Filtration, adsorption, phosphorus removal, nitrogen removal and nitrogen and phosphorus recovery system and method for water body

Abstract

The invention discloses a system and a method for filtering, adsorbing, dephosphorizing, denitrifying and recovering nitrogen and phosphorus of a water body. The system is composed of a filtering device, a lifting pump, an adsorbing, dephosphorizing and phosphorus recovering device and an ion exchange denitrification and nitrogen recovering device. The device is mainly used for dephosphorization and denitrification of inferior V-type water bodies with overproof total nitrogen and total phosphorus in large rivers, lakes and reservoirs and sea areas, and water quality is improved, so that the water quality reaches surface III-type or II-type water quality in Environmental Quality Standards for Surface Water (GB3838-2002). According to the present invention, after the system is adopted to perform phosphorus removal and nitrogen removal purification on the water body of the large river, the CODCr of the effluent is less than or equal to 15 mg / L, the BOD5 is less than or equal to 4 mg / L, the phosphorus is less than or equal to 0.1 mg / L, the ammonia nitrogen is less than or equal to 0.5 mg / L, the total nitrogen is less than or equal to 0.5 mg / L, and the pH value is 6-9, and after the nitrogen removal and phosphorus removal purification is performed on the water body of the lake reservoir and the sea area, the CODCr of the effluent is less than or equal to 15 mg / L, the BOD5 is less than or equal to 4 mg / L, the phosphorus is less than or equal to 0.025 mg / L, the ammonia nitrogen is less than or equal to 0.5 mg / L, the total nitrogen

Description

Technical Field

[0001] This invention relates to a water filtration and adsorption system and method for phosphorus and nitrogen removal and recovery, which is used for phosphorus and nitrogen removal in large water bodies such as rivers, lakes and reservoirs, and belongs to the fields of water environment management, water resource purification and resource recycling. Background Technology

[0002] Rivers, lakes, reservoirs, and other water bodies turn black and smelly due to excessive pollution exceeding their water environment capacity. They are usually below the Class V water quality standard of the "Surface Water Environmental Quality Standard" (GB3838-2002). Their main characteristic indicators are dissolved oxygen less than 2.0 mg / L, ammonia nitrogen greater than 2.0 mg / L, or total phosphorus greater than 0.4 mg / L. They are mostly located in densely populated areas with high pollution load intensity and incomplete infrastructure, mainly including urban built-up areas, urban-rural fringe areas, county towns, and central towns, as well as concentrated areas of aquaculture and livestock farming.

[0003] Nitrogen and phosphorus are key substances causing eutrophication in rivers, lakes, reservoirs, and nearshore waters. They are crucial elements leading to water quality deterioration, continuous algal blooms, algal blooms and red tides, and damage to the aquatic ecosystem, threatening the survival of humans and aquatic life. In recent years, the cyanobacterial bloom in Taihu Lake severely impacted drinking water for residents and tourism in the surrounding area. Year after year, cyanobacterial blooms in lakes such as Dianchi Lake in Yunnan and Chaohu Lake in Anhui have seriously threatened the lives and safety of humans and aquatic life. Furthermore, nearshore waters have repeatedly experienced red tides due to excessive nitrogen and phosphorus levels and overgrowth of algae. Therefore, removing phosphorus and nitrogen from water bodies is a key method for controlling eutrophication and preventing cyanobacterial blooms, algal blooms, and red tides. Analysis of water quality data from national sections reveals four main types of water quality issues: 1. Total phosphorus exceeds standards, while other indicators are within acceptable limits; 2. Ammonia nitrogen and total phosphorus exceed standards, dissolved oxygen does not meet standards, while other indicators are within acceptable limits; 3. Total phosphorus and total nitrogen exceed standards, while other indicators are within acceptable limits; 4. Ammonia nitrogen, total phosphorus, and total nitrogen exceed standards, while other indicators are within acceptable limits.

[0004] Currently, phosphorus removal methods for water bodies are generally classified into physical, chemical, and biological or combined methods. Physical methods mainly include membrane filtration, ion exchange, and filtration adsorption; chemical methods mainly include precipitation, flotation, and evaporation crystallization; biological methods involve the cultivation of polyphosphate-accumulating bacteria (PACs) under aerobic or anoxic conditions, where these microorganisms excessively absorb phosphate from the water, storing energy as the high-energy substance ATP. A portion of the phosphorus is converted into polyphosphate, stored as energy within the cells, and biological phosphorus removal is achieved through the discharge of excess sludge. Chemical phosphorus removal is one of the current methods for removing phosphorus from water bodies, but it has drawbacks such as the use of large amounts of chemical agents, the generation of large amounts of sludge, and the fact that the phosphorus concentration in the treated water remains between 0.2 and 0.5 mg / L, resulting in low effluent quality but high costs. Membrane filtration can achieve phosphorus concentration and phosphorus resource recovery, but it suffers from high fixed asset investment and high operating costs. Currently, methods for removing total nitrogen from water bodies include physical, chemical, and biological methods, or a combination of two or three. Physical methods mainly include evaporation crystallization and freeze crystallization; chemical methods mainly include ion exchange and electrolysis; biological methods mainly include nitrification and denitrification. Because phosphorus and nitrogen removal in large water bodies such as rivers, lakes, and large reservoirs requires operating costs as low as 0.15 yuan / m³, this is crucial. 3 The following methods are used to remove phosphorus and nitrogen from rivers, lakes, and reservoirs without producing sediment or causing secondary pollution. Currently, river phosphorus and nitrogen removal projects mainly involve removing silt from the bottom of the water body, drying and transporting the silt off-site, or piling it into small islands in lakes. Simultaneously, methods such as raising aquatic animals and planting aquatic plants in shallow water areas are employed, but the results have been unsatisfactory.

[0005] Therefore, in order to ensure the water quality of rivers, lakes and reservoirs, reduce operating costs and realize the recovery of nitrogen and phosphorus resources, there is an urgent need for a device and its usage method that can quickly and efficiently remove phosphorus and nitrogen from water bodies, based on the characteristics of rivers, lakes and reservoirs, and with low operating costs. Summary of the Invention

[0006] To address the problems described in the background art, the present invention aims to provide a system and method suitable for phosphorus and nitrogen removal and nitrogen and phosphorus recovery in large water bodies such as rivers, lakes (reservoirs) that are prone to exceeding the standards for total phosphorus and total nitrogen. This system and method enables efficient phosphorus and nitrogen removal in large water bodies such as rivers, lakes, and reservoirs, and the recovery and utilization of nitrogen and phosphorus resources in the water, thereby rapidly improving the water quality to Class II or III of the "Surface Water Environmental Quality Standard" (GB3838-2002).

[0007] This invention provides a water filtration, adsorption, phosphorus removal, denitrification, and nitrogen and phosphorus recovery system, characterized in that it comprises: a filtration device, an adsorption phosphorus removal device and a phosphorus recovery device, an ion exchange denitrification device and a nitrogen recovery device, wherein the filtration device, the adsorption phosphorus removal device and the phosphorus recovery device, the ion exchange denitrification device and the nitrogen recovery device are connected in sequence.

[0008] in:

[0009] The filtration device is used to filter out solid particles and colloids in the water, preventing solid particles and colloids in the water from polluting and clogging the packing of the adsorption phosphorus removal device; the filtration device is provided with an inlet, an outlet, a filter residue rinsing water inlet, and a filter residue rinsing water outlet; the inlet of the filtration device is connected to the water body, and the filtration device is equipped with a lift pump, the outlet of which is connected to the inlet of the adsorption phosphorus removal and phosphorus recovery device.

[0010] The phosphorus adsorption device is used to filter and adsorb total phosphorus from water. The device includes a phosphorus adsorption bed, a phosphorus adsorption bed inlet, a phosphorus adsorption bed outlet, a support frame, an aeration pipe, a grid plate, a screen, and phosphorus adsorption filter media. The support frame supports the grid plate, the grid plate supports the screen, and the filter media is supported. The inlet of the phosphorus adsorption bed is connected to the outlet of the booster pump, and the outlet of the phosphorus adsorption bed is connected via a four-way valve to the outlet of the clear water storage tank, the inlet of the eluent storage tank, and the inlet of the anion exchange tower.

[0011] The phosphorus recovery device is used to recover phosphorus eluted from the phosphorus adsorption packing. The phosphorus recovery device includes a first regeneration system, a first clean water backwashing system, and a phosphorus precipitation recovery system connected in sequence. The first regeneration system is used to regenerate the phosphorus adsorption filter media in the phosphorus removal bed. The first regeneration system includes a regeneration liquid storage tank, an eluent storage tank, and a clean water storage tank. The outlet of the regeneration liquid storage tank is connected to the inlet of the phosphorus adsorption bed. The regeneration liquid storage tank is also connected in sequence to a regeneration liquid recovery tank, a sedimentation tank, and a dewatering machine. The outlet of the dewatering machine is connected to a drainage metering tank, and the solid outlet of the dewatering machine is connected to the inlet of a packaging machine.

[0012] The first clean water backwashing and regeneration system is used to remove the residual regeneration solution in the adsorption and phosphorus removal packing in the adsorption and phosphorus removal bed after regeneration with regeneration solution. The first clean water backwashing and regeneration system includes a clean water storage tank and a backwashing pump; the inlet of the clean water storage tank is connected to the outlet of the adsorption and phosphorus removal bed, and the outlet of the clean water storage tank is connected to the phosphorus precipitation and recovery system.

[0013] The ion exchange denitrification device includes an anion exchange tower. The phosphorus-removed water after being adsorbed and dephosphorized by the adsorption phosphorus removal device enters the ion exchange tower for removing total nitrogen from the water through ion exchange.

[0014] The nitrogen recovery device includes an ion exchange regeneration system, a second clean water backwashing system, and an ion exchange resin eluent system.

[0015] Preferably, the anion exchange tower includes anion exchange tower body, inlet, outlet, bottom column, sieve plate support, lower sieve plate, anion exchange resin, upper sieve plate, and tower cover plate. The bottom column supports the anion exchange tower body, the sieve plate support supports the lower sieve plate, the lower sieve plate supports the anion exchange resin, and the upper sieve plate encloses the anion exchange resin in the ion exchange tower. The phosphorus-removed water, after adsorption and phosphorus removal, enters the ion exchange tower body through the inlet and reacts with the anion exchange resin in the tower body. Nitrate and nitrite anions in the water combine with the anion exchange resin and are adsorbed onto the anion exchange resin.

[0016] Preferably, the anion exchange resin is used to adsorb anions such as nitrate and nitrite in the water body to the anion exchange resin through ion exchange, thereby achieving denitrification of the water body; the anion exchange resin is one of D401, D205 macroporous strong base anion exchange resin, D890, LSI-106 weak base macroporous anion exchange resin, and strong base anion exchange resin.

[0017] Preferably, the filtration adsorption phosphorus removal system is an adsorption phosphorus removal system composed of 1 to N filtration adsorption towers; the number of phosphorus adsorption beds is 1 to N, where N is an integer from 2 to 12; the 1 to N adsorption towers are arranged in one, two, or three rows in sequence.

[0018] Preferably, the aperture of the screen is 2-5 mm.

[0019] Preferably, the regenerated liquid storage tank is connected in sequence to the regenerated liquid recovery tank, the sedimentation tank, and the dewatering machine. The outlet of the regenerated liquid storage tank is connected to the inlet of the regenerated liquid recovery tank, the outlet of the regenerated liquid recovery tank is connected to the inlet of the sedimentation tank, the outlet of the sedimentation tank is connected to the inlet of the dewatering machine, the outlet of the dewatering machine is connected to the drainage metering tank, and the solid outlet of the dewatering machine is connected to the inlet of the packaging machine.

[0020] Preferably, the ion exchange resin eluent system includes a reverse osmosis total nitrogen concentration system and a nitrate nitrogen evaporation and crystallization system.

[0021] The reverse osmosis total nitrogen concentration system is used to recover the regenerated liquid in the storage tank by concentrating the regenerated liquid through the membrane, and to separate the regenerated liquid into a reverse osmosis concentrate and a dialysate with a high total nitrogen concentration through reverse osmosis. The reverse osmosis total nitrogen concentration system consists of at least a high-pressure pump, a reverse osmosis membrane module, a dialysate storage tank, and a concentrate storage tank. The inlet of the high-pressure pump of the reverse osmosis total nitrogen concentration system is connected to the outlet of the regenerated liquid recovery storage tank; the outlet of the high-pressure pump of the reverse osmosis total nitrogen concentration system is connected to the inlet of the reverse osmosis membrane module; the dialysate outlet of the reverse osmosis membrane module is connected to the inlet of the dialysate storage tank; and the concentrate outlet of the reverse osmosis membrane module is connected to the inlet of the concentrate storage tank.

[0022] Preferably, the nitrate nitrogen evaporation crystallization system is used to recover total nitrogen, mainly nitrate nitrogen, from reverse osmosis concentrate through evaporation crystallization. The nitrate nitrogen evaporation crystallization system comprises a booster pump, a heat exchanger, an evaporator, a crystallizer, a centrifuge, and a mother liquor storage tank. The inlet of the booster pump is connected to the outlet of the concentrate storage tank, and the outlet is connected to the inlet of the heat exchanger. The outlet of the heat exchanger is connected to the inlet of the evaporator, the concentrate outlet of the evaporator is connected to the inlet of the crystallizer, and the outlet of the crystallizer is connected to the inlet of the centrifuge. The centrifuge crystallizes and separates the nitrates in the crystallizer into solid nitrates and mother liquor. The solid nitrates are the recovered total nitrogen. The steam outlet of the evaporator is connected to the inlet of the condenser, and the outlet of the condenser is connected to the condensate storage tank.

[0023] Preferably, the filtration device is one of multi-media filtration, fiber filter cartridge filtration, filter cloth filter bed filtration, rotary disc filtration, microfiltration or ultrafiltration;

[0024] Preferably, the phosphorus adsorption bed (2-1) is composed of a square, rectangular or circular bed body, and is a hollow column made of steel plate, stainless steel plate, aluminum plate, fiberglass or PE; the upper part of the filter adsorption tower (barrel) is provided with a water inlet and a sewage outlet; the lower part of the phosphorus adsorption bed is provided with a clean water outlet, a regenerated liquid inlet, a sewage outlet and an aeration port.

[0025] Preferably, the adsorption and phosphorus removal packing material of the adsorption and phosphorus removal bed includes porous calcium-based expanded adsorption and phosphorus removal packing material and ferric hydroxide expanded adsorption and phosphorus removal packing material; the porous calcium-based expanded adsorption and phosphorus removal packing material has a honeycomb porous structure, and is made by expanding, crushing, and sieving 10-15% by weight of activated diatomaceous earth as adsorbent, 25-38% by weight of gypsum powder as total phosphorus adsorbent, 25-30% by weight of cement as binder, 21.5-29.5% by weight of stone powder as aggregate, and 0.5% by weight of foaming agent, and its main technical indicators are: bulk density of 430-650 kg / m³. 3 Specific surface area ≥ 11.5 m² 2 / g, compressive strength ≥2.5MPa, porosity ≥75%, dry density ≤800kg / m³ 3 The water absorption rate is ≥35%, and the particle size range is 5-40mm. The expanded hydroxyl oxide adsorption phosphorus removal filler has a honeycomb-like porous structure. Its raw materials include 25-28% gypsum powder and 20-25% hydroxyl oxide as phosphorus adsorbent, 20-25% cement as binder, 21.5-26.5% stone powder as aggregate, and 0.5% foaming agent. It is produced by expansion molding, crushing, and sieving. Its main technical indicators are: bulk density of 430-650 kg / m³. 3 Specific surface area ≥12.5m² 2 / g, compressive strength ≥3.5MPa, porosity ≥75%, dry density ≤800kg / m³ 3 Water absorption rate ≥35%, particle size range 3~40mm.

