A high-efficiency sand removal process system and method for wastewater pre-sedimentation tanks in waterworks

Abstract

This invention relates to the field of wastewater treatment technology and discloses a high-efficiency sand removal process system and method for wastewater from the pre-sedimentation tank of a waterworks. The system includes: a pretreatment system for receiving pulse-discharged grit wastewater from the pre-sedimentation tank; a primary thickening device for initial sand-water separation of the grit wastewater; a sedimentation system for sedimentation of the grit wastewater; a secondary thickening device for further separation of the sedimented grit from the sedimentation system; and a sand removal system for final separation of the water-containing sand separated by the secondary thickening device. This invention integrates hydraulic cyclone, silt-sand classification, and internal circulation thickening technologies through a thickening-sedimentation-thickening-sand removal process, achieving stepwise separation and precise removal of silt and sand of all particle sizes (0.08-0.3mm). The removal rate of fine sand of all particle sizes is ≥90%, improving treatment quality. It solves long-standing problems in waterworks such as difficulty in removing fine sand, large load fluctuations, and equipment wear.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically to a high-efficiency sand removal process system and method for wastewater pre-sedimentation tanks in waterworks. Background Technology

[0002] Due to factors such as urban construction projects and municipal pipeline construction, the water treatment processes in my country's urban waterworks generally suffer from inadequate grit removal wastewater treatment facilities. However, there are few published reports on relevant grit removal wastewater treatment processes. Currently, the pre-sedimentation tanks in waterworks often experience intermittent sludge discharge and large hydraulic fluctuations, leading to unstable sludge-to-sludge ratios, easy sand entrapment, and easy sludge settling and clogging. This affects the efficiency of sand-water separation and limits the stable operation of subsequent treatment systems. Furthermore, grit removal wastewater is often directly discharged, posing environmental compliance risks. Summary of the Invention

[0003] The purpose of this invention is to provide a high-efficiency sand removal process system and method for wastewater in the pre-sedimentation tank of a waterworks, which solves the problems of low efficiency and poor effect of existing technologies in treating sand-sedimented wastewater.

[0004] This invention is achieved through the following technical solution: a high-efficiency sand removal process system for wastewater in the pre-sedimentation tank of a waterworks, comprising: The pretreatment system is used to receive the grit wastewater discharged in a pulse from the pre-sedimentation tank and transport it to the primary thickening unit. The primary concentration unit is used to perform preliminary sand-water separation of the grit wastewater and then transport the wastewater to the sedimentation system. A sedimentation system is used to settle grit wastewater. The sedimentation system is equipped with an inclined plate sedimentation tank and a thickening sedimentation tank. The water-containing sand separated by the primary thickening device is discharged into the thickening sedimentation tank, while the sand-containing water is discharged into the inclined plate sedimentation tank. The secondary thickening device is used to further separate the sedimented sand in the sedimentation system. The sand-containing water separated by the secondary thickening device is returned to the thickening sedimentation tank, while the water-containing sand is discharged into the sand removal system. The sand removal system is used for the final separation of the water-containing sand after separation by the secondary concentration unit.

[0005] To better realize the present invention, the sedimentation system further includes a sedimentation tank, wherein a baffle is provided in the middle of the sedimentation tank to divide the internal space of the sedimentation tank into the inclined plate sedimentation tank and the concentration sedimentation tank; an inlet is provided at one end of the inclined plate sedimentation tank near the baffle, which is connected to the drain end of the primary concentration device; a sand inlet is provided at one end of the concentration sedimentation tank near the baffle, which is connected to the sand discharge end of the primary concentration device; a drain is provided at one end of the inclined plate sedimentation tank away from the baffle; and a sand discharge is provided at one end of the concentration sedimentation tank away from the baffle.

[0006] To better realize the present invention, the sedimentation system further includes a sand discharge screw and a screw pump. The sand discharge screw is disposed at the bottom of the sedimentation tank and passes through the partition. The screw pump is drivenly connected to the sand discharge screw. The sand discharge screw transports the settled sand to the sand discharge port on the concentration sedimentation tank.

