High-pH raw water treatment device

Abstract

The utility model discloses a high-pH raw water treatment device which comprises a coagulative precipitation tank, a water inlet pipe arranged at one end of the coagulative precipitation tank, a first connecting pipe arranged at the other end of the coagulative precipitation tank, an activated carbon filter tank communicated with the coagulative precipitation tank through the first connecting pipe, and a second connecting pipe group arranged on the activated carbon filter tank, the membrane filter tank is communicated with the activated carbon filter tank through a second connecting pipe group, the carbon dioxide adding mechanism is communicated with the activated carbon filter tank and the membrane filter tank, and the water outlet pipe is arranged on the membrane filter tank. Through the arrangement of the carbon dioxide adding mechanism, carbon dioxide is added into water, so that the pH value of raw water is reduced, and the residual aluminum amount of factory water is reduced.

Description

Technical Field

[0001] This utility model relates to the technical field of water treatment devices, specifically to a high pH value raw water treatment device. Background Technology

[0002] Currently, most regions rely on reservoirs for water supply. However, due to economic and social development around lakes and reservoirs, particularly aquaculture, pollutants (such as organic matter and nutrients) enter these water bodies via rivers, leading to eutrophication. Many domestic lakes and reservoirs are in a meso-eutrophic state, resulting in excessive seasonal algal blooms. Algae consume large amounts of carbon dioxide during their growth, causing a decrease in carbonate and bicarbonate levels and a significant increase in pH. Currently, water treatment plants in my country use aluminum-based coagulants. Aluminum is an amphoteric substance with a certain solubility under weakly alkaline conditions. Therefore, when algal blooms occur in water sources, causing an increase in raw water pH, the treated water may have a higher aluminum concentration.

[0003] In existing water purification processes, multiple membrane treatment processes are usually involved downstream of the flocculation device. High concentrations of aluminum ions in raw water with high pH can penetrate the membrane modules of subsequent processes, leading to membrane fouling and damage. Therefore, in order to protect the membrane modules, it is necessary to adjust the pH value of the raw water.

[0004] To address the issue of high aluminum concentration in treated water due to high raw water pH, domestic water plants currently mainly use methods such as adding acidifying coagulants, increasing the dosage of coagulants, or directly adding acid to the raw water to lower the pH. However, all of these methods have drawbacks: using acidifying coagulants and increasing the dosage of coagulants increases the treatment cost of treated water, and the residual aluminum content in the treated water is difficult to control, still posing a risk of exceeding standards. Furthermore, frequent switching of coagulants is detrimental to the stable operation of the water plant process. Adding acid to the raw water requires the construction of a new acidification system, which requires a large investment, and the strong acid is corrosive, increasing safety hazards at the water plant.

[0005] Therefore, how to provide a safer method to reduce aluminum ion concentration and the residual aluminum content in the treated water is an urgent technical problem that needs to be solved. Utility Model Content

[0006] The purpose of this invention is to propose a high-pH raw water treatment device to solve the problem of high aluminum ion concentration in the effluent water of existing water plants in the background art.

[0007] To achieve the above objectives, this utility model proposes a high-pH raw water treatment device, comprising a coagulation sedimentation tank, an inlet pipe disposed at one end of the coagulation sedimentation tank, a first connecting pipe disposed at the other end of the coagulation sedimentation tank, an activated carbon filter connected to the coagulation sedimentation tank via the first connecting pipe, a second connecting pipe assembly disposed on the activated carbon filter, a membrane filter connected to the activated carbon filter via the second connecting pipe assembly, a carbon dioxide dosing mechanism connected to the activated carbon filter and the membrane filter, and an outlet pipe disposed on the membrane filter; the carbon dioxide dosing mechanism includes a dosing component for dosing carbon dioxide to the activated carbon filter and the membrane filter, a first pH sensor disposed on the inlet pipe, and a controller connected to the first pH sensor, the controller being connected to the dosing component.

[0008] Optionally, the coagulation sedimentation tank includes a first tank body, a flocculant delivery pipe disposed in the first tank body, and a flocculant metering pump installed at one end of the flocculant delivery pipe; the first tank body is provided with a partition block, which divides the internal space of the first tank body into a mixing zone and a sedimentation zone.

