A device for recovering nitrogen and phosphorus for sewage treatment

Abstract

The utility model provides a kind of nitrogen phosphorus recovery device for sewage treatment, comprising: air flotation system, the sewage to be treated enters to air flotation system, the air flotation system is used to form air flotation process, remove residue in sewage;First pH adjusting pool, the sewage after the air flotation system enters the first pH adjusting pool, the first pH adjusting pool is used to adjust sewage to preset pH value.The utility model is by air flotation system and first pH adjusting pool after sewage treatment, in coagulation tank, MgCl2 is added, sewage will occur as follows Reaction Mg 2+ +NH 4+ +PO4 3‑ +6H2O→MgNH4PO4·6H2O↓, so that the struvite "ammonium magnesium phosphate crystal" is generated, then through crystallization pool, sedimentation tank is handled, struvite is separated from sewage, and the struvite separated from sedimentation tank is discharged, to achieve the purpose of recycling struvite.

Description

Technical Field

[0001] This utility model relates to the technical field of wastewater treatment, and in particular to a nitrogen and phosphorus recovery device for wastewater treatment. Background Technology

[0002] Large-scale farms produce wastewater containing large amounts of COD, nitrogen, phosphorus, organic matter, and pathogens, resulting from excessive feed input, stagnant residue, and wastewater from cleaning the feeding area mixed with livestock and poultry manure and urine. This wastewater is difficult to store and treat, and since the surrounding farmland is insufficient to absorb it, transporting it to distant lands would require addressing transportation and secondary pollution issues.

[0003] Aquaculture wastewater contains high concentrations of nitrogen and phosphorus, and traditional treatment methods cannot recover nitrogen and phosphorus, which is a waste of resources. Utility Model Content

[0004] Therefore, the purpose of this utility model is to provide a nitrogen and phosphorus recovery device for wastewater treatment.

[0005] This utility model provides the following technical solution: a nitrogen and phosphorus recovery device for wastewater treatment, comprising:

[0006] The air flotation system is used to remove residues from the wastewater by forming an air flotation process.

[0007] The first pH adjustment tank is used to adjust the wastewater to a preset pH value after passing through the air flotation system.

[0008] Wastewater that has passed through the first pH adjustment tank enters the coagulation tank. Reactive materials are added to the coagulation tank, which is used to fully mix the wastewater and the reactive materials.

[0009] The wastewater that has passed through the coagulation tank enters the crystallization tank, which is used to crystallize the wastewater.

[0010] The sedimentation tank is used to separate the crystals from the wastewater after passing through the crystallization tank.

[0011] The second pH adjustment tank is where the wastewater that has passed through the sedimentation tank enters. The second pH adjustment tank is used to adjust the pH value of the wastewater.

[0012] Furthermore, the air flotation system includes: a reaction tank, a transition tank, a contact tank, an air flotation tank, and a dissolved air assembly;

[0013] The wastewater to be treated enters the reaction tank, which is used to cause the fine suspended solids and colloidal particles in the wastewater to undergo a flocculation reaction, forming large-diameter flocs that can be adsorbed by bubbles.

[0014] The transition pool is provided between the reaction pool and the contact pool; the transition pool is used to avoid the turbulence in the reaction pool from impacting the subsequent microbubble and floc bonding process in the contact pool.

[0015] The contact pool is used to allow the microbubbles to come into full contact with and adhere to the flocs, forming a "bubble-floc" composite.

[0016] The flotation tank is used to achieve solid-liquid separation, causing the composite to float to the water surface and form scum;

[0017] The dissolved air component is used to provide the microbubbles in the air flotation system;

[0018] Furthermore, the air flotation system also includes: a slag scraper and a slag skimming tank;

[0019] The scum scraper is installed on the flotation tank, and the scum skimming trough is installed on the side of the flotation tank. The scum scraper is used to scrape the scum in the flotation tank into the scum skimming trough.

[0020] Furthermore, the recycling device also includes a stirrer installed on the crystallization tank and a guide tube installed inside the crystallization tank;

[0021] The guide tube is open at both ends, and there is a gap between the bottom of the guide tube and the bottom wall of the crystallization tank. The stirring blades of the agitator are located inside the guide tube. By starting the agitator, positive and negative pressures are formed on the upper and lower sides of the guide tube, thereby causing the wastewater in the crystallization tank to circulate up and down.

