A seawater centralized raw water treatment system for fish farming

Abstract

The present application relates to the technical field of mariculture, and particularly relates to a seawater centralized raw water treatment system for fish culture; the seawater centralized raw water treatment system comprises a first filter container, a second filter container and a sand filter tank; the position height of the third water inlet pipe > the position height of the second water inlet pipe > the position height of the first water inlet pipe. The turbidity detection module is arranged at the water inlet and water outlet end, and the controller can calculate the turbidity difference before and after filtration in real time. When the difference exceeds the threshold value, the system determines that the filter cover is blocked, and the lifting mechanism is automatically started to replace or clean. The sand filter tank adopts a unique three-layer filter material design of "upper ceramic particles-middle sand-lower ceramic particles". The upper ceramic particles intercept large particle suspended solids, the middle sand performs fine filtration, and the lower ceramic particles not only play a supporting role, but also can attach a large number of beneficial microorganisms, biodegrade dissolved organic matter, and significantly improve the water quality of the outlet water.

Description

Technical Field

[0001] This invention relates to the field of marine aquaculture technology, and in particular to a centralized seawater intake and raw water treatment system for aquaculture. Background Technology

[0002] In conventional marine aquaculture, the quality of the raw water directly determines the survival rate and growth rate of farmed organisms. Directly extracted natural seawater contains a large amount of suspended solids, silt, harmful organisms, and pathogens, and therefore must be effectively treated.

[0003] In existing technologies, such as the multi-stage purification system disclosed in patent CN208250072U, the maintenance of each filtration unit (especially the cleaning and replacement of the filter screen) is highly dependent on manual labor. It cannot adaptively adjust to changes in the upstream water quality, resulting in unstable treatment efficiency and high operation and maintenance costs. Furthermore, when a treatment unit malfunctions or requires maintenance, the entire system must be shut down, severely impacting the continuity of aquaculture production. Therefore, there is an urgent need for a highly automated raw water treatment system with online monitoring and self-maintenance capabilities, capable of uninterrupted operation. Summary of the Invention

[0004] The purpose of this invention is to provide a centralized seawater intake and raw water treatment system for aquaculture, which solves the problems in the prior art where the filtration unit cannot perform adaptive automatic maintenance according to water quality and the lack of a backup mechanism in the system leads to poor production continuity.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: This invention provides a centralized seawater intake and raw water treatment system for aquaculture, comprising a first filter container connected to a water intake and delivery pipe via a first water inlet pipe, a second filter container connected to the first filter container via a second water inlet pipe, and a sand filter tank connected to the second filter container via a third water inlet pipe. Wherein, the position height of the third water inlet pipe is greater than the position height of the second water inlet pipe, which is greater than the position height of the first water inlet pipe; A first inlet turbidity detection module is installed on the first inlet pipe, and a first outlet turbidity detection module is installed on the third inlet pipe; The first filter container and the second filter container are respectively provided with water quality filtration and interception mechanisms that are easy to disassemble and replace. The water quality filtration and interception mechanism includes a filter mechanism respectively provided in the first filter container and the second filter container, and a lifting adjustment mechanism for adjusting the filter mechanism to detach from the filter container. The first inlet turbidity detection module, the second outlet turbidity detection module, and the lifting adjustment mechanism are each electrically connected to a controller. The controller adjusts the operation of the lifting adjustment mechanism based on the difference detected by the first inlet turbidity detection module and the first outlet turbidity detection module.

[0006] Furthermore, it also includes a first backup filter, a second backup filter, and a backup sand filter tank as backups; wherein, the first backup filter has the same structure as the first filter container; and the second backup filter has the same structure as the second filter container. The first backup filter is connected to an inlet pipe via a first inlet pipe; the outlet of the first backup filter is connected to the second backup filter via a second inlet pipe, and the second backup filter is connected to the backup sand filter tank via a third inlet pipe; wherein, the position height of the third inlet pipe is greater than the position height of the second inlet pipe, which is greater than the position height of the first inlet pipe.

