Adsorption device for treating lead-containing wastewater

Abstract

The utility model discloses an adsorption device for treating lead-containing wastewater, which relates to the technical field of wastewater treatment and comprises a base, a biological treatment box is welded on the outer wall of the top of the base, a box body is welded on the outer wall of the top of the biological treatment box, the box body is matched with the biological treatment box, and a partition plate is arranged on the inner wall of the box body. The partition plate divides the inner wall of the box body into a filter cavity and a precipitation cavity, and a first filter tank, a second filter tank and a third filter tank are slidably mounted on the inner wall of the filter cavity. According to the utility model, firstly, large-particle impurities in the wastewater are removed through multi-stage filtration, and then precipitants such as lime, sodium hydroxide and sodium sulfide are added into the wastewater through a precipitation and flocculation method, so that the precipitants are combined with lead in the wastewater to generate precipitates to remove the lead in the wastewater; and finally, carrying out biological treatment on the lead-containing wastewater through sulfate reducing bacteria, iron-oxidizing bacteria and other biological bacteria, and removing lead in the wastewater as much as possible through combination of precipitation and biological treatment so as to prevent the lead in the wastewater from polluting the environment.

Description

Technical Field

[0001] This utility model relates to the field of wastewater treatment technology, and in particular to an adsorption device for treating lead-containing wastewater. Background Technology

[0002] Lead is an essential raw material in various industries, and is widely used in industries such as storage batteries, paint, printing, and pigments. However, lead is also a widely distributed and accumulative environmental pollutant. If lead-containing wastewater is discharged in large quantities directly, it will cause serious pollution to soil and water bodies. Therefore, lead-containing wastewater needs to be treated by adsorption devices before discharge to remove lead and other pollutants from the wastewater.

[0003] However, existing lead-containing wastewater adsorption devices have certain shortcomings.

[0004] First, existing adsorption devices have relatively simple treatment methods for lead-containing wastewater, mainly using one of the following methods: physical precipitation, chemical precipitation, and microbial adsorption. Their focus is on how to remove lead from the wastewater, while neglecting other solid pollutants in the wastewater. There is no primary treatment structure for lead-containing wastewater, which means that other impurities in the wastewater will affect the subsequent sedimentation and adsorption of lead. Therefore, we propose an adsorption device for treating lead-containing wastewater.

[0005] Secondly, existing adsorption devices leave a large amount of sludge inside after treatment, which is difficult to clean and inconvenient to use. Utility Model Content

[0006] The purpose of this application is to provide an adsorption device for treating lead-containing wastewater to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, this application provides the following technical solution: an adsorption device for treating lead-containing wastewater, comprising a base, a biological treatment tank welded to the top outer wall of the base, a box body welded to the top outer wall of the biological treatment tank, the box body being adapted to the biological treatment tank, a partition provided on the inner wall of the box body dividing the inner wall of the box body into a filtration chamber and a sedimentation chamber, a first filter tank, a second filter tank, and a third filter tank slidably installed on the inner wall of the filtration chamber, the first filter tank, the second filter tank, and the third filter tank being arranged sequentially from top to bottom, the aperture of the first filter tank being larger than the aperture of the second filter tank, the aperture of the second filter tank being larger than the aperture of the third filter tank, and the apertures of the first filter tank, the second filter tank, and the third filter tank decreasing sequentially, a collection tank being slidably inserted into the bottom of the inner wall of the sedimentation chamber, and a barrier net adapted to the bottom of the collection tank being provided, the barrier net being adapted to the collection tank.

[0008] Preferably, the bottom of the third filter tank is provided with a conveying trough, the conveying trough is in contact with the inner wall of the filter chamber, the conveying trough is provided with a conveying pipe that penetrates the partition, the outer wall of the conveying pipe is provided with a water pump adapted to it, the conveying trough is square, and the top outer wall of the conveying trough is provided with a sealing strip adapted to it.

[0009] Preferably, a water inlet trough is provided at one end of the top outer wall of the tank, the water inlet trough leads into the filter chamber, a connecting pipe leading into the biological treatment tank is provided at the middle position of the bottom outer wall of the sedimentation chamber, and a water collection slope is provided around the bottom inner wall of the sedimentation chamber, the water collection slope being adapted to the connecting pipe.

