as a carbon source, provide electrons for the denitrification process. Each suspended ball is evenly filled with square black polyurethane foam and corn cobs. When filling the suspended balls in the aerobic and anaerobic zones, ensure that the gaps are uniform (no large pores are left). When filling the suspended balls, ensure that the silicone hose for stratified sampling on the inside of the box is inserted vertically into the filled pores to ensure that water samples at the corresponding stratification height are taken during sampling.

[0060] The adsorption fillers 12 are crushed stone, coal gangue, ceramsite and modified natural zeolite from bottom to top, with each layer thickness of about 7 cm. The above fillers all adsorb and remove phosphorus, the ceramsite and modified zeolite adsorb and remove nitrogen, and the modified natural zeolite adsorbs and removes fluorine.

[0061] The device is connected to a silicone hose 15 through the water outlet for venting and draining. The sampling ports in different partitions and layers can be used to take water samples for testing regularly. Through the microbial degradation in the aerobic nitrification zone 2 and the anaerobic denitrification zone 3, the purification by the wetland plants 10, and the adsorption of the filler in the filler adsorption zone 4, the simultaneous denitrification, phosphorus removal, and fluorine removal of simulated agricultural irrigation and drainage are achieved.

[0062] The wastewater sampling system includes sampling ports formed by tapping a pagoda head 6 and a silicone hose 15 on one side of the aerobic nitrification zone, anaerobic denitrification zone, and filler adsorption zone. The chambers in the aerobic nitrification zone 2 and anaerobic denitrification zone 3 are approximately 35 cm tall. After the water purification plants are subsequently placed, the chamber walls will be higher to protect the floating baskets and plants and prevent them from falling over. Sampling ports are evenly spaced in three rows and two columns across the two zones. From bottom to top, the heights of the three rows are 9 cm, 18 cm, and 27 cm, respectively. The spacing between the two rows of sampling ports in the aerobic zone is approximately 14.75 cm, and the spacing between the two rows of sampling ports in the anaerobic zone is approximately 11.8 cm. The adsorption area box of the filler adsorption zone 4 is about 33 cm high, and four rows and two columns of sampling ports are set in the middle of the four layers of adsorption filler 12. The four rows of sampling ports are located at 3.5 cm, 10.5 cm, 17.5 cm, and 24.5 cm from the bottom of the box. When filling, ensure that the sampling silicone hose inside the adsorption zone is horizontally inserted into the filler layer, that is, perpendicular to the box wall, to ensure that the water sample at the corresponding height is taken. After the pagoda head 6 is connected to the box, it is treated with waterproof glue to prevent water leakage after water is passed through. The silicone hose 15 connected to the pagoda head 6 on the inside of the box is evenly punched to achieve laminar flow through the silicone hose 15 after the device is filled. The silicone hose 15 connected to the pagoda head 6 on the outside of the box is sealed by a water stop clamp 18. When sampling, open the water stop clamp 18, connect the syringe and the filter head for sampling.

[0063] The drainage system includes a two-way valve 7 and a silicone hose 15 connected by tapping at the bottom of the device and the right side of the outlet area, as well as a polyethylene outlet bucket. The outlet at the bottom of the device allows for the drainage of sewage from different zones. The upper outlet on the right side of the outlet area 5 controls the liquid level and water discharge within the device, while the lower outlet in the outlet area 5 allows for the drainage of water from the outlet area 5. Each of the two-way valves 7 at the different outlets is connected to a silicone hose 15 of corresponding diameter to discharge water into the outlet bucket.

[0064] The plant purification system includes wetland purification plants 10, located in the aerobic nitrification zone 2 and the anaerobic denitrification zone 3. These plants consist of perforated polyethylene pots filled with adsorbent material 12 and wetland plants. When water is supplied to the system, the pots float on the water's surface. The plants absorb and remove nitrogen and phosphorus pollutants from the water, providing nutrients for plant growth. Their roots also provide a habitat for bacteria and microorganisms, and the plants themselves also provide greening properties.

[0065] The bottom of the device is provided with a support leg 9 for support, and the sampling port is used to take water samples in different partitions and at different heights of the box. By analyzing the samples, the removal effect and mechanism of the device on sewage indicators such as nitrogen, phosphorus and fluorine are analyzed.

