An agricultural non-point source pulse type high-load phosphorus pollution end interception system and method

Abstract

The present application is a kind of agricultural non-point source pulse high-load phosphorus pollution end interception system and method, the system comprises: water flow interception channel interception bottom plate, and a pair of water flow interception channel interception side plates connected to the two side edges of the water flow interception channel interception bottom plate and inclined outward, to form a trapezoidal cross-section water flow interception channel structure;Flow guide interception plate, a plurality of flow guide interception plates are connected on the inner side of the water flow interception channel interception side plate at a distance and an angle, to form a vortex in the space between the flow guide interception plates, intercept and precipitate the particulate phosphorus in agricultural non-point source pollution;Nutrient adsorption recovery bag filled with adsorption material, a plurality of nutrient adsorption recovery bags are attached to the space between the flow guide interception plates in a dot matrix manner, to adsorb water-soluble phosphorus in agricultural non-point source pollution. The system of the present application can be deployed and intercepted quickly, can be prefabricated, can effectively control pollutants, can also be recycled, and is more ecological and environmentally friendly.

Description

Technical Field

[0001] This invention relates to the field of agricultural non-point source pollution interception technology, and in particular to end-of-pipe interception of pulsed high-load phosphorus pollution from agricultural non-point sources. Background Technology

[0002] Agricultural non-point source pollution: Pollutants generated during agricultural production and not properly treated cause pollution to water bodies, soil, air, and agricultural products. This pollution is characterized by its uncertain location, pathways, and quantities, high randomness, wide range of occurrence, and difficulty in prevention and control. Agricultural non-point source pollution mainly originates from waste generated during rural crop production, including pesticides and fertilizers lost due to improper use, agricultural film residues in farmland, improperly disposed livestock and poultry manure, foul gases, and water pollutants from unscientific aquaculture.

[0003] Agricultural non-point source pulse phosphorus pollution: The main characteristic of agricultural non-point source phosphorus pulse pollution is the dramatic seasonal fluctuation of pollution, particularly during critical periods of agricultural production, such as the rice planting season in June and July, or the crab pond wastewater discharge season in October. Large amounts of phosphorus and other nutrients enter natural water bodies in a pulse-like manner through farmland or aquaculture wastewater, causing a sharp increase in short-term pollution intensity and a rapid deterioration of natural water quality indicators (e.g., Figure 1 It is characterized by short response time, high difficulty, high load, and high environmental pressure.

[0004] Characteristics of agricultural non-point source phosphorus pollution: Studies have shown that 70% of phosphorus emissions from agricultural non-point source pollution are released into water bodies as soil particles, while the remaining 30% enters water bodies as dissolved phosphates. Therefore, controlling phosphorus in agricultural non-point source pollution requires intercepting both particulate and dissolved phosphorus.

[0005] In response to the problem that the above-mentioned agricultural non-point source pulse pollution is intense and that existing ecological interception devices are prone to failure due to excessive load, this invention provides an end-of-pipe interception system and method for agricultural non-point source pulse high-load phosphorus pollution, which has the advantages of rapid interception, effective control of pollutants, recyclability, and environmental protection. Summary of the Invention

[0006] The purpose of this invention is to overcome the problems existing in the prior art and provide an end-of-pipe interception system and method for agricultural non-point source pulse-type high-load phosphorus pollution.

[0007] To achieve the above-mentioned technical objectives and effects, the present invention is implemented through the following technical solution: An agricultural non-point source pulsed high-load phosphorus pollution end-of-pipe interception system, the system comprising: A water flow interception channel bottom plate and a pair of water flow interception channel side plates that connect the two sides of the water flow interception channel bottom plate and are inclined outwards, to form a water flow interception channel structure with a trapezoidal cross section; A flow-guiding and intercepting plate consists of several flow-guiding and intercepting plates that are spaced apart and can be rotated at an angle and connected to the inner side of the side plate of the water flow interception channel. This creates a vortex in the space between the flow-guiding and intercepting plates to intercept and precipitate particulate phosphorus in agricultural non-point source pollution. Nutrient adsorption and recovery packs containing adsorption material are attached in a dot matrix pattern in the space between each flow-guiding interception plate to adsorb water-soluble phosphorus from agricultural non-point source pollution.

