Backwash solid-liquid separation system for anaerobic ammonia oxidation reactor

Abstract

The utility model relates to the technical field of solid-liquid separation systems, and discloses a backwash solid-liquid separation system for an anaerobic ammonia oxidation reactor, which comprises a reactor and a solid-liquid separation system, an overflow port is arranged at the top of the reactor, a water inlet is arranged at the bottom of the reactor, and a water outlet is arranged at the bottom of the reactor. A solid-liquid separation area is arranged on the inner side of the top of the reactor, and the solid-liquid separation system comprises a filtering assembly, a control pump assembly and a backwashing assembly. According to the utility model, the filter device is arranged in the reactor, and microorganisms on the surface of the filter screen in the filter device are continuously retained in the reactor under the action of sludge sedimentation and back flushing, so that the biological retention effect of the reactor is improved. And meanwhile, the service life and the separation effect of the filter screen can be further improved by backwashing with a certain frequency.

Description

Technical Field

[0001] The utility model relates to the technical field of solid-liquid separation systems, in particular to a solid-liquid separation system for backwashing an anaerobic ammonium oxidation reactor. Background Art

[0002] Anaerobic ammonium oxidizing bacteria is a slow-growing autotrophic bacteria with a doubling time of 2.1-11 days. During the actual operation or startup process, due to the scouring of the water flow and air flow of the bioreactor, the flocculent sludge is easily suspended in the effluent and flows out, resulting in the loss of microorganisms. Especially in the process of treating large-volume urban sewage, the retention of microorganisms is an engineering difficulty. In actual engineering, anaerobic ammonium oxidizing reactors mostly use three-phase separators to separate solids, liquids and gases. However, this method has limited effect on solid-liquid separation, and the separated solid-liquid mixture needs to be further filtered. However, the clogging of the filter screen caused by long-term filtration is a problem that still needs to be solved in engineering applications. Utility Model Content

[0003] In view of the deficiencies in the prior art, the utility model provides a solid-liquid separation system for backwashing of an anaerobic ammonium oxidation reactor, which solves the problems raised by the above-mentioned background technology.

[0004] The utility model provides the following technical solution: a solid-liquid separation system for backwashing of an anaerobic ammonium oxidation reactor, comprising a reactor and a solid-liquid separation system, wherein an overflow port is arranged at the top of the reactor, a water inlet is arranged at the bottom of the reactor, a solid-liquid separation zone is arranged inside the top of the reactor, and the solid-liquid separation system comprises a filter assembly, a control pump assembly, and a backwash assembly;

[0005] The filter assembly is mounted on the upper part of the solid-liquid separation zone of the reactor and below the liquid surface;

[0006] The control pump assembly is a pipeline pump equipped with a float switch, and the float switch is placed on the liquid surface of the liquid inside the reactor;

[0007] The backwashing assembly consists of a filtering device and an external thread interface sealed together, one end of the external thread interface is connected to a second connecting valve pipe, one end of the second connecting valve pipe extends to the outside of the reactor and is connected to a blower, the second connecting valve pipe is located on the pipeline structure outside the pipeline pump and is connected to the first connecting valve pipe, and one end of the first connecting valve pipe is connected to the input end of the pipeline pump.

[0008] The filter device is composed of a diamond-shaped supporting guard net and a filter net covered and wrapped on the surface of the diamond-shaped supporting guard net. The top of the diamond-shaped supporting guard net is connected to the other end of the external thread interface. The diamond-shaped supporting guard net is preferably made of stainless steel, which can support the annular filter net and prevent deformation during subsequent use.

[0009] The filter screen is a 20-80 mesh filter screen structure, and the surface of the filter screen is coated with an anti-corrosion coating to increase the service life, and the filter device is cylindrical as a whole, which can increase the contact area between the filter screen and the solid-liquid mixture and improve the filtering effect. The entire filter device is placed horizontally, which can minimize the water pressure difference at various locations of the filter screen.

[0010] The float switch is specially designed to set a maximum liquid level and a minimum liquid level for the liquid level in the reactor, and the maximum liquid level does not exceed the overflow port of the reactor, and the minimum liquid level does not fall below the filter device, so as to avoid the pipeline pump from pumping water while the filter is exposed to the air for idling and pumping air, thereby reducing damage to the pipeline pump.

