A system for removing impurity metal ions and compounds from a sodium pyrophosphate crude product

Abstract

This invention discloses a system for removing impurities such as metal ions and compounds from crude sodium pyrophosphate, belonging to the field of crude sodium pyrophosphate refining technology. It includes a dissolving vessel equipped with a water inlet pipe, a crude sodium pyrophosphate inlet, a first hydrogen peroxide inlet pipe, a composite flocculant inlet pipe, a first pH adjuster inlet pipe, and a first discharge pipe. The first discharge pipe is connected to a first filter, which is connected to a reaction vessel via a first connecting pipe. The reaction vessel is equipped with a second hydrogen peroxide inlet pipe, a chlorine dioxide inlet pipe, an activated carbon inlet, a second pH adjuster inlet pipe, and a second discharge pipe. The second discharge pipe is connected to a second filter, which is connected to a crystallizer via a second connecting pipe. The crystallizer is connected to a centrifugal separator, which is connected to an oven. This invention can obtain high-purity sodium pyrophosphate products.

Description

Technical Field

[0001] This invention belongs to the field of crude sodium pyrophosphate refining technology, specifically relating to a system for removing impurity metal ions and compounds from crude sodium pyrophosphate. Background Technology

[0002] With the Ministry of Industry and Information Technology's Announcement No. 1158 explicitly prohibiting the sale of glyphosate aqueous solutions with an effective ingredient content of less than 30%, more than 1.5 million tons / year of high-concentration glyphosate wastewater in China cannot be sold as a commodity (containing more than 35,000 tons / year of phosphorus). The common practice of glyphosate manufacturers is to incinerate the wastewater, where the organic components are pyrolyzed, and a crude pyrophosphate byproduct with a content of about 80% is obtained. Crude sodium pyrophosphate contains a lot of heavy metals and organic impurities and cannot be used directly.

[0003] Currently, there are few technologies for utilizing crude sodium pyrophosphate, and the existing technologies for utilizing crude sodium pyrophosphate produce poor-quality recycled products, which are all industrial-grade products (such as patents CN106809812A and CN106335889A). Therefore, the product value is very low. In addition, the recycling methods themselves are costly. As a result, these recycling solutions are not economical or practical, making it difficult to promote and apply them in industry and failing to solve the technical problem of the difficulty in recycling large quantities of crude sodium pyrophosphate.

[0004] Chinese patent CN111646448A, published on September 11, 2020, discloses a method for preparing food-grade sodium pyrophosphate from glyphosate byproduct crude sodium pyrophosphate, comprising the following steps: S1, dissolving crude sodium pyrophosphate in water at a volume ratio of 1:3 to 5 at 80–90°C under stirring, controlling the system temperature at 70–95°C, reacting for 30–60 minutes, and then allowing the mixture to stand at this temperature for 10–30 minutes after the reaction is complete to obtain a first reaction solution; S2, filtering to remove insoluble mechanical impurities from the first reaction solution. The mixture is purified to obtain a clear liquid. Then, 0.1–1% hydrogen peroxide (by mass) is added to the clear liquid until the pH reaches 8–9, at which point the addition of hydrogen peroxide is stopped. Next, K₂S or Na₂S is added, with a mass ratio of K₂S to the clear liquid of 0.05–0.1:100. The system temperature is then raised to 70–95°C and stirred at 20–30 r / min for 5–20 min. Finally, polyaluminum chloride (PAC) is added, with a mass ratio of PAC to the clear liquid of 0.05–0.1:100. After thorough dispersion, let stand for 10-30 minutes to obtain the second reaction solution; S3, filter the second reaction solution to obtain the filtrate, evaporate and concentrate the filtrate, evaporating 30-60% of the total mass of the second reaction solution to obtain the concentrate, then cool the concentrate with chilled water at 0-5°C. After the first crystallization occurs, separate the first crystallization, and the residual liquid phase is the first mother liquor; S4, mix the first crystallization with deionized water at 80-90°C at a volume ratio of 1:3-5. The solution is dissolved under stirring, with the system temperature controlled at 70–95°C, and reacted for 30–60 minutes. After the reaction is complete, it is kept at this temperature and allowed to stand for 10–30 minutes to obtain the third reaction solution. Then, the third reaction solution is cooled with 0–5°C chilled water until the second crystallization occurs. The second crystallization is then separated, and the residual liquid phase is the second mother liquor. S5. The second crystallization is heated to 350–400°C for 60–100 minutes to obtain the heated product. The heated product is then ground to obtain sodium pyrophosphate. This patent uses hydrogen peroxide + K2S or Na2S + polyaluminum chloride to remove heavy metals and organic impurities. However, the sodium pyrophosphate prepared by this patent has the disadvantages of low purity and high production cost. Utility Model Content