[0026] On the other hand, this application also provides a method for phosphorus and nitrogen removal and recovery of water bodies, which utilizes the above-mentioned water body filtration and adsorption phosphorus and nitrogen removal and recovery system, and processes the water according to the following steps:

[0027] (1) Filtration: River and lake (reservoir) water containing 0.3-3 mg / L total phosphorus and 1-5 mg / L total nitrogen flows into the filtration device to filter out small solid particles and colloids in the water, and prevent small solid particles and colloids in the water from contaminating the phosphorus adsorption packing in the filtration adsorption tower.

[0028] (2) Phosphorus Adsorption: Open the inlet and outlet valves, close the backwash liquid inlet and outlet valves, and introduce the river / lake (reservoir) water filtered in step (1) into the phosphorus adsorption bed (2-1) of the phosphorus adsorption device (2). At the same time, turn on the blower for aeration. The phosphorus-nitrogen-containing water flows out from top to bottom. The phosphate anions in the water are adsorbed by the phosphorus adsorption filter material in the phosphorus adsorption bed (2-1), thereby removing the phosphate in the water. The phosphorus-removed water enters the phosphorus-removed water pool or storage tank after being metered by the outlet and outlet valve of the phosphorus adsorption bed (2-1). Reaction formula (adsorption reaction):

[0029] FeO-OH+H2PO4 - =Fe-O-HPO4 - +H2O

[0030] After filtration and adsorption for phosphorus removal, the effluent contains COD≦20mg / L, ammonia nitrogen≦1mg / L, and total phosphorus≦0.1mg / L (for river water) or 0.025mg / L (for lake and reservoir water), with a phosphorus removal rate of 90-99.5%.

[0031] (3) Anion exchange denitrification: The dephosphorized water that has undergone filtration and adsorption dephosphorization in step (2) and is stored in the dephosphorized water pool or tank is pumped into the anion exchange tower. Nitrate and nitrite anions in the water are removed by anion exchange, thereby achieving total nitrogen removal from the water. The clear water after total nitrogen removal by anion exchange enters the denitrified water storage tank or flows into a natural water body after being metered by the flow meter through the outlet and outlet valve of the ion exchange tower. After denitrification by anion exchange, the COD in the effluent is ≤20mg / L, ammonia nitrogen is ≤0.5mg / L, total nitrogen is ≤1mg / L, and total phosphorus is ≤0.1mg / L (river) or 0.025mg / L (lake / reservoir). The total nitrogen removal rate is 80-99.0%.

[0032] (4) Regeneration of the filter adsorption packing: Monitor the total phosphorus concentration of the effluent regularly. When the total phosphorus concentration approaches the set value, first shut off the booster pump, then close the inlet valve and backwash liquid valve. Open the outlet valve of the backwash desorption device. Use the backwash pump to pump the alkaline washing regeneration liquid (extraction liquid) into the phosphorus adsorption bed until the liquid level is reached. Turn off the regeneration pump, aerate for 5 minutes, stop aeration and soak for 10 minutes, then aerate for another 5 minutes, stop aeration and soak for 10 minutes, repeating this process 4-6 times for a total backwash regeneration of 60 minutes. After 90 minutes, the phosphate ions adsorbed in the adsorption packing are eluted, and the eluent regeneration solution is pumped into the reaction tank of the phosphorus recovery unit. After desorption, the solution is washed with water until neutral. After alkaline washing regeneration, the acid washing regeneration solution (elution solution) is pumped into the phosphorus adsorption bed to the liquid level using a backwash pump. The backwash regeneration lasts for 30-60 minutes, during which the calcium phosphate adsorbed in the adsorption packing is eluted, and the eluent regeneration solution is pumped into the acid washing solution recovery tank. After acid washing regeneration, the solution is backwashed with water until neutral, thus completing the regeneration of the adsorption packing.

[0033] (5) Phosphorus recovery: The backwash desorption liquid regenerated from the adsorption phosphorus removal packing is pumped into the reaction tank of the phosphorus recovery device, a phosphorus precipitant is added, and the reaction is stirred to allow the phosphate ions in the recovery liquid to react with calcium ions to form calcium phosphate precipitate. The backwash desorption liquid after the reaction is injected into the precipitation tank, the precipitate is separated, and dried to obtain the recovered calcium phosphate. The phosphorus precipitant is a clear saturated calcium hydroxide solution or a 5-25% calcium chloride solution.

[0034] Reaction formula (precipitation crystallization reaction):

[0035] 2PO4 3- +3Ca(OH)2=Ca3(PO4)2+6OH -

[0036] In summary, the principle of phosphorus removal from water is as follows:

[0037] Removal of phosphorus from wastewater (adsorption reaction)

[0038] FeO-OH+H2PO4 - =FeO-HPO4 - +H2O

[0039] Adsorbent regeneration (desorption reaction)

[0040] FeO-HPO4 - +3OH - =FeO-OH+PO4 3- +OH - +H2O

[0041] Phosphorus resource recovery (flocculation and crystallization reaction)

[0042] 2PO4 3-+3Ca(OH)2=Ca3(PO4)2+6OH -

[0043] The phosphorus precipitant is a clear saturated calcium hydroxide solution or a 5-25% calcium chloride solution.

[0044] The total phosphorus removal rate of the phosphorus filtration and adsorption device is greater than 90% after filtration and purification. Specifically: after water with a total phosphorus concentration greater than 1 mg / L is filtered and purified by the phosphorus filtration and adsorption device of the present invention, the total phosphorus concentration in the effluent is less than 0.2 mg / L; after water with a total phosphorus concentration of 0.5 to 1 mg / L is filtered and purified by the phosphorus filtration and adsorption device of the present invention, the total phosphorus concentration in the effluent is less than 0.1 mg / L; and after water with a total phosphorus concentration less than 0.5 mg / L is filtered and purified by the phosphorus filtration and adsorption device of the present invention, the total phosphorus concentration in the effluent is less than 0.025 mg / L.

[0045] (6) Regeneration of anion exchange resin: Monitor the total nitrogen concentration of the effluent from the ion exchange tower in a timely manner. When the total nitrogen concentration of the effluent approaches the set value, first shut off the booster pump, then shut off the inlet valve and the backwash liquid valve, and open the outlet valve of the backwash desorption device. Use the backwash pump to pump 5-10% sodium chloride regeneration solution (elution solution) into the anion exchange tower to the liquid level, shut off the regeneration pump, aerate for 5 minutes, stop aeration and soak for 15 minutes, aerate for another 5 minutes, stop aeration and soak for 15 minutes, repeat four to six times, and backwash regeneration for a total of 60-90 minutes to elute the nitrate adsorbed in the anion exchange resin. The eluent regeneration solution is pumped into the reverse osmosis device for total nitrogen recovery, and separated into a 10-20% concentrate (high-concentration total nitrogen water) and an 80-90% dialysate through reverse osmosis filtration. The concentrate (high-concentration total nitrogen water) is pumped into the evaporation crystallization system to crystallize and recover nitrate.

[0046] Preferably, after step (6), the following steps are further included:

[0047] (7) Reverse osmosis concentration of anion exchange resin regenerated solution: The total nitrogen-rich regenerated solution generated from the regeneration of anion exchange resin in step (7) is pumped into the reverse osmosis total nitrogen concentration system. The regenerated solution is separated into 10-20% concentrate and 80-90% dialysate through the reverse osmosis total nitrogen concentration system.

[0048] (8) Evaporation and crystallization of nitrates in the concentrate: The concentrate obtained from the reverse osmosis total nitrogen concentration system in step (8) is pumped into the heat exchanger of the evaporation and crystallization system, and then into the evaporator. After evaporation and concentration, it enters the crystallization tank and crystallizes out solid nitrates.

[0049] (9) Centrifugal separation: The concentrated liquid after evaporation and crystallization in step (9) is pumped into a centrifuge and separated by centrifugation to obtain nitrate solid and mother liquor.

[0050] The water filtration and adsorption phosphorus and nitrogen removal system and method disclosed in this application have the following outstanding advantages:

[0051] 1. High-quality effluent: After purifying nitrogen- and phosphorus-containing water bodies in rivers, lakes, or reservoirs using this invention, the total nitrogen in river water is less than 1 mg / L and the total phosphorus is less than 0.2 mg / L, while the total nitrogen in lake and reservoir water is less than 1 mg / L and the total phosphorus is less than 0.025 mg / L. This solves the problem of nitrogen and phosphorus treatment in rivers, lakes, and reservoirs, and the water quality meets the surface water quality standard (GB3838-2002) of Surface Water Environmental Quality Standard III. It also solves the problem of phosphorus and nitrogen removal and eutrophication treatment in large water bodies such as rivers and lakes.

[0052] 2. Simple process: After filtering nitrogen and phosphorus-containing water to remove particulate solids and colloids, the liquid is directly passed through a phosphorus filtration adsorption tower for phosphorus removal, and then through anion exchange for nitrogen removal. This process can ensure that the total phosphorus in the treated water is less than 0.1 mg / L and the total nitrogen is less than 1 mg / L. The process is simple.

[0053] 3. Phosphorus and nitrogen resources are recovered: During the water filtration and adsorption process for phosphorus and nitrogen removal, phosphorus is adsorbed onto a special phosphorus adsorption packing. After saturation, it is eluted and regenerated using a 0.5-1% sodium hydroxide solution. The phosphorus is transferred to the sodium hydroxide solution. Saturated lime water or calcium chloride is added to the sodium hydroxide solution, and phosphate ions react with calcium ions to form calcium phosphate precipitate, thereby recovering phosphorus resources. Total nitrogen is ion-exchanged onto anion exchange resin. After saturation, it is eluted and regenerated, and the nitrogen is transferred to the regenerated solution. Then, it is separated, concentrated, and evaporated for crystallization through reverse osmosis to recover nitrate nitrogen. The entire process produces no sludge. Attached Figure Description

[0054] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. (Appendix) Figure 1 This is a schematic diagram of a water filtration, adsorption, phosphorus removal, denitrification, and nitrogen and phosphorus recovery system according to this application;

[0055] Appendix Figure 2 This is a schematic diagram of an adsorption phosphorus removal device for a water filtration, adsorption, phosphorus removal, denitrification, and nitrogen and phosphorus recovery system according to this application.

[0056] Appendix Figure 3 This is a schematic diagram of a phosphorus recovery device in a water filtration, adsorption, phosphorus removal, denitrification, and nitrogen and phosphorus recovery system according to the present invention.

[0057] Appendix Figure 4 This is a schematic diagram of an ion exchange tower in a water filtration and adsorption system for phosphorus and nitrogen removal according to the present invention.

[0058] Appendix Figure 5 This is a schematic diagram of an ion exchange tower regeneration system for a water filtration, adsorption, phosphorus removal, nitrogen and phosphorus recovery system according to the present invention.

[0059] Appendix Figure 6 This is a schematic diagram of a reverse osmosis concentration device for a water filtration, adsorption, phosphorus removal, denitrification, and nitrogen and phosphorus recovery system according to the present invention; (See attached diagram) Figure 7 This is a schematic diagram of the evaporation and crystallization of a water filtration, adsorption, phosphorus removal, denitrification, and nitrogen and phosphorus recovery system according to the present invention.

[0060] Appendix Figure 8 This is a process flow diagram of a water filtration, adsorption, phosphorus removal, denitrification, and nitrogen and phosphorus recovery system according to the present invention.

[0061] The components include: 1. Filtration device; 2. Adsorption phosphorus removal device; 3. Phosphorus recovery device; 4. Ion exchange denitrification device; 5. Nitrogen recovery device; 2-1. Phosphorus adsorption bed; 2-2. Phosphorus adsorption bed inlet; 2-3. Phosphorus adsorption bed outlet; 2-4. Support frame; 2-5. Aeration pipe; 2-6. Grating plate; 2-7. Screen; 2-8. Adsorption phosphorus removal filter media; 311. Inlet valve; 313. Four-way valve; 314. Dosing pump; 312. 315, 317, 320, 321, 324, 327 Valves; 316, 332 Water Pumps; 318 Regenerated Liquid Storage Tank; 319 Clear Water Storage Tank; 322 Eluent Storage Tank; 323 Water Pumps; 325 Reaction Tank; 326 Chemical Dosing Tank; 328 Mixer; 329 Dehydrator; 330 Water Pumps; 331 Intermediate Storage Tank; 4-1 Tower Body; 4-2 Inlet; 4-3 Outlet; 4-4 Upper... 4-5. Sieve plate; 4-6. Anion exchange resin; 4-7. Lower sieve plate; 4-8. Tower cover plate; 4-9. Sieve plate support; 4-10. Drain valve; 512. Tower bottom column; 519. Four-way valve; 513. Valves; 514. Regenerated liquor storage tank; 522. Dosing pump; 528. Eluent storage tank; 611. Valves; 612. High-pressure pump; 613. Reverse osmosis. Membrane module, 614, valve, 615, dialysate storage tank, 616, valve, 617, concentrate storage tank; 711, valve, 712, booster pump, 713, heat exchanger, 714, valve, 715, evaporator, 720, condenser, 721, valve, 722, condensate storage tank, 716, valve, 717, crystallizer, 719, centrifuge, 723, valve, 724, mother liquor storage tank, 725, packaging machine. Detailed Implementation

[0062] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0063] For the terms defined below, unless a different definition is given elsewhere in the claims or this specification, these definitions shall apply. All numerical values, whether explicitly indicated or not, are defined herein as being modified by the term "about." The term "about" generally refers to a range of numerical values ​​that a person skilled in the art would consider equivalent to the stated values ​​to produce substantially the same properties, functions, results, etc. A range of numerical values ​​indicated by a low value and a high value is defined as including all numerical values ​​included within that range and all subranges included within that range.

[0064] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion.

[0065] See appendix Figure 1 and Figure 8 A water filtration and adsorption phosphorus removal and nitrogen recovery system, characterized in that it comprises a filtration device 1, an adsorption phosphorus removal device 2, a phosphorus recovery device 3, an ion exchange denitrification device 4, and a nitrogen recovery device 5, wherein:

[0066] The filter device 1 is used to filter and remove solid particles and colloids from the water, preventing solid particles and colloids in the water from polluting and clogging the packing of the adsorption and phosphorus removal device. The filter device is equipped with an inlet, an outlet, a filter residue rinsing water inlet, and a filter residue rinsing water outlet. The inlet of the filter device is connected to the water body, and a lift pump is installed in the water collection well of the filter device. The outlet of the lift pump is connected to the inlet of the filtration and adsorption phosphorus removal device.

[0067] See Figure 2The phosphorus adsorption device 2 is used to filter and adsorb total phosphorus from water. The phosphorus adsorption device 2 includes a phosphorus adsorption bed 2-1, a phosphorus adsorption bed inlet 2-2, an outlet 2-3, a support 2-4, an aeration pipe 2-5, a grid plate 2-6, a screen 2-7, and phosphorus adsorption filter media 2-8. The support 2-4 supports the grid plate 2-6, the grid plate 2-6 supports the screen 2-7, and the screen 2-7 has a pore size of 2-5 mm and supports the phosphorus adsorption filter media 2-8. The inlet 2-2 of the adsorption bed is connected to the outlet of the filter device via a four-way valve 311. The outlet 2-3 of the phosphorus adsorption bed 2-1 is connected to the inlet of the anion exchange tower 4-1 of the ion exchange denitrification device 4 via a four-way valve 313.