[0011] Preferably, the tube body of the first connecting valve tube and the tube body of the second connecting valve tube are both made of hard tubes, and the valve on the tube body of the first connecting valve tube and the valve on the tube body of the second connecting valve tube are both solenoid valves, such as PVC tubes, and then the first connecting valve tube and the second connecting valve tube form a pipeline system in the overall device, which has the effect of resisting pressure and deformation under high water pressure and air pressure, and the use of the solenoid valve can provide structural conditions for the subsequent automatic adjustment of the overall device to achieve backwashing state and filtering and drainage state;

[0012] Preferably, a rotating support component, a transmission shaft, and an auxiliary cleaning component are mounted on the inner side of the middle part of the diamond-shaped supporting guard net, one side of the auxiliary cleaning component is fixedly connected to the surface of the transmission shaft, and the bottom end of the transmission shaft is mounted on the inner side of the rotating support component.

[0013] The rotating support component includes a T-shaped sleeve, a supporting bearing, and a sealing ring. The supporting bearing and the sealing ring are both mounted on the inner side of the middle part of the T-shaped sleeve. The inner ring structure of the supporting bearing and the inner side of the middle part of the sealing ring are both mounted on the surface of the bottom end of the transmission shaft. The rotating support component provides support for the rotation operation of the transmission shaft and the auxiliary cleaning component.

[0014] Preferably, a step hole is provided at the bottom of the diamond-shaped supporting guard net, the T-shaped sleeve block is sleeved in the step hole, and the diamond-shaped supporting guard net and the T-shaped sleeve block are installed and fixed with screws, so as to facilitate subsequent installation and disassembly.

[0015] The auxiliary cleaning component is composed of a U-shaped plate and a cleaning brush strip connected to the other side surface of the U-shaped plate. One side of the U-shaped plate is fixedly connected to the surface of the transmission shaft. The number of the cleaning brush strips is not less than two and they are linearly arranged on the other side of the U-shaped plate. The end of the cleaning brush strip away from the U-shaped plate passes through the inner wall of the diamond support guard net and intermittently contacts the filter net. The auxiliary cleaning component, the transmission shaft, and the rotating support component are used in combination, and then the subsequent pressure applied to the inside of the filter device is linked to perform passive rotation, so as to contact and clean the inner wall of the diamond support guard net and the inner wall of the filter net.

[0016] Compared with the prior art, the utility model has the following beneficial effects:

[0017] 1. The utility model can further filter the effluent after the reactor sedimentation in situ. It is flexible, easy to install and disassemble, saves floor space, and does not make any changes to the reactor itself.

[0018] 2. The filter device of the utility model is arranged inside the reactor. After the filter screen inside the filter device is filtered, the microorganisms on the surface continue to be retained in the reactor with the sludge settling effect and the flushing of backwashing, thereby improving the biological retention effect of the reactor. At the same time, backwashing at a certain frequency will further improve the service life and separation effect of the filter screen. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a front view schematic diagram of the structure of the utility model;

[0020] Figure 2 It is an enlarged schematic diagram of the structural filtering device of the utility model;

[0021] Figure 3 This is a front view schematic diagram of the diamond-shaped support net of the utility model structure;

[0022] Figure 4 It is an enlarged schematic diagram of the structural filter screen of the utility model;

[0023] Figure 5 It is a front view schematic diagram of the structural filtering device of the utility model;

[0024] Figure 6 It is a bottom view schematic diagram of the auxiliary cleaning component of the structure of the utility model;

[0025] Figure 7 It is an enlarged schematic diagram of the auxiliary cleaning component of the structure of the utility model;

[0026] Figure 8 It is a cross-sectional schematic diagram of the auxiliary cleaning component of the structure of the utility model;

[0027] Fig. 9 It is a rear view schematic diagram of the structural rotating support component of the utility model.

