An aerobic mixed liquor nitrification and deoxygenation treatment device

Abstract

This utility model discloses an aerobic mixed liquor nitrification and deoxygenation treatment device, including a first nitrification tank. A nitrite-containing bacteria storage tank is located at the top of the first nitrification tank. An inlet pipe is located at the top of one side of the first nitrification tank, and one side of the inlet pipe extends into the interior of the first nitrification tank and is equipped with a sludge-water separation chamber. Through the cooperation of the inlet pipe, sludge discharge pipe, screen, and sludge-water separation chamber, this utility model can separate the sludge mixed in with the mixed liquor during its inflow, while also facilitating the return of the sludge to the treatment tank. Then, through the cooperation of a second discharge pipe, a third pump, a pump installation chamber, a distribution plate, a distribution pipe, a heat dissipation chamber, and a fan, the mixed liquor can be continuously circulated and cooled during the nitrification reaction, thereby maintaining the mixed liquor at 20-30°C to preserve the activity of nitrite-containing bacteria and nitrifying bacteria in the mixed liquor and ensure reaction efficiency.

Description

Technical Field

[0001] This utility model relates to the field of wastewater treatment technology, specifically to an aerobic mixed liquor nitrification and deoxygenation treatment device. Background Technology

[0002] Aerobic mixed liquor is the mixed liquor in the activated sludge process, containing microorganisms, organic matter, and dissolved oxygen. To remove NH3 / NH4 from the mixed liquor... + Then it is necessary to use the nitrification deoxygenation method to treat it.

[0003] A nitrification liquid deoxygenation recirculation wastewater treatment system, with existing patent publication number "CN218345281U", includes an anoxic tank, an aerobic tank, and a deoxygenation tank. An inlet is located at the top of one side wall of the deoxygenation tank, and an outlet is located at the bottom of the opposite side wall. The inlet is connected to the aerobic tank via a nitrification liquid lift-back pipe, and the outlet is connected to the anoxic tank via a nitrification liquid circulation pipe. The inlet and outlet side walls of the deoxygenation tank are alternately equipped with inclined baffles to cause the nitrification liquid to flow back and forth. Using this nitrification liquid deoxygenation recirculation wastewater treatment system, the nitrification liquid flows through the deoxygenation tank in a baffled manner, extending the deoxygenation treatment time of the nitrification liquid. Simultaneously, the inclined baffles also disperse the nitrification liquid, thereby improving the deoxygenation treatment effect and ultimately enhancing the denitrification nitrogen and phosphorus removal efficiency.

[0004] However, the nitrification process of wastewater generates a lot of heat, which causes the temperature of the solution to rise. If the temperature is too high, it may affect the reaction rate. The system cannot maintain the reaction temperature well, thus affecting the nitrification process of the device. Utility Model Content

[0005] The purpose of this invention is to provide an aerobic mixed liquor nitrification and deoxygenation treatment device to solve the existing problems mentioned in the background art.

[0006] To achieve the above objectives, this utility model provides the following technical solution: an aerobic mixed liquor nitrification and deoxygenation treatment device, comprising a first nitrification tank, characterized in that: a nitrite-oxidizing bacteria liquid storage tank is provided at the top of the first nitrification tank, an inlet pipe is provided at the top of one side of the first nitrification tank, one side of the inlet pipe extends into the interior of the first nitrification tank and is provided with a mud-water separation chamber, a sludge discharge pipe is provided on one side of the mud-water separation chamber, one side of the sludge discharge pipe extends out of the exterior of the first nitrification tank, a screen is provided on one side inside the mud-water separation chamber, a main pipe is provided at the bottom of the mud-water separation chamber, and a multi-component liquid discharge pipe is provided on the outside of the main pipe;

[0007] A first liquid-passing pipe is provided at the bottom of one side of the first nitrification tank. A first liquid-drawing pump is provided between the inlet and outlet of the first liquid-passing pipe. A second nitrification tank is provided on one side of the first liquid-passing pipe. A nitrifying bacteria liquid storage tank is provided at the top of the second nitrification tank. Spiral liquid-guiding pipes are provided at the bottom of the interior of both the second and first nitrification tanks. A pump installation chamber is provided at the top of one side of the interior of both the first and second nitrification tanks. A third liquid-drawing pump is provided inside the pump installation chamber. A second liquid-draining pipe is provided at the output end of the third liquid-draining pump. One side of each of the two sets of second liquid-draining pipes extends into the interior of the first and second nitrification tanks, respectively.