[0068] See Figure 3 The phosphorus recovery device 3 is used to recover phosphorus eluted from the phosphorus adsorption packing. The phosphorus recovery device includes a first regeneration system, a first clean water backwashing system, and a phosphorus precipitation recovery device. The first regeneration system of the phosphorus recovery device 3 consists of a regenerated liquid storage tank 318, an eluent storage tank 322, and a clean water storage tank 319, used to elute phosphorus adsorbed in the phosphorus removal filter media 2-8 and store it in the eluent storage tank 322. The outlet of the regenerated liquid storage tank 318 is connected to a dosing pump 314, which is connected to a valve 315, which is connected to the inlet 2-2 of the phosphorus removal bed via a four-way valve. Furthermore, the regenerated liquid storage tank 318 is sequentially connected to a regenerated liquid recovery tank, a sedimentation tank, and a dewatering machine. In some embodiments, the outlet of the regenerated liquid storage tank 318 is connected to the inlet of the regenerated liquid recovery tank, the outlet of the regenerated liquid recovery tank is connected to the inlet of the sedimentation tank, the outlet of the sedimentation tank is connected to the inlet of the dewatering machine, the outlet of the dewatering machine is connected to the drainage metering tank, and the solid outlet of the dewatering machine is connected to the inlet of the packaging machine. The first clean water backwashing regeneration system is used to remove residual regenerated liquid from the adsorption phosphorus removal packing material in the adsorption phosphorus removal bed after regeneration with regenerated liquid. The first clean water backwashing regeneration system includes a clean water storage tank 319 and a backwash pump. The outlet of the clean water storage tank 319 is connected to the outlet 2-3 of the adsorption phosphorus removal bed.

[0069] The outlet 2-3 of the adsorption phosphorus removal bed is connected to one port of the four-way valve 313, and one port of the four-way valve 313 is connected to the valve 320. The valve 320 is connected to the eluent storage tank 322. In the first clear water backwashing and regeneration system, the clear water storage tank 319, backwash pump 316, valve 317, four-way valve 313, adsorption phosphorus removal device 2, outlet valve 321 and eluent storage tank 322 are connected. The phosphorus precipitation recovery device consists of a water pump 323, valve 324, reaction tank 325, phosphorus precipitant dosing tank 326, valve 327, a mixer 328, a dewatering machine 329, a water pump 330 and an intermediate storage tank 331.

[0070] See Figure 4The ion exchange device 4 is used to remove nitrate and nitrite nitrogen from water through anion exchange, and includes an anion exchange tower. The outlet 2-3 of the adsorption and phosphorus removal bed is connected to the inlet of the anion exchange tower. The outlet of the anion exchange tower is discharged into a natural water body via a four-way outlet. The anion exchange tower comprises an anion exchange tower body 4-1, an inlet 4-2, an outlet 4-3, a tower bottom column 4-10, a sieve plate support 4-8, a lower sieve plate 4-6, anion exchange resin 4-5, an upper sieve plate 4-4, and a tower cover plate 4-7. The tower bottom column 4-10 supports the anion exchange tower body 4-1, and the sieve plate support 4-8 supports the lower sieve plate. 4-6, the lower sieve plate 4-6 is used to support the anion exchange resin 4-5, and the upper sieve plate 4-4 is used to enclose the anion exchange resin in the ion exchange tower. The outlet 2-3 of the adsorption and phosphorus removal bed is connected to the inlet 4-2 of the anion exchange tower. The phosphorus-removed water after adsorption and phosphorus removal enters the tower body 4-1 of the ion exchange tower through the inlet 4-2 and reacts with the anion exchange resin in the tower body. The nitrate anions and nitrite anions in the water combine with the anion exchange resin and are adsorbed on the anion exchange resin.

[0071] Specifically, the ion exchange tower device in the ion exchange device 4 has anion exchange resin 4-5, which is used to adsorb anions such as nitrate and nitrite in the water to the anion exchange resin through ion exchange, thereby realizing denitrification of the water. The anion exchange resin can be any one of D401, D205 macroporous strong base anion exchange resin, D890, LSI-106 weak base macroporous anion exchange resin, and strong base anion exchange resin.

[0072] See Figure 5 The nitrogen recovery device 5 is used to recover total nitrogen, mainly nitrate nitrogen, eluted from the anion exchange resin. The nitrogen recovery device 5 includes an ion exchange regeneration system, a second clean water backwashing system, and an ion exchange resin eluent system, wherein the ion exchange resin eluent system includes a reverse osmosis total nitrogen concentration system and a nitrate nitrogen evaporation crystallization system.

[0073] The ion exchange regeneration system is used for the regeneration of anion exchange resin in the anion exchange tower. It includes a regeneration liquid storage tank 521, a dosing pump 522, a valve 523, a four-way valve 512, an outlet 4-3, a four-way valve 519, a valve 527, and an eluent storage tank 528. The regeneration liquid storage tank 521 is connected to one inlet of the four-way valve 512 via the dosing pump 522 and the valve 523. One outlet of the four-way valve 512 is connected to the inlet 4-2 of the anion exchange tower. The outlet 4-3 of the anion exchange tower 4 is connected to the four-way valve 519. One outlet of the four-way valve 519 is connected to the eluent storage tank 528 via the valve 527.

[0074] The second clean water backwashing system includes a clean water storage tank 524, a water pump 525, a valve 526, and a four-way valve 519. The outlet 4-3 of the anion exchange tower is connected to a natural water body via one of the outlets of the four-way valve 520. When the clean water storage tank 524 is in operation, the outlet 4-3 of the ion exchange resin tower becomes the inlet and is connected to the clean water storage tank 524. The drain outlet of the anion exchange tower 4 is connected to the eluent storage tank 528 via a three-way valve and a valve 529. Specifically, the drain outlet of the anion exchange tower is also equipped with a drain valve 4-9.

[0075] See Figure 6 The reverse osmosis concentration system of the ion exchange resin eluent system is used for the separation and concentration of the eluent from the anion exchange tower. It consists of valve 611, high-pressure pump 612, reverse osmosis membrane module 613, valve 614, dialysate storage tank 615, valve 616, and concentrate storage tank 617. The inlet of valve 611 is connected to the outlet of eluent storage tank 528, the outlet of valve 611 is connected to the inlet of high-pressure pump 612, the outlet of high-pressure pump 612 is connected to the inlet of reverse osmosis membrane module 613, the dialysate outlet of reverse osmosis membrane module 613 is connected to the inlet of dialysate storage tank 615 via valve 614, and the concentrate outlet of reverse osmosis membrane module 613 is connected to the inlet of concentrate storage tank 617 via valve 616.

[0076] See Figure 7 The nitrate nitrogen evaporation crystallization system is used to evaporate and crystallize total nitrogen, mainly nitrate nitrogen, in reverse osmosis concentrate. The system comprises valve 711, lift pump 712, heat exchanger 713, valve 714, evaporator 715, condenser 720, valve 721, condensate storage tank 722, valve 716, crystallization tank 717, centrifuge 719, valve 723, mother liquor storage tank 724, and packaging machine 725. The inlet of valve 711 is connected to the outlet of concentrate storage tank 615, and the outlet of valve 711 is connected to the inlet of lift pump 712. The outlet of the evaporator 713 is connected to the inlet of the heat exchanger 713. The outlet of the heat exchanger 713 is connected to the inlet of the evaporator 713 via valve 714. The steam outlet of the evaporator 713 is connected to the inlet of the condenser 720. The outlet of the condenser 720 is connected to the inlet of the condensate storage tank 722 via valve 721. The concentrated liquid outlet of the evaporator 713 is connected to the inlet of the crystallizer 717 via valve 716. The outlet of the crystallizer 717 is connected to the inlet of the centrifuge 719 via pump 718. The crystallization outlet of the centrifuge 719 is connected to the packaging machine 725. The outlet of the centrifuge 719 is connected to the mother liquor storage tank 724 via valve 723. The steam outlet of the evaporator is connected to the inlet of the condenser, and the outlet of the condenser is connected to the condensate storage tank.

[0077] In some embodiments, the outlet 2-3 of the phosphorus adsorption bed is connected to the inlet 4-2 of the ion exchange tower 4-1 of the anion exchange denitrification device, and the outlet 4-3 of the anion exchange tower 4-1 is connected to the outlet.

[0078] In some embodiments, the anion exchange resin regeneration system is used for the regeneration of anion exchange resin in the ion exchange tower, and consists of a regeneration washing solution storage tank, an ion exchange tower, and a regeneration liquid recovery storage tank; the clean water backwashing system consists of a clean water storage tank, an ion exchange tower, and a cleaning solution recovery storage tank.

[0079] In some embodiments, the reverse osmosis nitrogen concentration system is used to recover the regenerated liquid in the storage tank by concentrating the regenerated liquid through the membrane, and to separate the regenerated liquid into a reverse osmosis concentrate with a high total nitrogen concentration and a dialysate (pure water) by reverse osmosis.

[0080] In some embodiments, the clean water backwash regeneration system is used to remove residual regeneration solution from the anion exchange resin in the ion exchange tower after regeneration with regeneration solution. The clean water backwash regeneration system consists of a clean water tank (barrel) and a backwash pump.

[0081] In some embodiments, the filtration device 1 is one of multi-media filtration, fiber filter cartridge filtration, filter cloth filter bed filtration, fiber disc filtration, microfiltration or ultrafiltration.

[0082] In some embodiments, the filtration adsorption phosphorus removal bed (tower) is composed of a square, rectangular or circular tower body, which is a hollow column made of steel plate, stainless steel plate, aluminum plate, fiberglass or PE; the upper part of the filtration adsorption tower (barrel) is provided with a water inlet and a sewage outlet; the lower part of the filtration adsorption phosphorus removal bed (barrel) is provided with a clean water outlet, a regenerated liquid inlet, a sewage outlet and an aeration port.

[0083] In some embodiments, the filtration adsorption phosphorus removal system is an adsorption phosphorus removal system composed of 1 to N filtration adsorption beds; the filtration adsorption phosphorus removal system composed of 1 to N filtration adsorption beds is arranged in one, two, or three rows in sequence for adsorption; N is an integer from 2 to 12.

[0084] In some embodiments, the adsorption and phosphorus removal packing of the adsorption and phosphorus removal bed includes porous calcium-based expanded adsorption and phosphorus removal packing and ferric hydroxide expanded adsorption and phosphorus removal packing; the porous calcium-based expanded adsorption and phosphorus removal packing has a honeycomb porous structure, and is made by expanding, crushing, and sieving 10-15% by weight of activated diatomaceous earth as adsorbent, 25-38% by weight of gypsum powder as total phosphorus adsorbent, 25-30% by weight of cement as binder, 21.5-29.5% by weight of stone powder as aggregate, and 0.5% by weight of foaming agent. Its main technical indicators are: bulk density of 430-650 kg / m³. 3 Specific surface area ≥ 11.5 m² 2 / g, compressive strength ≥2.5MPa, porosity ≥75%, dry density ≤800kg / m³ 3 The water absorption rate is ≥35%, and the particle size range is 5-40mm. The expanded hydroxyl oxide adsorption phosphorus removal filler has a honeycomb-like porous structure. Its raw materials include 25-28% gypsum and 20-25% hydroxyl oxide as phosphorus adsorbent, 20-25% cement as cement binder, 21.5-26.5% stone powder as aggregate, and 0.5% foaming agent. The filler is expanded, crushed, and sieved. Its main technical indicators are: bulk density of 430-650 kg / m³. 3 Specific surface area ≥12.5m² 2 / g, compressive strength ≥3.5MPa, porosity ≥75%, dry density ≤800kg / m³ 3 Water absorption rate ≥35%, particle size range 3~40mm.

[0085] The preparation method of the above-mentioned expanded ferric hydroxide adsorption and phosphorus removal packing adopts the following steps:

[0086] S11: Ingredients: Mix 35-38% by weight of gypsum powder and 10-12% by weight of ferric hydroxide as phosphorus adsorbent, 20-35% by weight of cement as binder, and 14.5-17.5% by weight of stone powder as aggregate to obtain 600 parts of mixture (total weight is calculated as 1000 parts).

[0087] S12: Foaming: Add 0.5 parts by weight of anionic surfactant or cationic surfactant to 399.5 parts by weight of water and stir thoroughly to generate a large amount of foam;

[0088] S13: Pulping: Add the mixture obtained in S11 to the foaming liquid in S12, stir thoroughly, and prepare a slurry;

[0089] S14: Expansion molding: The slurry prepared by S11 is fed into a rectangular molding mold to be cross-linked and molded into a rectangular porous solid material;

[0090] S15: Crushing: The extruded and cross-linked solids are fed into a crusher for crushing;

[0091] S16: Sieving: The crushed material is sieved to obtain adsorption and phosphorus removal filter media with particle sizes of 2-5mm, 5-10mm, 10-20mm, and 10-20mm.

[0092] Example 1 describes the preparation of hydroxyl iron oxide expanded adsorption phosphorus removal packing.

[0093] S11: Ingredients: 35% by weight of 120-mesh gypsum powder and 12% by weight of 400-mesh ferric hydroxide as total phosphorus adsorbent, 35% by weight of cement as binder, and 17.5% by weight of 200-mesh stone powder as aggregate, mixed evenly to form 600 parts of mixture (total weight is calculated as 1000 parts).

[0094] S12: Foaming: Add 0.5 parts by weight of sodium dodecylbenzenesulfonate to 399.5 parts by weight of water and stir thoroughly to produce a large amount of foam;

[0095] S13: Pulping: Add the mixture obtained in S11 to the foaming liquid in S12, stir thoroughly, and prepare a slurry;

[0096] S14: Expansion molding: The slurry prepared by S14 is fed into a molding die to be cross-linked and molded into a porous solid material;

[0097] S15: Crushing: The extruded and cross-linked solids are fed into a crusher for crushing;

[0098] S16: Sieving: The crushed material is sieved to obtain porous iron-based expanded phosphorus adsorption packing with particle sizes of 2-5mm, 5-10mm, 10-20mm, and 20-40mm.

[0099] The preparation method of the above-mentioned porous calcium-based expanded adsorption phosphorus removal packing adopts the following steps:

[0100] S11: Ingredients: Mix 10-15% by weight of activated diatomaceous earth and 25-38% by weight of gypsum powder as total phosphorus adsorbent, 25-30% by weight of cement as binder, and 21.5-29.5% by weight of stone powder as aggregate to obtain 600 parts of mixture (total weight is calculated as 1000 parts).

[0101] S12: Foaming: Add 0.5 parts by weight of anionic surfactant or cationic surfactant to 399.5 parts by weight of water and stir thoroughly to generate a large amount of foam;

[0102] S13: Pulping: Add the mixture obtained in S11 to the foaming liquid in S12, stir thoroughly, and prepare a slurry;

[0103] S14: Expansion molding: The slurry prepared by S11 is fed into a rectangular molding mold to be cross-linked and molded into a rectangular porous solid material;

[0104] S15: Crushing: The extruded and cross-linked solids are fed into a crusher for crushing;

[0105] S16: Sieving: The crushed material is sieved to obtain adsorption and phosphorus removal filter media with particle sizes of 2-5mm, 5-10mm, 10-20mm, and 10-20mm.

[0106] Preparation Example 2: Preparation of porous calcium-based expanded adsorption and phosphorus removal packing.

[0107] S11: Ingredients: 38% by weight of 300-mesh gypsum powder as total phosphorus adsorbent, 15% by weight of 200-mesh activated diatomaceous earth as adsorbent, 25% by weight of cement as binder, and 21.5% by weight of 200-mesh stone powder as aggregate, mixed evenly to form 600 parts of mixture (total weight is calculated as 1000 parts).

[0108] S12: Foaming: Add 0.5 parts by weight of sodium dodecylbenzenesulfonate to 399.5 parts by weight of water and stir thoroughly to produce a large amount of foam;

[0109] S13: Pulping: Add the mixture obtained in S11 to the foaming liquid in S12, stir thoroughly, and prepare a slurry;

[0110] S14: Expansion molding: The slurry prepared by S14 is fed into a molding die to be cross-linked and molded into a porous solid material;

[0111] S15: Crushing: The extruded and cross-linked solids are fed into a crusher for crushing;

[0112] S16: Sieving: The crushed material is sieved to obtain porous calcium-based expanded phosphorus adsorption packing with particle sizes of 2-5mm, 5-10mm, 10-20mm, and 20-40mm.