[0028] In the figure: 1. pipeline pump; 2. first connecting valve pipe; 3. blower; 4. second connecting valve pipe; 5. filtering device; 51. diamond-shaped supporting net; 52. filter screen; 6. external thread interface; 7. float switch; 8. rotating support component; 81. T-type sleeve; 82. supporting bearing; 83. sealing ring; 9. transmission shaft; 10. auxiliary cleaning component; 101. U-shaped plate; 102. cleaning brush strip; 11. reactor. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0030] Embodiment 1

[0031] See also Figure 1-5 A solid-liquid separation system for backwashing of an anaerobic ammonium oxidation reactor, comprising a reactor 11 and a solid-liquid separation system, wherein an overflow port is arranged at the top of the reactor 11, a water inlet is arranged at the bottom of the reactor 11, a solid-liquid separation zone is arranged inside the top of the reactor 11, and the solid-liquid separation system comprises a filter component, a control pump component, and a backwash component;

[0032] The filter assembly is mounted on the upper part of the solid-liquid separation zone of the reactor 11 and below the liquid surface;

[0033] The control pump assembly is a pipeline pump 1 equipped with a float switch 7. The float switch 7 is placed on the liquid surface of the liquid inside the reactor 11. The float switch 7 sets a maximum liquid level and a minimum liquid level for the liquid level inside the reactor 11. The maximum liquid level does not exceed the overflow port of the reactor, and the minimum liquid level is not lower than the filter device 5, so as to avoid the pipeline pump 1 pumping water while the filter screen 52 is exposed to the air for idling and exhausting, thereby reducing the use damage of the pipeline pump 1.

[0034] The backwash component is composed of a filter device 5 and an external thread interface 6 that are sealed and connected. The filter device 5 is composed of a diamond-shaped support mesh 51 and a filter screen 52 that covers and wraps the surface of the diamond-shaped support mesh 51. The top of the diamond-shaped support mesh 51 is connected to the other end of the external thread interface 6. The diamond-shaped support mesh 51 is preferably made of stainless steel, which can support the annular filter screen 52 to prevent deformation during subsequent use. The filter screen 52 is a 20-80 mesh filter structure, and the surface of the filter screen 52 is coated with an anti-corrosion coating to increase the service life. The filter device 5 is cylindrical as a whole, which can increase the contact area between the filter screen and the solid-liquid mixture and improve the filtering effect. The overall filter device is placed horizontally to minimize the water pressure difference at various locations on the filter screen;

[0035] One end of the external thread interface 6 is connected to the second connecting valve pipe 4, one end of the second connecting valve pipe 4 extends to the outside of the reactor 11 and is connected to the blower 3, the pipeline structure of the second connecting valve pipe 4 located outside the pipeline pump 1 is connected to the first connecting valve pipe 2, and one end of the first connecting valve pipe 2 is connected to the input end of the pipeline pump 1;

[0036] The tube body of the first connecting valve tube 2 and the tube body of the second connecting valve tube 4 are both made of hard tubes, and the valve on the tube body of the first connecting valve tube 2 and the valve on the tube body of the second connecting valve tube 4 are both solenoid valves, such as PVC tubes. Then the first connecting valve tube 2 and the second connecting valve tube 4 form a pipeline system in the overall device, which has the effect of resisting pressure and deformation under high water pressure and air pressure. The use of solenoid valves can provide structural conditions for the subsequent automatic adjustment of the overall device to achieve backwashing state and filtering and drainage state.

[0037] Working principle: When in use, when the liquid level of the reactor 11 rises to the highest liquid level set by the float switch 7, the electromagnetic valve in the first connecting valve tube 2 is opened, and the electromagnetic valve in the second connecting valve tube 4 is maintained in the closed state, and then the pipeline pump 1 is started, and then discharged through the tube body of the first connecting valve tube 2, the part of the tube body of the second connecting valve tube 4, the external thread interface 6 and the filter device 5. At the same time, the filter screen 52 in the filter device 5 separates the liquid in the pipeline pump 1 from the solid and the liquid, until the liquid level of the pipeline pump 1 drops to the lowest liquid level of the float switch 7, and the pipeline pump 1 stops pumping and discharges, so that the liquid level remains within a certain range;

[0038] When the filter device 5 needs to be backwashed, the electromagnetic valve in the first connecting valve tube 2 is kept closed, the electromagnetic valve in the second connecting valve tube 4 is opened, and then the blower 3 is turned on. The blower 3 forces airflow to enter the filter device 5 through the pipe body and the external thread interface 6 of the second connecting valve tube 4, so as to achieve reverse drainage or exhaust to flush the filter screen 52 and achieve a backwashing effect.

