Crystal bead fluidization reaction sewage treatment process

Abstract

The invention relates to the technical field of sewage treatment, in particular to a crystal bead fluidization reaction sewage treatment process which comprises the following steps: 1) sewage enters a crystal bead fluidization tower and is in contact with a precipitant under gas stripping to generate small-particle precipitates; 2) combining the small-particle precipitate with the seed crystal to form a prototype of crystal beads, and continuously fluidizing and circulating in a crystal bead fluidizing area to form mature crystal beads; (3) precipitating and gathering mature crystal beads at the bottom of the crystal bead fluidization tower, and discharging from a crystal bead collecting opening; sewage passes through the clarification area and is discharged from the water outlet; the method comprises the following steps: a) mixing water discharged from a crystal bead fluidization tower with a coagulant to form a small floc mixture; b) feeding the small floc mixture into the efficient separation tower, contacting with a flocculating agent, and circularly fluidizing under the action of gas stripping until the large floc is large and settles to the bottom of the efficient separation tower, and c) discharging the large floc from a sludge discharge port at the bottom of the efficient separation tower, mixing the large floc with the sewage, and feeding the mixed floc into the crystal bead fluidization tower. The sludge discharge amount is small, and the sewage treatment equipment occupies a small area.

Description

Technical Field

[0001] The present application relates to the technical field of sewage treatment, and in particular to a crystal bead fluidized bed reaction sewage treatment process. Background Art

[0002] For wastewater containing one or more pollutants such as high hardness, high silicon, high fluorine, high phosphorus, and heavy metals, a series of treatments will be carried out on the wastewater in order to reduce the content of pollutants in the water as much as possible and meet the effluent requirements.

[0003] The Chinese patent application number 201810496242.2 discloses a method and device suitable for removing hardness from high-hardness wastewater, comprising the following steps: (1) First, the sewage passes through a primary coagulation tank, a secondary coagulation tank and a circulating clarification tank in sequence for primary sedimentation treatment to remove most of the hardness of the sewage, most of which refers to temporary hardness and part of permanent hardness; (2) Then, the sewage that has undergone primary sedimentation treatment passes through a high-efficiency sedimentation tank that integrates a coagulation zone, a flocculation zone and a sedimentation-concentration zone for secondary clarification treatment to remove the permanent hardness of the sewage. Conventional treatment methods are to use a primary sedimentation method + a secondary sedimentation method, and the sedimentation process can usually be a high-efficiency sedimentation tank, a loading sedimentation tank, etc. The basic removal principle is a chemical precipitation reaction. When a two-stage sedimentation method is used, the following problems will occur.

[0004] The applicant believes that although the above-mentioned related technologies have solved the technical problem of unsatisfactory hardness treatment effect of existing wastewater hardness treatment methods, they still have the following defects: (1) The two-stage sedimentation occupies a relatively large area and is difficult to arrange in sites with limited land; (2) The amount of sludge is relatively large. Due to the high content of pollutants, the sludge produced will be relatively large and can only be treated as hazardous waste; (3) The amount of added chemicals is relatively large and the treatment cost is relatively high. Summary of the invention

[0005] In order to reduce the floor space occupied by sewage treatment equipment, reduce sludge discharge, and reduce the amount of added chemicals, the present application provides a crystal bead fluidized bed reaction sewage treatment process.

[0006] A crystal bead fluidized bed reaction wastewater treatment process adopts the following technical scheme.

[0007] A crystal bead fluidized bed reaction wastewater treatment process comprises the following steps: S1. Crystal bead fluidization: 1) The sewage enters the crystal bead fluidized bed tower and contacts with the precipitant in the crystal bead fluidized bed area under the action of gas lift. The precipitant reacts with the pollutants in the sewage to form small particle precipitation; 2) The generated small particle precipitation combines with the crystal seed to begin to form the prototype of the crystal bead. Through the continuous entry of raw water and gas, the formed prototype crystal bead is suspended in the crystal bead fluidization zone, and then continuously contacts and wraps with the newly formed small particle precipitation, and continuously fluidizes and circulates in the crystal bead fluidization zone to finally form mature crystal beads; 3) The mature crystal beads are precipitated and gathered at the bottom of the crystal bead fluidized bed tower and discharged from the crystal bead collection port; the wastewater after the reaction passes through the clarification area and is discharged from the outlet; S2. Secondary separation a) The water discharged from the outlet of the crystal bead fluidized bed tower is mixed with the coagulant to form a small floc mixture; b) The small flocs mixture enters the high-efficiency separation tower and contacts with the flocculant under the action of air lift. The small flocs gradually become larger and circulate and fluidize under the action of air lift until the large flocs are large enough to settle to the bottom of the high-efficiency separation tower. c) The large flocs are discharged from the sludge outlet at the bottom of the high-efficiency separation tower, and then mixed with sewage and enter the crystal bead fluidized bed tower again.