[0007] To better realize the present invention, the sedimentation system further includes a slurry pump, one end of which is connected to the sand discharge port of the thickening sedimentation tank, and the other end is connected to the water inlet of the secondary thickening device.

[0008] To better realize the present invention, the sedimentation system further includes a flushing pump, the output end of which is connected to the sedimentation tank and the mortar pump respectively.

[0009] To better realize the present invention, inclined plates are further installed on both sides of the partition, and the inclined plates are inclined to guide the water flow.

[0010] To better realize the present invention, a sludge discharge valve is further provided in the middle of the thickening sedimentation tank for discharging the sludge that is between sand and water in the thickening sedimentation tank.

[0011] To better realize the present invention, the pretreatment system further includes an integrated pump station and a slag removal and filtration station. The integrated pump station is used to store the pre-sedimentation tank discharge into the grit wastewater. The slag removal and filtration station is connected to the output end of the integrated pump station and the input end of the primary thickening device, respectively, and is used to filter out impurities from the grit wastewater.

[0012] To better realize the present invention, the sand removal system further includes a sand collecting hopper and a spiral sand discharger. The input end of the sand collecting hopper is connected to the sand discharge end of the secondary thickening device, and the input end of the spiral sand discharger is connected to the output end of the sand collecting hopper. The output end of the spiral sand discharger is higher than the input end, and the input end is provided with a drain outlet.

[0013] A method for efficient sand removal from wastewater in a pre-sedimentation tank of a waterworks includes: Step S1: Discharge the grit wastewater from the pre-sedimentation tank into the pretreatment system for pretreatment. At this time, the solids content of the grit wastewater is 0.2%. Step S2: The pretreated grit wastewater is introduced into a primary thickening device for preliminary separation to obtain water-containing sand and sand-containing water, wherein the solid content of the water-containing sand is increased to 2%-3%. Step S3: The water-containing sand and sand-containing water are introduced into the thickening sedimentation tank and the inclined plate sedimentation tank respectively to start sedimentation. The upper clear liquid is discharged to the next process, and the lower sand is discharged into the secondary thickening device. Step S4: The secondary thickening device begins to further separate the water-containing sand discharged from the sedimentation system. The resulting sand-containing water is returned to the thickening sedimentation tank for further sedimentation, while the resulting water-containing sand with a solid content of 10% is introduced into the sand removal system. Step S5: The sand removal system begins to perform final separation of the water-containing sand discharged from the secondary thickening unit and discharges all fine sand.

[0014] Compared with the prior art, the present invention has the following advantages and beneficial effects: (1) This invention achieves the step-by-step separation and precise removal of 0.08-0.3mm full-size silt and sand by sequentially performing a four-stage linkage of concentration-sedimentation-concentration-sand extraction, integrating hydraulic cyclone, mud and sand classification and separation and internal circulation concentration technology, with a full-size fine sand removal rate of ≥90%, which greatly improves the treatment quality; (2) This invention solves the long-standing problems of fine sand removal, large load fluctuations, and equipment wear in waterworks; it realizes standardized modular design and unattended intelligent control, thereby improving the overall processing efficiency. (3) Compared with traditional sedimentation tanks and gravity sedimentation equipment, this invention occupies about 100㎡, saving 75% of land, with a short process and high degree of automation. Compared with mining hydrocyclone technology, this system is more suitable for the characteristics of low concentration and high fluctuation of mud and sand in urban water plants, achieving effective separation of fine particle size, and providing an engineering solution for the "blank technology" in this field in China. (4) By setting up a pretreatment system, the present invention can solve the instability caused by the pulsed effluent of the pre-sedimentation tank, and at the same time filter out the impurities in the grit wastewater to prevent blockage in subsequent treatment. (5) This invention is applicable to the renovation of existing water plants and the intensive construction of new water plants. It can be quickly replicated and promoted. It can reduce the initial construction cost by about RMB3 million and save 300,000 m³ of water per year. It significantly reduces equipment wear and environmental risks, improves the safety of water plant operation, and has a demonstrative effect on water conservation, carbon reduction and green environmental protection in the industry. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the installation layout structure of the present invention.

