System fine sand secondary recovery and sludge concentration control device and sewage treatment system

Abstract

The utility model relates to the technical field of sewage treatment, and provides a fine sand secondary recovery and sludge concentration control device of a system and a sewage treatment system. The fine sand secondary recovery and sludge concentration control device of the system comprises a sludge inlet buffer area; the rotational flow sand collecting area is communicated with the inlet mud buffer area through a mud inlet pipeline to form a cylindrical rotational flow space, the mud inlet pipeline extends in the tangential direction of the rotational flow space, a fine sand settling area is formed at the bottom of the rotational flow space and communicated to the outside through a recycled sand outlet, and a sand collecting area outlet is formed in the top of the rotational flow space; the scum collecting area is communicated with an outlet of the sand collecting area and is communicated to the outside through a scum discharging opening; the sludge secondary settling area is communicated with the scum collecting area; and the sludge secondary settling zone is communicated with the overflow sludge discharge zone through an overflow structure. According to the sand-adding high-efficiency sedimentation tank, fine sand in discharged substances is recycled, and the discharge control of sludge concentration is also realized, so that the problems that the sand loss of a traditional sand-adding high-efficiency sedimentation tank is too high and the water content of residual discharged sludge is too high are solved.

Description

Technical Field

[0001] The utility model relates to the technical field of sewage treatment, in particular to a system fine sand secondary recovery and sludge concentration control device and a sewage treatment system. Background Art

[0002] The sand-added high-efficiency sedimentation tank is based on the coagulation, flocculation and sedimentation technology of the high-speed clarifier. Sand media is added through the coagulation and flocculation section to work together with polymer flocculants (PAC) and polymer coagulant aids (PAM) to increase the probability of flocculation particle collision, strengthen the coagulation and flocculation reaction effect, make it easier to capture destabilized suspended matter in the water, form a larger density of alum flowers, and achieve high-efficiency mud-water separation and sedimentation.

[0003] As attached Figure 1 As shown, the raw water to be purified passes through the coagulation contact tank, coagulation and sand addition tank, flocculation tank, and inclined plate sedimentation tank in the sand-added high-efficiency sedimentation tank in sequence, resulting in purified effluent. The conventional sand and sludge mixture at the bottom of the inclined plate sedimentation tank is pumped into the hydrocyclone via a circulation pump. Most of the fine sand flows through the lower sediment return pipe into the coagulation and sand addition tank. The remaining sludge flows through the upper pipe to the residual sludge tank and is then discharged into the thickening tank. The stable sand media injection and recovery system of the hydrocyclone ensures faster, more efficient, and more stable TP and SS treatment.

[0004] To maintain a stable concentration of sludge and fine sand in the sedimentation tank, the circulating pump must be continuously running, and the hydrocyclone must operate 24 hours a day. The sludge discharge rate of a traditional hydrocyclone is determined by the flow rate of the circulating pump. In actual operation, relying solely on the frequency conversion control flow rate of the circulating pump cannot accurately control the daily sludge discharge rate. At the same time, the sludge concentration in the sedimentation tank cannot be controlled. If the circulating pump is turned on too high, the moisture content of the residual sludge is too high. If the circulating pump is turned on too low, the speed in the hydrocyclone is low, the silt and sand separation effect is poor, and a lot of sand enters the residual sludge, resulting in great waste. The difficulty in controlling the return flow ratio during operation is a major challenge in high-efficiency sedimentation tanks with sand addition.

[0005] We also discovered that even in a steady-state system, the fine sand content in the upper sludge was still relatively high, resulting in significant sand loss. The daily fine sand replenishment required a level of 4-6 mg / L (influent volume), resulting in high operating costs. Furthermore, the sludge had a high moisture content, approximately 99.4-99.8%, which significantly impacted subsequent sludge disposal and reduced desludging efficiency.

[0006] At the same time, the discharge of a large amount of fine sand will cause serious wear and tear on the subsequent sludge deep treatment system equipment of the sewage treatment plant, making the equipment easily damaged. Utility Model Content

[0007] The utility model provides a system fine sand secondary recovery and sludge concentration control device and a sewage treatment system, which are used to solve the defects in the existing technology and achieve the following technical effects: the discharge discharged from the sewage treatment system can be treated. On the one hand, the fine sand in the discharge can be recycled and utilized. On the other hand, the discharge concentration of the sludge can be controlled, thereby solving the problems of excessive sand loss in traditional sand-added high-efficiency sedimentation tanks and excessively high water content of the discharged residual sludge.

[0008] The system fine sand secondary recovery and sludge concentration control device according to the first embodiment of the present utility model includes:

[0009] a mud inlet buffer area having a mud inlet connected to a discharge outlet of the sewage treatment system for receiving discharge from the system;

[0010] A cyclone sand collection area is connected to the sludge inlet buffer area through a sludge inlet pipe, and a cylindrical cyclone space is formed inside the cyclone sand collection area. The sludge inlet pipe extends in a tangential direction of the cyclone space so that the discharge forms a cyclone. A fine sand sedimentation area is formed at the bottom of the cyclone space, and the fine sand sedimentation area is connected to the outside through a recovered sand outlet. A sand collection area outlet is formed at the top of the cyclone space. Under the action of the cyclone, the fine sand in the discharge falls into the fine sand sedimentation area, and the scum and sludge in the discharge are discharged through the sand collection area outlet.

[0011] A scum collection area is connected to the sand collection area outlet of the cyclone sand collection area, and the scum collection area is connected to the outside through a scum discharge port;

[0012] a sludge secondary sedimentation zone, connected to the sludge collection zone through a sludge through hole, and the sludge in the sludge collection zone enters the sludge secondary sedimentation zone through the sludge through hole;

[0013] The overflow mud discharge area is provided with an overflow structure on the top of the overflow mud discharge area. The sludge secondary sedimentation area is connected with the overflow mud discharge area through the overflow structure, and the overflow mud discharge area is connected to the outside through the sludge discharge port.

[0014] According to one embodiment of the present invention, a first regulating valve with adjustable opening is provided at the recovered sand outlet, and a second regulating valve with adjustable opening is provided at the sludge discharge outlet.

[0015] According to one embodiment of the present invention, the cyclone sand collection area further includes a flow guiding center cylinder, the flow guiding center cylinder extends along the central axis of the cyclone space, and the central axes of the two coincide with each other;

[0016] In the height direction of the vortex space, the flow guide central cylinder is respectively arranged opposite to the mud inlet pipe and the sand collection area outlet.