[0008] By adopting the above technical solution, the sewage is acted upon by the precipitant, and the precipitant reacts with the pollutants to generate small particle precipitation, which is then adsorbed by the crystal seeds and wrapped around the crystal seeds to form the prototype of crystal beads. The prototype crystal beads are suspended in the crystal bead fluidization zone through the continuous entry of raw water and gas, and then continuously contact and wrap with the newly formed small particles, and continuously fluidize and circulate in the fluidization zone to eventually form mature crystal beads. At this time, the flow state formed is not enough to hold up the mature crystal beads, and the mature crystal beads will settle and gather at the bottom of the crystal bead fluidization tower and be discharged from the mature crystal bead collection port.

[0009] The effluent from the crystal bead fluidization still contains a certain amount of pollutants, which are then separated by precipitation after secondary separation to ensure the final effluent quality. The reagents do not need to be added excessively, and more than 20% of the reagents can be saved. In addition, the sludge obtained after the secondary separation will be returned to the crystal bead fluidization tower again, and then discharged after forming mature crystal beads. The final discharge is mature large crystal beads, which can be recycled, without the need for a sludge treatment system, and the equipment cost is low.

[0010] Furthermore, the rising velocity of the water flow in the crystal bead fluidized bed tower is 60-100 m / h, and the rising velocity of the water flow in the high-efficiency separation tower is 20-60 m / h.

[0011] Furthermore, the rising velocity of the water flow in the crystal bead fluidized bed tower is 80-100 m / h.

[0012] By adopting the above technical solution, the rising flow rate is high, and the entire process of crystal bead fluidization can be completed with integrated equipment, which can reduce the land occupation by more than 50%.

[0013] Furthermore, the seed crystal is at least one of quartz sand or garnet.

[0014] Furthermore, the seed crystal has a particle size of 0.1-0.3 mm.

[0015] Furthermore, the seed crystal is a composite modified seed crystal, and the modification method thereof is: i) mixing sodium hypochlorite and glacial acetic acid to obtain a mixed solution, using the mixed solution to oxidize seed crystals, soaking the oxidized seed crystals in a urea solution, reacting at 60-65° C. for 2 hours, and then filtering, washing, and drying to obtain amino-seed crystals; ii) Calcium chloride and aluminum chloride are dissolved and mixed to obtain a modified solution, the pH value of the modified solution is adjusted to 10, amino-seed crystals are added to the modified solution, and the reaction is oscillated at 60-65° C. for 3 hours, and then filtered, dried, washed, and dried to obtain composite modified seed crystals.

[0016] Furthermore, the weight ratio of calcium chloride to aluminum chloride is (2-4):1.

[0017] Furthermore, the concentration of the urea solution is 2-3 mol / L.

[0018] By adopting the above technical scheme, quartz sand or garnet is used as a seed crystal and modified. First, amino groups are grafted on the surface of the seed crystal through urea modification, so that the surface of the seed crystal presents grooves of a certain width and depth, and the surface roughness and specific surface area are increased, providing more grafting sites for subsequent calcium ions and aluminum ions. Then calcium chloride and aluminum chloride are used for composite grafting to graft calcium ions and aluminum ions on the seed crystal, so that the lamellar crystal structure presented on the surface of the seed crystal is composed of a large number of aggregated micron plates with high specific surface area, with irregular directions and sizes, which greatly improves the adsorption effect on small particle precipitation; these lamellar crystals composed of aluminum and calcium ions have physical properties that can be exchanged between layers, promote the growth and maturation of crystal beads, and improve the crystallization effect.

[0019] Furthermore, different precipitants are selected according to the different pollutants in the sewage. When the sewage needs to be de-hardened, the precipitant is NaOH solution; when the sewage needs to be de-F - When the precipitant is calcium salt solution; the sewage needs to remove PO4 3- When the precipitant is an iron salt solution.