[0008] Furthermore, the flow-guiding interceptor plate is an elastic element, with one side of the flow-guiding interceptor plate directly connected to the inner side of the water flow interception channel side plate. The flow-guiding interceptor plate deforms to different degrees with the water flow velocity, thereby adaptively adjusting its angle with the water flow interception channel side plate according to the water flow rate.

[0009] Furthermore, one side of the flow-guiding interceptor plate is hinged to the inner side of the water flow interception channel side plate, so as to constrain the rotation range of the flow-guiding interceptor plate with the hinge structure to adapt to different water flow rates.

[0010] Furthermore, the nutrient adsorption and recovery package is a strip-shaped bag made of biodegradable non-woven plastic fabric, and the strip-shaped bag contains biochar-supported nano-zero-valent iron material as an adsorption material.

[0011] Furthermore, several of the nutrient adsorption and recovery packs are connected in series and vertically positioned in the space between each flow-guiding and intercepting plate. The bottom end of each nutrient adsorption and recovery pack is fixed to the bottom plate of the water flow intercepting channel by an elastic element, so that the series of nutrient adsorption and recovery packs swing at a certain angle with the eddy current.

[0012] Furthermore, the top of the nutrient adsorption and recovery pack is connected to a corresponding fixing structure set above the bottom plate of the water flow interception channel via an elastic element, in order to limit the swing range of the adsorption and recovery fertilizer pack.

[0013] Furthermore, a pair of cross-sectional runoff ports are provided on one end face of the water flow interception channel structure for water inlet and outlet, respectively, and a drain / inlet is provided on the other end face of the water flow interception channel structure for drainage or backwashing water inlet.

[0014] Furthermore, the cross-sectional runoff port is connected to an L-shaped pipe, and the water level is adjusted by the height of the vertical L-side of the L-shaped pipe.

[0015] A method for end-of-pipe interception of high-load phosphorus pollution from agricultural non-point source pulses, comprising the following steps: Step 1) Install the bottom plate and side plate of the water flow interception channel side by side on the side of the existing ditch to form a trapezoidal cross-section water flow interception channel structure; Step 2) Connect the water flow interception channel structure to the traditional ditch via an L-shaped pipe at the cross-sectional runoff interface; Step 3) Connect the external water flow interception channel to the traditional ditch through a three-way valve at the outlet / inlet of the water flow interception channel structure; Step 4) During the period of high-load pulse phosphorus pollution from agricultural non-point sources, biochar-loaded nano-zero-valent iron material is pre-filled into strip-shaped bags made of biodegradable plastic non-woven fabric. Step 5) Based on the water level and flow velocity, L-shaped pipes with different vertical L-shaped sides are selected to adjust the water level. At the same time, the water outlet of the traditional ditch is cut off. After the water flows into the water flow interception channel structure under atmospheric pressure, the angle between the flow guide interception plate and the side plate of the water flow interception channel is adjusted adaptively or actively according to the flow velocity. By utilizing the viscosity and eddy effect of water, the water flow velocity slows down at the flow guide interception plate, and particulate phosphorus is intercepted and precipitated step by step. Meanwhile, water-soluble phosphorus is effectively fixed under the strong adsorption of biochar-supported nano-zero-valent iron materials. Step 6) After the pulse-type high-load phosphorus pollution interception of agricultural non-point source pollution is completed, switch the three-way valve at the inlet / outlet of the water flow interception channel structure so that the water in the conventional ditch can directly enter the water flow interception channel structure from the inlet / outlet for backwashing. The particulate phosphorus intercepted during the interception process is backwashed to the cross-sectional runoff interface. At the same time, reduce the height of the vertical L side of the L-shaped pipe, change the L-shaped pipe at the cross-sectional runoff interface to a low-position pipe, and put a nutrient collection bag made of biodegradable non-woven fabric on the horizontal L side of the L-shaped pipe to collect particulate phosphorus. Step 7) Return the nutrient collection bag and the collected granular phosphorus directly to the field, and use the adsorbed and recovered fertilizer bag and the collected water-soluble phosphorus as the basic raw materials for developing carbon-based phosphorus-rich and iron-rich compost or organic fertilizer.