[0009] Optionally, one end of the flocculant dispensing pipe and the water inlet pipe are both located in the mixing zone; the flocculant dispensing pipe is provided with 5 dispensing holes at equal intervals, and the flocculant dispensing pipe is also provided with a one-way valve.

[0010] Optionally, the orientation of the flocculant delivery pipe is perpendicular to the orientation of the inlet pipe, and the minimum distance between the installation position of the flocculant delivery pipe and the bottom surface of the first tank is equal to the minimum distance between the installation position of the inlet pipe and the bottom surface of the first tank.

[0011] Optionally, a water passage is formed between the partition block and the bottom surface of the inner cavity of the first pool body. The bottom surface of the partition block is provided with a guide surface, and an acute angle is formed between the guide surface and the bottom surface of the first pool body with the opening facing the water inlet pipe.

[0012] Optionally, a sedimentation frame is provided in the sedimentation zone, a filter screen is installed on the sedimentation frame, and a hook bolt is installed on the sedimentation frame; the distance between the first connecting pipe and the bottom surface of the first tank body is greater than the height of the sedimentation frame.

[0013] Optionally, the activated carbon filter includes a second tank body, multiple mounting platforms disposed within the second tank body, a support plate mounted on the mounting platforms, and an activated carbon layer filled on the support plate.

[0014] Optionally, each support plate has two sets of saddle clips staggered at its bottom, one set of which is used to support the dosing component.

[0015] Optionally, the support plate is provided with through holes, the diameter of which is smaller than the particle size of the activated carbon layer; an oxygen aeration pipe is installed at the bottom of the support plate via another set of saddle clamps.

[0016] Optionally, the membrane filtration tank includes a third tank body, a plurality of membrane modules mounted on a second connecting pipe assembly and located within the third tank body; and a dosing assembly mounted on the bottom surface of the inner cavity of the third tank body and connected to the membrane modules.

[0017] Optionally, the outlet pipe is located at the bottom of the third tank, and a second pH sensor connected to the controller is installed on the third tank.

[0018] Optionally, the dosing assembly includes a carbon dioxide storage tank, an outlet pipe installed on the carbon dioxide storage tank, a carbon dioxide metering pump installed on the carbon dioxide storage tank, a main dosing pipe installed at the outlet of the carbon dioxide metering pump, and two sets of carbon dioxide aeration pipes installed on the main dosing pipe, with the two sets of carbon dioxide aeration pipes located in the activated carbon filter and the membrane filter, respectively.

[0019] Compared with the prior art, this utility model provides a high pH raw water treatment device, which has the following beneficial effects:

[0020] This high-pH raw water treatment device adds carbon dioxide to the water through a carbon dioxide dosing mechanism. The carbon dioxide reacts with the water to produce carbonic acid, which ionizes into hydrogen ions in the water, thereby lowering the original pH value and reducing the residual aluminum content in the treated water. Compared with existing methods that use acidifying coagulants or strong acid neutralization, the carbon dioxide in this application is less expensive. Moreover, compared with the storage of strong acids, the storage of carbon dioxide is safer and poses less safety risks. It also reduces the use of chemical additives, thereby reducing environmental pollution and operational risks. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of this utility model.

[0022] Figure 2 This is a top view of the overall structure of this utility model.

[0023] Figure 3 This is a cross-sectional view of the second pool body of this utility model.

[0024] Figure 4 This is a structural schematic diagram of the sedimentation frame and filter screen of this utility model.

[0025] Figure 5 This is a schematic diagram of the structure of the support plate of this utility model.

[0026] The diagram shows: 1. Coagulation sedimentation tank; 11. First connecting pipe; 12. First tank body; 121. Separator block; 122. Mixing zone; 123. Sedimentation zone; 124. Water passage; 125. Guide surface; 126. Sedimentation frame; 127. Filter screen; 128. Hook bolt; 13. Flocculant dosing pipe; 131. Dosing hole; 132. One-way valve; 14. Flocculant metering pump; 2. Activated carbon filter; 20. Second connecting pipe assembly; 21. Second tank body; 22. Safety... 1. Mounting platform; 23. Support plate; 231. Through hole; 232. Oxygen aeration pipe; 24. Activated carbon layer; 3. Membrane filtration tank; 31. Third tank body; 32. Membrane module; 4. Carbon dioxide dosing mechanism; 41. Dosing component; 411. Carbon dioxide storage tank; 412. Gas outlet pipe; 413. Carbon dioxide metering pump; 414. Dosing main pipe; 415. Carbon dioxide aeration pipe; 42. First pH sensor; 44. Second pH sensor; 5. Inlet pipe; 6. Outlet pipe. Detailed Implementation

