Phosphorus recovery device for returned sludge

Abstract

The utility model belongs to the technical field of sewage treatment, and particularly relates to a phosphorus recovery device for returned sludge. Comprising a phosphorus removal reactor, the phosphorus removal reactor comprises a stirrer, the stirrer penetrates into the phosphorus removal reactor from the top of the phosphorus removal reactor, a filter screen is arranged below the stirrer, the phosphorus removal reactor further comprises a combined filler, the phosphorus removal reactor is connected with a solid-liquid separator, and the solid-liquid separator is connected with a conveyor; and the returned sludge enters the phosphorus removal reactor. According to the application, nitrogen and phosphorus can be removed from the returned sludge, and meanwhile, the phosphorus element is recycled and resourcefully utilized.

Description

Technical Field

[0001] The utility model belongs to the technical field of sewage treatment, and in particular relates to a phosphorus recovery device for return sludge. Background Art

[0002] Phosphorus is one of the essential nutrients for plant growth and development. Many important organic compounds in plants contain phosphorus, and phosphorus participates in various metabolic activities in plants in various forms. In order to meet the needs of plant growth, phosphorus fertilizers are applied regularly. A large amount of raw materials for the production of phosphorus fertilizers consumed each year come from phosphate rock. The proven reserves of phosphate rock in my country are 17.6 billion tons, which is converted into 10.5 billion tons of standard ore. The reserves of rich phosphate rock with a P2O5 content greater than or equal to 30% are 1.66 billion tons (1.76 billion tons of standard ore). If the current mining mode of "mining the rich and abandoning the poor" continues to decline, my country's phosphate rock will be exhausted in 20 years. Phosphorus is a non-renewable resource. The processing of medium and low-grade phosphate rock consumes more energy, which is not conducive to sustainable development.

[0003] my country treats 73 billion cubic meters of municipal sewage every year, with an average phosphorus content of 4 to 8 mg / L. The total amount of phosphorus discharged each year through the treatment of residual sludge is at least 5.84*10^5 tons, which is equivalent to 4.78 million tons based on a rich phosphate rock with a P2O5 content of 30%. The annual output of livestock and poultry manure is 3.05 billion tons, with a phosphorus content of 80 mg / L, and the annual phosphorus discharge is 244 million kilograms, which is equivalent to 1.891 million tons based on a rich phosphate rock with a P2O5 content of 30%. Sewage is rich in phosphorus and can be regarded as a renewable resource.

[0004] At present, municipal sewage and livestock and poultry manure are mainly treated by biochemical processes. In the biochemical treatment process, phosphorus is fixed in the sludge by phosphate-releasing bacteria and phosphate-accumulating bacteria, and then an appropriate amount of residual sludge is discharged to achieve the total phosphorus standard of the effluent. The discharged residual sludge is conditioned with flocculants and then separated by solid-liquid separation equipment to obtain solid sludge with a moisture content of 80%. The solid sludge is dried, co-burned and landfilled or directly sanitarily landfilled. The landfilled materials are fixed in a closed environment and cannot be normally transferred to the natural ecosystem, which leads to a large loss of phosphorus in the ecosystem and cannot be used as resources.

[0005] The residual sludge produced by sewage treatment contains a large amount of phosphorus, but the phosphorus is dispersed in the mixed liquid. It is urgent to develop a method to enrich and collect the phosphorus contained in the sludge to realize the resource utilization of sewage phosphorus and propose a new idea for my country to achieve the "dual carbon" goal. Utility Model Content

[0006] The utility model aims to provide a phosphorus recovery device for return sludge, which can remove nitrogen and phosphorus from the return sludge and simultaneously recover and utilize phosphorus element as a resource.

[0007] In order to achieve the above purpose and other related purposes, the utility model provides the following technical solutions:

[0008] A phosphorus recovery device for return sludge comprises a dephosphorization reactor, wherein the dephosphorization reactor comprises a stirrer, wherein the stirrer penetrates into the dephosphorization reactor from the top, a filter screen is arranged below the stirrer, the dephosphorization reactor further comprises a composite filler, the dephosphorization reactor is connected to a solid-liquid separator, and the solid-liquid separator is connected to a conveyor; wherein the return sludge enters the dephosphorization reactor.

[0009] Preferably, the agitator is a vertical hyperbolic mixer, which includes a power device, which is installed on the dephosphorization reactor, the power device is connected to one end of a transmission shaft, and the other end of the transmission shaft is connected to a flow guide body, and stirring blades are formed on the flow guide body; the power device drives the flow guide body to rotate through the transmission shaft.