[0016] In step 4): Biodegradable plastic nonwoven fabrics are preferably made of PLA and PBAT materials, and are produced using a pulp airflow process, ensuring that the fiber diameter is 20±5μm and the unit area weight is 120±10g / m². 2 And use a 2mm roller needle to punch holes, so that the hole density is 4 holes per square centimeter, forming a biodegradable plastic non-woven fabric web; The preferred materials for supporting zero-valent iron nanoparticles in biochar are wheat, rice, and corn straw. The straw is crushed to 5-8 cm and then pyrolyzed at 450°C to obtain biochar. Zero-valent iron nanoparticles are then prepared using a liquid-phase reduction method, resulting in an average particle size of 50 nm, a purity of 99.9%, and a specific surface area of ​​20 m² / g. 2 / g, bulk density 2.3 g / cm³ 3During the loading process, nitrogen gas is used for protection, and magnetic separation is used for separation. The separated biochar-loaded nano-zero-valent iron material is then washed with deoxygenated water and dried, packed into plastic sealed bags, and filled with nitrogen gas for protection for later use, ensuring that the amount of nano-zero-valent iron loaded in each 1 kg of biochar is not less than 35.0 g.

[0017] The beneficial effects of this invention are: The system of this invention can be deployed and intercepted quickly, can be prefabricated, can effectively control pollutants, and can be recycled. It only needs to replace the biochar-supported nano-zero-valent iron material, making it more ecological and environmentally friendly. Attached Figure Description

[0018] Figure 1 This is a diagram illustrating the characteristics of pulsed high-load phosphorus pollution. Figure 2 This is a three-dimensional structural diagram of the end-point interception system of the present invention; Figure 3 This is a structural diagram of the adsorption and recovery fertilizer pack and elastic element of the present invention; Figure 4 This is a structural diagram of the L-shaped tube of the present invention; Figure 5 This is a schematic diagram of the deployment of the end-point interception system of the present invention; Figure 6 The diagram shows the working states of the end-of-line interception system of the present invention: (a) is the non-intercepting state, (b) is the intercepting state, and (c) is the backwashing state.

[0019] The following are the labels in the diagram: 1. Water flow interception channel bottom plate, 2. Water flow interception channel side plate, 3. Flow guide interception plate, 4. Adsorption and recovery fertilizer bag, 5. L-shaped pipe, 6. Elastic component, 7. Cross-sectional runoff interface, 8. Drain / inlet. Detailed Implementation

[0020] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0021] like Figure 2 As shown, an agricultural non-point source pulsed high-load phosphorus pollution end-of-pipe interception system includes: The water flow interception channel base plate 1 and a pair of water flow interception channel side plates 2 that connect the two sides of the water flow interception channel base plate 1 and are inclined outwards form a water flow interception channel structure with a trapezoidal cross section. The water flow interception channel structure is made of PPC material with a thickness of preferably 2 mm. The components are assembled by hot welding. The overall length of the water flow interception channel structure is not less than 10 m and generally not more than 20 m, which can be estimated according to the intensity of ground source pollution at the implementation site. The upper edge of the trapezoidal cross section is 2 m wide, the lower edge is 1 m wide, the side inclination angle is 30 degrees, and the height is 1 m. A number of flow-guiding and intercepting plates 3 are connected at a distance and can be rotated to the inner side of the side plate 2 of the water flow interception channel to form a vortex in the space between each flow-guiding and intercepting plate 3, thereby intercepting and settling particulate phosphorus in agricultural non-point source pollution. The adsorption and recycling fertilizer pack 4, which contains adsorption material, is attached in a dot matrix pattern in the space between each flow-guiding interception plate 3. There are about 12 sets of adsorption and recycling fertilizer packs 4 per meter, which are used to adsorb water-soluble phosphorus in agricultural non-point source pollution.

[0022] The flow guide plate 3 is an elastic element. One side of the flow guide plate 3 is directly connected to the inner side of the water flow interception channel side plate 2. The flow guide plate 3 deforms to different degrees with the water flow speed, thereby adaptively adjusting the angle between it and the water flow interception channel side plate 2 according to the water flow rate.