[0022] Furthermore, the recycling device also includes a sludge hopper at the bottom of the sedimentation tank and a sludge scraper on the sedimentation tank, the sludge scraper being used to scrape the sludge in the sedimentation tank toward the sludge hopper.

[0023] Furthermore, the recycling device also includes a reflux assembly for returning a portion of the sludge in the sludge hopper to the crystallization tank.

[0024] Furthermore, the reflux assembly includes a second reflux pipe, a sludge reflux pump, and a first reflux pipe;

[0025] The inlet of the sludge return pump is connected to one end of the second return pipe, and the other end of the second return pipe is connected to the sludge hopper.

[0026] The output port of the sludge return pump is connected to one end of the first return pipe, and the other end of the first return pipe is connected to the crystallization tank.

[0027] Furthermore, the recycling device also includes a cleaning assembly for cleaning the sludge scraper.

[0028] Furthermore, the sedimentation tank is an inclined tube or inclined plate sedimentation tank.

[0029] Furthermore, a mixer is installed on each of the reaction tank, the first pH adjustment tank, the coagulation tank, and the second pH adjustment tank.

[0030] The beneficial effects of this invention are: after treating wastewater through an air flotation system and a first pH adjustment tank, adding MgCl2 to the coagulation tank will cause the wastewater to undergo the following reaction: Mg 2+ +NH 4+ +PO4 3- +6H2O→MgNH4PO4·6H2O↓, thus generating struvite "magnesium ammonium phosphate crystals". After being treated in a crystallization tank and a sedimentation tank, the struvite is separated from the wastewater. The separated struvite is discharged from the sedimentation tank to achieve the purpose of struvite recycling. The wastewater is discharged after the pH value is adjusted by a second pH adjustment tank to avoid pollution. Attached Figure Description

[0031] Figure 1 This is a structural diagram of each component of the present invention.

[0032] Figure 2 This is a three-dimensional structural diagram of the dissolved gas component of this utility model.

[0033] Figure 3 This is a three-dimensional structural diagram of the reflux assembly and the cleaning assembly of this utility model.

[0034] Figure 4 This is a plan view of the present utility model.

[0035] The labels in the attached diagram are as follows: 1-Reaction tank, 2-Transition tank, 3-Contact tank, 4-Agitator, 5-Scraper, 51-Skimming trough, 6-Air flotation tank, 7-Dissolved air assembly, 71-Dissolved air pump, 72-Dissolved air tank, 73-First connecting pipe, 74-Second connecting pipe, 75-Air compressor, 76-Third connecting pipe, 77-Fourth connecting pipe, 8-Effluent tank, 9-First pH adjustment tank, 10-Coagulation tank, 11-First pH meter, 12-Crystallization tank, 13-Guide cylinder, 14-Plug flow zone, 15-Sedimentation tank, 151 - Effluent tank, 16- Sludge scraper, 17- Sludge hopper, 18- Return flow assembly, 181- First return pipe, 182- Flow meter, 183- Second return pipe, 184- Sludge return pump, 19- Cleaning assembly, 191- Medium water tank, 192- Acid chemical tank, 193- Agitator, 194- Level gauge, 195- Clean water pump, 196- Cleaning pipe, 197- Input pipe, 198- Acid-resistant pump, 199- First dosing pipe, 1910- Second dosing pipe, 20- Second pH adjustment tank, 21- Second pH meter. Detailed Implementation

[0036] To facilitate understanding of this utility model, a more complete description will be given below with reference to the accompanying drawings. Several embodiments of this utility model are shown in the drawings. However, this utility model can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this utility model will be more thorough and complete.

[0037] It should be noted that when a component is said to be "fixed to" another component, it can be directly on the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0039] This embodiment provides a nitrogen and phosphorus recovery device for wastewater treatment, such as... Figure 1 and Figure 4The system includes: an air flotation system, a first pH adjustment tank 9, a coagulation tank 10, a crystallization tank 12, a sedimentation tank 15, and a second pH adjustment tank 20; livestock and poultry breeding wastewater passes through the above tanks in sequence to complete the nitrogen and phosphorus recovery operation.

