PAC dosing system device with accurate metering function

Abstract

The invention belongs to the technical field of sewage dosing treatment, and particularly relates to a PAC dosing system device with accurate metering, the PAC dosing system device comprises a mixing tank and a containing tank, the outer wall of the mixing tank is fixedly connected with a first bent rod and a second bent rod, the containing tank is located on the upper side of the mixing tank and fixed at the end part of the first bent rod, and the second bent rod is fixed at the end part of the second bent rod; a connecting plate is fixed to the end of the second bent rod. PAC is pumped into the containing tank through the metering pump, preliminary accurate metering of the PAC is achieved, in the PAC feeding process, quantitative subpackaging of the PAC is achieved through rotation of the discharging disc, accurate metering of the PAC is achieved again, and then quantitative feeding of the PAC into the dispersing groove in batches is achieved through rotation of the discharging disc; the PAC is sprayed into the mixing tank through the rotation of the dispersion tank to be in contact with the sewage, so that the PAC is in full contact with the sewage before stirring, the fusion is more sufficient during stirring, and the problem that stirring and mixing are not thorough after one-time feeding is adopted traditionally is avoided.

Description

Technical Field

[0001] This invention relates to the field of wastewater dosing technology, and more particularly to a PAC dosing system device with precise metering. Background Technology

[0002] Polyaluminum chloride (PAC), as a highly efficient inorganic polymeric coagulant, is widely used in water treatment, papermaking, printing and dyeing, and other industries. The accuracy of its dosage and the rapid and uniform mixing effect with the treatment medium directly affect the treatment effect (such as flocculation and sedimentation rate, effluent turbidity, decolorization rate, and reagent consumption) and operating costs.

[0003] Currently, common PAC (Pharmacy Alternate Charge) dosing systems mainly include: Metering pump dosing: It can achieve high-precision quantitative delivery and is the mainstream method, but it usually needs to be used in conjunction with a separate dissolving / cooking device, such as a dissolving tank, and a subsequent mixing device, such as a mixer.

[0004] The above methods have shortcomings: PAC solutions are usually injected into the water flow or treatment tank through metering pumps. The thorough mixing of PAC with the large volume of sewage depends entirely on subsequent, independent mixing units or naturally formed turbulence. This separation of addition and efficient mixing in time and space leads to instantaneously high PAC concentrations and local oversaturation in the vicinity of the injection point, which may trigger unnecessary side reactions (such as excessive hydrolysis leading to the deactivation of active ingredients), generate fine flocs that are difficult to settle, or cause waste of the reagent. In areas far from the addition point, the PAC concentration is significantly insufficient and cannot effectively play a coagulation role. Uneven initial mixing severely weakens the rapid diffusion and initial reaction efficiency of PAC in wastewater. The efficiency of key steps such as PAC hydrolysis, charge neutralization of colloidal particles, and formation of floc nuclei is reduced in the initial contact stage, directly causing the subsequent bridging and floc growth processes to become slow and insufficient. As a result, the formed flocs are often small, loose, poorly dense, and have poor settling (or floating) performance. In order to achieve the expected treatment effect, it is often necessary to significantly increase the PAC dosage or extend the reaction time.

[0005] To address the aforementioned issues, we propose a PAC dosing system with precise metering capabilities. Summary of the Invention

[0006] The purpose of this invention is to solve the problems in the background art by proposing a PAC dosing system device with precise metering.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: a PAC dosing system device with precise metering, comprising a mixing tank and a holding tank. A first bent rod and a second bent rod are fixedly connected to the outer wall of the mixing tank. The holding tank is located above the mixing tank and fixed to the end of the first bent rod. A connecting plate is fixed to the end of the second bent rod, and an arc frame is fixed to the end of the connecting plate. A motor is fixedly embedded in the connecting plate. A feeding disc located within the arc frame is fixed to the driving end of the motor. A discharge port located directly below the holding tank is opened on the arc frame. Multiple holding ports are evenly opened on the outer wall of the feeding disc. The holding tank is connected to a metering pump, which introduces PAC into the holding tank. The motor drives the feeding disc to rotate, dispensing the PAC into the holding ports and allowing it to fall out through the discharge port. A rotatable dispersion trough is provided inside the mixing tank below the discharge port, and multiple dispersion ports are opened on the edge of the dispersion trough.