[0066] The present invention also provides a stratified sampling and detection method for simultaneous denitrification, dephosphorization and defluorination of agricultural irrigation and drainage, comprising the following steps:

[0067] S1 configuration experiment required simulated sewage, the simulated sewage is injected into the polyethylene water supply bucket standby, after calculating the porosity of the adsorption filler 12 and PP suspended ball filler 11, adjust the appropriate flow rate through the peristaltic pump 13 to simulate the sewage water;

[0068] S2. The wastewater is nitrified and denitrified by nitrifying microorganisms in aerobic nitrification zone 2;

[0069] S3. The denitrifying microorganisms in the sewage anaerobic denitrification zone 3 denitrify and remove nitrogen;

[0070] S4. Wastewater is purified by a plant system to remove nitrogen and phosphorus;

[0071] S5. The wastewater is adsorbed by crushed stone, gangue, ceramsite and modified natural zeolite in the filler adsorption zone 4 for phosphorus removal, by ceramsite and modified zeolite in the filler adsorption zone 4 for nitrogen removal, and by modified natural zeolite in the filler adsorption zone 4 for fluorine removal;

[0072] S6. Open the external water stop clamp 18 of the sampling port, take water samples from the sampling ports set in the aerobic nitrification zone 2, the anaerobic denitrification zone 3, and the filler adsorption zone 4, and detect the total nitrogen (TN), total phosphorus (TP), and ammonia nitrogen (NH4 + -N), nitrate nitrogen (NO3 - -N), nitrite nitrogen (NO2 - -N), fluoride / fluoride ion (F - ) content, and analyze the removal effect of the device on nitrogen, phosphorus and fluorine wastewater indicators.

[0073] The contents not described in detail in this specification belong to the prior art known to those skilled in the art.

[0074] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A combined artificial wetland device for agricultural irrigation and drainage with simultaneous denitrification, dephosphorization and defluorination, characterized in that: The device sequentially comprises an aerobic nitrification zone (2), an anaerobic denitrification zone (3), a filler adsorption zone (4), and a water outlet zone (5); the bottom of the partition plate between the aerobic nitrification zone (2) and the anaerobic denitrification zone (3) is perforated for hydraulic circulation; the top of the partition plate between the anaerobic denitrification zone (3) and the filler adsorption zone (4) is perforated for hydraulic circulation; the aerobic nitrification zone (2) simulates a microbial nitrification process, the anaerobic denitrification zone 3 simulates a microbial denitrification process, and the filler adsorption zone (4) purifies sewage by adsorption; A water inlet overflow trough (1) is provided above one end of the aerobic nitrification zone (2); the water inlet overflow trough (1) is connected to a water supply system, and the water supply system pumps sewage into the water inlet overflow trough 1. After the water inlet overflow trough 1 is full, water is poured to achieve water aeration; one end of the water outlet zone (5) is connected to a drainage system; The aerobic nitrification zone (2) and the anaerobic nitrification zone (3) are filled with PP suspended ball fillers to extend the hydraulic retention time; the suspended balls are internally filled with polyurethane foam (16) to serve as a skeleton for the survival and biofilm formation of microorganisms inoculated with water purification sludge; the suspended balls are also internally filled with crushed natural corn cobs (17) to serve as nutrients and carbon sources for the survival of microorganisms, and the corn cobs (17) serve as a carbon source to provide electron donors for denitrification and denitrification; The filler adsorption zone (4) is filled with layered adsorption fillers such as crushed stone, coal gangue, ceramsite and modified natural zeolite for adsorption and removal of phosphorus, nitrogen and fluorine; The water flows in the aerobic nitrification zone (2), the anaerobic denitrification zone (3), and the filler adsorption zone (4) in a laminar flow manner; The experimental device also includes a sewage sampling system, which includes a plurality of rows and columns of sampling ports located in the aerobic nitrification zone (2) and the anaerobic denitrification zone (3) and a plurality of sampling ports located in the filler adsorption zone (4) for each layer of crushed stone, coal gangue, ceramsite and modified natural zeolite, so as to regularly take water samples for testing; The device also includes a plant purification system, which includes wetland purification plants (10) located in the aerobic nitrification zone (2) and the anaerobic denitrification zone (3) for removing nitrogen and phosphorus; after water is passed through the experimental device, the plants float on the water surface; When the device is in operation, water samples are taken in layers from sampling ports at different heights in the aerobic nitrification zone (2), the anaerobic denitrification zone (3), and the filler adsorption zone (4), and the samples are tested to analyze the removal effect of the device on nitrogen, phosphorus, and fluorine wastewater indicators.

2. The combined artificial wetland device for simultaneous denitrification, dephosphorization and defluorination of agricultural irrigation and drainage according to claim 1 is characterized in that: The sampling port is connected to the aerobic nitrification zone (2), the anaerobic denitrification zone (3), and the filler adsorption zone (4) by tapping the patch on one side thereof with a pagoda head (6) and a silicone hose (15); the pagoda head (6) is treated with waterproof glue after being connected to the box body to prevent water leakage after water is passed through; when not sampling, the external silicone hose (15) is sealed with a water stop clamp (18); The silicone hose (15) connected to the inner side pagoda head (6) of the aerobic nitrification zone (2), the anaerobic denitrification zone (3), and the filler adsorption zone (4) is evenly perforated so that the laminar flow of the aerobic nitrification zone (2), the anaerobic denitrification zone (3), and the filler adsorption zone (4) flows out through the silicone hose (15) after filling; the silicone hose (15) connected to the outer side pagoda head (6) of the aerobic nitrification zone (2), the anaerobic denitrification zone (3), and the filler adsorption zone (4) is sealed by a water stop clamp (18). When sampling, the water stop clamp (18) is opened, and a syringe and a filter head are connected to perform sampling.

