A heavy sludge screening device and method for a sewage treatment system

Abstract

The application discloses a heavy sludge screening device and method for a sewage treatment system. The device comprises a mixed sludge inlet section, a sludge screening section, a light sludge outlet section, a heavy sludge outlet section and a support structure; the mixed sludge inlet section comprises a sludge inlet pipeline connecting flange interface, a sludge inlet pressure sensor, a sludge inlet main pipe, a sludge inlet sampling port, a sludge inlet branch pipe manual valve and a sludge inlet branch pipe pressure gauge; the sludge screening section comprises a cyclone separator which is provided with a tangential sludge inlet, a top light sludge discharge port and a bottom heavy sludge discharge port; the light sludge outlet section comprises a light sludge discharge port branch pipe, a light sludge discharge port main pipe, a light sludge sampling port and a light sludge discharge flange interface; and the heavy sludge outlet section comprises a heavy sludge receiving flange, a heavy sludge discharge port main pipe, a heavy sludge sampling port and a heavy sludge discharge flange interface. The application can effectively separate light sludge and heavy sludge from backflow sludge or residual sludge.

Description

Technical Field

[0001] This invention belongs to the field of wastewater biological treatment technology, specifically relating to a screening device and method for separating and extracting heavy sludge. Background Technology

[0002] Sludge floating and sludge bulking have different causes and manifestations. Sludge floating can occur in biological treatment tanks and secondary settling tanks, but it is more common in secondary settling tanks. This may be due to anaerobic decomposition caused by sludge hypoxia, leading to the disintegration of granular sludge and the release of large amounts of gas, causing lighter, flocculent sludge to float to the surface of the secondary settling tank. Alternatively, it may be caused by prolonged residence time of wastewater in the secondary settling tank, resulting in hypoxia, which causes denitrifying bacteria to produce ammonia and nitrogen gas during denitrification, leading to sludge adsorption and floating. Sludge bulking is mostly caused by the overgrowth of filamentous bacteria, followed by non-filamentous bacteria bulking, often due to excessively high dissolved organic matter content or the presence of many toxic substances in the influent. These abnormal operating conditions can lead to excessive suspended solids (SS) in the effluent, affecting effluent quality, and in severe cases, even causing seasonal disruptions to the entire process system. Superficially, similar problems will lead to a decline in sludge settling performance (SVI).

[0003] Recent research indicates that adjusting the balance between granular and flocculent sludge in biological treatment tanks using externally driven hydraulic selectors can achieve higher settling rates and offer additional benefits. Separating granular sludge using selectors not only suppresses seasonal sludge bulking or occasional sludge floating, but also improves the nitrogen and phosphorus removal efficiency of the biological treatment system, reduces COD waste, lowers effluent SS, and stabilizes SVI to effectively prevent sludge bulking, thus reducing wastewater treatment plant operating costs. The heavy sludge mentioned here is not granular sludge, but specifically refers to relatively dense sludge separated by density difference. Its particle size is slightly smaller than traditional granular sludge, and upon returning to the biological reactor, it serves as a core for microbial attachment and growth, providing a basis for the formation of larger sludge particles. The concept of light sludge corresponds to this. There are currently various hydrocyclones available in my country and they are widely used. However, the existing sludge hydrocyclones and their usage methods have shortcomings when applied to the separation of heavy sludge and light sludge.

[0004] Chinese patent ZL202011326485.5 discloses a hydrocyclone separator for sludge separation and its usage method, comprising an upper cylindrical section, a lower conical section, and a top overflow section. The cone section contains densely distributed protruding hemispherical hard plastic or metal particles. Its inlet is rectangular. The overflow port of the top overflow section is inserted into the cylindrical section at approximately 0.3 to 0.55 times the diameter of the hydrocyclone. Other specifications define the various dimensions of the hydrocyclone itself. This invention is characterized by its application in separating sludge mixtures containing powdered carriers. Due to its unique shape and structural design, the hemispherical hard plastic or metal particles inside the hydrocyclone cause increased water loss during operation. The higher particle density at the top may cause the granular heavy sludge to be broken up, leading to reduced separation efficiency. Therefore, this design is only suitable for separating mixed sludge containing powdered carriers and is not suitable for separating heavy and light sludge. In addition, it requires welding or bonding 200,000 to 400,000 particles per square meter, and if the particles fall off, it may cause blockage of the hydrocyclone's underflow port. Most importantly, after the flow rate and pressure at the hydrocyclone's inlet are set, this invention has difficulty in flexibly controlling the flow ratio between the overflow port and the underflow port, which directly affects the hydrocyclone separation effect. Summary of the Invention