[0040] The wastewater to be treated enters the air flotation system, which is used to form an air flotation process to remove residues from the wastewater, such as feed residues and feces.

[0041] Specifically, the flotation system includes: reaction tank 1, transition tank 2, contact tank 3, flotation tank 6, and dissolved air assembly 7; the wastewater to be treated flows sequentially through reaction tank 1, transition tank 2, contact tank 3, and flotation tank 6 before flowing into the first pH adjustment tank 9.

[0042] The function of reaction tank 1 is to cause fine suspended solids and colloidal particles in wastewater to undergo flocculation reaction by adding flocculants such as PAM and PAC, forming large-diameter flocs that can be adsorbed by air bubbles; a mixer 4 is installed on reaction tank 1 to fully mix the flocculant with the wastewater.

[0043] A transition tank 2 is provided between the reaction tank 1 and the contact tank 3. The function of the transition tank 2 is to buffer the water flow, stabilize the water quality, and prevent the turbulent flow in the reaction tank 1 from impacting the bubble-floc bonding process in the subsequent contact tank 3.

[0044] The function of contact tank 3 is to allow microbubbles to fully contact and adhere to the flocculated flocs, forming a "bubble-floc" composite with a density less than water, thus laying the foundation for subsequent flotation and separation.

[0045] The function of the flotation tank 6 "separation tank" is to achieve solid-liquid separation - the "bubble-floc" complex with attached bubbles floats to the water surface to form scum, and the clear water is discharged from the bottom of the tank;

[0046] like Figure 2 As shown, dissolved air component 7 is used to provide microbubbles in the air flotation system;

[0047] Specifically, the dissolved gas assembly 7 includes a dissolved gas pump 71, a dissolved gas tank 72, a first connecting pipe 73, a second connecting pipe 74, an air compressor 75, a third connecting pipe 76, and a fourth connecting pipe 77.

[0048] The inlet of the dissolved air pump 71 is fixedly connected to one end of the second connecting pipe 74, the outlet of the dissolved air pump 71 is fixedly connected to one end of the first connecting pipe 73, the other end of the first connecting pipe 73 is fixedly connected to the dissolved air tank 72, one end of the fourth connecting pipe 77 is fixedly connected to the dissolved air tank 72, and the other end is fixedly connected to the air compressor 75. One end of the third connecting pipe 76 is connected to the transition tank 2, and the other end is connected to the dissolved air tank 72.

[0049] Among them, the air compressor 75 provides the air source for the bubbles. Its core function is to provide compressed air "source" for the dissolved air component 7 and is the "raw material supply device" for microbubbles. It can be understood that by starting the air compressor 75, compressed air is introduced into the dissolved air tank 72 through the fourth connecting pipe 77.

[0050] Dissolved air pump 71: Realizes gas-liquid mixing and pressurization. Its core function is to forcibly mix the compressed air provided by air compressor 75 with the return clean water "or the effluent from flotation tank 6" and pressurize and deliver it to dissolved air tank 72. It is the "power device for gas-liquid dissolution". It can be understood that by starting dissolved air pump 71, the wastewater to be treated or the clean water after passing through flotation tank 6 is input into dissolved air tank 72 through second connecting pipe 74 and first connecting pipe 73. In this embodiment, an effluent tank 8 is set between flotation tank 6 and first pH adjustment tank 9. The wastewater after being treated by flotation tank 6 enters effluent tank 8. The other end of second connecting pipe 74 is connected to effluent tank 8, thereby starting dissolved air pump 71 to input the wastewater in effluent tank 8 into dissolved air tank 72.

[0051] Dissolved gas tank 72: The "reaction vessel" for air dissolution. Its core function is to allow the gas-liquid mixture to come into full contact under pressure, so that the air can be efficiently dissolved in the water to form dissolved air water, which is "water containing dissolved air". It is the "key place for air dissolution". It can be understood that the dissolved air water treated by dissolved gas tank 72 is transported to the transition tank 2 through the third connecting pipe 76.