[0113] In some embodiments, the ion exchange tower device in the ion exchange denitrification device includes anion exchange resin, which is used to adsorb anions such as nitrate and nitrite in the water to the anion exchange resin through ion exchange, thereby achieving denitrification of the water; the anion exchange resin is one of D401, D205 macroporous strong basic anion exchange resin, D890, LSI-106 weak basic macroporous anion exchange resin.

[0114] In some embodiments, the water filtration and adsorption phosphorus and nitrogen removal system includes at least a filter, an adsorption phosphorus removal tower, an ion exchange tower, and a nitrogen and phosphorus recovery device.

[0115] See Figure 8 A method for phosphorus and nitrogen removal and recovery of water bodies, characterized by using the aforementioned water body phosphorus and nitrogen removal and recovery system, and processing according to the following steps:

[0116] (1) Filtration: River and lake (reservoir) water containing 0.3-3 mg / L total phosphorus and 1-5 mg / L total nitrogen flows into the filtration device to filter out small solid particles and colloids in the water, and prevent small solid particles and colloids in the water from contaminating the phosphorus adsorption packing in the filtration adsorption tower.

[0117] (2) Phosphorus removal by adsorption: The river and lake (reservoir) water filtered in step (1) is introduced into the filtration adsorption tower (bucket), and the blower is turned on for aeration. The phosphorus-nitrogen-containing water flows out from top to bottom. The phosphate anions in the water are adsorbed by the phosphorus adsorbent, thereby removing the phosphate in the water. The phosphorus-removed water is then metered by a flow meter through the outlet of the filtration adsorption tower (bucket) and the outlet valve before entering the phosphorus-removed water pool or storage tank. The technical principle diagram is shown below. Figure 3 Reaction formula (adsorption reaction):

[0118] AO-OH+H2PO4 - =AO-HPO4 - +H₂O (A is a metal ion)

[0119] After filtration and adsorption for phosphorus removal, the effluent has COD≦20mg / L, ammonia nitrogen≦1mg / L, and total phosphorus≦0.1mg / L (for river water) or 0.025mg / L (for lake and reservoir water), with a phosphorus removal rate of 90-99.5%.

[0120] (3) Regeneration of the phosphorus filter adsorption packing: Monitor the total phosphorus concentration of the effluent regularly. When the total phosphorus concentration approaches the set value, first shut off the booster pump, then close the inlet valve and backwash liquid valve. Open the outlet valve of the backwash desorption device. Use the backwash pump to pump the alkaline washing regeneration liquid (extraction liquid) into the filter adsorption tower to the set level. Shut off the regeneration pump, aerate for 5 minutes, stop aeration and soak for 10 minutes, then aerate for another 5 minutes, stop aeration and soak for 10 minutes, repeating this process 4-6 times for a total backwash regeneration of 60... After approximately 90 minutes, the phosphate ions adsorbed in the adsorption packing are eluted, and the eluent regeneration solution is pumped into the reaction tank of the phosphorus recovery unit. After desorption, the adsorption is washed with water until neutral. After alkaline washing regeneration, the acid washing regeneration solution (elution solution) is pumped into the filter adsorption tower to the liquid level using a backwash pump. The backwash regeneration is carried out for 30-60 minutes to elute the calcium phosphate adsorbed in the adsorption packing. The eluent regeneration solution is pumped into the acid washing solution recovery tank. After acid washing regeneration, the adsorption packing is backwashed with water until neutral, thus completing the regeneration of the adsorption packing.

[0121] (4) Phosphorus recovery: The backwash desorption liquid is pumped into the reaction tank of the phosphorus recovery device, a phosphorus precipitant is added, and the reaction is stirred to make the phosphate ions in the recovery liquid react with calcium ions to form calcium phosphate precipitate. The backwash desorption liquid after the reaction is injected into the precipitation tank, the precipitate is separated, and dried to obtain the recovered calcium phosphate. The phosphorus precipitant is a clear saturated calcium hydroxide solution or a 5-25% calcium chloride solution.

[0122] Reaction formula (precipitation crystallization reaction):

[0123] 2PO4 3- +3Ca(OH)2=Ca3(PO4)2+6OH -

[0124] In summary, the reaction equations for adsorption, desorption, and phosphorus resource recovery are as follows:

[0125] Removal of phosphorus from wastewater (adsorption reaction)

[0126] AO-OH+H2PO4 - =AO-HPO4 - +H2O

[0127] Adsorbent regeneration (desorption reaction)

[0128] AO-HPO4 - +3OH - =AO-OH+PO4 3- +OH - +H2O

[0129] Phosphorus resource recovery (flocculation and crystallization reaction)

[0130] 2PO4 3- +3Ca(OH)2=Ca3(PO4)2+6OH -

[0131] The phosphorus precipitant is a clear saturated calcium hydroxide solution or a 5-25% calcium chloride solution.

[0132] The total phosphorus removal rate of the phosphorus filtration and adsorption device is greater than 90% after filtration and purification. Specifically: after water with a total phosphorus concentration greater than 1 mg / L is filtered and purified by the phosphorus filtration and adsorption device of the present invention, the total phosphorus concentration in the effluent is less than 0.2 mg / L; after water with a total phosphorus concentration of 0.5 to 1 mg / L is filtered and purified by the phosphorus filtration and adsorption device of the present invention, the total phosphorus concentration in the effluent is less than 0.1 mg / L; and after water with a total phosphorus concentration less than 0.5 mg / L is filtered and purified by the phosphorus filtration and adsorption device of the present invention, the total phosphorus concentration in the effluent is less than 0.025 mg / L.

[0133] (5) Anion exchange denitrification: The dephosphorized water that has undergone filtration and adsorption for phosphorus removal in step (2) and is stored in a dephosphorized water pool or tank is pumped into anion exchange tower. Nitrate and nitrite anions in the water are removed by anion exchange, thereby achieving total nitrogen removal from the water. The clear water after total nitrogen removal by anion exchange enters the denitrified water storage tank after being metered by a flow meter through the outlet and outlet valve of the ion exchange tower. After denitrification by anion exchange, the COD in the effluent is ≤20mg / L, ammonia nitrogen is ≤0.5mg / L, total nitrogen is ≤1mg / L, and total phosphorus is ≤0.1mg / L (river) or 0.025mg / L (lake / reservoir), with a total nitrogen removal rate of 80-99.0%.

[0134] (6) Regeneration of anion exchange resin: Monitor the total nitrogen concentration of the effluent from the ion exchange tower in a timely manner. When the total nitrogen concentration of the effluent approaches the set value, first turn off the booster pump, then close the inlet valve and the backwash liquid valve, and open the outlet valve of the backwash desorption device. Use the backwash pump to pump 5-10% sodium chloride regeneration liquid (elution liquid) into the ion exchange tower to the liquid level, turn off the regeneration pump, aerate for 5 minutes, stop aeration and soak for 15 minutes, aerate for another 5 minutes, stop aeration and soak for 15 minutes, repeat four to six times, and backwash regeneration for a total of 60-90 minutes to elute the nitrate adsorbed in the anion exchange resin. The eluent regeneration liquid is pumped into the reverse osmosis device for total nitrogen recovery, and separated into a 10-20% concentrate (high-concentration total nitrogen water) and an 80-90% dialysate through reverse osmosis filtration. The concentrate (high-concentration total nitrogen water) is pumped into the evaporation crystallization system to crystallize and recover nitrates.

[0135] (7) Reverse osmosis membrane concentration of anion exchange resin regenerated solution: The total nitrogen-rich regenerated solution generated from the regeneration of anion exchange resin in step (7) is pumped into the reverse osmosis concentration system, and the regenerated solution is separated into 10-20% concentrate and 80-90% dialysate through the reverse osmosis concentration system.

[0136] (8) Evaporation and crystallization of nitrates in the concentrate: The concentrate obtained by reverse osmosis concentration in step (8) is pumped into the heat exchanger of the evaporation and crystallization system, and then into the evaporator. After evaporation and concentration, it enters the crystallization tank and crystallizes out solid nitrates.

[0137] (9) Centrifugal separation: The concentrated liquid after evaporation and crystallization in step (9) is pumped into a centrifuge and separated by centrifugation to obtain nitrate solid and mother liquor. The nitrate solid can be used as artificial fertilizer.

[0138] The effluent indicators of the river water treated by the aforementioned water filtration and adsorption phosphorus and nitrogen removal system and method are as follows: COD≤20mg / L, BOD≤3mg / L, ammonia nitrogen≤1mg / L, total nitrogen≤1mg / L, total phosphorus≤0.2mg / L, SS≤10mg / L, color less than 5, and fecal coliform count less than 3 / L; the phosphorus removal rate is 90-99.5%, and other indicators of the effluent meet the corresponding water quality indicators of Class 3 surface water in Table 1 of the "Surface Water Environmental Quality Standard" (GB3838-2002).

[0139] After using the aforementioned water filtration and adsorption phosphorus and nitrogen removal system and method to remove phosphorus and nitrogen from lake and reservoir water, the effluent indicators of the lake and reservoir water are as follows: COD≤20mg / L, BOD≤3mg / L, ammonia nitrogen≤1mg / L, total nitrogen≤1mg / L, total phosphorus≤0.025mg / L, SS≤10mg / L, color less than 5, and fecal coliform count less than 3 / L; the phosphorus removal rate is 90-99.5%, and other indicators of the effluent meet the corresponding water quality indicators of Class 3 surface water in Table 1 of the "Surface Water Environmental Quality Standard" (GB3838-2002).

[0140] Example 1

[0141] A 10,000-ton / day river water phosphorus removal, nitrogen and phosphorus recovery system and method thereof.

[0142] See Table 1 for the water quality analysis of a certain river.

[0143] Table 1. Water Quality Indicators of Rivers

[0144]

[0145] As shown in Table 1, the river water meets the Class III water quality standards of the "Surface Water Environmental Quality Standard" (GB3838-2002) except for total phosphorus ≤0.5 mg / L, ammonia nitrogen ≤3.5 mg / L, and total nitrogen ≤3.6 mg / L. However, because the total phosphorus is 0.43 mg / L, ammonia nitrogen is 3.5 mg / L, and total nitrogen is 3.6 mg / L, the river water is classified as Class V or worse. To make it meet the Class III water quality standards of the "Surface Water Environmental Quality Standard" (GB3838-2002), it is necessary not only to reduce the total phosphorus to below 0.2 mg / L, but also to remove ammonia nitrogen and total nitrogen from the water body so that both ammonia nitrogen and total nitrogen are ≤1.0 mg / L. Therefore, the following phosphorus removal, denitrification, and nitrogen and phosphorus recovery scheme for rivers, lakes, and reservoirs is adopted.

[0146] A water filtration and adsorption phosphorus removal and nitrogen recovery system is characterized in that it consists of a water phosphorus removal and nitrogen recovery system arranged on the bank of a river.

[0147] See Figure 1 and Figure 8 A water filtration and adsorption phosphorus and nitrogen removal system includes: a filtration device (1), an adsorption phosphorus removal device (2), a phosphorus recovery device (3), an ion exchange nitrogen removal device (4), and a nitrogen recovery device (5), wherein:

[0148] The filter device 1 is used to filter and remove solid particles and colloids from the water to prevent solid particles and colloids from contaminating and clogging the filter media. The filter device is provided with an inlet, an outlet, a filter residue rinsing water inlet, and a filter residue rinsing water outlet. The inlet of the filter device is connected to the outlet of the booster pump, and the outlet of the filter device is connected to the inlet of the adsorption and phosphorus removal device.

[0149] The aforementioned filtration device is a multi-media filter.

[0150] See Figure 2 The phosphorus adsorption device 2 is used to filter and adsorb total phosphorus in water. The phosphorus adsorption device (2) consists of a phosphorus adsorption bed (2-1), a phosphorus adsorption bed inlet (2-2), an outlet (2-3), a support (2-4), an aeration pipe (2-5), a grid plate (2-6), a screen (2-7), and the phosphorus adsorption filter media (2-8) prepared in Preparation Example 1. The support (2-4) is used to support the grid plate. (2-6), the grid plate (2-6) is used to support the screen (2-7), the screen (2-7) has a pore size of 2-5mm, and is used to support the adsorption phosphorus removal filter material (2-8). The inlet (2-2) of the adsorption bed is connected to the outlet of the filter device via a four-way valve (311). The outlet (2-3) of the adsorption bed is connected to the inlet of the ion exchange tower (4-1) of the anion exchange denitrification device (4) via a four-way valve (313) and a valve.

[0151] See Figure 3The phosphorus recovery device (3) is used to recover phosphorus eluted from the phosphorus adsorption packing. The phosphorus recovery device consists of an adsorption bed, a regeneration system, a clean water backwashing system, and a phosphorus precipitation recovery device. The regeneration system of the phosphorus recovery device (3) consists of a regeneration liquid storage tank (318), an adsorption bed (2), and an eluent storage tank (322), used to elute the phosphorus adsorbed in the phosphorus removal filter media (2-8) and store it in the eluent storage tank (322). The outlet of the regeneration liquid storage tank (318) is connected to a dosing pump (314), the dosing pump (314) is connected to a valve (315), and (315) is connected to the inlet (2-2) of the phosphorus removal adsorption device (2) via a four-way valve. The water inlet (2-3) is connected to the four-way valve (313), one port of the four-way valve (313) is connected to the valve (320), and the valve (320) is connected to the eluent storage tank (322); the phosphorus recovery device (3) clean water backwashing system consists of a clean water storage tank (319), a water pump (316), a valve (317), a four-way valve (313), an adsorption phosphorus removal device (2), a valve (321), and an eluent storage tank (322); the phosphorus precipitation recovery device consists of a water pump (323), a valve (324), a reaction tank (325), a phosphorus precipitant dosing tank (326), a valve (327), a mixer (328), a dehydrator (329), a water pump (330), and an intermediate storage tank (331);

[0152] See Figure 4 The ion exchange device (4) is used to remove nitrate nitrogen and nitrite nitrogen from water by anion exchange; the ion exchange tower is composed of a tower body (4-1), an inlet (4-2), an outlet (4-3), a bottom column (4-10), a sieve plate support (4-8), a lower sieve plate (4-6), anion exchange resin (4-5), an upper sieve plate (4-4), and a tower cover plate (4-7). The bottom column (4-10) is used to support the tower body of the ion exchange device (4), and the sieve plate support (4-10) is used to support the tower body of the ion exchange device (4). 4-8) is used to support the lower sieve plate (4-6), which is used to support the anion exchange resin (4-5). The upper sieve plate (4-4) is used to enclose the anion exchange resin in the ion exchange tower. The dephosphorized water after adsorption and dephosphorization enters the ion exchange tower body (4-1) through the inlet (4-2) and reacts with the anion exchange resin in the tower body. The nitrate anions and nitrite anions in the water combine with the anion exchange resin and are adsorbed on the anion exchange resin.

[0153] See Figure 5The nitrogen recovery device (5) is used to recover total nitrogen, mainly nitrate nitrogen, eluted from the anion exchange resin. The nitrogen recovery device (5) consists of an ion exchange tower, an ion exchange regeneration system, a clean water backwashing system, a reverse osmosis total nitrogen concentration system for the ion exchange resin eluent, and a nitrate nitrogen evaporation and crystallization system. The ion exchange regeneration system consists of a regeneration liquid storage tank (521), a dosing pump (522), a valve (523), a four-way valve (512), an anion exchange resin tower (4), a water outlet (4-3), a four-way valve (519), a valve (527), and an eluent storage tank (528). The clean water backwashing system consists of a clean water storage tank (524), a clean water pump (525), a valve (526), ​​a four-way valve (519), an anion exchange resin tower (4), a drain tee (411), a drain valve (412), and an eluent storage tank (528).