[0005] To address the aforementioned deficiencies, this invention provides a sludge screening device and method for biological sludge separation. This device utilizes a variable frequency sludge conveying pump to pressurize and transport mixed sludge, thereby separating light and heavy sludge using cyclone separation. After continuous use for a certain period, this device can reduce the SVI (sulfuric acid viscosity) in the biological treatment tank and optimize nitrogen and phosphorus removal.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A heavy sludge screening device for a wastewater treatment system, used for separating heavy sludge and light sludge, includes a mixed sludge inlet section, a sludge screening section, a light sludge outlet section, a heavy sludge outlet section, and a supporting structure; the mixed sludge inlet section includes an inlet pipe flange interface, an inlet pressure sensor, an inlet main pipe, an inlet sampling port, an inlet branch pipe manual valve, and an inlet branch pipe pressure gauge; the sludge screening section includes a hydrocyclone separator, which is provided with a tangential sludge inlet, a top light sludge discharge port, and a bottom heavy sludge discharge port; the light sludge outlet section includes a light sludge discharge port branch pipe, a light sludge discharge port main pipe, a light sludge sampling port, and a light sludge discharge flange interface; the heavy sludge outlet section includes a heavy sludge receiving flange, a heavy sludge discharge port main pipe, a heavy sludge sampling port, and a heavy sludge discharge flange interface; the supporting structure includes an equipment skid; wherein:

[0008] The inlet sludge pipe is connected to the flange interface of the inlet sludge inlet pressure sensor; the inlet sludge inlet pressure sensor is connected to the main inlet sludge inlet pipe; the main inlet sludge inlet pipe is connected to the manual valve of the inlet sludge branch pipe; the manual valve of the inlet sludge branch pipe is connected to the pressure gauge of the inlet sludge branch pipe through a pipe; the pressure gauge of the inlet sludge branch pipe is connected to the tangential inlet sludge inlet; the bottom heavy sludge discharge port and the heavy sludge receiving flange are vertically coaxial; the heavy sludge receiving flange is connected to the main heavy sludge discharge port pipe; the top light sludge discharge port is connected to the branch pipe of the light sludge discharge port; the light sludge discharge... The outlet branch pipe is freely placed in the inlet of the main light sludge discharge pipe; the main light sludge discharge pipe is connected to the heavy sludge discharge flange interface; the sludge inlet sampling port is installed on the flange opposite to the sludge inlet pipe connection flange interface; the heavy sludge sampling port is installed on the flange opposite to the heavy sludge discharge flange interface; the light sludge sampling port is installed on the lower side of the light sludge discharge flange interface; the main sludge inlet pipe, the main heavy sludge discharge pipe, the main light sludge discharge pipe, and the hydrocyclone separator are fixed on the equipment skid.

[0009] Furthermore, the main body of the cyclone separator is assembled from an upper cylindrical section and a lower conical section; the bottom of the cyclone separator is equipped with an underflow inlet drive mechanism and an underflow inlet electric actuator, the underflow inlet drive mechanism being connected to the underflow inlet electric actuator, and the underflow inlet drive mechanism being connected to the bottom heavy sludge discharge port; the inner diameter of the bottom opening of the heavy sludge discharge port can be adjusted by the underflow inlet drive mechanism and the underflow inlet electric actuator, and the underflow inlet diameter of the heavy sludge discharge port can be adjusted within the range of 0.1 to 0.5 times the diameter of the cylindrical section.

[0010] Furthermore, the hydrocyclone separators are available in two sizes to accommodate different sludge screening volumes required for various scenarios. Each sludge screening unit can be paired with 3 / 4 / 5 sets, or other quantities, of large or small hydrocyclones. The small hydrocyclone separator has a cylinder diameter of 80mm~100mm and a processing capacity of 0-10 m³ / h. 3 / h; the diameter of the cylindrical section of the large-scale hydrocyclone separator is 110mm~130mm, and the water treatment capacity is 10~30 m³ / h. 3 / h; Both models of the cyclone separator have the following characteristics: the cone angle of the cone section is 6°~9°, the cone ratio is in the range of 0.2~0.8, the depth of the top light sludge discharge port inserted into the cylinder section is 0.6~0.8 times the diameter of the cylinder section, the diameter of the part of the top light sludge discharge port inserted into the cylinder section is 0.2~0.4 times the diameter of the cylinder section, and the tangential sludge inlet is circular with a diameter of 0.6~0.8 times the diameter of the cylinder section.

[0011] Furthermore, the dimensions of the flange interface of the mud inlet pipe and the main mud inlet pipe need to be adjusted according to the total water flow rate to ensure that the liquid flow velocity in the pipe is within the range of 0.5~0.9 m / s.

[0012] Furthermore, the manual valve of the mud inlet branch pipe is installed at the front end of the mud inlet branch pipe, and a pipe section distance of not less than 5 times the diameter of the mud inlet branch pipe is left between it and the installation position of the pressure gauge of the mud inlet branch pipe.

[0013] Furthermore, the branch pipe of the light sludge discharge outlet is a light flexible hose, one end of which is connected to the top light sludge discharge outlet using a pipe clamp or clamp, and the other end is freely placed in the inlet of the main pipe of the light sludge discharge outlet, so that the light sludge can flow freely under atmospheric pressure.

[0014] Furthermore, the heavy sludge receiving flange and the heavy sludge discharge port at the bottom of the cyclone separator are installed along the same vertical axis but do not contact each other, but are spaced about 100-200 mm apart, so that the heavy sludge can flow freely under atmospheric pressure; the heavy sludge receiving flange serves as the heavy sludge receiving interface, and its interface diameter is 2-5 times the diameter of the bottom heavy sludge discharge port.

