Ecological rural ditch nitrogen and phosphorus interception system and method

Abstract

The invention discloses an ecological rural ditch nitrogen and phosphorus interception system and method, belongs to the technical field of agricultural non-point source pollution control and water environment treatment, and provides an innovative'buffer-purification-interception 'composite ecological rural ditch nitrogen and phosphorus interception technology. By optimizing the ditch design and the ecological structure, the ecological function of the ditch is enhanced, and pollutants such as nitrogen and phosphorus in farmland drainage are efficiently intercepted and purified by removing nitrogen and phosphorus in a multi-level manner.

Description

Technical Field

[0001] The invention relates to the technical field of agricultural non-point source pollution control and water environment management, and in particular to an ecological rural ditch nitrogen and phosphorus interception system and method. Background Art

[0002] Eco-ditch technology is a sewage treatment method that mimics natural wetlands. Its core principle is to effectively intercept and degrade nutrients such as nitrogen and phosphorus in farmland drainage through physical, chemical and biological processes in the ditch. In this process, aquatic plants in the ditch and microbial communities in the sediment play a vital role. The roots of aquatic plants can not only directly absorb pollutants such as ammonia nitrogen, nitrate nitrogen and phosphorus, but also accelerate the transfer of pollutants to sediments by promoting exchange reactions on the interface, thereby improving the interception capacity of the ditch. In China, with the large-scale construction and reconstruction of eco-ditches, their role in the interception and treatment of non-point source sewage has become increasingly prominent.

[0003] However, the existing technology also has the following problems: 1. Limited removal efficiency. The removal efficiency of ordinary ecological ditches for nitrogen and phosphorus pollutants is usually around 70%, which is mainly limited by the plant biomass, contact area, reaction efficiency and water residence time in the ditch; when the adsorption in the ditch reaches saturation, the treatment efficiency will decrease accordingly; 2. Risk of secondary pollution. In ordinary ecological ditches, the adsorbed and absorbed pollutants have not been thoroughly treated. Under extreme weather conditions, such as heavy rain or floods, pollutants may be released in reverse through leaching or alienation, causing secondary pollution of water bodies and farmland; 3. The ecological function is not fully utilized. Ordinary ecological ditches have not yet achieved organic integration with farmland, ridges, ponds, roads and other elements, and have failed to give full play to their ecological functions in the construction of beautiful villages and green ecological corridors.

[0004] Chinese patent document CN111573975A discloses an ecological ditch for farmland drainage with the function of purifying nitrogen and phosphorus, including an ecological ditch main body and a wetland, wherein an artificial drainage channel 1 is arranged on one side of the ecological ditch main body, and an artificial drainage channel 2 is arranged on the other side of the ecological ditch main body, a filter dam 1 is arranged on one side of the ecological ditch main body, and a filter dam 2 is arranged on the other side of the ecological ditch main body. The beneficial effect lies in that: through the design of the ecological ditch main body, filter dam 1, filter dam 2, artificial drainage channel 1, artificial drainage channel 2 and wetland, the present invention can not only slow down the flow speed of farmland sewage while ensuring the normal circulation of farmland sewage, ensure that the nitrogen and phosphorus in the farmland sewage can be fully adsorbed and converted, effectively improve the drainage quality of farmland, and reduce water pollution, but also enable the ecological ditch to be transferred and opened according to actual conditions, with flexible usage and good practicality. This patent mainly utilizes aquatic plants and pink-green foxtail algae to remove nitrogen and phosphorus at a single level. The removal efficiency of aquatic plants and pink-green foxtail algae is affected by many factors such as climate, environment, and nutrient supply, and cannot guarantee sufficient adsorption and conversion of nitrogen and phosphorus in agricultural wastewater. Summary of the invention

[0005] The main purpose of the present invention is to address the problems of insufficient functions of existing farmland ecosystems and limited ditch interception and purification capabilities, and to propose an innovative "buffering-purification-interception" composite ecological rural ditch nitrogen and phosphorus interception technology. Without interfering with normal farmland production activities, the ditch design and ecological structure are optimized to enhance its ecological function, and nitrogen and phosphorus are removed at multiple levels to achieve efficient interception and purification of pollutants such as nitrogen and phosphorus in farmland drainage.