[0052] The working process of dissolved gas component 7 can be referenced as follows:

[0053] 1. Air compressor 75 compresses air to 0.4MPa and delivers it to dissolved air pump 71 as an air source;

[0054] 2. The dissolved air pump 71 mixes compressed air with the return clean water "or the effluent from the flotation tank 6", pressurizes it to 0.4MPa, and then sends it into the dissolved air tank 72;

[0055] 3. Inside the dissolved air tank 72, air is fully dissolved in water under pressure and baffles to form dissolved air water;

[0056] 4. The dissolved air water is depressurized by the release device, releasing a large number of microbubbles, which combine with the flocs "such as fecal particles flocculated by PAM" in the flotation tank 6, float to the surface to form scum, and complete the separation of SS "suspended solids".

[0057] Furthermore, the flotation system also includes: a slag scraper 5 and a slag skimming trough 51;

[0058] The scum scraper 5 is installed on the flotation tank 6, and the scum skimming trough 51 is installed on the side of the flotation tank 6. The scum scraper 5 is used to scrape the scum in the flotation tank 6 into the scum skimming trough 51.

[0059] Specifically, the mechanism of the sludge scraper 5 is existing technology, and the entire dissolved air flotation system is also existing technology, which can be found in technical manuals in this field. In addition, it is widely used in the field of wastewater treatment. The following is a description of the operation of the sludge scraper 5:

[0060] In the flotation tank 6, suspended matter attached by microbubbles, such as fecal particles, feed residues, colloidal flocs, etc. in aquaculture wastewater, will form a scum layer with a density less than water, typically 5-10 cm thick and with a water content of 95%-98%, which floats on the water surface.

[0061] The function of the scum scraper 5 is to use a mechanical scraper to scrape the scum from the water surface to the skimming trough 51 at the edge of the tank, and finally discharge it from the system, preventing the scum from remaining or sinking back into the water and affecting the quality of the effluent. The scum scraper 5 is based on the principle of mechanical scraping and gravity guidance. The drive device drives the scraper to move periodically along the water surface of the flotation tank 6. The contact pressure between the scraper and the water surface is used to push the scum towards the skimming trough 51 on one side of the tank.

[0062] Working process of slag scraper 5:

[0063] Scum formation stage:

[0064] After the aquaculture wastewater undergoes coagulation reaction with the addition of PAM and gas-liquid contact, suspended particles combine with microbubbles to form scum, which accumulates in the "floating zone" of the flotation tank 6 and gradually forms a stable scum layer with a thickness of about 8cm. At this time, the scum scraper 5 is in standby mode.

[0065] Slag scraping start-up phase:

[0066] When the thickness of the scum layer reaches the set threshold (usually controlled by a liquid level sensor or timer), the scum scraper 5 is started. The motor drives the scraper frame to move horizontally along the length of the pool at a speed of 0.5 to 1 m / min ("horizontal scum scraper 5") or rotate around the central axis ("rotary scum scraper 5").

[0067] The scraper contacts the scum layer and uses its tilt angle to push the scum forward, preventing the scum from being "pressed" into the water by the scraper.

[0068] Scum collection stage:

[0069] The scraper pushes the scum to the skimming trough 51 at the edge of the flotation tank 6 (the trough opening is 5-10mm below the water surface). The scum flows into the trough under gravity and is discharged through the pipeline to the subsequent treatment unit (such as the sludge thickening tank or plate and frame filter press).

[0070] Return reset phase:

[0071] After completing one scum removal cycle, the scraper resets via a reverse motion: "The translational scraper returns to the starting end, and the rotary scraper reverses direction." During the reset process, the scraper can be lifted (in some models), avoiding contact with the water surface or stirring up clean water, thus reducing energy consumption and disturbance to the scum layer.

[0072] Cyclic cycle:

[0073] Repeat the above process according to the set cycle to ensure that the scum on the surface of the flotation tank 6 is removed in time and the effluent residue is maintained at ≤100mg / L, which meets the influent requirements of the subsequent MAP crystallization process.

[0074] Wastewater passing through the flotation system enters the first pH adjustment tank 9, which is used to adjust the wastewater to a preset pH value.