[0015] Furthermore, the equipment skid includes a wind baffle plate, which is installed on the outside of the heavy sludge receiving interface, i.e., the heavy sludge receiving flange.

[0016] The present invention also provides a method for screening heavy sludge using the above-mentioned heavy sludge screening device, comprising the following steps:

[0017] 1) Mixed sludge inlet section: The mixed sludge enters the heavy sludge screening device from the flange interface of the sludge inlet pipe. After passing the sludge inlet pressure sensor, it enters the sludge inlet main pipe. Then, the mixed sludge is evenly distributed to each sludge inlet branch pipe through the manual valve of the sludge inlet branch pipe. The pressure of each branch pipe is adjusted to be roughly balanced by the sludge inlet branch pipe pressure gauge. Finally, it enters the sludge screening section through the tangential sludge inlet.

[0018] 2) Sludge screening section: The mixed sludge enters the hydrocyclone separator through the tangential sludge inlet. The lighter part flows to the top light sludge discharge port and then enters the light sludge outlet section, while the heavier part flows to the bottom heavy sludge discharge port and then enters the heavy sludge outlet section.

[0019] 3) Light sludge outlet section: Light sludge enters the light sludge outlet branch pipe through the top light sludge outlet. The light sludge flows freely in the light sludge outlet main pipe under atmospheric pressure. Then, the light sludge flows through the light sludge outlet main pipe to the light sludge outlet flange interface and is discharged.

[0020] 4) Heavy sludge outlet section: Heavy sludge flows into the corresponding heavy sludge receiving flange through the bottom heavy sludge discharge port under gravity, and then into the heavy sludge discharge port main pipe, and finally is discharged through the heavy sludge discharge flange interface.

[0021] Furthermore, in the above method, a variable frequency sludge transfer pump is used to pump the return sludge or excess sludge discharged from the secondary sedimentation tank at a pressure of 0.15 MPa to 0.35 MPa. Depending on the application scenario, each sludge screen is equipped with 3 / 4 / 5 sets of large or small hydrocyclones at a pressure of 3 m. 3 / h~200 m 3 The flow rate is fed into the sludge screening device at a rate of / h. After being processed by the heavy sludge screening device, the heavy sludge (the denser and more compact activated sludge portion) obtained by the heavy sludge screening device is returned to the biological treatment tank for retention. At the same time, the light sludge (the lighter and looser sludge portion, such as filamentous bacteria) is discharged to the sludge treatment device to be discharged from the activated sludge system.

[0022] In the above method, heavy sludge has a higher density and better settling performance, and it helps to form granular sludge after being returned to the biological treatment tank. After screening, the heavy sludge has an increased specific gravity and settling velocity, which can effectively improve the sludge settling performance. At the same time, the heavy sludge contains polyphosphate-accumulating bacteria (PAOs), ammonia-oxidizing bacteria (AOBs), nitrite-oxidizing bacteria (NOBs), denitrifying heterotrophic bacteria, and even anaerobic ammonia-oxidizing bacteria (Anammox), which can enhance the biological nitrogen and phosphorus removal capacity. During operation, water samples can be taken periodically from the sludge inlet, heavy sludge sampling inlet, light sludge sampling inlet, and biological treatment tank outlet to test parameters such as dissolved oxygen, sludge TSS, sludge density, SVI, BOD, COD, NH3-N, NOx-N, TN, and TP to confirm the actual impact of the sludge screening system.

[0023] The beneficial effects of this invention are as follows:

[0024] 1. Under the premise that the flow rate of the variable frequency sludge conveying pump can be freely adjusted to a certain extent, the size of the bottom discharge port of the hydrocyclone can be adjusted by the actuator and the transmission mechanism to achieve a constant flow ratio between the top overflow and the bottom outflow.

[0025] 2. This invention can effectively separate light sludge and heavy sludge from returned sludge or excess sludge, and continuously return the heavy sludge to the biological system, which can reduce sludge bulking and sludge floating, and enhance the denitrification and phosphorus removal effect.

[0026] 3. This invention can flexibly adapt to various influent flow rates. By setting up multiple devices, large-flow sludge screening can be achieved without pressure loss. More specifically, the device skid can accommodate various models of hydrocyclones. The variable frequency sludge conveying pump can be adjusted as needed, or the manual valve of the sludge inlet branch pipe can be adjusted to allow single or multiple hydrocyclones to be on standby or in operation, thus meeting the needs of different working conditions.

[0027] 4. This invention can improve the sludge operation in the biological system after long-term operation without adding new sewage treatment structures or main process equipment. It mainly improves the sludge operation by continuously discharging light flocculent sludge out of the system while transporting heavy sludge back into the biological system, thereby increasing the proportion of sludge with high specific gravity and good settling performance in the system, thus improving the sludge settling rate and reducing sludge expansion or floating.

[0028] 5. If an appropriate flow control sensor and sludge conveying pump are added to achieve linkage, and other sensors and PLC are added at the same time, the present invention can achieve fully automated operation. It can even be equipped with some automatic sampling and detection equipment to periodically sample and save data to form charts and upload them to the user's port, which has good scalability and operability. Attached Figure Description

[0029] Figure 1 This is a front view of the heavy sludge screening device of the present invention.