[0010] Preferably, the upper surface of the wheel body of the flow guide body is a hyperbolic structure formed by rotating a hyperbolic generatrix around the axis of the blade body, and the stirring blades are evenly distributed on the circumference of the flow guide body.

[0011] Preferably, the dephosphorization reactor further comprises a dephosphorization reactor wall, a conical base is formed at the bottom of the dephosphorization reactor wall, the filter screen is arranged inside the conical base, and the filter screen does not contact the agitator.

[0012] Preferably, the filter screen comprises an annular filter screen support plate, a screen is arranged inside the filter screen support plate, and a plurality of liquid phase filter holes are formed on the screen.

[0013] Preferably, the composite filler is multi-layered, the outer portion of the composite filler is a spherical porous suspension filler, and the inner portion contains a phosphorus removal sponge filler and hollow suspension balls.

[0014] Preferably, the dephosphorization reactor further comprises a raw water feed pipe for raw water to enter, a dephosphorization dosing pipe for dephosphorization agent to enter, a residual sludge return pipe, and a composite filler dosing hole for the composite filler to enter;

[0015] An outlet pipe three is provided at the bottom of the conical base, a bottom discharge valve is arranged on the outlet pipe three, and the outlet pipe three is connected to a discharge pump. An outlet pipe one is provided on the side of the conical base, a solid phase discharge gate valve is arranged on the outlet pipe one, and the solid phase discharge gate valve is connected to a solid-liquid separator.

[0016] Preferably, the solid-liquid separator is conical, and a solid-liquid separator filter plate is arranged in the solid-liquid separator. A solid-liquid separator outlet valve is arranged on the outlet pipe 2 of the solid-liquid separator, and the outlet pipe 2 is connected to a discharge pump, which is also connected to a sludge discharge pipe. The conveyor is an inclined shaftless screw conveyor, and a dephosphorization filler outlet is arranged on the shaftless screw conveyor.

[0017] Preferably, the composite filler further comprises struvite crystals, and the phosphorus removal sponge filler is a square filler block with a side length of 10 to 30 mm.

[0018] Preferably, the dephosphorization agent includes a magnesium salt, and the magnesium salt includes at least one of magnesium chloride, magnesium sulfate pentahydrate, magnesium sulfate, magnesium carbonate, and magnesium bicarbonate; the dosage of the combined filler is 10% to 40% of the effective volume of the dephosphorization reactor;

[0019] Preferably, the return sludge includes at least one of the return sludge from treating municipal sewage and the return sludge from treating biogas slurry;

[0020] When the return sludge is the return sludge from treating municipal sewage, when the return sludge feed is 1m 3 , phosphorus content is 15-30 mg / L, N:P=1.1:1-1.2:1, raw water inflow is 0.33-1.1 m 3 , NH4 in raw water + -N concentration is 15-50m / L; Mg:P=1.1:1-1.5:1, 0.1-0.8L of 10%-20% concentration of phosphorus removal agent is added; the pH in the phosphorus removal reactor is maintained between 6.8 and 8.0;

[0021] When the return sludge is the return sludge for treating biogas slurry, when the return sludge feed is 1m 3 , phosphorus content is 150-250 mg / L, N:P=1.1:1-1.5:1, raw water inflow is 0.07-0.15 m 3 , NH4 in raw water + -N concentration is 2500-3000m / L; Mg:P=1.1:1-1.5:1, 1.0-8.0L of a 10%-20% concentration dephosphorization agent is added; the pH in the dephosphorization reactor is maintained between 6.8 and 8.0.

[0022] The beneficial effects of the utility model are:

[0023] This application can solve multiple technical problems, specifically:

[0024] (1) Because the residual sludge after biochemical treatment contains some calcium and magnesium ions, the sludge is digested and released into phosphate under anaerobic conditions. At the same time, under the degradation of hydrolytic acidifying bacteria, some bacterial proteins are dissolved and converted into ammonia nitrogen. Phosphate precipitates are produced from free ammonia nitrogen, phosphate, calcium and magnesium ions. The enriched phosphate precipitates are adsorbed on the contact parts, resulting in scaling of the contact surface and a reduction in the effective volume or flux.

[0025] The present application can prevent scaling of equipment and pipelines during the sludge digestion process. Specifically, the present application realizes the contact between the phosphorus removal agent and the phosphorus released by the sludge through stirring and a chemical reaction occurs to generate phosphate precipitates, in order to prevent the phosphate precipitates from accumulating at the bottom or in dead corners, resulting in the reactor structure, the effective volume of the reactor is reduced, the pipeline is scaled, and the flux is reduced. The present application uses a vertical hyperbolic mixer and utilizes a large specific surface area to obtain a large area of ​​water exchange, while directly preventing the sedimentation of suspension, greatly ensuring the contact between the phosphorus-containing precipitate and the phosphorus removal composite filler, and promoting the growth of phosphorus-containing crystals. Due to the liquid phase reflux stirring effect, the phosphorus removal composite filler frequently contacts and rubs against the reactor wall, achieving self-cleaning of the reactor wall, thereby avoiding scaling of the reactor wall, and effectively eliminating the stirring dead corner.