[0154] See Figure 6 The reverse osmosis concentration system for the ion exchange resin eluent consists of a valve (611), a high-pressure pump (612), a reverse osmosis membrane module (613), a valve (614), a concentrate storage tank (615), a valve (616), and a dialysate storage tank (617).

[0155] See Figure 7 The nitrate nitrogen evaporation crystallization system is used to evaporate and crystallize total nitrogen, mainly nitrate nitrogen, in reverse osmosis concentrate. The nitrate nitrogen evaporation crystallization system consists of valve (711), pump (712), heat exchanger (713), valve (714), evaporator (715), valve (716), crystallization tank (717), centrifuge (719), condenser (720), valve (721), cooling water storage tank (722), and mother liquor storage tank (724).

[0156] The outlet of the total phosphorus filtration adsorption bed is connected to the inlet of the ion exchange tower of the anion exchange denitrification device, and the outlet of the ion exchange tower is connected to the outlet of the wastewater.

[0157] The anion exchange resin regeneration system is used to regenerate the anion exchange resin in the ion exchange tower, and consists of a regeneration washing solution storage tank, an ion exchange tower, and a regeneration solution recovery storage tank; the clean water backwashing system consists of a clean water storage tank, an ion exchange tower, and a cleaning solution recovery storage tank.

[0158] Specifically, the 10,000-ton / day filtration device is a multi-media filter, consisting of two... It consists of a circular media filter with a flow rate of 8 m / h.

[0159] Specifically, the 10,000-ton / day adsorption phosphorus removal bed (tower) consists of two rectangular tanks constructed of concrete, each measuring 20×13×2 meters. The upper part of the adsorption phosphorus removal bed is equipped with an inlet, and the lower part of the adsorption phosphorus removal bed is equipped with an outlet and an aeration port.

[0160] Specifically, the phosphorus adsorption filter material (2-8) is a porous calcium-based expanded adsorption phosphorus removal packing material, which is prepared according to Preparation Example 2, and its quantity is 1040m³. 3 The bulk density of the porous calcium-based expanded adsorption phosphorus removal packing is 430–650 kg / m³. 3 Specific surface area ≥ 11.5 m² 2 / g, compressive strength ≥2.5Mpa, porosity ≥75%, dry density ≤800kg / m3, water absorption ≥35%, particle size range 5~10mm;

[0161] Preferably, the ion exchange tower in the ion exchange denitrification device is an anion exchange resin exchange tower, used to adsorb anions such as nitrate and nitrite in the water onto the anion exchange resin through ion exchange, thereby achieving denitrification of the water; the anion exchange resin exchange tower consists of four... The anion exchange resin exchange tower has a flow rate of 4 m / h, and the anion exchange resin is D401 macroporous strong basic anion exchange resin.

[0162] See Figure 8 A method for phosphorus and nitrogen removal purification and nitrogen and phosphorus recovery of water, characterized in that the water is treated using the aforementioned water filtration and adsorption phosphorus and nitrogen removal system according to the following steps:

[0163] (1) Filtration: Filtration is used to remove small particulate solids and colloids from water to prevent them from clogging the filter adsorption tower; the oxidized wastewater flows into the precision filtration device to further filter and remove tiny solid particles from the wastewater, and the effluent after precision filtration flows into the filter adsorption phosphorus removal tower.

[0164] (2) Filtration and adsorption for phosphorus removal: The water filtered in step (1) is introduced into the filtration and adsorption phosphorus removal bed (bucket). The water flows out from top to bottom. The phosphate anions in the water are adsorbed by the phosphorus removal filter media (2-8) to remove phosphorus from the water. The clear water after phosphorus removal enters the ion exchange tower in step (3) through the outlet of the filtration and adsorption bed (tower).

[0165] The parameters of the influent and effluent water after filtration, adsorption and phosphorus removal are shown in Table 2.

[0166] Table 2. Influent and effluent indicators of river water after phosphorus adsorption and removal.

[0167]

[0168] Table 2 shows that after adsorption phosphorus removal treatment, the effluent has COD≦12mg / L, BOD≦1mg / L, ammonia nitrogen≦0.8mg / L, total nitrogen≦1.8mg / L, and total phosphorus≦0.08mg / L, with a phosphorus removal rate of 81.40%. Except for total nitrogen, other wastewater indicators meet the corresponding water quality indicators for Class III surface water in Table 1 of the "Surface Water Environmental Quality Standard" (GB3838-2002). Therefore, to ensure that the main water indicators meet the corresponding water quality indicators for Class III surface water in Table 1 of the "Surface Water Environmental Quality Standard" (GB3838-2002), anion exchange for total nitrogen removal is still necessary.

[0169] (3) Anion exchange denitrification: The effluent from the adsorption dephosphorization bed after step (2) is pumped into the ion exchange tower. Nitrate and nitrite anions in the water are removed by anion exchange, thereby achieving total nitrogen removal from the water. The anion exchange D401 removes nitrate and nitrite nitrogen. The clear water after total nitrogen removal is discharged into the natural water body through the outlet of the ion exchange tower.

[0170] After anion exchange denitrification, the effluent contained COD≦20mg / L, ammonia nitrogen≦0.2mg / L, total nitrogen≦0.8mg / L, and total phosphorus≦0.08mg / L (river channel), with a total nitrogen removal rate of 77.8%, as shown in Table 3.

[0171] Table 3. Influent and effluent indicators of river water after adsorption phosphorus removal and anion exchange dephosphorization.

[0172]

[0173] As shown in Table 3, after the river water, which was classified as Class V (inferior) and failed to meet the standards for ammonia nitrogen, total nitrogen, and total phosphorus, was purified by the nitrogen and phosphorus removal and nitrogen and phosphorus recovery system, all water quality indicators met the Class III water quality standard in Table 1 of the "Surface Water Environmental Quality Standard" (GB3838-2002).

[0174] (4) Regeneration of the phosphorus removal filter media: After the filter adsorption media reaches saturation, it is soaked in regeneration solution and backwashed to restore its filtration and phosphorus removal function. The total phosphorus concentration of the effluent is monitored in a timely manner. When the total phosphorus concentration of the effluent approaches the set value, the booster pump is turned off first, then the inlet valve and the backwash solution valve are closed. The outlet valve of the backwash regeneration system is opened, and the alkaline washing regeneration solution (extraction solution) is pumped into the filter adsorption phosphorus removal bed to the liquid level using the backwash pump. Backwashing and aeration are carried out for 60-90 minutes. Phosphate adsorbed in the adsorption and phosphorus removal packing is eluted, and the eluent is pumped into the eluent storage tank. After elution, it is washed with water until neutral. After alkaline regeneration, an acidic regeneration solution (elution solution) with pH 3-4 is pumped into the filter adsorption bed to the liquid level using a backwash pump. Acidic regeneration is carried out for 30-60 minutes to elute calcium phosphate adsorbed in the adsorption and phosphorus removal packing. The eluent is pumped into the acidic solution recovery tank. After acidic regeneration, it is backwashed with water until neutral, thus completing the regeneration of the adsorption and phosphorus removal packing.

[0175] The alkaline regeneration solution is a 0.5-1.0% sodium hydroxide solution with a pH of 12.7-13.

[0176] The acidic regeneration solution is a 0.25-0.5% citric acid solution with a pH of 3-4.

[0177] (5) Phosphorus recovery: Phosphorus recovery is used to separate and recover phosphorus eluted in the regenerated alkaline solution by generating calcium phosphate precipitate; the backwash desorption solution is pumped into the reaction tank of the phosphorus recovery device, a phosphorus precipitant is added, and the reaction is stirred to allow the phosphate ions in the recovery solution to react with calcium ions to generate calcium phosphate precipitate. The backwash desorption solution after the reaction is injected into the precipitation tank, the precipitate is separated, and dried to obtain the recovered calcium phosphate; the phosphorus precipitant is a clear saturated calcium hydroxide solution or a 5-25% calcium chloride solution.

[0178] The phosphorus precipitant is a clear, saturated calcium hydroxide solution.

[0179] The alkaline washing regeneration solution is a sodium hydroxide solution with a concentration of 0.75–1.0% (mass percentage) (pH ≥ 12.7).

[0180] The pickling regeneration solution is an acid solution of 0.25-0.3% (pH≤4).

[0181] After the alkaline washing regeneration solution is used, it is pumped into a phosphorus recovery device to recover phosphorus. The supernatant after phosphorus recovery is then stored in an alkaline washing solution recovery tank for reuse.

[0182] The pickling regeneration solution is recycled and stored in the pickling solution recycling tank after use.

[0183] (6) Regeneration of anion exchange resin: Monitor the total nitrogen concentration of the effluent from the ion exchange tower in a timely manner. When the total nitrogen concentration of the effluent approaches the set value, first turn off the booster pump, then close the inlet valve and the backwash liquid valve, and open the outlet valve of the backwash desorption device. Use the backwash pump to pump 5-10% sodium chloride regeneration liquid (elution liquid) into the ion exchange tower to the liquid level, turn off the regeneration pump, aerate for 5 minutes, stop aeration and soak for 15 minutes, aerate for another 5 minutes, stop aeration and soak for 15 minutes, repeat four to six times, and backwash regeneration for a total of 60-90 minutes to elute the nitrate adsorbed in the anion exchange resin. The eluent regeneration liquid is pumped into the reverse osmosis device for total nitrogen recovery, and separated into a 10-20% concentrate (high-concentration total nitrogen water) and an 80-90% dialysate through reverse osmosis filtration. The concentrate (high-concentration total nitrogen water) is pumped into the evaporation crystallization system to crystallize and recover nitrates.

[0184] (7) Concentration of anion exchange resin regenerated solution: The total nitrogen-rich regenerated solution generated from the regeneration of anion exchange resin in step (7) is pumped into the reverse osmosis concentration system, and the regenerated solution is separated into 10-20% concentrate and 80-90% dialysate through the reverse osmosis concentration system.

[0185] (8) Evaporation and crystallization of nitrates in the concentrate: The concentrate obtained by reverse osmosis concentration in step (8) is pumped into the heat exchanger of the evaporation and crystallization system, and then into the evaporator. After evaporation and concentration, it enters the crystallization tank and crystallizes out solid nitrates.

[0186] (9) Centrifugal separation: The concentrated liquid after evaporation and crystallization in step (9) is pumped into a centrifuge and separated by centrifugation to obtain nitrate solid and mother liquor.

[0187] During the phosphorus removal process, the river is divided into several sections, and each section is equipped with an extreme phosphorus and nitrogen removal purification system for the river water to be filtered, adsorbed, and purified.

[0188] Example 2

[0189] A 50,000-ton / day river water phosphorus removal, denitrification, and nitrogen and phosphorus recovery system and methods.

[0190] The water quality analysis of a certain river body with a capacity of 50,000 tons / day is shown in Table 4.

[0191] Table 4. Water Quality Indicators of Rivers

[0192]

[0193] As shown in Table 4, the river water meets the Class III water quality standards of the "Surface Water Environmental Quality Standard" (GB3838-2002) except for total phosphorus (0.61 mg / L) and total nitrogen (≤3.2 mg / L). However, because the total phosphorus is 0.61 mg / L and the total nitrogen is 3.2 mg / L, it is classified as Class V water, which is worse than Class V. To make it meet the Class III water quality standards of the "Surface Water Environmental Quality Standard" (GB3838-2002), not only does the total phosphorus need to be reduced to below 0.2 mg / L, but ammonia nitrogen and total nitrogen also need to be reduced to less than 1 mg / L. Therefore, the following water body phosphorus removal, denitrification, and nitrogen and phosphorus recovery scheme is adopted.

[0194] A water filtration and adsorption phosphorus removal and nitrogen recovery system is characterized in that it consists of a water phosphorus removal and nitrogen recovery system arranged on the bank of a river.

[0195] See Figure 1 and Figure 8 A water filtration and adsorption phosphorus and nitrogen removal system includes: a filtration device (1), an adsorption phosphorus removal device (2), a phosphorus recovery device (3), an ion exchange nitrogen removal device (4), and a nitrogen recovery device (5), wherein:

[0196] The filter device 1 is used to filter and remove solid particles and colloids from the water to prevent solid particles and colloids from contaminating and clogging the filter media. The filter device is provided with an inlet, an outlet, a filter residue rinsing water inlet, and a filter residue rinsing water outlet. The inlet of the filter device is connected to the outlet of the booster pump, and the outlet of the filter device is connected to the inlet of the adsorption and phosphorus removal device.

[0197] The filtration device is a rotary microfiltration system.

[0198] See Figure 2 The phosphorus adsorption device 2 is used to filter and adsorb total phosphorus in water. The phosphorus adsorption device (2) consists of a phosphorus adsorption bed (2-1), a phosphorus adsorption bed inlet (2-2), an outlet (2-3), a support (2-4), an aeration pipe (2-5), a grid plate (2-6), a screen (2-7), and the phosphorus adsorption filter media (2-8) prepared in Preparation Example 1. The support (2-4) is used to support the grid plate. (2-6), the grid plate (2-6) is used to support the screen (2-7), the screen (2-7) has a pore size of 2-5mm, and is used to support the adsorption phosphorus removal filter material (2-8). The inlet (2-2) of the adsorption bed is connected to the outlet of the filter device via a four-way valve (311). The outlet (2-3) of the adsorption bed is connected to the inlet of the ion exchange tower (4-1) of the anion exchange denitrification device (4) via a four-way valve (313) and a valve.

[0199] See Figure 3 The phosphorus recovery device (3) is used to recover phosphorus eluted from the phosphorus adsorption packing. The phosphorus recovery device consists of an adsorption bed, a regeneration system, a clean water backwashing system, and a phosphorus precipitation recovery device. The regeneration system of the phosphorus recovery device (3) consists of a regeneration liquid storage tank (318), an adsorption bed (2), and an eluent storage tank (322), used to elute the phosphorus adsorbed in the phosphorus removal filter media (2-8) and store it in the eluent storage tank (322). The outlet of the regeneration liquid storage tank (318) is connected to a dosing pump (314), the dosing pump (314) is connected to a valve (315), and (315) is connected to the inlet (2-2) of the phosphorus removal adsorption device (2) via a four-way valve. The water inlet (2-3) is connected to the four-way valve (313), one port of the four-way valve (313) is connected to the valve (320), and the valve (320) is connected to the eluent storage tank (322); the phosphorus recovery device (3) clean water backwashing system consists of a clean water storage tank (319), a water pump (316), a valve (317), a four-way valve (313), an adsorption phosphorus removal device (2), a valve (321), and an eluent storage tank (322); the phosphorus precipitation recovery device consists of a water pump (323), a valve (324), a reaction tank (325), a phosphorus precipitant dosing tank (326), a valve (327), a mixer (328), a dehydrator (329), a water pump (330), and an intermediate storage tank (331);

[0200] See Figure 4 The ion exchange device (4) is used to remove nitrate nitrogen and nitrite nitrogen from water by anion exchange; the ion exchange tower is composed of a tower body (4-1), an inlet (4-2), an outlet (4-3), a bottom column (4-10), a sieve plate support (4-8), a lower sieve plate (4-6), anion exchange resin (4-5), an upper sieve plate (4-4), and a tower cover plate (4-7). The bottom column (4-10) is used to support the tower body of the ion exchange device (4), and the sieve plate support (4-10) is used to support the tower body of the ion exchange device (4). 4-8) is used to support the lower sieve plate (4-6), which is used to support the anion exchange resin (4-5). The upper sieve plate (4-4) is used to enclose the anion exchange resin in the ion exchange tower. The dephosphorized water after adsorption and dephosphorization enters the ion exchange tower body (4-1) through the inlet (4-2) and reacts with the anion exchange resin in the tower body. The nitrate anions and nitrite anions in the water combine with the anion exchange resin and are adsorbed on the anion exchange resin.