[0039] After the backwashing component is started, the air pressure first pushes the water in the second connecting valve tube 4 to backwash the filter 52. After the water in the tube 4 is drained, the gas continued to be delivered by the blower 3 also has a certain backwashing effect. The presence or absence of exhaust gas and the amount of exhaust gas can be judged based on the water bubbles, and the blockage condition of the filter 52 can also be judged.

[0040] Embodiment 2

[0041] See also Figure 1-9 A solid-liquid separation system for backwashing of an anaerobic ammonium oxidation reactor, comprising a reactor 11 and a solid-liquid separation system, wherein an overflow port is arranged at the top of the reactor 11, a water inlet is arranged at the bottom of the reactor 11, a solid-liquid separation zone is arranged inside the top of the reactor 11, and the solid-liquid separation system comprises a filter component, a control pump component, and a backwash component;

[0042] The filter assembly is mounted on the upper part of the solid-liquid separation zone of the reactor 11 and below the liquid surface;

[0043] The control pump assembly is a pipeline pump 1 equipped with a float switch 7. The float switch 7 is placed on the liquid surface of the liquid inside the reactor 11. The float switch 7 sets a maximum liquid level and a minimum liquid level for the liquid level inside the reactor 11. The maximum liquid level does not exceed the overflow port of the reactor, and the minimum liquid level is not lower than the filter device 5, so as to avoid the pipeline pump 1 pumping water while the filter screen 52 is exposed to the air for idling and exhausting, thereby reducing the use damage of the pipeline pump 1.

[0044] The backwash component is composed of a filter device 5 and an external thread interface 6 that are sealed and connected. The filter device 5 is composed of a diamond-shaped support mesh 51 and a filter screen 52 that covers and wraps the surface of the diamond-shaped support mesh 51. The top of the diamond-shaped support mesh 51 is connected to the other end of the external thread interface 6. The diamond-shaped support mesh 51 is preferably made of stainless steel, which can support the annular filter screen 52 to prevent deformation during subsequent use. The filter screen 52 is a 20-80 mesh filter structure, and the surface of the filter screen 52 is coated with an anti-corrosion coating to increase the service life. The filter device 5 is cylindrical as a whole, which can increase the contact area between the filter screen and the solid-liquid mixture and improve the filtering effect. The overall filter device is placed horizontally to minimize the water pressure difference at various locations on the filter screen;

[0045] One end of the external thread interface 6 is connected to the second connecting valve pipe 4, one end of the second connecting valve pipe 4 extends to the outside of the reactor 11 and is connected to the blower 3, the pipeline structure of the second connecting valve pipe 4 located outside the pipeline pump 1 is connected to the first connecting valve pipe 2, and one end of the first connecting valve pipe 2 is connected to the input end of the pipeline pump 1;

[0046] The tube body of the first connecting valve tube 2 and the tube body of the second connecting valve tube 4 are both made of hard tubes, and the valve on the tube body of the first connecting valve tube 2 and the valve on the tube body of the second connecting valve tube 4 are both solenoid valves, such as PVC tubes, and then the first connecting valve tube 2 and the second connecting valve tube 4 form a pipeline system in the overall device, which has the effect of resisting pressure and deformation under high water pressure and air pressure, and the use of solenoid valves can provide structural conditions for the subsequent automatic adjustment of the overall device to achieve backwashing state and filtering and drainage state;