[0008] In the aforementioned PAC dosing system device with precise metering, a cavity is provided at the bottom of the mixing tank, a motor is fixed inside the cavity, the drive end of the motor extends through into the mixing tank and is fixed with a rotating rod, mixing blades are evenly distributed on the outer wall of the rotating rod, and the dispersion groove is fixed at the top of the rotating rod.

[0009] In the aforementioned PAC dosing system device with precise metering, the mixing tank has an installation port, a filter groove is fixed inside the installation port, a discharge port is provided on the side of the filter groove near the mixing tank, a filter screen is fixed inside the filter groove, and a movable scraper that contacts the upper side wall of the filter screen is provided inside the filter groove.

[0010] In the aforementioned PAC dosing system device with precise metering, the bottom of the filter tank is provided with an inclined guide surface, the lowest point of which is flush with the discharge port.

[0011] In the aforementioned PAC dosing system device with precise metering, an annular tube is fixed to the outer wall of the mixing tank. A vertically arranged piston tube is fixed to the outer wall of the annular tube. A piston plate is slidably arranged inside the piston tube. A connecting rod is fixed to the outer wall of the piston plate. A connecting spring is fixed between the outer wall of the connecting rod and the end of the piston tube. A trapezoidal block is fixed to the lower end of the connecting rod. An opening is provided on the lower outer wall of the mixing tank, located below each trapezoidal block and communicating with the cavity. A trapezoidal plate is slidably arranged inside the opening, contacting the trapezoidal block. An extension block is integrally formed at the end of the trapezoidal plate. The extension block is connected to the mixing tank. A return spring is fixedly connected between the outer walls of the tube. A magnet is fixedly embedded at one end of the trapezoidal plate located in the cavity. A rotating disk is fixedly sleeved on the outer wall of the drive end of the motor. Multiple magnet plates are evenly embedded on the outer wall of the rotating disk. The magnets on the opposite side of the magnet block and the magnet plates have the same magnetism. A piston tube II located below each filter tank is also fixed on the outer wall of the annular tube. A piston plate II is slidably arranged inside the piston tube II. A telescopic spring is fixedly connected between the piston plate II and the inner wall of the piston tube II. A crossbar is fixedly fixed on the outer wall of the piston plate II. A sliding rod slides through the filter tank. A vertical plate is fixedly connected between the crossbar and the sliding rod.

[0012] In the aforementioned PAC dosing system device with precise metering, the container is provided with a conical flow channel inside.

[0013] In the aforementioned PAC dosing system device with precise metering, the feeding disc is in contact with the inner wall of the arc frame, the lower end of the holding tank is in contact with the feeding disc, and the contact point is provided with an arc-shaped opening that is in contact with the outer wall of the feeding disc.