[0020] Furthermore, when the sewage needs to be de-hardened, the pH value of the effluent from the crystal bead fluidized bed tower is 9.5-10.3; - When the pH value of the effluent from the crystal bead fluidized bed tower is 8.5-9.0, the wastewater needs to be de-PO4 3- At this time, the pH value of the effluent from the crystal bead fluidized bed tower is 3-5.

[0021] By adopting the above technical solution, different sewage can be treated in a targeted manner, greatly improving the sewage purification effect.

[0022] In summary, this application has the following beneficial effects: (1) By adding crystal seeds, most of the sludge is discharged in the form of crystal beads; the sludge in the separation device is returned to the crystal bead fluidizing tower to form crystal beads for discharge; the amount of sludge is small, and the sludge treatment device is smaller; (2) Small footprint: The crystal bead fluidized bed reactor can reach 100m / h; the high-efficiency fluidized bed separation reactor can reach 60m / h; it can reduce the footprint by more than 50%; (3) Short construction period: the equipment is processed directly in the factory and transported directly to the site for installation. Only the equipment foundation needs to be provided, and the construction period can be shortened by 3-6 months; (4) Less dosage, more than 20% lower than traditional dosage; (5) Low investment, no civil engineering, small amount of mud, low investment in plate and frame filter press or even no need to set up, and no secondary lifting required. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the sewage treatment process flow of an embodiment of the present application. DETAILED DESCRIPTION

[0024] The present application is further described in detail below with reference to the embodiments.

[0025] Raw materials and intermediate preparation examples raw material The raw materials in the examples of the present application can all be obtained commercially.

[0026] Preparation Example Preparation Example 1 A composite modified seed crystal, the preparation method of which is: i) Sodium hypochlorite is mixed with glacial acetic acid to obtain a mixed solution with an effective chlorine concentration of 10% and a pH value of 5, the seed crystals are soaked in the mixed solution for 24 hours, the seed crystals are oxidized, the oxidized seed crystals are soaked in a 3 mol / L urea solution, reacted at 60°C for 2 hours, and then filtered, washed, and dried to obtain amino-seed crystals; ii) Calcium chloride and aluminum chloride in a weight ratio of 2:1 are dissolved and mixed to obtain a modified solution, 2 mol / L sodium hydroxide and 0.5 mol / L sodium carbonate are added, the pH value of the modified solution is adjusted to 10, the amino-seed crystals are immersed in the modified solution, and oscillate at 60° C. for 3 hours, and then filtered, dried, washed, and dried to obtain composite modified seed crystals.

[0027] Preparation Example 2 Different from Preparation Example 1, the weight ratio of calcium chloride to aluminum chloride in Preparation Example 2 is 3:1.

[0028] Preparation Example 3 Different from Preparation Example 1, the weight ratio of calcium chloride to aluminum chloride in Preparation Example 3 is 4:1.

[0029] Preparation Example 4 Different from Preparation Example 1, the weight ratio of calcium chloride to aluminum chloride in Preparation Example 4 is 5:1.

[0030] Preparation Example 5 Different from Preparation Example 1, the weight ratio of calcium chloride to aluminum chloride in Preparation Example 5 is 1:3. Example

[0031] Example 1 See attached Figure 1 , a crystal bead fluidized bed reaction wastewater treatment process, comprising the following steps: The sewage is fluoride-containing wastewater from a chemical plant. The specific water quality is shown in Table 1: Table 1 Water quality of fluoride-containing wastewater