[0008] A heat dissipation chamber is provided between the two sets of pump installation chambers. A liquid distribution plate is provided at the input end of the third liquid pump. Multiple liquid distribution pipes are evenly distributed on one side of the liquid distribution plate. A fluid collection plate is provided between the sides of the multiple sets of liquid distribution pipes. A first installation pipe is provided at the bottom of the fluid collection plate. A first drain pipe is provided on one side of the first installation pipe. Fans are symmetrically arranged on both sides of the top of the heat dissipation chamber.

[0009] A second liquid inlet pipe is provided at the bottom of one side of the second nitrification tank. A second liquid pump is provided between the outlet and inlet of the second liquid inlet pipe. A denitrification tank is provided on one side of the second liquid inlet pipe. A first solenoid valve is provided at the bottom of one side of the denitrification tank. A first liquid outlet pipe is provided on one side of the first solenoid valve. A denitrifying bacteria liquid storage tank is provided at the top of the denitrification tank. A second solenoid valve is provided at the bottom of the denitrifying bacteria liquid storage tank, the nitrifying bacteria liquid storage tank, and the nitrite bacteria liquid storage tank. A second liquid outlet pipe is provided at the bottom of the second solenoid valve. A pressure relief assembly is provided at the top of one side of the denitrification tank.

[0010] Preferably, the pressure relief assembly includes an exhaust pipe, a vent plate, a spring, a baffle ring, a sealing plug, and a second mounting pipe. The exhaust pipe is located at the top of one side of the denitrification tank. A vent plate is provided on one side of the exhaust pipe, and a second mounting pipe is provided in the middle of one side of the vent plate. A spring is provided inside the second mounting pipe, and a sealing plug is provided on one side of the spring. A baffle ring is provided on the side of the exhaust pipe away from the vent plate. During the denitrification process, if the internal pressure of the denitrification tank is too high, nitrogen can be automatically discharged to reduce the pressure. At the same time, it can also ensure an oxygen-deficient environment inside the denitrification tank, so that the denitrifying bacteria can treat the wastewater.

[0011] Preferably, both the first and second pumps are provided with protective chambers on their outer sides for protection.

[0012] Preferably, the second drain pipe is installed at an angle downwards and is located at the top of the spiral guide pipe, so that the second drain pipe can be aligned with the spiral guide pipe to drain water.

[0013] Preferably, the heat dissipation chamber is provided with a mounting cover on one side, and both one end of the mounting cover and the top of the heat dissipation chamber are provided with multiple sets of heat dissipation holes to facilitate gas circulation.

[0014] Preferably, a connecting plate is provided between the first nitrification tank and the second nitrification tank, and a support leg is provided at the bottom of the heat dissipation chamber, and the support leg is connected to the connecting plate to support the heat dissipation chamber.

[0015] Preferably, a sliding rod is provided on one side of the sealing plug, and the sliding rod is located inside the second mounting tube to ensure the stability of the connection.

[0016] Preferably, the top of the first nitrification tank, the second nitrification tank, and the denitrification tank are all provided with connection holes, and multiple sets of the second solenoid valves extend into the interior of the first nitrification tank, the second nitrification tank, and the denitrification tank through the connection holes to facilitate drainage.