[0026] (2) In the prior art, in order to prevent the phosphorus in sewage from transferring to sludge, the sludge is dried and incinerated or directly landfilled. The landfilled phosphorus-containing substances are gathered in a closed space and cannot return to the ecosystem normally, resulting in irreversible damage to the phosphorus cycle in the ecological environment. The present application can recycle phosphorus and nitrogen in sewage treatment, and the recovered phosphorus-containing crystals can be dissolved, separated, and purified to obtain nitrogen fertilizer and phosphate fertilizer, and the phosphate fertilizer is returned to the ecological environment. Finally, the resource utilization of phosphorus in sewage and the sustainable development of phosphorus resources in sewage are realized.

[0027] (3) In the prior art, the biochemical phosphorus removal process of sewage usually transfers phosphorus to sludge, but the phosphorus content in the sludge is low, and it is impossible to collect phosphorus without special enrichment treatment. At present, the market generally adopts the sludge discharge method to remove phosphorus, and the phosphorus in the sludge is not collected, resulting in a huge loss of phosphorus resources. The present application transfers the biochemical sludge to the filler, and the phosphorus-containing crystals will grow on the filler to achieve the enrichment of phosphorus on the filler. The phosphorus-rich filler is separated from the sludge by solid-liquid separation equipment, and the phosphorus can be recovered by collecting and treating the phosphorus-rich filler.

[0028] (4) The present application can remove ammonia nitrogen from raw water and reduce the cost of sewage treatment. Conventional sewage treatment processes for denitrification have high investment costs, long process chains, and high operating costs. The present application utilizes free ammonia nitrogen, phosphates, and magnesium salts to form scaling crystals, which are then collected and separated into filler crystals. After separation and purification, the filler crystals are finally recycled and resourced.

[0029] (5) The present application has developed a phosphorus removal sponge filler that can remove new phosphorus and nitrogen elements, including a phosphorus removal sponge filler combined filler, which provides a skeleton for the growth of phosphorus-containing crystals and also provides feasible conditions for separating phosphorus from sludge.

[0030] In summary, the present application can remove nitrogen and phosphorus from the return sludge, and at the same time recycle and utilize phosphorus as a resource. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0032] Figure 1 It is a schematic diagram of the overall structure of the utility model;

[0033] Figure 2 This is a schematic diagram of the combined filler structure of the utility model;

[0034] Figure 3 It is a schematic diagram of the structure of the vertical hyperbolic mixer of the utility model, omitting the power device;

[0035] Figure 4 This is an effect detection diagram of the utility model;

[0036] The markings in the figure are: 1. dephosphorization reactor; 101. dephosphorization reactor wall; 102. combined filler; 103. vertical hyperboloid mixer; 104. filter screen; 105. bottom discharge valve; 106. discharge pump; 107. solid-liquid separator liquid outlet valve; 108. solid-liquid separator filter plate; 109. solid-liquid separator; 110. dephosphorization filler outlet; 111. solid phase discharge gate valve; 201. filter screen support plate; 202. liquid phase filter hole; 3 01. Spherical porous suspended filler; 302. Phosphorus removal sponge filler; 303. Hollow suspended ball; 401. Transmission shaft; 402. Diversion body; 403. Stirring blade; 501. Raw water feed pipe; 502. Phosphorus removal dosing pipe; 503. Residual sludge return pipe; 504. Composite filler injection hole; 601. Outlet pipe 1; 602. Outlet pipe 2; 603. Outlet pipe 3; 604. Sludge discharge pipe; 605. Shaftless screw conveyor. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model. Unless otherwise specified, the equipment and materials used in the embodiments can be easily obtained from commercial companies.

[0038] In the field of sewage treatment, the English abbreviations used in this application are well known.

[0039] The discharge pump 106 is a pump. The bottom discharge valve 105, the solid-liquid separator liquid discharge valve 107, and the solid phase discharge gate valve 111 are all valves.

[0040] Example 1

[0041] like Figures 1 to 3 As shown, a phosphorus recovery device for return sludge includes a phosphorus removal reactor 1.