[0030] Figure 2 This is a rear view schematic diagram of the heavy sludge screening device of the present invention.

[0031] Figure 3 This is a schematic diagram of the left-hand structure of the heavy sludge screening device of the present invention.

[0032] Figure 4 This is a right-side structural schematic diagram of the heavy sludge screening device of the present invention.

[0033] Figure 5 This is a top view of the heavy sludge screening device of the present invention.

[0034] Figure 6 This is a three-dimensional structural schematic diagram of the heavy sludge screening device of the present invention.

[0035] Figure 7 This is a schematic diagram of the heavy sludge screening device of the present invention, which is equipped with three sets of hydrocyclones.

[0036] Figure 8 This is a schematic diagram of the heavy sludge screening device of the present invention, which is equipped with 5 sets of hydrocyclones.

[0037] Figure 9 This is a schematic diagram of the hydrocyclone separator structure of the heavy sludge screening device of the present invention.

[0038] Figure 10 This is a schematic diagram of the bottom connection method of the hydrocyclone in the heavy sludge screening device of the present invention.

[0039] Figure 11 This is a schematic diagram of one embodiment of the heavy sludge screening device of the present invention.

[0040] Figure 12 This is a comparison chart of SVI30 changes during a one-year experiment of the heavy sludge screening device of the present invention.

[0041] Figure 13 This is a particle size distribution diagram of the heavy sludge screening device of the present invention.

[0042] Numbered in the diagram: 1. Sludge inlet pipe flange connection; 2. Heavy sludge discharge flange connection; 3. Light sludge discharge flange connection; 4. Equipment skid; 5. Manual valve for sludge inlet branch pipe; 6. Hydrocyclone separator; 7. Top light sludge discharge port; 8. Main light sludge discharge port; 9. Heavy sludge receiving flange; 10. Sludge inlet pressure sensor; 11. Pressure gauge for sludge inlet branch pipe; 12. Sludge inlet sampling port; 13. Heavy sludge sampling port; 14. Light sludge sampling port; 15. Light sludge discharge port branch pipe; 16. Main sludge inlet pipe; tangential inlet... 17. Sludge outlet, 18. Bottom heavy sludge discharge outlet, 19. Main heavy sludge discharge outlet, 20. Cylindrical section, 21. Conical section, 22. Underflow outlet transmission mechanism, 23. Underflow outlet electric actuator, 24. Variable frequency sludge transfer pump, 25. Biological tank, 26. Secondary sedimentation tank, 27. Sludge tank, 28. Sludge treatment device, 29. First pipe, 30. Second pipe, 31. Third pipe, 32. Fourth pipe, 33. Fifth pipe, 34. Mixed sludge flow sensor, 35. Heavy sludge flow sensor, 36. Baffle plate. Detailed Implementation

[0043] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments and accompanying drawings.

[0044] Example 1:

[0045] like Figure 1-10 The diagram shows a heavy sludge screening device for a wastewater treatment system, used for separating heavy and light sludge. It includes a mixed sludge inlet section, a sludge screening section, a light sludge outlet section, a heavy sludge outlet section, and a support structure. The mixed sludge inlet section includes an inlet pipe flange interface 1, an inlet pressure sensor 10, an inlet main pipe 16, an inlet sampling port 12, an inlet branch pipe manual valve 5, and an inlet branch pipe pressure gauge 11. The sludge screening section includes a hydrocyclone separator 6, which comprises a tangential inlet 17, a top light sludge discharge port 7, a bottom heavy sludge discharge port 18, a cylindrical section 20, a conical section 21, a bottom flow port transmission mechanism 22, and a bottom flow port electric actuator 23. The light sludge outlet section includes a light sludge discharge port branch pipe 15, a light sludge discharge port main pipe 8, a light sludge sampling port 14, and a light sludge discharge flange interface 3. The heavy sludge outlet section includes a heavy sludge receiving flange 9, a heavy sludge discharge main pipe 19, a heavy sludge sampling port 13, and a heavy sludge discharge flange interface 2; the supporting structure includes an equipment skid 4, which includes a wind baffle 36.