[0006] To achieve the above-mentioned purpose, the present invention proposes an ecological rural ditch nitrogen and phosphorus interception system, comprising a ditch arranged along the direction of water flow, wherein the ditch comprises a first ditch bottom, a second ditch bottom, a third ditch bottom and revetments on both sides, and the ditch is sequentially connected with a sediment buffer zone, a purification unit, an interception conversion pool and a pebble hedge fence; farmland drainage is preliminarily treated in the sediment buffer zone to precipitate sediments, and then enters the purification unit for treatment to remove nitrogen and phosphorus pollutants in the water body, and then flows through the interception conversion pool for deep treatment to reduce the nitrogen and phosphorus content in the water, and finally flows through the pebble hedge fence to achieve the final interception and removal of nitrogen and phosphorus pollutants.

[0007] Preferably, the sediment buffer zone includes a slope water drop zone, a buffer flow regulating wall and flow holes, the slope water drop zone is arranged at the front end of the ditch and connected to the first ditch bottom; the buffer flow regulating wall is fixed on the first ditch bottom; and a plurality of flow holes are arranged on the buffer flow regulating wall.

[0008] Further preferably, the buffer flow regulating wall has a thickness of 20-30 cm and a number thereof ≥1.

[0009] Preferably, the purification unit comprises a nitrification-denitrification-phosphorus removal treatment device and an aquatic plant community unit, the nitrification-denitrification-phosphorus removal treatment device is installed on the second ditch bottom; the aquatic plant community unit is located downstream of the nitrification-denitrification-phosphorus removal treatment device.

[0010] Further preferably, the nitrification-denitrification-phosphorus removal treatment device is provided with a plant growth bag module, an iron-manganese composite oxide film module, a denitrification module, and a phosphorus adsorption medium module in sequence.

[0011] Further preferably, the phosphorus adsorption medium module is provided with a phosphorus adsorption medium, and the preparation method of the phosphorus adsorption medium is as follows:

[0012] (1) The straw is naturally air-dried, non-biological impurities are cleaned, and then crushed and passed through a 40-80 mesh sieve; the crushed and sieved straw and montmorillonite are dispersed in water, lanthanum nitrate pentahydrate is added, mixed and stirred evenly, and then a hydrothermal reaction is carried out. After the reaction is completed, the mixture is cooled to room temperature, filtered, and then immersed in dilute sulfuric acid to obtain composite biochar;

[0013] (2) dispersing the composite biochar in an ethanol aqueous solution, adding mercaptopropyltrimethoxysilane, stirring and reacting at room temperature for 2-4 hours, filtering, and drying to obtain the thiolated biochar;

[0014] (3) Dispersing the thiolated biochar in water, adding guar gum hydroxypropyltrimethylammonium chloride, adjusting the pH value to 3-4 with aqueous hydrochloric acid solution, heating the reaction for 4-6 hours, cooling to room temperature after the reaction is completed, filtering, washing, drying, and grinding to obtain a phosphorus adsorption medium.

[0015] Preferably, in step (1), the mass ratio of straw, montmorillonite and lanthanum nitrate pentahydrate is 30-50:15-25:5-10; and the hydrothermal reaction temperature is 200-300°C.

[0016] Preferably, in step (2), the mass ratio of the composite biochar to mercaptopropyltrimethoxysilane is 30-50:1-5.

[0017] Preferably, in step (3), the mass ratio of thiolated biochar to guar gum hydroxypropyltrimethylammonium chloride is 15-25:3-8, and the reaction temperature is 50-80°C.

[0018] Further preferably, the aquatic plant community unit includes a slope support and a support net, and emerging plants are planted on the revetments on both sides of the aquatic plant community unit, and submerged plants are planted at the bottom; the slope support is located on the ditch, and a support net is arranged on the slope support; the emerging plants are a mixture of water celery, watercress, Bermuda, Manila, tall fescue, and jade dragon grass.

[0019] Preferably, a water collection area, an adsorption and interception area, and a water storage and drainage area are sequentially arranged in the interception and conversion pool along the water flow direction.

[0020] Preferably, the pebble fence is arranged along the end of the ditch.

[0021] Preferably, a pebble belt is provided at the bottom of the pebble fence and is planted with emerging plants and submerged plants.