[0042] Reference Figure 1 and Figure 3 A stirrer is provided at the center of the dephosphorization reactor 1. The stirrer penetrates into the dephosphorization reactor 1 from the top of the dephosphorization reactor 1. The stirrer is selected as a vertical hyperbolic mixer 103. The vertical hyperbolic mixer 103 includes a power device, which is installed at the top of the dephosphorization reactor 1. The power device can be a matching device of a motor and a reduction box. The power device is connected to the upper end of a transmission shaft 401, and the lower end of the transmission shaft 401 is connected to a guide body 402. A stirring blade 403 is formed on the guide body 402. The upper surface of the wheel body of the guide body 402 is a hyperbolic structure formed by the rotation of the hyperbolic generatrix around the axis of the blade body, and the stirring blades 403 are evenly distributed on the involute double arc surface (i.e., the circumference of the guide body 402). The power device drives the guide body 402 to rotate through the transmission shaft 401, thereby performing stirring work.

[0043] Reference Figure 1 The dephosphorization reactor 1 includes a dephosphorization reactor wall 101, which is rectangular. A conical base is formed at the bottom of the dephosphorization reactor wall 101. A filter screen 104 is arranged in the conical base. The filter screen 104 is located at the bottom of the flow guide 402 and does not contact the flow guide 402. The filter screen 104 includes an annular filter screen support plate 201. A circular screen is arranged in the filter screen support plate 201. A plurality of circular liquid phase filter holes 202 are formed on the screen.

[0044] The top of the dephosphorization reactor 1 also has a raw water feed pipe 501 , a dephosphorization dosing pipe 502 , a residual sludge return pipe 503 , and a composite filler dosing hole 504 .

[0045] Reference Figure 2 There is also a composite filler 102 in the dephosphorization reactor 1. The composite filler 102 is multi-layered, with at least two layers. The outside of the composite filler 102 is a spherical porous suspended filler 301, and a dephosphorization sponge filler 302 is arranged inside. It is a dephosphorization mesh sponge block, and there are hollow suspended balls 303 inside.

[0046] There is an outlet pipe 3 603 at the bottom of the conical base, there is a bottom discharge valve 105 on the outlet pipe 3 603 , and the outlet pipe 3 is connected to a discharge pump 106 .

[0047] An outlet pipe 1 601 is provided on the side of the conical base, and a solid phase discharge gate valve 111 is provided on the outlet pipe 1 601. The solid phase discharge gate valve 111 is connected to the solid-liquid separator 109 by pipeline, and the solid-liquid separator 109 can be conical. There is a solid-liquid separator filter plate 108, i.e., a filter plate, in the solid-liquid separator 109. The principle of the filter plate is well known and will not be described in detail. There is a solid-liquid separator liquid outlet valve 107 on the outlet pipe 2 602 of the solid-liquid separator 109, and the solid-liquid separator filter plate 108 is close to the side of the outlet pipe 2 602. The outlet pipe 2 602 is connected to the discharge pump 106. The discharge pump 106 is also connected to the sludge discharge pipe 604.

[0048] The solid-liquid separator 109 is also connected to an inclined shaftless screw conveyor 605 , and a dephosphorization filler outlet 110 is provided on the shaftless screw conveyor 605 .

[0049] refer to Figures 1 to 3 The operation steps of the sewage treatment device for denitrification biochemical carbon source proposed in this application are as follows:

[0050] The residual sludge from municipal sewage treatment by sewage system can be treated by the device of this application:

[0051] S1: The excess sludge of the sewage biochemical system is discharged to the phosphorus removal reactor 1 through the excess sludge return pipe 503. After the nitrogen and phosphorus-containing sewage is metabolized by microorganisms, the phosphorus element in the sewage is transferred to the excess sludge containing bacterial flocs, and the appropriate sludge concentration balance of the biochemical process is achieved by discharging the excess sludge. The excess activated sludge is composed of microbial flocs, microbial metabolic matrix and inorganic matter.

[0052] S2: Remove ammonia nitrogen and phosphorus from sewage based on the principle of struvite crystallization. The reaction formula is as follows:

[0053]

[0054] 0.5 to 2 hours after the excess sludge is discharged into the phosphorus removal reactor 1, the ORP of the mixed solution in the phosphorus removal reactor 1 drops from 100 to 200 mv to between -150 and -100 mv, and the polyphosphate bacteria in the activated sludge release phosphates under anoxic or anaerobic conditions. When the ORP value of the mixed solution drops to the turning point of -200 to -100 mv, raw water and dissolved phosphorus removal agents are pumped into the phosphorus removal reactor 1, and the raw water is transported to the phosphorus removal reactor 1 through the raw water feed pipe, and the phosphorus removal agent is transported to the phosphorus removal reactor 1 through the phosphorus removal dosing pipe 502. Under anoxic and anaerobic conditions, the phosphorus-releasing bacteria first use the residual carbon source in the excess sludge, and then use the carbon source in the raw water to release phosphate.

