A system and method for improving the settleability of raw, ponded sludge

Abstract

The present application belongs to the field of environmental protection, and particularly relates to a system and method for improving the sedimentation performance of raw sludge. The system comprises a biochemical tank, a sedimentation tank connected with a sludge-water mixture outlet of the biochemical tank, a sludge feeding pump connected with a sludge discharge outlet of the sedimentation tank, a cyclone separator connected with an outlet of the sludge feeding pump, a bottom flow outlet of the cyclone separator connected back to the biochemical tank, a sludge discharge pump connected with an overflow outlet of the cyclone separator, and a control module for controlling the start and stop of the sludge feeding pump, the cyclone separator and the sludge discharge pump. The system can separate heavy sludge and light sludge by means of the cyclone separator, thereby effectively improving the sedimentation performance of raw sludge; and the system can be automatically controlled by the control module, and has low dependence on manual operation.

Description

Technical Field

[0001] This invention belongs to the field of environmental protection, and in particular relates to a system and method for improving the settling properties of sludge produced in biological ponds. Background Technology

[0002] The activated sludge process is a primary method of biological wastewater treatment, primarily using activated sludge. In this process, air is continuously introduced into the wastewater, and after a certain period, aerobic microorganisms multiply, forming sludge-like flocs. These flocs are inhabited by a microbial community, mainly composed of bacterial flocs, which have a strong ability to adsorb and oxidize organic matter. The activated sludge utilizes its bio-flocculation, adsorption, and oxidation processes to decompose and remove organic pollutants from the wastewater. The sludge is then separated from the water in a sedimentation tank; most of the sludge is returned to the biological treatment tank, while the excess is discharged from the activated sludge system.

[0003] Currently, most wastewater treatment plants in China suffer from poor sludge settling properties in their activated sludge treatment systems, leading to a series of problems such as excessive load on sedimentation tanks, persistently high sludge concentrations, and declining effluent quality. Therefore, improving the settling properties of activated sludge in biological treatment tanks is a pressing issue that needs to be addressed in this field. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a system and method for improving the settling properties of sludge produced in a biological pond. The system provided by the present invention can separate heavy sludge and light sludge by means of a hydrocyclone separator, thereby effectively improving the settling properties of sludge produced in a biological pond. Moreover, the system can be automatically controlled by a control module, with low dependence on manual labor.

[0005] This invention provides a system for improving the settling properties of sludge in biological treatment ponds, comprising:

[0006] Biochemical pool;

[0007] A sedimentation tank whose inlet is connected to the outlet of the mud-water mixture of the biological treatment tank;

[0008] A sludge pump whose inlet is connected to the sludge discharge port of the sedimentation tank;

[0009] A hydrocyclone separator with its inlet connected to the outlet of the sludge pump, and the underflow outlet of the hydrocyclone separator connected back to the biological treatment tank;

[0010] A sludge pump whose inlet is connected to the overflow port of the cyclone separator;

[0011] And a control module for controlling the start and stop of the mud inlet pump, cyclone separator and mud outlet pump.

[0012] Preferably, the diameter of the cylindrical section of the cyclone separator is 100-300 mm; the height of the cylindrical section of the cyclone separator is 100-300 mm.

[0013] Preferably, the cone section length of the cyclone separator is 1000–1500 mm.

[0014] Preferably, the inlet of the cyclone separator is square with a side length of 13–90 mm.

[0015] Preferably, the inner diameter of the overflow port of the cyclone separator is 40-70 mm; the depth of the overflow pipe of the cyclone separator is 50-270 mm; and the wall thickness of the overflow port of the cyclone separator is 10-15 mm.

[0016] Preferably, the inner diameter of the underflow port of the cyclone separator is 10-35 mm; the wall thickness of the underflow port of the cyclone separator is 10-15 mm.

[0017] Preferably, the outflow state of the underflow port of the cyclone separator is spiral.

[0018] Preferably, the system further includes a residual sludge channel, the inlet of which is connected to the outlet of the sludge pump.