[0027] The following detailed description, in conjunction with the accompanying drawings and specific embodiments, illustrates the present invention. Numerous specific details are set forth in the description below to provide a thorough understanding of the invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0028] The high pH raw water treatment device of this application can be used for purifying water with high pH value, and can also be used in other similar application scenarios. The high pH raw water treatment device is described in detail below.

[0029] See appendix Figure 1 — Figure 5The diagram shows a preferred embodiment of a high-pH raw water treatment device according to this application. The high-pH raw water treatment device includes a coagulation sedimentation tank 1, an inlet pipe 5 at one end of the coagulation sedimentation tank 1, a first connecting pipe 11 at the other end of the coagulation sedimentation tank 1, an activated carbon filter 2 connected to the coagulation sedimentation tank 1 via the first connecting pipe 11, a second connecting pipe assembly 20 on the activated carbon filter 2, a membrane filter 3 connected to the activated carbon filter 2 via the second connecting pipe assembly 20, a carbon dioxide dosing mechanism 4 connected to the activated carbon filter 2 and the membrane filter 3, and an outlet pipe 6 on the membrane filter 3. This invention utilizes a coagulation sedimentation tank 1 to mix raw water with flocculant, causing impurities in the raw water to flocculate and settle, thus performing preliminary filtration and purification. An activated carbon filter 2 adsorbs organic matter and removes heavy metal ions such as aluminum ions, further filtration and purification, and prevents aluminum ions from affecting subsequent membrane modules. A membrane filter 3 performs fine filtration to ensure complete purification and meets factory standards. A carbon dioxide dosing mechanism 4 introduces carbon dioxide gas into the water, lowering the pH value, reducing aluminum ion content, and extending membrane lifespan.

[0030] See appendix Figure 1 and Figure 2 As shown, in this utility model, the coagulation sedimentation tank 1 includes a first tank body 12, a flocculant delivery pipe 13 disposed in the first tank body 12, and a flocculant metering pump 14 installed at one end of the flocculant delivery pipe 13; the first tank body 12 is provided with a partition block 121, which divides the internal space of the first tank body 12 into a mixing zone 122 and a sedimentation zone 123.

[0031] This invention utilizes a flocculant dispensing pipe 13 to mix flocculant with water, causing impurities in the water to flocculate and settle. A flocculant metering pump 14 is used to add a measured amount of flocculant to the water, preventing excessive flocculant addition that would increase costs, require additional processing steps and equipment, and also avoiding insufficient flocculant addition that would affect the flocculation and sedimentation effect. A partition block 121 divides the first pool 12 into a mixing zone 122 for mixing water and flocculant, and a sedimentation zone 123 for impurities after mixing. It should be noted that the other end of the flocculant metering pump 14 is connected to a flocculant storage tank.

[0032] See appendix Figure 1 and Figure 2As shown, in this utility model, one end of both the flocculant delivery pipe 13 and the water inlet pipe 5 is located within the mixing zone 122; the flocculant delivery pipe 13 is provided with delivery holes 131 at equal intervals, and the flocculant delivery pipe 13 is also provided with a one-way valve 132; the orientation of the flocculant delivery pipe 13 is perpendicular to the orientation of the water inlet pipe 5, and the minimum distance between the installation position of the flocculant delivery pipe 13 and the bottom surface of the first pool body 12 is equal to the minimum distance between the installation position of the water inlet pipe 5 and the bottom surface of the first pool body 12.

[0033] This invention places both the flocculant delivery pipe 13 and the water inlet pipe 5 within the mixing zone 122, allowing the flocculant to immediately contact and flocculate upon entering the first tank 12, thus providing a foundation for subsequent sedimentation. The delivery hole 131 discharges the flocculant into the mixing zone 122 to mix with the water. A one-way valve 132 restricts the direction of flocculant movement, preventing backflow into the flocculant metering pump 14 and protecting it. By limiting the installation heights of the flocculant delivery pipe 13 and the water inlet pipe 5, the water flowing from the water inlet pipe 5 impacts the flocculant delivery pipe 13, rapidly mixing with the flocculant, thereby increasing the sedimentation rate of impurities in the water and improving purification efficiency.

