CN104529027A - Device for removing phosphate from wastewater by using struvite particle crystallization method - Google Patents

Abstract

The invention relates to a device for removing phosphate in wastewater by struvite particle crystallization, which comprises an external cylinder body, a water collection and diversion cylinder, a circulation return pipe and a push flow circulation assembly. The external cylinder body is composed of an upper straight cylinder, a middle It is composed of cone cylinder and bottom head, and the upper straight cylinder is equipped with a water outlet; the water collection and diversion cylinder is located on the inner axis of the external cylinder, and is composed of the diversion cylinder and the water collection cylinder; the circulation return pipe is composed of the diversion straight pipe and the water inlet pipe , the diversion straight pipe is set vertically, its upper end extends into the diversion cylinder, the lower end is close to the bottom head, the water inlet pipe runs through the middle cone, and communicates with the diversion straight pipe; the push flow circulation component includes The stirring shaft inside the straight pipe, the push-flow impeller arranged on the stirring shaft and the frequency conversion motor driven by the stirring shaft. Compared with the prior art, the device can realize the integration of reaction, reflux, particle growth, automatic screening, struvite discharge, sedimentation and drainage, and has compact equipment, saving floor space and reducing investment.

Description

Device for removing phosphate in wastewater by crystallization of struvite particles

technical field

The invention relates to a device for removing phosphate in wastewater by struvite particle crystallization, which belongs to a device for treating phosphorus-containing waste (sewage) water and recovering phosphorus resources.

Background technique

In 2007, a blue-green algae outbreak occurred in Wuxi Taihu Lake, which caused the deterioration of surface water quality, seriously threatened the safety of local drinking water, and caused adverse social impacts. emission. In my country, a large number of various phosphorus-containing raw materials are developed and utilized in industry and agriculture. Most of the phosphorus elements enter the water environment through various channels and cause pollution. According to statistics, more than one million tons of phosphorus directly or indirectly enter the water environment every year. At the same time, phosphate rock has been listed by the Ministry of Land and Resources of my country in 2010 as one of the minerals that cannot guarantee demand, and the proven reserves of high-grade ore can only be mined for 10 to 15 years. Therefore, the problem of sustainable utilization of phosphorus has been seriously placed in front of us, and the artificial recycling of phosphorus from all aspects of production and life has become a hot issue in resource and environmental management.

The main product obtained by treating and recycling phosphate in waste (sewage) water with struvite particle crystallization technology is struvite (magnesium ammonium phosphate, MAP). MAP is a white crystalline substance with the molecular formula MgNH ₄ PO ₄ 6H ₂ O, can be formed by adding magnesium ions to waste (sewage) water containing nitrogen and phosphorus and controlling the appropriate pH value to form and obtain crystalline particles. On the one hand, nitrogen and phosphorus pollutants in waste (sewage) water can be removed, and on the other hand On the one hand, it also has the recovery value of phosphorus resources. In addition, MAP has very little reserves in nature and is a high-grade phosphate rock, which can be used as a raw material for industrial production and as an efficient agricultural slow-release fertilizer. In the waste (sewage) water treatment system, under certain water quality conditions, when the concentrations of magnesium ions (Mg ²⁺ ), ammonia ions (NH ₄ ⁺ ) and orthophosphate (PO ₄ ^3- ) reach supersaturation, natural The crystalline deposits formed can easily cause pipe blockage. Therefore, recycling can not only obtain valuable products, but also effectively reduce the nitrogen and phosphorus load in waste (sewage) water treatment facilities, avoid crystallization of equipment and pipelines during waste (sewage) water transportation, and avoid the use of The reduction of chemical sludge and the resource utilization of phosphorus can be achieved by chemical phosphorus removal. However, the traditional phosphate treatment and recovery device of granular phosphorus crystallization often has a large device height, high manufacturing cost, requires an independent external precipitation device, and needs to set up a separate external reflux system, which makes the process equipment occupy a large area. The disadvantage of large investment is not conducive to popularization and utilization.