[0005] The purpose of this invention is to solve the problems of the prior art and provide a system for removing impurity metal ions and compounds from crude sodium pyrophosphate. Crude sodium pyrophosphate is added to a dissolving vessel through a crude sodium pyrophosphate inlet, followed by demineralized water added to the dissolving vessel through an inlet pipe. The crude sodium pyrophosphate dissolves to obtain a sodium pyrophosphate solution. Hydrogen peroxide is then added through a first hydrogen peroxide inlet pipe to oxidize the low-valence iron and manganese ions in the sodium pyrophosphate solution to high-valence states. Next, a composite settling agent (comprising ethylenediaminetetraacetic acid and dimercaprol) is added through a composite settling agent inlet pipe. ethylenediaminetetraacetic acid has high selectivity for the oxidized high-valence iron, manganese, and lead ions. With strong chelating ability, dimercaprol can effectively bind mercury ions. A pH adjuster is added through the first pH adjuster inlet pipe, and the solution flows into the first filter through the first feed pipe, achieving efficient removal of various heavy metal impurities. The solution for removing precipitates flows into the reaction vessel through the first connecting pipe. Hydrogen peroxide is added through the second chlorine oxide inlet pipe, and chlorine dioxide is added through the chlorine dioxide inlet pipe. Hydrogen peroxide and chlorine dioxide can oxidize and decompose organic impurities into small molecules such as carbon dioxide and water, thereby reducing the content of organic impurities. Activated carbon is added through the activated carbon inlet. Activated carbon has a rich porous structure and can adsorb small molecule organic impurities and possible pigments remaining after the oxidation reaction. Finally, a pH adjuster is added through the second pH adjuster inlet pipe, and the solution flows into the crystallizer through the second connecting pipe. Crystallization is carried out in the recrystallizer, and centrifugation is performed to obtain sodium pyrophosphate crystals. The sodium pyrophosphate crystals are washed three times with a small amount of deionized water and dried in an oven to obtain a high-purity sodium pyrophosphate product. This invention can obtain a high-purity sodium pyrophosphate product.

[0006] This utility model is achieved through the following technical solution:

[0007] A system for removing impurity metal ions and compounds from crude sodium pyrophosphate includes a dissolving vessel. The dissolving vessel is equipped with a water inlet pipe, a crude sodium pyrophosphate inlet, a first hydrogen peroxide inlet pipe, a composite flocculant inlet pipe, a first pH adjuster inlet pipe, and a first discharge pipe. The first discharge pipe is connected to a first filter, which is connected to a reaction vessel via a first connecting pipe. The reaction vessel is equipped with a second hydrogen peroxide inlet pipe, a chlorine dioxide inlet pipe, an activated carbon inlet, a second pH adjuster inlet pipe, and a second discharge pipe. The second discharge pipe is connected to a second filter, which is connected to a crystallizer via a second connecting pipe. The crystallizer is connected to a centrifugal separator, which is connected to an oven.

[0008] Preferably, the dissolving vessel is provided with a first temperature control unit, which includes a first temperature sensor and a first heat exchange jacket on the dissolving vessel. The first heat exchange jacket is provided with a first heat exchange inlet pipe and a first heat exchange outlet pipe, and the first heat exchange inlet pipe is provided with a first heat exchange valve.

[0009] Preferably, the reactor is provided with a second temperature control unit, which includes a second temperature sensor and a second heat exchange jacket. The second heat exchange jacket is provided with a second heat exchange inlet pipe and a second heat exchange outlet pipe, and the second heat exchange inlet pipe is provided with a second heat exchange valve.

[0010] Preferably, the dissolving vessel is equipped with a first stirring device.

[0011] Preferably, the reactor is equipped with a second stirring device.

[0012] Preferably, a first pH meter is provided on the dissolving vessel.

[0013] Preferably, a second pH meter is provided on the reaction vessel.