[0017] Compared with the prior art, the beneficial effects of this utility model are: the aerobic mixed liquor nitrification deoxygenation treatment equipment;

[0018] 1. Through the cooperation of the inlet pipe, sludge discharge pipe, screen, and sludge-water separation chamber, the sludge mixed in with the mixed liquor can be separated during the inflow process, and the sludge can be easily returned to the treatment tank. Then, through the cooperation of the second discharge pipe, the third pump, the pump installation chamber, the distribution plate, the distribution pipe, the heat dissipation chamber, and the fan, the mixed liquor can be continuously circulated and cooled during the nitrification reaction, thereby maintaining the mixed liquor at 20-30℃ to maintain the activity of nitrite-oxidizing bacteria and nitrifying bacteria in the mixed liquor and ensure the efficiency of the reaction. In this continuous circulation process, the water flow directly impacts the spiral guide pipe for guidance. During the pumping and return process, the water flow is forced to generate centrifugal force, thereby allowing the bacteria to be fully mixed with the sewage mixed liquor and improving the reaction efficiency.

[0019] 2. With the cooperation of the exhaust pipe, vent plate, spring, baffle ring, sealing plug and second installation pipe, if the internal pressure of the denitrification tank is too high during the denitrification process, nitrogen can be automatically discharged to reduce the air pressure. At the same time, it can also ensure the anoxic environment inside the denitrification tank, so that the denitrifying bacteria can treat the wastewater. Attached Figure Description

[0020] Figure 1 This is a perspective view of the present utility model;

[0021] Figure 2 This is a front sectional view of the present invention;

[0022] Figure 3 This is a top view of the spiral liquid guide tube of this utility model;

[0023] Figure 4This is a side sectional view of the liquid distribution plate of this utility model;

[0024] Figure 5 This is an enlarged view of the pressure relief component of this utility model.

[0025] In the diagram: 1. First nitrification tank; 2. Inlet pipe; 3. Sludge discharge pipe; 4. Screen; 5. Separator pipe; 6. Main pipe; 7. Spiral guide pipe; 8. First liquid passage pipe; 9. First liquid pump; 10. Fluid collection tray; 11. First installation pipe; 12. First drain pipe; 13. Second nitrification tank; 14. Second liquid pump; 15. Second liquid passage pipe; 16. Denitrification tank; 17. First solenoid valve; 18. First outlet pipe; 19. Pressure relief assembly; 191. Venting. 192. Pipe; 193. Ventilation plate; 194. Spring; 195. Air baffle ring; 196. Sealing plug; 197. Second installation pipe; 20. Denitrifying bacteria liquid storage tank; 21. Second drain pipe; 22. Nitrifying bacteria liquid storage tank; 23. Third pump; 24. Pump installation compartment; 25. Separating tray; 26. Separating pipe; 27. Heat dissipation compartment; 28. Fan; 29. ​​Mud-water separation compartment; 30. Nitrite bacteria liquid storage tank; 31. Second solenoid valve; 32. Second outlet pipe. Detailed Implementation

[0026] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0027] Please see Figure 1-5 The present invention provides an embodiment of an aerobic mixed liquor nitrification and deoxygenation treatment device, comprising a first nitrification tank 1, characterized in that: a nitrite bacteria liquid storage tank 30 is provided at the top of the first nitrification tank 1, an inlet pipe 2 is provided at the top of one side of the first nitrification tank 1, one side of the inlet pipe 2 extends into the interior of the first nitrification tank 1 and is provided with a mud-water separation chamber 29, a sludge discharge pipe 3 is provided on one side of the mud-water separation chamber 29, one side of the sludge discharge pipe 3 extends out of the exterior of the first nitrification tank 1, a screen 4 is provided on one side inside the mud-water separation chamber 29, a main pipe 6 is provided at the bottom of the mud-water separation chamber 29, and a multi-component liquid discharge pipe 5 is provided on the outside of the main pipe 6;