Chinese patent CN 102690000 A discloses a method for reclaiming phosphorus in phosphorus chemical wastewater by using a struvite production process, which is carried out in the following steps: first, the phosphorus chemical wastewater is passed through a primary sedimentation tank, and the impurities in the wastewater are removed by precipitation, and the treated wastewater Collected in the first collection tank; the waste water in the first collection tank adopts the primary quicklime method to remove inorganic fluoride ions in the waste water, and the treated waste water is collected in the second collection tank; the waste water in the second collection tank is removed by cation exchange equipment Inorganic cations in wastewater, the treated ion-exchanged wastewater is collected in the third collection tank; finally, after ion-exchanged wastewater is in the struvite reactor, the pH value is adjusted between 7 and 9 with lye, and magnesium is added source and nitrogen source, and the magnesium/phosphorus molar ratio is 1.0-1.5, and the nitrogen/phosphorus molar ratio is 1.0-1.5, and the crystalline magnesium ammonium phosphate granular fertilizer is generated in the reactor. The effluent from the struvite reactor can be directly reused in the phosphorus chemical production system or discharged up to the standard according to the secondary standard of the "Integrated Wastewater Discharge Standard". The method for recovering phosphorus in the above-mentioned patents is cumbersome in process, and the required equipment occupies a large area, and the project investment is large, and the operating cost is high.

Contents of the invention

The object of the present invention is to provide a device for removing phosphate in wastewater by struvite particle crystallization with low cost, compact equipment and high efficiency in order to overcome the above-mentioned defects in the prior art.

The purpose of the present invention can be achieved through the following technical solutions:

Before designing the structural dimensions and operating technical parameters of the device, it is first necessary to grasp the water quantity and water quality indicators of the relevant phosphorus-containing waste (sewage) water. The water quality mainly includes orthophosphorus (PO ₄ ^3- -P), ammonia nitrogen (NH ₄ ⁺ -N) and magnesium ions (Mg ²⁺ ) concentrations and the pH of the raw water, economically pre-evaluate the economic value of phosphorus recovery, and technically judge the need for additional supplementary additions if the high-efficiency phosphorus recovery scheme is implemented Chemical dosage and control conditions. Generally speaking, for phosphorus-containing waste (sewage) water with good phosphorus recovery value, the orthophosphorus concentration should be greater than 40 mg/L, and with the increase of orthophosphorus concentration in waste (sewage) water and the greater the water volume, the phosphorus recovery The higher the economic and environmental benefits are, the higher the concentration of ammonia nitrogen and magnesium ions in the waste (sewage) water or the appropriate pH value (pH value should be 8.3 to 9.0) is also beneficial to reduce the cost of adding auxiliary chemicals. Economic benefits arising from improved phosphorus recovery. In addition, for waste (sewage) water containing more suspended solids, it is advisable to use a pre-sedimentation tank with a lower surface load for suspended solids precipitation pretreatment to reduce the impurity solid load of the phosphorus recovery device. Generally speaking, the surface load of the pre-settling tank It should be less than the designed surface load value of the sedimentation zone in the device.

A device for removing phosphate in waste water by struvite particle crystallization, comprising an external cylinder, a water collection and diversion cylinder, a circulation return pipe, and a push flow circulation assembly. Wherein, the outer cylinder body is composed of an upper straight cylinder, a middle cone cylinder and a bottom head connected in sequence, a discharge pipe is arranged at the lower end of the middle cone cylinder, and a discharge valve is arranged on the discharge pipe. The upper straight cylinder is provided with a water outlet; the water collection and diversion cylinder is located on the inner axis of the outer cylinder, and is composed of a diversion cylinder and a water collection cylinder connected up and down; the circulation return pipe is composed of a diversion straight pipe and a water inlet pipe Composition, the straight diversion pipe is vertically arranged on the inner axis of the outer cylinder, its upper end extends into the diversion cylinder, and its lower end is close to the bottom head. The water inlet pipe runs through the middle cone and connects with the guide The water inlet pipe is connected with a straight pipe, and an auxiliary dosing pipe is arranged on the water inlet pipe; the pushing flow circulation assembly includes a stirring shaft extending into the inside of the directing straight pipe, a pushing flow impeller arranged on the stirring shaft, and a stirring The frequency conversion motor driven by the shaft.

