CN116835728A - Water purifying device in sewage treatment - Google Patents

Abstract

The invention discloses a water purification device in sewage treatment, which includes a first stirring tank, a secondary flocculation tank, a second stirring tank and a centrifugal separation tank. The liquid inlet end of the first stirring tank is connected to a main pipeline and a magnetic powder liquid adding tank. Injection port, a stirrer is installed in the pool, and the stirrer is connected to the first motor; the secondary flocculation tank is connected to the liquid outlet of the first stirring tank, and the bottom is connected to a device for discharging the flocculated turbid water deposited in the secondary flocculation tank. Auxiliary pipeline; the liquid inlet end of the second mixing tank is connected to the auxiliary pipeline, and a stirrer is installed in the tank, and the stirrer is connected to the second motor; the centrifugal separation tank includes multiple centrifuges, and each centrifugal separator has liquid inlet The centrifugal separator is used to separate and recover the magnetic powder from the flocculated turbid water. The water purification device in sewage treatment provided by the present invention can realize the recycling and reuse of magnetic powder after sewage treatment, and reduces the processing cost and technical threshold of removing pollutants by magnetic flocculation technology.

Description

Water purification device in sewage treatment

Technical field

The invention belongs to the technical field of sewage treatment, and in particular relates to a water purification device in sewage treatment.

Background technique

In the production processes of papermaking, petrochemical, food, printing and dyeing, coal mining, metallurgy and mining industries, a certain amount of sewage and sludge will be produced. Direct discharge of these sewage and sludge will cause serious damage to the environment, so they need to be treated accordingly to reduce environmental pollution.

There are already precedents for using magnetic flocculation technology to remove medium pollutants in the existing technology. For example, Chinese invention patent CN103058447B proposes an integrated device for separation and purification of oily sewage sludge, including an oily sewage sludge separation device and a trace oil-water separator. When used, the trace oil-water separator performs pre-oil removal, and then the sludge and sewage react with the corresponding drugs (containing ferromagnetic powder) in the reactor to form a flocculated sediment, which is then discharged to the magnetic mud-water separator. In the separator box, the sediment is adsorbed on the disk and comes out of the water. The patent also records that the device has a high sediment extraction rate and efficiency, achieving good water treatment effects. The discharged water can reach the national A1 level standard, and the solid content of the sediment extracted is ≥35%. . However, how to recover and recycle the used magnetic powder has not been fully considered, and there is considerable room for improvement.

The present invention intends to propose a water purification device in sewage treatment to solve or partially solve the problem of recovery and recycling of magnetic powder in sewage treatment.

Contents of the invention

In order to solve the above technical problems, the present invention proposes a water purification device in sewage treatment, aiming to solve or improve at least one of the above technical problems.

In order to achieve the above object, the present invention provides a water purification device in sewage treatment, including:

A first stirring tank, the liquid inlet end of the first stirring tank is connected to the main pipe and the magnetic powder liquid filling port, the first stirring tank is equipped with a stirrer, and the stirrer is connected to the first motor;

Secondary flocculation tank, the secondary flocculation tank is connected with the liquid outlet end of the first stirring tank, and the bottom of the secondary flocculation tank is connected with a secondary pipe for discharging the flocculated turbid water deposited in the secondary flocculation tank. road;

a second stirring tank, the liquid inlet end of the second stirring tank is connected to the auxiliary pipeline, the second stirring tank is equipped with a stirrer, and the stirrer is connected to the second motor;

Centrifugal separation tank, the centrifugal separation tank includes a plurality of centrifugal separators, the liquid inlet end of each centrifugal separator is connected to the liquid outlet end of the second stirring tank; the centrifugal separator is used to remove the flocculated turbid water from the water. The magnetic particles are separated and recycled.

Optionally, the above-mentioned centrifugal separator includes a main housing, a centrifugal shaft rotatably connected to the central axis of the main housing, and a centrifugal disk located in the main housing, and the centrifugal disk is concentric and coaxial with the centrifugal shaft. It is arranged with a gap between the main housing and the centrifugal shaft, forming a first channel between the main housing and the centrifugal disk, and between the centrifugal disk and the centrifugal shaft. The second channel; the upper half of the centrifugal shaft is hollow to form a liquid inlet channel. The beginning of the liquid inlet channel is connected to the second stirring tank through the auxiliary pipeline, and the end of the liquid inlet channel is opened along its circumferential direction. There are several water nozzles penetrating the centrifugal shaft; a third motor is drivingly connected to the bottom of the centrifugal shaft.