[0007] Furthermore, the water inlet pipe is connected to the first filter container through a first water inlet branch pipe, and a first valve is installed on the first water inlet branch pipe; the water inlet pipe is connected to the first backup filter through a second water inlet branch pipe, and a second valve is installed on the second water inlet branch pipe; The sand filter tank and the spare sand filter tank are respectively provided with a first ceramsite layer, a sand layer and a second ceramsite layer from top to bottom; the bottom of the sand filter tank and the spare sand filter tank are respectively connected to an outlet pipe through a first outlet branch pipe and a second outlet branch pipe; a third valve is provided on the first outlet branch pipe and a fourth valve is provided on the second outlet branch pipe.

[0008] Furthermore, the first valve, the second valve, the third valve, and the fourth valve are all electrically controlled valves and are each electrically connected to a controller.

[0009] Furthermore, a second inlet turbidity detection module is installed on the first inlet pipe of the first backup filter; a second outlet turbidity detection module is installed on the third inlet pipe of the backup sand filter tank; the second inlet turbidity detection module and the second outlet turbidity detection module are electrically connected to a controller.

[0010] Furthermore, the filtration mechanism includes an assembly frame disposed in the filter container and a separation filter cover detachably disposed in the assembly frame. The assembly frame includes a limiting base, an arc-shaped filter screen coaxially connected to the limiting base, and a connecting ring disposed on the top of the arc-shaped filter screen. A reserved cavity for accommodating the separation filter cover is formed inside the assembly frame; wherein, the separation filter cover is a cylindrical mesh tube. The top of the assembly frame inside the second filter container is connected to a first hollow connecting pipe, and the upper end of the first hollow connecting pipe is connected to the lifting adjustment mechanism. The top of the assembly frame inside the first filter container is connected to a second hollow connecting pipe, and the upper end of the second hollow connecting pipe is connected to the lifting adjustment mechanism.

[0011] Furthermore, the lifting and adjusting mechanism includes a support disposed above the first filter container and the second filter container, a base disposed on the support, a top plate disposed directly above the base, a guide rod and a lead screw connecting the top plate and the base, a lead screw slide disposed on the lead screw and the guide rod respectively via a lead screw nut seat and a sliding sleeve, and a lead screw motor disposed on the top of the top plate for driving the lead screw and the lead screw slide thereon; Position sensors for detecting the lead screw slide are respectively installed on the top plate and the base; the position sensors and the lead screw motor are electrically connected to a controller; The first hollow connecting pipe and the second hollow connecting pipe are symmetrically arranged on the lead screw slide.

[0012] Furthermore, the bottom of the support is provided with a support leg, and a reserved groove is provided on the support to facilitate the passage of the first hollow connecting pipe and the second hollow connecting pipe.

[0013] Furthermore, a first cleaning nozzle for spraying water into the assembly frame is provided at the lower end of the first hollow connecting pipe; and a second cleaning nozzle for spraying water into the other assembly frame is provided at the lower end of the second hollow connecting pipe. A first cleaning water supply pipe connecting the delivery pump and the first cleaning nozzle is embedded in the first hollow connecting pipe; a second cleaning water supply pipe connecting the delivery pump and the second cleaning nozzle is embedded in the second hollow connecting pipe. The inlet of the delivery pump is connected to the outlet of the sand filter tank or the spare sand filter tank via a pipeline. The delivery pump is electrically connected to a controller.

[0014] Furthermore, both the bottom of the first filter container and the bottom of the second filter container are equipped with drain pipes and valves.

[0015] Compared with the prior art, the beneficial technical effects of the present invention are as follows: (1) Intelligent adaptive maintenance: By setting up turbidity detection modules at the inlet and outlet, the controller can calculate the turbidity difference before and after filtration in real time. When the difference exceeds the threshold, the system determines that the filter cover is blocked and automatically starts the lifting mechanism to replace or clean it, realizing on-demand maintenance and avoiding the waste of resources of "replacing when it expires" and the lag of manual inspection.

[0016] (2) Ensure production continuity: By setting up parallel backup filters and backup sand filter tanks and configuring electrically controlled valves, when the main channel equipment needs maintenance, it can be switched to the backup channel instantly, realizing online maintenance and uninterrupted water supply of the system, which greatly improves the safety of aquaculture production.

[0017] (3) High-efficiency composite filtration: The sand filter tank adopts a unique three-layer filter media design of "top ceramic particles - middle sand - bottom ceramic particles". The top layer of ceramic particles intercepts large suspended particles, the middle layer of sand performs fine filtration, and the bottom layer of ceramic particles, in addition to playing a supporting role, can also attach a large number of beneficial microorganisms in its porous structure, which can biodegrade dissolved organic matter and significantly improve the quality of the effluent.