Further, the middle cone adopts a structure with a wide top and a narrow bottom, which is the main structural part of the formation of struvite particles, and its cone angle is between 10° and 30°.

In order to reduce the production cost, the bottom head can adopt a standardized shaped product, which can be a standard elliptical head or a dished head that can be purchased on the market.

The upper center of the bottom head is provided with a fixed diversion cone, and the top of the cone extends upward into the interior of the diversion straight pipe. The cone angle of the diversion cone is 30-60°, and the diversion cone and the The connection of the bottom head is processed into a streamline shape to ensure a good hydraulic state during the use of the device, prevent dead ends and reduce resistance loss. The height of the diversion cone is 1/3 to 2/5 of the width of the bottom head.

The top of the upper straight cylinder is provided with a water outlet weir, and the outlet weir can be selected as one of various forms such as a triangular weir, a rectangular weir or a submerged water outlet hole. The bottom of the tank has a slope of 0.01-0.1, and the lowest part of the outlet tank is provided with an outlet pipe for discharging the recycled water. The top of the outlet tank is 200mm-400mm higher than the top of the upper straight cylinder, and the outlet tank is in the shape of a square ring.

The middle part of the outer wall of the middle cone tube is provided with an observation mirror with see-through function. The material of the observation mirror should be plexiglass or PVC board, etc., and its top is flush with the lower end of the water collection tube. The height of the observation mirror is 300-600mm. The size depends on the size of the phosphorus recovery device. The larger size device should take the upper limit. The function of the observation mirror is to facilitate the observation of the formation effect of the particle bed inside the reactor and the state of the particle layer interface during the operation of the device.

Further, the diversion cylinder is cylindrical, the top of the diversion cylinder is flush with the top of the upper straight cylinder, and the inner diameter of the diversion cylinder is 2.5 to 5 times the inner diameter of the diversion straight pipe; Large and small conical cylinders, the contraction angle of the water collection cylinder is 50-65°, and there is a gap between the extension of the lower end of the water collection cylinder and the inner wall of the middle cone cylinder. s, ensure a certain distance between the diversion cylinder and the upper straight cylinder, so that the rising velocity of the outlet water is not greater than 1.0m/s, so as to ensure a better sedimentation effect and prevent the loss of fine struvite particles.

Further, the function of the diversion straight pipe is to generate downward water flow circulation under the action of the push flow circulation device, and the inner diameter of the diversion straight pipe should be such that the water flow velocity in the section is 0.5-2.0m/s. The lower end of the straight pipe is a bell mouth. The function of the bell mouth makes the circulating water flow have a good diffusion state. There is a gap between the bell mouth and the bottom head. The width of the gap should make the cross-sectional flow velocity of the gap not less than 0.2m/s. The connection between the water inlet pipe and the diversion straight pipe is roughly located in the middle of the diversion straight pipe and the lower side of the water collection cylinder. The auxiliary dosing pipe installed on the water inlet pipe can selectively add chemical agents such as ammonia nitrogen, magnesium salt and alkali agent according to needs. substances to improve phosphate removal and recovery efficiency.

Further, the frequency conversion motor is connected to the reducer, the reducer is connected to the stirring shaft through a coupling, the flow impeller is arranged on the stirring shaft, and the frequency conversion motor and the reducer are fixed on the outlet through the frame. On the water tank, the frame simultaneously connects the top of the water collecting and guiding cylinder with the water outlet tank. Among them, the frequency conversion motor and the reducer form the power mechanism of the push flow cycle, and the speed of the push flow cycle device can be controlled by frequency conversion, so that the circulation flow can be controlled in the best state according to different water quality conditions during operation; the frequency conversion motor and the speed reducer transmit the power to the impeller through the coupling and the stirring shaft, and the axial flow impeller forces the water to flow downward in the tube. The ratio of the outer diameter of the impeller to the inner diameter of the straight guide pipe is 0.98～0.90.

