A device for simultaneously recovering nitrogen and phosphorus in sewage by electrically driving struvite crystallization and precipitation

Abstract

The utility model belongs to sewage treatment technical field, especially relates to a device of synchronous recovery of sewage nitrogen and phosphorus of electric drive struvite crystallization precipitation, it solves how to continuously realize the problem of nitrogen and phosphorus treatment of rural sewage.This electric drive struvite crystallization precipitation synchronous recovery of sewage nitrogen and phosphorus device, including reactor, the reactor is formed with reaction cavity, is equipped with N pairs of soluble anode and inert cathode in the reaction cavity, N >= 1, the soluble anode is made of magnesium, and the inert cathode is stainless steel, the soluble anode is connected with the positive terminal of polarity reversal DC power supply, the inert cathode is connected with the negative terminal of polarity reversal DC power supply, and the positive terminal and the negative terminal can reverse polarity simultaneously.The effect that nitrogen and phosphorus are recycled in the form of struvite is realized, and the re-addition of chemical medicine is avoided through the mode of electric drive magnesium ion release, secondary pollution is avoided, and operation and maintenance cost is also reduced.

Description

Technical Field

[0001] This utility model belongs to the field of wastewater treatment technology, and specifically relates to a device for simultaneously recovering nitrogen and phosphorus from wastewater through electrically driven struvite crystallization and precipitation. Background Technology

[0002] As the living standards of rural residents have improved year by year, the nitrogen and phosphorus content of rural sewage has also increased sharply. Its nitrogen and phosphorus emissions account for more than 49% and 25% of the total surface water received in rural areas, respectively, which further reduces the carbon-nitrogen ratio and carbon-phosphorus ratio of rural sewage.

[0003] Traditional urban wastewater treatment plants, such as A2 / O, often use biological nitrogen and phosphorus removal processes. However, due to the high difficulty in operation and management, these processes are difficult to operate effectively and stably in rural areas, and they also cannot meet the current demand for the removal of new pollutants in domestic sewage.

[0004] Through continuous exploration, existing technologies have proposed methods or devices for converting nitrogen and phosphorus into struvite through electrochemical means to achieve nitrogen and phosphorus recovery. However, most of these methods cannot effectively remove the oxide film on the sacrificial anode made of magnesium. As the reaction continues, the oxide film coats the surface of the sacrificial anode, affecting the generation of magnesium ions, increasing energy consumption, and may even cause the reaction to stop, affecting the continuous stability of wastewater treatment. Summary of the Invention

[0005] The purpose of this invention is to address the aforementioned problems in the existing technology by proposing an electrically driven struvite crystallization and precipitation device for the simultaneous recovery of nitrogen and phosphorus from wastewater.

[0006] To achieve the innovative objectives of this utility model, the following technical solutions can be used: A device for simultaneously recovering nitrogen and phosphorus from wastewater through electrically driven struvite crystallization and precipitation includes a reactor. A reaction chamber is formed inside the reactor. N pairs of soluble anodes and inert cathodes are provided in the reaction chamber, where N≥1. The soluble anodes are connected to the positive terminal of a DC power supply with reverse polarity, and the inert cathodes are connected to the negative terminal of the DC power supply with reverse polarity. The positive and negative terminals can simultaneously reverse their polarities.

[0007] This invention is primarily used for the treatment of rural sewage. The water quality characteristics of rural sewage have changed with commercialization. This device mainly treats nitrogen and phosphorus in sewage through electrochemical means, converting them into struvite precipitate for reuse. The reactor in this device provides a specific reaction site, with a soluble anode and an inert cathode inside the reaction chamber. Driven by electrical energy, the soluble anode undergoes an oxidation reaction, where magnesium loses electrons to generate magnesium ions. Magnesium ions, ammonium ions, and phosphate ions combine to form MgNH4PO4·6H2O, i.e., struvite, achieving ammonia nitrogen recovery rate ≥60% and total phosphorus recovery rate ≥90%. The cathode undergoes a hydrogen evolution reaction, where water is electrolyzed to generate hydrogen gas and hydroxide ions. The hydroxide ions increase the pH value of the solution, and the alkaline environment promotes the formation of struvite crystals. Moreover, the reaction is driven by electricity, which means that the generation rate of magnesium ions can be precisely controlled by the current to match different nitrogen and phosphorus concentrations in wastewater, avoiding waste or deficiency. Magnesium ions are generated from soluble anodes, eliminating the need for additional magnesium-containing chemicals, reducing operating costs and the risk of secondary pollution, making it particularly suitable for rural areas with limited operation and maintenance capabilities.