[0022] Compared with the prior art, the advantages and beneficial effects of the present invention are:

[0023] 1. Without interfering with the normal production of farmland, the present invention fully explores and enhances its ecological potential, and builds farmland into an effective assimilation center of environmental nitrogen and phosphorus. Through this innovative approach, we aim to purify the quality of farmland drainage water and comprehensively improve the ecological environment of farmland. Faced with the challenges of insufficient functions of existing farmland ecosystems and limited ditch purification capacity, this solution comprehensively optimizes and upgrades the "field ridge ditch pond road" system, which not only enriches the biodiversity and ecological buffering capacity of farmland, but also improves the beautification effect and economic value of field ridges;

[0024] 2. The present invention pays special attention to improving the environmental landscape effect and self-purification ability of water bodies to meet the needs of beautiful rural construction. By constructing green ecological corridors, it injects new vitality into the sustainable development of agriculture and is committed to achieving harmonious coexistence between agricultural production and ecological environment protection;

[0025] 3. The present invention can achieve efficient chemical adsorption and removal of phosphorus by adding a special phosphorus adsorption medium into the nitrification-denitrification-phosphorus removal treatment device; and improve the interception capacity of the ecological rural ditch nitrogen and phosphorus interception system for nitrogen and phosphorus pollutants in farmland drainage. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 This is a schematic diagram of the structure of the ecological rural ditch nitrogen and phosphorus interception system of the present invention;

[0028] Figure 2 It is a schematic plan view of the ecological rural ditch nitrogen and phosphorus interception system of the present invention;

[0029] Figure 3 It is a cross-sectional view of the aquatic plant community unit 1-1 of the present invention;

[0030] Figure 4 It is a cross-sectional view of the interception conversion tank 2-2 of the present invention;

[0031] Figure 5 It is a cross-sectional view of the pebble fence 3-3 of the present invention.

[0032] Explanation of the reference numerals in the figure: 1-ditch; 11-first ditch bottom; 12-second ditch bottom; 13-third ditch bottom; 14-bank protection; 2-sediment buffer zone; 21-slope water drop zone; 22-buffer flow regulating wall; 23-flow hole; 3-purification unit; 31-nitrification-denitrification-phosphorus removal treatment device; 32-aquatic plant community unit; 321-emerging plants; 322-slope protection support; 323-support net; 324-submerged plants; 4-retention conversion pool; 41-water collection area; 42-adsorption interception area; 421-carbon-based filler wall; 43-water storage and drainage area; 5-pebble fence; 51-pebble belt. DETAILED DESCRIPTION

[0033] To make the purpose, technical scheme and advantages of the embodiment of the present invention clearer, the technical scheme in the embodiment of the present invention will be clearly and completely described below. If the specific conditions are not specified in the embodiment, it is carried out according to the normal conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified in the reagents or instruments used, they are all conventional products that can be purchased commercially. In addition, the technical schemes between the various embodiments can be combined with each other, but must be based on the ability of ordinary technicians in the field to achieve. When the combination of technical solutions is contradictory or cannot be achieved, it should be considered that the combination of such technical solutions does not exist, and is not within the scope of protection required by the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work belong to the scope of protection of the present invention.

[0034] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments and drawings. It should be understood that the following embodiments are only used to explain the present invention and are not used to limit the present invention.

[0035] In view of the low efficiency of removing nitrogen and phosphorus pollutants in ecological ditches in the prior art, the existence of secondary pollution and the underutilization of ecological functions, the present invention proposes an ecological rural ditch nitrogen and phosphorus interception system and method, referring to Figure 1-5 , Figure 1 This is a schematic diagram of the structure of the ecological rural ditch nitrogen and phosphorus interception system of the present invention; Figure 2 It is a schematic plan view of the ecological rural ditch nitrogen and phosphorus interception system of the present invention; Figure 3 It is a cross-sectional view of the aquatic plant community unit 1-1 of the present invention; Figure 4 It is a cross-sectional view of the interception conversion tank 2-2 of the present invention;

[0036] Figure 5 The cross-sectional view of the pebble fence 3-3 of the present invention is shown in FIG.

[0037] Example 1

[0038] like Figure 1 and Figure 3 As shown, an ecological rural ditch nitrogen and phosphorus interception system includes a ditch 1 arranged along the water flow direction, wherein the ditch 1 includes a first ditch bottom 11, a second ditch bottom 12, a third ditch bottom 13 and revetments 14 on both sides, and the ditch 1 is sequentially connected with a sediment buffer zone 2, a purification unit 3, an interception conversion pool 4 and a pebble fence 5; farmland drainage is initially treated in the sediment buffer zone 2 to precipitate sediments and then enters the purification unit 3 to remove nitrogen and phosphorus pollutants in the water body, then flows through the interception conversion pool 4 for deep treatment to reduce the nitrogen and phosphorus content in the water, and finally flows through the pebble fence 5 to achieve the final interception and removal of nitrogen and phosphorus pollutants.