Optionally, the above-mentioned centrifugal disk has several turns of electromagnetic coils spirally arranged around its center, and the electromagnetic coils are electrically connected to an external power supply.

Optionally, an adjustable current switch is provided between the electromagnetic coil and the power supply.

Optionally, a first valve is provided on the auxiliary pipeline near the liquid inlet channel; the auxiliary pipeline between the liquid inlet channel and the first valve is connected with a clean water inlet pipeline, and the The clean water inlet pipeline is provided with a second valve.

Optionally, the water purification device in sewage treatment also includes an evolved reservoir, and the purified water inlet pipeline connects the evolved reservoir and the liquid inlet channel.

Optionally, the liquid outlet end of the above-mentioned secondary flocculation tank is also connected to a third-stage membrane purification tank, and the liquid outlet end of the third-stage membrane purification tank is connected to the evolved reservoir. Includes several ceramic filter membranes.

Optionally, the above-mentioned second channel is connected to a magnetic powder liquid discharge pipe. The end of the magnetic powder liquid discharge pipe is connected to a magnetic powder liquid recovery pool. The magnetic powder liquid recovery pool is connected to the first stirring pool through a magnetic powder liquid circulation pipe. Realize the recycling of magnetic powder liquid.

Optionally, the above-mentioned water purification device in sewage treatment also includes a first-level filter tank. The first-level filter tank is provided with a bottom filter screen spaced a certain distance from the bottom of the tank. The bottom filter screen includes pores that allow sediment to pass through. , activated carbon and sandstone are filled above the bottom filter.

Optionally, the first-level filter tank is also provided with an intermediate partition plate vertically supported on the bottom filter. The intermediate partition plate divides the first-level filter tank into two, so that the first-level filter tank is The liquid inlet end and the liquid outlet end are respectively located on both sides of the middle partition.

Compared with the existing technology, the water purification device in sewage treatment provided by the present invention can recycle and reuse magnetic powder through a set of magnetic powder recovery and treatment systems installed after the secondary flocculation tank. The magnetic powder recovery and treatment system includes a second stirring tank, a centrifugal separation tank and a magnetic powder liquid recovery tank. By stirring the precipitate containing flocs twice and using centrifugal separation, the magnetic powder is quickly separated from the turbid water. After a simple The treatment can be recycled, so that the technology of magnetic flocculation technology to remove pollutants can be applied in actual production, reducing the processing cost and technical threshold of magnetic flocculation technology to remove pollutants.

Description of the drawings

The drawings that form a part of this application are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an improper limitation of this application. In the attached picture:

Figure 1 is a schematic structural diagram of a water purification device in sewage treatment provided by an embodiment of the present invention;

Figure 2 is a cross-sectional view of a centrifugal separator in an embodiment of the present invention;

Figure 3 is a schematic structural diagram of the electromagnetic coil in the centrifugal separator according to the embodiment of the present invention;

Figure 4 is an enlarged view of position A in Figure 2;

Figure 5 is a schematic structural diagram of the primary filter tank in the embodiment of the present invention.

In the picture:

1. Primary filter tank; 2. First stirring tank; 3. Secondary flocculation tank; 4. Third-stage membrane purification tank; 5. Reservoir after purification; 6. Second stirring tank; 7. Centrifugal separation tank; 8. Magnetic powder liquid recovery pool; 11. Pool A; 12. Pool B; 13. Pool C; 14. Middle partition; 15. Bottom filter;

101. Water inlet; 102. Magnetic powder liquid filling port; 103. Water outlet; 104. First sewage outlet; 105. Second sewage outlet;

201. Main pipeline; 202. Auxiliary pipeline; 203. Turbid liquid discharge pipe; 204. Magnetic powder liquid discharge pipe; 205. Magnetic powder liquid circulation pipe;