[0017] According to one embodiment of the present invention, the cyclone sand collection area further includes a guide reflector plate, the guide reflector plate is truncated cone-shaped and its central axis coincides with the central axis of the guide central tube, and the end of the guide reflector plate with a smaller diameter is connected to the bottom end of the guide central tube;

[0018] In the height direction of the cyclone space, the guide reflector is located between the mud inlet pipe and the fine sand precipitation area.

[0019] According to one embodiment of the present utility model, a fine sand discharge area is provided outside the fine sand sedimentation area, and the fine sand discharge area is respectively connected to the fine sand sedimentation area and the sludge secondary sedimentation area, and the recovered sand outlet is provided on the side wall of the fine sand discharge area.

[0020] According to one embodiment of the present invention, a first sand guide slope with a gradually decreasing height is provided at the bottom of the system fine sand secondary recovery and sludge concentration control device in the direction from the fine sand sedimentation area to the fine sand discharge area;

[0021] And / or, in the direction from the sludge secondary sedimentation zone to the fine sand discharge zone, a second sand guide slope with a gradually decreasing height is provided at the bottom of the system fine sand secondary recovery and sludge concentration control device.

[0022] According to one embodiment of the present invention, the sludge passing hole is provided at the bottom of the scum collecting area.

[0023] According to one embodiment of the present invention, the sludge inlet buffer area is connected to the sludge secondary sedimentation area through an overflow hole provided on the top thereof.

[0024] According to one embodiment of the present invention, the overflow structure is an overflow weir arranged at the top of the overflow mud discharge area, and the overflow weir is sawtooth-shaped and extends along the top wall of the overflow mud discharge area.

[0025] According to the second embodiment of the present invention, the sewage treatment system includes:

[0026] The system fine sand secondary recovery and sludge concentration control device as described in the embodiment of the first aspect of the utility model;

[0027] The coagulation contact tank, coagulation sand adding tank, flocculation tank and inclined plate sedimentation tank are connected in sequence. The inclined plate sedimentation tank is connected to the hydrocyclone through the purified water outlet. The sediment return pipe of the hydrocyclone is connected to the coagulation sand adding tank, and the residual sludge discharge pipe of the hydrocyclone is connected to the mud inlet of the system fine sand secondary recovery and sludge concentration control device, and the recovered sand outlet of the system fine sand secondary recovery and sludge concentration control device is also connected to the coagulation sand adding tank.

[0028] The utility model provides a system fine sand secondary recovery and sludge concentration control device, which can treat the discharge discharged from the sewage treatment system. On the one hand, it can realize the recovery and utilization of the fine sand in the discharge, and on the other hand, it can also realize the discharge control of the sludge concentration, thereby solving the problems of excessive sand loss in traditional sand-added high-efficiency sedimentation tanks and excessively high moisture content of the discharged residual sludge.

[0029] Furthermore, compared with the related art, the present invention has at least the following additional advantages.

[0030] (1) Energy-saving operation and low failure rate: This device uses the natural head difference of the original system as the power source and does not require additional electrical energy to drive it. Therefore, the operating cost is extremely low, energy-saving and environmentally friendly. In addition, there are no complex mechanical moving parts inside the device, and the structure is simple and reliable, which reduces the possibility of failure and reduces maintenance costs.

[0031] (2) Efficient recovery of fine sand: The unique design enables secondary recovery of fine sand, reducing the amount of fine sand required to be replenished daily from 4-6 mg / L to 2-3 mg / L, thereby reducing the consumption of fine sand and saving operating costs.

[0032] (3) Good sludge concentration effect: This device can concentrate the system sludge, reducing the moisture content of the discharged residual sludge from 99.2-99.6% to 98-99%, thereby increasing the solid content of the residual sludge and reducing the burden of subsequent sludge treatment.

[0033] (4) Improve the performance of sedimentation tank: This device can increase the concentration of sludge in the sand-added high-efficiency sedimentation tank, enhance the sedimentation tank's ability to resist the impact of suspended matter, and improve the system's processing capacity and effluent water quality.

[0034] (5) Reduce equipment wear: By effectively recovering fine sand, the content of fine sand in the discharged residual sludge is reduced, the wear of subsequent sludge treatment system equipment is reduced, and the service life of the equipment is extended.

[0035] (6) System optimization: The proportion of fine sand in the sedimentation tank was increased from 2% to 4% of the total volume of the sedimentation tank, which accelerated the sedimentation rate of flocculent sludge in the system and thus improved the effluent water quality standard. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0037] Figure 1 It is a structural diagram of a sewage treatment system provided by relevant technology.

[0038] Figure 2 It is a structural diagram of the system fine sand secondary recovery and sludge concentration control device provided by the utility model.

[0039] Figure 3 It is along Figure 2 Schematic diagram of the cross-sectional structure along line AA.

[0040] Figure 4 It is along Figure 2 Schematic diagram of the cross-sectional structure along the BB line.

[0041] Figure 5 The utility model is a schematic diagram of the cross-sectional structure of the cyclone sand collection area of the system fine sand secondary recovery and sludge concentration control device provided by the utility model.

[0042] Figure 6 It is a schematic diagram of the steps of the control method of the system fine sand secondary recovery and sludge concentration control device provided by the utility model.

[0043] Figure 7 It is a structural diagram of the sewage treatment system provided by the utility model.

[0044] Figure 8 It is a structural diagram of the electronic equipment provided by the utility model.