[0016] Figure 2 This is a simplified schematic diagram of the overall structure of the present invention.

[0017] Figure 3 This is a schematic diagram of the precipitation system.

[0018] Figure 4 This is a schematic diagram of a sand-discharging screw pump.

[0019] The components are as follows: 10-Pretreatment system; 101-Integrated pump station; 102-Slag removal and filtration station; 20-Primary thickening device; 30-Sedimentation system; 31-Inclined plate sedimentation tank; 32-Thickening sedimentation tank; 301-Sedimentation tank; 302-Baffle plate; 303-Inclined plate; 304-Support frame; 305-Sand discharge screw; 306-Screw pump; 307-Sludge discharge valve; 308-Flushing pump; 309-Mortar pump; 40-Secondary thickening device; 50-Sand removal system; 501-Sand collection hopper; 502-Screw sand discharger. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances. Example 1:

[0022] This embodiment provides a high-efficiency sand removal process system for wastewater in the pre-sedimentation tank of a waterworks, specifically as follows: Figures 1-2 As shown, it includes: The pretreatment system 10 is used to receive the grit wastewater discharged in a pulse from the pre-sedimentation tank and transport it to the primary thickening unit 20. It has an effective volume of 12m³ and is located at the rear end of the sludge discharge main pipe of the pre-sedimentation tank. It is equipped with an electric throttle valve, which is controlled by a PLC to balance the concentration of grit wastewater and ensure the stability of the grit removal process load. The primary thickening unit 20 is used to perform preliminary sand-water separation on the grit wastewater and transport it to the sedimentation system 30 respectively; through internal and external swirling action, the heavy sand and mud are separated from the light mud, with a thickening ratio of 1:0.3; The sedimentation system 30 is used to settle the grit wastewater. The sedimentation system 30 is equipped with an inclined plate sedimentation tank 31 and a thickening sedimentation tank 32. The water-containing sand separated by the primary thickening device 20 is discharged into the thickening sedimentation tank 32, while the sand-containing water is discharged into the inclined plate sedimentation tank 31. The secondary thickening device 40 is used to further separate the sediment in the sedimentation system 30. The sand-containing water separated by the secondary thickening device 40 is returned to the thickening sedimentation tank 32, while the water-containing sand is discharged into the sand removal system 50; the thickening ratio is 1:0.05. The sand removal system 50 is used for the final separation of the water-containing sand after separation by the secondary thickening device 40; Both the primary concentration unit 20 and the secondary concentration unit 40 employ hydrocyclones.

[0023] Its advantages are: (1) Through the four-stage linkage of concentration-sedimentation-concentration-sand removal, the separation and precise removal of all particle size mud and sand can be achieved step by step; (2) It solves the long-standing problems of fine sand removal, large load fluctuation and equipment wear in waterworks; it realizes standardized module design and unattended intelligent control; (3) Compared with traditional grit chambers and gravity sedimentation equipment, this invention has a small footprint, short process and high degree of automation; compared with mining hydrocyclone technology, this system is more suitable for the characteristics of low concentration and high fluctuation mud and sand in urban waterworks, and achieves effective separation of fine particle size, providing an engineering solution for the "blank technology" in this field in China; (4) It is suitable for the renovation of existing waterworks and the intensive construction of new waterworks, and can be quickly replicated and promoted; it can reduce the initial construction cost by about RMB3 million and save RMB300,000 m³ of water per year; it significantly reduces equipment wear and environmental risks, improves the safety of waterworks operation, and has a demonstration effect on water conservation, carbon reduction and green environmental protection in the industry. Example 2:

[0024] This embodiment further expands the precipitation system 30 based on the above embodiments, specifically as follows: Figures 2-4 As shown, the sedimentation system 30 includes a sedimentation tank 301, with multiple support frames 304 on the outside of the sedimentation tank 301 to maintain its stability. A partition 302 is provided in the middle of the sedimentation tank 301 to divide the internal space of the sedimentation tank 301 (the top is completely partitioned, forming a water-dividing weir) to form the inclined plate sedimentation tank 31 and the concentration sedimentation tank 32. An inlet is provided on the inclined plate sedimentation tank 31 near the partition 302, which is connected to the drain end of the primary concentration device 20. A sand inlet is provided on the concentration sedimentation tank 32 near the partition 302, which is connected to the sand discharge end of the primary concentration device 20. A drain outlet is provided on the inclined plate sedimentation tank 31 away from the partition 302, and a sand discharge outlet is provided on the concentration sedimentation tank 32 away from the partition 302. The sedimentation system 30 has an overall processing flow rate of 30 m³ / h, the inclined plate sedimentation tank 31 has a volume of 10 m³, the concentration sedimentation tank 32 has a volume of 5 m³, the surface loading rate of the inclined plate sedimentation tank 31 is 4.69 m³ / (㎡·h), and the upward flow velocity is 1.3 mm / s.

[0025] After the primary thickening device 20 separates the grit-laden wastewater, the grit-laden water is discharged into the inclined plate sedimentation tank 31, and the water-laden sand is discharged into the thickening sedimentation tank 32. At the same time, the grit-laden water discharged from the secondary thickening device 40 is also returned to the thickening sedimentation tank 32 and settles together. As new wastewater continues to enter, the upper layer of relatively clear grit-laden water overflows the weir (top of the partition 302) and flows into the inclined plate sedimentation tank 31, while the lower layer of settled sand is discharged into the secondary thickening device 40. The grit-laden water introduced by the primary thickening device 20 and the grit-laden water flowing into the thickening sedimentation tank 32 both settle in the inclined plate sedimentation tank 31. At this time, the upper layer in the inclined plate sedimentation tank 31 is basically clear liquid without sand, which is discharged through the drain outlet on the inclined plate sedimentation tank 31, while a small amount of grit is generated at the bottom.

[0026] Since the sedimentation system 30 is equipped with an inclined plate sedimentation tank 31 and a thickening sedimentation tank 32, the sand-containing wastewater can be graded and settled in the sedimentation system 30. At the same time, the wastewater separated at the secondary thickening device 40 is returned to the thickening sedimentation tank 32 for sedimentation. The upper layer of wastewater in the thickening sedimentation tank 32 is introduced into the inclined plate sedimentation tank 31 for further sedimentation, thus constructing an internal circulation thickening scheme, which greatly improves the sand-water separation effect.

[0027] Furthermore, the sedimentation system 30 also includes a sand discharge screw 305 and a screw pump 306. The sand discharge screw 305 is located at the bottom of the sedimentation tank 301 and passes through the partition 302. The screw pump 306 is connected to the sand discharge screw 305 in a driving connection. The sand discharge screw 305 transports the settled sand to the sand discharge port on the concentration sedimentation tank 32.

[0028] Since the sedimentation tank 301 has a circular cross-section, the sedimented sand will all collect at the sand discharge screw 305. The sand discharge screw 305 is driven by the screw pump 306, which will transport the collected sand to the sand discharge port, so that the fine sand in the inclined plate sedimentation tank 31 and the thickening sedimentation tank 32 can be discharged periodically without disturbing the sedimentation of the middle and upper layers of wastewater and without affecting the sedimentation effect.

[0029] Furthermore, the sedimentation system 30 also includes a slurry pump 309, one end of which is connected to the sand discharge port of the thickening sedimentation tank 32, and the other end is connected to the water inlet of the secondary thickening device 40.

[0030] Two mortar pumps 309 are connected in parallel. One can be used daily while the other is on standby. When the mortar pump 309 is started, it will suck up the fine sand accumulated at the sand discharge port and transfer it to the secondary thickening device 40.

[0031] Furthermore, the sedimentation system 30 also includes a flushing pump 308, the output of which is connected to the sedimentation tank 301 and the mortar pump 309 respectively.