[0014] Preferably, both the first and second filters are plate and frame filters.

[0015] Preferably, each of the following pipes is equipped with a switch valve: water inlet pipe, first hydrogen peroxide inlet pipe, composite flocculant inlet pipe, first pH adjuster inlet pipe, first discharge pipe, second hydrogen peroxide inlet pipe, chlorine dioxide inlet pipe, second pH adjuster inlet pipe, and second discharge pipe.

[0016] Preferably, flow meters are installed on the water inlet pipe, the first hydrogen peroxide inlet pipe, the composite flocculant inlet pipe, the first pH adjuster inlet pipe, the second hydrogen peroxide inlet pipe, the chlorine dioxide inlet pipe, and the second pH adjuster inlet pipe.

[0017] Compared with the prior art, this utility model has the following advantages and beneficial effects:

[0018] I. This utility model provides a system for removing impurity metal ions and compounds from crude sodium pyrophosphate. The crude sodium pyrophosphate is added to a dissolving vessel through a crude sodium pyrophosphate inlet. Subsequently, demineralized water is added to the dissolving vessel through an inlet pipe. The crude sodium pyrophosphate dissolves to obtain a sodium pyrophosphate solution. Then, hydrogen peroxide is added through a first hydrogen peroxide inlet pipe to oxidize the low-valence iron and manganese ions in the sodium pyrophosphate solution to high-valence states. Next, a composite precipitant (comprising ethylenediaminetetraacetic acid and dimercaprol) is added through a composite precipitant inlet pipe. ethylenediaminetetraacetic acid has high selectivity and strong chelating ability for the oxidized high-valence iron, manganese, and lead ions. Dimercaptopropanol effectively binds mercury ions. A pH adjuster is added through the first pH adjuster inlet pipe, and the solution flows into the first filter through the first feed pipe, achieving efficient removal of various heavy metal impurities. The solution for removing precipitates flows into the reaction vessel through the first connecting pipe. Hydrogen peroxide is added through the second chlorine oxide inlet pipe, and chlorine dioxide is added through the chlorine dioxide inlet pipe. Hydrogen peroxide and chlorine dioxide can oxidize and decompose organic impurities into small molecules such as carbon dioxide and water, thereby reducing the content of organic impurities. Activated carbon is added through the activated carbon inlet. Activated carbon has a rich porous structure and can adsorb small molecule organic impurities and possible pigments remaining after the oxidation reaction. Finally, a pH adjuster is added through the second pH adjuster inlet pipe, and the solution flows into the crystallizer through the second connecting pipe. Crystallization is carried out in the recrystallizer, and centrifugation is performed to obtain sodium pyrophosphate crystals. The sodium pyrophosphate crystals are washed three times with a small amount of deionized water and dried in an oven to obtain a high-purity sodium pyrophosphate product. This invention can obtain a high-purity sodium pyrophosphate product. This system employs a multi-stage treatment process of "oxidation-chelation precipitation-deep oxidation-activated carbon adsorption," combined with precise temperature and pH control, to achieve the removal of heavy metal ions. The efficient removal of organic impurities significantly improves product purity.

[0019] II. The present invention provides a system for removing impurity metal ions and compounds from crude sodium pyrophosphate. The first temperature control unit facilitates the adjustment of the temperature inside the dissolving vessel, resulting in more thorough dissolution of crude sodium pyrophosphate and better precipitation of metal impurities.

[0020] III. The present invention provides a system for removing impurity metal ions and compounds from crude sodium pyrophosphate. The second temperature control unit facilitates the adjustment of the temperature inside the reactor, resulting in better oxidation, adsorption, and crystallization of organic matter in the crude sodium pyrophosphate.

[0021] IV. The present invention provides a system for removing impurity metal ions and compounds from crude sodium pyrophosphate. The setting of the first pH meter and the second pH meter, in conjunction with the first pH adjuster inlet pipe and the second pH adjuster inlet pipe, facilitates the adjustment of the pH value in the dissolving vessel and the reaction vessel.

[0022] V. The present invention provides a system for removing impurity metal ions and compounds from crude sodium pyrophosphate. The setting of the switching valve and flow meter facilitates material feeding and unloading. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of this utility model;

[0024] Figure 2 This is a schematic diagram of the structure of Embodiment 2 of this utility model.