[0010] Preferably, an outlet pipe is provided on one outer wall of the biological treatment tank, and the outlet pipe leads into the biological treatment tank. A purification mesh box is provided at the bottom of the inner wall of the biological treatment tank near the outlet pipe, and the outlet pipe leads into the purification mesh box. The purification mesh box is filled with activated carbon. An ultrasonic generator is installed on the bottom inner wall of the biological treatment tank, and the ultrasonic generator is equipped with an ultrasonic transducer adapted to it.

[0011] Preferably, the top inner wall of the biological treatment tank is welded with cleaning troughs that are evenly distributed, and the bottom outer wall of the cleaning troughs is provided with high-pressure nozzles that are evenly distributed. The cleaning troughs are connected by water supply pipes. A water tank is provided at one end of the top outer wall of the base. The water tank contains cleaning water. A cleaning pipe is provided at the bottom of the outer wall of the water tank on the side closer to the biological treatment tank. The end of the cleaning pipe is connected to the cleaning trough. A sewage pipe is provided at the bottom of the outer wall of the biological treatment tank on the side away from the water tank.

[0012] Preferably, a mixing shaft is rotatably mounted on the inner wall of the top of the sedimentation chamber, and mixing rollers distributed at equal intervals are welded to the outer wall of the mixing shaft. An electric motor is bolted to the outer wall of the top of the chamber, and the output shaft of the electric motor is connected to the mixing shaft.

[0013] Preferably, the top outer wall of the biological treatment tank, the top outer wall of the sedimentation chamber, and the top outer wall of the water tank are all provided with filling ports, the filling ports are provided with matching covers, and the outer wall of the water tank is provided with a liquid level window.

[0014] Preferably, a sealing door is provided on both sides of the outer wall of the box, and the sealing door is adapted to the filter chamber and the sedimentation chamber respectively. A control handle is provided on the top of the outer wall of the sealing door, and sealing gaskets are provided on the inner wall and the surrounding outer walls of the sealing door, and the sealing gaskets are adapted to the sealing door.

[0015] In summary, the technical effects and advantages of this utility model are as follows:

[0016] 1. In this utility model, wastewater is filtered sequentially through a first filter tank, a second filter tank, and a third filter tank to remove large solid particles as much as possible. After being treated by the filtration chamber, the wastewater is fed into a sedimentation chamber where flocculants are added for flocculation and sedimentation. The solid impurities after sedimentation are collected and blocked by a collection tank, separating the impurities from the wastewater. The wastewater is then purified again. After flocculation and sedimentation, the wastewater is fed into a biological treatment tank through a connecting pipe for biological treatment. Compared with traditional lead-containing wastewater adsorption devices, this method first removes large particles of lead-containing wastewater through multi-stage filtration, then uses sedimentation and flocculation by adding precipitants such as lime, sodium hydroxide, and sodium sulfide to the wastewater to react with the lead in the wastewater and remove the lead. Finally, lead-containing wastewater is treated biologically by sulfate-reducing bacteria, iron-oxidizing bacteria, and other biological bacteria. By combining sedimentation and biological treatment, lead in the wastewater is removed as much as possible, preventing lead pollution of the environment.

[0017] 2. In this utility model, after the wastewater is biologically treated, the wastewater is discharged through the outlet pipe. At the same time, the purification net cage filters the wastewater to prevent the sludge generated after the biological treatment of various pollutants in the wastewater from being discharged through the outlet pipe.

[0018] 3. In this utility model, after the wastewater is biologically treated, the upper layer of clean wastewater is discharged, while the lower layer of wastewater containing sludge is intercepted. At this time, the sewage is discharged through the sewage pipe, and at the same time, the cleaning pipe inputs water from the water tank into the cleaning tank, and then sprays it through the high-pressure nozzle to rinse the bottom inner wall of the biological treatment tank, removing the sludge attached to the bottom of the biological treatment tank, thereby cleaning the biological treatment tank, making the operation more convenient. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application 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 some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the main body's external structure in an embodiment of this application;

[0021] Figure 2 This is a schematic diagram of the cleaning tank structure in an embodiment of this application;

[0022] Figure 3 This is a schematic diagram of the cross-sectional structure of the box in the embodiment of this application;

[0023] Figure 4 This is a schematic cross-sectional view of the biological treatment box in an embodiment of this application.