[0014] Compared with existing technologies, the advantages of this PAC dosing system with precise metering are: 1. A feeding disc and a dispersion trough are set up. The motor drives the feeding disc to rotate. When the medicine holding port is aligned with the flow channel, PAC flows out from the end of the flow channel into the medicine holding port. When the medicine holding port is full, it can achieve the effect of quantitative metering of PAC and the effect of dispensing PAC. When the medicine holding port containing PAC rotates to be opposite to the discharge port, the PAC in the medicine holding port can fall into the dispersion trough. Through continuous feeding and dispensing of medicine through multiple medicine holding ports, the effect of quantitative dispensing and intermittent dispensing of PAC is achieved. When the motor drives the dispersion trough to rotate, PAC can be sprinkled into the mixing tank through the dispersion port on the edge. On the one hand, the PAC that needs to be added is dispensed in multiple batches to avoid the low mixing efficiency caused by adding PAC all at once. On the other hand, the dispersed addition solves the problem that the metering pump itself does not have a dispersion function. After the PAC is dispersed, the contact area with the sewage is increased, avoiding the problem of low mixing efficiency with sewage caused by concentrated addition. 2. The dispersion tank is connected to the rotating rod. The motor drives the rotating rod and the mixing blades to rotate, and at the same time, it drives the dispersion tank to rotate. PAC is sprayed out from the dispersion port and comes into contact with the sewage. The mixing blades stir and mix the sewage and PAC, and PAC is slowly added to the sewage in a throwing manner. This achieves the step-by-step and throwing method of PAC to increase the contact area with the sewage, ensuring that the sewage and PAC are fully mixed. 3. A rotating disk is set up. During the rotation of the rotating disk, the magnetic plate rotates intermittently and is opposite to the magnetic block. The magnetic repulsion between the magnetic plate and the magnetic block pushes the magnetic block and the trapezoidal plate to move outward. Since the inclined surfaces of the trapezoidal block and the trapezoidal plate are in contact, as the trapezoidal plate moves outward, it gradually pushes the trapezoidal block, the connecting rod and the piston plate upward, so that the airflow in the annular tube and the piston tube 1 flows into the piston tube 2, pushing the vertical plate, the sliding rod and the scraper to move outward, so as to achieve the cleaning of the filter screen surface by the scraper. In summary, this invention uses a metering pump to pump PAC into a holding tank, achieving initial accurate metering of PAC. During the PAC addition process, the rotation of the feeding disc enables quantitative dispensing of PAC, again achieving accurate metering. Subsequently, the rotation of the feeding disc enables quantitative batches of PAC to be added into a dispersion tank. The rotation of the dispersion tank then causes the PAC to be sprayed into a mixing tank to come into contact with the wastewater. This ensures that the PAC and wastewater have fully contacted before agitation, resulting in more thorough mixing during agitation and avoiding the problem of incomplete mixing after a single addition, as is common in traditional methods. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the external structure of a PAC dosing system device with precise metering proposed in this invention; Figure 2 This is a partial structural schematic diagram of a PAC dosing system device with precise metering proposed in this invention; Figure 3 This is a schematic diagram of the arc frame structure in a PAC dosing system device with precise metering proposed in this invention; Figure 4 This is a schematic diagram of the feeding disc in a PAC dosing system device with precise metering proposed in this invention; Figure 5 This is a partial bottom structure schematic diagram of a PAC dosing system device with precise metering proposed in this invention; Figure 6 This is a schematic diagram of the mixing tank in a PAC dosing system device with precise metering proposed in this invention; Figure 7This is a schematic diagram of the connection between the annular pipe, the filter tank, and the trapezoidal plate in a PAC dosing system device with precise metering proposed in this invention. Figure 8 This is a schematic diagram of the filter tank in a PAC dosing system device with precise metering proposed in this invention; Figure 9 This is a cross-sectional schematic diagram of the holding tank in a PAC dosing system device with precise metering proposed in this invention.

[0016] In the diagram: 1 Mixing tank, 2 Bend rod one, 3 Bend rod two, 4 Container tank, 5 Connecting plate, 6 Motor, 7 Arc frame, 8 Discharge disc, 9 Discharge port, 10 Medicine container, 11 Motor, 12 Rotating rod, 13 Mixing blade, 14 Dispersion tank, 15 Dispersion port, 16 Filter tank, 17 Filter screen, 18 Sliding rod, 19 Annular tube, 20 Piston tube one, 21 Connecting spring, 22 Trapezoidal block, 23 Extension block, 24 Return spring, 25 Trapezoidal plate, 26 Rotating disc, 27 Opening, 28 Mounting port, 29 Guide surface, 30 Scraper, 31 Piston tube two, 32 Vertical plate, 33 Flow channel, 34 Discharge port. Detailed Implementation