[0028] A first liquid passage pipe 8 is provided at the bottom of one side of the first nitrification tank 1. A first liquid pump 9 is provided between the inlet and outlet of the first liquid passage pipe 8. A second nitrification tank 13 is provided on one side of the first liquid passage pipe 8. A nitrifying bacteria liquid storage tank 22 is provided at the top of the second nitrification tank 13. A spiral liquid guide pipe 7 is provided at the bottom of the interior of both the second nitrification tank 13 and the first nitrification tank 1. A pump installation chamber 24 is provided at the top of one side of the interior of both the first nitrification tank 1 and the second nitrification tank 13. A third liquid pump 23 is provided inside the pump installation chamber 24. A second liquid drain pipe 21 is provided at the output end of the third liquid pump 23. One side of the two sets of second liquid drain pipes 21 extends into the interior of the first nitrification tank 1 and the second nitrification tank 13 respectively. The second liquid drain pipe 21 is installed at an angle downward and is located at the top of the spiral liquid guide pipe 7. The second liquid drain pipe 21 can be aligned with the spiral liquid guide pipe 7 to drain water.

[0029] A heat dissipation chamber 27 is provided between the two pump installation chambers 24. A connecting plate is provided between the first nitrification tank 1 and the second nitrification tank 13. The bottom of the heat dissipation chamber 27 is provided with a support leg, and the support leg is connected to the connecting plate to support the heat dissipation chamber 27. The input end of the third liquid pump 23 is provided with a liquid distribution plate 25. A multi-component liquid distribution pipe 26 is evenly distributed on one side of the liquid distribution plate 25. A fluid collection plate 10 is provided between the sides of the multi-component liquid distribution pipe 26. A first installation pipe 11 is provided at the bottom of the fluid collection plate 10. A first drain pipe 12 is provided on one side of the first installation pipe 11. Fans 28 are symmetrically arranged on both sides of the top inside the heat dissipation chamber 27.

[0030] A second liquid inlet pipe 15 is provided at the bottom of one side of the second nitrification tank 13. A second liquid pump 14 is provided between the outlet and inlet of the second liquid inlet pipe 15. A denitrification tank 16 is provided on one side of the second liquid inlet pipe 15. A first solenoid valve 17 is provided at the bottom of one side of the denitrification tank 16. A first outlet pipe 18 is provided on one side of the first solenoid valve 17. A denitrifying bacteria liquid storage tank 20 is provided at the top of the denitrification tank 16. The bottoms of the denitrifying bacteria liquid storage tank 20, the nitrifying bacteria liquid storage tank 22, and the nitrite bacteria liquid storage tank 30 are... Each part is equipped with a second solenoid valve 31. The top of the first nitrification tank 1, the second nitrification tank 13, and the denitrification tank 16 are all equipped with connection holes. Multiple sets of second solenoid valves 31 extend into the interior of the first nitrification tank 1, the second nitrification tank 13, and the denitrification tank 16 through the connection holes to facilitate liquid drainage. The bottom of the second solenoid valve 31 is equipped with a second liquid outlet pipe 32. The top of one side of the denitrification tank 16 is equipped with a pressure relief component 19. The outer sides of the first liquid pump 9 and the second liquid pump 14 are both equipped with protective chambers for protection.

[0031] The pressure relief assembly 19 includes an exhaust pipe 191, a vent plate 192, a spring 193, a baffle ring 194, a sealing plug 195, and a second mounting pipe 196. The exhaust pipe 191 is located at the top of one side of the denitrification tank 16. The vent plate 192 is provided on one side of the exhaust pipe 191. The second mounting pipe 196 is located in the middle of one side of the vent plate 192. The spring 193 is provided inside the second mounting pipe 196. The sealing plug 195 is provided on one side of the spring 193. The sliding rod is provided on one side of the sealing plug 195 and is located inside the second mounting pipe 196 to ensure the stability of the connection. The baffle ring 194 is provided on the side of the exhaust pipe 191 away from the vent plate 192. During the denitrification process, if the internal pressure of the denitrification tank 16 is too high, nitrogen can be automatically discharged to reduce the pressure. At the same time, it can also ensure the anoxic environment inside the denitrification tank 16, so that the denitrifying bacteria can treat the wastewater.