[0008] Furthermore, during normal reaction, the soluble anode is connected to the positive electrode, and the inert cathode is connected to the negative electrode. However, as the reaction continues, magnesium does not completely and uniformly dissolve on the anode surface. Simultaneously, dissolved oxygen or other oxidizing substances in the wastewater partially oxidize the anode surface, forming a dense passivation film of magnesium oxide or magnesium hydroxide. This non-conductive film encapsulates the anode, leading to a sharp increase in electrode resistance, requiring higher voltage to maintain the current and increasing energy consumption. Furthermore, it hinders the release of magnesium ions, reducing the efficiency of struvite formation, and in severe cases, potentially causing system failure and complete cessation of the reaction. Therefore, the positive and negative terminals of this device can be reversed, connecting the soluble anode to the negative electrode (cathode) and the inert cathode to the anode (anode). At this point, a reduction reaction occurs at the soluble anode, where water electrocatalyzes the production of hydrogen and hydroxide ions. These hydroxide ions chemically react with the passivation film, dissolving or destroying it. The hydrogen bubbles physically scour and peel away the passivation film, effectively removing the passivation layer. The inert cathode undergoes an oxidation reaction, which may cause slight corrosion to the motor. However, this state is generally short-lived. The inert cathode is made of corrosion-resistant materials, so the corrosion effect is within a controllable range. The oxygen bubbles generated by the oxidation reaction also help remove deposits such as bird droppings adhering to the inert cathode. Of course, the polarity reversal of the positive and negative terminals can be achieved through a corresponding controller; this is existing technology and will not be further elaborated upon.

[0009] In the above-mentioned device for simultaneous recovery of nitrogen and phosphorus from wastewater by electro-driven struvite crystallization precipitation, the soluble anode comprises magnesium and / or magnesium alloy, and the inert cathode comprises stainless steel.

[0010] In the above-mentioned device for simultaneous recovery of nitrogen and phosphorus from wastewater by electro-driven struvite crystallization precipitation, N≥2, and both the soluble anode and the inert cathode are plate-shaped. The soluble anode and inert cathode are arranged in alternating layers of parallel plates or in alternating concentric cylindrical arrangements.

[0011] Multiple sets of soluble anodes and inert cathodes are arranged alternately, which helps to improve reaction efficiency. The specific arrangement can be linear or circular, depending on the shape of the reaction chamber.

[0012] In the above-mentioned electrically driven struvite crystallization precipitation and simultaneous recovery of nitrogen and phosphorus from wastewater, the reaction chamber is equipped with a stirring structure, which includes stirring blades, and the stirring blades are connected to the stirring driver via a stirring shaft. The stirring structure is disposed between the circularly arranged soluble anode and inert cathode, which are arc-shaped plates and bent along the stirring direction; Alternatively, the stirring structure is disposed below the soluble anode and inert cathode arranged in parallel plates, wherein the soluble anode and inert cathode are in the shape of planar plates. The stirring structure is used to promote the contact between wastewater and soluble anode and inert cathode. In the annular arrangement, the stirring blades are set inside the annulus, and the electrodes are arc-shaped with each arc located on the same circle, which is beneficial to the stirring and flow of wastewater.

[0013] In the above-mentioned device for simultaneous recovery of nitrogen and phosphorus from wastewater by electro-driven struvite crystallization precipitation, the reaction chamber includes a conical bottom, the discharge port is located at the bottom of the conical bottom, and a struvite collection structure is provided below the discharge port.