[0017] The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0018] Reference Figures 1-9 A PAC dosing system with precise metering includes a mixing tank 1 and a holding tank 4. The holding tank 4 has a conical flow channel 33 inside, which gathers PAC inwards, allowing it to flow out quickly and smoothly, avoiding accumulation at the edges. A first bent rod 2 and a second bent rod 3 are fixedly connected to the outer wall of the mixing tank 1. The holding tank 4 is located above the mixing tank 1 and fixed to the end of the first bent rod 2. A connecting plate 5 is fixed to the end of the second bent rod 3, and an arc frame 7 is fixed to the end of the connecting plate 5. A motor is fixedly embedded in the connecting plate 5. 6. The drive end of the motor 6 is fixed with a feeding disc 8 located inside the arc frame 7. The arc frame 7 has a discharge port 9 located directly below the holding tank 4. Multiple medicine holding ports 10 are evenly distributed on the outer wall of the feeding disc 8. The feeding disc 8 is in contact with the inner wall of the arc frame 7. The lower end of the holding tank 4 is in contact with the feeding disc 8, and the contact point has an arc-shaped opening that fits with the outer wall of the feeding disc 8. The holding tank 4 is connected to a metering pump. The metering pump introduces PAC into the holding tank 4. The external metering pump pumps a fixed amount of PAC into the holding tank 4 for placement.

[0019] Motor 6 drives the feeding disc 8 to rotate. When the medicine holding port 10 is aligned with the flow channel 33, PAC flows out from the end of the flow channel 33 into the medicine holding port 10. When the medicine holding port 10 is full, it can also achieve the effect of quantitative metering of PAC and the effect of dispensing PAC. Motor 6 then drives the feeding disc 8 to rotate. When the medicine holding port 10 containing PAC rotates to be opposite to the discharge port 9, the PAC in the medicine holding port 10 can fall into the dispersion tank 14. Through the continuous loading and dispensing of medicine through multiple medicine holding ports 10, the effect of quantitative dispensing and intermittent dispensing of PAC is achieved. When the subsequent motor 11 drives the dispersion tank 14 to rotate, PAC can be sprinkled into the mixing tank 1 through the dispersion port 15 on the edge. On the one hand, the PAC that needs to be added is dispensed into the mixing tank, avoiding the low mixing efficiency caused by adding PAC all at once. On the other hand, the problem of the metering pump itself not having a dispersion function is solved by using the dispersed input method.

[0020] To further explain, the size of the medicine-holding opening 10 is uniform, so the amount of PAC installed in a single medicine-holding opening 10 is fixed. By adding PAC into a single medicine-holding opening 10, a quantitative PAC delivery is completed in one delivery process. As the feeding disc 8 continues to rotate, two or three delivery processes can be completed, achieving multiple delivery and also having the effect of quantitative delivery.

[0021] The motor 6 drives the feeding disc 8 to rotate, causing PAC to be dispensed into the container 10 and discharged through the outlet 9. The mixing tank 1 is equipped with a rotatable dispersion trough 14 located below the outlet 9. The dispersion trough 14 has multiple dispersion ports 15 located at its edges. The bottom of the mixing tank 1 has a cavity, in which a motor 11 is fixed. The drive end of the motor 11 extends through into the mixing tank 1 and is fixed with a rotating rod 12. Mixing blades 13 are evenly distributed on the outer wall of the rotating rod 12. The dispersion trough 14 is fixed to the top of the rotating rod 12. The motor 11 drives the rotating rod 12, the mixing blades 13, and the dispersion trough 14 to rotate, so that the mixing blades 13 agitate the sewage and PAC, while the PAC is simultaneously dispersed into the mixing tank 1 through the dispersion trough 14, achieving the effect of adding while agitating.

[0022] The mixing tank 1 has an installation port 28, and a filter tank 16 is fixed inside the installation port 28. A discharge port 34 is provided on the side of the filter tank 16 near the mixing tank 1. A filter screen 17 is fixed inside the filter tank 16. A movable scraper 30 is provided inside the filter tank 16 and contacts the upper side wall of the filter screen 17. An inclined guide surface 29 is provided at the bottom of the filter tank 16. The lowest point of the guide surface 29 is flush with the discharge port 34. The sewage to be treated on the outside is pumped into the filter tank 16 and undergoes preliminary filtration through the filter screen 17. The guide surface 29 can guide the filtered sewage to the discharge port 34, so that the sewage can flow out from the discharge port 34 into the mixing tank 1. The movable scraper 30 can scrape and clean the surface of the filter screen 17, pushing the impurities on the filter screen 17 to both sides and accumulating, avoiding the impurities from clogging the filter screen 17 and affecting the filtration of the water, and ensuring the normal filtration of sewage.