[0018] (4) Reduced operation and maintenance costs: The combined use of the lifting and adjusting mechanism and the automatic cleaning device makes it possible to clean and replace the filter cover without manual entry into the tank, saving time and effort, and reducing the risk of high-risk operations and labor costs. Attached Figure Description

[0019] The present invention will be further described below with reference to the accompanying drawings. Figure 1 This is a schematic diagram of the main structure of the centralized seawater intake and raw water treatment system for aquaculture of the present invention; Figure 2 This is a top view schematic diagram of the main body of the centralized seawater intake and raw water treatment system for aquaculture of the present invention; Figure 3 This is a schematic diagram of the adjustment mechanism of the filter components in the filter container; Figure 4 for Figure 3 Schematic diagram of the lifting and adjusting structure; Figure 5 This is a schematic diagram of the filter mechanism. Figure 6 This is a schematic diagram of the disassembled structure of the filtration mechanism.

[0020] Explanation of reference numerals in the attached drawings: 1. First filter container; 1a. First backup filter; 1b. First inlet pipe; 2. Second filter container; 2a. Second backup filter; 2b. Second inlet pipe; 3. Sand filter tank; 3a. Backup sand filter tank; 3b. Third inlet pipe; 31. First ceramsite layer; 32. Sand layer; 33. Second ceramsite layer; 4. Inlet pipe; 41. First inlet branch pipe; 411. First valve; 42. Second inlet branch pipe; 421. Second valve; 5. Outlet pipe; 51. First outlet branch pipe; 511. Third valve; 52. Second outlet branch pipe; 521. Fourth valve; 6. Support; 61. Support leg; 62. Reserved groove; 7. Lifting and adjusting mechanism 71. Top plate; 72. Base; 73. Guide rod; 74. Lead screw; 75. Lead screw slide; 76. Lead screw motor; 8. Filtering mechanism; 81. Assembly frame; 811. Limiting chassis; 812. Arc-shaped filter screen; 813. Connecting ring; 82. Separation filter cover; 9. Conveying pump; 91. First cleaning water supply pipe; 911. First hollow connecting pipe; 912. First cleaning nozzle; 92. Second cleaning water supply pipe; 921. Second hollow connecting pipe; 922. Second cleaning nozzle; 101. First inlet turbidity detection module; 102. First outlet turbidity detection module; 103. Second inlet turbidity detection module; 104. Second outlet turbidity detection module. Detailed Implementation

[0021] Example 1 refer to Figure 1 and Figure 2 This embodiment provides a centralized seawater intake and raw water treatment system for aquaculture, including a main treatment pathway and a backup treatment pathway.

[0022] Main treatment pathway: Seawater enters through inlet pipe 4, first flowing through the first inlet branch pipe 41 into the first filter container 1. The first filter container 1 has a drain pipe and valve at its bottom. After preliminary filtration in the first filter container 1, the seawater flows by gravity into the second filter container 2 through the second inlet pipe 2b. The effluent from the second filter container 2 flows by gravity into the top of the sand filter tank 3 through the third inlet pipe 3b. The bottom of the sand filter tank 3 is connected to the outlet pipe 5 through the first outlet branch pipe 51, supplying water to the aquaculture pond.

[0023] Backup processing pathway: includes a first backup filter 1a, a second backup filter 2a, and a backup sand filter tank 3a. The first backup filter 1a is connected to the inlet pipe 4 via a second inlet branch pipe 42; the second backup filter 2a is connected between the first backup filter 1a and the backup sand filter tank 3a; the bottom of the backup sand filter tank 3a is connected in parallel to the outlet pipe 5 via a second outlet branch pipe 52. Each branch pipe is equipped with an electrically controlled valve (411, 421, 511, 521), and all electrically controlled valves are electrically connected to the controller.