[0019] This invention provides a method for improving the settling properties of sludge in a biological treatment tank, carried out in the system described above, and includes the following processes:

[0020] A set value for the biological sludge settling index is set. When the difference between the measured value of the sludge settling index of the biological tank and the set value exceeds the preset range, the sludge inlet pump, cyclone separator and sludge outlet pump are started through the control module.

[0021] After the sludge inlet pump, hydrocyclone separator and sludge outlet pump are started, the sludge-water mixture discharged from the sedimentation tank is pumped into the hydrocyclone separator for separation by the sludge inlet pump. The heavy sludge-water mixture obtained by separation is returned to the biological treatment tank, and the light sludge obtained by separation is discharged by the sludge outlet pump.

[0022] During the continuous reflux of the heavy sludge-water mixture into the biological treatment tank, the difference between the measured value of the sludge settling index and the set value gradually decreases. Once the difference falls within a preset range, and the sludge settling ratio SV5 and sludge settling ratio SV5 in the biological treatment tank are... 30 When the difference is within the preset range, the sludge inlet pump, hydrocyclone separator and sludge outlet pump are shut down through the control module.

[0023] The present invention also provides another method for improving the settling properties of sludge in a biological treatment tank in the system described above, comprising the following steps:

[0024] The settling index of the sludge at the underflow outlet of the hydrocyclone is measured, and a set value for the sludge settling index at the underflow outlet is set. If the ratio of the difference between the sludge settling index at the underflow outlet and the set value for sludge settling at the underflow outlet to the set value for sludge settling at the underflow outlet exceeds a preset range, the sludge inlet pump, the hydrocyclone separator, and the sludge outlet pump are started through the control module.

[0025] After the sludge inlet pump, hydrocyclone separator, and sludge discharge pump are started, the sludge-water mixture discharged from the sedimentation tank is pumped into the hydrocyclone separator for separation by the sludge inlet pump. The heavy sludge-water mixture obtained by separation is returned to the biological treatment tank, and the light sludge obtained by separation is discharged by the sludge discharge pump.

[0026] Compared with existing technologies, the present invention provides a system and method for improving the settling properties of sludge from biological treatment ponds. The system provided by the present invention includes: a biological treatment pond; a sedimentation tank with its inlet connected to the outlet of the sludge-water mixture of the biological treatment pond; a sludge inlet pump with its inlet connected to the sludge discharge outlet of the sedimentation tank; a hydrocyclone separator with its inlet connected to the outlet of the sludge inlet pump, the underflow outlet of the hydrocyclone separator being connected back to the biological treatment pond; a sludge discharge pump with its inlet connected to the overflow outlet of the hydrocyclone separator; and a control module for controlling the start and stop of the sludge inlet pump, the hydrocyclone separator, and the sludge discharge pump. The specific process of improving the sludge settling properties of the biological treatment tank using this system includes: setting a set value for the biological sludge settling index; when the difference between the measured value of the sludge settling index of the biological treatment tank and the set value exceeds a preset range, the sludge inlet pump, cyclone separator, and sludge outlet pump are started through the control module; after the sludge inlet pump, cyclone separator, and sludge outlet pump are started, the sludge-water mixture discharged from the sedimentation tank is pumped into the cyclone separator for separation by the sludge inlet pump; the separated heavy sludge-water mixture is returned to the biological treatment tank, and the separated light sludge is discharged by the sludge outlet pump; during the continuous return of the heavy sludge-water mixture to the biological treatment tank, the difference between the measured value of the sludge settling index of the biological treatment tank and the set value gradually decreases until the difference is within the preset range, and the sludge settling ratio SV5 and sludge settling ratio SV5 of the biological treatment tank are within the preset range. 30 When the difference is within a preset range, the sludge inlet pump, cyclone separator, and sludge outlet pump are shut down via the control module. The system provided by this invention can separate heavy and light sludge using a cyclone separator, thereby effectively improving the settling properties of biological sludge. Furthermore, the system can be automated through the control module, reducing reliance on manual intervention. The system provided by this invention has a clear principle, stable operation, and low cost. It can significantly improve the settling properties of biological sludge, thereby enhancing the treatment effect of the activated sludge process. It can be widely applied in wastewater treatment plants using existing activated sludge processes, and has a broad market prospect. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0028] Figure 1 This is a basic system framework diagram provided in the embodiments of the present invention;