[0201] See Figure 5The nitrogen recovery device (5) is used to recover total nitrogen, mainly nitrate nitrogen, eluted from the anion exchange resin. The nitrogen recovery device (5) consists of an ion exchange tower, an ion exchange regeneration system, a clean water backwashing system, a reverse osmosis total nitrogen concentration system for the ion exchange resin eluent, and a nitrate nitrogen evaporation and crystallization system. The ion exchange regeneration system consists of a regeneration liquid storage tank (521), a dosing pump (522), a valve (523), a four-way valve (512), an anion exchange resin tower (4), a water outlet (4-3), a four-way valve (519), a valve (527), and an eluent storage tank (528). The clean water backwashing system consists of a clean water storage tank (524), a clean water pump (525), a valve (526), ​​a four-way valve (519), an anion exchange resin tower (4), a drain tee (411), a drain valve (412), and an eluent storage tank (528).

[0202] See Figure 6 The reverse osmosis concentration system for the ion exchange resin eluent consists of a valve (611), a high-pressure pump (612), a reverse osmosis membrane module (613), a valve (614), a concentrate storage tank (615), a valve (616), and a dialysate storage tank (617).

[0203] See Figure 7 The nitrate nitrogen evaporation crystallization system is used to evaporate and crystallize total nitrogen, mainly nitrate nitrogen, in reverse osmosis concentrate. The nitrate nitrogen evaporation crystallization system consists of valve (711), pump (712), heat exchanger (713), valve (714), evaporator (715), valve (716), crystallization tank (717), centrifuge (719), condenser (720), valve (721), cooling water storage tank (722), and mother liquor storage tank (724).

[0204] The outlet of the total phosphorus filtration adsorption bed is connected to the inlet of the ion exchange tower of the anion exchange denitrification device, and the outlet of the ion exchange tower is connected to the outlet of the wastewater.

[0205] The anion exchange resin regeneration system is used to regenerate the anion exchange resin in the ion exchange tower, and consists of a regeneration washing solution storage tank, an ion exchange tower, and a regeneration solution recovery storage tank; the clean water backwashing system consists of a clean water storage tank, an ion exchange tower, and a cleaning solution recovery storage tank.

[0206] Specifically, the 50,000-ton / day filtration device is a rotary microfiltration system, consisting of three 30,000-ton / day (2 in use and 1 in standby) submerged rotary microfiltration units with a flow rate of 8 m / h.

[0207] Specifically, since the total phosphorus concentration in the water is 0.61 mg / L, less than 1.00 mg / L, the designed retention time is 2.5 hours. The 50,000 tons / day adsorption phosphorus removal bed consists of two rectangular concrete tanks, each 54 × 17.5 × 3 meters in size, with a flow rate of 8 m / h. The upper part of the adsorption phosphorus removal bed has an inlet; the lower part of the adsorption phosphorus removal bed has an outlet and an aeration port.

[0208] Specifically, the phosphorus adsorption filter material (2-8) is a honeycomb-like porous packing material made of expanded iron hydroxyl oxide for phosphorus adsorption, prepared according to Preparation Example 1. Its main technical indicators are: bulk density of 430-650 kg / m³. 3 Specific surface area ≥12.5m² 2 / g, compressive strength ≥3.5MPa, porosity ≥75%, dry density ≤800kg / m³ 3 Water absorption rate ≥35%, particle size range 10~20mm.

[0209] Preferably, the anion exchange denitrification device is an anion exchange resin exchange tower, used to adsorb anions such as nitrate and nitrite in the water onto the anion exchange resin through ion exchange, thereby achieving denitrification of the water; the anion exchange resin exchange tower has 6 units. The anion exchange resin exchange tower (5 in operation, 1 in standby) has a flow rate of 8 m / h, and the anion exchange resin is LSI-106 weakly basic macroporous anion exchange resin.

[0210] See Figure 8 A method for phosphorus and nitrogen removal purification and nitrogen and phosphorus recovery of water, characterized in that the water is treated using the aforementioned water filtration and adsorption phosphorus and nitrogen removal system according to the following steps:

[0211] (1) Filtration: Filtration is used to remove small particulate solids and colloids from water to prevent them from clogging the filter adsorption tower; the oxidized wastewater flows into the precision filtration device to further filter and remove tiny solid particles from the wastewater, and the effluent after precision filtration flows into the filter adsorption phosphorus removal tower.

[0212] (2) Filtration and adsorption for phosphorus removal: The water filtered in step (1) is introduced into the filtration and adsorption phosphorus removal bed (bucket). The water flows out from top to bottom. The phosphate anions in the water are adsorbed by the phosphorus removal filter media (2-8) to remove phosphorus from the water. The clear water after phosphorus removal enters the ion exchange tower in step (3) through the outlet of the filtration and adsorption bed (tower).

[0213] The parameters of the influent and effluent water after filtration, adsorption and phosphorus removal are shown in Table 5.

[0214] Table 5. Influent and effluent indicators of river water after phosphorus adsorption and removal.

[0215]

[0216] Table 2 shows that after adsorption phosphorus removal treatment, the effluent has COD≦17mg / L, BOD≦3mg / L, ammonia nitrogen≦0.8mg / L, total nitrogen≦2.9mg / L, and total phosphorus≦0.08mg / L, with a phosphorus removal rate of 86.89%. Except for total nitrogen, other wastewater indicators meet the corresponding water quality indicators for Class III surface water in Table 1 of the "Surface Water Environmental Quality Standard" (GB3838-2002). Therefore, to ensure that the main water body indicators meet the corresponding water quality indicators for Class III surface water in Table 1 of the "Surface Water Environmental Quality Standard" (GB3838-2002), anion exchange for total nitrogen removal is still necessary.

[0217] (4) Anion exchange denitrification: The effluent from the adsorption dephosphorization bed after step (2) is pumped into the ion exchange tower. Nitrate and nitrite anions in the water are removed by anion exchange, thereby achieving total nitrogen removal from the water. The clear water after total nitrogen removal is discharged into the natural water body through the outlet of the ion exchange tower.

[0218] After anion exchange denitrification, the effluent contained COD≦20mg / L, ammonia nitrogen≦0.2mg / L, total nitrogen≦0.9mg / L, and total phosphorus≦0.08mg / L (river channel), with a total nitrogen removal rate of 71.88%, as shown in Table 6.

[0219] Table 6. Influent and effluent indicators of river water after adsorption phosphorus removal and anion exchange dephosphorization.

[0220]

[0221] As shown in Table 6, after the river water, which was classified as Class V (inferior) and failed to meet the standards for ammonia nitrogen, total nitrogen, and total phosphorus, was purified by the nitrogen and phosphorus removal and nitrogen and phosphorus recovery system, all water quality indicators met the Class III water quality standard in Table 1 of the "Surface Water Environmental Quality Standard" (GB3838-2002).

[0222] (4) Regeneration of the phosphorus removal filter media: After the filter adsorption media reaches saturation, it is soaked in regeneration solution and backwashed to restore its filtration and phosphorus removal function. The total phosphorus concentration of the effluent is monitored in a timely manner. When the total phosphorus concentration of the effluent approaches the set value, the booster pump is turned off first, then the inlet valve and the backwash solution valve are closed. The outlet valve of the backwash regeneration system is opened, and the alkaline washing regeneration solution (extraction solution) is pumped into the filter adsorption phosphorus removal bed to the liquid level using the backwash pump. Backwashing and aeration are carried out for 60-90 minutes. Phosphate adsorbed in the adsorption and phosphorus removal packing is eluted, and the eluent is pumped into the eluent storage tank. After elution, it is washed with water until neutral. After alkaline regeneration, an acidic regeneration solution (elution solution) with pH 3-4 is pumped into the filter adsorption bed to the liquid level using a backwash pump. Acidic regeneration is carried out for 30-60 minutes to elute calcium phosphate adsorbed in the adsorption and phosphorus removal packing. The eluent is pumped into the acidic solution recovery tank. After acidic regeneration, it is backwashed with water until neutral, thus completing the regeneration of the adsorption and phosphorus removal packing.

[0223] The alkaline regeneration solution is a 0.5-1.0% sodium hydroxide solution with a pH of 12.7-13.

[0224] The acidic regeneration solution is a 0.25-0.5% citric acid solution with a pH of 3-4.

[0225] (5) Phosphorus recovery: Phosphorus recovery is used to separate and recover phosphorus eluted in the regenerated alkaline solution by generating calcium phosphate precipitate; the backwash desorption solution is pumped into the reaction tank of the phosphorus recovery device, a phosphorus precipitant is added, and the reaction is stirred to allow the phosphate ions in the recovery solution to react with calcium ions to generate calcium phosphate precipitate. The backwash desorption solution after the reaction is injected into the precipitation tank, the precipitate is separated, and dried to obtain the recovered calcium phosphate; the phosphorus precipitant is a clear saturated calcium hydroxide solution or a 5-25% calcium chloride solution.

[0226] The phosphorus precipitant is a clear, saturated calcium hydroxide solution.

[0227] The alkaline washing regeneration solution is a sodium hydroxide solution with a concentration of 0.75–1.0% (mass percentage) (pH ≥ 12.7).

[0228] The pickling regeneration solution is an acid solution of 0.25-0.3% (pH≤4).

[0229] After the alkaline washing regeneration solution is used, it is pumped into a phosphorus recovery device to recover phosphorus. The supernatant after phosphorus recovery is then stored in an alkaline washing solution recovery tank for reuse.

[0230] The pickling regeneration solution is recycled and stored in the pickling solution recycling tank after use.

[0231] (6) Regeneration of anion exchange resin: Monitor the total nitrogen concentration of the effluent from the ion exchange tower in a timely manner. When the total nitrogen concentration of the effluent approaches the set value, first turn off the booster pump, then close the inlet valve and the backwash liquid valve, and open the outlet valve of the backwash desorption device. Use the backwash pump to pump 5-10% sodium chloride regeneration liquid (elution liquid) into the ion exchange tower to the liquid level, turn off the regeneration pump, aerate for 5 minutes, stop aeration and soak for 15 minutes, aerate for another 5 minutes, stop aeration and soak for 15 minutes, repeat four to six times, and backwash regeneration for a total of 60-90 minutes to elute the nitrate adsorbed in the anion exchange resin. The eluent regeneration liquid is pumped into the reverse osmosis device for total nitrogen recovery, and separated into a 10-20% concentrate (high-concentration total nitrogen water) and an 80-90% dialysate through reverse osmosis filtration. The concentrate (high-concentration total nitrogen water) is pumped into the evaporation crystallization system to crystallize and recover nitrates.

[0232] (7) Concentration of anion exchange resin regenerated solution: The total nitrogen-rich regenerated solution generated from the regeneration of anion exchange resin in step (7) is pumped into the reverse osmosis concentration system, and the regenerated solution is separated into 10-20% concentrate and 80-90% dialysate through the reverse osmosis concentration system.

[0233] (8) Evaporation and crystallization of nitrates in the concentrate: The concentrate obtained by reverse osmosis concentration in step (8) is pumped into the heat exchanger of the evaporation and crystallization system, and then into the evaporator. After evaporation and concentration, it enters the crystallization tank and crystallizes out solid nitrates.

[0234] (9) Centrifugal separation: The concentrated liquid after evaporation and crystallization in step (9) is pumped into a centrifuge and separated by centrifugation to obtain nitrate solid and mother liquor.

[0235] During the phosphorus removal process, the river is divided into several sections, and each section is equipped with an extreme phosphorus and nitrogen removal purification system for the river water to be filtered, adsorbed, and purified.

[0236] Example 3

[0237] A 10,000-ton / day lake water phosphorus removal, nitrogen and phosphorus recovery system and method thereof.

[0238] The water quality analysis of a certain lake is shown in Table 7.

[0239] Table 7. Water Quality Indicators of a Certain Lake

[0240]

[0241] As shown in Table 7, the lake water meets the Class III water quality standards of the "Surface Water Environmental Quality Standard" (GB3838-2002) except for total phosphorus (1.87 mg / L) and total nitrogen (≤3.1 mg / L). However, because the total phosphorus is 1.87 mg / L and the ammonia nitrogen is 3.1 mg / L, it is classified as Class V (worst) river water. To improve the water quality to meet the Class III standards of the "Surface Water Environmental Quality Standard" (GB3838-2002), it is necessary not only to reduce the total phosphorus to below 0.05 mg / L, but also to remove the total nitrogen to ≤1.0 mg / L. For this purpose, the usual water environment management solution is to use artificial wetlands and ecological floating beds for ecological management. Located in a southern city, this river, according to relevant technical requirements such as the "Technical Guidelines for Water Purification in Artificial Wetlands," the "Technical Guidelines for Restoration and Reconstruction of Natural Wetlands," and the "Technical Guidelines for Protection and Restoration of River and Lake Ecological Buffer Zones," typically involves restoring and reconstructing the riparian wetlands in this section of the river to create suitable riparian habitat conditions, restore aquatic vegetation, and meet its main ecological service functions. According to the "Technical Guidelines for Water Purification in Artificial Wetlands," the main design parameters of artificial wetlands should be calculated based on climate zones and combined with experience in the same region. The pollutant reduction load (NA) is taken as: COD: 15 g / (m³). 2 ·d), ammonia nitrogen: 4g / (m 2 ·d), Total phosphorus: 0.25g / (m 2 ·d), and in conjunction with the inflow and outflow targets, the wetland area of ​​a lake with 10,000 tons / day is calculated as follows: (1) Based on the total phosphorus removal: 18,200g, [i.e. (1.87-0.05)×10,000], then the wetland area required to remove total phosphorus is 72,800m². 2 To ensure that the effluent meets the standards, the wetland area for total phosphorus removal should be 72,800 m². 2 Therefore, it is evident that using artificial wetlands would not only require a large amount of land to establish them, but also fail to guarantee the quality of the effluent. Furthermore, the area surrounding the lake is mostly basic farmland, with no suitable land available for constructing artificial wetlands. Therefore, the design unit found a non-agricultural land area of ​​approximately 1500 square meters on the lakeshore and adopted a bypass water intake method, employing the following water body phosphorus removal, denitrification, and nitrogen and phosphorus recovery scheme.

[0242] A water filtration and adsorption system for phosphorus and nitrogen removal and recovery is characterized in that it consists of a water phosphorus and nitrogen removal and recovery system arranged on the shore of a lake.

[0243] See Figure 1 and Figure 8 A water filtration and adsorption phosphorus and nitrogen removal system includes: a filtration device (1), an adsorption phosphorus removal device (2), a phosphorus recovery device (3), an ion exchange nitrogen removal device (4), and a nitrogen recovery device (5), wherein:

[0244] The filter device 1 is used to filter and remove solid particles and colloids from the water to prevent solid particles and colloids from contaminating and clogging the filter media. The filter device is provided with an inlet, an outlet, a filter residue rinsing water inlet, and a filter residue rinsing water outlet. The inlet of the filter device is connected to the outlet of the booster pump, and the outlet of the filter device is connected to the inlet of the adsorption and phosphorus removal device.

[0245] The filtration device is a fiber disc filter.

[0246] See Figure 2 The phosphorus removal device 2 is used to filter and remove total phosphorus from water by the phosphorus removal device (2). The phosphorus removal device (2) consists of a phosphorus adsorption bed (2-1), a phosphorus adsorption bed inlet (2-2), an outlet (2-3), a support (2-4), an aeration pipe (2-5), a grid plate (2-6), a screen (2-7), and the phosphorus removal filter media (2-8) prepared in Preparation Example 2. The support (2-4) is used to support the grid plate. (2-6), the grid plate (2-6) is used to support the screen (2-7), the screen (2-7) has a pore size of 2-5mm, and is used to support the adsorption phosphorus removal filter material (2-8). The inlet (2-2) of the adsorption bed is connected to the outlet of the filter device via a four-way valve (311). The outlet (2-3) of the adsorption bed is connected to the inlet of the ion exchange tower (4-1) of the anion exchange denitrification device (4) via a four-way valve (313) and a valve.