[0024] refer to Figure 3 The first filter container 1 and the second filter container 2 have the same internal structure, both equipped with a liftable filter mechanism 8. The filter mechanism 8 includes an assembly frame 81 and a cylindrical separation filter cover 82. The assembly frame 81 consists of a bottom limiting base 811, an arc-shaped filter screen 812 on the side wall, and a connecting ring 813 at the top. The separation filter cover 82 is detachably installed inside the assembly frame 81. A first hollow connecting pipe 911 is connected to the top of the assembly frame 81 inside the second filter container 2, and a second hollow connecting pipe 921 is connected to the top of the assembly frame 81 inside the first filter container 1. The upper ends of both connecting pipes are connected to a lifting adjustment mechanism 7.

[0025] refer to Figure 4 The lifting and adjusting mechanism 7 is mounted on a support 6 located above the filter container. It includes a base 72, a top plate 71, a guide rod 73, a lead screw 74, a lead screw slide 75, and a lead screw motor 76. The lead screw slide 75 can slide up and down along the guide rod 73 under the drive of the lead screw motor 76. The top ends of the first hollow connecting pipe 911 and the second hollow connecting pipe 921 are symmetrically fixed to the lead screw slide 75. Position sensors for detecting the position of the lead screw slide 75 are provided on the top plate 71 and the base 72.

[0026] The system is equipped with monitoring modules at key locations: a first inlet turbidity detection module 101 is installed on the inlet pipe 1b of the first filter container 1; a first outlet turbidity detection module 102 is installed on the inlet pipe 3b of the sand filter tank 3. Similarly, a second inlet turbidity detection module 103 and a second outlet turbidity detection module 104 are also installed on the backup passage. All detection modules, the lead screw motor 76, and the position sensor are electrically connected to the controller.

[0027] Working principle Water intake and gravity flow: Seawater enters the system through inlet pipe 4. Thanks to the height design of "position of the third inlet pipe 3b > position of the second inlet pipe 2b > position of the first inlet pipe 1b", the water will automatically and sequentially flow through the first filter container 1, the second filter container 2 and the sand filter tank 3 under the action of gravity, allowing time for impurities to settle through hydraulic retention.

[0028] Gradient filtration: Water first enters the first filter container 1. The cylindrical separation filter 82 intercepts most of the larger particles of silt, algae, and harmful organisms. The effluent then enters the second filter container 2, where the separation filter 82 inside performs a second round of fine filtration. The separation filter 82 in the first filter container 1 has a larger pore size than the separation filter 82 in the second filter container 2. Finally, the water enters the sand filter tank 3. Inside the tank, the water passes from top to bottom through a first layer of ceramic aggregate 31 with larger pores, a dense sand layer 32, and a second layer of ceramic aggregate 33 that combines support and biological purification functions, completing the final fine filtration and biodegradation.

[0029] Intelligent monitoring and automatic maintenance: Data acquisition: The first influent turbidity detection module 101 and the first effluent turbidity detection module 102 monitor the turbidity of the water before and after filtration in real time and send the data to the controller.

[0030] Status judgment: The controller has a preset standard threshold for turbidity removal rate. When the calculated (influent turbidity - effluent turbidity) / influent turbidity is lower than this threshold, it is determined that the filter mechanism 8 is clogged and the filtration efficiency decreases.

[0031] Automatic response: The controller then issues a command to activate the lifting and adjusting mechanism 7. The lead screw motor 76 drives the lead screw 74 to rotate, causing the lead screw slide 75 to move upward. The lead screw slide 75, through the first hollow connecting pipe 911 and the second hollow connecting pipe 921 fixed thereto, vertically lifts the entire filtration mechanism 8 inside the first filter container 1 and the second filter container 2 to the maintenance area at the top of the filter container.

[0032] Online maintenance: Operators can easily disassemble and replace or clean the filter cover 82. In a more advanced automated configuration, when the filter cover is lifted, the system can automatically start the delivery pump 9, which delivers the clean water treated by the sand filter tank 3 through the first cleaning water supply pipe 91 and the second cleaning water supply pipe 92 to the first cleaning nozzle 912 and the second cleaning nozzle 922, respectively, to perform reverse spraying and washing of the clogged filter cover 82, achieving manual cleaning without the need for manual cleaning.