[0039] In view of the problems of insufficient functions of farmland ecosystems and limited interception and purification capacity of ditches in the prior art, an ecological rural ditch nitrogen and phosphorus interception technology is proposed. By setting a sediment buffer zone 2, water flow can be preliminarily treated, sediments can be precipitated, and the solid particles and pollutant loads in the water can be effectively reduced; by setting a purification unit 3, nitrogen and phosphorus pollutants in the water body can be further removed through the synergistic effect of microorganisms and plants; by setting an interception conversion pool 4, it is used to deeply treat farmland drainage to further reduce the nitrogen and phosphorus content in the water; by setting a pebble fence 5, unprecipitated or untreated nitrogen and phosphorus pollutants can be further removed to ensure the quality of the water before outflow; the present invention optimizes the ditch design and ecological structure to enhance its ecological function, and removes nitrogen and phosphorus at multiple levels to achieve efficient interception and purification of pollutants such as nitrogen and phosphorus in farmland drainage.

[0040] The sediment buffer zone 2 includes a slope water drop area 21, a buffer flow regulating wall 22 and a flow hole 23. The slope water drop area 21 is arranged at the front end of the ditch 1 and is connected to the first ditch bottom 11; the buffer flow regulating wall 22 is fixed on the first ditch bottom 11, which can effectively slow down the water flow speed and promote sediment settlement; a plurality of flow holes 23 are arranged on the buffer flow regulating wall 22; and the hole density of the flow holes 23 decreases from top to bottom, which is used to finely control the water flow; submerged plants 324 are also planted in the sediment buffer zone 2; the submerged plants 324 are a variety of mixed species of black algae, bitter algae, duckweed, and duckweed.

[0041] Further preferably, the buffer flow regulating wall 22 has a thickness of 20-30 cm and a height of one half to three quarters of the height from the first ditch bottom 11 to the ditch top, and the number thereof is ≥ 1, ensuring sufficient strength and effective water flow regulation. Multiple walls can form multi-stage filtration, increasing the processing area and improving the sedimentation effect, thereby ensuring effective regulation of the water flow.

[0042] Preferably, the purification unit 3 includes a nitrification-denitrification-phosphorus removal treatment device 31 and an aquatic plant community unit 32. The nitrification-denitrification-phosphorus removal treatment device 31 is installed on the second ditch bottom 12 to remove nitrogen and phosphorus pollutants; the aquatic plant community unit 32 is located downstream of the nitrification-denitrification-phosphorus removal treatment device 31.

[0043] By combining the nitrification-denitrification-phosphorus removal treatment device 31 with the aquatic plant community unit 32, the purification unit 3 not only greatly improves the removal efficiency of nitrogen and phosphorus, but also promotes the overall stability and biodiversity of the ecosystem, providing an effective solution for water quality protection and improvement.

[0044] Further preferably, the nitrification-denitrification-phosphorus removal treatment device 31 is provided with a water inlet and a water outlet; the water inlet is arranged at the junction with the sediment buffer zone 2 and is flush with the second ditch bottom 12; the water outlet is arranged at the junction with the aquatic plant community unit 32 and is flush with the second ditch bottom 12, and the nitrification-denitrification-phosphorus removal treatment device 31 is sequentially provided with a plant growth bag module, an iron-manganese composite oxide film module, a denitrification module module, and a phosphorus adsorption medium module to achieve multi-level removal of pollutants.

[0045] Preferably, the plant growth bag module is composed of eco-concrete, crushed stone and emergent landscape plants placed in an eco-bag. The emergent landscape plants are used to absorb organic matter and nutrients in farmland drainage as nutrients; at the same time, the transfer and release of oxygen by the plant roots is used to make the surrounding microenvironment present aerobic-anoxic-anaerobic in sequence, and through nitrification-denitrification and excessive accumulation of phosphorus by microorganisms, some nitrogen and phosphorus pollutants are intercepted and removed; the emergent landscape plants are one or more mixed species of reed, cattail, water plantain, lotus, water lily, water celery, and water fern.