[0023] One side of the flow-diverting interceptor plate 3 is hinged to the inner side of the water flow interception channel side plate 2. The hinge structure constrains the rotation range of the flow-diverting interceptor plate 3 to adapt to different water flow rates. The flow-diverting interceptor plate 3 can also be made of PPC material, with a preferred thickness of 2mm, a preferred height of 0.8m, and a preferred upper edge length of 0.5m. The rotation range of the flow-diverting interceptor plate 3 constrained by the hinge structure is -30 to 15 degrees. The hinge structure can be a common hinge. Corresponding limiting ribs are set at the intersection of the flow-diverting interceptor plate 3 and the water flow interception channel side plate 2 to make its rotation range -30 to 15 degrees. The specific angle can be adjusted according to the water flow rate. For example, when the water flow rate is large, the flow-diverting interceptor plate 3 and the water flow interception channel side plate 2 are no longer perpendicular and need to be rotated at a larger angle to achieve the effect of widening the water flow interception channel structure and preventing water from overflowing or spilling from the traditional ditch.

[0024] The adsorption and recycling fertilizer pack 4 is a strip bag made of biodegradable plastic non-woven fabric. The length and width of the strip bag are preferably 0.2 m × 0.05 m. Biochar-supported nano-zero-valent iron material is placed inside the strip bag as an adsorption material.

[0025] like Figure 3 As shown, several adsorption and recovery fertilizer packs 4 are connected in series and vertically located in the space between each flow-guiding and intercepting plate 3. The bottom end of the adsorption and recovery fertilizer pack 4 is fixed to the bottom plate 1 of the water flow intercepting channel by an elastic member 6, so that the series of adsorption and recovery fertilizer packs 4 swing at a certain angle with the eddy current.

[0026] The top of the adsorption and recovery fertilizer pack 4 is connected to a corresponding fixed structure above the bottom plate 1 of the water flow interception channel via an elastic element 6 to limit the swing range of the adsorption and recovery fertilizer pack 4. The fixed structure can be an elastic rope that stretches across the top of the water flow interception channel structure for the elastic element 6 at the top of the adsorption and recovery fertilizer pack 4 to hook onto. The elastic element 6 can be a spring hook with hooks at both ends. The hook of the spring hook at the bottom of the adsorption and recovery fertilizer pack 4 is hooked onto a corresponding hookable structure on the bottom plate 1 of the water flow interception channel, such as a hook nose structure. The hook of the spring hook at the top of the adsorption and recovery fertilizer pack 4 is hooked onto the rope.

[0027] A pair of cross-sectional runoff inlets 7 are provided on one end face of the water flow interception channel structure. Each cross-sectional runoff inlet 7 is a threaded circular opening with a diameter of 50cm, located approximately 1 / 3 of the height from the bottom plate 1 of the water flow interception channel within the trapezoidal cross-section. These inlets and outlets are used for water inlet and outlet, respectively. The other end face of the water flow interception channel structure is provided with a drain / inlet 8 for drainage or backwashing water inlet. Each drain / inlet 8 is a circular opening with a diameter of 50cm. Figure 5 As shown, the first path of the three-way valve is connected to the external water flow interception channel, and the second path of the three-way valve is connected to the existing traditional ditch. During the peak period of non-point source pollution discharge or after the end of planting and breeding, water is introduced into the discharge / inlet 8 through the three-way valve to backwash the water flow interception channel structure. At the same time, the L-shaped pipe 5 is set at a height of 5cm, and a nutrient collection bag made of biodegradable non-woven fabric is fitted on the cross-sectional runoff interface 7. The nutrient collection bag collects particulate phosphorus. The length and diameter of the nutrient collection bag are 0.5m × 0.5m, and the aperture is 2mm. The intercepted particulate phosphorus is backwashed into the nutrient collection bag by the water flow. The nutrient collection bag can remain basically undegraded in water for 3 months. After 3 months from the end of the pulse high-load phosphorus pollution, the nutrient collection bag and particulate phosphorus are plowed into the soil to a depth of 20cm.