[0075] Specifically, wastewater enters the first pH adjustment tank 9, and the pH is adjusted to 9.0-9.5 by adding NaOH to the first pH adjustment tank 9 so that the subsequent crystallization reaction occurs in an alkaline environment; a stirrer 4 is also installed on the first pH adjustment tank 9 to mix the liquid in the first pH adjustment tank 9; NaOH is added by a dosing pump, and the amount of NaOH added by the dosing pump is automatically adjusted according to the first pH meter 11;

[0076] Wastewater passing through the first pH adjustment tank 9 enters the coagulation tank 10. Reactive materials are added to the coagulation tank 10, which is used to fully mix the wastewater and the reactive materials.

[0077] Specifically, MgCl2 is added to coagulation tank 10 at a molar ratio of Mg:P of 1.3:1 to ensure thorough mixing of MgCl2 with the wastewater in coagulation tank 10, which facilitates subsequent mixing with NH4+ in the wastewater. 4+ +PO4 3- The reaction is fully carried out; a stirrer 193 and a first pH meter 11 are installed on the coagulation tank 10; the stirrer 193 ensures that MgCl2 is fully mixed with the wastewater in the coagulation tank 10; the first pH meter 11 is placed in the coagulation tank 10, which is more advantageous than the first pH adjustment tank 9 because the reaction is delayed when NaOH is added to the first pH adjustment tank 9.

[0078] Wastewater passing through coagulation tank 10 enters crystallization tank 12, which is used to crystallize the wastewater.

[0079] Specifically, crystallization pool 12 functions as the core reaction zone for the crystallization reaction, where the following occurs: Mg 2+ +NH 4+ +PO4 3- +6H2O→MgNH4PO4·6H2O↓;

[0080] Furthermore, the crystallization tank 12 is equipped with a stirrer 4, and a guide tube 13 is installed inside the crystallization tank 12;

[0081] The guide tube 13 is open at both ends and is suspended inside the crystallization tank 12 by a bracket, so that there is a gap between the bottom of the guide tube 13 and the bottom wall of the crystallization tank 12. The stirring blade of the agitator 4 is located in the middle of the inner side of the guide tube 13. When the agitator 4 is started, the stirring blade of the agitator 4 rotates, so that positive and negative pressure are formed on the upper and lower sides of the guide tube 13, thereby causing the wastewater in the crystallization tank 12 to circulate up and down.

[0082] The liquid in crystallization pool 12 is circulated, which can enhance the crystallization efficiency of struvite;

[0083] Specifically, this involves increasing Mg through forced circulation. 2+ NH4 + PO4 3- The probability of ion collisions is increased, the crystallization induction time is shortened, and the nitrogen and phosphorus conversion rate is improved; the flow field is regulated to inhibit the formation of fine crystals, promote crystal growth, and improve the subsequent separation efficiency; it can also uniformly disperse the crystal nuclei returned from the sedimentation tank 15 through the reflux component 18, improve the crystallization efficiency, and reduce magnesium salt consumption; at the same time, it reduces crystal deposition and lowers the risk of scaling in the tank.

[0084] Wastewater and crystals passing through crystallization tank 12 enter sedimentation tank 15, which is used to separate crystals from wastewater.

[0085] Specifically, a flow channel 14 is provided between the crystallization tank 12 and the sedimentation tank 15, and the wastewater from the crystallization tank 12 flows into the sedimentation tank 15 after passing through the flow channel 14; a sludge hopper 17 is provided at the bottom of the sedimentation tank 15, and a sludge scraper 16 is provided on the sedimentation tank 15. The sludge scraper 16 is used to scrape the sludge in the sedimentation tank 15 toward the sludge hopper 17; the sedimentation tank 15 is an inclined tube or inclined plate sedimentation tank 15.

[0086] More specifically, the sedimentation tank 15 is a key unit for achieving "solid-liquid separation". Its core function is to separate the MAP crystals generated in the crystallization tank 12 from the wastewater, while providing crystal nuclei for the crystallization tank 12 for reflux.

[0087] The function of the flow zone 14 is as follows:

[0088] Enhanced particle collision and growth:

[0089] The tiny flocs formed in the flocculation zone continue to collide and combine in the plugging zone, causing the particles to grow further and improving settling performance.

[0090] Because the push flow zone 14 has a certain flow velocity control function, it avoids turbulence from destroying the already formed flocs.