[0247] See Figure 3The phosphorus recovery device (3) is used to recover phosphorus eluted from the phosphorus adsorption packing. The phosphorus recovery device consists of an adsorption bed, a regeneration system, a clean water backwashing system, and a phosphorus precipitation recovery device. The regeneration system of the phosphorus recovery device (3) consists of a regeneration liquid storage tank (318), an adsorption bed (2), and an eluent storage tank (322), used to elute the phosphorus adsorbed in the phosphorus removal filter media (2-8) and store it in the eluent storage tank (322). The outlet of the regeneration liquid storage tank (318) is connected to a dosing pump (314), the dosing pump (314) is connected to a valve (315), and (315) is connected to the inlet (2-2) of the phosphorus removal adsorption device (2) via a four-way valve. The water inlet (2-3) is connected to the four-way valve (313), one port of the four-way valve (313) is connected to the valve (320), and the valve (320) is connected to the eluent storage tank (322); the phosphorus recovery device (3) clean water backwashing system consists of a clean water storage tank (319), a water pump (316), a valve (317), a four-way valve (313), an adsorption phosphorus removal device (2), a valve (321), and an eluent storage tank (322); the phosphorus precipitation recovery device consists of a water pump (323), a valve (324), a reaction tank (325), a phosphorus precipitant dosing tank (326), a valve (327), a mixer (328), a dehydrator (329), a water pump (330), and an intermediate storage tank (331);

[0248] See Figure 4 The ion exchange device (4) is used to remove nitrate nitrogen and nitrite nitrogen from water by anion exchange; the ion exchange tower is composed of a tower body (4-1), an inlet (4-2), an outlet (4-3), a bottom column (4-10), a sieve plate support (4-8), a lower sieve plate (4-6), anion exchange resin (4-5), an upper sieve plate (4-4), and a tower cover plate (4-7). The bottom column (4-10) is used to support the tower body of the ion exchange device (4), and the sieve plate support (4-10) is used to support the tower body of the ion exchange device (4). 4-8) is used to support the lower sieve plate (4-6), which is used to support the anion exchange resin (4-5). The upper sieve plate (4-4) is used to enclose the anion exchange resin in the ion exchange tower. The dephosphorized water after adsorption and dephosphorization enters the ion exchange tower body (4-1) through the inlet (4-2) and reacts with the anion exchange resin in the tower body. The nitrate anions and nitrite anions in the water combine with the anion exchange resin and are adsorbed on the anion exchange resin.

[0249] See Figure 5The nitrogen recovery device (5) is used to recover total nitrogen, mainly nitrate nitrogen, eluted from the anion exchange resin. The nitrogen recovery device (5) consists of an ion exchange tower, an ion exchange regeneration system, a clean water backwashing system, a reverse osmosis total nitrogen concentration system for the ion exchange resin eluent, and a nitrate nitrogen evaporation and crystallization system. The ion exchange regeneration system consists of a regeneration liquid storage tank (521), a dosing pump (522), a valve (523), a four-way valve (512), an anion exchange resin tower (4), a water outlet (4-3), a four-way valve (519), a valve (527), and an eluent storage tank (528). The clean water backwashing system consists of a clean water storage tank (524), a clean water pump (525), a valve (526), ​​a four-way valve (519), an anion exchange resin tower (4), a drain tee (411), a drain valve (412), and an eluent storage tank (528).

[0250] See Figure 6 The reverse osmosis concentration system for the ion exchange resin eluent consists of a valve (611), a high-pressure pump (612), a reverse osmosis membrane module (613), a valve (614), a concentrate storage tank (615), a valve (616), and a dialysate storage tank (617).

[0251] See Figure 7 The nitrate nitrogen evaporation crystallization system is used to evaporate and crystallize total nitrogen, mainly nitrate nitrogen, in reverse osmosis concentrate. The nitrate nitrogen evaporation crystallization system consists of valve (711), pump (712), heat exchanger (713), valve (714), evaporator (715), valve (716), crystallization tank (717), centrifuge (719), condenser (720), valve (721), cooling water storage tank (722), and mother liquor storage tank (724).

[0252] The outlet of the total phosphorus filtration adsorption bed is connected to the inlet of the ion exchange tower of the anion exchange denitrification device, and the outlet of the ion exchange tower is connected to the outlet of the wastewater.

[0253] The anion exchange resin regeneration system is used to regenerate the anion exchange resin in the ion exchange tower, and consists of a regeneration washing solution storage tank, an ion exchange tower, and a regeneration solution recovery storage tank; the clean water backwashing system consists of a clean water storage tank, an ion exchange tower, and a cleaning solution recovery storage tank.

[0254] Specifically, the 10,000-ton / day filtration device is a fiber disc filter, consisting of two... It consists of a fiber disc filter.

[0255] Specifically, due to the high total phosphorus concentration of 1.87 mg / L in the lake, the retention time is designed to be 3 hours to ensure the quality of the effluent. The 10,000 tons / day adsorption phosphorus removal bed (tower) consists of two rectangular concrete tanks of 20×16×2 meters each. The upper part of the adsorption phosphorus removal bed is equipped with an inlet, and the lower part of the adsorption phosphorus removal bed is equipped with an outlet and an aeration port. The flow rate is 15 m / h.

[0256] Specifically, the adsorption phosphorus removal filter material (2-8) is the porous calcium-based expanded adsorption phosphorus removal packing prepared in Preparation Example 2, with a quantity of 1250m. 3 The porous calcium-based expanded adsorption phosphorus removal packing has a bulk density of 430–650 kg / m³ and a specific surface area ≥11.5 m². 2 / g, compressive strength ≥2.5Mpa, porosity ≥75%, dry density ≤800kg / m3, water absorption ≥35%, particle size range 5~10mm;

[0257] Preferably, the ion exchange tower in the ion exchange denitrification device is an anion exchange resin exchange tower, used to adsorb anions such as nitrate and nitrite in the water onto the anion exchange resin through ion exchange, thereby achieving denitrification of the water; the anion exchange resin exchange tower consists of four... The anion exchange resin exchange tower has a flow rate of 4 m / h, and the anion exchange resin is D205 macroporous strong basic anion exchange resin.

[0258] See Figure 8 A method for phosphorus and nitrogen removal purification and nitrogen and phosphorus recovery of water, characterized in that the water is treated using the aforementioned water filtration and adsorption phosphorus and nitrogen removal system according to the following steps:

[0259] (1) Filtration: Filtration is used to remove small particulate solids and colloids from water to prevent them from clogging the filter adsorption tower; the oxidized wastewater flows into the precision filtration device to further filter and remove tiny solid particles from the wastewater, and the effluent after precision filtration flows into the filter adsorption phosphorus removal tower.

[0260] (2) Filtration and adsorption for phosphorus removal: The water filtered in step (1) is introduced into the filtration and adsorption phosphorus removal bed (bucket). The water flows out from top to bottom. The phosphate anions in the water are adsorbed by the phosphorus removal filter media (2-8) to remove phosphorus from the water. The clear water after phosphorus removal enters the ion exchange tower in step (3) through the outlet of the filtration and adsorption bed (tower).

[0261] The parameters of the influent and effluent water after filtration, adsorption and phosphorus removal are shown in Table 8.

[0262] Table 8. Influent and effluent indicators of lake water after phosphorus adsorption and removal.

[0263]

[0264] Table 8 shows that after adsorption phosphorus removal treatment, the effluent from the lake has COD≦17mg / L, BOD≦4mg / L, ammonia nitrogen≦0.8mg / L, total nitrogen≦2.9mg / L, and total phosphorus≦0.023mg / L, with a phosphorus removal rate of 93.04%. Except for total nitrogen, other wastewater indicators meet the corresponding water quality indicators for Class III surface water in Table 1 of the "Surface Water Environmental Quality Standard" (GB3838-2002). Therefore, to ensure that the main water indicators meet the corresponding water quality indicators for Class III surface water in Table 1 of the "Surface Water Environmental Quality Standard" (GB3838-2002), anion exchange for total nitrogen removal is still necessary.

[0265] (5) Anion exchange denitrification: The effluent from the adsorption dephosphorization bed after step (2) is pumped into the ion exchange tower. Nitrate and nitrite anions in the water are removed by anion exchange, thereby achieving total nitrogen removal from the water. The nitrate and nitrite nitrogen are removed by D205 macroporous strong basic anion exchange resin. The clear water after total nitrogen removal is discharged into natural water bodies through the outlet of the ion exchange tower.

[0266] After anion exchange denitrification, the effluent contained COD≦16mg / L, ammonia nitrogen≦0.8mg / L, total nitrogen≦0.9mg / L, and total phosphorus≦0.11mg / L (river channel), with a total nitrogen removal rate of 77.8%, as shown in Table 9.

[0267] Table 9. Influent and effluent indicators of river water after adsorption phosphorus removal and anion exchange dephosphorization.

[0268]

[0269] As shown in Table 9, after purification by the nitrogen and phosphorus removal and nitrogen and phosphorus recovery system, the Class V lake water, which was below the standard for ammonia nitrogen, total nitrogen and total phosphorus, met the Class III water quality standard in Table 1 of the "Surface Water Environmental Quality Standard" (GB3838-2002).

[0270] (4) Regeneration of the phosphorus removal filter media: After the filter adsorption media reaches saturation, it is soaked in regeneration solution and backwashed to restore its filtration and phosphorus removal function. The total phosphorus concentration of the effluent is monitored in a timely manner. When the total phosphorus concentration of the effluent approaches the set value, the booster pump is turned off first, then the inlet valve and the backwash solution valve are closed. The outlet valve of the backwash regeneration system is opened, and the alkaline washing regeneration solution (extraction solution) is pumped into the filter adsorption phosphorus removal bed to the liquid level using the backwash pump. Backwashing and aeration are carried out for 60-90 minutes. Phosphate adsorbed in the adsorption and phosphorus removal packing is eluted, and the eluent is pumped into the eluent storage tank. After elution, it is washed with water until neutral. After alkaline regeneration, an acidic regeneration solution (elution solution) with pH 3-4 is pumped into the filter adsorption bed to the liquid level using a backwash pump. Acidic regeneration is carried out for 30-60 minutes to elute calcium phosphate adsorbed in the adsorption and phosphorus removal packing. The eluent is pumped into the acidic solution recovery tank. After acidic regeneration, it is backwashed with water until neutral, thus completing the regeneration of the adsorption and phosphorus removal packing.

[0271] The alkaline regeneration solution is a 0.5-1.0% sodium hydroxide solution with a pH of 12.7-13.

[0272] The acidic regeneration solution is a 0.25-0.5% citric acid solution with a pH of 3-4.

[0273] (5) Phosphorus recovery: Phosphorus recovery is used to separate and recover phosphorus eluted in the regenerated alkaline solution by generating calcium phosphate precipitate; the backwash desorption solution is pumped into the reaction tank of the phosphorus recovery device, a phosphorus precipitant is added, and the reaction is stirred to allow the phosphate ions in the recovery solution to react with calcium ions to generate calcium phosphate precipitate. The backwash desorption solution after the reaction is injected into the precipitation tank, the precipitate is separated, and dried to obtain the recovered calcium phosphate; the phosphorus precipitant is a clear saturated calcium hydroxide solution or a 5-25% calcium chloride solution.

[0274] The phosphorus precipitant is a clear, saturated calcium hydroxide solution.

[0275] The alkaline washing regeneration solution is a sodium hydroxide solution with a concentration of 0.75–1.0% (mass percentage) (pH ≥ 12.7).

[0276] The pickling regeneration solution is an acid solution of 0.25-0.3% (pH≤4).

[0277] After the alkaline washing regeneration solution is used, it is pumped into a phosphorus recovery device to recover phosphorus. The supernatant after phosphorus recovery is then stored in an alkaline washing solution recovery tank for reuse.

[0278] The pickling regeneration solution is recycled and stored in the pickling solution recycling tank after use.

[0279] (6) Regeneration of anion exchange resin: Monitor the total nitrogen concentration of the effluent from the ion exchange tower in a timely manner. When the total nitrogen concentration of the effluent approaches the set value, first turn off the booster pump, then close the inlet valve and the backwash liquid valve, and open the outlet valve of the backwash desorption device. Use the backwash pump to pump 5-10% sodium chloride regeneration liquid (elution liquid) into the ion exchange tower to the liquid level, turn off the regeneration pump, aerate for 5 minutes, stop aeration and soak for 15 minutes, aerate for another 5 minutes, stop aeration and soak for 15 minutes, repeat four to six times, and backwash regeneration for a total of 60-90 minutes to elute the nitrate adsorbed in the anion exchange resin. The eluent regeneration liquid is pumped into the reverse osmosis device for total nitrogen recovery, and separated into a 10-20% concentrate (high-concentration total nitrogen water) and an 80-90% dialysate through reverse osmosis filtration. The concentrate (high-concentration total nitrogen water) is pumped into the evaporation crystallization system to crystallize and recover nitrates.

[0280] (7) Concentration of anion exchange resin regenerated solution: The total nitrogen-rich regenerated solution generated from the regeneration of anion exchange resin in step (7) is pumped into the reverse osmosis concentration system, and the regenerated solution is separated into 10-20% concentrate and 80-90% dialysate through the reverse osmosis concentration system.

[0281] (8) Evaporation and crystallization of nitrates in the concentrate: The concentrate obtained by reverse osmosis concentration in step (8) is pumped into the heat exchanger of the evaporation and crystallization system, and then into the evaporator. After evaporation and concentration, it enters the crystallization tank and crystallizes out solid nitrates.

[0282] (9) Centrifugal separation: The concentrated liquid after evaporation and crystallization in step (9) is pumped into a centrifuge and separated by centrifugation to obtain nitrate solid and mother liquor.

[0283] Example 4

[0284] A floating adsorption phosphorus removal packing material with a porous structure comprises 38% by weight of 300-mesh gypsum powder as total phosphorus adsorbent, 15% by weight of 200-mesh activated diatomaceous earth as adsorbent, 25% by weight of cement as binder, 21.5% by weight of 200-mesh stone powder as aggregate, and 0.5% by weight of foaming agent. After expansion molding, crushing, and sieving, it forms an adsorption phosphorus removal filter material with a particle size of 2-25 mm. The removal effect on total phosphorus is tested according to the following tests.

[0285] Furthermore, a method for preparing adsorption phosphorus removal packing material for a floating island-type water adsorption phosphorus removal and purification device is characterized in that the preparation method includes the following steps:

[0286] S11: Ingredients: 38% by weight of 300-mesh gypsum powder as total phosphorus adsorbent, 15% by weight of 200-mesh activated diatomaceous earth as adsorbent, 25% by weight of cement as binder, and 21.5% by weight of 200-mesh stone powder as aggregate, mixed evenly to form 600 parts of mixture (total weight is calculated as 1000 parts).

[0287] S12: Foaming: Add 0.5 parts by weight of sodium dodecylbenzenesulfonate to 399.5 parts by weight of water and stir thoroughly to produce a large amount of foam;

[0288] S13: Pulping: Add the mixture obtained in S11 to the foaming liquid in S12, stir thoroughly, and prepare a slurry;

[0289] S14: Expansion molding: The slurry prepared by S14 is fed into a molding die to be cross-linked and molded into a porous solid material;

[0290] S15: Crushing: The extruded and cross-linked solids are fed into a crusher for crushing;

[0291] S16: Sieving: The crushed material is sieved to obtain adsorption and phosphorus removal filter media with particle sizes of 2-5mm, 5-10mm, 10-20mm, and 20-40mm.