[0028] The cross-sectional runoff inlet 7 connects to an L-shaped pipe 5, which is a PVC pipe. The water level is adjusted by the height of the vertical L-side of the L-shaped pipe 5. Figure 4 As shown, the vertical L-shaped pipe 5 has vertical pipe heights of 5cm, 25cm, 50cm and 1m corresponding to its vertical side. It uses the principle of communicating vessels to allow water to enter and maintain the water level. It can be selected according to four situations: backwash water level, low water level, high water level, and no drainage. When not in use, it can be connected to a 1m high vertical pipe. When backwashing and draining, it can be connected to vertical pipes of 5cm, 25cm and 50cm high respectively.

[0029] A method for end-of-pipe interception of high-load phosphorus pollution from agricultural non-point source pulses, comprising the following steps: Step 1) Install the bottom plate 1 and the side plate 2 of the water flow interception channel side by side on the side of the existing ditch to form a trapezoidal cross-section water flow interception channel structure; Step 2) Connect the water flow interception channel structure to the traditional ditch via an L-shaped pipe 5 at the runoff interface 7 of the cross-section; Step 3) Connect the external water flow interception channel to the traditional ditch through a three-way valve at the outlet / inlet 8 of the water flow interception channel structure; Step 4) During the period of high-load pulse phosphorus pollution from agricultural non-point sources, biochar-loaded nano-zero-valent iron material is pre-filled into strip-shaped bags made of biodegradable plastic non-woven fabric. Step 5) Based on the water level and flow velocity, select L-shaped pipes 5 with different vertical L-side heights to adjust the water level, such as... Figure 6 As shown in (b), the three-way valve is switched to cut off the water outlet of the traditional ditch. After the water flows into the water interception channel structure under atmospheric pressure, the angle between the flow interception plate 3 and the side plate 2 of the water interception channel is adaptively or actively adjusted according to the flow velocity. By utilizing the viscosity and eddy effect of water, the flow velocity of the water slows down at the flow interception plate 3. Particulate phosphorus is intercepted and precipitated step by step, while water-soluble phosphorus is effectively fixed under the strong adsorption of the biochar-supported nano zero-valent iron material. The biochar-supported nano zero-valent iron material should be replaced every 72 hours to achieve better results. Step 6) After the pulsed high-load phosphorus pollution interception of agricultural non-point source pollution is completed, such as Figure 6 As shown in (c), the three-way valve at the outlet / inlet 8 of the water flow interception channel structure is switched so that the water from the regular ditch can directly enter the water flow interception channel structure for backwashing. The particulate phosphorus intercepted during the interception process is backwashed to the cross-sectional runoff interface 7. At the same time, the vertical L-side height of the L-shaped pipe 5 is reduced, and the L-shaped pipe 5 at the cross-sectional runoff interface 7 is changed to a low-position pipe. A nutrient collection bag made of biodegradable non-woven fabric is sleeved on the horizontal L-side of the L-shaped pipe 5 to collect particulate phosphorus. Step 7) Return the nutrient collection bag and the collected granular phosphorus directly to the field, and use the adsorbed and recovered fertilizer bag 4 and the collected water-soluble phosphorus as the basic raw materials for developing carbon-based phosphorus-rich and iron-rich compost or organic fertilizer.

[0030] In step 4): Biodegradable plastic nonwoven fabrics are preferably made of PLA and PBAT materials, and are produced using a pulp airflow process, ensuring that the fiber diameter is 20±5μm and the unit area weight is 120±10g / m². 2 And use a 2mm roller needle to punch holes, so that the hole density is 4 holes per square centimeter, forming a biodegradable plastic non-woven fabric web; The preferred materials for supporting zero-valent iron nanoparticles in biochar are wheat, rice, and corn straw. The straw is crushed to 5-8 cm and then pyrolyzed at 450°C to obtain biochar. Zero-valent iron nanoparticles are then prepared using a liquid-phase reduction method, resulting in an average particle size of 50 nm, a purity of 99.9%, and a specific surface area of ​​20 m² / g. 2 / g, bulk density 2.3 g / cm³ 3 During the loading process, nitrogen gas is used for protection, and magnetic separation is used for separation. The separated biochar-loaded nano-zero-valent iron material is then washed with deoxygenated water and dried, packed into plastic sealed bags, and filled with nitrogen gas for protection for later use, ensuring that the amount of nano-zero-valent iron loaded in each 1 kg of biochar is not less than 35.0 g. Example