[0014] The conical bottom of the cavity guides the struvite sediment to the lowest point of the outlet. The struvite collection structure is used to separate the struvite from the mixed liquid discharged from the outlet, thus realizing the recycling and collection of struvite.

[0015] In the above-mentioned device for simultaneous recovery of nitrogen and phosphorus from wastewater by electric-driven struvite crystallization and precipitation, the struvite collection structure includes a filter screen, which is connected below the discharge port. A collection tank is provided below the filter screen. The filter screen includes a filtration and collection chamber, and a switch valve is provided on the discharge port.

[0016] The mixed liquid discharged from the outlet enters the collection tank through a filter screen. The filter screen is concave in shape and densely covered with fine pores. After the mixed liquid passes through the filter screen, the bird droppings sediment is intercepted, realizing bird droppings separation. Moreover, the wastewater in the collection tank can be recycled or transported to downstream treatment devices.

[0017] In the above-mentioned device for simultaneous recovery of nitrogen and phosphorus from wastewater by electro-driven struvite crystallization and precipitation, at least two filter screens are provided, located at the receiving position below the discharge port and the pouring position to the side of the receiving position, respectively. A collection frame is provided below the pouring position. The side of the filter screen is rotatably connected to the rotating platform on which the mounting vertical rod is installed via a side rod, and the rotating platform is rotatably connected to the mounting vertical rod. The rotating table is connected to the shifting driver, which can control the movement of each filter screen between the receiving position and the pouring position; the side rod is connected to the tilting driver, which can control the filter screen on the pouring position to tilt so as to pour the filter residue in the filter collection chamber into the collection frame.

[0018] Multiple filter screens are provided. One screen, located below the discharge port, receives the liquid and traps the struvite. Another screen waits at the discharge position on one side. After accumulating a significant amount of sediment, the screen at the receiving position rotates to the discharge position, emptying the filter residue into the collection frame. The screen at the original discharge position then rotates to the receiving position, automating struvite collection. The screen may be partially or entirely rigid to ensure that the filter collection chamber can be inverted during rotation to empty the internal filter residue. For example, it could be a cylindrical rigid body with a mesh bottom. Both the shifting and tilting actuators can be powered by motors, which is common knowledge.

[0019] In the above-mentioned electrically driven struvite crystallization and precipitation device for simultaneous recovery of nitrogen and phosphorus from wastewater, a reflux structure is provided between the discharge port and the inlet port. The reflux structure includes a reflux pipe, with its two ends connected to the collection tank and the inlet port, respectively. A power pump is connected to the reflux pipe.

[0020] The reflux structure is used to return the wastewater in the collection tank to the reaction chamber to ensure nitrogen and phosphorus removal rates.

[0021] In the above-mentioned device for simultaneous recovery of nitrogen and phosphorus from wastewater by electro-driven struvite crystallization and precipitation, the reaction chamber is equipped with one or more of the following: pH sensor, ammonia nitrogen sensor, temperature sensor, and water level sensor. The top of the reaction chamber is detachably sealed by a top cover, which is equipped with a gas recovery structure.

[0022] The gas recovery structure is used to collect hydrogen, oxygen and other gases produced in the reaction to prevent indiscriminate discharge. The sensors in the reaction chamber are used to detect the state of the wastewater to ensure that the treatment is carried out smoothly and safely.

[0023] In the aforementioned electrically driven struvite crystallization and sedimentation device for simultaneous recovery of nitrogen and phosphorus from wastewater, the inlet of the reaction chamber is connected to a pretreatment unit. The pretreatment unit includes a sedimentation tank with a filter screen at its upper part and a pretreatment outlet in its middle, which is connected to the inlet. Furthermore, a pH adjustment tank is provided between the pretreatment outlet and the inlet, and this pH adjustment tank contains a pH sensor and a pH adjustment assembly.

[0024] The pretreatment unit is used for the initial treatment of wastewater, mainly removing fixed impurities from the wastewater through filtration and sedimentation. The pH adjustment tank is used to roughly adjust the pH of the wastewater to ensure the smooth start-up and operation of subsequent electrochemical reactions.