[0046] The mixed sludge enters through flange interface 1 of the inlet pipe; flange interface 1 of the inlet pipe is connected to inlet pressure sensor 10; inlet pressure sensor 10 is connected to inlet main pipe 16; inlet main pipe 16 is connected to inlet branch pipe manual valve 5; inlet branch pipe manual valve 5 is connected to inlet branch pipe pressure gauge 11 via a pipe. Inlet branch pipe pressure gauge 11 is connected to tangential inlet 17, entering the hydrocyclone separator 6. The hydrocyclone separator 6... Figure 9 As shown, the upper part has a top light sludge discharge port 7; the side of the hydrocyclone 6 has a tangential sludge inlet 17; the hydrocyclone 6 body is assembled from an upper cylindrical section 20 and a lower conical section 21; the bottom of the hydrocyclone 6 is connected to a bottom flow port drive mechanism 22; the bottom flow port drive mechanism 22 is connected to a bottom flow port electric actuator 23; the bottom flow port drive mechanism 22 is connected to a bottom heavy sludge discharge port 18. The bottom heavy sludge discharge port 18 and the heavy sludge receiving flange 9 are vertically coaxial, and their connection method is as described above. Figure 10 The heavy sludge receiving flange 9 is connected to the heavy sludge discharge main pipe 19, from which the separated heavy sludge is discharged. The top light sludge discharge port 7 is connected to the light sludge discharge branch pipe 15; the light sludge discharge branch pipe 15 is freely placed in the inlet of the light sludge discharge main pipe 8. The light sludge discharge main pipe 8 is connected to the heavy sludge discharge flange interface 2. The sludge inlet sampling port 12 is installed on the flange opposite to the sludge inlet pipe connecting flange interface 1. The heavy sludge sampling port 13 is installed on the flange opposite to the heavy sludge discharge flange interface 2. The light sludge sampling port 14 is installed below the light sludge discharge flange interface 3. The sludge inlet main pipe 16 is horizontally fixed to the equipment skid 4 by pipe clamps; the heavy sludge discharge outlet main pipe 19 is horizontally fixed to the equipment skid 4 by pipe clamps; the light sludge discharge outlet main pipe 8 is fixed to the equipment skid 4 by pipe clamps; the cyclone separator 6 is fixed to the equipment skid 4 by pipe clamps; and the wind baffle 36 is installed on the outside of the equipment skid 4.

[0047] The dimensions of the flange interface 1 connecting the mud inlet pipe and the mud inlet main pipe 16 need to be adjusted according to the total water inlet flow rate to ensure that the liquid flow velocity in the pipe is within the range of 0.5~0.9 m / s.

[0048] The manual valve 5 of the mud inlet branch pipe is installed at the front end of the mud inlet branch pipe, and a pipe section distance of not less than 5 times the diameter of the mud inlet branch pipe is left between it and the installation position of the pressure gauge 11 of the mud inlet branch pipe.

[0049] The branch pipe 15 of the light sludge discharge outlet is a light flexible hose. One end of it is connected to the top light sludge discharge outlet 7 using a pipe clamp or clamp, and the other end is freely placed in the inlet of the main light sludge discharge outlet 8, so that the light sludge can flow freely under atmospheric pressure.

[0050] The heavy sludge receiving flange 9 and the heavy sludge discharge port 18 at the bottom of the hydrocyclone 6 are installed along the same vertical axis and do not contact each other, but are spaced about 100~200 mm apart, so that the heavy sludge can flow freely under atmospheric pressure.

[0051] like Figure 1 , 7 As shown in Figures 8 and 9, the number of cyclone separators 6 is 3, 4 or 5, which can be adjusted as needed.

[0052] The hydrocyclone separator 6 comes in two sizes: the smaller model has a cylinder section 20 with a diameter of 80mm~100mm and a water processing capacity of 0-10 m³. 3 / h; the diameter of the large-sized cylinder section 20 is 110mm~130mm, and the water treatment capacity is 10~30 m³ / h. 3 / h.

[0053] Both models of the hydrocyclone separator 6 have the following characteristics: the cone angle of the cone section 21 is 6°~9°, the cone ratio is in the range of 0.2~0.8, the depth of the top light sludge discharge port 7 inserted into the cylinder section 20 is 0.6~0.8 times the diameter of the cylinder section 20, the diameter of the part of the top light sludge discharge port 7 inserted into the cylinder section 20 is 0.2~0.4 times the diameter of the cylinder section 20, and the tangential sludge inlet 17 is circular and its diameter is 0.6~0.8 times the diameter of the cylinder section 20.

[0054] The hydrocyclone separator 6 is made of non-metallic materials such as polyurethane or corrosion-resistant metal materials.

[0055] The inner diameter of the bottom opening of the heavy sludge discharge port 18 can be adjusted by the underflow transmission mechanism 22 and the underflow electric actuator 23. The underflow diameter of the heavy sludge discharge port 18 can be adjusted within the range of 0.1 to 0.5 times the diameter of the cylindrical section 20. This is achieved by using a mixed sludge flow sensor 34 and a heavy sludge flow sensor 35 (these two sensors are described in detail below). Figure 11 The signal is provided to the main control room, and the main control room feeds back the signal to the bottom outlet electric actuator 23. The bottom outlet electric actuator 23 drives the bottom outlet transmission mechanism 22 to operate, thereby causing the heavy sludge discharge port 18 to contract or expand, controlling the flow ratio of the mixed sludge entering the cyclone separator 6 tangentially to the heavy sludge flowing out of the bottom of the cyclone separator 6 within the range of 5 to 20.

[0056] The heavy sludge receiving flange 9 serves as the heavy sludge receiving interface, and its interface diameter is 2 to 5 times the diameter of the bottom heavy sludge discharge port 18.

[0057] A wind deflector 36 is installed on the outside of the heavy sludge receiving flange 9 on the equipment skid 4.

[0058] After the sludge enters the heavy sludge screening device described in this embodiment, the following steps are used to separate the heavy sludge from the light sludge:

[0059] 1) Working process of the mixed sludge inlet section

[0060] The mixed sludge enters the device through the flange interface 1 of the inlet pipe. After passing through the inlet pressure sensor 10, it enters the main inlet pipe 16. Then, the mixed sludge is evenly distributed to each branch pipe through the manual valve 5 of the branch pipe, and the pressure of each branch pipe is adjusted to approximately equalize using the pressure gauge 11 of the branch pipe. Finally, it enters the sludge screening section through the tangential inlet 17. Samples can be taken from the mixed sludge through the inlet sampling port 12.