[0029] Figure 2 This is a schematic diagram of the cyclone separator structure provided in an embodiment of the present invention;

[0030] Figure 3 This is a graph showing the change of the settlement index with the number of treatment days provided in an embodiment of the present invention;

[0031] Figure 4 This is a graph showing the change in the settling ratio with the number of treatment days provided in an embodiment of the present invention.

[0032] Appendix Figure 2 The markings are as follows: 1 is the inlet, 2 is the overflow outlet, and 3 is the bottom outlet. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] This invention provides a system for improving the settling properties of sludge in biological treatment ponds, see [link to relevant documentation]. Figure 1 It includes: a biological treatment tank, a sedimentation tank, a sludge inlet pump, a hydrocyclone separator, a sludge discharge pump, and a control module, and preferably also includes a residual sludge channel.

[0035] In the system provided by the present invention, the biochemical tank is the main equipment for biochemical treatment of sewage, and it is equipped with an inlet, an aeration port, a mud-water mixture outlet and a sludge return port.

[0036] In the system provided by the present invention, the sedimentation tank is used to separate the mud and water mixture discharged from the biological treatment tank, that is, to perform preliminary sorting of the mud and water mixture. It is provided with an inlet, an outlet and a sludge discharge outlet. The inlet of the sedimentation tank is connected to the outlet of the mud and water mixture of the biological treatment tank.

[0037] In the system provided by the present invention, the sludge pump is used to pump the mud-water mixture discharged from the sludge outlet of the sedimentation tank into a hydrocyclone separator, which is provided with an inlet and an outlet, and the inlet of the sludge pump is connected to the sludge outlet of the sedimentation tank.

[0038] In the system provided by the present invention, the hydrocyclone separator can separate the mud-water mixture discharged from the sludge discharge port of the sedimentation tank by means of the specific gravity difference, and obtain a heavy mud-water mixture with better settling properties and a light mud-water mixture (sludge) with poor settling properties respectively. It is provided with an inlet, an overflow port (light outlet) and a bottom outlet (heavy outlet). The inlet of the hydrocyclone separator is connected to the outlet of the sludge pump, and the bottom outlet of the hydrocyclone separator is connected back to the biological treatment tank.

[0039] In the system provided by the present invention, the structure of the cyclone separator is preferably as follows: Figure 2 As shown, it includes: a shell, an inlet 1 located at the top of the shell, a bottom outlet 3 located at the bottom of the shell, and an overflow pipe with one end on the outside of the shell and the other end extending from the top of the shell into the interior of the shell; wherein, the upper half of the shell is a cylindrical section and the lower half is a conical section; the inlet 1 is located on the top side wall of the cylindrical section; the outlet end of the overflow pipe is the overflow outlet 2, and the inlet end extends into the interior of the cylindrical section; the bottom outlet 3 is located at the bottom end of the conical section.

[0040] In the system provided by the present invention, the diameter (D) of the cylindrical section of the cyclone separator is preferably 100-300 mm; the height (H) of the cylindrical section of the cyclone separator is preferably 100-300 mm; and the mathematical relationship between the diameter (D) and the height (H) of the cylindrical section is preferably H = (0.8-1.2) × D.

[0041] In the system provided by the present invention, the cone length of the cyclone separator is preferably 1000-1500 mm.

[0042] In the system provided by this invention, the inlet 1 of the cyclone separator is preferably square, more preferably square; the side length of the inlet 1 of the cyclone separator is preferably 13-90 mm; the diameter (D) of the inlet 1 of the cyclone separator is... i The preferred mathematical relationship between the diameter (D) of the cylindrical segment and the diameter (D) is D. i = (0.13~0.29)×D.