A diffuser is also arranged on the stirring shaft, and the diffuser is located below the push flow impeller. The diffuser adopts a streamlined structure, which can make the downward flow of water flow more smoothly and with less resistance.

When the device for removing phosphate in wastewater by struvite particle crystallization is in normal operation, the struvite particle generation zone is formed in the inner area of the outer cylinder below the lower edge of the water collection cylinder, and the return flow zone is formed inside the water collection diversion cylinder. The area above the lower edge of the water cylinder to the intersection of the outer cylinder body and the water outlet tank is the sedimentation area, and the area above the intersection of the interior of the outer cylinder body and the water outlet tank is the water outlet area.

Firstly, phosphorus-containing waste water enters from the water inlet pipe, supplemented by the auxiliary dosing pipe, and then enters the diversion straight pipe, and is fully mixed with the circulating return water. Under the action of the push flow impeller, the water flows from top to bottom in the diversion straight pipe. After flowing to the bottom head, with the help of the diversion cone, the water flows out from the bottom of the diversion straight pipe, and at the same time changes the flow direction, so that the water flow reverses from bottom to top in the struvite particle generation area, forming an internal circulation fluidized state. The water flow passes through the struvite particle generation area and then is divided into two parts into the backflow area and the sedimentation area. The sedimentation area should ensure sufficient volume and horizontal cross-sectional area, and the hydraulic retention time should not be less than 1 hour, and the surface load should not be greater than 1m ³ /m ^2.hr to ensure sufficient precipitation effect. Most of the circulating water flows back into the diversion straight pipe through the water collection cylinder and the diversion cylinder. The other small part of the water flow, whose water volume is equivalent to the wastewater inflow, enters the sedimentation area through the gap between the water collection cylinder and the middle cone cylinder, and has not yet been absorbed. The nascent struvite effectively trapped in the struvite particle generation area is separated in the sedimentation area, settles to the slope of the water collection tank and the central cone, and slides back to the struvite particle generation area, while the effluent continues to enter the effluent area. It enters the outlet tank through the outlet weir, and finally is discharged through the outlet pipe. At this time, most of the orthophosphorus in the water body forms crystal particles in the struvite formation area. The nascent struvite is in the struvite particle generation area, the crystals gradually age, grow larger and move down slowly, and finally the large particles of struvite reach the bottom of the device, and are discharged from the discharge pipe by opening the discharge valve. Obtain finished struvite with large particles.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

1. The outer cylinder of the present invention adopts the structural feature of a middle cone cylinder with a wide top and a narrow bottom, so that the rising flow rate in the struvite particle generation area can slowly and continuously change from large to small, so that struvite with different particle sizes The particles are automatically sieved to form struvite particles from small to large in size from top to bottom in the vertical direction. The discharge valve is set at the bottom to regularly discharge large struvite particles. A large number of struvite particle beds It is conducive to the crystallization transfer of the suspended magnesium ammonium phosphate precipitate to the granular bed, effectively improving the efficiency of the device and preventing the finished struvite crystal particles from being too small.

2. The present invention is an integrated structural form of struvite particle generation, precipitation, circulation reflux and water outlet, without the need for an external settling area or external reflux device, which greatly reduces the floor area, investment cost and structural complexity of the process device. It is beneficial to the widespread implementation of the struvite crystallization process.

3. The present invention adopts the form of a plug-flow circulation device. Compared with the traditional water pump return method, it has the advantages of large flow, low installed power of the motor, no need for pipelines and valves, and high efficiency. It can also adjust the speed of the motor according to the characteristics of the water quality. Therefore, the return flow can be effectively controlled, and the purpose of energy saving can be further achieved, which is conducive to reducing the power consumption in the process of removing and recovering phosphate in wastewater, and improving economic benefits.