[0031] (1) This invention controls phosphorus pollution in paddy field ditches: The basic ratio of paddy fields to end-of-pipe interception is 100 meters of water flow interception channel structure per hectare of paddy field; During the peak period of phosphorus emission in paddy fields, usually in July and August, biochar-supported nano-zero-valent iron material is prepared one week in advance before interception. It is then packed into adsorption and recycling fertilizer bags made of biodegradable plastic non-woven fabric 2-3 days before the planned interception, and fixed at a ratio of 60 bags per meter of ditch. During the paddy field drainage period, the vertical pipe of the L-shaped pipe 5 at the cross-section runoff interface 7 is first raised to 25cm. When the water volume is large, it can be raised to 50cm. During the peak period of phosphorus emission, the biochar-supported nano-zero-valent iron material is replaced every 1-2 weeks. If under emergency high intensity, it can be replaced every 72 hours. The entire phosphorus high-load end interception time is generally 90 days.

[0032] The effects of this invention are compared with those of conventional ditches, and the results are shown in the table below: Purification device Total phosphorus content in influent (mg / kg) Influent particulate phosphorus content (mg / kg) Water-soluble phosphorus content in influent (mg / kg) Total phosphorus content in effluent (mg / kg) Particulate phosphorus content in effluent (mg / kg) Water-soluble phosphorus content in effluent (mg / kg) Total phosphorus interception rate (%) Traditional ditches 1.7 1.2 0.5 1.54 1.12 0.42 10% End-of-line interception system 1.7 1.2 0.5 0.265 0.22 0.045 84% After interception is completed, the entire end-of-pipe interception system is backflushed through a three-way valve, and the collected particulate phosphorus and biochar material are either recycled or directly returned to the field.

[0033] The results show that the total phosphorus interception rate using this end-of-pipe interception system is 84%, which is significantly higher than the conventional 10%.

[0034] (2) This invention controls phosphorus pollution in crab farming ponds; The basic ratio of crab ponds to end-of-pipe interception systems is 0.5 hectares per 100-meter end-of-pipe interception system; During the peak phosphorus discharge period in crab ponds, which is usually in May and August, the main sources of phosphorus discharge are organic fertilizers and potassium dihydrogen phosphate applied to stimulate the growth of aquatic plants in the crab ponds. At the end of the aquaculture season, which is usually in November, biochar-loaded nano-zero-valent iron materials are prepared one week in advance and then packed into biodegradable plastic non-woven fabric adsorption and recycling fertilizer bags 4 2-3 days before the planned interception. The bags are fixed at a ratio of 60 bags per meter of ditch.

[0035] During the water exchange or drainage period in the crab pond, first raise the vertical pipe of the L-shaped pipe 5 at the cross-sectional runoff interface 7 to 25cm. When the water volume is large, it can be raised to 50cm. During the peak period of phosphorus discharge, replace the biochar-loaded nano-zero-valent iron material every 1-2 weeks. The terminal interception time of high phosphorus load in crab ponds is generally short, usually about 7 days. The particulate phosphorus is lower than that in farmland tailwater, but the water volume of aquaculture tailwater is much higher than that in farmland. Based on actual operating experience, in addition to regularly replacing the biochar-loaded nano-zero-valent iron material, this system can also be backwashed after the crab farming is completed.

[0036] This embodiment compares traditional aquaculture drainage ditches with this end-of-pipe interception system, and the results are shown in the table below: Purification device Total phosphorus content in influent (mg / kg) Influent particulate phosphorus content (mg / kg) Water-soluble phosphorus content in influent (mg / kg) Total phosphorus content in effluent (mg / kg) Particulate phosphorus content in effluent (mg / kg) Water-soluble phosphorus content in effluent (mg / kg) Total phosphorus interception rate (%) Traditional ditches 0.64 0.21 0.43 0.26 0.11 0.15 59% End-of-line interception system 0.64 0.21 0.43 0.07 0.05 0.02 89% The results show that the total phosphorus interception rate of this end-of-pipe interception system is 89%, which is significantly higher than the conventional 59%, achieving a significant interception effect.