[0023] An annular tube 19 is fixed to the outer wall of the mixing tank 1. A vertically arranged piston tube 20 is fixed to the outer wall of the annular tube 19. A piston plate 1 is slidably arranged inside the piston tube 20. A connecting rod is fixed to the outer wall of the piston plate 1. A connecting spring 21 is fixed between the outer wall of the connecting rod and the end of the piston tube 20. A trapezoidal block 22 is fixed to the lower end of the connecting rod. An opening 27 is opened on the lower outer wall of the mixing tank 1, located below each trapezoidal block 22 and communicating with the cavity. A trapezoidal plate 25 is slidably arranged inside the opening 27, contacting the trapezoidal block 22. An extension block 23 is integrally formed at the end of the trapezoidal plate 25. A return spring 24 is fixedly connected between the extension block 23 and the outer wall of the mixing tank 1. A magnet block is fixedly embedded at one end of the trapezoidal plate 25 located in the cavity. A rotating disk 26 is fixedly sleeved on the outer wall of the drive end of the motor 11. Multiple magnet plates are evenly embedded on the outer wall of the rotating disk 26. The magnet blocks and magnet plates have the same magnetism on opposite sides. A piston tube 2 31 located below each filter tank 16 is also fixed on the outer wall of the annular tube 19. A piston plate 2 is slidably arranged inside the piston tube 2 31. A telescopic spring is fixedly connected between the piston plate 2 and the inner wall of the piston tube 2 31. A spring is fixedly fixed on the outer wall of the piston plate 2. A horizontal bar and a sliding rod 18 slide through the filter tank 16. A vertical plate 32 is fixedly connected between the horizontal bar and the sliding rod 18. The motor 11 drives the mixing blades 13 to rotate while simultaneously driving the rotating disk 26 to rotate. During the rotation of the rotating disk 26, the magnet plate rotates intermittently and faces the magnet block. The magnetic repulsion between the magnet plate and the magnet block pushes the magnet block and the trapezoidal plate 25 to move outward. Since the inclined surfaces of the trapezoidal block 22 and the trapezoidal plate 25 are in contact, as the trapezoidal plate 25 moves outward, it gradually pushes the trapezoidal block 22, the connecting rod, and the piston plate upward, causing the annular tube 19 to move upward. The airflow in piston tube 20 flows into piston tube 31, pushing the vertical plate 32, sliding rod 18 and scraper 30 to move outward, thus cleaning the surface of filter screen 17 with scraper 30. When the magnet plate rotates away from the magnet block, trapezoidal plate 25 is reset under the elastic force of reset spring 24, and connecting rod and trapezoidal block 22 are reset under the elastic force of connecting spring 21. Under the reverse elastic force of extension spring, vertical plate 32, sliding rod 18 and scraper 30 move inward. Through the reciprocating action of the above actions, the scraper 30 moves back and forth, completing the continuous cleaning of filter screen 17.

[0024] In summary, this design achieves both precise metering and quantitative dispensing: 1. A fixed amount of PAC solution is pumped into the holding tank 4 using an external standard metering pump to complete the first accurate measurement; 2. During the PAC dispensing process, motor 6 drives the feeding disc 8 to rotate intermittently. When a certain dispensing port 10 rotates to directly below the outlet of the conical flow channel 33 at the bottom of the holding tank 4, a fixed amount of PAC solution (its volume is equal to the fixed volume of the dispensing port 10) flows in and fills the dispensing port 10, realizing a second precise metering control and quantitative dispensing. Each dispensing port 10 serves as a standard metering unit, ensuring that the amount of PAC dispensed each time is highly consistent. This improved the overall accuracy and controllability of PAC dosing.