[0032] S1. Crystal bead fluidization: 1) Sewage enters the water distribution area from the water inlet of the crystal bead fluidized tower and enters the water distribution area evenly through the water distribution pipe. The rising velocity of the water flow is 60m / h. At the same time, CaCl2 solution is added to the reagent dosing pipe as a precipitant and also enters the crystal bead fluidized area. NaOH is also added to adjust the pH value. Under the action of gas lift, the sewage contacts the precipitant, and the precipitant and F in the sewage are - Reaction to form small particles of precipitation; 2) The generated small particle precipitation combines with the quartz sand seed with a particle size of 0.1-0.3mm to begin to form the prototype of crystal beads. Through the continuous entry of raw water and gas, the formed prototype crystal beads are suspended in the crystal bead fluidization zone, and then continuously contact and wrap with the newly formed small particle precipitation, and continuously fluidize and circulate in the crystal bead fluidization zone to finally form mature crystal beads; 3) The mature crystal beads are precipitated and gathered at the bottom of the crystal bead fluidized bed tower and discharged from the crystal bead collection port; the wastewater after the reaction passes through the clarification area and is discharged from the outlet; the outlet of the crystal bead fluidized bed tower is equipped with a pH meter, which is interlocked with the addition of NaOH to control the pH value at 8.5-9, and is controlled and adjusted through the PLC interlock. S2. Secondary separation a) The water discharged from the outlet of the crystal bead fluidized bed tower is mixed with potassium aluminate coagulant to form a small floc mixture; b) The small flocs mixture enters the high-efficiency separation tower, and the water flow rises at a velocity of 60 m / h. Under the action of air lift, it contacts the flocculant, and the small flocs gradually become larger. Under the action of air lift, they circulate and fluidize until the large flocs are large enough to settle to the bottom of the high-efficiency separation tower. c) The large flocs are discharged from the sludge outlet at the bottom of the high-efficiency separation tower, and then mixed with sewage and enter the crystal bead fluidized bed tower again.

[0033] Example 2 Different from Example 1, the seed crystal in Example 2 is quartz sand with a particle size of 0.5-0.6 mm.

[0034] Example 3 Different from Example 1, in Example 3, the rising velocity of the water flow in the bead fluidized tower is 80 m / h, and the rising velocity of the water flow in the high-efficiency separation tower is 50 m / h.

[0035] Example 4 Different from Example 1, in Example 4, the rising velocity of the water flow in the bead fluidized tower is 100 m / h, and the rising velocity of the water flow in the high-efficiency separation tower is 40 m / h.

[0036] Embodiment 5-9 Different from Example 1, in Examples 5-9, the quartz sand was replaced by the composite modified seed crystals obtained by modifying the quartz sand using the methods of Preparation Examples 1-5, respectively.

[0037] Performance Testing The effluent quality in Examples 1-9 was tested, and the results are shown in Table 2.

[0038] Table 2 Water quality of the effluent from Examples 1-9

[0039] Combining Example 1 with Examples 3-4 and Table 2, it can be seen that the rising flow rate of the crystal bead fluidized bed tower can reach 100m / h, and the rising flow rate in the high-efficiency separation tower can reach 60m / h. The water quality of the effluent still meets the requirements. The high rising flow rate can meet the requirements of the vertically arranged integrated crystal bead fluidized bed tower and the integrated high-efficiency separation tower, reducing the equipment footprint.

[0040] Combining Example 1 with Examples 5-9 and Table 2, it can be seen that modifying the seed crystals can further improve the sewage treatment effect, among which the modification process in Example 6 is the best. This may be because the lamellar crystal structure presented on the surface of the modified seed crystals is composed of a large number of aggregated micron plates with high specific surface area, with irregular directions and sizes, which greatly improves the adsorption of small particle precipitation; these lamellar crystals composed of aluminum and calcium ions have the physical property of interlayer exchange, which promotes the growth and maturation of crystal beads and improves the crystallization effect.

[0041] Example 10 A crystal bead fluidized bed reaction sewage treatment process comprises the following steps: The sewage is iron phosphate wastewater, and the specific water quality is shown in Table 3: Table 3 Water quality of iron phosphate wastewater