[0045] Reference numerals:

[0046] 1. Raw water; 2. Coagulation contact tank; 3. Coagulation sand adding tank; 4. Flocculation tank; 5. Inclined plate sedimentation tank; 6. Purified effluent; 7. Hydrocyclone; 8. Sediment return pipe; 9. Residual sludge discharge pipe; 10. System fine sand secondary recovery and sludge concentration control device; 11. Sediment secondary recovery pipe;

[0047] 20. Box; 21. Mud inlet; 22. Mud inlet buffer area; 23. Cyclone sand collection area; 24. Scum collection area; 25. Sludge secondary sedimentation area; 26. Overflow mud discharge area; 27. Sludge discharge port; 28. Recovered sand outlet; 29. Scum discharge port;

[0048] 30. Sand collection shell; 31. Sand collection area entrance; 32. Water inlet diversion area; 33. Swirl reflection area; 34. Fine sand sedimentation area; 35. Swirl separation layer; 36. Mud discharge stabilization layer; 37. Sand collection area outlet; 38. Fine sand discharge area; 41. Mud inlet pipe; 42. Diversion center tube; 43. Diversion reflection plate; 44. Bottom connecting ring;

[0049] 51. First regulating valve; 52. Second regulating valve; 53. Residual sludge discharge flowmeter; 54. Third regulating valve; 55. Sludge through hole; 56. Overflow structure; 57. Overflow hole. DETAILED DESCRIPTION

[0050] To make the purpose, technical solutions, and advantages of the present invention more clear, the following will be combined with the accompanying drawings to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0051] The following describes, with reference to the accompanying drawings, a system fine sand secondary recovery and sludge concentration control device, a control method for the system fine sand secondary recovery and sludge concentration control device, and a sewage treatment system having the system fine sand secondary recovery and sludge concentration control device, provided by the present invention. It should first be explained that the system fine sand secondary recovery and sludge concentration control device of the present invention is used to treat a mixture of sludge, scum, and fine sand discharged from a sewage treatment system. The device can, on the one hand, achieve the recovery of fine sand, and, on the other hand, achieve controllable concentration of sludge to facilitate subsequent sludge treatment processes.

[0052] like Figures 2 to 7 As shown, the system fine sand secondary recovery and sludge concentration control device 10 according to the embodiment of the first aspect of the utility model includes a mud inlet buffer area 22, a cyclone sand collection area 23, a scum collection area 24, a sludge secondary sedimentation area 25 and an overflow mud discharge area 26 connected in sequence.

[0053] The mud inlet buffer area 22 has a mud inlet 21 , which is connected to the discharge port of the sewage treatment system for receiving the discharge of the system.

[0054] The cyclone sand collecting area 23 is connected to the mud inlet buffer area 22 through the mud inlet pipe 41, and a cylindrical cyclone space is formed inside the cyclone sand collecting area 23. The mud inlet pipe 41 extends along the tangential direction of the cyclone space so that the discharge forms a cyclone. A fine sand sedimentation area 34 is formed at the bottom of the cyclone space, and the fine sand sedimentation area 34 is connected to the outside through the recovered sand outlet 28; a sand collecting area outlet 37 is formed at the top of the cyclone space, wherein, under the action of the cyclone, the fine sand in the discharge falls into the fine sand sedimentation area 34, and the scum and sludge in the discharge are discharged through the sand collecting area outlet 37.

[0055] The sludge collection area 24 is connected to the sand collection area outlet 37 of the cyclone sand collection area 23, and the sludge collection area 24 is connected to the outside through the sludge discharge port 29; the sludge secondary sedimentation area 25 is connected to the sludge collection area 24 through the sludge through hole 55, and the sludge in the sludge collection area 24 enters the sludge secondary sedimentation area 25 through the sludge through hole 55; an overflow structure 56 is provided at the top of the overflow mud discharge area 26, and the sludge secondary sedimentation area 25 is connected to the overflow mud discharge area 26 through the overflow structure 56, and the overflow mud discharge area 26 is connected to the outside through the sludge discharge port 27.

[0056] For ease of understanding, the specific structure and working principle of each component of the device of the present invention will be described in sequence below. It can be understood that the system fine sand secondary recovery and sludge concentration control device 10 is a polyhedral box 20, which has various functional areas formed inside.

[0057] like Figure 2 As shown, the sludge buffer 22 has a sludge inlet 21, which is directly connected to the discharge port of the sewage treatment system and is used to receive excess sludge discharged from the system. It can be understood that the function of the sludge buffer 22 is to receive excess sludge from the sewage treatment system, which contains fine sand, scum, and other impurities. Thus, the sludge buffer 22 can effectively control the flow of sludge, allowing it to smoothly enter the next treatment stage.

[0058] The cyclonic sand collection area 23 forms a cylindrical cyclonic space within it. The sludge inlet conduit 41 is arranged tangentially to the cyclonic space, creating a swirling flow upon entry. Under the influence of the cyclonic flow, the denser fine sand particles sink to the bottom fine sand settling area 34 due to centrifugal force, while the less dense scum and excess sludge rise with the water flow and are discharged from the sand collection area outlet 37. Thus, the cyclonic sand collection area 23 effectively separates fine sand from scum and excess sludge.

[0059] The scum collection area 24 is connected to the sand collection area outlet 37 of the cyclone sand collection area 23, and discharges the scum out of the device through the scum discharge port 29. It will be appreciated that the scum collection area 24 is used to collect scum material that rises with the water flow and discharge it through the scum discharge port 29. In this way, the scum collection area 24 ensures that the scum does not interfere with subsequent processing, ensuring the purity of the recovered fine sand.

[0060] The secondary sludge settling zone 25 is connected to the scum collection zone 24 via sludge passage holes 55. Sludge in the scum collection zone 24 can enter the secondary sludge settling zone 25 through these holes. It will be appreciated that within the secondary sludge settling zone 25, sludge further settles, with incompletely recovered fine sand further settling in this area and flowing to the fine sand discharge zone 38 through the connection with the fine sand settling zone 34. Thus, the secondary sludge settling zone 25 helps improve the recovery rate of fine sand and further concentrates the excess sludge.

[0061] An overflow structure 56 is provided at the top of the overflow sludge discharge area 26, which communicates with the secondary sludge sedimentation area 25 through the overflow structure 56. The overflow sludge discharge area 26 discharges excess sludge through the sludge discharge port 27. It will be appreciated that when the sludge in the secondary sludge sedimentation area 25 reaches a certain level, the excess sludge flows through the overflow structure 56 into the overflow sludge discharge area 26 and is subsequently discharged through the sludge discharge port 27. In this way, the overflow sludge discharge area 26 ensures an appropriate sludge concentration within the system and prevents sludge overflow and pollution.

[0062] Furthermore, based on the above description of the various functional components within the device, the overall operating principle and process of this device are as follows: The entire device operates by receiving excess sludge from the sewage treatment system at the sludge inlet buffer zone 22. The fine sand is then separated from the scum and excess sludge through the cyclonic action of the cyclonic sand collection zone 23. The fine sand settles at the bottom of the cyclonic sand collection zone 23 and is discharged back into the system through the sand recovery outlet 28, while the scum is collected and discharged through the scum discharge port 29. The excess sludge then enters the sludge secondary sedimentation zone 25 through the scum collection zone 24 for further sedimentation before being discharged through the overflow structure 56 of the overflow sludge discharge zone 26. Throughout this process, fine sand is efficiently recovered, and the excess sludge discharged from the system is concentrated to the desired concentration range.