[0025] This design achieves batch-based, decentralized addition and optimized initial mixing: 1. When the PAC-filled container 10 rotates with the feeding disc 8 to the discharge port 9, the PAC falls into the dispersion tank 14 below it. 2. The dispersion tank 14 is driven to rotate at high speed by the motor 11 through the rotating rod 12. The PAC solution falling into the dispersion tank 14 is evenly and finely sprayed into the sewage being stirred in the mixing tank 1 through multiple dispersion ports 15 on its edge under the action of centrifugal force.

[0026] This batch-based, low-volume, and highly dispersed application method contrasts sharply with the traditional single-point centralized application: It avoids instantaneous local oversaturation: each dosage is small and quickly dispersed, greatly reducing the risk of forming an area with excessively high PAC concentration near the dosage point.

[0027] Increased initial contact area: The scattering method allows the PAC solution to come into contact with the sewage over a large area in the form of numerous small droplets, which significantly improves the efficiency of the initial collision and reaction between PAC and colloidal particles in the sewage.

[0028] Promotes uniform mixing: The dispersed PAC droplets naturally diffuse with the wastewater flow, making them easier to be captured by the rotating mixing blades 13 and incorporated into the overall mixed flow, laying a good foundation for subsequent efficient mixing.

[0029] Synergistic effect of simultaneous mixing and dynamic dosing: 1. The motor 11 drives the rotating rod 12 and the mixing blade 13 to rotate, which strongly stirs the sewage in the mixing tank 1, forming turbulence and promoting the mixing, reaction and floc growth of PAC and sewage.

[0030] 2. At the same time, the dispersion tank 14 is fixed coaxially with the rotating rod 12 and rotates synchronously with the stirring mechanism. This means that the dispersion and addition of PAC and the mechanical stirring of sewage are carried out synchronously and spatially coupled. The newly added PAC directly enters a strong mixing environment and can be quickly dispersed and mixed.

[0031] This collaborative mechanism of "dispersed addition and vigorous stirring" completely solves the problem of asynchronous addition and mixing in traditional systems, enabling PAC to be in a highly efficient mixing state from the moment it enters the system, significantly shortening the mixing time and improving the mixing uniformity and flocculation efficiency.

[0032] Integrated filtration and self-cleaning functions: 1. Wastewater undergoes preliminary filtration through filter screen 17 in filter tank 16 to remove large particulate impurities and protect subsequent dosing and stirring components; 2. The power generated by the rotation of motor 11 causes the magnetic plate on the rotating disk 26 to periodically repel the magnetic block on the trapezoidal plate 25. The linear reciprocating motion is converted into air pressure changes in piston tube 20 through the trapezoidal inclined plane mechanism, which in turn drives the piston in piston tube 31 to move, and finally drives scraper 30 to perform reciprocating scraping motion on the surface of filter screen 17. This device requires no additional power source and automatically and continuously cleans the filter screen 17 while mixing and stirring, effectively preventing the filter screen 17 from clogging and ensuring the stability of the sewage filtration flow and the continuous operation of the system.

[0033] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A PAC dosing system device with precise metering, comprising a mixing tank (1) and a holding tank (4), characterized in that, The outer wall of the mixing tank (1) is fixedly connected with a bent rod one (2) and a bent rod two (3), the containing tank (4) is located on the upper side of the mixing tank (1) and is fixed at the end of the bent rod one (2), the end of the bent rod two (3) is fixedly connected with a connecting plate (5), the end of the connecting plate (5) is fixedly connected with a circular arc frame (7), the motor (6) is fixedly embedded on the connecting plate (5), the driving end of the motor (6) is fixedly connected with a discharging disc (8) located in the circular arc frame (7), a discharging port (9) located directly below the containing tank (4) is formed in the circular arc frame (7), a plurality of medicine containing openings (10) are uniformly formed in the outer wall of the discharging disc (8), the containing tank (4) is connected with a metering pump, PAC is introduced into the containing tank (4) through the metering pump, the discharging disc (8) is driven to rotate by the motor (6) so that the PAC is divided into the medicine containing openings (10) and falls out through the discharging port (9), the mixing tank (1) is provided with a rotatable dispersion tank (14) located below the discharging port (9), a plurality of dispersion ports (15) located at the edge of the dispersion tank (14) are formed in the dispersion tank (14).