[0047] A rotating support component 8, a transmission shaft 9, and an auxiliary cleaning component 10 are mounted on the inner side of the middle part of the diamond-shaped support guard net 51. One side of the auxiliary cleaning component 10 is fixedly connected to the surface of the transmission shaft 9. The bottom end of the transmission shaft 9 is mounted on the inner side of the rotating support component 8. The rotating support component 8 includes a T-shaped sleeve block 81, a support bearing 82, and a sealing ring 83. The support bearing 82 and the sealing ring 83 are all mounted on the inner side of the middle part of the T-shaped sleeve block 81. The inner ring structure of the support bearing 82 and the middle inner side of the sealing ring 83 are all mounted on the surface of the bottom end of the transmission shaft 9. The rotating support component 8 provides support for the rotation of the transmission shaft 9 and the auxiliary cleaning component 10. A step hole is provided at the bottom of the diamond-shaped support guard net 51. The T-shaped sleeve block 81 is mounted in the step hole and screws are used to install and fix the diamond-shaped support guard net 51 and the T-shaped sleeve block 81, which is convenient for subsequent installation and disassembly.

[0048] The auxiliary cleaning component 10 is composed of a U-shaped plate 101 and a cleaning brush strip 102 connected to the other side surface of the U-shaped plate 101. One side of the U-shaped plate 101 is fixedly connected to the surface of the transmission shaft 9. The number of the cleaning brush strips 102 is not less than two and they are linearly arranged on the other side of the U-shaped plate 101. The end of the cleaning brush strip 102 away from the U-shaped plate 101 passes through the inner wall of the diamond-shaped supporting protective net 51 and intermittently contacts the filter screen 52. The auxiliary cleaning component 10, the transmission shaft 9, and the rotating support component 8 are used in combination, and then the subsequent pressure applied to the inside of the filter device 5 is linked to passive rotation, so as to contact and clean the inner wall of the diamond-shaped supporting protective net 51 and the inner wall of the filter screen 52.

[0049] Working principle: When in use, when the liquid level of the reactor 11 rises to the highest liquid level set by the float switch 7, the electromagnetic valve in the first connecting valve tube 2 is opened, and the electromagnetic valve in the second connecting valve tube 4 is maintained in the closed state, and then the pipeline pump 1 is started, and then discharged through the tube body of the first connecting valve tube 2, the part of the tube body of the second connecting valve tube 4, the external thread interface 6 and the filter device 5. At the same time, the filter screen 52 in the filter device 5 separates the liquid in the pipeline pump 1 from the solid and the liquid, until the liquid level of the pipeline pump 1 drops to the lowest liquid level of the float switch 7, and the pipeline pump 1 stops pumping and discharges, so that the liquid level remains within a certain range;

[0050] When the filter device 5 needs to be backwashed, the electromagnetic valve in the first connecting valve tube 2 is kept closed, the electromagnetic valve in the second connecting valve tube 4 is opened, and then the blower 3 is turned on. The blower 3 forces airflow to enter the filter device 5 through the pipe body and the external thread interface 6 of the second connecting valve tube 4, so as to achieve reverse drainage or exhaust to flush the filter screen 52 and achieve a backwashing effect.

[0051] After the backwashing assembly is started, the air pressure first pushes the water in the second connecting valve tube 4 to backwash the filter 52. After the water in the tube 4 is drained, the air that the blower 3 continues to deliver also has a certain backwashing effect. Whether there is any discharged gas is determined by the water bubbles.

[0052] After the backwashing liquid or gas is transported to the interior of the diamond-shaped support mesh 51, the auxiliary cleaning component 10 is pressed and passively rotated under the support of the transmission shaft 9 and the rotating support component 8, and then a plurality of cleaning strips 102 are used to contact the inner wall of the diamond-shaped support mesh 51 and the inner wall of the filter mesh 52 in turn for active cleaning, thereby optimizing the backwashing effect.

[0053] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. At the same time, in the drawings of the present utility model, the fill pattern is only for distinguishing the layers, without any other limitation.