[0032] Working principle: During the treatment process, the aerobic mixed liquor is first introduced into the sludge-water separation chamber 29 through the inlet pipe 2. Then, the sludge and liquid are discharged to the screen 4. The liquid falls through the mesh of the screen 4 into the main pipe 6 and the liquid distribution pipe 5 for discharge, while the sludge slides down the screen 4 into the sludge discharge pipe 3 and flows back into the sludge tank. When the mixed liquor enters the first nitrification tank 1, the second solenoid valve 31 is activated to discharge the nitrite bacteria solution in the nitrite bacteria storage tank 30 into the first nitrification tank 1. Under aerobic conditions, ammonia nitrogen is converted into nitrite by nitrite bacteria, and heat is released at the same time, which raises the temperature of the mixed liquor. As the temperature rises, the third pump 23 is activated. The third pump 23 sequentially draws the mixture into the first drain pipe 12, the first mounting pipe 11, and the fluid collection plate 10, and then distributes it through the distribution pipe 26. At this time, the fan 28 is activated to dissipate heat from the mixture inside the distribution pipe 26. The cooled mixture then flows into the distribution plate 25 and is discharged from the second drain pipe 21 to the spiral guide pipe 7 by the third pump 23. During the discharge process, the spiral guide pipe 7 forcibly guides the water flow and generates centrifugal force, so that the nitrite bacteria can be fully mixed with the mixture.

[0033] After processing, the first pump 9 is started, drawing the mixture into the second nitrification tank 13 through the first liquid inlet pipe 8. At this time, the second solenoid valve 31 inside the second nitrification tank 13 is activated, draining the nitrifying bacteria solution from the nitrifying bacteria solution storage tank 22 into the second nitrification tank 13, further oxidizing nitrite to nitrate, while also releasing heat. This process is then repeated for heat dissipation. After processing, the second pump 14 is started, drawing the solution into the denitrification tank 16 through the second liquid inlet pipe 15, and then... The second solenoid valve 31 inside the denitrification tank 16 discharges the denitrifying bacteria liquid from the denitrifying bacteria liquid storage tank 20 into the denitrification tank 16. In an oxygen-deficient environment, nitrates are gradually reduced to nitrogen gas, while carbon dioxide and water are generated, thus completing denitrification. If the gas pressure inside the denitrification tank 16 is too high, the gas pressure will push open the sealing plug 195 and drive the spring 193 to compress it. Then, the nitrogen gas inside the denitrification tank 16 is discharged to the outside along the baffle ring 194 and the vent plate 192. After the reaction is completed, the first solenoid valve 17 is activated to discharge the liquid.

[0034] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0035] In the description of this utility model, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," "front end," "rear end," "head," "tail," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. In addition, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0036] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection or a detachable connection; a mechanical connection or an electrical connection; a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