[0055] When the discharged residual sludge feed is 1m 3 , the phosphorus content is 15-30 mg / L. To meet the requirement of N:P=1.1:1-1.2:1, the raw water inlet volume is 0.33-1.1 m 3 , NH4 in raw water + -N concentration is 15-50m / L; to meet the requirement of Mg:P=1.1:1-1.5:1, add 0.1-0.8L of 10%-20% concentration of phosphorus removal agent.

[0056] The pH in the dephosphorization reactor 1 is maintained between 6.8 and 8.0, and the phosphate released during mixing and NH4 + Mg2 + , H2O to produce precipitates such as magnesium ammonium phosphate hexahydrate and magnesium phosphate.

[0057] The phosphorus removal agent is a magnesium salt, and the magnesium salt includes at least one of magnesium sulfate, magnesium sulfate pentahydrate, magnesium carbonate, and magnesium bicarbonate.

[0058] S3: Add the composite filler 102 into the dephosphorization reactor 1 from the composite filler adding hole 504 .

[0059] Phosphorus removal sponge filler 302:

[0060] The composite filler 102 is placed in a liquid with a pH of 2 to 3 and soaked for 2 to 6 hours to activate the initial activity of the phosphorus removal sponge filler 302. Then, after the acid solution is drained and rinsed with clean water, the composite filler 102 is placed in an activation container filled with phosphoric acid liquid, and the agitator speed of the activation container is controlled between 500 and 1000 r / min; the phosphate content in the activation container is between 100 and 500 mg / L, and magnesium salt and ammonium chloride are added according to the element content of Mg:N:P=1.0 to 1.2:1.2 to 1.5:1, and alkali solution is added to increase the pH of the mixed solution to 9 to 10.

[0061] The immersion is continued for 2 to 4 days, so that a thin layer of irregular struvite crystal nuclei is formed on the surface of the composite filler 102 .

[0062] A mixed liquid is put into the pores of the dephosphorus sponge filler 302. The mixed liquid is obtained by dissolving and mixing magnesium salt and iron salt. The free iron salt reacts with phosphate to form iron phosphate precipitate, which is suspended around the filler. At the same time, the free magnesium ions react with phosphate, ammonium ions and water to form magnesium ammonium phosphate hexahydrate. The magnesium ammonium phosphate hexahydrate uses the precipitated iron phosphate as the crystal nucleus, and the crystal nucleus collides with the skeleton of the spherical porous suspended filler 301.

[0063] The preparation method of the phosphorus removal sponge filler 302 comprises the following steps:

[0064] (1) Preparing a premixed phosphorus removal agent, the premixed phosphorus removal agent is prepared by mixing 40 to 60 parts of anhydrous magnesium sulfate (or magnesium bicarbonate, magnesium carbonate), 1 to 5 parts of activated carbon, 30 to 40 parts of pyrite (or iron sulfate, polyferric salt, polyaluminum salt), and 1 to 3 parts of talc, and stirring at 50 to 500 r / min for 1 to 2 minutes to obtain a premixed phosphorus removal agent. The particle size of each raw material is 400 to 500 mesh.

[0065] (2) A mixing barrel with a stirrer is preheated to 60-80° C. 80-90 parts of poly(ethylene glycol acetate) polyol / polyether polyol, 10-20 parts of Niax E488 modified polyether polyol, 2-6 parts of water, 1-3 parts of catalyst, 1-2 parts of surfactant, 50-60 parts of TDI, 1-2 parts of filler, and 20-40 parts of premixed phosphorus removal agent are stirred at 1000-2000 r / min for 8-15 seconds, then injected into a rectangular foaming chamber with a spray gun, and allowed to foam and dry for 2-5 minutes. The mixture is cooled to room temperature to obtain a primary phosphorus removal sponge filler, which is then transferred to the alkali solution hydrolysis and meshing process.

[0066] The catalyst adopts amine catalyst SMP such as complex amine CS90, AI, A33, etc.; the surfactant adopts a special stabilizing and pore-opening effect such as B4900, silicone oil, etc.; the filler is at least one of light magnesium carbonate, diatomaceous earth, talcum powder, bentonite, and the particle size is 300-400 mesh.

[0067] (3) Alkaline solution hydrolysis into a net method. The primary phosphorus removal sponge filler obtained in the first stage is soaked in a 10% to 20% sodium hydroxide solution at 50 to 60°C for 15 to 30 minutes, then rinsed with clean water 2 to 3 times, and then placed in a 0.5% to 5% acetic acid solution for neutralization. At the same time, magnesium and iron are used to activate the pores of the primary phosphorus removal sponge filler; then rinsed with clean water 2 to 3 times, dried, and the whole piece was cut into square filler blocks with a side length of 10 to 30 mm to obtain the phosphorus removal sponge filler 302.