4. The central cone structure with a large angle (10-30°) cone angle can not only effectively screen struvite particles with different particle sizes, but also make the device operate at the same effective volume or the same phosphate removal capacity. The height is greatly reduced, which reduces the processing and installation difficulty of the device, and correspondingly reduces the manufacturing cost of the device.

5. The present invention adopts a characteristic bottom head and diversion cone structure. Its flow-type structural features enable the circulating backflow water to enter the struvite particle generation area more smoothly. device efficiency.

Description of drawings

Fig. 1 is the structural representation of device of the present invention;

Fig. 2 is the flow diagram of the water flow when the device of the present invention is in operation;

Fig. 3 is a particle distribution diagram under normal operating conditions of the device of the present invention.

Labels in the figure: 1. Outer cylinder, 11. Upper straight cylinder, 12. Middle cone, 13. Bottom head, 14. Diversion cone, 15. Discharge pipe, 16. Discharge valve, 17. Discharge tank, 18. Outlet pipe, 19. Water outlet weir, 110. Observation mirror, 2. Water collection and diversion cylinder, 21. Water collection cylinder, 22. Flow diversion cylinder, 3. Push flow circulation device, 31. Frequency conversion motor, 32. Deceleration Machine, 33, shaft coupling, 34, stirring shaft, 35 push flow impeller, 36, diffuser, 37, frame, 4, circulation return pipe, 41, diversion straight pipe, 42, bell mouth, 43, water inlet pipe , 44, auxiliary dosing pipe, 5, struvite particle generation area, 6, backflow area, 7, precipitation area, 8, water outlet area.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

Example

As shown in FIG. 1 , a device for removing phosphate in wastewater by crystallization of struvite particles includes an external cylinder 1 , a water collection and diversion cylinder 2 , a circulation return pipe 4 and a push flow circulation component 3 .

Among them, the outer cylinder body 1 is composed of an upper straight cylinder 11, a middle cone cylinder 12 and a bottom head 13 connected in sequence. The middle cone cylinder 12 adopts a structure with a wide top and a narrow bottom, which is the main structural part of struvite particles. The angle is between 10° and 30°. The bottom head 13 can adopt a standardized shaped product, and can be a standard elliptical head or a dished head that can be purchased on the market.

A fixed diversion cone 14 is arranged at the upper center of the bottom head 13, and the top of the cone extends upwards into the interior of the diversion straight pipe 41. The cone angle of the diversion cone 14 is 30-60°. The connection of the head 13 is processed into a streamline shape to ensure a good hydraulic state during the use of the device, prevent dead ends and reduce resistance loss. The height of the diversion cone 14 is 1/3 to 2/5 of the width of the bottom head 13 .

The lower end of the central cone 12 is provided with a discharge pipe 15, the discharge pipe 15 is provided with a discharge valve 16, and the top straight cylinder 11 is provided with a water outlet trough 17; One of the various forms such as rectangular weir or submerged water outlet hole, etc., the outer side of the top of the upper straight cylinder 11 is connected with the water outlet tank 17, and the water outlet tank 17 surrounds the upper straight cylinder 11. The bottom of the water outlet tank 17 has a slope of 0.01 to 0.1. The lowest part of 17 is provided with outlet pipe 18 for discharging the effluent after phosphate removal and recovery. The top of effluent tank 17 is 200mm-400mm higher than the top of upper straight cylinder 11, and the effluent tank is in the shape of a square ring.

The middle part of the outer wall of the central cone 12 is provided with an observation mirror 11 with a perspective function. The material of the observation mirror 11 is preferably plexiglass or PVC board, etc., and its top is flush with the lower end of the water collection tube 21. The height of the observation mirror 11 is 300-600mm , its size depends on the size of the phosphate removal and recovery device, and the upper limit should be taken for larger-sized devices. The function of the observation mirror 11 is to facilitate the observation of the particle bed formation effect and particle size in the reactor during the operation of the device. interface conditions, etc.