[0043] In the system provided by this invention, the inner diameter (D) of the overflow port 2 of the cyclone separator o The preferred length is 40–70 mm; the overflow pipe depth of the cyclone separator (L) o The preferred length is 50–270 mm; the overflow pipe depth length (L) o The preferred mathematical relationship between L and the diameter (D) of the cylindrical segment is L. o= (0.5~0.9)×D; The wall thickness of the overflow port 2 of the cyclone separator is preferably 10~15mm.

[0044] In the system provided by this invention, the inner diameter (D) of the underflow port 3 of the cyclone separator u The preferred diameter is 10–35 mm; the inner diameter (D) of the underflow outlet 3 of the cyclone separator u ) and the inner diameter of the overflow port 2 of the cyclone separator (D) o The preferred mathematical relationship is D. u = (0.2~0.4)×D o The wall thickness of the underflow port of the cyclone separator is preferably 10-15 mm; the outflow state of the underflow port of the cyclone separator is preferably spiral.

[0045] In the system provided by this invention, the dimensions of each part of the cyclone separator are optimized, particularly based on the mathematical relationships mentioned above, for the diameter (D) of the cylindrical section (H) and the height (H) of the cylindrical section, and the depth (L) of the overflow pipe. o ), Overflow port 2 inner diameter (D) o ), inner diameter of bottom flow port 3 (D u By optimizing the design, the internal structure of the cyclone separator can be made so that a central cone is not required.

[0046] In the system provided by the present invention, the material of the cyclone separator is preferably polyurethane or other similarly shaped materials.

[0047] In the system provided by this invention, the operating pressure of the cyclone separator is preferably 0.01–0.16 MPa; the throughput of the cyclone separator is preferably 30–80 m³ / s. 3 / h.

[0048] In the system provided by the present invention, the sludge pump is used to pump out the light sludge discharged from the overflow port of the hydrocyclone separator. It is provided with an inlet and an outlet, and the inlet of the sludge pump is connected to the overflow port of the hydrocyclone separator.

[0049] In the system provided by this invention, the control module is used to control the start and stop of the sludge pump, the hydrocyclone separator and the sludge discharge pump, thereby realizing the automated control of the system and reducing the dependence on manual labor.

[0050] In the system provided by the present invention, the residual sludge channel is an external discharge and conveying channel for the light sludge discharged from the overflow port of the hydrocyclone separator, and its inlet is connected to the outlet of the sludge discharge pump.

[0051] The present invention also provides a method for improving the settling properties of sludge in a biological treatment tank, which is carried out in the system described in the above technical solution and includes the following processes:

[0052] Set a set value for the biological sludge settling index (SVI). 生化污泥设定 When the measured value of the sludge settling index (SVI) in the biological treatment tank... 生化污泥实测 ) and the set value (SVI) 生化污泥设定 When the difference exceeds the preset range, the sludge pump, hydrocyclone separator and sludge discharge pump are started through the control module;

[0053] After the sludge inlet pump, hydrocyclone separator and sludge outlet pump are started, the sludge-water mixture discharged from the sedimentation tank is pumped into the hydrocyclone separator for separation by the sludge inlet pump. The heavy sludge-water mixture obtained by separation is returned to the biological treatment tank, and the light sludge obtained by separation is discharged by the sludge outlet pump.

[0054] During the continuous return of the heavy sludge-water mixture to the biological treatment tank, the measured sludge settling index (SVI) of the biological treatment tank was... 生化污泥实测 ) and the set value (SVI) 生化污泥设定 The difference between the sludge settling ratio SV5 and the sludge settling ratio SV in the biological treatment tank gradually decreases until the difference is within a preset range. 30 When the difference is within the preset range, the sludge inlet pump, hydrocyclone separator and sludge outlet pump are shut down through the control module.