[0037] (3) This invention intercepts phosphorus pollution in biogas slurry; This implementation case is used to intercept phosphorus non-point source pollution in farmland using biogas slurry. Biogas slurry is a by-product of livestock and poultry farming, rich in phosphorus nutrients, and is often used as organic fertilizer to provide nutrients for crops. At the same time, improper irrigation during the application of biogas slurry can easily cause pulse-like high-load pollution of agricultural non-point source pollution. Based on the site topography and discharge characteristics, this invention is selected for application in farmland drainage ditches where biogas slurry is applied: Taking open-field vegetable fields as an example, the basic ratio of vegetable fields to end-of-pipe interception is 100 meters of end-of-pipe interception system per hectare of paddy field. During the application of biogas slurry in the vegetable field, biochar-supported nano-zero-valent iron material is prepared one week in advance or biochar-supported nano-zero-valent iron material stored in nitrogen is used. Two to three days before the interception is prepared, the biochar-supported nano-zero-valent iron material is put into the adsorption and recycling fertilizer bag 4 made of biodegradable plastic non-woven fabric and fixed at a ratio of 60 bags per meter of ditch. If biogas slurry is found to be leaking into the ditch during the application of biogas slurry, first raise the vertical pipe of the L-shaped pipe 5 at the cross-section runoff interface 7 to 25 cm. When the water volume is large, it can be raised to 50 cm. Under normal circumstances, during the peak period of phosphorus emission, the biochar-supported nano zero-valent iron material is replaced every 3 days. The end interception time of high phosphorus load during the biogas slurry application process is generally short, about 1-3 days. This embodiment compares conventional ditches with this end-point interception system, and the results are shown in the table below: The results showed that, despite the high phosphorus concentration in the biogas slurry, the total interception rate after treatment by the end-of-pipe interception system could still reach 65.9%, which was significantly higher than that of traditional ditches.

[0038] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A terminal interception system for high-load phosphorus pollution from agricultural non-point source pulses, characterized in that, The system includes: A water flow interception channel bottom plate (1) and a pair of water flow interception channel side plates (2) that connect the two sides of the water flow interception channel bottom plate (1) and are inclined outwards, to form a water flow interception channel structure with a trapezoidal cross section; A flow-guiding interception plate (3) is connected to the inner side of the side plate (2) of the water flow interception channel at a distance and can be rotated to form a vortex in the space between each flow-guiding interception plate (3) to intercept and precipitate particulate phosphorus in agricultural non-point source pollution. Nutrient adsorption and recovery packs (4) containing adsorption materials are attached in a dot matrix manner in the space between each flow-guiding interception plate (3) to adsorb water-soluble phosphorus in agricultural non-point source pollution. The flow-guiding interceptor plate (3) is an elastic element. One side of the flow-guiding interceptor plate (3) is directly connected to the inner side of the water flow interception channel side plate (2). The flow-guiding interceptor plate (3) deforms to different degrees with the water flow speed, thereby adjusting the angle between it and the water flow interception channel side plate (2) according to the water flow rate. One side of the flow-guiding interceptor plate (3) is hinged to the inner side of the water flow interception channel side plate (2) to constrain the rotation range of the flow-guiding interceptor plate (3) with the hinge structure to adapt to different water flow rates; The nutrient adsorption and recovery package (4) is a strip bag made of biodegradable plastic non-woven fabric, and biochar-supported nano-zero-valent iron material is placed inside the strip bag as an adsorption material. Several nutrient adsorption and recovery packs (4) are connected in series and vertically located in the space between each flow interception plate (3). The bottom end of each nutrient adsorption and recovery pack (4) is fixed to the bottom plate (1) of the water flow interception channel by an elastic element (6), so that the series of nutrient adsorption and recovery packs (4) swing at a certain angle with the eddy current.

2. The agricultural non-point source pulsed high-load phosphorus pollution end-of-pipe interception system according to claim 1, characterized in that, The top of the nutrient adsorption and recovery pack (4) is connected to the corresponding fixing structure set above the bottom plate (1) of the water flow interception channel via an elastic element (6) to limit the swing range of the nutrient adsorption and recovery pack (4).

3. The agricultural non-point source pulse-type high-load phosphorus pollution end-of-pipe interception system according to claim 1, characterized in that, A pair of cross-sectional runoff ports (7) are provided on one end face of the water flow interception channel structure for water inlet and outlet respectively, and a drain / inlet port (8) is provided on the other end face of the water flow interception channel structure for drainage or backwashing water inlet.