301. First motor; 302. Second motor; 303. Third motor; 304. Circulation pump; 305. Sewage pump;

401. The first valve; 402. The second valve;

70. Centrifugal separator; 71. Main shell; 72. Centrifugal disc; 73. Centrifugal shaft; 74. Bearing; 75. Bearing sealing cover; 76. Electromagnetic coil; 77. Power supply; 78. Adjustable current switch; 79. Wire; 701, first channel; 702, second channel; 703, centrifugal separation chamber; 730, liquid inlet channel; 731, water spray nozzle.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

In order to make the above objects, features and advantages of the present invention more obvious and understandable, the present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments.

The water purification device in sewage treatment of the present invention will be described below with reference to FIGS. 1 to 5 .

Referring to Figure 1, the water purification device in sewage treatment according to the embodiment of the present invention includes: a first-level filter tank 1, a first stirring tank 2, a second-level flocculation tank 3, a third-level membrane purification tank 4, which are connected in sequence through a main pipeline 201. The purified reservoir 5, as well as the secondary flocculation tank 3, the second mixing tank 6 and the centrifugal separation tank 7 connected through the auxiliary pipeline 202; the primary filter tank 1 is connected to the water inlet 101, and the purified reservoir 5 is connected to the outlet. Water inlet 103, main pipeline 201 connects water inlet 101, each purification pool group (first-level filter pool 1, first mixing pool 2, second-level flocculation pool 3, third-level membrane purification pool 4, purified storage pool 5) and Water outlet 103; the secondary flocculation tank 3 is also connected to a secondary pipeline 202 at the bottom, through which the flocculated sediment is introduced into the second stirring tank 6, and then the stirring liquid is sent to the centrifugal separation tank 7, and centrifuged A centrifugal separator 70 is provided in the separation tank 7. The centrifugal separator 70 has a turbid liquid discharge pipe 203 and a magnetic powder liquid discharge pipe 204. The turbid liquid discharge pipe 203 is connected to the first sewage outlet 104, and the magnetic powder liquid discharge pipe 204 is connected to the magnetic powder liquid. Recycling pool 8.

Specifically, the primary filter tank 1, the first mixing tank 2, the secondary flocculation tank 3, the third-stage membrane purification tank 4, and the purified reservoir 5 form the main purification tank group, which are connected in sequence through the main pipeline 201. The sewage enters the first-level filter tank 1 from the water inlet 101. The first-level filter tank 1 is filled with activated carbon and sandstone. After primary sedimentation, large particle impurities and odors in the water are removed; it enters the first mixing tank 2, and A stirring tank 2 is connected to the magnetic powder liquid filling port 102 and has a built-in stirrer. The stirrer is driven and rotated by the first motor 301 on the top of the tank. The sewage is fully mixed with the magnetic powder liquid in the first stirring tank 2 and then enters the secondary flocculation. In Pool 3, the secondary flocculation pool 3 is a static sedimentation tank. The sewage mixed with magnetic powder liquid is statically sedimented in the secondary flocculation pool 3. The magnetic powder liquid contains heavy medium magnetic powder and flocculant. The magnetic powder has a good effect on impurities in the water. The adsorption effect can penetrate into the floc and strengthen the network structure of the floc, quickly achieving the effect of solid-liquid separation. The separated supernatant enters the third-stage membrane purification tank 4 through the main pipeline 201, and the precipitated floc is Pumped to the auxiliary pipeline 202, it enters the second mixing tank 6; the water after entering the three-stage membrane purification tank 4 enters the membrane purification treatment stage. The three-stage membrane purification tank 4 includes a number of ceramic filter membranes, which have a microporous structure and can To filter out impurities and microorganisms in the water, the ceramic filter membrane uses a pore size between 0.1 and 0.5 μm. It can filter out bacteria, viruses, and suspended solids in the water while retaining nutrients and minerals in the water. You can choose from the ones on the market. MBR membranes on sale; the water quality after membrane purification has reached drinking water standards and enters the purified reservoir 5.