[0061] 2) Working process of sludge screening section

[0062] The mixed sludge enters the cylindrical section 20 of the hydrocyclone 6 through the tangential inlet 17. Under the influence of gravity, centrifugal force, and other forces, the mixed sludge first spirals downward along the inner wall of the cylindrical section 20. When it descends to the height of the conical section 21, due to the faster rotation speed of the liquid on the outer side and the slower rotation speed of the liquid on the inner side, a columnar low-pressure zone is formed in the center of the inner liquid. The lighter portion spirals upward along the central axis of the conical section 21, while the heavier portion continues to spiral downward along the inner wall of the conical section 21. The lighter portion flows to the top light sludge discharge port 7 and then enters the light sludge outlet section, while the heavier portion flows to the bottom heavy sludge discharge port 18 and then enters the heavy sludge outlet section. During the operation of the sludge screening section, the ratio of top overflow to bottom outflow is controlled by the bottom flow port drive mechanism 22 and the bottom flow port electric actuator 23. Specifically, the signals from the mixed sludge flow sensor 34 and the heavy sludge flow sensor 35 are transmitted to the control center. The control center calculates the ratio between the two and determines whether the flow ratio of mixed sludge to heavy sludge is within the range of 5 to 20. If it is greater than this range, it indicates that the bottom flow port is too small. The control center will transmit a signal to the bottom flow port electric actuator 23. The bottom flow port electric actuator 23 controls the bottom flow port drive mechanism 22 to drive the bottom heavy sludge discharge port 18 to expand the bottom flow port size until the flow ratio reaches the expected range, at which point the bottom flow port electric actuator 23 stops operating.

[0063] 3) Working process of the lightweight sludge outlet section

[0064] Light sludge enters the light sludge discharge branch pipe 15 through the top light sludge discharge port 7. The light sludge discharge branch pipe 15 is a flexible hose, with one end fixed to the top light sludge discharge port 7 and the other end freely placed at the inlet of the light sludge discharge main pipe 8, allowing the light sludge to flow freely in the light sludge discharge main pipe 8 under atmospheric pressure. The light sludge then flows through the light sludge discharge main pipe 8 to the light sludge discharge flange interface 3 and is discharged outside the equipment. Samples can be taken from the light sludge through the light sludge sampling port 14.

[0065] 4) Working process of the heavy sludge outlet section

[0066] Heavy sludge flows into the corresponding heavy sludge receiving flange 9 through the bottom heavy sludge discharge port 18 under gravity, then into the heavy sludge discharge main pipe 19, and finally flows out through the heavy sludge discharge flange interface 2, exiting the equipment. Samples can be taken from the heavy sludge through the heavy sludge sampling port 13.

[0067] Example 2:

[0068] This embodiment provides a method for screening heavy sludge using the aforementioned heavy sludge screening device. For example... Figure 11 As shown, the relative positions or connections of the various parts in the heavy sludge screening system of this embodiment are as follows: The biological treatment tank 25 is connected to the secondary sedimentation tank 26 via the first pipe 29 (in the water treatment industry, the secondary sedimentation tank refers to the sedimentation tank located after the biological treatment system; it can also be directly called the sedimentation tank here); the bottom of the secondary sedimentation tank 26 transports sludge to the sludge tank 27 via the second pipe 30; a submersible variable frequency sludge transfer pump 24 is installed at the bottom of the sludge tank 27; the variable frequency sludge transfer pump 24 transports sludge to the inlet pipe connection flange interface 1 of the heavy sludge screening device via the third pipe 31. A mixed sludge flow sensor 34 is installed on the third pipe 31. The heavy sludge discharge flange interface 2 is connected to the return sludge port of the biological treatment tank 25 via the fourth pipe 32. A heavy sludge flow sensor 35 is installed on the fourth pipe 32. The light sludge discharge flange interface 3 is connected to the sludge disposal device 28 via the fifth pipe 33, and the discharged light sludge is disposed of as waste sludge.

[0069] With a pressure of 0.15 MPa to 0.35 MPa, depending on the selected model, at a depth of 3 m 3 / h~200 m 3A flow rate of [flow rate] / h is fed into the heavy sludge screening device. After processing by the heavy sludge screening device, the denser and heavier activated sludge portion obtained from the heavy sludge screening device is returned to the biological treatment tank 25 for retention, while the lighter and looser sludge portion (such as filamentous bacteria) is discharged to the sludge disposal device 28 to be discharged from the activated sludge system. The heavy sludge has a higher density and better settling performance, and after being returned to the biological treatment tank 25, it helps to form granular sludge. After screening, the heavy sludge has an increased specific gravity and settling velocity, which can effectively improve the sludge settling performance; at the same time, the heavy sludge contains polyphosphate-accumulating bacteria (PAOs), ammonia-oxidizing bacteria (AOBs), nitrite-oxidizing bacteria (NOBs), denitrifying heterotrophic bacteria, and even anaerobic ammonia-oxidizing bacteria (Anammox), which can enhance the biological nitrogen and phosphorus removal capacity. During operation, water samples can be periodically taken from the sludge inlet 12, heavy sludge inlet 13, light sludge inlet 14, and the outlet of the biological treatment tank 25 to test dissolved oxygen, sludge TSS, sludge density, SVI, BOD, COD, NH3-N, and NO. x -N and parameters such as TN and TP were used to confirm the actual impact of the sludge screening system.