[0055] The present invention also provides another method for improving the settling properties of sludge in a biological treatment tank in the system described above, comprising the following steps:

[0056] The settling index of the sludge at the underflow outlet of the hydrocyclone is measured, and a set value for the sludge settling index at the underflow outlet is set. If the ratio of the difference between the sludge settling index at the underflow outlet and the set value for sludge settling at the underflow outlet to the set value for sludge settling at the underflow outlet exceeds a preset range, the sludge inlet pump, the hydrocyclone separator, and the sludge outlet pump are started through the control module.

[0057] After the sludge inlet pump, hydrocyclone separator, and sludge discharge pump are started, the sludge-water mixture discharged from the sedimentation tank is pumped into the hydrocyclone separator for separation by the sludge inlet pump. The heavy sludge-water mixture obtained by separation is returned to the biological treatment tank, and the light sludge obtained by separation is discharged by the sludge discharge pump.

[0058] In the method provided by the present invention, the sedimentation index (SVI) is defined as the volume of precipitated sludge formed per gram of dry sludge after the sludge-water mixture has settled for 30 minutes, expressed in mL / g.

[0059] In the method provided by this invention, the sludge settling ratio SV5, also known as the 5-minute settling rate, is defined as the percentage of the volume of precipitated sludge formed after the mud-water mixture has been left to stand in a graduated cylinder for 5 minutes, expressed as a percentage.

[0060] In the method provided by this invention, the sludge settling ratio SV 30 Also known as the 30-minute settling rate, it is defined as the percentage of the volume of precipitated sludge formed after the mud-water mixture has been left to stand in a graduated cylinder for 30 minutes, relative to the original volume of the mixed liquid, expressed as a percentage.

[0061] In the method provided by this invention, the sludge settling index fluctuation value α can be calculated as an indicator reflecting the fluctuation of the sludge settling index of the system under ideal conditions. The calculation formula is as follows:

[0062]

[0063] In equation (1), α is the sludge settling index fluctuation value, in %; SVI 底流出口设定 This is the setpoint for the sludge settling index (SVI) at the underflow outlet of the hydrocyclone separator, in mL / g. 生化污泥设定 It is the set value of the biological sludge settling index, in mL / g.

[0064] In the method provided by this invention, the measured value of the sludge settling index (SVI) in the biological treatment tank is... 生化污泥实测 ) and the set biological sludge settling index (SVI) 生化污泥设定 The inherent relationship between these factors is one of the keys to determining the mature and stable operation of a hydrocyclone separator. During the continuous return of the heavy sludge-water mixture to the biological treatment tank, the SVI... 生化污泥实测 With SVI 生化污泥设定 The difference gradually decreases, and when the time is long enough, the difference approaches 0. Therefore, based on relevant experience, a range for the difference fluctuation can be pre-set, for example, ≤±2mL / g. When the difference is within this range, the hydrocyclone separator can be judged to be operating maturely and stably, and vice versa. In this invention, the absolute value β of the difference can also be used as a technical indicator for judging whether the hydrocyclone separator is operating maturely and stably. The calculation formula is as follows:

[0065] β=|SVI 生化污泥实测 -SVI 生化污泥设定 | Equation (2);

[0066] In formula (2), β is the absolute value of the difference between the measured value of the sludge settling index of the biological treatment tank and the set value of the biological sludge settling index, in mg / L; SVI 生化污泥实测 This is the measured value of the sludge settling index (SVI) in the biological treatment tank, in mg / L. 生化污泥设定 It is the set value of the biological sludge settling index, in mL / g.

[0067] In the method provided by the present invention, the working status and operating effect of the cyclone separator during the system operation can be evaluated based on either the α value or the β value, or the working status and operating effect of the cyclone separator during the system operation can be evaluated based on a combination of the α value and the β value.