[0046] Preferably, the iron-manganese composite oxide film module is composed of polyhedral hollow balls and gravel built into an eco-bag, wherein the polyhedral hollow balls are attached with an iron-manganese oxide film; the oxidation performance and adsorption capacity of the iron-manganese composite oxide film catalyze the oxidation of ammonia nitrogen in the water to achieve further removal effect; the adsorbed ammonia nitrogen is subsequently oxidized into nitrate and nitrite and enters the water.

[0047] Preferably, the denitrification module is composed of polyhedral hollow balls and gravel built into an eco-bag, wherein the polyhedral hollow balls are attached to or filled with denitrification substrates. The denitrifying bacteria enriched in the denitrification module utilize the nitrate and nitrite produced in the early stage as electron donors to perform denitrification and reduce nitrate nitrogen into nitrogen gas.

[0048] Preferably, the phosphorus adsorption medium module is composed of polyhedral hollow balls and crushed stones built into an eco-bag, wherein the polyhedral hollow balls are attached to or filled with phosphorus adsorption medium.

[0049] Preferably, the preparation method of the phosphorus adsorption medium is as follows:

[0050] (1) The straw was naturally air-dried, non-biological impurities were cleaned, and then crushed and passed through a 60-mesh sieve; 80 g of the crushed and sieved straw and 40 g of montmorillonite were dispersed in 500 mL of water, 16 g of lanthanum nitrate pentahydrate was added, the mixture was mixed and stirred evenly, and then a hydrothermal reaction was carried out at 250 ° C. The hydrothermal reaction time was 20 h. After the reaction was completed, it was cooled to room temperature, filtered, and immersed in 500 mL of 15 wt% dilute sulfuric acid for 8 h, filtered, and the solid matter was collected, washed with water until the filtrate was neutral, and dried to obtain composite biochar;

[0051] (2) 80 g of the composite biochar was dispersed in 500 mL of a 50 wt% ethanol aqueous solution, 6.2 g of mercaptopropyltrimethoxysilane was added, and the mixture was stirred at room temperature for 3 h. The solid was filtered and dried to obtain the thiolated biochar;

[0052] (3) Disperse 60 g of thiolated biochar in 500 mL of water, add 15 g of guar hydroxypropyltrimethylammonium chloride, adjust the pH value to 3.5 with 1 mol / L hydrochloric acid, heat the reaction at 60 °C for 5 h, cool to room temperature after the reaction is completed, filter, wash, dry, and grind to obtain a phosphorus adsorption medium.

[0053] The phosphorus adsorption medium of the present invention is prepared by firstly reacting straw, montmorillonite and lanthanum nitrate pentahydrate under hydrothermal conditions, wherein lanthanum nitrate can in situ generate lanthanum oxide capable of adsorbing organic phosphorus in biochar generated by montmorillonite and straw, and compared with direct physical mixing, lanthanum oxide has better distribution and better binding force in composite biochar, which is beneficial to improving the adsorption performance of composite biochar on phosphorus; then, its functional groups are activated under acidic conditions, and thiol groups are introduced into the composite biochar to further improve its reaction activity, and guar gum hydroxypropyl trimethyl ammonium chloride is grafted onto the surface of composite biochar through the reaction of thiol groups and guar gum hydroxypropyl trimethyl ammonium chloride, which is not easy to fall off, and on the one hand, the hydrophilicity of biochar can be improved, and on the other hand, the positive charge carried by guar gum hydroxypropyl trimethyl ammonium chloride can adsorb negatively charged phosphate and organic phosphorus in water, and further improve the interception effect of the phosphorus adsorption medium on phosphorus, and no secondary pollution will be caused.

[0054] By setting different modules, the nitrification-denitrification-phosphorus removal treatment device 31 can remove nitrogen, phosphorus and other pollutants in the water in stages to improve the overall water purification effect. The plant growth bag module provides a good growth environment for aquatic plants, and the roots of the plants can further absorb nutrients in the water, promote the self-purification function of the water body, and provide a habitat for organisms to improve ecological diversity; the iron-manganese composite oxide film can undergo redox reactions with harmful substances in the water, promote the removal of pollutants, and provide a larger surface area for the reaction, thereby improving the overall reaction efficiency; the denitrification module reduces nitrates to nitrogen gas to achieve nitrogen removal; and the phosphorus adsorption medium effectively removes phosphorus from the water body; the design of the water inlet and outlet flush with the bottom of the ditch can achieve a relatively stable flow rate, avoid violent fluctuations that affect the treatment effect, and make the water flow evenly distributed in the treatment device.