[0025] Compared with the prior art, the present invention has the following main advantages: 1. The generation rate of magnesium ions can be precisely controlled by the current magnitude to match different nitrogen and phosphorus concentrations in wastewater, avoiding waste or deficiency. Magnesium ions are generated from soluble anodes, eliminating the need for additional magnesium-containing chemicals, reducing operating costs and the risk of secondary pollution, making it suitable for rural areas with limited operation and maintenance capabilities.

[0026] 2. The positive and negative terminals can be reversed in polarity, allowing the soluble anode to connect to the negative terminal to become the cathode, and the inert cathode to connect to the anode to become the anode. At this point, a reduction reaction occurs at the soluble anode, where water is electrocatalyzed to produce hydrogen and hydroxide ions. The hydroxide ions chemically react with the passivation film on the surface, dissolving or destroying it. The hydrogen bubbles also physically scour and peel away the passivation film, effectively removing the passivation layer. Meanwhile, an oxidation reaction occurs at the inert cathode, and the resulting oxygen bubbles also help remove deposits such as struvite adhering to the inert cathode.

[0027] 3. Multiple filter screens are provided. One screen is located below the liquid outlet to receive the liquid discharged from the outlet and trap the struvite. Another screen waits at the discharge position on one side. After the filter screen at the receiving position has collected a large amount of sediment, it rotates to the discharge position to pour the filter residue into the collection box. The filter screen at the original discharge position then rotates to the receiving position, thus automating the collection of struvite. Attached Figure Description

[0028] Figure 1 This is an overall schematic diagram provided by this utility model; Figure 2 This is a vertical cross-sectional schematic diagram of the reactor section provided by this utility model; Figure 3 This is a cross-sectional schematic diagram of the reactor section provided by this utility model; Figure 4 This is a schematic diagram of the bird droppings collection structure provided by this utility model.

[0029] In the diagram, reactor 1, reaction chamber 2, soluble anode 3, inert cathode 4, stirring structure 5, stirring blade 6, conical cavity bottom 7, liquid outlet 8, struvite collection structure 9, filter screen 10, collection tank 11, filter collection chamber 12, top cover 13, switch valve 14, material receiving position 15, material pouring position 16, collection frame 17, side rod 18, mounting vertical rod 19, rotating table 20, liquid inlet 22, reflux structure 23, reflux pipe 24, pretreatment unit 25, sedimentation tank 26, filter grid 27, pretreatment outlet 28. Detailed Implementation

[0030] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0031] Specific implementation examples Figures 1-4 As shown, this electrically driven struvite crystallization and precipitation device for simultaneous recovery of nitrogen and phosphorus from wastewater includes a reactor 1, within which a reaction chamber 2 is formed. The reaction chamber 2 contains two pairs of soluble anodes 3 and inert cathodes 4 arranged in a concentric cylindrical alternating pattern. The soluble anodes 3 are made of magnesium, and the inert cathodes 4 are made of stainless steel. The soluble anodes 3 are connected to the positive terminal of a DC power supply with reverse polarity, and the inert cathodes 4 are connected to the negative terminal of the DC power supply with reverse polarity. The positive and negative terminals can simultaneously reverse their polarities.

[0032] Specifically, reactor 1 provides the reaction site, with a soluble anode 3 and an inert cathode 4 installed in its reaction chamber 2. Driven by electricity, the soluble anode 3 undergoes an oxidation reaction, where magnesium loses electrons to generate magnesium ions. Magnesium ions, ammonium ions, and phosphate ions combine to form MgNH4PO4·6H2O, i.e., struvite, thus achieving the recovery of nitrogen and phosphorus from wastewater. At the cathode, a hydrogen evolution reaction occurs, where water is electrolyzed to generate hydrogen gas and hydroxide ions. The hydroxide ions increase the pH value of the solution, and the alkaline environment promotes the formation of struvite crystals. Moreover, the reaction is driven by electricity, meaning that the rate of magnesium ion generation can be precisely controlled by the current to match different nitrogen and phosphorus concentrations in the wastewater, avoiding waste or insufficiency. Magnesium ions are generated from the soluble anode 3, eliminating the need for additional magnesium-containing chemicals, reducing operating costs and the risk of secondary pollution, making it particularly suitable for rural areas with limited operational and maintenance capabilities.