The water collection and diversion cylinder 2 is located on the inner axis of the outer cylinder body 1, and is composed of a diversion cylinder 22 and a water collection cylinder 21 connected up and down; The inner diameter of the diversion tube 22 is 2.5 to 5 times of the inner diameter of the diversion straight pipe 41; There is a gap between the extension of the lower end and the inner wall of the middle cone 12. The width of the gap should be such that the rising flow rate of the water passing through the gap section is not greater than 0.1m/s, and a certain distance is ensured between the guide tube 22 and the upper straight tube 11 to make the rising flow rate of the water flow No more than 1.0m/s to ensure better sedimentation effect and prevent the loss of fine struvite particles.

The circulation and return pipe 4 is composed of a straight diversion pipe 41 and a water inlet pipe 43. The straight diversion pipe 41 is vertically arranged on the inner axis of the outer cylinder 1, and its upper end extends into the diversion tube 22, and its lower end is close to the bottom head 13. The water inlet pipe 43 runs through the middle cone tube 12 and communicates with the straight diversion pipe 41. The junction of the water inlet pipe 43 and the straight diversion pipe 41 is roughly located in the middle of the straight diversion pipe 41 and the lower side of the water receiving cylinder 21. The auxiliary dosing pipe 44 provided on the water inlet pipe 43 can selectively add chemical substances such as ammonia nitrogen, magnesium salt and alkali agent according to needs, so as to improve the removal and recovery efficiency of phosphate. The function of the diversion straight pipe 41 is to generate downward water flow circulation under the action of the push flow circulation device. It is the bell mouth 42. The function of the bell mouth 42 makes the circulating water flow have a good diffusion state. There is a gap between the bell mouth 42 and the bottom head 13. The width of the gap should make the cross-sectional flow velocity of the gap not less than 0.2m/s.

The push flow circulation assembly 3 includes a frequency conversion motor 31, a reducer 32, a coupling 33, a stirring shaft 34, a push flow impeller 35, a diffuser 36 and a frame 37, and the stirring shaft 34 extends into the inside of the guide straight pipe 41. The motor 31 is connected with the reducer 32, the reducer 32 is connected with the stirring shaft 34 through the shaft coupling 33, the frequency conversion motor 31 and the reducer 32 are fixed on the water outlet tank 17 through the frame 37, and the frame 37 guides the collected water at the same time The top of the barrel 2 is connected to the water outlet tank 17 . The push impeller 35 and the diffuser 36 are arranged on the stirring shaft 34 , and the diffuser 36 is located below the push impeller 35 . The diffuser 36 adopts a streamlined structure, which can make the water flowing downwards more smoothly and with less resistance. The frequency conversion motor 31 and the reducer 32 form the power mechanism of the push flow cycle, and the speed of the push flow cycle device can be controlled by frequency conversion, so that the circulation flow can be controlled in the best state according to different water quality conditions during operation; The flow-type push impeller 35 forces the water to flow downward in the pipe, and the ratio of the extension diameter of the push impeller 35 to the inner diameter of the guide straight pipe 41 is 0.98-0.90.

When the device for removing phosphate in waste water by struvite particle crystallization is in normal operation, the struvite particle generation area 5 is formed in the inner area of the outer cylinder 1 below the lower edge of the water collection cylinder 21, and the internal composition of the water collection and diversion cylinder 2 The recirculation zone 6, the area between the lower edge of the water receiving cylinder 21 and the intersection of the outer cylinder 1 and the water outlet tank 17 is the sedimentation zone 7, and the area above the intersection of the interior of the outer cylinder 1 and the water outlet tank 17 is the water outlet area 8.