[0091] Improve hydraulic conditions and reduce short-circuiting:

[0092] Traditional sedimentation tank 15 may have short-flow phenomenon, which causes some water to enter the effluent without sufficient sedimentation, reducing the treatment effect;

[0093] The flow zone 14 can evenly distribute the flow velocity, making the flow more stable and avoiding flow interference with the sedimentation process;

[0094] Enhance mud-water separation and improve settling efficiency:

[0095] The buffering effect of the plug flow zone 14 can reduce the upward trend of suspended particles, making them easier to settle, optimizing the mud-water interface, and reducing sludge floating.

[0096] In some cases, sludge floating may affect the quality of the effluent, and the flow control in plug flow zone 14 helps to reduce this risk.

[0097] The sludge scraper 16 is existing technology. The working process of the sludge scraper 16 is described below:

[0098] Sludge deposition stage:

[0099] Suspended particles in wastewater, such as struvite crystals and SS flocs, settle on the inclined plate due to gravity. Some slide to the bottom of the pool, while others adhere to the surface of the inclined plate, gradually forming a sludge layer with a thickness of 5-10 mm.

[0100] Sludge scraper start:

[0101] When the sludge layer thickness reaches the set threshold ("detected by sludge interface instrument") or according to the timed program ("once every 2 to 4 hours"), the sludge scraper 16 starts: the motor drives the chain / guide rail through the reducer, causing the scraper to move along the inclined direction of the inclined plate ("at an angle of 60° to 75° with the horizontal").

[0102] Sludge scraping:

[0103] The scraper, close to the surface of the inclined plate, scrapes off the attached sludge and simultaneously pushes the sludge deposited at the bottom of the tank towards the sludge hopper 17. Due to the inclined design of the plate, the scraped sludge slides down the plate to the main sludge scraping area at the bottom of the tank under the combined action of gravity and the scraper's thrust, and is then collected by the bottom scraper.

[0104] Sludge collection and discharge

[0105] The collected sludge enters the sludge hopper 17, and after short-term concentration (the moisture content is reduced to 90% to 95%), it is discharged through the sludge discharge pipe at the bottom of the hopper (equipped with a valve or screw pump). Part of it is sent to the crystallization tank 12 as crystal nuclei through the reflux assembly 18 at a reflux ratio of 40% to 100%, and the remainder is discharged for recycling.

[0106] Reset standby

[0107] After scraping the mud, the scraper moves in the opposite direction to return to the starting position, waiting for the next operation. The entire process does not affect the normal sedimentation function of the inclined plate.

[0108] Wastewater passing through sedimentation tank 15 enters the second pH adjustment tank 20, which is used to adjust the pH value of the wastewater.

[0109] Specifically, the sedimentation tank 15 is equipped with an outlet trough 151. The wastewater in the sedimentation tank 15 enters the second pH adjustment tank 20 through the outlet trough 151. The second pH adjustment tank 20 is equipped with a mixer 4 and a second pH meter 21. By adding H2SO4 to the second pH adjustment tank 20, the pH of the wastewater is adjusted back to 7 before being discharged. The mixer 4 ensures that the H2SO4 is fully mixed with the water in the second pH adjustment tank 20. The second pH meter 21 is used to check the pH value of the wastewater in the second pH adjustment tank 20 and add an appropriate amount of H2SO4 according to the value.

[0110] Furthermore, the recycling device in this embodiment also includes a reflux assembly 18, which is used to return a portion of the sludge in the sludge hopper 17 to the crystallization tank 12.

[0111] like Figure 3 As shown, the reflux assembly 18 includes a second reflux pipe 183, a sludge reflux pump 184, and a first reflux pipe 181; the inlet of the sludge reflux pump 184 is connected to one end of the second reflux pipe 183, and the other end of the second reflux pipe 183 is connected to the sludge hopper 17; the outlet of the sludge reflux pump 184 is connected to one end of the first reflux pipe 181, and the other end of the first reflux pipe 181 is connected to the crystallization tank 12.

[0112] Specifically, by starting the sludge return pump 184, a portion of the sludge in the sludge hopper 17 is used as crystal nuclei and fed into the crystallization tank 12 through the second return pipe 183 and the first return pipe 181.

[0113] Furthermore, the inner walls of each tank of the nitrogen and phosphorus recovery device and the stirring blades of each mixer 4 are coated with an anti-corrosion coating.