[0032] Two flushing pumps 308 are connected in parallel. One can be used daily, and the other can be kept as a backup. The flushing pump 308 is connected to the site's tap water pipe. When started, tap water is fed into the sedimentation tank 301 and / or the mortar pump 309. The tap water is distributed into the sedimentation tank 301 at multiple points, which can work with the sand discharge screw 305 to periodically and lightly stir the wastewater in the inclined plate sedimentation tank 31 and the thickening sedimentation tank 32 to promote the separation of sand and fine mud. The tap water is supplied to the mortar pump 309 for systematic cleaning operations.

[0033] Furthermore, inclined plates 303 are installed on both sides of the partition 302. The inclined plates 303 are inclined to guide the water flow.

[0034] The inclined plate 303 serves two purposes: firstly, it guides the incoming water flow, allowing it to circulate in the inclined plate sedimentation tank 31 and the thickening sedimentation tank 32; secondly, it can withstand the impact of the water flow and disperse the water flow, preventing it from impacting the fine sand that has already settled at the bottom.

[0035] Furthermore, a sludge discharge valve 307 is provided in the middle of the thickening sedimentation tank 32 for discharging sludge that is between sand and water in the thickening sedimentation tank 32.

[0036] Because the solids content in the thickening sedimentation tank 32 is higher, there will be sludge sedimentation in the middle layer. The sludge discharge valve 307 needs to be opened periodically to automatically discharge the sludge under gravity. The clear water discharged from the mixed inclined plate sedimentation tank 31 is then used for subsequent water treatment.

[0037] The other parts of this embodiment are the same as those in the above embodiments, and will not be described again. Example 3:

[0038] This embodiment further expands upon the pretreatment system 10 and the sand removal system 50 based on the above embodiments, specifically as follows: Figure 2 As shown, the pretreatment system 10 includes an integrated pump station 101 and a slag removal and filtration station 102. The integrated pump station 101 is arranged in a submerged manner and is used to store the pre-sedimentation tank discharge into the grit wastewater. The slag removal and filtration station 102 is connected to the output end of the integrated pump station 101 and the input end of the primary thickening device 20, respectively, and is used to filter out impurities from the grit wastewater.

[0039] Since the wastewater discharged from the pre-sedimentation tank to the grit chamber is pulsed, an integrated pump station 101 is designed to collect it, so that the wastewater supplied to the primary thickening unit 20 is continuous and stable, eliminating the instability of pulsed discharge and improving the reliability of the overall system. The sludge removal and filtration station 102 is designed to filter out larger debris such as branches and leaves from the wastewater, and only water, mud and sand are supplied to the primary thickening unit 20 to avoid subsequent blockage.

[0040] Furthermore, the sand removal system 50 includes a sand collection hopper 501 and a spiral sand discharger 502. The input end of the sand collection hopper 501 is connected to the sand discharge end of the secondary thickening device 40, and the input end of the spiral sand discharger 502 is connected to the output end of the sand collection hopper 501. The output end of the spiral sand discharger 502 is higher than the input end, and the input end is provided with a drain outlet.

[0041] The sand collection hopper 501 receives the sand discharged from the secondary thickening unit 40 and then flows into the input end of the spiral sand discharger 502. When the spiral sand discharger 502 is working, it discharges the sand obliquely upwards. At this time, water will flow to the input end of the sand collection hopper 501 under the action of gravity and flow out from the drain outlet at the input end. This part of the water will then enter the thickening sedimentation tank 32 for further sedimentation (not shown in the figure).

[0042] The other parts of this embodiment are the same as those in the above embodiments, and will not be described again. Example 4:

[0043] This embodiment provides a method for efficient sand removal from wastewater in a pre-sedimentation tank of a waterworks. Based on the sand removal process system provided in the above embodiment, it includes: Step S1: Discharge the grit wastewater from the pre-sedimentation tank into the pretreatment system 10 for pretreatment; specifically: Step S11: The integrated pump station 101 receives the sand-containing wastewater from the pre-sedimentation tank, stores a certain amount in the integrated pump station 101, and then discharges it. The discharge volume is equivalent to the drainage volume of the pre-sedimentation tank, ensuring that the integrated pump station 101 can continuously and stably discharge wastewater. In step S12, the wastewater discharged from the integrated pump station 101 passes through the slag removal and filtration station 102, where large impurities in the wastewater are filtered out, and then discharged to the primary concentration unit 20. At this time, the solid content of the grit wastewater is 0.2%. Step S2: The pretreated grit wastewater is introduced into the primary thickening unit 20 for preliminary separation to obtain water-containing sand and sand-containing water, wherein the solid content of the water-containing sand is increased to 2%-3%. Step S3: The water-containing sand and sand-containing water are respectively introduced into the thickening sedimentation tank 32 and the inclined plate sedimentation tank 31 to begin sedimentation. The upper clear liquid is discharged to the next process, while the lower sand is discharged into the secondary thickening device 40; Specifically: Step S31: The wastewater in the thickening sedimentation tank 32 begins to settle, and the upper layer of wastewater is turned over into the inclined plate sedimentation tank 31 through the top of the baffle 302. Step S32: After the wastewater settles in the inclined plate sedimentation tank 31, the supernatant is discharged. Step S33: When the screw pump 306 is running, it rotates for 30 seconds and stops for 40 seconds, with a speed of 2-6 rpm. It collects the sand settled in the inclined plate sedimentation tank 31 and the thickening sedimentation tank 32 to the sand discharge port, with a conveying capacity of 0.5 m³ / h. Step S34: The mortar pump 309 continuously transports the sand from the sand discharge port to the secondary thickening unit 40; Step S35: The mud discharge valve 307 is activated periodically to discharge the mud. In step S4, the secondary thickening device 40 begins to further separate the water-containing sand discharged from the sedimentation system 30. The resulting sand-containing water is returned to the thickening sedimentation tank 32 for further sedimentation, while the resulting water-containing sand with a solid content of 10% of the pretreatment system is introduced into the sand removal system 50. Step S5: The sand removal system 50 begins to perform final separation of the water-containing sand discharged from the secondary thickening unit 40 and discharges all fine sand. The effective volume of the sand collection hopper 501 is 0.8 m³. The spiral sand discharger 502 operates intermittently, rotating for 30 seconds and stopping for 4 minutes.

[0044] This method reduced the sand content in the effluent from 1 g / L before the rectification to 0.04 g / L, with an overall sand removal efficiency of over 90%.

[0045] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A high-efficiency sand removal process system for wastewater pre-sedimentation tanks in waterworks, characterized in that, include: The pretreatment system (10) is used to receive the grit wastewater discharged in the pre-sedimentation tank in a pulse and to transport it to the primary thickening unit (20). A primary concentration unit (20) is used to perform preliminary sand-water separation on the grit wastewater and then transport it to the sedimentation system (30). The sedimentation system (30) is used to settle the grit wastewater. The sedimentation system (30) is equipped with an inclined plate sedimentation tank (31) and a thickening sedimentation tank (32). The water-containing sand separated by the primary thickening device (20) is discharged into the thickening sedimentation tank (32), while the sand-containing water is discharged into the inclined plate sedimentation tank (31). The secondary thickening device (40) is used to further separate the sediment in the sedimentation system (30). The sand-containing water separated by the secondary thickening device (40) is returned to the thickening sedimentation tank (32), while the water-containing sand is discharged into the sand removal system (50). The sand removal system (50) is used to perform final separation of the water-containing sand after separation by the secondary thickening device (40).

2. The efficient sand removal process system for pre-sedimentation tank wastewater in a waterworks according to claim 1, characterized in that: The sedimentation system (30) includes a sedimentation tank (301), and a partition (302) is provided in the middle of the sedimentation tank (301) to divide the internal space of the sedimentation tank (301) into the inclined plate sedimentation tank (31) and the concentration sedimentation tank (32). The inclined plate sedimentation tank (31) is provided with an inlet at one end near the partition (302) and is connected to the drain end of the primary concentration device (20). The concentration sedimentation tank (32) is provided with a sand inlet at one end near the partition (302) and is connected to the sand discharge end of the primary concentration device (20). The inclined plate sedimentation tank (31) is provided with a drain at one end away from the partition (302), and the concentration sedimentation tank (32) is provided with a sand discharge outlet at one end away from the partition (302).