Fig. 2 is a diagram of water flow when the device of the present invention is in operation, and Fig. 3 is a diagram of particle distribution of the device of the present invention under normal operating conditions. Phosphorus-containing wastewater enters from the water inlet pipe 43 after being pretreated by natural precipitation, and according to the background concentration and pH value of orthophosphorus, ammonia nitrogen, and magnesium ions in the treated waste (sewage) water, an appropriate amount of ammonium salt is selected and added through calculation and analysis (comprising reagents such as ammoniacal liquor, ammonium chloride or ammonium sulfate), magnesium salt (comprising reagents such as magnesium chloride or magnesium sulfate) and alkali (generally reagents such as sodium hydroxide or potassium hydroxide), the reagent solution is added from auxiliary dosing pipe 44 , after being fully mixed with the raw water in the water inlet pipe 43, they enter into the diversion straight pipe 41 together and fully mix with the circulating backflow water. Behind the bottom head 13, under the auxiliary action of the diversion cone 14, the water flows out from the bottom of the diversion straight pipe 41, and at the same time changes the flow direction, so that the water flow reverses from bottom to top in the struvite particle generation area 5, forming Fluidized state of internal circulation. The water flow passes through the struvite particle generation zone 5 and then divides into two parts of the water flow and enters the recirculation zone 6 and the sedimentation zone 7 respectively. The sedimentation zone 7 ensures sufficient volume and horizontal cross-sectional area to ensure that the hydraulic retention time HRT should not be less than 1 hour, and the surface load should not be less than 1 hour. More than 1m ³ /m ² .hr to ensure sufficient sedimentation effect. Most of the circulating water flows through the water receiving tube 21 and the diversion tube 22 and then returns to the diversion straight pipe 41, and the other small part of the water flow, whose water volume is equivalent to the wastewater inflow, passes through the gap between the water receiving tube 21 and the middle cone tube 12 Entering the sedimentation area 7, the nascent struvite that has not been effectively intercepted by the struvite particle generation area 5 is separated in the sedimentation area 7, settles on the slope of the water collection tube 21 and the middle cone tube 12, and slides back to the struvite particles generation zone 5, while the effluent continues to go up into the effluent zone 8, enters the effluent tank 17 through the effluent weir 19, and finally discharges through the effluent pipe 18 to achieve the effect of purifying waste (sewage) water. Crystalline particles are formed in the bezoar formation zone 5 . The nascent struvite is in the area where the struvite particles are produced, the crystals are gradually aging, growing larger and moving down slowly, and finally the large particles of struvite reach the bottom of the device, and are discharged from the discharge pipe 15 by opening the discharge valve 16 Discharge to obtain the finished product of struvite with large particles.

The above descriptions of the embodiments are for those of ordinary skill in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments, and apply the general principles described here to other embodiments without creative effort. Therefore, the present invention is not limited to the above-mentioned embodiments. Improvements and modifications made by those skilled in the art according to the disclosure of the present invention without departing from the scope of the present invention should fall within the protection scope of the present invention.

Claims (10)