[0114] In summary, after wastewater is treated by the flotation system and the first pH adjustment tank 9, the addition of MgCl2 to the coagulation tank 10 will cause the wastewater to undergo the following reaction: Mg 2+ +NH 4+ +PO4 3- +6H2O→MgNH4PO4·6H2O↓, thus generating struvite "magnesium ammonium phosphate crystals". After being treated by crystallization tank 12 and sedimentation tank 15, the struvite is separated from the sewage. The separated struvite is discharged from sedimentation tank 15 to achieve the purpose of struvite recovery. The sewage is discharged after the pH value is adjusted by the second pH adjustment tank 20 to avoid pollution.

[0115] Furthermore, such as Figure 3 As shown, the recycling device also includes a cleaning assembly 19 for cleaning the sludge scraper 16 and the sedimentation tank 15.

[0116] Specifically, the cleaning assembly 19 includes a medium water tank 191, an acid tank 192, a stirrer 193, a level gauge 194, a clean water pump 195, a cleaning pipe 196, an input pipe 197, an acid-resistant pump 198, a first dosing pipe 199, and a second dosing pipe 1910.

[0117] The inlet of the acid-resistant pump 198 is fixedly connected to the acid tank 192 via the first dosing pipe 199, and the outlet of the acid-resistant pump 198 is fixedly connected to one end of the second dosing pipe 1910. The other end of the second dosing pipe 1910 is fixedly connected to the cleaning pipe 196. The inlet of the clean water pump 195 is connected to the medium water tank 191 via the inlet pipe 197, and the outlet of the clean water pump 195 is connected to one end of the cleaning pipe 196. The other end of the cleaning pipe 196 is connected to a nozzle. Both the medium water tank 191 and the acid tank 192 are equipped with level gauges 194 to display the liquid levels of the medium water tank 191 and the acid tank 192. An agitator 193 is installed on the acid tank 192 to stir and mix the liquid in the acid tank 192.

[0118] Cleaning process of cleaning component 19:

[0119] "Pre-treatment with clean water backwash to remove loose deposits":

[0120] Triggering conditions: Automatically starts every 8 to 12 hours, or manually starts when the pressure difference before and after the inclined tube / plate in sedimentation tank 15 is >2 kPa.

[0121] Operating steps:

[0122] 1. Close the inlet valve of inclined tube sedimentation tank 15, keep the outlet valve open, and drain part of the supernatant in the tank until the liquid level drops to 10cm below the top of the inclined tube / plate.

[0123] 2. Start the clean water pump 195. The clean water in the medium water tank 191 passes through the input pipe 197, the clean water pump 195, and the cleaning pipe 196, and then sprays out through the nozzle. The nozzle is a rotating nozzle. The clean water is sprayed onto the surface of the inclined tube / plate through the rotating nozzle. The flow rate is 10 to 15 L / min per square meter of inclined plate. The nozzle rotates 180° to ensure full coverage.

[0124] 3. Rinse for 5-10 minutes. Loose scum and unsolidified crystal particles will enter the bottom sludge hopper 17 with the water flow, and some will be discharged into the subsequent treatment unit with the supernatant.

[0125] Acid backflushing provides "deep treatment to dissolve hard scale":

[0126] Triggering conditions: Every 24 to 48 hours, or when the pressure difference still exceeds the standard after backflushing with clean water, it should be carried out in conjunction with backflushing with clean water.

[0127] Operating steps:

[0128] 1. After the backwashing with clean water is completed, close the outlet valve and keep the liquid level in the pool at a low level, "submerging the bottom of the inclined tube / plate by 5cm".

[0129] 2. Start the acid-resistant pump 198. The liquid in the acid tank 192 flows from the first dosing pipe 199, the acid-resistant pump 198, and the second dosing pipe 1910 to the cleaning pipe 196, and finally sprays out from the nozzle on the cleaning pipe 196. The liquid in the acid tank 192 is dilute hydrochloric acid. Spray 1% to 2% dilute hydrochloric acid evenly on the surface of the inclined tube / plate through the fan-shaped nozzle. "The amount of acid used is 0.5 to 1L per square meter of inclined plate" to ensure full contact with the scale.