[0033] Uninterrupted operation guarantee: When the main treatment path (such as the first filter container 1) requires maintenance, the operator can remotely close the first valve 411 on the first inlet branch pipe 41 and simultaneously open the second valve 421 on the second inlet branch pipe 42 via the controller. At this time, the source water will automatically switch to the backup path consisting of the first backup filter 1a, the second backup filter 2a, and the backup sand filter tank 3a. The entire switching process is smooth and the water supply is uninterrupted, ensuring the continuity of aquaculture production.

[0034] Example 2 This embodiment refines the control logic based on Embodiment 1. The controller has a pre-set "differential pressure-time" composite judgment program. When the difference between the influent turbidity and the effluent turbidity increases sharply within a short period (e.g., within 30 minutes), or when the difference exceeds the threshold for more than 2 hours, the controller determines that the filter is clogged. Conversely, if the influent turbidity is already extremely high, causing a large difference in a short time, but the effluent turbidity remains within the acceptable range, the controller will not initiate the maintenance program but will instead issue an influent water quality warning signal. This judgment logic effectively avoids system malfunctions caused by sudden and drastic fluctuations in source water quality due to typhoons, heavy rains, etc.

[0035] Example 3 This embodiment optimizes the filter media of the sand filter tank. The first ceramsite layer 31 has ceramsite particles with a diameter of 5-8 mm and a height of 0.6 m; the sand layer 32 has quartz sand particles with a diameter of 1-2 mm and a height of 0.8 m; the second ceramsite layer 33 has ceramsite particles with a diameter of 10-15 mm and a height of 0.3 m, and a support layer is also provided at its lower part. This gradation ensures a balance between filtration accuracy and dirt-holding capacity, while providing a large attachment surface area for beneficial microorganisms such as nitrifying bacteria.

[0036] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A centralized seawater intake and treatment system for aquaculture, characterized in that: It includes a first filter container (1) connected to a water intake and delivery pipe via a first water inlet pipe (1b), a second filter container (2) connected to the first filter container (1) via a second water inlet pipe (2b), and a sand filter tank (3) connected to the second filter container (2) via a third water inlet pipe (3b). Wherein, the position height of the third water inlet pipe (3b) is greater than the position height of the second water inlet pipe (2b) and the position height of the first water inlet pipe (1b); A first inlet turbidity detection module (101) is provided on the first inlet pipe (1b), and a first outlet turbidity detection module (102) is provided on the third inlet pipe (3b). The first filter container (1) and the second filter container (2) are respectively provided with water quality filtration interception mechanisms that are easy to disassemble and replace. The water quality filtration interception mechanism includes a filter mechanism (8) respectively provided in the first filter container (1) and the second filter container (2), and a lifting adjustment mechanism (7) for adjusting the filter mechanism (8) to detach from the filter container. The first inlet turbidity detection module (101), the second outlet turbidity detection module (102), and the lifting adjustment mechanism (7) are electrically connected to a controller. The controller adjusts the operation of the lifting adjustment mechanism (7) based on the difference detected by the first inlet turbidity detection module (101) and the first outlet turbidity detection module (102).

2. The centralized seawater intake and raw water treatment system for aquaculture according to claim 1, characterized in that: It also includes a first backup filter (1a), a second backup filter (2a), and a backup sand filter tank (3a) as backups; wherein the first backup filter (1a) has the same structure as the first filter container (1); and the second backup filter (2a) has the same structure as the second filter container (2). The first backup filter (1a) is connected to the inlet pipe (4) through the first inlet pipe (1b); the outlet of the first backup filter (1a) is connected to the second backup filter (2a) through the second inlet pipe (2b), and the second backup filter (2a) is connected to the backup sand filter tank (3a) through the third inlet pipe (3b); wherein, the position height of the third inlet pipe (3b) is greater than the position height of the second inlet pipe (2b) and the position height of the first inlet pipe (1b).

3. The centralized seawater intake and raw water treatment system for aquaculture according to claim 2, characterized in that: The water inlet pipe (4) is connected to the first filter container (1) through the first water inlet branch pipe (41), and a first valve (411) is provided on the first water inlet branch pipe (41); the water inlet pipe (4) is connected to the first spare filter (1a) through the second water inlet branch pipe (42), and a second valve (421) is provided on the second water inlet branch pipe (42). Among them, a first ceramsite layer (31), a sand layer (32), and a second ceramsite layer (33) are respectively arranged from top to bottom in the sand filter tank (3) and the spare sand filter tank (3a); the bottom of the sand filter tank (3) and the spare sand filter tank (3a) are respectively connected to the outlet pipe (5) through the first outlet branch pipe (51) and the second outlet branch pipe (52); a third valve (511) is provided on the first outlet branch pipe (51), and a fourth valve (521) is provided on the second outlet branch pipe (52).