[0054] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A solid-liquid separation system for backwashing an anaerobic ammonium oxidation reactor, comprising a reactor (11) and a solid-liquid separation system, wherein an overflow port is provided at the top of the reactor (11) and a water inlet is provided at the bottom of the reactor (11), characterized in that: A solid-liquid separation zone is provided on the inner side of the top of the reactor (11), and the solid-liquid separation system comprises a filtering component, a control pump component, and a backwashing component; The filter assembly is mounted on the upper part of the solid-liquid separation zone of the reactor (11) and below the liquid surface; The control pump assembly is a pipeline pump (1) equipped with a float switch (7), and the float switch (7) is placed on the liquid surface of the liquid inside the reactor (11); The backwashing assembly is composed of a filter device (5) and an external thread interface (6) which are sealed and connected. One end of the external thread interface (6) is connected to a second connecting valve pipe (4). One end of the second connecting valve pipe (4) extends to the outside of the reactor (11) and is connected to a blower (3). The second connecting valve pipe (4) is located in a pipeline structure outside the pipeline pump (1) and is connected to a first connecting valve pipe (2). One end of the first connecting valve pipe (2) is connected to an input end of the pipeline pump (1).

2. A solid-liquid separation system for backwashing of an anaerobic ammonium oxidation reactor according to claim 1, characterized in that: The filtering device (5) is composed of a diamond-shaped supporting net (51) and a filter net (52) covering and wrapping the surface of the diamond-shaped supporting net (51), and the top of the diamond-shaped supporting net (51) is connected to the other end of the external thread interface (6).

3. A solid-liquid separation system for backwashing of an anaerobic ammonium oxidation reactor according to claim 2, characterized in that: The filter screen (52) is a 20-80 mesh filter screen structure, and the surface of the filter screen (52) is coated with an anti-corrosion coating.

4. A solid-liquid separation system for backwashing of an anaerobic ammonium oxidation reactor according to claim 1, characterized in that: The float switch (7) sets a maximum liquid level and a minimum liquid level for the liquid level in the reactor (11), and the maximum liquid level does not exceed the overflow port of the reactor, and the minimum liquid level does not fall below the filtering device (5).

5. The solid-liquid separation system for backwashing of an anaerobic ammonium oxidation reactor according to claim 1, characterized in that: The tube body of the first connecting valve tube (2) and the tube body of the second connecting valve tube (4) are both made of hard tubes, and the valve on the tube body of the first connecting valve tube (2) and the valve on the tube body of the second connecting valve tube (4) are both solenoid valves.

6. A solid-liquid separation system for backwashing of an anaerobic ammonium oxidation reactor according to claim 2, characterized in that: A rotating support component (8), a transmission shaft (9), and an auxiliary cleaning component (10) are sleeved on the inner side of the middle part of the diamond-shaped supporting guard net (51); one side of the auxiliary cleaning component (10) is fixedly connected to the surface of the transmission shaft (9); and the bottom end of the transmission shaft (9) is sleeved on the inner side of the rotating support component (8).

7. A solid-liquid separation system for backwashing of an anaerobic ammonium oxidation reactor according to claim 6, characterized in that: The rotating support component (8) comprises a T-shaped sleeve (81), a support bearing (82), and a sealing ring (83); the support bearing (82) and the sealing ring (83) are both sleeved on the inner side of the middle part of the T-shaped sleeve (81); the inner ring structure of the support bearing (82) and the inner side of the middle part of the sealing ring (83) are both sleeved on the surface of the bottom end of the transmission shaft (9).

8. A solid-liquid separation system for backwashing of an anaerobic ammonium oxidation reactor according to claim 7, characterized in that: A step hole is provided at the bottom of the rhombus-shaped supporting guard net (51), and the T-shaped sleeve block (81) is sleeved in the step hole. The rhombus-shaped supporting guard net (51) and the T-shaped sleeve block (81) are installed and fixed by screws.

9. A solid-liquid separation system for backwashing of an anaerobic ammonium oxidation reactor according to claim 6, characterized in that: The auxiliary cleaning component (10) is composed of a U-shaped plate (101) and a cleaning brush strip (102) connected to the surface of the other side of the U-shaped plate (101); one side of the U-shaped plate (101) is fixedly connected to the surface of the transmission shaft (9); the number of the cleaning brush strips (102) is not less than two and they are linearly arranged on the other side of the U-shaped plate (101); one end of the cleaning brush strip (102) away from the U-shaped plate (101) penetrates the inner wall of the intermittent contact filter screen (52) of the diamond-shaped supporting guard screen (51).

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