[0024] In the diagram: 1. Base; 2. Biological treatment tank; 3. Tank body; 4. Partition; 5. Filter chamber; 6. Sedimentation chamber; 7. First filter tank; 8. Second filter tank; 9. Third filter tank; 10. Collection tank; 11. Conveying tank; 12. Water pump; 13. Inlet tank; 14. Connecting pipe; 15. Water collection slope; 16. Outlet pipe; 17. Purification mesh box; 18. Cleaning tank; 19. High-pressure nozzle; 20. Water tank; 21. Cleaning pipe; 22. Mixing shaft; 23. Mixing roller; 24. Motor; 25. Sealing door; 26. Sealing gasket. Detailed Implementation

[0025] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings. 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.

[0026] Example: Reference Figure 1-4 An adsorption device for treating lead-containing wastewater, as shown, includes a base 1. A biological treatment tank 2 is welded to the top outer wall of the base 1. A box body 3 is welded to the top outer wall of the biological treatment tank 2. The box body 3 is adapted to the biological treatment tank 2. A partition 4 is provided on the inner wall of the box body 3, dividing the inner wall of the box body 3 into a filtration chamber 5 and a sedimentation chamber 6. A first filter tank 7, a second filter tank 8, and a third filter tank 9 are slidably installed on the inner wall of the filtration chamber 5. The first filter tank 7, the second filter tank 8, and the third filter tank 9 are arranged sequentially from top to bottom. The pore size of the first filter tank 7 is larger than that of the second filter tank 8, the pore size of the second filter tank 8 is larger than that of the third filter tank 9, and the pore sizes of the first filter tank 7, the second filter tank 8, and the third filter tank 9 decrease sequentially. The sedimentation chamber 6 contains... A collection trough 10 is slidably inserted into the bottom of the wall. A barrier net adapted to the bottom of the collection trough 10 is provided. The barrier net is adapted to the collection trough 10. A water inlet trough 13 is provided at one end of the top outer wall of the tank body 3. The water inlet trough 13 leads into the filter chamber 5. A connecting pipe 14 leading into the biological treatment tank 2 is provided in the middle of the bottom outer wall of the sedimentation chamber 6. A water collection slope 15 is provided around the bottom inner wall of the sedimentation chamber 6. The water collection slope 15 is adapted to the connecting pipe 14. A sealing door 25 is provided on both sides of the outer wall of the tank body 3. The sealing door 25 is adapted to the filter chamber 5 and the sedimentation chamber 6 respectively. A control handle is provided on the top of the outer wall of the sealing door 25. A sealing gasket 26 is provided on the inner wall and the surrounding outer walls of the sealing door 25. The sealing gasket 26 is adapted to the sealing door 25.

[0027] With the above structure: During operation, wastewater enters the filter chamber 5 through the inlet tank 13. The wastewater is filtered sequentially through the first filter tank 7, the second filter tank 8, and the third filter tank 9. As the pore size of the first filter tank 7, the second filter tank 8, and the third filter tank 9 decreases sequentially, the wastewater undergoes multi-stage filtration to remove solid impurities, removing as many large particles as possible. After being treated in the filter chamber 5, the wastewater is fed into the sedimentation chamber 6, where flocculant is added for flocculation and sedimentation. The settled solid impurities are collected and blocked by the collection tank 10, separating the impurities from the wastewater. The wastewater is then further treated. After purification and flocculation sedimentation, the wastewater is fed into the biological treatment tank 2 through connecting pipe 14 for biological treatment. Compared with traditional lead-containing wastewater adsorption devices, this method first removes large particulate impurities from the lead-containing wastewater through multi-stage filtration, then adds precipitants such as lime, sodium hydroxide, and sodium sulfide to the wastewater through sedimentation and flocculation, causing them to aggregate with the lead in the wastewater to form precipitates and remove the lead from the wastewater. Finally, the wastewater is further treated by biological bacteria such as sulfate-reducing bacteria and iron-oxidizing bacteria. By combining sedimentation and biological treatment, the lead in the wastewater is removed as much as possible, preventing lead pollution of the environment.