Specifically, the second stirring tank 6, the centrifugal separation tank 7 and the magnetic powder liquid recovery tank 8 form a recovery and treatment tank group for magnetic powder liquid recovery, which are connected through the auxiliary pipeline 202; the second stirring tank 6 has a stirrer, and the stirrer passes through The second motor 302 at the top of the tank drives and rotates, and the precipitated floc is stirred in the second stirring tank 6 to separate the magnetic powder and impurities, turn it into turbid water again, and send it to the centrifugal separation tank through the auxiliary pipeline 202 7, the centrifugal separation tank 7 includes a plurality of centrifuges 70. Under the action of centrifugal force and magnetic attraction force of the centrifugal separators 70, the magnetic powder and the turbid water containing impurities are separated, and the turbid water containing impurities passes through the turbid liquid. The magnetic powder is discharged from the discharge pipe 203, and the magnetic powder is flushed into the magnetic powder liquid discharge pipe 204 through clean water, and enters the magnetic powder liquid recovery tank 8.

Further, as shown in Figure 2, the structure of the centrifugal separator 70 is to include a main housing 71, a centrifugal separation chamber 703 is formed in the main housing 71, and a centrifugal shaft 73 is provided up and down in the middle of the centrifugal separation chamber 703. The shaft 73 is driven to rotate at high speed by an external third motor 303; as shown in Figure 4, the upper half of the centrifugal shaft 73 is hollow to form a liquid inlet channel 730. The top of the liquid inlet channel 730 is connected to the auxiliary pipeline 202, and the bottom end is opened along its circumferential direction. There is a water spray nozzle 731 that penetrates to the outside of the centrifugal shaft 73. While the centrifugal shaft 73 rotates at high speed, the water spray nozzle 731 sprays turbid water outwards. The turbid water performs centrifugal motion under the force of high-speed rotation; in order to separate the centrifugally separated The magnetic powder is isolated from the turbid water. A funnel-shaped centrifugal disk 72 is provided at the bottom of the centrifugal separation chamber 703. The centrifugal disk 72 and the centrifugal shaft 73 are coaxially arranged. There is a gap between the bottom of the centrifugal disk 72 and the centrifugal shaft 73 to form a liquid supply. There is also a gap between the second outflow channel 702 and the centrifugal disk 72 and the main housing 71 to form a first channel 701 for liquid to flow out. The first channel 701 and the second channel 702 are isolated from each other, and the first channel is connected to the turbidity The liquid discharge pipe 203 and the second channel 702 are connected to the magnetic powder liquid discharge pipe 204. The end of the turbid liquid discharge pipe 203 has a first drain port 104.

Further, bearings 74 are provided at positions where the upper and lower ends of the centrifugal shaft 73 are rotatably connected to the main housing 71 , and sealing pads are provided up and down the bearings 74 at the position where the upper end of the centrifugal shaft 73 is connected to the auxiliary pipeline 202 , and seals are provided on the bearings. 74 upper gland has bearing seal cover 75.

Further, as shown in Figures 2 and 3, electromagnetic coils 76 are arranged spirally upward along the circumferential direction in the centrifugal disk 72 to provide a magnetic field force for adsorbing magnetic powder. Under the dual effects of the gravity field and the magnetic field, the magnetic powder is rapidly separated. The electromagnetic coil 76 is connected to a power supply 77 and an adjustable current switch 78 through a wire 79. By changing the current of the electromagnetic coil 76, the magnetic field force can be adjusted.

Further, the auxiliary pipeline 202 between the second mixing tank 6 and the centrifugal separator 70 is provided with a first valve 401, and the liquid inlet end of the centrifugal separator 70 is also connected to the purified reservoir 5. At the same time, in this A second valve 402 is provided on the pipeline section. When the first valve 401 is opened, the second valve 402 is closed, the centrifuge 70 is in working condition, and the turbid water is input from the second mixing tank 6 to the centrifuge 70. When the centrifugal separation After the machine has been working for a period of time, more magnetic powder has accumulated at the bottom. At this time, the first valve 401 is closed, the second valve 402 is opened, and clean water is used to flush the magnetic powder into the magnetic powder liquid recovery pool 8. Since the first valve 401 and the The section from the second valve 402 to the centrifuge 70 shares a section of pipeline. When the first valve 401 is closed, a certain amount of turbid water still remains in the pipeline. Therefore, after the second valve 402 is opened, the centrifuge 70 still needs to be opened for a period of time. After the remaining turbid water is separated, the electromagnetic supply is stopped and the magnetic particles are recovered.