[0055] More preferably, Figure 2 The 1-1 cross-sectional view of the aquatic plant community unit 32 is as follows Figure 3 As shown, the aquatic plant community unit 32 includes a slope support 322 and a support net 323, and emerging plants 321 are planted on the revetments 14 on both sides of the aquatic plant community unit 32, and submerged plants 324 are planted at the bottom thereof; the slope support 322 is located on the revetment 14, and a support net 323 is arranged on the slope support 322, and a stable growth foundation is provided for the emerging plants 321 through the support of the slope support 322 and the dense support net 323; the emerging plants 321 are a variety of hybrids of water celery, watercress, Bermuda, Manila, tall fescue, and jade dragon grass.

[0056] Preferably, the bottom of the aquatic plant community unit 32 is higher than the second ditch bottom 12, so that the nitrification-denitrification-phosphorus removal treatment device 31 can form a "sedimentation tank" effect, which is conducive to the precipitation of suspended matter in the water body. This can not only purify the water quality, but also prevent the emerging plants 321 from being damaged by mud and sand.

[0057] Further preferably, the support net 323 is woven with environmentally friendly materials, and the side length of the support grid is 20-30 cm, providing a stable support for the emerging plants 321.

[0058] Preferably, Figure 1 As shown, a water inlet, a water collection area 41, an adsorption interception area 42, a water storage and drainage area 43 and a water outlet are sequentially arranged in the interception conversion pool 4 along the water flow direction; the water inlet is arranged at the junction of the interception conversion pool 4 and the purification unit 3 and is flush with the third ditch bottom 13; the water outlet is arranged at the tail end of the interception conversion pool 4 and is flush with the third ditch bottom 13; the water collection area 41, the adsorption interception area 42, the water storage and drainage area 43 are sequentially arranged between the water inlet and the water outlet.

[0059] In order to further remove nitrogen and phosphorus pollutants in farmland drainage, an interception and conversion pool 4 is set up in the ecological rural ditch nitrogen and phosphorus interception system, wherein the water collection area 41 can accumulate a large amount of water, adjust the water flow rate, reduce the peak flow, and avoid scouring and damage to the purification unit 3; the adsorption interception area 42 can effectively adsorb pollutants in the water, reduce water pollution, and improve the water quality of the outlet; the water storage and drainage area 43 can allow heavier solid particles to precipitate, to a certain extent realize the separation of solid matter in the water, and further purify the water body; and the inlet and outlet flush with the ditch bottom can ensure the smooth entry and discharge of water.

[0060] Further preferably, the volume of the interception conversion pool 4 is 1.5-3 cubic meters; the interception conversion pool 4 in the volume range can promote the deceleration of water flow, increase the sedimentation time, improve the sedimentation efficiency of suspended matter and sediment in the water, and improve the water treatment effect.

[0061] More preferably, the third ditch bottom 13 is lower than the bottom of the aquatic plant community unit 32, which can improve the working efficiency of the interception conversion pool 4, is conducive to utilizing the gravity of the water flow itself to achieve effective flow of the water flow, and promotes the sedimentation and adsorption of pollutants.

[0062] Further preferably, a carbon-based filler wall 421 is provided in the adsorption interception zone 42; the carbon-based filler has good adsorption properties, can effectively remove organic matter, heavy metals and other pollutants in water, and can promote the growth of aerobic and anaerobic microorganisms, and enhance the nitrogen and phosphorus interception effect in the water.

[0063] Further preferably, the carbon-based filler wall 421 is designed as a porous frame and sponge layer. The porous frame structure and sponge design enhance the stability and pressure resistance of the overall structure, and can effectively retain water flow, so that pollutants have enough time to be adsorbed and degraded during the flow process.

[0064] More preferably, the carbon-based filler wall 421 has a thickness of 40-60 cm, and the top is higher than the bottom of the ditch to ensure sufficient contact and removal of pollutants.

[0065] More preferably, Figure 2 The 2-2 cross-sectional view of the interception conversion tank 4 is as shown in FIG. Figure 4 As shown, new plants 321 are planted on the revetment 14 of the interception conversion pool 4, which can further remove nitrogen and phosphorus pollutants.

[0066] Preferably, according to Figure 2 3-3 cross-sectional view of pebble fence 5 Figure 5 As shown, the bottom of the pebble fence 5 is provided with a pebble belt 51 and planted with emerging plants 321 and submerged plants 324, which not only enhances the ecological function but also adds beauty to the rural landscape.