[0070] Figure 12-13 Table 1 shows some data obtained after applying this invention to the biochemical process section of a water plant. Figure 12 This is a comparison chart of SVI30 changes during a one-year experiment of the heavy sludge screening device of the present invention. Figure 13 This is a particle size distribution diagram of the heavy sludge screening device of the present invention. Table 1 is a data table of sludge particle density of the heavy sludge screening device of the present invention.

[0071] Table 1. Sludge particle density data for heavy sludge screening device

[0072]

[0073] according to Figure 12 , 13 As shown in Table 1, after at least two months of operation of the heavy sludge screener, the sludge settling performance was significantly improved and almost no longer affected by seasonal variations. This result can be explained by the fact that the sludge screener selectively removes the less dense portion of the mixed sludge from the biochemical system while retaining the denser portion inside. After five months of operation, the sludge density within the biochemical system increases. In addition, the particle size distribution of the screened heavy and light sludge differs, with the light sludge containing more sludge particles smaller than 200 micrometers. This demonstrates that the screening system can effectively separate and remove small sludge particles, leaving behind larger particles. Long-term operation can increase the proportion of large sludge particles in the system, which helps improve the sludge settling performance.

[0074] Obviously, the embodiments described above are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A heavy sludge screening device for a wastewater treatment system, characterized in that, The system includes a mixed sludge inlet section, a sludge screening section, a light sludge outlet section, a heavy sludge outlet section, and a supporting structure. The mixed sludge inlet section includes an inlet pipe connection flange interface (1), an inlet pressure sensor (10), an inlet main pipe (16), an inlet sampling port (12), an inlet branch pipe manual valve (5), and an inlet branch pipe pressure gauge (11). The sludge screening section includes a hydrocyclone separator (6), which is equipped with a tangential inlet (17) and a top light sludge outlet. The outlet (7) and bottom heavy sludge discharge outlet (18); the light sludge outlet section includes a light sludge discharge outlet branch pipe (15), a light sludge discharge outlet main pipe (8), a light sludge sampling port (14), and a light sludge discharge flange interface (3); the heavy sludge outlet section includes a heavy sludge receiving flange (9), a heavy sludge discharge outlet main pipe (19), a heavy sludge sampling port (13), and a heavy sludge discharge flange interface (2); the support structure includes an equipment skid (4); wherein: The inlet pipe is connected to the flange interface (1) and the inlet pressure sensor (10) is connected; the inlet pressure sensor (10) is connected to the inlet main pipe (16); the inlet main pipe (16) is connected to the inlet branch manual valve (5); the inlet branch manual valve (5) is connected to the inlet branch pressure gauge (11) through the pipe; the inlet branch pressure gauge (11) is connected to the tangential inlet (17); the bottom heavy sludge discharge port (18) and the heavy sludge receiving flange (9) are vertically coaxial; the heavy sludge receiving flange (9) is connected to the heavy sludge discharge port main pipe (19); the top light sludge discharge port (7) is connected to the light sludge discharge port branch pipe (15); the light sludge discharge port branch pipe (15) is freely placed at the inlet of the light sludge discharge port main pipe (8). In the middle; the light sludge discharge port main pipe (8) is connected to the light sludge discharge flange interface (3); the sludge inlet sampling port (12) is installed on the flange opposite to the sludge inlet pipe connection flange interface (1); the heavy sludge sampling port (13) is installed on the flange opposite to the heavy sludge discharge flange interface (2); the light sludge sampling port (14) is installed on the lower side of the light sludge discharge flange interface (3); the sludge inlet main pipe (16), the heavy sludge discharge port main pipe (19), the light sludge discharge port main pipe (8), and the cyclone separator (6) are fixed on the equipment skid (4); the heavy sludge discharge flange interface (2) is connected to the return sludge port of the biological treatment tank (25) through a pipe; the light sludge discharge flange interface (3) is connected to the sludge treatment device (28) through a pipe; The main body of the hydrocyclone separator (6) is assembled from an upper cylindrical section (20) and a lower conical section (21); the bottom of the hydrocyclone separator (6) is provided with a bottom flow port drive mechanism (22) and a bottom flow port electric actuator (23), the bottom flow port drive mechanism (22) is connected to the bottom flow port electric actuator (23), and the bottom flow port drive mechanism (22) is connected to the bottom heavy sludge discharge port (18); the bottom inner diameter of the bottom heavy sludge discharge port (18) can be connected to the bottom flow port drive mechanism (22) and the bottom flow port electric actuator (23). 3) Adjustments are made as follows: the mixed sludge flow sensor (34) and the heavy sludge flow sensor (35) provide signals to the main control room, the main control room feeds back signals to the bottom outlet electric actuator (23), the bottom outlet electric actuator (23) drives the bottom outlet transmission mechanism (22) to perform actions, thereby causing the heavy sludge discharge port (18) to contract or expand, so that the flow ratio of the mixed sludge entering the cyclone separator (6) tangentially and the heavy sludge flowing out from the bottom of the cyclone separator (6) is controlled within the range of 5 to 20.