[0063] In related technologies, the Figure 1 This technical solution achieves wastewater treatment. The raw water to be purified passes through the coagulation contact tank, coagulation and sand addition tank, flocculation tank, and inclined plate sedimentation tank in the sand-added high-efficiency sedimentation tank, producing purified effluent. The conventional sand and sludge mixture at the bottom of the inclined plate sedimentation tank is pumped into the hydrocyclone via a circulation pump. Most of the fine sand enters the coagulation and sand addition tank through the lower sediment return pipe. The remaining sludge is discharged into the thickening tank through the upper pipe to the residual sludge tank. To maintain a stable concentration of sludge and fine sand in the sedimentation tank, the circulation pump must be continuously running, and the hydrocyclone operates 24 hours a day.

[0064] Therefore, the technical solutions in the above-mentioned related technologies will bring about the following technical defects.

[0065] (1) Difficulty in controlling sludge concentration: In traditional methods, a circulating pump is used to maintain a stable concentration of sludge and fine sand in the sedimentation tank. However, in actual operation, it is found that relying solely on the variable frequency control flow of the circulating pump cannot accurately control the sludge discharge volume, making it difficult to maintain the ideal sludge concentration.

[0066] (2) Fine sand loss problem: When the system is operating in a steady state, the upper sludge still contains a large amount of fine sand, resulting in a large loss of fine sand. A large amount of fine sand needs to be replenished every day, which increases the operating cost.

[0067] (3) High moisture content of residual sludge: Under traditional methods, the moisture content of residual sludge is very high, which not only increases the difficulty of subsequent treatment, but also causes a large water impact on subsequent sludge disposal and reduces the desludging efficiency.

[0068] (4) Severe equipment wear: Since a large amount of fine sand is discharged with the residual sludge, this causes serious wear on the subsequent sludge deep treatment system equipment, making the equipment easily damaged and increasing maintenance costs.

[0069] (5) Difficulty in controlling the return ratio: If the circulation pump is turned on too high, the moisture content of the residual sludge will be too high, while if it is turned on too low, the sediment separation effect will be affected. Therefore, it is difficult to find a suitable return ratio to meet the needs of fine sand recovery and sludge concentration at the same time.

[0070] In summary, in order to solve the technical defects existing in the above-mentioned related technologies, the utility model provides a system fine sand secondary recovery and sludge concentration control device 10, which can treat the emissions discharged from the sewage treatment system. On the one hand, it can realize the recycling of fine sand in the emissions, and on the other hand, it can also realize the emission control of sludge concentration, thereby solving the problems of excessive sand loss in traditional sand-added high-efficiency sedimentation tanks and excessively high moisture content of residual sludge discharge.

[0071] Furthermore, compared with the related art, the present invention has at least the following additional advantages.

[0072] (1) Energy-saving operation and low failure rate: This device uses the natural head difference of the original system as the power source and does not require additional electrical energy to drive it. Therefore, the operating cost is extremely low, energy-saving and environmentally friendly. In addition, there are no complex mechanical moving parts inside the device, and the structure is simple and reliable, which reduces the possibility of failure and reduces maintenance costs.

[0073] (2) Efficient recovery of fine sand: The unique design enables secondary recovery of fine sand, reducing the amount of fine sand required to be replenished daily from 4-6 mg / L to 2-3 mg / L, thereby reducing the consumption of fine sand and saving operating costs.

[0074] (3) Good sludge concentration effect: This device can concentrate the system sludge, reducing the moisture content of the discharged residual sludge from 99.2-99.6% to 98-99%, thereby increasing the solid content of the residual sludge and reducing the burden of subsequent sludge treatment.

[0075] (4) Improve the performance of sedimentation tank: This device can increase the concentration of sludge in the sand-added high-efficiency sedimentation tank, enhance the sedimentation tank's ability to resist the impact of suspended matter, and improve the system's processing capacity and effluent water quality.

[0076] (5) Reduce equipment wear: By effectively recovering fine sand, the content of fine sand in the discharged residual sludge is reduced, the wear of subsequent sludge treatment system equipment is reduced, and the service life of the equipment is extended.

[0077] (6) System optimization: The proportion of fine sand in the sedimentation tank was increased from 2% to 4% of the total volume of the sedimentation tank, which accelerated the sedimentation rate of flocculent sludge in the system and thus improved the effluent water quality standard.

[0078] like Figure 2 As shown, according to some embodiments of the present invention, a first regulating valve 51 with adjustable opening is provided at the recovered sand outlet 28, a second regulating valve 52 with adjustable opening is provided at the sludge discharge outlet 27, and a third regulating valve 54 with adjustable opening is provided at the sludge discharge outlet 29.

[0079] In this embodiment, a first regulating valve 51 is installed at the recovered sand outlet 28 to control the amount of fine sand recovered. By adjusting the opening of this valve, the proportion of fine sand returned to the sewage treatment system can be precisely controlled. This helps maintain a stable fine sand concentration within the sewage treatment system, reduces fine sand waste, and keeps the sewage treatment system operating at optimal conditions.

[0080] The second regulating valve 52, installed at the sludge discharge port 27, controls the amount of excess sludge discharged. Adjusting the valve opening changes the proportion of excess sludge discharged from the system, thereby controlling the sludge concentration within the system. To concentrate the excess sludge, the valve opening can be reduced to allow more sludge to flow back into the system. Conversely, to discharge more excess sludge, the valve opening can be increased.

[0081] A third regulating valve 54, installed at the scum discharge port 29, controls the amount of scum discharged. Adjusting the valve's opening adjusts the amount of scum discharged, ensuring that excessive scum accumulation in the system doesn't affect treatment efficiency. Furthermore, controlling this valve allows for the recirculation of scum that requires reprocessing.

[0082] In summary, the configuration of these three regulating valves allows the operator to flexibly adjust the material flow within the system according to actual needs, thereby effectively controlling fine sand recovery, sludge concentration, and scum discharge, ensuring optimal system operation. This design helps increase the system's level of automation, simplify operational processes, and improve the efficiency and quality of wastewater treatment.