1. A device for removing phosphate in waste water by struvite particle crystallization, characterized in that it comprises an external cylinder (1), a water collection and diversion cylinder (2), a circulation return pipe (4) and a push flow circulation assembly (3), where, The outer cylinder (1) is composed of an upper straight cylinder (11), a middle conical cylinder (12) and a bottom head (13) connected in sequence, and a water tank (17) is arranged outside the upper straight cylinder (11); The water collection and diversion cylinder (2) is located on the inner axis of the outer cylinder (1), and is composed of a diversion cylinder (22) and a water collection cylinder (21) connected up and down, and the interior of the water collection and diversion cylinder forms a return area (6), the inner area of the outer cylinder (1) located below the lower edge of the water collection cylinder (21) is the struvite particle generation area (5), and the lower edge of the water collection cylinder (21) is above the outer cylinder (1) and The area between the intersections of the water outlet grooves (17) is the sedimentation area (7), and the area above the intersection of the interior of the outer cylinder (1) and the water outlet grooves (17) is the water outlet area (8); The circulation return pipe (4) is composed of a straight diversion pipe (41) and a water inlet pipe (43), and the straight diversion pipe (41) is vertically arranged on the inner axis of the outer cylinder (1), Its upper end extends into the inside of the guide tube (22), and its lower end is close to the bottom head (13). The water inlet pipe (43) runs through the middle cone tube (12) and communicates with the guide straight tube (41); The plug flow circulation assembly (3) extends into the inside of the diversion straight pipe (41); Phosphorus-containing wastewater enters the diversion straight pipe (41) from the water inlet pipe (43), fully mixes with the circulating return water, and enters the struvite particle generation area (5) under the action of the push flow circulation component (3) to form crystal particles, Most of the water flows back into the diversion straight pipe (41) from the backflow area (6), and a small part of the water flow enters the sedimentation area (7), and the nascent struvite that has not been effectively intercepted by the struvite particle generation area (5) The sedimentation zone (7) is separated, and the sediment slides back to the struvite particle generation zone (5), while the effluent continues to go up into the effluent zone (8) for discharge. 2. the device for removing phosphate in a kind of struvite particle crystallization method according to claim 1, is characterized in that, the top center position of described bottom head (13) is provided with fixed diversion cone (14), the top of the cone extends upwards into the inside of the diversion straight pipe (41), the cone angle of the diversion cone (14) is 30-60°, the diversion cone (14) and the bottom head (13) The joints are processed into a streamline shape, and the height of the diversion cone (14) is 1/3～2/5 of the width of the bottom head (13). 3. a kind of struvite particle crystallization method according to claim 1 removes the device of phosphate in waste water, it is characterized in that, described middle part cone (12) adopts wide upper narrow structure, and its cone angle is in Between 10° and 30°, the lower end of the middle cone (12) is provided with a discharge pipe (15). 4. the device for removing phosphate in a kind of struvite particle crystallization method according to claim 1, is characterized in that, described top straight cylinder (11) top is provided with outlet weir (19), top straight cylinder (11) ) top outside is connected with the outlet tank (17), the outlet tank (17) surrounds the upper straight cylinder (11), the bottom of the outlet tank (17) has a slope of 0.01～0.1, and the lowest part of the outlet tank (17) is set Outlet pipe (18). 5. The device for removing phosphate in waste water by struvite particle crystallization according to claim 1, characterized in that an observation mirror (11) is arranged in the middle of the outer wall of the middle cone (12). 6. the device for removing phosphate in a kind of struvite particle crystallization method according to claim 1, is characterized in that, described guide tube (22) is cylindrical, and the guide tube (22) The top is flush with the top of the upper straight tube (11), and the inner diameter of the diversion tube (22) is 2.5 to 5 times the inner diameter of the diversion straight tube (41); , the contraction angle of water receiving tube (21) is 50～65 °, leaves a slit between the lower end extension of water receiving tube (21) and the middle cone tube (12) inwall. 7. a kind of struvite particle crystallization method according to claim 1 removes the device of phosphate in waste water, it is characterized in that, described diversion straight pipe (41) lower end is bell mouth (42), and bell mouth ( 42) There is a gap between the bottom head (13). 8. a kind of struvite particle crystallization method according to claim 1 removes the device of phosphate in waste water, it is characterized in that, described push-flow circulation assembly (3) comprises stretching into diversion straight pipe (41) Internal stirring shaft (34), the push-flow impeller (35) that is arranged on the stirring shaft (34) and the frequency conversion motor (31) driven by the stirring shaft (34); the frequency conversion motor (31) and the speed reducer ( 32) is connected, the speed reducer (32) is connected with the stirring shaft (34) through a shaft coupling (33), and the described plug flow impeller (35) is arranged on the stirring shaft (34), and the described variable frequency motor (31) and speed reducer (32) are fixed on the water outlet tank (17) by frame (37), and this frame (37) links to each other with the water outlet tank (17) at the same time with the top of the water receiving diversion tube (2). 9. the device for removing phosphate in a kind of struvite particle crystallization method according to claim 1, is characterized in that, the extension diameter of described plug flow impeller (35) and diversion straight pipe (41) internal diameter The ratio is 0.98 to 0.90. 10. the device for removing phosphate in a kind of struvite particle crystallization method according to claim 1, is characterized in that, described stirring shaft (34) is provided with diffuser (36), and this diffuser ( 36) be positioned at the below of plug flow impeller (35).