[0033] Furthermore, during normal reaction, the soluble anode 3 is connected to the positive electrode, and the inert cathode 4 is connected to the negative electrode. However, as the reaction proceeds, magnesium does not completely and uniformly dissolve on the anode surface. Simultaneously, dissolved oxygen or other oxidizing substances in the wastewater partially oxidize the anode surface, forming a dense passivation film of magnesium oxide or magnesium hydroxide. This film is non-conductive and encapsulates the anode, leading to a sharp increase in electrode resistance, requiring a higher voltage to maintain the current, resulting in increased energy consumption. Furthermore, the release of magnesium ions is hindered, reducing the efficiency of struvite formation, and in severe cases, potentially causing system failure and complete cessation of the reaction. Therefore, the positive and negative terminals of this device can be reversed, connecting the soluble anode 3 to the negative electrode to become the cathode, and the inert cathode 4 to the anode to become the anode. At this point, a reduction reaction occurs at the soluble anode 3, where water produces hydrogen and hydroxide ions under electrocatalysis. The hydroxide ions chemically react with the passivation film on the surface, dissolving or destroying it. The hydrogen bubbles physically scour and peel off the passivation film, effectively removing the passivation layer. The inert cathode 4 undergoes an oxidation reaction, which may cause slight corrosion to the motor, but this state is generally short-lived. The inert cathode 4 is made of corrosion-resistant material, so the corrosion effect is within a controllable range. The oxygen bubbles generated by the oxidation reaction also help to remove deposits such as bird droppings attached to the inert cathode 4.

[0034] In this embodiment, a stirring structure 5 is provided in the reaction chamber 2 to promote the contact between sewage and soluble anode 3 and inert cathode 4. The stirring structure 5 includes stirring blades 6, which are connected to a stirring driver (not specifically shown in the figure) via a stirring shaft. The stirring structure 5 is disposed between the circularly arranged soluble anode 3 and inert cathode 4. The soluble anode 3 and inert cathode 4 are arc-shaped and curved along the stirring direction.

[0035] like Figure 1 , 2As shown, the reaction chamber 2 includes a conical bottom 7, with a discharge port 8 located at the bottom of the conical bottom 7. Below the discharge port 8 is a struvite collection structure 9. The struvite collection structure 9 includes a filter screen 10, which is located below the discharge port 8. Below the filter screen 10 is a collection tank 11. The filter screen 10 includes a filtration and collection chamber 12. A switch valve 14 is installed on the discharge port 8. A reflux structure 23 is provided between the discharge port 8 and the inlet 22. The reflux structure 23 includes a reflux pipe 24, with both ends connected to the collection tank 11 and the inlet 22, respectively. A power pump (not specifically shown in the figure) is connected to the reflux pipe 24. Two filter screens 10 are provided, located at the receiving position 15 below the liquid outlet 8 and the pouring position 16 to the side of the receiving position 15, respectively. A collection frame 17 is provided below the pouring position 16. The side of the filter screen 10 is rotatably connected to the rotating table 20 with the mounting vertical rod 19 via the side rod 18. The rotating table 20 is rotatably connected to the mounting vertical rod 19. The rotating table 20 is connected to the position driver (not specifically shown in the figure) and can control the movement of each filter screen 10 between the receiving position 15 and the pouring position 16. The side rod 18 is connected to the flipping driver (not specifically shown in the figure) and can control the filter screen 10 on the pouring position 16 to flip so that the filter residue in the filter collection chamber 12 can be poured into the collection frame 17.