[0083] like Figure 3 and Figure 5 As shown, according to some embodiments of the present invention, the cyclone sand collection area 23 further includes a flow guiding center cylinder 42 , which extends along the central axis of the cyclone space and the central axes of the two coincide with each other.

[0084] In the height direction of the cyclone space, the flow guiding center tube 42 is respectively arranged opposite to the mud inlet pipe 41 and the sand collecting area outlet 37 .

[0085] In this embodiment, the central guide tube 42 extends along the central axis of the vortex space, coinciding with the central axis. In the height direction of the vortex space, the central guide tube 42 is positioned corresponding to the mud inlet pipe 41 and the sand collection area outlet 37. This design helps guide and optimize the flow of fluid within the vortex space.

[0086] Its working principle is as follows: when the sand-containing residual sludge enters the cyclone space through the mud inlet pipe 41, the sludge will form a cyclone because the mud inlet pipe 41 extends along the tangential direction of the cyclone space. The presence of the guide center tube 42 helps to form a stable cyclone field, so that the fluid forms a central vortex in the cyclone space, which can enhance the separation effect between fine sand and lighter scum and residual sludge. At the sand collection area outlet 37 formed at the top of the cyclone space, the lighter scum and residual sludge will pass upward through the gap around the guide center tube 42 and eventually enter the scum collection area 24. The design of the guide center tube 42 can also help maintain the dynamic balance of the fluid in the cyclone space, prevent the cyclone from being unstable or turbulent, thereby improving the separation efficiency. It can be understood that the guide center tube 42 not only helps to form and maintain a stable cyclone, but also optimizes the separation process of fine sand and other substances, thereby improving the recovery efficiency of fine sand and the overall performance of the system.

[0087] Thus, on the one hand, the centrifugal force of the flow guide core 42 facilitates the separation of fine sand, which falls into the fine sand settling area 34. On the other hand, the scum and excess sludge are discharged through the sand collection area outlet 37. This effectively separates the fine sand from the scum and excess sludge, thereby improving the recovery rate of fine sand. Furthermore, the flow guide core 42 helps improve the stability and reliability of the system, reducing the problem of reduced separation efficiency caused by unstable fluid movement.

[0088] like Figure 3 and Figure 5 As shown, further, the cyclone sand collection area 23 also includes a guide reflector 43, which is frustum-shaped and whose central axis coincides with the central axis of the guide center tube 42, and the end of the guide reflector 43 with a smaller diameter is connected to the bottom end of the guide center tube 42.

[0089] In the height direction of the cyclone space, the guide reflector 43 is located between the mud inlet pipe 41 and the fine sand sedimentation area 34 .

[0090] In this embodiment, the deflector 43 is a truncated cone-shaped structure, with its central axis coinciding with the central axis of the deflector core 42. This ensures more regular movement of the fluid within the vortex space. The smaller end of the deflector 43 is connected to the bottom of the deflector core 42, while the larger end faces the periphery of the vortex space. This design helps guide the fluid's trajectory within the vortex space. In terms of the height of the vortex space, the deflector 43 is located between the mud inlet pipe 41 and the fine sand settling area 34, effectively controlling the flow direction of the fluid within the vortex space.

[0091] Its working principle is as follows: When the sand-containing excess sludge enters the cyclone space through the sludge inlet pipe 41, the fluid will first contact the guide reflector 43. The design of the guide reflector 43 enables the fluid to form a bidirectional cyclone. Under the action of the cyclone, the excess sludge and scum with lower density pass upward through the sand collection area outlet 37 and eventually enter the scum collection area 24. The fine sand with higher density is affected by centrifugal force and, under the action of the guide reflector 43, falls along its surface to the fine sand sedimentation area 34 below. It can be understood that the guide reflector 43, through its frustum-shaped design and position arrangement, effectively promotes the orderly movement of the fluid in the cyclone space and enhances the separation of fine sand from scum and excess sludge.

[0092] In this way, the deflector 43 helps enhance the cyclonic effect, effectively separating fine sand from scum and excess sludge. On the one hand, the design of the deflector 43 allows the fine sand to form a more concentrated sinking trajectory within the cyclonic space, helping to improve fine sand recovery efficiency. On the other hand, the deflector 43 also helps reduce the rebound of fine sand within the cyclonic space, preventing it from being discharged along with the scum and excess sludge.

[0093] like Figure 3 As shown, according to some embodiments of the present invention, a fine sand discharge area 38 is provided outside the fine sand sedimentation area 34 , and the fine sand discharge area 38 is respectively connected to the fine sand sedimentation area 34 and the sludge secondary sedimentation area 25 , and the recovered sand outlet 28 is provided on the side wall of the fine sand discharge area 38 .

[0094] In this embodiment, the fine sand discharge area 38 is located outside the fine sand settling area 34 and is connected to the fine sand settling area 34 and the sludge secondary settling area 25. The recovered sand outlet 28 is provided on the side wall of the fine sand discharge area 38 so that the fine sand can be smoothly recovered through this outlet and returned to the sand-adding high-efficiency sedimentation tank system.

[0095] Specifically, the fine sand discharge area 38 is designed to collect settled fine sand and discharge it through the recovered sand outlet 28 for reuse. The connection between the fine sand discharge area 38 and the fine sand settling area 34 allows the fine sand to flow into the fine sand discharge area 38 by gravity after settling. The connection between the secondary sludge settling area 25 and the fine sand discharge area 38 allows fine sand that failed to fully settle during the primary settling to also flow into the fine sand discharge area 38 after secondary settling.

[0096] Thus, the design of the fine sand discharge area 38 allows the fine sand to be concentrated and discharged smoothly, thereby improving the efficiency of fine sand recovery. In addition, the connection between the fine sand discharge area 38 and the two sedimentation areas ensures multiple recovery opportunities for fine sand, ensuring that as much fine sand as possible is recycled.

[0097] Furthermore, a first sand guide slope (not shown) is provided at the bottom of the system fine sand secondary recovery and sludge concentration control device 10, which gradually decreases in height along the direction from the fine sand settling area 34 to the fine sand discharge area 38. This first sand guide slope facilitates the sliding of fine sand toward the fine sand discharge area 38 under the action of gravity, thereby ensuring that the fine sand can flow smoothly into the fine sand discharge area 38 and be discharged through the recovered sand outlet 28.