2. A PAC dosing system apparatus with precise metering as claimed in claim 1, wherein, A cavity is formed in the bottom of the mixing tank (1), a motor (11) is fixedly arranged in the cavity, the driving end of the motor (11) extends into the mixing tank (1) and is fixedly connected with a rotating rod (12), a plurality of mixing blades (13) are uniformly distributed on the outer wall of the rotating rod (12), and the dispersion tank (14) is fixedly arranged at the top end of the rotating rod (12).

3. A PAC dosing system apparatus with precise metering as claimed in claim 1, wherein, An installation port (28) is formed in the side wall of the mixing tank (1), a filter tank (16) is fixedly embedded and installed in the installation port (28), a discharge port (34) is formed in the side wall bottom of the filter tank (16) close to the mixing tank (1), a filter screen (17) for preliminarily filtering larger suspended matters in sewage is fixedly installed in the filter tank (16), and a scraper (30) horizontally movable along the length direction of the filter tank (16) is further arranged in the filter tank (16), and the bottom edge of the scraper (30) is in close contact with the upper surface of the filter screen (17).

4. A PAC dosing system apparatus with precise metering as claimed in claim 3, wherein, The bottom inner surface of the filter tank (16) is designed as an inclined flow guide surface (29), the lowest point of the flow guide surface (29) is flush with the bottom edge of the discharge port (34), so that the filtered sewage can be smoothly collected and completely flow into the mixing tank (1) through the discharge port (34), and accumulation at the bottom of the filter tank (16) is avoided.

5. A PAC dosing system apparatus with precise metering as claimed in claim 3, wherein, The outer wall of the mixing tank (1) is fixed with an annular pipe (19), the outer wall of the annular pipe (19) is fixed with a vertically arranged piston pipe one (20), the piston pipe one (20) is slidably provided with a piston plate one, the outer wall of the piston plate one is fixed with a connecting rod, the outer wall of the connecting rod and the end of the piston pipe one (20) are fixed with a connecting spring (21), the lower end of the connecting rod is fixed with a trapezoidal block (22), the lower end of the mixing tank (1) is provided with an opening (27) which is located below each trapezoidal block (22) and is communicated with the cavity, the opening (27) is slidably provided with a trapezoidal plate (25) which is in contact with the trapezoidal block (22), the end of the trapezoidal plate (25) is integrally formed with an extension block (23), the extension block (23) and the outer wall of the mixing tank (1) are fixedly connected with a return spring (24), one end of the trapezoidal plate (25) in the cavity is fixedly embedded with a magnet block, the outer wall of the driving end of the motor (11) is fixedly sleeved with a rotating disc (26), the outer wall of the rotating disc (26) is uniformly embedded with a plurality of magnet plates, the magnet block and the magnet plate on the opposite side are magnetically the same, the outer wall of the annular pipe (19) is further fixed with a piston pipe two (31) which is located below each filter groove (16), the piston pipe two (31) is slidably provided with a piston plate two, the piston plate two and the inner wall of the piston pipe two (31) are fixedly connected with a telescopic spring, the outer wall of the piston plate two is fixed with a cross rod, the filter groove (16) is slidably penetrated with a sliding rod (18), the cross rod and the sliding rod (18) are fixedly connected with a vertical plate (32).

6. A PAC dosing system apparatus with precision metering as claimed in claim 1, wherein, The inner part of the holding tank (4) is designed as a tapered flow channel (33) which shrinks downward.

7. A PAC dosing system apparatus with precision metering as claimed in claim 1, wherein, The lower end of the holding tank (4) is in contact with the discharging disc (8), and the contact part is provided with an arc-shaped opening which is in contact with the outer wall of the discharging disc (8).

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