[0068] In the method provided by this invention, the settling ratios of the sludge in the biological treatment tank are SV5 and SV2. 30 It is an important parameter characterizing the settling performance of activated sludge in biological treatment tanks, and SV5 and SV 30 The difference between SV5 and SV is an important parameter characterizing the stability of sludge in biological treatment tanks. When SV5 is close to SV... 30 When the difference is within a certain range, the sludge in the biological treatment tank can be determined to be stable. Therefore, based on relevant experience, a range for the difference fluctuation can be preset, for example, ≤2%. When the difference is within this range, the sludge in the biological treatment tank can be determined to be stable, and vice versa.

[0069] In the method provided by the present invention, when it is determined that both the hydrocyclone separator and the sludge in the biological treatment tank are operating stably, the sludge inlet pump, the hydrocyclone separator and the sludge outlet pump are shut down by the control module.

[0070] The system and method for improving the settling properties of sludge in biological treatment ponds provided by this invention can effectively improve the settling properties of sludge by separating heavy and light sludge using a hydrocyclone separator. Furthermore, this solution can be automated through a control module, reducing reliance on manual intervention. The system and method provided by this invention have a clear principle, stable operation, and low cost. They can significantly improve the settling properties of biological sludge, thereby enhancing the treatment efficiency of the activated sludge process. This invention can be widely applied to wastewater treatment plants using existing activated sludge processes, and has a broad market prospect.

[0071] For clarity, the following examples will be used to provide a detailed description.

[0072] Example 1

[0073] exist Figure 1 The system shown improves the settling properties of sludge in the biological treatment tank. The system includes: a biological treatment tank, a sedimentation tank, a sludge inlet pump, a hydrocyclone separator, a sludge discharge pump, a control module, and a waste sludge channel. The location and connection relationship of each device and equipment have been described above and will not be repeated here.

[0074] In this embodiment, the structure of the cyclone separator is as follows: Figure 2 As shown, its parameter specifications are as follows:

[0075] Cylindrical section diameter D: 200mm;

[0076] Cylindrical section height H: 200mm;

[0077] Bottom flow port inner diameter D u 20mm;

[0078] Underflow outlet wall thickness: 15mm;

[0079] Overflow port inner diameter D o 50mm;

[0080] Overflow pipe depth L o 150mm;

[0081] Overflow port wall thickness 10mm;

[0082] Conical section length: 1200mm;

[0083] Inlet inner diameter: 40×40mm, square;

[0084] Bottom outflow pattern: spiral sludge discharge;

[0085] Presence or absence of a central cone: No;

[0086] Material: Polyurethane;

[0087] Working pressure: 0.1 MPa;

[0088] Processing capacity: 50m 3 / h.

[0089] In this embodiment, the system operates as follows:

[0090] Set the setpoint for the biological sludge settling index (SVI). 生化污泥设定 = 81 mL / g, when the measured value of the sludge settling index (SVI) in the biological treatment tank is... 生化污泥实测 ) and SVI 生化污泥设定 When the difference exceeds 5 mL / g, the sludge inlet pump, hydrocyclone separator and sludge outlet pump are started through the control module;

[0091] After the sludge inlet pump, hydrocyclone separator, and sludge outlet pump are started, the sludge (sludge-water mixture) discharged from the sedimentation tank is pumped into the hydrocyclone separator for separation via the sludge inlet pump. The sludge settling index (SVI) setpoint at the bottom outlet of the hydrocyclone separator is determined. 底流出口设定 =60mL / g; After the mud-water mixture is separated by a hydrocyclone separator, the heavy mud-water mixture with better settling properties discharged from the underflow outlet is returned to the biological treatment tank, while the light mud-water mixture (sludge) with poor settling properties discharged from the overflow outlet is transported to the excess sludge channel by a sludge discharge pump.

[0092] During the continuous reflux of the heavy sludge-water mixture into the biological treatment tank, the SVI of the biological treatment tank... 生化污泥实测 With SVI 生化污泥设定 The difference gradually decreases until the absolute value of the difference (β) is ≤ 1 mL / g, and the sludge settling ratio of the biological treatment tank SV5 to SV5 is... 30 When the difference is ≤1%, the sludge settling properties in the system are considered to be good and stable; subsequently, the sludge inlet pump, cyclone separator and sludge outlet pump are shut down through the control module.