[0034] See appendix Figure 1 and Figure 2 As shown, in this utility model, a water passage 124 is formed between the partition block 121 and the bottom surface of the inner cavity of the first pool body 12. The bottom surface of the partition block 121 is provided with a guide surface 125. The guide surface 125 and the bottom surface of the first pool body 12 form an angle with the opening facing the water inlet pipe 5. The angle is an acute angle.

[0035] This invention, through the water passage 124, allows the water mixed with the flocculant to settle impurities in the sedimentation zone 123; through the guide surface 125, the flow direction of the water is guided, causing the water to flow towards the bottom of the first pool 12, while also guiding the flocculated impurities to move towards the bottom of the first pool 12, thereby improving the efficiency of flocculation and sedimentation.

[0036] See appendix Figure 1 , Figure 2 and Figure 4 As shown, in this utility model, a sedimentation frame 126 is provided in the sedimentation zone 123, a filter screen 127 is installed on the sedimentation frame 126, and a hook bolt 128 is installed on the sedimentation frame 126; the distance between the first connecting pipe 11 and the bottom surface of the first pool body 12 is greater than the height of the sedimentation frame 126.

[0037] This invention provides an installation position for the filter screen 127 through the setting of the sedimentation frame 126; the filter screen 127 is used to filter water and prevent sedimented impurities from flowing into the activated carbon filter tank 2; the hook bolt 128 makes it easy for workers to remove the sedimentation frame 126 with lifting equipment, thereby facilitating the removal and cleaning of sedimented impurities; by limiting the installation position of the first connecting pipe 11, it is ensured that only water that has passed through the filter screen 127 can enter through the first connecting pipe 11.

[0038] It should be noted that the sedimentation frame 126 has a slot on the side without the filter screen 127, which can be used to install a sealing plate to block the end of the sedimentation frame 126 facing the water passage 124, so as to prevent the sediment from shaking and entering the mixing zone 122 when the sedimentation frame 126 is removed for cleaning.

[0039] See appendix Figure 1 — Figure 3 As shown, in this utility model, the activated carbon filter 2 includes a second tank body 21, multiple mounting platforms 22 disposed in the second tank body 21, a support plate 23 mounted on the mounting platform 22, and an activated carbon layer 24 filled on the support plate 23; each support plate 23 has two sets of saddle clips staggered at its bottom, one set of saddle clips being used to support the dosing component 41.

[0040] This invention provides an installation position for the support plate 23 by setting up the mounting platform 22; supports the activated carbon layer 24 with different particle sizes by setting up multiple support plates 23; and allows the activated carbon layer 24 to adsorb water multiple times, thereby improving the purification effect of the water.

[0041] It should be noted that the two sets of saddle clamps are used to support the dosing component 41 and the oxygen aeration pipe 232, respectively.

[0042] See appendix Figure 1 — Figure 3 , Figure 5 As shown, in this utility model, the support plate 23 is provided with a through hole 231, the diameter of which is smaller than the particle size of the activated carbon layer 24; an oxygen aeration pipe 232 is installed at the bottom of the support plate 23 by another set of saddle clamps.

[0043] This invention, through the through-hole 231, ensures that water can come into contact with the activated carbon layer 24 via the support plate 23, thereby allowing the activated carbon in the activated carbon layer 24 to filter and purify the water. The oxygen aeration pipe 232 is used to dissolve oxygen into the water, increasing the oxygen content and enabling microorganisms in the water to decompose organic matter in the original water, further purifying the water. By placing the oxygen aeration pipe 232 and the carbon dioxide aeration pipe 415 at the bottom of the support plate 23, it effectively prevents the activated carbon from clogging the outlet of the aeration pipe. The three mounting platforms 22 are arranged in a stepped configuration.

[0044] It should be noted that there are three mounting platforms 22 in this application, which means there are also three support plates 23. The activated carbon layer 24 has three layers, and the aperture of the through holes 231 on the three support plates 23 gradually decreases from the bottom to the top of the second pool body 21. The particle size of the activated carbon layer 24 also gradually decreases, thereby ensuring that the water first contacts the large particles of activated carbon, then the medium particles, and finally the small particles. The oxygen aeration pipe 232 in this application is a membrane module aeration pipe, which is existing technology.