[0098] A second sand guide slope (not shown) is provided at the bottom of the system's fine sand secondary recovery and sludge concentration control device 10, gradually descending in height, along the path from the secondary sludge settling zone 25 to the fine sand discharge zone 38. This second sand guide slope is also designed to ensure that fine sand that failed to fully settle during the primary settling process can smoothly slide toward the fine sand discharge zone 38 after secondary settling.

[0099] In summary, the design of fine sand discharge area 38 and the use of a sand guide slope ensure that fine sand is effectively collected and discharged through the recovered sand outlet 28, thereby improving fine sand recovery efficiency. Furthermore, the design of the sand guide slope allows fine sand to naturally slide toward the fine sand discharge area 38 under the action of gravity, reducing the possibility of fine sand being retained in the system and minimizing fine sand loss.

[0100] For example Figures 2 to 5As shown, the sand-containing excess sludge passes through the sand collection zone inlet 31 and enters the sand collection zone housing. Guided by the mud inlet pipe 41, the sand-containing excess sludge swirls in the water inlet diversion zone 32. The diversion center tube 42 and the diversion reflector 43 work together to form a bidirectional vortex. The excess sludge, with a density of 1.06 kg / m³, passes upward through the cyclonic separation layer 35 and the sludge stabilization layer 36, ultimately entering the scum collection zone 24 through the sand collection zone outlet 37. Fine sand, with a true density of approximately 2650 kg / m³, is centrifugally driven through the cyclonic reflector 33 and along the diversion reflector 43 into the fine sand settling zone 34. The bottom and periphery of the fine sand settling zone 34 are connected to the outer fine sand discharge zone 38 via a bottom connecting ring 44. Fine sand flows along the internal slope into the fine sand discharge zone 38 and is ultimately discharged back into the coagulation and sand adding tank 3 through the recovered sand outlet 28, achieving secondary recovery of fine sand.

[0101] The bottoms of the sludge secondary sedimentation area 25, the fine sand sedimentation area 34 and the fine sand discharge area 38 of this device are interconnected. The fine sand deposited at the bottom can eventually generate discharge power under the action of the vortex in the fine sand sedimentation area 34, and finally be discharged back to the coagulation and sand adding tank 3 through the recovered sand outlet 28, thereby achieving the purpose of recovering the fine sand again.

[0102] like Figure 2 As shown, according to some embodiments of the present invention, a sludge through hole 55 is provided at the bottom of the sludge collecting area 24. It can be understood that this design is to allow the sludge in the sludge collecting area 24 to enter the sludge secondary sedimentation area 25 through this hole.

[0103] In the actual treatment process, the remaining sludge and scum after separation in the cyclone sand collection area 23 are transported to the scum collection area 24. The sludge at the bottom of the scum collection area 24 enters the sludge secondary sedimentation area 25 through holes 55 for further sedimentation. This design ensures that the sludge remains in the sludge collection area 24 for a sufficient period of time to remove most of the sludge before entering the sludge secondary sedimentation area 25 for more refined treatment.

[0104] Thus, the design of the sludge passage holes 55 allows the sludge to flow naturally into the sludge secondary sedimentation zone 25 under the action of gravity, reducing energy consumption. Furthermore, the separation of the sludge collection zone 24 and the sludge secondary sedimentation zone 25 allows the sludge to be effectively removed in the sludge collection zone 24 while the sludge can be more thoroughly processed in the secondary sedimentation zone, thereby improving the sludge concentration effect.

[0105] like Figure 2 As shown, according to some embodiments of the present invention, the sludge buffer area 22 is connected to the sludge secondary sedimentation area 25 through an overflow hole 57 provided at the top thereof. It can be understood that the overflow hole 57 is designed to handle the situation where the sludge buffer area 22 exceeds the capacity.

[0106] The overflow hole 57 works as follows: when the amount of sludge in the sludge buffer area 22 reaches a certain level, the excess sludge will flow into the sludge secondary sedimentation area 25 through the overflow hole 57. This is done to prevent the sludge buffer area 22 from being overfilled and causing sludge overflow, while ensuring that the system can operate continuously and stably.

[0107] In this way, the design of the overflow hole 57 ensures that the mud buffer area 22 will not overflow due to excessive sludge, thereby maintaining the normal operation of the system. Further, the excess sludge entering the sludge secondary sedimentation area 25 through the overflow hole 57 can continue to be processed, avoiding the waste of sludge.

[0108] Furthermore, the rational hole design in the above-mentioned device structure allows for smooth transition of sludge between different treatment stages, reducing sludge stagnation time within the system and improving treatment efficiency. This design reduces the need for manual intervention, making the system more automated, simplifying the operation process, and reducing maintenance costs.

[0109] like Figure 2 As shown, according to some embodiments of the present invention, the overflow structure 56 is an overflow weir disposed on the top of the overflow mud discharge area 26 , and the overflow weir is sawtooth-shaped and extends along the top wall of the overflow mud discharge area 26 .

[0110] It should be noted that the overflow weir in this embodiment is a structure disposed at the top of the overflow sludge discharge area 26, arranged in a zigzag pattern and extending along the top wall of the overflow sludge discharge area 26. The zigzag design provides the overflow weir with multiple staggered edges of varying heights, thereby controlling the flow of sludge through the overflow weir.

[0111] Specifically, its working principle is as follows: when the amount of sludge in the secondary sludge sedimentation area 25 exceeds a set height, the excess sludge overflows through the overflow weir and flows into the overflow sludge discharge area 26. The serrated overflow weir design allows the sludge to pass through multiple small drops when overflowing, which helps to further separate fine sand and other impurities in the sludge. The fine sand may settle again when flowing over the serrated edges, while the lighter sludge continues to move forward with the water flow.

[0112] The serrated overflow weir design distributes overflowing sludge more evenly, reducing the risk of local overload and ensuring system stability. Furthermore, the multiple small drops along the serrated edge further improve fine sand recovery efficiency and reduce the likelihood of fine sand being discharged with the sludge. Furthermore, the serrated design increases the surface area of the water flow, helping to improve sludge separation and reduce the fine sand content in discharged sludge.

[0113] It should be pointed out that the overflow structure 56 may also adopt other structures, and the present invention does not make any special limitation here, as long as the overflow structure 56 can achieve the function of overflow communication.