3. The combined artificial wetland device for simultaneous denitrification, dephosphorization and defluorination of agricultural irrigation and drainage according to claim 1 is characterized in that: The water inlet overflow trough (1), aerobic nitrification zone (2), anaerobic denitrification zone (3), filler adsorption zone (4), and water outlet zone (5) are all made of polymethyl methacrylate material with a thickness of 1 cm.

4. The combined artificial wetland device for simultaneous denitrification, dephosphorization and defluorination of agricultural irrigation and drainage according to claim 1 is characterized in that: The aerobic nitrification zone (2) and the anaerobic nitrification zone (3) are filled with PP suspended ball fillers with a diameter of 80 mm, and the gaps between the suspended balls are uniform; the sewage sampling system is inserted into the gaps to ensure that water samples of corresponding layer heights are obtained during sampling.

5. The combined artificial wetland device for simultaneous denitrification, dephosphorization and defluorination of agricultural irrigation and drainage according to claim 1 is characterized in that: The crushed stone, coal gangue, ceramsite and modified natural zeolite in the adsorption filler area have a thickness of 7 cm per layer.

6. The combined artificial wetland device for simultaneous denitrification, dephosphorization and defluorination of agricultural irrigation and drainage according to claim 1 is characterized in that: The water supply system comprises a water supply bucket, a peristaltic pump (13) and a silicone hose (15); the water inlet overflow trough (1) is connected to the peristaltic pump (13) and the water supply bucket (14) via the silicone hose (15); water is continuously supplied by replacing the water supply bucket, and the parameters of the peristaltic pump (13) are set according to the flow rate to pump sewage from the water supply bucket into the water inlet overflow trough (1).

7. The combined artificial wetland device for simultaneous denitrification, dephosphorization and defluorination of agricultural irrigation and drainage according to claim 1 is characterized in that: The drainage system includes a water outlet and a water outlet bucket; The water outlet comprises a two-way valve (7) and a silicone hose (15) connected by patch tapping at the bottom of the device and the outside of the water outlet area respectively; The water outlet at the bottom of the device is used to discharge sewage from the aerobic nitrification zone (2), the anaerobic denitrification zone (3), and the filler adsorption zone (4); The water outlet at the upper outer portion of the water outlet area controls the liquid level and water body in the device to be discharged, and the water outlet at the lower outer portion of the water outlet area (5) is used to empty the water body in the water outlet area (5).

8. The combined artificial wetland device for simultaneous denitrification, dephosphorization and defluorination of agricultural irrigation and drainage according to claim 1 is characterized in that: The purification plant comprises a polyethylene flowerpot with holes punched at the bottom, filled with adsorption fillers and wetland plants; the plant absorbs and removes part of the pollutants in the water body, and the plant root system provides a living environment for bacteria and microorganisms.

9. A stratified sampling and detection method for simultaneous denitrification, phosphorus removal, and fluorine removal in agricultural irrigation and drainage, using the experimental device according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1. Configure the simulated sewage required for the experiment, inject the water required for the experiment into the water supply bucket for standby, calculate the porosity of the adsorption filler and PP suspended ball filler (11), and adjust the appropriate flow rate to simulate the sewage water; S2. The sewage is nitrified and denitrified by nitrifying microorganisms in the aerobic nitrification zone (2); S3. The denitrifying microorganisms in the anaerobic denitrification zone (3) of the sewage perform denitrification and nitrogen removal; S4. Wastewater is purified by a plant system to remove nitrogen and phosphorus; S5. The wastewater is adsorbed by crushed stone, gangue, ceramsite and modified natural zeolite in the filler adsorption zone (4) for phosphorus removal, by ceramsite and modified zeolite in the filler adsorption zone (4) for nitrogen removal, and by modified natural zeolite in the filler adsorption zone (4) for fluorine removal; S6. Open the external water stop clamp (18) of the sampling port, take water samples from each sampling port set in the aerobic nitrification zone (2), the anaerobic denitrification zone (3), and the filler adsorption zone (4), detect the total nitrogen, total phosphorus, ammonia nitrogen, nitrate nitrogen, nitrite nitrogen, and fluoride / fluoride ion content of the water samples, and analyze the removal effect of the device on nitrogen, phosphorus, and fluoride wastewater indicators.

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