4. The centralized seawater intake and raw water treatment system for aquaculture according to claim 3, characterized in that: The first valve (411), the second valve (421), the third valve (511), and the fourth valve (521) are electrically controlled valves and are electrically connected to a controller.

5. The centralized seawater intake and raw water treatment system for aquaculture according to claim 3, characterized in that: A second inlet turbidity detection module (103) is provided on the first inlet pipe (1b) of the first backup filter (1a); a second outlet turbidity detection module (104) is provided on the third inlet pipe (3b) of the backup sand filter tank (3a); the second inlet turbidity detection module (103) and the second outlet turbidity detection module (104) are electrically connected to a controller.

6. The centralized seawater intake and raw water treatment system for aquaculture according to any one of claims 1-5, characterized in that: The filtration mechanism (8) includes an assembly frame (81) disposed in the filter container and a separation filter cover (82) detachably disposed in the assembly frame (81). The assembly frame (81) includes a limiting base (811), an arc-shaped filter screen (812) coaxially connected to the limiting base (811), and a connecting ring (813) disposed on the top of the arc-shaped filter screen (812). A reserved cavity for receiving the separation filter cover (82) is formed inside the assembly frame (81); wherein, the separation filter cover (82) is a cylindrical mesh tube. The top of the assembly frame (81) inside the second filter container (2) is connected to a first hollow connecting pipe (911), and the upper end of the first hollow connecting pipe (911) is connected to the lifting adjustment mechanism (7). The top of the assembly frame (81) inside the first filter container (1) is connected to a second hollow connecting pipe (921), and the upper end of the second hollow connecting pipe (921) is connected to the lifting adjustment mechanism (7).

7. The centralized seawater intake and raw water treatment system for aquaculture according to claim 6, characterized in that: The lifting adjustment mechanism (7) includes a support (6) disposed above the first filter container (1) and the second filter container (2), a base (72) disposed on the support (6), a top plate (71) disposed directly above the base (72), a guide rod (73) and a lead screw (74) connecting the top plate (7) and the base (72), a lead screw slide (75) disposed on the lead screw (74) and the guide rod (73) respectively through a lead screw nut seat and a sliding sleeve, and a lead screw motor (76) disposed on the top of the top plate (71) for driving the lead screw (74) and the lead screw slide (75) thereon; Position sensors for detecting the lead screw slide (75) are respectively provided on the top plate (71) and the base (72); the position sensors and the lead screw motor (76) are electrically connected to a controller; The first hollow connecting pipe (911) and the second hollow connecting pipe (921) are symmetrically arranged on the lead screw slide (75).

8. The centralized seawater intake and raw water treatment system for aquaculture according to claim 7, characterized in that: The bottom of the support (6) is provided with a support leg (61), and a reserved groove (62) is provided on the support (6) to facilitate the passage of the first hollow connecting pipe (911) and the second hollow connecting pipe (921).

9. The centralized seawater intake and raw water treatment system for aquaculture according to claim 6, characterized in that: A first cleaning nozzle (912) for spraying water into the assembly frame (81) is provided at the lower end of the first hollow connecting pipe (911); a second cleaning nozzle (922) for spraying water into the other assembly frame (81) is provided at the lower end of the second hollow connecting pipe (921). A first cleaning water supply pipe (91) connecting the delivery pump (9) and the first cleaning nozzle (912) is embedded in the first hollow connecting pipe (911); a second cleaning water supply pipe (92) connecting the delivery pump (9) and the second cleaning nozzle (922) is embedded in the second hollow connecting pipe (921). The inlet of the delivery pump (9) is connected to the outlet of the sand filter tank (3) or the spare sand filter tank (3) via a pipeline. The delivery pump (9) is electrically connected to a controller.

10. The centralized seawater intake and raw water treatment system for aquaculture according to claim 1, characterized in that: Both the bottom of the first filter container (1) and the bottom of the second filter container (2) are equipped with drain pipes and valves.

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