[0114] The following describes the control method, control device and system fine sand secondary recovery and sludge concentration control device 10 proposed in the present invention with reference to the accompanying drawings. Before describing the embodiment of the present invention in detail, the entire application scenario is first described. The control method, control device, electronic device and computer-readable storage medium of the system fine sand secondary recovery and sludge concentration control device 10 of the embodiment of the present invention can be applied to the system fine sand secondary recovery and sludge concentration control device 10 locally, and can also be applied to cloud platforms in the Internet field, or other types of cloud platforms in the Internet field, or can also be applied to third-party devices. Among them, third-party devices may include many different types such as mobile phones, tablet computers, notebooks, car computers and other smart terminals.

[0115] The following description only takes the control method applicable to the system fine sand secondary recovery and sludge concentration control device 10 as an example. It should be understood that the control method of the embodiment of the present utility model can also be applied to cloud platforms and third-party equipment.

[0116] like Figure 6 As shown, the control method of the system fine sand secondary recovery and sludge concentration control device 10 according to the embodiment of the second aspect of the utility model includes:

[0117] Step S1, obtaining the target concentration range of sludge discharged from the system;

[0118] Step S2: controlling and adjusting the openings of the first regulating valve 51 and the second regulating valve 52 according to the target concentration range.

[0119] The control method for the fine sand secondary recovery and sludge concentration control device 10 according to an embodiment of the present invention operates as follows: First, the state of the residual sludge discharged from the system is monitored in real time using a flow meter and a mud level monitor, and a target concentration range is set. Based on the target concentration range, the openings of the first regulating valve 51 and the second regulating valve 52 are adjusted using an automatic control system algorithm.

[0120] Specifically, if the concentration of sludge in the system needs to be increased, the opening of the second regulating valve 52 can be appropriately reduced while the opening of the first regulating valve 51 can be increased to allow more sludge to flow back. If the concentration of sludge in the system needs to be reduced, the opening of the second regulating valve 52 can be appropriately increased while the opening of the first regulating valve 51 can be reduced to allow more sludge to be discharged.

[0121] Furthermore, the system will compare the actual concentration of discharged sludge with the target concentration range, and automatically adjust the opening of the two regulating valves according to the deviation until the set target concentration range is reached.

[0122] In this way, through the above steps, the system fine sand secondary recovery and intelligent control of the sludge concentration control device 10 can be achieved, ensuring that the discharged residual sludge reaches the ideal concentration range, which not only improves the operating efficiency of the system but also reduces the cost of subsequent treatment.

[0123] In practical applications, the device of the present invention controls the sludge concentration of the system by controlling the first regulating valve 51 and the second regulating valve 52. Some specific embodiments of the control method of the present invention are given below.

[0124] 1) When the first regulating valve 51 is fully opened, the device returns all incoming sludge regardless of the opening degree of the second regulating valve 52. At this time, the device of the present invention does not discharge excess sludge.

[0125] 2) When the first regulating valve 51 is fully closed, the second regulating valve 52 is programmed to be fully opened. At this point, the system is merely short-circuiting, and all excess sludge is discharged, without recovering fine sand. However, if the third electric valve is opened at this point, the system can recover and reprocess the scum.

[0126] 3) The second regulating valve 52 is fully open or moderately closed. The opening of the first regulating valve 51 can be adjusted to control the proportion of sludge returned to the system. A wider opening of the first regulating valve 51 increases the amount of sludge returned and reduces the amount of excess sludge discharged. This concentrates the sludge in the system, lowering the moisture content of the discharged chemical excess sludge and improving the excess sludge concentration.

[0127] 4) The second regulating valve 52 is fully opened or moderately closed. If the opening of the first regulating valve 51 is smaller, the sludge return volume will be smaller and the residual sludge discharge volume will be larger. At this time, the sludge concentration in the system will decrease, and the moisture content of the discharged chemical residual sludge will increase, thereby reducing the residual sludge concentration effect.

[0128] 5) In addition, Example 3) and Example 4) can be further combined with the flow meter and the mud level monitor of the inclined plate sedimentation tank 5, and the opening size of the first regulating valve 51 and the second regulating valve 52 can be remotely controlled through the automatic control system algorithm, so that the chemical residual sludge discharged from the system can be concentrated to the required concentration range to meet the target requirements.

[0129] like Figure 7As shown, the utility model also protects a sewage treatment system, which includes the system fine sand secondary recovery and sludge concentration control device 10 as described in the embodiment of the first aspect of the utility model, and also includes a coagulation contact tank 2, a coagulation sand adding tank 3, a flocculation tank 4, and an inclined plate sedimentation tank 5 connected in sequence.

[0130] Among them, the inclined plate sedimentation tank 5 is connected to the hydrocyclone 7 through the purified water outlet 6, the sediment return pipe 8 of the hydrocyclone 7 is connected to the coagulation and sand adding tank 3, and the residual sludge discharge pipe 9 of the hydrocyclone 7 is connected to the mud inlet 21 of the system fine sand secondary recovery and sludge concentration control device 10, and the recovered sand outlet 28 of the system fine sand secondary recovery and sludge concentration control device 10 is also connected to the coagulation and sand adding tank 3.

[0131] According to the sewage treatment system of the embodiment of the present utility model, its specific working process is as follows: the raw water 1 is sequentially treated by the coagulation contact tank 2, the coagulation sand adding tank 3 and the flocculation tank 4, and coagulants and sand media are added to promote the coagulation and flocculation of pollutants. The pretreated sewage enters the inclined plate sedimentation tank 5, where the mud and water are separated by gravity, and the purified water is discharged from the system. The separated sludge enters the hydrocyclone 7, and most of the fine sand returns to the coagulation sand adding tank 3 through the sedimentation return pipe 8, and the remaining sludge enters the system fine sand secondary recovery and sludge concentration control device 10. In the system fine sand secondary recovery and sludge concentration control device 10, the remaining sludge undergoes cyclone separation, and the fine sand returns to the coagulation sand adding tank 3 through the recovered sand outlet 28, and the concentrated remaining sludge is discharged from the system through the sludge discharge port 27.

[0132] In summary, through this series of treatment steps, efficient recovery of fine sand and concentration of residual sludge are achieved, thereby improving the overall efficiency and operation effect of the sewage treatment system.