[0093] In this embodiment, the settling properties of the biological treatment tank sludge with an initial settling index (SVI) of 100 mL / g were improved according to the above operating procedure, with α = 26%. After 25 days of system operation, the SVI... 生化污泥实测 =81mL / g, β=0mL / g, sludge settling ratio SV5 and SV in biological treatment tank 30 The concentrations were 30% and 31% respectively (difference of 1%), and the sludge concentration decreased to 3700 mg / L. It can be seen that the sludge in the biological treatment tank has good and stable settling properties. At this time, the sludge inlet pump, cyclone separator and sludge outlet pump were shut down by the control module.

[0094] In this embodiment, the measured values ​​of the sludge settling index at the underflow outlet of the hydrocyclone separator and the biological treatment tank during system operation vary with the number of treatment days as follows: Figure 3 As shown.

[0095] In this embodiment, during system operation, the sludge settling ratios SV5 and SV in the biological treatment tank are... 30 The variation with the number of processing days is as follows: Figure 4 As shown.

[0096] As can be seen from Embodiment 1 provided by the present invention, the system provided by the present invention can effectively improve the settling properties of biological sludge and enable the improved biological tank to enter a stable operating period in a short period of time.

[0097] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for improving the settling properties of sludge in a biological treatment tank, characterized in that, A system for improving the settling properties of sludge in a biological treatment tank is employed, comprising: Biochemical pool; A sedimentation tank whose inlet is connected to the outlet of the mud-water mixture of the biological treatment tank; A sludge pump whose inlet is connected to the sludge discharge port of the sedimentation tank; A hydrocyclone separator with its inlet connected to the outlet of the sludge pump, and the underflow outlet of the hydrocyclone separator connected back to the biological treatment tank; A sludge pump whose inlet is connected to the overflow port of the cyclone separator; And a control module for controlling the start and stop of the mud inlet pump, hydrocyclone separator and mud outlet pump; The diameter of the cylindrical section of the cyclone separator is 100~300mm; the height of the cylindrical section of the cyclone separator is 100~300mm. The cone section of the cyclone separator has a length of 1000 ~ 1500 mm; The inlet of the cyclone separator is square, with a side length of 13 to 90 mm; The overflow port inner diameter of the cyclone separator is 40-70mm; the overflow pipe depth of the cyclone separator is 50-270mm; and the overflow port wall thickness of the cyclone separator is 10-15mm. The inner diameter of the underflow inlet of the cyclone separator is 10-35 mm; the wall thickness of the underflow inlet of the cyclone separator is 10-15 mm. The cyclone separator has no central cone inside; The method for improving the settling properties of sludge in a biological treatment tank includes the following steps: A set value for the biological sludge settling index is set. When the difference between the measured value of the sludge settling index of the biological tank and the set value exceeds the preset range, the sludge inlet pump, cyclone separator and sludge outlet pump are started through the control module. After the sludge inlet pump, hydrocyclone separator and sludge outlet pump are started, the sludge-water mixture discharged from the sedimentation tank is pumped into the hydrocyclone separator for separation by the sludge inlet pump. The heavy sludge-water mixture obtained by separation is returned to the biological treatment tank, and the light sludge obtained by separation is discharged by the sludge outlet pump. During the continuous reflux of the heavy sludge-water mixture into the biological treatment tank, the difference between the measured value of the sludge settling index and the set value gradually decreases. Once the difference falls within a preset range, and the sludge settling ratio SV5 and sludge settling ratio SV5 in the biological treatment tank are... 30 When the difference is within the preset range, the sludge inlet pump, hydrocyclone separator and sludge outlet pump are shut down through the control module.

2. The method for improving the settling properties of sludge in a biological treatment tank according to claim 1, characterized in that, It also includes a residual sludge channel, the inlet of which is connected to the outlet of the sludge pump.

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