[0130] 3. Let stand for 10-15 minutes for the chemical dissolution reaction:

[0131] The reaction MgNH4PO4 + 3HCl → MgCl2 + NH4Cl + H3PO4 dissolves hard scale.

[0132] Restart the backflushing process with clean water to rinse away any residual acid and dissolved scale until the pH of the effluent rises back to 6-7.

[0133] Backflushing wastewater treatment:

[0134] The acidic and scale-containing wastewater generated by backflushing is returned to the first pH adjustment tank 9 through the bottom pipe, mixed with the original wastewater and then re-treated to avoid secondary pollution.

[0135] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0136] The embodiments described above are merely illustrative of several implementations of this utility model, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of this utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.

Claims

1. A nitrogen and phosphorus recovery device for wastewater treatment, characterized in that, include: The air flotation system is used to remove residues from the wastewater by forming an air flotation process. The first pH adjustment tank is used to adjust the wastewater to a preset pH value after passing through the air flotation system. Wastewater that has passed through the first pH adjustment tank enters the coagulation tank. Reactive materials are added to the coagulation tank, which is used to fully mix the wastewater and the reactive materials. The wastewater that has passed through the coagulation tank enters the crystallization tank, which is used to crystallize the wastewater. The sedimentation tank is used to separate the crystals from the wastewater after passing through the crystallization tank. The second pH adjustment tank is where the wastewater that has passed through the sedimentation tank enters. The second pH adjustment tank is used to adjust the pH value of the wastewater.

2. The recycling device according to claim 1, characterized in that, The air flotation system includes: a reaction tank, a transition tank, a contact tank, an air flotation tank, and a dissolved air component; The wastewater to be treated enters the reaction tank, which is used to cause the fine suspended solids and colloidal particles in the wastewater to undergo a flocculation reaction, forming large-diameter flocs that can be adsorbed by bubbles. The transition pool is provided between the reaction pool and the contact pool; the transition pool is used to avoid the turbulence of the reaction pool from impacting the subsequent microbubble and floc bonding process in the contact pool. The contact pool is used to allow the microbubbles to come into full contact with and adhere to the flocs, forming a "bubble-floc" composite. The flotation tank is used to achieve solid-liquid separation, causing the composite to float to the water surface and form scum; The dissolved air component is used to provide the microbubbles in the air flotation system.

3. The recycling device according to claim 2, characterized in that, The air flotation system also includes: a slag scraper and a slag skimming tank; The scum scraper is installed on the flotation tank, and the scum skimming trough is installed on the side of the flotation tank. The scum scraper is used to scrape the scum in the flotation tank into the scum skimming trough.

4. The recycling device according to claim 1, characterized in that, The recycling device also includes a stirrer installed on the crystallization tank and a guide tube installed inside the crystallization tank; The guide tube is open at both ends, and there is a gap between the bottom of the guide tube and the bottom wall of the crystallization tank. The stirring blades of the agitator are located inside the guide tube. By starting the agitator, positive and negative pressures are formed on the upper and lower sides of the guide tube, thereby causing the wastewater in the crystallization tank to circulate up and down.

5. The recycling device according to claim 1, characterized in that, The recycling device also includes a sludge hopper at the bottom of the sedimentation tank and a sludge scraper on the sedimentation tank, the sludge scraper being used to scrape the sludge in the sedimentation tank toward the sludge hopper.

6. The recycling device according to claim 5, characterized in that, The recycling device also includes a reflux assembly for returning a portion of the sludge in the sludge hopper to the crystallization tank.

7. The recycling device according to claim 6, characterized in that, The reflux assembly includes a second reflux pipe, a sludge reflux pump, and a first reflux pipe; The inlet of the sludge return pump is connected to one end of the second return pipe, and the other end of the second return pipe is connected to the sludge hopper. The output port of the sludge return pump is connected to one end of the first return pipe, and the other end of the first return pipe is connected to the crystallization tank.

8. The recycling device according to claim 5, characterized in that, The recycling device also includes a cleaning component for cleaning the sludge scraper.

9. The recycling device according to claim 1, characterized in that, The sedimentation tank is an inclined tube or inclined plate sedimentation tank.

10. The recycling device according to claim 2, characterized in that, A mixer is installed on each of the reaction tank, the first pH adjustment tank, the coagulation tank, and the second pH adjustment tank.

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