[0067] Preferably, the width of the pebble belt 51 is 0.3-0.5 meters, and pebbles with a particle size of 3-10 cm are laid, maintaining a slope of 3-10%, thereby enhancing the self-purification ability of the water flow.

[0068] Example 2

[0069] A water purification method using the above-mentioned ecological rural ditch nitrogen and phosphorus interception system, the specific steps are as follows:

[0070] The farmland drainage first passes through the sediment buffer zone 2, and uses the slope water drop area 21 and the buffer flow regulating wall 22 to slow down the flow rate and promote sediment sedimentation, and the water flow and submerged plants 324 are finely regulated by the flow holes 23 set on the buffer flow regulating wall 22 to perform preliminary purification on the drainage; then the drainage enters the purification unit 3, and the nitrogen and phosphorus pollutants are biochemically removed by the plant growth bag module, iron-manganese composite oxide film module, denitrification module module, and phosphorus adsorption medium module in the nitrification-denitrification-phosphorus removal treatment device 31, and then the emerging plants 321 and submerged plants 324 in the aquatic plant community unit 32 absorb the nitrogen and phosphorus pollutants in the water body; the treated water flow then enters the interception conversion tank 4, and is adsorbed and precipitated by the carbon-based filler wall 421 to achieve further removal of pollutants; the clean water flow leaves the interception conversion tank 4 and continues to flow to the pebble fence 5, and finally removes the nitrogen and phosphorus pollutants through the emerging plants 321 and submerged plants 324.

[0071] Comparative Example 1

[0072] An ecological rural ditch nitrogen and phosphorus interception system is similar to Example 1, except that the phosphorus adsorbent medium used is obtained by reacting composite biochar with guar gum hydroxypropyltrimethylammonium chloride. The specific preparation method is as follows:

[0073] (1) The straw was naturally air-dried, non-biological impurities were cleaned, and then crushed and passed through a 60-mesh sieve; 80 g of the crushed and sieved straw and 40 g of montmorillonite were dispersed in 500 mL of water, 16 g of lanthanum nitrate pentahydrate was added, the mixture was mixed and stirred evenly, and then a hydrothermal reaction was carried out at 250 ° C. The hydrothermal reaction time was 20 h. After the reaction was completed, it was cooled to room temperature, filtered, and immersed in 500 mL of 15 wt% dilute sulfuric acid for 8 h, filtered, and the solid matter was collected, washed with water until the filtrate was neutral, and dried to obtain composite biochar;

[0074] (2) Disperse 60 g of composite biochar in 500 mL of water, add 15 g of guar hydroxypropyltrimethylammonium chloride, adjust the pH value to 3.5 with 1 mol / L hydrochloric acid, heat the reaction at 60 °C for 5 h, cool to room temperature after the reaction is completed, filter, wash, dry, and grind to obtain a phosphorus adsorption medium.

[0075] Comparative Example 2

[0076] An ecological rural ditch nitrogen and phosphorus interception system is similar to Example 1, except that the phosphorus adsorbent medium used is composite biochar, and its preparation method is as follows:

[0077] The straw was naturally air-dried, non-biological impurities were cleaned, and then crushed and passed through a 60-mesh sieve; 80 g of the crushed and sieved straw and 40 g of montmorillonite were dispersed in 500 mL of water, 16 g of lanthanum nitrate pentahydrate was added, the mixture was stirred evenly, and then a hydrothermal reaction was carried out at 250°C for 20 hours. After the reaction was completed, the mixture was cooled to room temperature, filtered, and immersed in 500 mL of 15 wt% dilute sulfuric acid for 8 hours, filtered, the solid matter was collected, washed with water until the filtrate was neutral, and dried to obtain composite biochar.

[0078] Test Case

[0079] 10 g of each of the phosphorus adsorption media prepared in Example 1, Comparative Example 1 and Comparative Example 2 were added to 50 mL of a phosphorus standard solution (pH = 5.8) with a concentration of 10 mg / L in terms of phosphorus element, and oscillated at a constant temperature of 25 ° C for 4 h with an oscillation frequency of 140 r / min. The phosphorus removal rate was calculated. The experimental results are shown in Table 1:

[0080] Table 1 Phosphorus removal rate test results of phosphorus adsorption media

[0081] Phosphorus removal rate (%) Example 1 95.6 Comparative Example 1 90.3 Comparative Example 2 85.2

[0082] The above are only preferred embodiments of the present invention, and do not limit the patent scope of the present invention. For those skilled in the art, the present invention may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the patent protection scope of the present invention.