[0042] S1. Crystal bead fluidization: 1) The sewage enters the water distribution area from the water inlet of the crystal bead fluidized tower and enters the water distribution area evenly through the water distribution pipe. The rising velocity of the water flow is 100m / h. At the same time, FeCl3 solution is added to the reagent dosing pipe as a precipitant and also enters the crystal bead fluidized area. NaOH is also added to adjust the pH value. Under the action of gas lift, the sewage contacts the precipitant, and the precipitant and F in the sewage are - Reaction to form small particles of precipitation; 2) The generated small particle precipitation combines with the quartz sand seed with a particle size of 0.1-0.3mm to begin to form the prototype of crystal beads. Through the continuous entry of raw water and gas, the formed prototype crystal beads are suspended in the crystal bead fluidization zone, and then continuously contact and wrap with the newly formed small particle precipitation, and continuously fluidize and circulate in the crystal bead fluidization zone to finally form mature crystal beads; 3) The mature crystal beads are precipitated and gathered at the bottom of the crystal bead fluidized bed tower and discharged from the crystal bead collection port; the wastewater after the reaction passes through the clarification area and is discharged from the outlet; the outlet of the crystal bead fluidized bed tower is equipped with a pH meter, which is interlocked with the addition of NaOH to control the pH value at 3-5, and is controlled and adjusted through the PLC interlock. S2. Secondary separation a) The water discharged from the outlet of the crystal bead fluidized bed tower is mixed with potassium aluminate coagulant to form a small floc mixture; b) The small flocs mixture enters the high-efficiency separation tower, and the water flow rises at a velocity of 40 m / h. Under the action of air lift, it contacts the flocculant, and the small flocs gradually become larger. Under the action of air lift, they circulate and fluidize until the large flocs are large enough to settle to the bottom of the high-efficiency separation tower. c) The large flocs are discharged from the sludge outlet at the bottom of the high-efficiency separation tower, and then mixed with sewage and enter the crystal bead fluidized bed tower again.

[0043] Embodiment 11 Different from Example 10, in Example 11, the quartz sand is modified by the method of Preparation Example 2 to obtain the composite modified seed crystal to replace the quartz sand.

[0044] Performance Testing The effluent quality in Examples 10-11 was tested, and the results are shown in Table 4.

[0045] Table 4 Water quality of the effluent from Example 11-11

[0046] Combining Examples 10-11 with Table 4, it can be seen that the treatment process of the present application has a good effect on the treatment of PO4 3- It also has excellent treatment effect on sewage.

[0047] Example 12 A crystal bead fluidized bed reaction sewage treatment process comprises the following steps: The sewage is gasification ash water project and the hardness in the water needs to be removed. The specific water quality is shown in Table 5.

[0048] Table 5 Gasification ash water quality table

[0049] S1. Crystal bead fluidization: 1) Sewage enters the water distribution area from the water inlet of the crystal bead fluidized tower and enters the crystal bead fluidized area evenly through the water distribution pipe. The rising velocity of the water flow is 100m / h. At the same time, NaOH solution is added to the reagent dosing pipe as a precipitant and also enters the crystal bead fluidized area. Under the action of gas lift, the sewage contacts the precipitant, and the precipitant and F in the sewage are - Reaction to form small particles of precipitation; 2) The generated small particle precipitation combines with the quartz sand seed with a particle size of 0.1-0.3mm to begin to form the prototype of crystal beads. Through the continuous entry of raw water and gas, the formed prototype crystal beads are suspended in the crystal bead fluidization zone, and then continuously contact and wrap with the newly formed small particle precipitation, and continuously fluidize and circulate in the crystal bead fluidization zone to finally form mature crystal beads; 3) The mature crystal beads are precipitated and gathered at the bottom of the crystal bead fluidized bed tower and discharged from the crystal bead collection port; the wastewater after the reaction passes through the clarification area and is discharged from the outlet; the outlet of the crystal bead fluidized bed tower is equipped with a pH meter, which is interlocked with the addition of NaOH to control the pH value at 9.5-10.3, and is controlled and adjusted through the PLC interlock; S2. Secondary separation a) The water discharged from the outlet of the crystal bead fluidized bed tower is mixed with potassium aluminate coagulant to form a small floc mixture; b) The small flocs mixture enters the high-efficiency separation tower, and the water flow rises at a velocity of 40 m / h. Under the action of air lift, it contacts the flocculant, and the small flocs gradually become larger. Under the action of air lift, they circulate and fluidize until the large flocs are large enough to settle to the bottom of the high-efficiency separation tower. c) The large flocs are discharged from the sludge outlet at the bottom of the high-efficiency separation tower, and then mixed with sewage and enter the crystal bead fluidized bed tower again.

[0050] Embodiment 13 Different from Example 12, in Example 13, the quartz sand is modified by the composite modified seed crystal obtained by modifying the quartz sand using the method of Preparation Example 2 to replace the quartz sand.

[0051] Performance Testing The effluent quality in Examples 12-13 was tested, and the results are shown in Table 6.