[0068] S4: Under the centrifugal force of the vertical hyperbolic mixer 103, the composite filler 102 in the mixed liquid of zone I of the dephosphorization reactor 1 is parabolically moved upward from the middle to the four walls to form a circular motion, so that the phosphate precipitate and the composite filler 102 are fully stirred and mixed. The suspended magnesium ammonium phosphate hexahydrate precipitate contacts and reacts with the crystal nuclei on the surface of the composite filler 102, and the struvite crystals are grown and expanded with the block composite filler as a carrier. When the growth is large enough, a high-density composite filler crystal sphere is formed. The speed of the vertical hyperbolic mixer 103 is set at 20 to 500 r / min.

[0069] In order to cater to the flow of water, the design is to inlet water from the center of the impeller. This reduces the turbulence of the inlet water on the one hand, and ensures that the pressure of the liquid on the impeller surface is uniform on the other hand, thereby ensuring the balance of the whole machine in motion. Eight stirring blades 403 are evenly distributed on the involute double arc surface. The potential energy obtained by supplementing the inlet water with the help of the liquid's own weight pressure and the centrifugal force generated when the impeller rotates to form kinetic energy. Under the action of gravity acceleration, the liquid transitions through the hyperbolic structure and moves tangentially along the circumference of the impeller. Under the reflection of the wall of the dephosphorization reactor 1, a circulating water flow is formed from top to bottom, so a cross water flow in the axial (y) and radial (x) directions can be obtained. It is precisely because of the structural characteristics of the vertical hyperbolic mixer 103 and the characteristics of being installed close to the bottom of the pool that its working position determines that it has a direct anti-sedimentation effect on suspended matter, and an ideal stirring effect can be obtained during work, which can effectively eliminate the stirring dead corner. The large specific surface area can obtain a large area of ​​water exchange.

[0070] S5: 1 to 2 hours after adding the dephosphorization agent, open the bottom discharge valve 105, and the mixed liquid of the dephosphorization reactor 1 enters the "Zone II" through the filter screen 104. The combined filler crystal balls are retained above the filter plate. Turn on the discharge pump 106, and after the liquid phase of the dephosphorization reactor 1 is emptied to 1 / 4 to 1 / 3 of the effective height, close the discharge pump 106 and the bottom discharge valve 105, and simultaneously close the vertical hyperbolic mixer 103.

[0071] S6: Discharge the combined filler crystal balls to the solid-liquid separator 109. After opening the solid phase discharge gate valve 111 and the solid-liquid separator outlet valve 107, start the discharge pump 106 30 seconds later to achieve the liquid phase in the dephosphorization reactor 1 entering the III zone of the solid-liquid separator 109, and the liquid phase enters the discharge pump 106 through the solid-liquid separator filter plate 108, and is pumped to the next external desludging process through the discharge pump 106 and the sludge discharge pipe 604.

[0072] The composite filler crystal balls are intercepted by the solid-liquid separator filter plate 108 and gathered on the shaftless screw conveyor 605 at the bottom of the solid-liquid separator 109. The shaftless screw conveyor 605 conveys them to the external dephosphorization filler collection device through the dephosphorization filler outlet 110.

[0073] The combined filler crystal balls are discharged once a day through the solid-liquid separator 109, and the rest are discharged through the bottom discharge valve-105 to provide appropriate time for crystal growth.

[0074] S7: Collect 20% to 30% of the combined filler crystal balls in the dephosphorization reactor 1, discharge the remaining combined filler crystal balls and the combined fillers 102 accounting for 20% to 30% of the total number of combined fillers 102 in the dephosphorization reactor 1, and then pour the new combined fillers 102 into the dephosphorization reactor 1. The combined fillers 102 accounting for 20% to 30% of the total number of combined fillers 102 in the dephosphorization reactor 1 are dried at 50 to 80° C. to dehydrate the magnesium ammonium phosphate hexahydrate crystals into magnesium ammonium phosphate powder, and the magnesium ammonium phosphate is detached from the combined fillers 102 by oscillation, and the drying and oscillation are repeated multiple times to detach the crystals from the surface of the combined fillers 102. The combined fillers 102 whose surface crystals have been removed are waiting to be poured into the dephosphorization reactor 1 for use next time.