[0025] The components include: 1. Dissolving vessel; 2. First hydrogen peroxide inlet pipe; 3. Composite flocculant inlet pipe; 4. First pH adjuster inlet pipe; 5. First feed pipe; 6. First filter; 7. First connecting pipe; 8. Reactor; 9. Second hydrogen peroxide inlet pipe; 10. Chlorine dioxide inlet pipe; 11. Activated carbon inlet; 12. Second pH adjuster inlet pipe; 13. Second feed pipe; 14. Second filter; 15. Second connecting pipe; 16. Crystallizer; 17. Centrifugal separator; 18. Drying oven; 19. 20. First temperature sensor; 21. First heat exchange jacket; 22. First heat exchange inlet pipe; 23. First heat exchange outlet pipe; 24. First heat exchange valve; 25. Second heat exchange jacket; 26. Second heat exchange inlet pipe; 27. Second heat exchange outlet pipe; 28. Second heat exchange valve; 29. ​​First stirring device; 30. Second stirring device; 31. First pH meter; 32. Second pH meter; 33. Switch valve; 34. Flow meter; 35. Sodium pyrophosphate crude product inlet; 36. Water inlet pipe. Detailed Implementation

[0026] The present invention will be further described in detail below with reference to the embodiments, but the implementation of the present invention is not limited thereto.

[0027] Example 1

[0028] like Figure 1 As shown, this embodiment provides a system for removing impurity metal ions and compounds from crude sodium pyrophosphate, including a dissolving vessel 1. The dissolving vessel 1 is equipped with a water inlet pipe 36, a crude sodium pyrophosphate inlet 35, a first hydrogen peroxide inlet pipe 2, a composite flocculant inlet pipe 3, a first pH adjuster inlet pipe 4, and a first discharge pipe 5. The first discharge pipe 5 is connected to a first filter 6. The first filter 6 is connected to a reaction vessel 8 through a first connecting pipe 7. The reaction vessel 8 is equipped with a second hydrogen peroxide inlet pipe 9, a chlorine dioxide inlet pipe 10, an activated carbon inlet 11, a second pH adjuster inlet pipe 12, and a second discharge pipe 13. The second discharge pipe 13 is connected to a second filter 14. The second filter 14 is connected to a crystallizer 16 through a second connecting pipe 15. The crystallizer 16 is connected to a centrifugal separator 17, and the centrifugal separator 17 is connected to an oven 18.

[0029] Example 2

[0030] like Figure 2 As shown, this embodiment provides a system for removing impurity metal ions and compounds from crude sodium pyrophosphate, including a dissolving vessel 1. The dissolving vessel 1 is equipped with a water inlet pipe 36, a crude sodium pyrophosphate inlet 35, a first hydrogen peroxide inlet pipe 2, a composite flocculant inlet pipe 3, a first pH adjuster inlet pipe 4, and a first discharge pipe 5. The first discharge pipe 5 is connected to a first filter 6. The first filter 6 is connected to a reaction vessel 8 through a first connecting pipe 7. The reaction vessel 8 is equipped with a second hydrogen peroxide inlet pipe 9, a chlorine dioxide inlet pipe 10, an activated carbon inlet 11, a second pH adjuster inlet pipe 12, and a second discharge pipe 13. The second discharge pipe 13 is connected to a second filter 14. The second filter 14 is connected to a crystallizer 16 through a second connecting pipe 15. The crystallizer 16 is connected to a centrifugal separator 17, and the centrifugal separator 17 is connected to an oven 18.

[0031] The dissolving vessel 1 is provided with a first temperature control unit, which includes a first temperature sensor 19 and a first heat exchange jacket 20. The first heat exchange jacket 20 is provided with a first heat exchange inlet pipe 21 and a first heat exchange outlet pipe 22. The first heat exchange inlet pipe 21 is provided with a first heat exchange valve 23.

[0032] The reactor 8 is provided with a second temperature control unit, which includes a second temperature sensor 24 and a second heat exchange jacket 25. The second heat exchange jacket 25 is provided with a second heat exchange inlet pipe 26 and a second heat exchange outlet pipe 27. The second heat exchange inlet pipe 26 is provided with a second heat exchange valve 28.

[0033] The dissolving vessel 1 is equipped with a first stirring device 29.