[0028] like Figure 3 As shown, a conveying trough 11 is provided at the bottom of the third filter tank 9. The conveying trough 11 is in close contact with the inner wall of the filter chamber 5. The conveying trough 11 is provided with a conveying pipe that penetrates the partition 4. A water pump 12 adapted to it is provided on the outer wall of the conveying pipe. The conveying trough 11 is square. Sealing strips adapted to it are provided on all four sides of the top outer wall of the conveying trough 11. After the wastewater is filtered by the first filter tank 7, the second filter tank 8 and the third filter tank 9, the large particulate impurities are basically removed. At this time, the wastewater falls into the conveying trough 11 and is fed into the sedimentation chamber 6 through the conveying pipe for sedimentation. The conveying trough 11 is in close contact with the filter chamber 5 to prevent the wastewater from contaminating the filter chamber 5.

[0029] like Figure 4As shown, an outlet pipe 16 is installed on one outer wall of the biological treatment tank 2, which leads into the biological treatment tank 2. A purification screen box 17 is installed at the bottom of the inner wall of the biological treatment tank 2 near the outlet pipe 16, and the outlet pipe 16 leads into the purification screen box 17. The purification screen box 17 is filled with activated carbon. An ultrasonic generator is installed on the bottom inner wall of the biological treatment tank 2, and the ultrasonic generator is equipped with a matching ultrasonic transducer. After biological treatment, the wastewater is discharged through the outlet pipe 16. At the same time, the purification screen box 17 filters the wastewater to prevent the sludge generated after biological treatment from various pollutants in the wastewater from being discharged through the outlet pipe 16. Since the sludge after biological treatment settles at the bottom of the biological treatment tank 2 and the inside of the biological treatment tank 2 remains still, the sludge will not float around with the water flow when draining. Therefore, the purification screen box 17 does not need to be replaced frequently. After long-term use, it is only necessary to introduce clean water and then use the ultrasonic generator to vibrate the clean water at a certain frequency to clean the purification screen box 17.

[0030] like Figure 2 As shown, the top inner wall of the biological treatment tank 2 is welded with cleaning tanks 18 distributed at equal intervals. The bottom outer wall of the cleaning tanks 18 is equipped with high-pressure nozzles 19 distributed at equal intervals. The cleaning tanks 18 are connected by water pipes. A water tank 20 is installed at one end of the top outer wall of the base 1. The water tank 20 contains cleaning water. A cleaning pipe 21 is installed at the bottom of the outer wall of the water tank 20 near the biological treatment tank 2. The end of the cleaning pipe 21 is connected to the cleaning tank 18. A sewage pipe is installed at the bottom of the outer wall of the biological treatment tank 2 away from the water tank 20. After the wastewater is biologically treated, the upper layer of clean wastewater is discharged, and the lower layer of wastewater containing sludge is intercepted. At this time, the sewage is discharged through the sewage pipe. At the same time, the cleaning pipe 21 inputs water from the water tank 20 into the cleaning tanks 18, and then sprays it out through the high-pressure nozzles 19 to rinse the bottom inner wall of the biological treatment tank 2, removing the sludge attached to the bottom of the biological treatment tank 2, thereby cleaning the biological treatment tank 2 and making the operation more convenient.

[0031] like Figure 3 As shown, a mixing shaft 22 is rotatably installed on the inner wall of the top of the sedimentation chamber 6. Mixing rollers 23 are welded at equal intervals on the outer wall of the mixing shaft 22. A motor 24 is bolted to the outer wall of the top of the box body 3. The output shaft of the motor 24 is connected to the mixing shaft 22. When the wastewater undergoes sedimentation and flocculation, the motor 24 drives the mixing shaft 22 to rotate and drive the mixing rollers 23 to mix and stir the wastewater, so that the precipitant and wastewater can be fully mixed.