[0075] Example 2

[0076] Detection of the treatment effect of Example 1:

[0077] Total phosphorus removal effect:

[0078] By controlling the dosage of the added phosphorus removal agent, the total phosphorus removal effect of different Mg / p was tested, as shown in Table 1.

[0079] Table 1 System phosphorus removal effect data table

[0080]

[0081]

[0082] As shown in Table 2, the P content of the crystals stripped from the surface of the composite filler 102 is 13.09%, which is equal to the 13.1% P content of the 30% rich phosphate ore. However, phosphate ore needs to go through complex mining, pretreatment, acidification, leaching and extraction processes, and the operating cost is high. However, the pretreatment of the phosphorus-rich crystals separated from sewage is simple, and the crystals can be dissolved using 5% to 20% hydrochloric acid, with less strong acid usage and low operating costs.

[0083] Table 2 Table of the content of crystal elements peeled off from the surface of the phosphorus removal composite filler

[0084] Test Elements Sample element content Cx (mg / kg) Sample element content W (%) Na 2.640.23 0.26％ Mg 35.577.67 3.56％ K 1.991.83 0.20％ Ca 96.786.82 9.68％ Si 4.527.42 0.45％ S 303.22 0.03％ Al 278.48 0.03％ P 130.922.61 13.09％ Fe 411.39 0.04％ Zn 22.62 0.00％ Ba 16.64 0.00％

[0085] Example 3

[0086] Different from Example 1, reference Figure 1 and Figure 2 The phosphorus recovery device for return sludge proposed in this application operates as follows:

[0087] Reference Figures 1 to 3 The residual sludge from the sewage system used to treat biogas slurry can be treated with the device of this application:

[0088] S1: Same as implementation case 1.

[0089] S2: Remove ammonia nitrogen and phosphorus from sewage based on the principle of struvite crystallization. The reaction formula is as follows:

[0090]

[0091] 0.5 to 2 hours after the excess sludge is discharged into the phosphorus removal reactor 1, the ORP of the mixed solution in the phosphorus removal reactor 1 drops from 100 to 200 mv to between -150 and -100 mv, and the polyphosphate bacteria in the activated sludge release phosphates under anoxic or anaerobic conditions. When the ORP value of the mixed solution drops to the turning point of -200 to -100 mv, raw water and dissolved phosphorus removal agents are pumped into the phosphorus removal reactor 1, and the raw water is transported to the phosphorus removal reactor 1 through the raw water feed pipe, and the phosphorus removal agent is transported to the phosphorus removal reactor 1 through the phosphorus removal dosing pipe 502. Under anoxic and anaerobic conditions, the polyphosphate bacteria first use the residual carbon source in the excess sludge, and then use the carbon source in the raw water to release phosphate.

[0092] When the discharged residual sludge feed is 1m 3 The phosphorus content in the residual sludge discharged from sewage is 150-250 mg / L. In order to meet the requirement of N:P=1.1:1-1.5:1, the raw water inlet volume is 0.07-0.15 m 3 , NH4 in raw water + -N concentration is between 2500 and 3000 m / L; to meet the requirement of Mg:P=1.1:1 to 1.5:1, 1.0 to 8.0 L of a phosphorus removal agent with a concentration of 10% to 20% needs to be added.

[0093] The pH in the dephosphorization reactor 1 is maintained between 6.8 and 8.0, and the phosphate released during mixing and NH4 + Mg2 + , H2O to produce precipitates such as magnesium ammonium phosphate hexahydrate and magnesium phosphate.

[0094] The phosphorus removal agent is a magnesium salt, and the magnesium salt includes at least one of magnesium chloride, magnesium sulfate pentahydrate, magnesium sulfate, and magnesium carbonate.

[0095] S3: Add the composite filler 102 into the dephosphorization reactor 1. The addition amount of the composite filler 102 is 10% to 40% of the effective volume of the dephosphorization reactor 1. The dephosphorization sponge filler 302 and steps S4 to S7 are the same as those in Example 1.

[0096] Example 4

[0097] Detection of the treatment effect of Example 3:

[0098] The total phosphorus removal effect is shown in Table 3 and Figure 4 :

[0099] Table 3 Phosphorus removal data of sludge with different Mg:P

[0100]

[0101] The above description is only a preferred embodiment of the utility model and is not intended to limit the utility model. Although the utility model is described in detail with reference to the above embodiments, those skilled in the art can still modify the technical solutions recorded in the above embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model shall be included in the protection scope of the utility model.