3. The efficient sand removal process system for pre-sedimentation tank wastewater in a waterworks according to claim 2, characterized in that: The sedimentation system (30) also includes a sand discharge screw (305) and a screw pump (306). The sand discharge screw (305) is located at the bottom of the sedimentation tank (301) and passes through the partition (302). The screw pump (306) is connected to the sand discharge screw (305) in a driving connection. The sand discharge screw (305) transports the sediment to the sand discharge port on the concentration sedimentation tank (32).

4. The efficient sand removal process system for pre-sedimentation tank wastewater in a waterworks according to claim 3, characterized in that: The sedimentation system (30) also includes a slurry pump (309), one end of which is connected to the sand discharge port of the thickening sedimentation tank (32), and the other end is connected to the water inlet of the secondary thickening device (40).

5. The efficient sand removal process system for pre-sedimentation tank wastewater in a waterworks according to claim 4, characterized in that: The sedimentation system (30) also includes a flushing pump (308), the output of which is connected to the sedimentation tank (301) and the mortar pump (309) respectively.

6. The efficient sand removal process system for pre-sedimentation tank wastewater in a waterworks according to claim 2, characterized in that: Inclined plates (303) are installed on both sides of the partition (302). The inclined plates (303) are set at an angle to guide the water flow.

7. The efficient sand removal process system for pre-sedimentation tank wastewater in a waterworks according to claim 2, characterized in that: The thickening sedimentation tank (32) is equipped with a sludge discharge valve (307) in the middle, which is used to discharge the sludge between sand and water in the thickening sedimentation tank (32).

8. A high-efficiency sand removal process system for wastewater pre-sedimentation tanks in waterworks according to any one of claims 1-7, characterized in that: The pretreatment system (10) includes an integrated pump station (101) and a slag removal and filtration station (102). The integrated pump station (101) is used to store the pre-sedimentation tank discharge into the sedimentation wastewater. The slag removal and filtration station (102) is connected to the output end of the integrated pump station (101) and the input end of the primary thickening device (20) respectively, and is used to filter out impurities in the sedimentation wastewater.

9. A high-efficiency sand removal process system for pre-sedimentation tank wastewater in a waterworks according to any one of claims 1-7, characterized in that: The sand removal system (50) includes a sand collection hopper (501) and a spiral sand discharger (502). The input end of the sand collection hopper (501) is connected to the sand discharge end of the secondary thickening device (40). The input end of the spiral sand discharger (502) is connected to the output end of the sand collection hopper (501). The output end of the spiral sand discharger (502) is higher than the input end, and the input end is provided with a drain outlet.

10. A method for efficient sand removal from wastewater in a pre-sedimentation tank of a waterworks, based on the process system described in any one of claims 1-9, characterized in that, include: Step S1: Discharge the grit wastewater from the pre-sedimentation tank into the pretreatment system (10) for pretreatment. At this time, the solid content of the grit wastewater is 0.2%. Step S2: The pretreated grit wastewater is introduced into the primary thickening device (20) to perform preliminary separation of the grit wastewater, obtaining water-containing sand and sand-containing water, wherein the solid content of the water-containing sand is increased to 2%-3%; Step S3: The water-containing sand and sand-containing water are introduced into the thickening sedimentation tank (32) and the inclined plate sedimentation tank (31) respectively to start sedimentation. The upper clear liquid is discharged to the next process, and the lower sand is discharged into the secondary thickening device (40). Step S4: The secondary thickening device (40) begins to further separate the water-containing sand discharged from the sedimentation system (30). The resulting sand-containing water is returned to the thickening sedimentation tank (32) for further sedimentation, while the resulting water-containing sand with a solid content of 10% is introduced into the sand removal system (50). Step S5: The sand removal system (50) begins to perform final separation of the water-containing sand discharged from the secondary thickening unit (40) and discharges all fine sand.

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