[0045] See appendix Figure 1 and Figure 2 As shown, in this utility model, the membrane filtration tank 3 includes a third tank body 31, a plurality of membrane modules 32 installed on the second connecting pipe group 20 and located inside the third tank body 31; a dosing component 41 is installed on the bottom surface of the inner cavity of the third tank body 31 and connected to the membrane modules 32; an outlet pipe 6 is located at the bottom of the third tank body 31, and a second pH sensor 44 connected to the controller is installed on the third tank body 31.

[0046] This invention utilizes a membrane module 32 for fine filtration of water. Since the membrane module 32 is prior art, it will not be described in detail here. A second pH sensor 44 is used to monitor the pH value of the water in the outlet pipe 6, ensuring that the pH value of the treated water is within a specified range. It should be noted that a solenoid valve is also installed on the outlet pipe 6, which can be controlled by a controller.

[0047] See appendix Figure 1 and Figure 2 As shown, in this utility model, the carbon dioxide dosing mechanism 4 includes a dosing component 41 for adding carbon dioxide to the activated carbon filter 2 and the membrane filter 3, a first pH sensor 42 installed on the inlet pipe 5, and a controller connected to the first pH sensor 42, which is connected to the dosing component 41.

[0048] This invention uses the addition component 41 to add carbon dioxide to the activated carbon filter 2 and the membrane filter 3 to change the pH value of the water; and uses the first pH sensor 42 to monitor the pH of the water.

[0049] See appendix Figure 1 and Figure 2 As shown, in this utility model, the dosing component 41 includes a carbon dioxide storage tank 411, an outlet pipe 412 installed on the carbon dioxide storage tank 411, a carbon dioxide metering pump 413 installed on the carbon dioxide storage tank 411, a main dosing pipe 414 installed on the outlet of the carbon dioxide metering pump 413, and two sets of carbon dioxide aeration pipes 415 installed on the main dosing pipe 414. The two sets of carbon dioxide aeration pipes 415 are located in the activated carbon filter 2 and the membrane filter 3, respectively.

[0050] This invention utilizes a carbon dioxide storage tank 411 for storing carbon dioxide; a carbon dioxide metering pump 413 for adding carbon dioxide into the water; and a carbon dioxide aeration pipe 415, configured in two sets, with one set fixed to the bottom of the support plate 23 by a saddle clip and the other set connected to the membrane module 32, to further ensure that aluminum ions do not pass through the membrane module 32, thus protecting the membrane module 32.

[0051] See appendix Figure 1 — Figure 5 As shown, the usage process of this utility model is as follows:

[0052] First, raw water enters the coagulation sedimentation tank 1 through the inlet pipe 5, impacting the flocculant dosing pipe 13. Simultaneously, the first pH sensor 42 transmits the pH value of the raw water to the controller. The controller then controls the flocculant metering pump 14 to add a measured amount of flocculant through the flocculant dosing pipe 13 into the mixing zone 122. The raw water and coagulant then mix and enter the sedimentation zone 123 through the water passage 124, where flocculation and sedimentation occur. Finally, the water passes through the filter screen 127 and enters the first connecting pipe. 11 flows into the activated carbon filter 2 and out from the bottom of the second tank 21. It passes through three activated carbon layers 24 in sequence. At the same time, the carbon dioxide metering pump 413 aerates the activated carbon filter 2 and the membrane filter 3 through the carbon dioxide aeration pipe 415. After passing through the three activated carbon layers 24, the water flows into the membrane module 32 through the second connecting pipe group 20. It enters from the inside of the membrane module 32 and flows out from the outside. Finally, it leaves the factory through the effluent pipe 6. A second pH sensor 44 is also installed on the effluent pipe 6.

[0053] The above embodiments are illustrative of this application and are not intended to limit this application. Any simple modifications to this application are within the protection scope of this application.