[0292] The main technical indicators of the obtained phosphorus removal filter media are as follows: the bulk density of the phosphorus removal filter media is 430-650 kg / m³. 3 Specific surface area ≥12.5m² 2 / g, compressive strength ≥2.5MPa, porosity ≥75%, dry density ≤800kg / m³ 3 Water absorption rate ≥35%, particle size range 3-40mm, total phosphorus removal rate 95% (tested on a water sample with a total concentration of 2.0mg / L).

[0293] The foregoing description has fully disclosed the specific embodiments of this application. It should be noted that any modifications made by those skilled in the art to the specific embodiments of this application do not depart from the scope of the claims. Accordingly, the scope of the claims of this application is not limited to the foregoing specific embodiments.

Claims

1. A water filtration and adsorption system for phosphorus and nitrogen removal and recovery, characterized in that... It includes a filtration device (1), an adsorption phosphorus removal device (2), a phosphorus recovery device (3), an ion exchange denitrification device (4), and a nitrogen recovery device (5), wherein the filtration device (1), the adsorption phosphorus removal device (2), the phosphorus recovery device (3), the ion exchange denitrification device (4), and the nitrogen recovery device (5) are connected in sequence; wherein: The filter device (1) is used to filter and remove solid particles and colloids in the water, and to prevent solid particles and colloids in the water from polluting and clogging the packing of the adsorption phosphorus removal device. The filter device is provided with an inlet, an outlet, a filter residue rinsing water inlet and a filter residue rinsing water outlet. The inlet of the filter device is connected to the water body. The filter device is equipped with a lift pump. The outlet of the filter device is connected to the inlet of the adsorption phosphorus removal and phosphorus recovery device. The phosphorus adsorption device (2) is used to filter and adsorb total phosphorus from water. The phosphorus adsorption device (2) includes a phosphorus adsorption bed (2-1), a phosphorus adsorption bed inlet (2-2), a phosphorus adsorption bed outlet (2-3), a support (2-4), an aeration pipe (2-5), a grid plate (2-6), a screen (2-7), and phosphorus adsorption filter media (2-8). The support (2-4) is used to support the grid plate (2-6). The grid plate (2-6) is used to support the screen (2-7), the screen (2-7) has a pore size of 2-5mm, and is used to support the adsorption phosphorus removal filter media (2-8); the inlet of the adsorption phosphorus removal bed is connected to the outlet of the booster pump, and the outlet (2-3) of the adsorption phosphorus removal bed is connected to the outlet of the clear water storage tank (319), the inlet of the eluent storage tank (322), and the inlet of the anion exchange tower (4-1) through a four-way valve; The phosphorus recovery device (3) is used to recover phosphorus eluted from the phosphorus adsorption packing. The phosphorus recovery device includes a first regeneration system, a first clean water backwashing system and a phosphorus precipitation recovery system connected in sequence. The first regeneration system is used to regenerate the adsorption and phosphorus removal filter media (2-8) in the adsorption and phosphorus removal bed. The first regeneration system includes a regeneration liquid storage tank (318), an eluent storage tank (322) and a clean water storage tank (319). The outlet of the regeneration liquid storage tank (318) is connected to the inlet (2-3) of the adsorption and phosphorus removal bed. The regeneration liquid storage tank (318) is also connected in sequence to a regeneration liquid recovery tank, a sedimentation tank and a dewatering machine. The outlet of the dewatering machine is connected to a drainage metering tank, and the solid outlet of the dewatering machine is connected to the inlet of the packaging machine. The first clean water backwashing and regeneration system is used to remove the residual regeneration solution in the adsorption and phosphorus removal packing in the adsorption and phosphorus removal bed after regeneration with regeneration solution. The first clean water backwashing and regeneration system includes a clean water storage tank (319) and a backwashing pump; the inlet of the clean water storage tank (319) is connected to the outlet (2-3) of the adsorption and phosphorus removal bed, and the outlet of the clean water storage tank (319) is connected to the phosphorus precipitation and recovery system. The ion exchange denitrification device (4) includes an anion exchange tower. The phosphorus-removed water after being adsorbed and dephosphorized by the adsorption phosphorus removal device (2) enters the ion exchange tower for removing total nitrogen from the water through ion exchange. The nitrogen recovery device (5) includes an ion exchange regeneration system, a second clean water backwashing system, and an ion exchange resin eluent system.

2. The water filtration, adsorption, phosphorus removal, and nitrogen and phosphorus recovery system as described in claim 1, characterized in that, The anion exchange tower includes anion exchange tower body (4-1), inlet (4-2), outlet (4-3), bottom column (4-10), sieve plate support (4-8), lower sieve plate (4-6), anion exchange resin (4-5), upper sieve plate (4-4), and tower cover plate (4-7). The bottom column (4-10) supports the anion exchange tower body (4-1), the sieve plate support (4-8) supports the lower sieve plate (4-6), the lower sieve plate (4-6) supports the anion exchange resin (4-5), and the upper sieve plate (4-4) encloses the anion exchange resin in the ion exchange tower. The phosphorus-removed water enters the ion exchange tower body (4-1) through the inlet (4-2) and reacts with the anion exchange resin in the tower body. Nitrate and nitrite anions in the water combine with the anion exchange resin and are adsorbed onto the anion exchange resin.

3. The water filtration, adsorption, phosphorus removal, and nitrogen and phosphorus recovery system as described in claim 1, characterized in that: The number of phosphorus adsorption beds (2-1) is 1 to N, where N is an integer from 2 to 12; the 1 to N adsorption towers are arranged in one, two or three rows in sequence.

4. The water filtration, adsorption, phosphorus removal, denitrification, and nitrogen and phosphorus recovery system as described in claim 1, characterized in that: The regenerated liquid storage tank (318) is connected in sequence to the regenerated liquid recovery tank, the sedimentation tank, and the dewatering machine. The outlet of the regenerated liquid storage tank (318) is connected to the inlet of the regenerated liquid recovery tank. The outlet of the regenerated liquid recovery tank is connected to the inlet of the sedimentation tank. The outlet of the sedimentation tank is connected to the inlet of the dewatering machine. The outlet of the dewatering machine is connected to the drainage metering tank. The solid outlet of the dewatering machine is connected to the inlet of the packaging machine.

5. The water filtration, adsorption, phosphorus removal, denitrification, and nitrogen and phosphorus recovery system as described in claim 1, characterized in that: The adsorption phosphorus removal bed uses porous calcium-based expanded adsorption phosphorus removal packing and ferric hydroxide expanded adsorption phosphorus removal packing. The porous calcium-based expanded adsorption phosphorus removal packing has a honeycomb-like porous structure and is made from 10-15% by weight of activated diatomaceous earth as the adsorbent, 25-38% by weight of gypsum powder as the total phosphorus adsorbent, 25-30% by weight of cement as the binder, 21.5-29.5% by weight of stone powder as aggregate, and 0.5% by weight of foaming agent. It is produced through expansion molding, crushing, and sieving. Its main technical indicators are: a bulk density of 430-650 kg / m³. 3 Specific surface area ≥ 11.5 m² 2 / g, compressive strength ≥2.5MPa, porosity ≥75%, dry density ≤800kg / m³ 3 The water absorption rate is ≥35%, and the particle size range is 5-40mm. The expanded hydroxyl oxide adsorption phosphorus removal filler has a honeycomb-like porous structure. Its raw materials include 25-28% gypsum and 20-25% hydroxyl oxide as phosphorus adsorbent, 20-25% cement as cement binder, 21.5-26.5% stone powder as aggregate, and 0.5% foaming agent. The filler is expanded, crushed, and sieved. Its main technical indicators are: bulk density of 430-650 kg / m³. 3 Specific surface area ≥12.5m² 2 / g, compressive strength ≥3.5MPa, porosity ≥75%, dry density ≤800kg / m³ 3 Water absorption rate ≥35%, particle size range 3~40mm.

6. The water filtration, adsorption, phosphorus removal, denitrification, and nitrogen and phosphorus recovery system as described in claim 1, characterized in that: The ion exchange resin eluent system includes a reverse osmosis total nitrogen concentration system and a nitrate nitrogen evaporation and crystallization system.

7. The water filtration, adsorption, phosphorus removal, and nitrogen and phosphorus recovery system as described in claim 6, characterized in that: The reverse osmosis total nitrogen concentration system includes a high-pressure pump, a reverse osmosis membrane module, a dialysate storage tank, and a concentrate storage tank; the inlet of the high-pressure pump is connected to the outlet of the regenerated liquid storage tank (318); the outlet of the high-pressure pump of the reverse osmosis total nitrogen concentration system is connected to the inlet of the reverse osmosis membrane module; the dialysate outlet of the reverse osmosis membrane module is connected to the inlet of the dialysate storage tank; and the concentrate outlet of the reverse osmosis membrane module is connected to the inlet of the concentrate storage tank.

8. The water filtration, adsorption, phosphorus removal, and nitrogen and phosphorus recovery system as described in claim 8, characterized in that: The nitrate nitrogen evaporation crystallization system includes valves (711), a booster pump (712), a heat exchanger (713), valves (714), an evaporator (715), valves (716), a crystallizer (717), a centrifuge (719), a condenser (720), valves (721), a cooling water storage tank (722), and a mother liquor storage tank (724). The inlet of the booster pump (712) is connected to the outlet of the mother liquor storage tank, and the outlet is connected to the inlet of the heat exchanger (713). The outlet of the heat exchanger (713) is... The outlet of the evaporator (713) is connected to the inlet of the evaporator (715), the outlet of the evaporator (713) is connected to the inlet of the crystallizer (717), and the outlet of the crystallizer (717) is connected to the inlet of the centrifuge (719). The centrifuge (719) crystallizes and separates the nitrate in the crystallizer (717) into nitrate solid and mother liquor. The nitrate solid is the recovered total nitrogen. The steam outlet of the evaporator (713) is connected to the inlet of the condenser (720), and the outlet of the condenser (720) is connected to the condensate storage tank.

9. A method for phosphorus and nitrogen removal and recovery from water by filtration and adsorption, characterized in that: The water body is treated using a filtration and adsorption phosphorus removal and nitrogen and phosphorus recovery system as described in any one of claims 1 to 8, following the steps below: (1) Filtration: Water containing 0.3-3 mg / L total phosphorus and 1-5 mg / L total nitrogen flows into the filtration device (1) to filter out small solid particles and colloids in the water, preventing small solid particles and colloids in the water from contaminating the phosphorus adsorption packing in the filtration adsorption tower. (2) Phosphorus adsorption removal: After filtration in step (1), the water enters the phosphorus adsorption bed (2-1) of the phosphorus adsorption removal device (2). At the same time, the blower is turned on for aeration. The phosphorus-containing nitrogen water flows out from top to bottom. The phosphate anions in the water are adsorbed by the phosphorus adsorption filter material in the phosphorus adsorption bed (2-1) to remove the phosphate in the water. After phosphorus removal, the water enters the phosphorus removal water pool or storage tank after being metered by the flow meter through the outlet and outlet valve of the phosphorus adsorption bed (2-1). After filtration and adsorption phosphorus removal, phosphorus-removed water is obtained. The COD in the phosphorus-removed water is ≤20mg / L and the total phosphorus is ≤0.1mg / L (for river water). The phosphorus removal rate is 90-99.5%. (3) Anion exchange denitrification: The dephosphorized water that has undergone filtration and adsorption dephosphorization in step (2) and is stored in the dephosphorized water pool or tank is pumped into the anion exchange tower. Nitrate and nitrite anions in the water are removed by anion exchange, thereby achieving total nitrogen removal from the water. The clear water after total nitrogen removal by anion exchange flows into natural water bodies through the outlet of the ion exchange tower and the four-way drainage outlet. After denitrification by anion exchange, the clear water has COD≦20mg / L, ammonia nitrogen≦0.5mg / L, total nitrogen≦1mg / L, and total phosphorus≦0.1mg / L (river) or 0.025mg / L (lake / reservoir), and the total nitrogen removal rate is 80-99.0%. (4) Regeneration of the filter adsorption phosphorus removal packing: Monitor the total phosphorus concentration of the effluent in a timely manner. When the total phosphorus concentration approaches the set value, first shut off the booster pump, then close the inlet valve and backwash liquid valve. Open the outlet valve of the backwash desorption device, and use the backwash pump to pump the alkaline washing regeneration liquid (extraction liquid) into the phosphorus adsorption bed to the liquid level. Turn off the regeneration pump, aerate for 5 minutes, stop aeration and soak for 10 minutes, then aerate for another 5 minutes, stop aeration and soak for another 10 minutes, repeating this process 4-6 times for a total backwashing cycle. After 60-90 minutes of elution, the phosphate adsorbed in the adsorption packing is eluted, and the eluent is pumped into the reaction tank of the phosphorus recovery device (3). After desorption, the phosphate is washed with water until neutral. After alkaline washing and regeneration, the acid washing and regeneration solution is pumped into the phosphorus adsorption bed to the liquid level using a backwash pump. After backwashing and regeneration for 30-60 minutes, the calcium phosphate adsorbed in the adsorption packing is eluted, and the eluent is pumped into the acid washing solution recovery tank. After acid washing and regeneration, the adsorption packing is regenerated by backwashing with water until neutral. (5) Phosphorus recovery: The backwash desorption liquid regenerated from the phosphorus adsorption packing is pumped into the reaction tank (325) of the phosphorus recovery device, a phosphorus precipitant is added, and the mixture is stirred to react the phosphate ions in the recovery liquid with calcium ions to form calcium phosphate precipitate. The backwash desorption liquid after the reaction is injected into the precipitation tank, the precipitate is separated, and the recovered calcium phosphate is obtained by drying. The phosphorus precipitant is a clear saturated calcium hydroxide solution or a 5-25% calcium chloride solution. (6) Regeneration of anion exchange resin: Monitor the total nitrogen concentration of the effluent from the ion exchange tower in a timely manner. When the total nitrogen concentration of the effluent approaches the set value, first shut off the booster pump, then shut off the inlet valve and the backwash liquid valve, and open the outlet valve of the backwash desorption device. Use the backwash pump to pump 5-10% sodium chloride regeneration solution (elution solution) into the anion exchange tower to the liquid level, shut off the regeneration pump, aerate for 5 minutes, stop aeration and soak for 15 minutes, aerate for another 5 minutes, stop aeration and soak for 15 minutes, repeat four to six times, and backwash regeneration for a total of 60-90 minutes to elute the nitrate adsorbed in the anion exchange resin. The eluent regeneration solution is pumped into the reverse osmosis device for total nitrogen recovery, and separated into a 10-20% concentrate (high-concentration total nitrogen water) and an 80-90% dialysate through reverse osmosis filtration. The concentrate (high-concentration total nitrogen water) is pumped into the evaporation crystallization system to crystallize and recover nitrates.

10. The method for filtration, adsorption, phosphorus removal, denitrification, and nitrogen and phosphorus recovery of water as described in claim 8, characterized in that: Following step (6), the following steps are also included: (7) Concentration of anion exchange resin regenerated solution: The total nitrogen-rich regenerated solution generated from the regeneration of anion exchange resin in step (7) is pumped into the reverse osmosis total nitrogen concentration system. The regenerated solution is separated into 10-20% concentrate and 80-90% dialysate through the reverse osmosis total nitrogen concentration system. (8) Evaporation and crystallization of nitrates in the concentrate: The concentrate obtained from the reverse osmosis total nitrogen concentration system in step (8) is pumped into the heat exchanger of the evaporation and crystallization system, and then into the evaporator. After evaporation and concentration, it enters the crystallization tank and crystallizes out solid nitrates. (9) Centrifugal separation: The concentrated liquid after evaporation and crystallization in step (9) is pumped into a centrifuge and separated by centrifugation to obtain nitrate solid and mother liquor.

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