Claims

1. An ecological rural ditch nitrogen and phosphorus interception system, comprising a ditch (1) arranged along the water flow direction, characterized in that: The ditch (1) comprises a first ditch bottom (11), a second ditch bottom (12), a third ditch bottom (13) and revetments (14) on both sides. The ditch (1) is sequentially connected with a sediment buffer zone (2), a purification unit (3), an interception conversion pool (4) and a pebble fence (5); farmland drainage is initially treated in the sediment buffer zone (2) to precipitate sediments, then enters the purification unit (3) to remove nitrogen and phosphorus pollutants in the water body, then flows through the interception conversion pool (4) to perform deep treatment to reduce the nitrogen and phosphorus content in the water, and finally flows through the pebble fence (5) to achieve final interception and removal of nitrogen and phosphorus pollutants.

2. The interception system according to claim 1, characterized in that: The sediment buffer zone (2) comprises a slope water drop zone (21), a buffer flow regulating wall (22) and flow holes (23); the slope water drop zone (21) is arranged at the front end of the ditch (1) and connected to the first ditch bottom (11); the buffer flow regulating wall (22) is fixed on the first ditch bottom (11); and a plurality of flow holes (23) are arranged on the buffer flow regulating wall (22).

3. The interception system according to claim 1, characterized in that: The purification unit (3) comprises a nitrification-denitrification-phosphorus removal treatment device (31) and an aquatic plant community unit (32); the nitrification-denitrification-phosphorus removal treatment device (31) is installed on the second ditch bottom (12); and the aquatic plant community unit (32) is located downstream of the nitrification-denitrification-phosphorus removal treatment device (31).

4. The interception system according to claim 3, characterized in that: The nitrification-denitrification-phosphorus removal treatment device (31) is provided with a plant growth bag module, an iron-manganese composite oxide film module, a denitrification module, and a phosphorus adsorption medium module in sequence.

5. The interception system according to claim 4, characterized in that The phosphorus adsorption medium module is provided with a phosphorus adsorption medium, and the preparation method of the phosphorus adsorption medium is as follows: (1) The straw is naturally air-dried, non-biological impurities are cleaned, and then crushed and passed through a 40-80 mesh sieve; the crushed and sieved straw and montmorillonite are dispersed in water, lanthanum nitrate pentahydrate is added, mixed and stirred evenly, and then a hydrothermal reaction is carried out. After the reaction is completed, the mixture is cooled to room temperature, filtered, and then immersed in dilute sulfuric acid to obtain composite biochar; (2) dispersing the composite biochar in an ethanol aqueous solution, adding mercaptopropyltrimethoxysilane, stirring and reacting at room temperature for 2-4 hours, filtering, and drying to obtain the thiolated biochar; (3) Dispersing the thiolated biochar in water, adding guar gum hydroxypropyltrimethylammonium chloride, adjusting the pH value to 3-4 with dilute hydrochloric acid, heating the reaction for 4-6 hours, cooling to room temperature after the reaction is completed, filtering, washing, drying, and grinding to obtain a phosphorus adsorption medium.

6. The interception system according to claim 3, characterized in that: The aquatic plant community unit (32) comprises a slope protection support (322) and a support net (323), and emerging plants (321) are planted on the revetments (14) on both sides of the aquatic plant community unit (32), and submerged plants (324) are planted at the bottom thereof; the slope protection support (322) is located on the revetment (14), and a support net (323) is arranged on the slope protection support (322); the emerging plants (321) are a variety of mixed species selected from water celery, watercress, Bermuda, Manila, tall fescue, and jade dragon grass.

7. The interception system according to claim 1, characterized in that: A water collection area (41), an adsorption interception area (42) and a water storage and drainage area (43) are sequentially arranged in the interception conversion pool (4) along the water flow direction.

8. The interception system according to claim 7, characterized in that: A carbon-based filler wall (421) is provided in the adsorption interception zone (42).

9. The interception system according to claim 1, characterized in that: The pebble fence (5) is arranged along the end of the ditch (1).

10. The interception system according to claim 9, characterized in that: The bottom (5) of the pebble fence is provided with a pebble belt (51) and is planted with emerging plants (321) and submerged plants (324).

Images