[0034] The reactor 8 is equipped with a second stirring device 30.

[0035] The dissolving vessel 1 is equipped with a first pH meter 31.

[0036] The reactor 8 is equipped with a second pH meter 32.

[0037] Both the first filter 6 and the second filter 14 are plate and frame filters.

[0038] Each of the following pipes is equipped with a switch valve 33: water inlet pipe 36, first hydrogen peroxide inlet pipe 2, composite flocculant inlet pipe 3, first pH adjuster inlet pipe 4, first discharge pipe 5, second hydrogen peroxide inlet pipe 9, chlorine dioxide inlet pipe 10, second pH adjuster inlet pipe 12, and second discharge pipe 13.

[0039] Flow meters 34 are installed on the water inlet pipe 36, the first hydrogen peroxide inlet pipe 2, the composite flocculant inlet pipe 3, the first pH adjuster inlet pipe 4, the second hydrogen peroxide inlet pipe 9, the chlorine dioxide inlet pipe 10, and the second pH adjuster inlet pipe 12.

[0040] Compared with the prior art, this utility model has the following advantages and beneficial effects:

[0041] I. This utility model provides a system for removing impurity metal ions and compounds from crude sodium pyrophosphate. The crude sodium pyrophosphate is added to a dissolving vessel 1 through the crude sodium pyrophosphate inlet 35. Subsequently, demineralized water is added to the dissolving vessel 1 through the inlet pipe 36. The crude sodium pyrophosphate dissolves to obtain a sodium pyrophosphate solution. Then, hydrogen peroxide is added through the first hydrogen peroxide inlet pipe 2 to oxidize the low-valence iron and manganese ions in the sodium pyrophosphate solution to high-valence states. Next, a composite settling agent (comprising ethylenediaminetetraacetic acid and dimercaprol) is added through the composite settling agent inlet pipe 3. ethylenediaminetetraacetic acid has high selectivity and strong chelating ability for the oxidized high-valence iron, manganese, and lead ions. Dimercaprol... Propanol effectively binds mercury ions. A pH adjuster is added through the first pH adjuster inlet pipe 4, and then flows into the first filter 6 through the first feed pipe 5, achieving efficient removal of various heavy metal impurities. The solution for removing precipitates flows into the reaction vessel 8 through the first connecting pipe 7. Hydrogen peroxide is added through the second chlorine oxide inlet pipe 10, and chlorine dioxide is added through the chlorine dioxide inlet pipe 10. Hydrogen peroxide and chlorine dioxide can oxidize and decompose organic impurities into small molecules such as carbon dioxide and water, thereby reducing the content of organic impurities. Activated carbon is added through the activated carbon inlet 11. Activated carbon has a rich porous structure and can adsorb small molecule organic impurities and possible pigments remaining after the oxidation reaction. Finally, a pH adjuster is added through the second pH adjuster inlet pipe 12, and then flows into the crystallizer 16 through the second connecting pipe 15. Crystallization is carried out in the recrystallizer 16, and centrifugation is performed through the centrifuge separation device 17 to obtain sodium pyrophosphate crystals. The sodium pyrophosphate crystals are washed three times with a small amount of deionized water and dried in the oven 18 to obtain a high-purity sodium pyrophosphate product. This invention yields high-purity sodium pyrophosphate. The system employs a multi-stage treatment process involving oxidation, chelation precipitation, deep oxidation, and activated carbon adsorption, combined with precise temperature and pH control, to achieve the removal of heavy metal ions. The efficient removal of organic impurities significantly improves product purity.

[0042] II. The present invention provides a system for removing impurity metal ions and compounds from crude sodium pyrophosphate. The first temperature control unit facilitates the adjustment of the temperature inside the dissolving vessel 1, resulting in more thorough dissolution of crude sodium pyrophosphate and better precipitation of metal impurities.

[0043] III. The present invention provides a system for removing impurity metal ions and compounds from crude sodium pyrophosphate. The second temperature control unit facilitates the adjustment of the temperature inside the reaction vessel 8, resulting in better oxidation, adsorption, and crystallization effects of organic matter in the crude sodium pyrophosphate.

[0044] IV. The present invention provides a system for removing impurity metal ions and compounds from crude sodium pyrophosphate. The first pH meter 31 and the second pH meter 32 are set up in conjunction with the first pH adjuster inlet pipe 4 and the second pH adjuster inlet pipe 12 to facilitate the adjustment of pH values ​​in the dissolving vessel 1 and the reaction vessel 8.