Claims

1. An aerobic mixed liquor nitrification and deoxidation treatment apparatus comprising a first nitrification tank (1), characterized in that: The top of the first nitrification tank (1) is provided with a nitrite bacteria liquid storage tank (30). The top of one side of the first nitrification tank (1) is provided with a liquid inlet pipe (2). One side of the liquid inlet pipe (2) extends into the interior of the first nitrification tank (1) and is provided with a mud-water separation chamber (29). One side of the mud-water separation chamber (29) is provided with a mud discharge pipe (3). One side of the mud discharge pipe (3) extends out of the exterior of the first nitrification tank (1). One side of the interior of the mud-water separation chamber (29) is provided with a screen (4). The bottom of the mud-water separation chamber (29) is provided with a main pipe (6). The outside of the main pipe (6) is provided with a multi-component liquid discharge pipe (5). A first liquid-passing pipe (8) is provided at the bottom of one side of the first nitrification tank (1). A first liquid pump (9) is provided between the inlet and outlet of the first liquid-passing pipe (8). A second nitrification tank (13) is provided on one side of the first liquid-passing pipe (8). A nitrifying bacteria liquid storage tank (22) is provided at the top of the second nitrification tank (13). A spiral liquid guide pipe (7) is provided at the bottom of the interior of both the second nitrification tank (13) and the first nitrification tank (1). A pump installation chamber (24) is provided at the top of one side of the interior of both the first nitrification tank (1) and the second nitrification tank (13). A third liquid pump (23) is provided inside the pump installation chamber (24). A second drain pipe (21) is provided at the output end of the third liquid pump (23). One side of each of the two sets of second drain pipes (21) extends into the interior of the first nitrification tank (1) and the second nitrification tank (13). A heat dissipation chamber (27) is provided between the two sets of pump installation chambers (24). A liquid distribution plate (25) is provided at the input end of the third liquid pump (23). Multiple liquid distribution pipes (26) are evenly arranged on one side of the liquid distribution plate (25). A fluid collection plate (10) is provided between the sides of the multiple sets of liquid distribution pipes (26). A first installation pipe (11) is provided at the bottom of the fluid collection plate (10). A first drain pipe (12) is provided on one side of the first installation pipe (11). Fans (28) are symmetrically arranged on both sides of the top of the heat dissipation chamber (27). A second liquid inlet pipe (15) is provided at the bottom of one side of the second nitrification tank (13). A second liquid pump (14) is provided between the outlet and inlet of the second liquid inlet pipe (15). A denitrification tank (16) is provided on one side of the second liquid inlet pipe (15). A first solenoid valve (17) is provided at the bottom of one side of the denitrification tank (16). A first outlet pipe (18) is provided on one side of the first solenoid valve (17). A denitrifying bacteria liquid storage tank (20) is provided at the top of the denitrification tank (16). A second solenoid valve (31) is provided at the bottom of the denitrifying bacteria liquid storage tank (20), the nitrifying bacteria liquid storage tank (22), and the nitrite bacteria liquid storage tank (30). A second outlet pipe (32) is provided at the bottom of the second solenoid valve (31). A pressure relief assembly (19) is provided at the top of one side of the denitrification tank (16).

2. The aerobic mixed liquor nitrification and denitrification treatment apparatus according to claim 1, characterized by: The pressure relief assembly (19) includes an exhaust pipe (191), a vent plate (192), a spring (193), a baffle ring (194), a sealing plug (195), and a second mounting pipe (196). The exhaust pipe (191) is located at the top of one side of the denitrification tank (16). A vent plate (192) is provided on one side inside the exhaust pipe (191). A second mounting pipe (196) is provided in the middle of one side of the vent plate (192). A spring (193) is provided inside the second mounting pipe (196). A sealing plug (195) is provided on one side of the spring (193). A baffle ring (194) is provided on the side of the exhaust pipe (191) away from the vent plate (192).

3. The aerobic mixed liquor nitrification and deoxygenation treatment equipment according to claim 1, characterized in that: The first pump (9) and the second pump (14) are both equipped with protective chambers on their outer sides.

4. The aerobic mixed liquor nitrification and deoxygenation treatment equipment according to claim 1, characterized in that: The second drain pipe (21) is installed at an angle downwards, and the second drain pipe (21) is located at the top of the spiral guide pipe (7).

5. The aerobic mixed liquor nitrification and deoxygenation treatment equipment according to claim 1, characterized in that: The heat dissipation chamber (27) has a mounting cover on one side, and multiple sets of heat dissipation holes are provided at one end of the mounting cover and at the top of the heat dissipation chamber (27).

6. The aerobic mixed liquor nitrification and deoxygenation treatment equipment according to claim 1, characterized in that: A connecting plate is provided between the first nitrification tank (1) and the second nitrification tank (13), and a support leg is provided at the bottom of the heat dissipation chamber (27), and the support leg is connected to the connecting plate.

7. The aerobic mixed liquor nitrification and deoxygenation treatment equipment according to claim 2, characterized in that: The sealing plug (195) has a slide rod on one side, and the slide rod is located inside the second mounting tube (196).

8. The aerobic mixed liquor nitrification and deoxygenation treatment equipment according to claim 1, characterized in that: The top of the first nitrification tank (1), the second nitrification tank (13) and the denitrification tank (16) are provided with connection holes, and multiple sets of the second solenoid valves (31) extend into the interior of the first nitrification tank (1), the second nitrification tank (13) and the denitrification tank (16) respectively through the connection holes.

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