2. The heavy sludge screening device for a wastewater treatment system according to claim 1, characterized in that: The hydrocyclone separator (6) comes in two sizes. The required number of large or small hydrocyclones is determined according to the amount of sludge to be screened. The diameter of the cylindrical section (20) of the small hydrocyclone separator is 80mm to 100mm, and the water treatment capacity is 0-10m³. 3 / h; The diameter of the cylindrical section (20) of the large-scale hydrocyclone separator is 110mm~130mm, and the water treatment capacity is 10~30m³. 3 / h; Both models have the following characteristics: the cone angle of the cone section (21) is 6° to 9°, the cone ratio is in the range of 0.2 to 0.8, the depth of the top light sludge discharge port (7) inserted into the cylinder section (20) is 0.6 to 0.8 times the diameter of the cylinder section (20), the diameter of the part of the top light sludge discharge port (7) inserted into the cylinder section (20) is 0.2 to 0.4 times the diameter of the cylinder section (20), and the tangential sludge inlet (17) is circular and its diameter is 0.6 to 0.8 times the diameter of the cylinder section (20).

3. The heavy sludge screening device for a wastewater treatment system according to claim 1, characterized in that: The dimensions of the mud inlet pipe connecting flange interface (1) and the mud inlet main pipe (16) are adjusted according to the total water inlet flow rate to ensure that the liquid flow velocity in the pipe is within the range of 0.5 to 0.9 m / s.

4. The heavy sludge screening device for a wastewater treatment system according to claim 1, characterized in that: The manual valve (5) of the mud inlet branch pipe is installed at the front end of the mud inlet branch pipe, and a pipe section distance of not less than 5 times the diameter of the mud inlet branch pipe is left between it and the installation position of the pressure gauge (11) of the mud inlet branch pipe.

5. The heavy sludge screening device for a wastewater treatment system according to claim 1, characterized in that: The branch pipe (15) of the light sludge discharge outlet is a light hose. One end of it is connected to the top light sludge discharge outlet (7) using a pipe clamp or clamp, and the other end is freely placed in the inlet of the main pipe (8) of the light sludge discharge outlet, so that the light sludge can flow freely under atmospheric pressure.

6. The heavy sludge screening device for a wastewater treatment system according to claim 1, characterized in that: The heavy sludge receiving flange (9) and the heavy sludge discharge port (18) at the bottom of the cyclone separator (6) are installed along the same vertical axis and do not contact each other, so that the heavy sludge can flow freely under atmospheric pressure. The heavy sludge receiving flange (9) serves as the heavy sludge receiving interface, and its interface diameter is 2 to 5 times the diameter of the bottom heavy sludge discharge port (18).

7. The heavy sludge screening device for a wastewater treatment system according to claim 1, characterized in that: The equipment skid includes a wind deflector, which is installed on the outside of the heavy sludge receiving flange (9).

8. A method for screening heavy sludge using the heavy sludge screening device for a wastewater treatment system according to any one of claims 1 to 7, characterized in that, Includes the following steps: 1) Mixed sludge inlet section: The mixed sludge enters the heavy sludge screening device from the sludge inlet pipe connecting flange interface (1). After passing the sludge inlet pressure sensor (10), it enters the sludge inlet main pipe (16). Then, the mixed sludge is evenly distributed to each sludge inlet branch pipe through the sludge inlet branch pipe manual valve (5). The pressure of each branch pipe is adjusted to be roughly balanced by the sludge inlet branch pipe pressure gauge (11). Finally, it enters the sludge screening section through the tangential sludge inlet (17). 2) Sludge screening section: Mixed sludge enters the hydrocyclone separator (6) through the tangential sludge inlet (17). The lighter part flows to the top light sludge discharge port (7) and then enters the light sludge outlet section. The heavier part flows to the bottom heavy sludge discharge port (18) and then enters the heavy sludge outlet section. 3) Light sludge outlet section: Light sludge enters the light sludge outlet branch pipe (15) through the top light sludge outlet (7). The light sludge flows freely in the light sludge outlet main pipe (8) under atmospheric pressure. Then the light sludge flows through the light sludge outlet main pipe (8) to the light sludge outlet flange interface (3) and is discharged, discharging the light sludge to the sludge treatment device. 4) Heavy sludge outlet section: Heavy sludge flows into the corresponding heavy sludge receiving flange (9) through the bottom heavy sludge discharge port (18) by gravity, and then flows into the heavy sludge discharge port main pipe (19), and finally is discharged through the heavy sludge discharge flange interface (2), returning the heavy sludge to the biological treatment tank for retention.

9. The method for screening heavy sludge according to claim 8, characterized in that: A variable frequency sludge transfer pump is used to transfer the return sludge or excess sludge discharged from the secondary sedimentation tank at a pressure of 0.15MPa to 0.35MPa, at a speed of 3m. 3 / h~200m 3 A flow rate of / h is fed into the heavy sludge screening device.

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