[0045] V. The present invention provides a system for removing impurity metal ions and compounds from crude sodium pyrophosphate. The setting of the switching valve 33 and the flow meter 34 facilitates material feeding and unloading.

[0046] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present utility model shall fall within the protection scope of the present utility model.

Claims

1. A system for removing impurity metal ions and compounds from a crude sodium pyrophosphate, characterized by: The apparatus includes a dissolving vessel (1), which is equipped with a water inlet pipe (36), a crude sodium pyrophosphate inlet (35), a first hydrogen peroxide inlet pipe (2), a composite precipitant inlet pipe (3), a first pH adjuster inlet pipe (4), and a first feed pipe (5). The first feed pipe (5) is connected to a first filter (6), which is connected to a reaction vessel (8) via a first connecting pipe (7). The reaction vessel (8) is equipped with a second hydrogen peroxide inlet pipe (9), a chlorine dioxide inlet pipe (10), an activated carbon inlet (11), a second pH adjuster inlet pipe (12), and a second feed pipe (13). The second feed pipe (13) is connected to a second filter (14), which is connected to a crystallizer (16) via a second connecting pipe (15). The crystallizer (16) is connected to a centrifugal separator (17), which is connected to an oven (18).

2. A system for removing impurity metal ions and compounds from a crude sodium pyrophosphate according to claim 1, characterized in that: The dissolving vessel (1) is provided with a first temperature control unit. The first temperature control unit includes a first temperature sensor (19) provided on the dissolving vessel (1) and a first heat exchange jacket (20) provided on the dissolving vessel (1). The first heat exchange jacket (20) is provided with a first heat exchange inlet pipe (21) and a first heat exchange outlet pipe (22). The first heat exchange inlet pipe (21) is provided with a first heat exchange valve (23).

3. The system for removing impurity metal ions and compounds from crude sodium pyrophosphate according to claim 1, characterized in that: The reactor (8) is provided with a second temperature control unit. The second temperature control unit includes a second temperature sensor (24) provided on the reactor (8) and a second heat exchange jacket (25) provided on the reactor (8). The second heat exchange jacket (25) is provided with a second heat exchange inlet pipe (26) and a second heat exchange outlet pipe (27). The second heat exchange inlet pipe (26) is provided with a second heat exchange valve (28).

4. The system for removing impurity metal ions and compounds from a sodium pyrophosphate crude product according to claim 1, characterized in that: The dissolving vessel (1) is equipped with a first stirring device (29).

5. A system for removing impurity metal ions and compounds from a crude sodium pyrophosphate according to claim 1, characterized in that: The reactor (8) is equipped with a second stirring device (30).

6. A system for removing impurity metal ions and compounds from a crude sodium pyrophosphate according to claim 1, characterized in that: The dissolving vessel (1) is equipped with a first pH meter (31).

7. The system for removing impurity metal ions and compounds from crude sodium pyrophosphate according to claim 1, characterized in that: A second pH meter (32) is installed on the reactor (8).

8. A system for removing impurity metal ions and compounds from a crude sodium pyrophosphate according to claim 1, characterized in that: Both the first filter (6) and the second filter (14) are plate and frame filters.

9. A system for removing impurity metal ions and compounds from a crude sodium pyrophosphate according to claim 1, characterized in that: A switch valve (33) is provided on the water inlet pipe (36), the first hydrogen peroxide inlet pipe (2), the composite flocculant inlet pipe (3), the first pH adjuster inlet pipe (4), the first discharge pipe (5), the second hydrogen peroxide inlet pipe (9), the chlorine dioxide inlet pipe (10), the second pH adjuster inlet pipe (12), and the second discharge pipe (13).

10. The system for removing impurity metal ions and compounds from a sodium pyrophosphate crude product according to claim 1, characterized in that: A flow meter (34) is installed on each of the water inlet pipe (36), the first hydrogen peroxide inlet pipe (2), the composite flocculant inlet pipe (3), the first pH adjuster inlet pipe (4), the second hydrogen peroxide inlet pipe (9), the chlorine dioxide inlet pipe (10), and the second pH adjuster inlet pipe (12).

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