Claims

1. A phosphorus recovery device for return sludge, characterized in that: The invention comprises a dephosphorization reactor (1), wherein the dephosphorization reactor (1) comprises a stirrer, wherein the stirrer penetrates into the dephosphorization reactor (1) from the top of the dephosphorization reactor (1), wherein a filter screen (104) is provided below the stirrer, and wherein the dephosphorization reactor (1) further comprises a composite filler (102), wherein the dephosphorization reactor (1) is connected to a solid-liquid separator (109), and wherein the solid-liquid separator (109) is connected to a conveyor; wherein the return sludge enters the dephosphorization reactor (1).

2. The phosphorus recovery device for return sludge according to claim 1, characterized in that: The stirrer is a vertical hyperbolic stirrer (103), the vertical hyperbolic stirrer (103) comprising a power device, the power device being installed on the dephosphorization reactor (1), the power device being connected to one end of a transmission shaft (401), the other end of the transmission shaft (401) being connected to a flow guide (402), and a stirring blade (403) being formed on the flow guide (402); the power device drives the flow guide (402) to rotate via the transmission shaft (401).

3. The phosphorus recovery device for return sludge according to claim 2, characterized in that: The upper surface of the wheel body of the flow guide (402) is a hyperbolic structure formed by the rotation of a hyperbolic generatrix around the axis of the blade body, and the stirring blades (403) are evenly distributed on the circumference of the flow guide (402).

4. The phosphorus recovery device for return sludge according to claim 1, characterized in that: The dephosphorization reactor (1) further comprises a dephosphorization reactor wall (101), the bottom of the dephosphorization reactor wall (101) is formed with a conical base, the filter screen (104) is arranged inside the conical base, and the filter screen (104) does not contact the agitator.

5. The phosphorus recovery device for return sludge according to claim 1, characterized in that: The filter screen (104) comprises an annular filter screen support plate (201), a screen is provided inside the filter screen support plate (201), and a plurality of liquid phase filter holes (202) are formed on the screen.

6. The phosphorus recovery device for return sludge according to claim 1, characterized in that: The combined filler (102) is multi-layered, the outside of the combined filler (102) is a spherical porous suspension filler (301), and the inside of the combined filler (102) contains a phosphorus removal sponge filler (302) and hollow suspension balls (303).

7. The phosphorus recovery device for return sludge according to claim 4, characterized in that: The dephosphorization reactor (1) further comprises a raw water feed pipe (501) for raw water to enter, a dephosphorization dosing pipe (502) for dephosphorization agent to enter, a residual sludge return pipe (503), and a composite filler dosing hole (504) for the composite filler (102) to enter; The conical base has an outlet pipe three (603) at the bottom, the outlet pipe three (603) has a bottom discharge valve (105), the outlet pipe three (603) is connected to a discharge pump (106), the conical base has an outlet pipe one (601) at the side, the outlet pipe one (601) has a solid phase discharge gate valve (111), and the solid phase discharge gate valve (111) is connected to a solid-liquid separator (109).

8. The phosphorus recovery device for return sludge according to claim 1, characterized in that: The solid-liquid separator (109) is conical, and a solid-liquid separator filter plate (108) is provided in the solid-liquid separator (109). A solid-liquid separator outlet valve (107) is provided on the outlet pipe (602) of the solid-liquid separator (109). The outlet pipe (602) is connected to a discharge pump (106), and the discharge pump (106) is also connected to a sludge discharge pipe (604). The conveyor is an inclined shaftless screw conveyor (605), and a dephosphorization filler outlet (110) is provided on the shaftless screw conveyor (605).

9. The phosphorus recovery device for return sludge according to claim 6, characterized in that: The combined filler (102) further comprises struvite crystals, and the phosphorus removal sponge filler (302) is a square filler block with a side length of 10 to 30 mm.

10. The phosphorus recovery device for return sludge according to claim 7, characterized in that: The dosage of the combined filler (102) is 10% to 40% of the effective volume of the dephosphorization reactor (1); The return sludge includes the return sludge from treating municipal sewage or the return sludge from treating biogas slurry; When the return sludge is the return sludge from treating municipal sewage, when the return sludge feed is 1m 3 , phosphorus content is 15~30mg / L, raw water inflow is 0.33~1.1m 3 , NH4 in raw water + -N concentration is 15-50m / L; 0.1-0.8L of a 10%-20% concentration phosphorus removal agent is added; the pH in the phosphorus removal reactor (1) is maintained between 6.8 and 8.0; When the return sludge is the return sludge for treating biogas slurry, when the return sludge feed is 1m 3 , phosphorus content is 150~250mg / L, raw water inflow is 0.07~0.15m 3 , NH4 in raw water + -N concentration is between 2500 and 3000 m / L; 1.0 to 8.0 L of a dephosphorization agent having a concentration of 10% to 20% is added; and the pH in the dephosphorization reactor (1) is maintained between 6.8 and 8.0.

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