[0036] Specifically, the conical bottom 7 guides the struvite sediment to the lowest point of the discharge port 8. The struvite collection structure 9 separates the struvite from the mixed liquid discharged from the discharge port 8, achieving struvite recycling. The mixed liquid discharged from the discharge port 8 enters the collection tank 11 through the filter screen 10. The filter screen 10 is concave and densely covered with fine pores. After passing through the filter screen 10, the struvite sediment is trapped, achieving struvite separation. Moreover, the wastewater in the collection tank 11 can be recycled or transported to downstream treatment devices. Multiple filter screens 10 are provided. One is located below the discharge port 8 to receive the liquid discharged from the discharge port 8 and trap struvite. Another waits at the discharge position 16 on one side. After receiving a large amount of sediment, the filter screen 10 at the receiving position 15 rotates to the discharge position 16, pouring the filter residue into the collection frame 17. The filter screen 10 at the original discharge position 16 rotates to the receiving position 15, realizing automated struvite collection.

[0037] In this embodiment, the reaction chamber 2 is equipped with a pH sensor, an ammonia nitrogen sensor, a temperature sensor, and a water level sensor; the top of the reaction chamber 2 is detachably sealed by a top cover 13, and the top cover 13 is equipped with a gas recovery structure.

[0038] As an optimization of this embodiment, the inlet 22 of the reaction chamber 2 is connected to the pretreatment unit 25. The pretreatment unit 25 includes a sedimentation tank 26, with a filter grid 27 on the upper part of the sedimentation tank 26 and a pretreatment outlet 28 in the middle of the sedimentation tank 26, which is connected to the inlet 22. The pretreatment unit 25 is used for the preliminary treatment of wastewater, mainly removing fixed impurities from the wastewater through filtration and sedimentation.

[0039] The specific working principle is as follows: the wastewater to be treated is fed into the sedimentation tank 26, the filter screen 27 filters out the larger solids in the wastewater, the wastewater settles at the bottom of the tank for a period of time, and the supernatant is output from the pretreatment outlet 28 and fed into the reactor 1 from the inlet 22.

[0040] Inside reaction chamber 2, the soluble anode 3 undergoes an oxidation reaction, where magnesium loses electrons to form magnesium ions. These magnesium ions, ammonium ions, and phosphate ions combine to form MgNH4PO4·6H2O, i.e., struvite precipitate. Meanwhile, the inert cathode 4 undergoes a hydrogen evolution reaction, generating hydrogen gas and hydroxide ions. The hydroxide ions increase the pH of the solution.

[0041] As the reaction proceeds, after a preset time, the positive and negative terminals of the polarity-reversed DC power supply are reversed, connecting the soluble anode 3 to the negative terminal to become the cathode, and the inert cathode 4 to the anode to become the anode. At this time, a reduction reaction occurs at the soluble anode 3, where water is electrocatalyzed to produce hydrogen and hydroxide ions. The hydroxide ions react chemically with the passivation film on the surface, dissolving or destroying it. The hydrogen bubbles physically scour and peel off the passivation film, effectively removing the passivation layer. Meanwhile, an oxidation reaction occurs at the inert cathode 4, and the generated oxygen bubbles also help remove precipitates such as struvite adhering to the inert cathode 4. After a short period of time, the reversed state is restored, and the "cleaned" soluble anode 3 is reconnected to the positive terminal.

[0042] The specific embodiments described herein are merely illustrative examples illustrating the spirit of this utility model. Those skilled in the art to which this utility model pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of this utility model or exceeding the scope defined by the appended claims.

Claims

1. A device for simultaneously recovering nitrogen and phosphorus from wastewater by electro-driven struvite crystallization and precipitation, comprising a reactor (1), wherein a reaction chamber (2) is formed within the reactor (1), characterized in that, The reaction chamber (2) is provided with N pairs of soluble anodes (3) and inert cathodes (4), where N≥1. The soluble anodes (3) are connected to the positive terminal of the polarity reversal DC power supply, and the inert cathodes (4) are connected to the negative terminal of the polarity reversal DC power supply. The positive and negative terminals can simultaneously reverse polarity.

2. The device for simultaneous recovery of nitrogen and phosphorus from wastewater by electro-driven struvite crystallization and precipitation according to claim 1, characterized in that, The soluble anode (3) comprises magnesium and / or magnesium alloys, and the inert cathode (4) comprises stainless steel.