[0133] Figure 8 An example of a physical structure diagram of an electronic device is shown below. Figure 8 As shown, the electronic device may include: a processor 810, a communications interface 820, a memory 830, and a communications bus 840. The processor 810, the communications interface 820, and the memory 830 communicate with each other via the communications bus 840. The processor 810 may invoke logic instructions in the memory 830 to execute a control method for the system fine sand secondary recovery and sludge concentration control device 10, including: obtaining a target concentration range for the system discharged sludge; and controlling and adjusting the openings of the first regulating valve 51 and the second regulating valve 52 according to the target concentration range.

[0134] In addition, the logic instructions in the above-mentioned memory 830 can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when it is sold or used as an independent product. Based on this understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art or the part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the various embodiments of the present invention. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0135] On the other hand, the utility model also provides a computer program product, which includes a computer program. The computer program can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can execute the control method of the system fine sand secondary recovery and sludge concentration control device 10 provided by the above methods, including: obtaining the target concentration range of the system discharged sludge; according to the target concentration range, controlling and adjusting the opening of the first regulating valve 51 and the second regulating valve 52.

[0136] On the other hand, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, it is implemented to execute the control method of the system fine sand secondary recovery and sludge concentration control device 10 provided by the above-mentioned methods, including: obtaining the target concentration range of the system discharged sludge; according to the target concentration range, controlling and adjusting the opening of the first regulating valve 51 and the second regulating valve 52.

[0137] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units. That is, they may be located in one place or distributed across multiple network units. Some or all of the modules may be selected based on actual needs to achieve the objectives of the present embodiment. Persons of ordinary skill in the art will be able to understand and implement the present invention without inventive effort.

[0138] Through the description of the above embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus the necessary general hardware platform, or of course, by hardware. Based on this understanding, the essence of the above technical solution or the part that contributes to the existing technology can be embodied in the form of a software product. The computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a magnetic disk, an optical disk, etc., and includes a number of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods of each embodiment or certain parts of the embodiment.

[0139] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A system fine sand secondary recovery and sludge concentration control device, characterized in that: include: a mud inlet buffer area having a mud inlet connected to a discharge outlet of the sewage treatment system for receiving discharge from the system; A cyclone sand collection area is connected to the sludge inlet buffer area through a sludge inlet pipe, and a cylindrical cyclone space is formed inside the cyclone sand collection area. The sludge inlet pipe extends in a tangential direction of the cyclone space so that the discharge forms a cyclone. A fine sand sedimentation area is formed at the bottom of the cyclone space, and the fine sand sedimentation area is connected to the outside through a recovered sand outlet. A sand collection area outlet is formed at the top of the cyclone space. Under the action of the cyclone, the fine sand in the discharge falls into the fine sand sedimentation area, and the scum and sludge in the discharge are discharged through the sand collection area outlet. A scum collection area is connected to the sand collection area outlet of the cyclone sand collection area, and the scum collection area is connected to the outside through a scum discharge port; a sludge secondary sedimentation zone, connected to the sludge collection zone through a sludge through hole, and the sludge in the sludge collection zone enters the sludge secondary sedimentation zone through the sludge through hole; The overflow mud discharge area is provided with an overflow structure on the top of the overflow mud discharge area. The sludge secondary sedimentation area is connected with the overflow mud discharge area through the overflow structure, and the overflow mud discharge area is connected to the outside through the sludge discharge port.

2. The system fine sand secondary recovery and sludge concentration control device according to claim 1 is characterized in that: A first regulating valve with adjustable opening is provided at the recovered sand outlet, and a second regulating valve with adjustable opening is provided at the sludge discharge outlet.

3. The system fine sand secondary recovery and sludge concentration control device according to claim 2 is characterized in that: The cyclone sand collection area further includes a flow guiding center cylinder, which extends along the central axis of the cyclone space and the central axes of the two coincide with each other; In the height direction of the vortex space, the flow guide central cylinder is respectively arranged opposite to the mud inlet pipe and the sand collection area outlet.

4. The system fine sand secondary recovery and sludge concentration control device according to claim 3 is characterized in that: The cyclone sand collection area further includes a guide reflector plate, which is truncated cone-shaped and has a central axis that coincides with the central axis of the guide central tube. The end of the guide reflector plate with a smaller diameter is connected to the bottom end of the guide central tube. In the height direction of the cyclone space, the guide reflector is located between the mud inlet pipe and the fine sand precipitation area.

5. The system fine sand secondary recovery and sludge concentration control device according to any one of claims 2 to 4, characterized in that: A fine sand discharge area is provided outside the fine sand sedimentation area. The fine sand discharge area is connected to the fine sand sedimentation area and the sludge secondary sedimentation area respectively. The recovered sand outlet is provided on the side wall of the fine sand discharge area.

6. The system fine sand secondary recovery and sludge concentration control device according to claim 5 is characterized in that: In the direction from the fine sand sedimentation area to the fine sand discharge area, a first sand guide slope with a gradually decreasing height is provided at the bottom of the fine sand secondary recovery and sludge concentration control device of the system; And / or, in the direction from the sludge secondary sedimentation zone to the fine sand discharge zone, a second sand guide slope with a gradually decreasing height is provided at the bottom of the system fine sand secondary recovery and sludge concentration control device.

7. The system fine sand secondary recovery and sludge concentration control device according to any one of claims 2 to 4, characterized in that: The sludge passing hole is provided at the bottom of the scum collecting area.

8. The system fine sand secondary recovery and sludge concentration control device according to any one of claims 2 to 4, characterized in that: The sludge inlet buffer area is connected to the sludge secondary sedimentation area through an overflow hole arranged on the top of the sludge inlet buffer area.

9. The system fine sand secondary recovery and sludge concentration control device according to any one of claims 2 to 4, characterized in that: The overflow structure is an overflow weir arranged at the top of the overflow mud discharge area. The overflow weir is sawtooth-shaped and extends along the top wall of the overflow mud discharge area.

10. A sewage treatment system, characterized in that: include: The system fine sand secondary recovery and sludge concentration control device according to any one of claims 1 to 9; The coagulation contact tank, coagulation sand adding tank, flocculation tank and inclined plate sedimentation tank are connected in sequence. The inclined plate sedimentation tank is connected to the hydrocyclone through the purified water outlet. The sediment return pipe of the hydrocyclone is connected to the coagulation sand adding tank, and the residual sludge discharge pipe of the hydrocyclone is connected to the mud inlet of the system fine sand secondary recovery and sludge concentration control device, and the recovered sand outlet of the system fine sand secondary recovery and sludge concentration control device is also connected to the coagulation sand adding tank.

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