[0032] like Figure 1 As shown, the top outer wall of the biological treatment tank 2, the top outer wall of the sedimentation chamber 6, and the top outer wall of the water tank 20 are all provided with filling ports. The filling ports are equipped with matching covers. The outer wall of the water tank 20 is provided with a liquid level window. The filling ports facilitate the addition of materials, and the liquid level window facilitates the observation of the remaining water in the water tank 20, so as to facilitate timely addition.

[0033] The working principle of this practical application is as follows:

[0034] During operation, wastewater enters the filter chamber 5 through the inlet tank 13. The wastewater is then filtered sequentially through the first filter tank 7, the second filter tank 8, and the third filter tank 9. As the pore sizes of the first filter tank 7, the second filter tank 8, and the third filter tank 9 decrease sequentially, the wastewater undergoes multi-stage filtration to remove solid impurities, minimizing the removal of large particles. After treatment in the filter chamber 5, the wastewater is fed into the sedimentation chamber 6, where flocculant is added for flocculation and sedimentation. The settled solid impurities are collected and blocked by the collection tank 10, separating the impurities from the wastewater for further purification. After flocculation and sedimentation, the wastewater is fed into the biological treatment tank 2 through the connecting pipe 14 for biological treatment. Compared with traditional lead-containing wastewater adsorption devices, the wastewater first removes large particulate impurities through multi-stage filtration, then adds precipitants such as lime, sodium hydroxide, and sodium sulfide to the wastewater through sedimentation and flocculation, so that the lead in the wastewater can be precipitated and removed. Finally, the wastewater is treated by biological bacteria such as sulfate-reducing bacteria and iron-oxidizing bacteria. By combining sedimentation and biological treatment, the lead in the wastewater can be removed as much as possible to prevent lead pollution of the environment.

[0035] After the wastewater is filtered through the first filter tank 7, the second filter tank 8, and the third filter tank 9, the large particulate impurities are basically removed. At this time, the wastewater falls into the conveying tank 11 and is fed into the sedimentation chamber 6 through the conveying pipe for sedimentation. The conveying tank 11 is tightly fitted with the filter chamber 5 to prevent the wastewater from contaminating the filter chamber 5. When the wastewater is undergoing sedimentation and flocculation, the motor 24 drives the mixing shaft 22 to rotate and drive the mixing roller 23 to mix and stir the wastewater, so that the precipitant and the wastewater can be fully mixed.

[0036] After biological treatment, the wastewater is discharged through the outlet pipe 16. At the same time, the purification net box 17 filters the wastewater to prevent the sludge generated after biological treatment from various pollutants in the wastewater from being discharged through the outlet pipe 16. Since the sludge after biological treatment settles at the bottom of the biological treatment tank 2 and the inside of the biological treatment tank 2 remains still, the sludge will not float around with the water flow when draining. Therefore, the purification net box 17 does not need to be replaced frequently. After long-term use, it is only necessary to pass clean water through it and then use an ultrasonic generator to make the clean water vibrate at a certain frequency to clean the purification net box 17.

[0037] After biological treatment, the upper layer of clean wastewater is discharged, while the lower layer of wastewater containing sludge is retained. At this time, the wastewater is discharged through the sewage pipe, while the cleaning pipe 21 inputs water from the water tank 20 into the cleaning tank 18, and then sprays it through the high-pressure nozzle 19 to rinse the bottom inner wall of the biological treatment tank 2, removing the sludge attached to the bottom of the biological treatment tank 2, thereby cleaning the biological treatment tank 2, making the operation more convenient.

[0038] Finally, it should be noted that the above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Although the present utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. An adsorption device for treating lead-containing wastewater, comprising a base (1), characterized in that: A biological treatment box (2) is welded to the top outer wall of the base (1), and a box body (3) is welded to the top outer wall of the biological treatment box (2). The box body (3) is adapted to the biological treatment box (2). A partition (4) is provided on the inner wall of the box body (3). The partition (4) divides the inner wall of the box body (3) into a filtration chamber (5) and a sedimentation chamber (6). A first filter tank (7), a second filter tank (8), and a third filter tank (9) are slidably installed on the inner wall of the filtration chamber (5). The first filter tank (7), the second filter tank (8), and the third filter tank (9) are... The first filter tank (7) and the second filter tank (8) are arranged sequentially from top to bottom. The aperture of the first filter tank (7) is larger than that of the second filter tank (8), and the aperture of the second filter tank (8) is larger than that of the third filter tank (9). The apertures of the first filter tank (7), the second filter tank (8), and the third filter tank (9) decrease sequentially. A collection tank (10) is slidably inserted into the bottom of the inner wall of the sedimentation chamber (6). A barrier net adapted to the bottom of the collection tank (10) is provided. The barrier net is adapted to the collection tank (10).