[0052] Table 6 Water quality of the effluent from Example 12-13

[0053] It can be seen from Examples 12-13 and Table 6 that the treatment process of the present application also has an excellent treatment effect on removing hardness from sewage.

[0054] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A crystal bead fluidized bed reaction wastewater treatment process, characterized in that: The following steps are involved: S1. Crystal bead fluidization: 1) The sewage enters the crystal bead fluidized bed tower and contacts with the precipitant in the crystal bead fluidized bed area under the action of gas lift. The precipitant reacts with the pollutants in the sewage to form small particle precipitation; 2) The generated small particle precipitation combines with the crystal seed to begin to form the prototype of the crystal bead. Through the continuous entry of raw water and gas, the formed prototype crystal bead is suspended in the crystal bead fluidization zone, and then continuously contacts and wraps with the newly formed small particle precipitation, and continuously fluidizes and circulates in the crystal bead fluidization zone to finally form mature crystal beads; 3) The mature crystal beads are precipitated and gathered at the bottom of the crystal bead fluidized bed tower and discharged from the crystal bead collection port; the wastewater after the reaction passes through the clarification area and is discharged from the outlet; S2. Secondary separation a) The water discharged from the outlet of the crystal bead fluidized bed tower is mixed with the coagulant to form a small floc mixture; b) The small flocs mixture enters the high-efficiency separation tower and contacts with the flocculant under the action of air lift. The small flocs gradually become larger and circulate and fluidize under the action of air lift until the large flocs are large enough to settle to the bottom of the high-efficiency separation tower. c) The large flocs are discharged from the mud outlet at the bottom of the high-efficiency separation tower, and then mixed with sewage and enter the crystal bead fluidized bed tower again.

2. A crystal bead fluidized bed reaction wastewater treatment process according to claim 1, characterized in that: The rising velocity of the water flow in the crystal bead fluidized tower is 60-100 m / h, and the rising velocity of the water flow in the high-efficiency separation tower is 20-60 m / h.

3. A crystal bead fluidized bed reaction wastewater treatment process according to claim 2, characterized in that: The rising velocity of the water flow in the crystal bead fluidized tower is 80-100 m / h.

4. A crystal bead fluidized bed reaction wastewater treatment process according to claim 1, characterized in that: The seed crystal is at least one of quartz sand or garnet.

5. A crystal bead fluidized bed reaction wastewater treatment process according to claim 5, characterized in that: The particle size of the seed crystal is 0.1-0.3 mm.

6. A crystal bead fluidized bed reaction wastewater treatment process according to claim 4, characterized in that: The seed crystal is a composite modified seed crystal, and the modification method thereof is as follows: i) mixing sodium hypochlorite and glacial acetic acid to obtain a mixed solution, using the mixed solution to oxidize seed crystals, soaking the oxidized seed crystals in a urea solution, reacting at 60-65° C. for 2 hours, and then filtering, washing, and drying to obtain amino-seed crystals; ii) dissolving and mixing calcium chloride and aluminum chloride to obtain a modified solution, adjusting the pH value of the modified solution to 10, adding amino-seed crystals to the modified solution, oscillating and reacting at 60-65° C. for 3 hours, and then filtering, drying, washing, and drying to obtain composite modified seed crystals.

7. A crystal bead fluidized bed reaction wastewater treatment process according to claim 6, characterized in that: The weight ratio of calcium chloride to aluminum chloride is (2-4):

1.

8. A crystal bead fluidized bed reaction wastewater treatment process according to claim 6, characterized in that: The concentration of the urea solution is 2-3 mol / L.

9. A crystal bead fluidized bed reaction wastewater treatment process according to claim 1, characterized in that: Different precipitants are selected according to the different pollutants in the sewage. When the sewage needs to be de-hardened, the precipitant is NaOH solution; when the sewage needs to be de-F - When the precipitant is calcium salt solution; the sewage needs to remove PO4 3- When the precipitant is an iron salt solution.

10. A crystal bead fluidized bed reaction wastewater treatment process according to claim 9, characterized in that: When the sewage needs to be de-hardened, the pH value of the effluent from the crystal bead fluidized bed tower is 9.5-10.3; - When the pH value of the effluent from the crystal bead fluidized bed tower is 8.5-9.0, the wastewater needs to be de-PO4 3- At this time, the pH value of the effluent from the crystal bead fluidized bed tower is 3-5.

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