4. The agricultural non-point source pulse-type high-load phosphorus pollution end-of-pipe interception system according to claim 3, characterized in that, The cross-sectional runoff port (7) is connected to the L-shaped pipe (5), and the water level is adjusted by the height of the vertical L side of the L-shaped pipe (5).

5. A method for intercepting high-load phosphorus pollution from agricultural non-point source pulsed terminal interception systems according to any one of claims 1-4, characterized in that, The method includes the following steps: Step 1) Install the bottom plate (1) and side plate (2) of the water flow interception channel side by side on the side of the existing ditch to form a trapezoidal cross-section water flow interception channel structure; Step 2) Connect the water flow interception channel structure to the traditional ditch via an L-shaped pipe (5) at the cross-section of the runoff interface (7); Step 3) Connect the external water flow interception channel to the traditional ditch through a three-way valve at the outlet / inlet (8) of the water flow interception channel structure; Step 4) During the period of high-load pulse phosphorus pollution from agricultural non-point sources, biochar-loaded nano-zero-valent iron material is pre-filled into strip-shaped bags made of biodegradable plastic non-woven fabric. Step 5) Based on the water level and flow velocity, select L-shaped pipes (5) with different vertical L sides to adjust the water level. At the same time, cut off the water outlet of the traditional ditch. After the water body flows into the water flow interception channel structure under atmospheric pressure, adjust the angle between the flow guide interception plate (3) and the side plate (2) of the water flow interception channel according to the flow velocity. Utilize the viscosity and eddy effect of water, the flow velocity of the water body slows down at the flow guide interception plate (3). Particulate phosphorus is intercepted and precipitated step by step, while water-soluble phosphorus is effectively fixed under the strong adsorption of the nano zero-valent iron material supported by biochar. Step 6) After the agricultural non-point source pollution pulse high load phosphorus pollution interception is completed, switch the three-way valve at the discharge / inlet (8) of the water flow interception channel structure so that the water of the regular ditch can directly enter the water flow interception channel structure from the discharge / inlet (8) for backwashing. The particulate phosphorus intercepted during the interception process is backwashed to the cross-sectional runoff interface (7). At the same time, reduce the vertical L side height of the L-shaped pipe (5), change the L-shaped pipe (5) at the cross-sectional runoff interface (7) to a low-position pipe, and put a nutrient collection bag made of biodegradable non-woven material on the horizontal L side of the L-shaped pipe (5) to collect particulate phosphorus through the nutrient collection bag. Step 7) Return the nutrient collection bag and the collected granular phosphorus directly to the field, and use the nutrient adsorption and recovery bag (4) and the collected water-soluble phosphorus as the basic raw materials for developing carbon-based phosphorus-rich and iron-rich compost or organic fertilizer.

6. The method for end-of-pipe interception of high-load phosphorus pollution from agricultural non-point source pulses according to claim 5, characterized in that, In step 4): The biodegradable plastic nonwoven fabric is made of PLA and PBAT materials, and is produced using a pulp airflow process, ensuring that its fiber diameter meets the requirement of 20±5μm and its unit area weight meets the requirement of 120±10g / m². 2 And use a 2mm roller needle to punch holes, so that the hole density is 4 holes per square centimeter, forming a biodegradable plastic non-woven fabric web; The biochar-supported zero-valent iron nanoparticles were prepared from wheat straw, rice straw, and corn straw. The straw was crushed to 5-8 cm and then pyrolyzed at 450°C to obtain biochar. Zero-valent iron nanoparticles were then prepared using a liquid-phase reduction method, resulting in an average particle size of 50 nm, a purity of 99.9%, and a specific surface area of ​​20 m² / g. 2 / g, bulk density 2.3 g / cm³ 3 During the loading process, nitrogen gas is used for protection, and magnetic separation is used for separation. The separated biochar-loaded nano-zero-valent iron material is then washed with deoxygenated water and dried, packed into plastic sealed bags, and filled with nitrogen gas for protection for later use, ensuring that the amount of nano-zero-valent iron loaded in each 1 kg of biochar is not less than 35.0 g.

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