Claims

1. A high-pH raw water treatment device, characterized in that, Includes a coagulation sedimentation tank (1), an inlet pipe (5) installed at one end of the coagulation sedimentation tank (1), a first connecting pipe (11) installed at the other end of the coagulation sedimentation tank (1), an activated carbon filter (2) connected to the coagulation sedimentation tank (1) through the first connecting pipe (11), a second connecting pipe group (20) installed on the activated carbon filter (2), a membrane filter (3) connected to the activated carbon filter (2) through the second connecting pipe group (20), a carbon dioxide dosing mechanism (4) connected to the activated carbon filter (2) and the membrane filter (3), and an outlet pipe (6) installed on the membrane filter (3). The carbon dioxide dosing mechanism (4) includes a dosing component (41) for adding carbon dioxide to the activated carbon filter (2) and the membrane filter (3), a first pH sensor (42) installed on the inlet pipe (5), and a controller connected to the first pH sensor (42) and the dosing component (41).

2. The high pH raw water treatment device according to claim 1, characterized in that, The coagulation sedimentation tank (1) includes a first tank body (12), a flocculant delivery pipe (13) installed in the first tank body (12), and a flocculant metering pump (14) installed at one end of the flocculant delivery pipe (13). The first pool body (12) is provided with a partition block (121), which divides the internal space of the first pool body (12) into a mixing zone (122) and a sedimentation zone (123).

3. The high pH raw water treatment device according to claim 2, characterized in that, One end of both the flocculant delivery pipe (13) and the water inlet pipe (5) is located within the mixing zone (122); The flocculant delivery pipe (13) is provided with 5 delivery holes (131) at equal intervals, and the flocculant delivery pipe (13) is also provided with a one-way valve (132). The orientation of the flocculant delivery pipe (13) is perpendicular to that of the inlet pipe (5), and the minimum distance between the installation position of the flocculant delivery pipe (13) and the bottom surface of the first pool body (12) is equal to the minimum distance between the installation position of the inlet pipe (5) and the bottom surface of the first pool body (12).

4. The high pH raw water treatment device according to claim 2, characterized in that, A water passage (124) is formed between the partition block (121) and the bottom surface of the inner cavity of the first pool body (12). The bottom surface of the partition block (121) is provided with a guide surface (125). The guide surface (125) and the bottom surface of the first pool body (12) form an angle with the opening facing the water inlet pipe (5). The angle is an acute angle.

5. The high pH raw water treatment device according to claim 2, characterized in that, The sedimentation zone (123) is provided with a sedimentation frame (126), a filter screen (127) is installed on the sedimentation frame (126), and a hook bolt (128) is installed on the sedimentation frame (126). The distance between the first connecting pipe (11) and the bottom surface of the first pool body (12) is greater than the height of the sedimentation frame (126).

6. The high pH raw water treatment device according to claim 1, characterized in that, The activated carbon filter (2) includes a second tank body (21), multiple mounting platforms (22) set in the second tank body (21), a support plate (23) installed on the mounting platform (22), and an activated carbon layer (24) filled on the support plate (23). Each of the support plates (23) has two sets of saddle clips staggered at the bottom, one set of which is used to support the dosing component (41).

7. The high pH raw water treatment device according to claim 6, characterized in that, The support plate (23) is provided with through holes (231), the diameter of which is smaller than the particle size of the activated carbon layer (24); The bottom of the support plate (23) is fitted with an oxygen aeration pipe (232) via another set of saddle clips.

8. The high pH raw water treatment device according to claim 1, characterized in that, The membrane filtration tank (3) includes a third tank body (31) and a plurality of membrane modules (32) installed on the second connecting pipe group (20) and located inside the third tank body (31); the dosing component (41) is installed on the bottom surface of the inner cavity of the third tank body (31) and connected to the membrane modules (32).

9. The high pH raw water treatment device according to claim 8, characterized in that, The outlet pipe (6) is located at the bottom of the third pool (31), and a second pH sensor (44) connected to the controller is installed on the third pool (31).

10. The high pH raw water treatment device according to claim 1, characterized in that, The dosing assembly (41) includes a carbon dioxide storage tank (411), an outlet pipe (412) installed on the carbon dioxide storage tank (411), a carbon dioxide metering pump (413) installed on the carbon dioxide storage tank (411), a main dosing pipe (414) installed on the outlet of the carbon dioxide metering pump (413), and two sets of carbon dioxide aeration pipes (415) installed on the main dosing pipe (414). The two sets of carbon dioxide aeration pipes (415) are located in the activated carbon filter (2) and the membrane filter (3), respectively.

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