3. The device for simultaneous recovery of nitrogen and phosphorus from wastewater by electro-driven struvite crystallization and precipitation according to claim 1, characterized in that, The N≥2, the soluble anode (3) and the inert cathode (4) are both plate-shaped; the soluble anode (3) and the inert cathode (4) are arranged in alternating layers of parallel plates or in alternating concentric cylindrical arrangements.

4. The device for simultaneous recovery of nitrogen and phosphorus from wastewater by electro-driven struvite crystallization and precipitation according to claim 3, characterized in that, The reaction chamber (2) is provided with a stirring structure (5), which includes a stirring blade (6), and the stirring blade (6) is connected to the stirring driver through a stirring shaft; The stirring structure (5) is disposed between the circularly arranged soluble anode (3) and inert cathode (4), and the soluble anode (3) and inert cathode (4) are arc-shaped and bent along the stirring direction; Alternatively, the stirring structure (5) is disposed below the soluble anode (3) and inert cathode (4) which are distributed in a parallel plate manner, and the soluble anode (3) and inert cathode (4) are in the shape of planar plates.

5. The device for simultaneous recovery of nitrogen and phosphorus from wastewater by electro-driven struvite crystallization and precipitation according to claim 1, characterized in that, The reaction chamber (2) includes a conical bottom (7), the bottom of which is provided with a liquid outlet (8), and a bird droppings collection structure (9) is provided below the liquid outlet (8).

6. The device for simultaneous recovery of nitrogen and phosphorus from wastewater by electro-driven struvite crystallization and precipitation according to claim 5, characterized in that, The guano collection structure (9) includes a filter screen (10), which is located below the liquid outlet (8). A liquid collection tank (11) is provided below the filter screen (10). The filter screen (10) includes a filtration collection chamber (12). A switch valve (14) is provided on the liquid outlet (8).

7. The device for simultaneous recovery of nitrogen and phosphorus from wastewater by electro-driven struvite crystallization and precipitation according to claim 6, characterized in that, The filter screen (10) is provided in at least two locations, namely the receiving position (15) below the liquid outlet (8) and the pouring position (16) to the side of the receiving position (15). A collection frame (17) is provided below the pouring position (16). The side of the filter screen (10) is rotatably connected to the rotating platform (20) on which the mounting vertical rod (19) is installed via a side rod (18), and the rotating platform (20) is rotatably connected to the mounting vertical rod (19); The rotating table (20) is connected to the shifting driver and can control each filter screen (10) to move between the receiving position (15) and the pouring position (16); the side rod (18) is connected to the flipping driver and can control the filter screen (10) on the pouring position (16) to flip so that the filter residue in the filter collection chamber (12) can be poured into the collection frame (17).

8. The device for simultaneous recovery of nitrogen and phosphorus from wastewater by electro-driven struvite crystallization and precipitation according to claim 6, characterized in that, A reflux structure (23) is provided between the liquid outlet (8) and the liquid inlet (22) of the reactor (1). The reflux structure (23) includes a reflux pipe (24). The two ends of the reflux pipe (24) are connected to the liquid collection tank (11) and the liquid inlet (22) respectively. A power pump is connected to the reflux pipe (24).

9. The apparatus for simultaneous recovery of nitrogen and phosphorus from wastewater by electro-driven struvite crystallization and precipitation according to any one of claims 1-8, characterized in that, The reaction chamber (2) is equipped with one or more of the following: pH sensor, ammonia nitrogen sensor, temperature sensor and water level sensor; the top of the reaction chamber (2) is detachably sealed by a top cover (13), and the top cover (13) is equipped with a gas recovery structure.

10. The apparatus for simultaneous recovery of nitrogen and phosphorus from wastewater by electrically driven struvite crystallization and precipitation according to any one of claims 1-8, characterized in that, The inlet (22) of the reaction chamber (2) is connected to the pretreatment unit (25). The pretreatment unit (25) includes a sedimentation tank (26). The sedimentation tank (26) is equipped with a filter grid (27) at the top and a pretreatment outlet (28) in the middle. The pretreatment outlet (28) is connected to the inlet (22).

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