2. The adsorption device for treating lead-containing wastewater according to claim 1, characterized in that: The bottom of the third filter tank (9) is provided with a conveying tank (11), which is in contact with the inner wall of the filter chamber (5). The conveying tank (11) is provided with a conveying pipe that passes through the partition (4). A water pump (12) adapted to it is provided on the outer wall of the conveying pipe. The conveying tank (11) is square, and a sealing strip adapted to it is provided on all four sides of the top outer wall of the conveying tank (11).

3. The adsorption device for treating lead-containing wastewater according to claim 1, characterized in that: The top outer wall of the box (3) is provided with a water inlet trough (13), which leads into the filter chamber (5). The bottom outer wall of the sedimentation chamber (6) is provided with a connecting pipe (14) leading into the biological treatment box (2). The bottom inner wall of the sedimentation chamber (6) is provided with a water collection slope (15) around its perimeter, which is adapted to the connecting pipe (14).

4. The adsorption device for treating lead-containing wastewater according to claim 1, characterized in that: A water outlet pipe (16) is provided on one side of the outer wall of the biological treatment tank (2), and the water outlet pipe (16) leads into the biological treatment tank (2). A purification net box (17) is provided at the bottom of the inner wall of the biological treatment tank (2) near the water outlet pipe (16), and the water outlet pipe (16) leads into the purification net box (17). The purification net box (17) is filled with activated carbon. An ultrasonic generator is installed on the bottom inner wall of the biological treatment tank (2), and the ultrasonic generator is equipped with an ultrasonic transducer that is compatible with it.

5. The adsorption device for treating lead-containing wastewater according to claim 1, characterized in that: The biological treatment tank (2) has cleaning tanks (18) welded to the inner wall of the top, and high-pressure nozzles (19) are arranged at equal intervals on the outer wall of the bottom of the cleaning tank (18). The cleaning tanks (18) are connected by water pipes. A water tank (20) is provided at one end of the outer wall of the top of the base (1). The water tank (20) contains cleaning water. A cleaning pipe (21) is provided at the bottom of the outer wall of the water tank (20) near the biological treatment tank (2). The end of the cleaning pipe (21) is connected to the cleaning tank (18). A sewage pipe is provided at the bottom of the outer wall of the biological treatment tank (2) away from the water tank (20).

6. The adsorption device for treating lead-containing wastewater according to claim 1, characterized in that: A mixing shaft (22) is rotatably mounted on the inner wall of the top of the sedimentation chamber (6). Mixing rollers (23) are welded at equal intervals on the outer wall of the mixing shaft (22). An electric motor (24) is bolted to the outer wall of the top of the box body (3). The output shaft of the electric motor (24) is connected to the mixing shaft (22).

7. The adsorption device for treating lead-containing wastewater according to claim 5, characterized in that: The top outer wall of the biological treatment tank (2), the top outer wall of the sedimentation chamber (6), and the top outer wall of the water tank (20) are all provided with filling ports. The filling ports are provided with matching cover plates, and the outer wall of the water tank (20) is provided with a liquid level window.

8. The adsorption device for treating lead-containing wastewater according to claim 1, characterized in that: The outer walls of the box (3) are provided with sealing doors (25) on both sides. The sealing doors (25) are adapted to the filter chamber (5) and the sedimentation chamber (6) respectively. The top of the outer wall of the sealing door (25) is provided with a control handle. The inner wall of the sealing door (25) and the surrounding outer walls are provided with sealing gaskets (26). The sealing gaskets (26) are adapted to the sealing door (25).

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