Further, the magnetic powder liquid recovery pool 8 is connected to the first stirring pool 2 through a magnetic powder liquid circulation pipe 205. A circulation pump 304 is provided on the magnetic powder liquid circulation pipe 205, which can be turned on intermittently as needed to control the magnetic powder liquid recovery pool 8. Magnetic powder liquid is recycled.

Further, as shown in Figure 5, the primary filter tank 1 includes pools A, B, and C. The upper half of pool A 11 and pool B 12 are separated by an intermediate partition 114 to allow sewage and filtered supernatant to pass through. The liquid can be effectively isolated; there is a certain height from the bottom of the middle partition 14 to the bottom of the pool, and a bottom filter 15 is provided. The bottom filter 15 supports and drags up the activated carbon and sandstone in the upper A pool 11 and B pool 12. The bottom filter The net 15 has larger pores, so that the sediments in the sewage can fall into the C pool 13 located under the bottom filter 15 through the pores; the upper half of the middle partition 14 is a solid plate, and the lower half is a mesh plate. , the upper half of the solid plate can effectively isolate the anhydrous liquid before filtration and the filtered supernatant, and the lower half of the mesh plate allows the filtered water to pass through; C pool 13 is connected to a sewage pump 305, and the sewage pump 305 extracts the sediment slurry and then passes through The second sewage outlet 105 is discharged, and after simple dehydration, a mud cake is formed for other recycling processes.

The operating principle of the embodiment of the present invention:

The sewage enters the first-level filter tank 1 through the water inlet 101. After preliminary precipitation, the adsorption of first-level activated carbon and sandstone removes large particle impurities and algae in the water, and reagents for removing nitrogen and phosphorus are added as needed, so that the first-level filtered The solution becomes supernatant, and the supernatant enters the first stirring tank 2; magnetic powder liquid containing magnetic powder is added to the first stirring tank 2 through the magnetic powder liquid filling port. After stirring, the magnetic powder liquid and the supernatant are fully mixed and then enter to the secondary flocculation tank 3; the supernatant after adding the magnetic powder liquid is statically precipitated in the secondary flocculation tank 3. The magnetic powder liquid contains heavy medium magnetic powder and flocculant. The magnetic powder has a good adsorption effect on impurities in the water. It can penetrate into the floc and strengthen the network structure of the floc, quickly achieving the effect of solid-liquid separation. The separated supernatant enters the third-stage membrane purification tank 4 through the main pipeline 201, and the precipitated floc is pumped to the auxiliary pipe Road 202, enters the second mixing tank 6; the supernatant after entering the third-stage membrane purification tank 4, under the action of the ceramic filter membrane, filters out bacteria, viruses, and suspended solids in the water, while retaining nutrients in the water. ingredients and minerals. At this point, purified purified water is obtained, and the purified water is centrally stored in the purified reservoir 5 .

The filtered water containing flocs that enters the second stirring tank 6 through the auxiliary pipeline 202 is driven and stirred by the second motor 302, and the magnetic powder is separated from the particulate matter and impurities, and becomes turbid water again, and the turbid water is sent The magnetic powder and impurities are separated in the centrifugal separation tank 7. The turbid water passes through multiple branch pipes and enters multiple centrifuges 70. Under the action of the gravity field, the magnetic powder and impurity liquid are separated, in order to further improve the separation effect. , an electromagnetic coil 76 is provided in the centrifugal disk 72 to provide an electromagnetic field for adsorbing magnetic powder. The electromagnetic coil 76 provides current through the power supply 77 and adjusts the power supply current through the adjustable current switch 78 to adjust the size of the electromagnetic field. When the centrifugal disk 72 After absorbing more magnetic powder, close the first valve 401, open the second valve 402, rinse the liquid inlet channel 730 with clean water, turn off the adjustable current switch 78, the electromagnetic coil 76 stops energizing, the magnetic field disappears, and at the same time the third motor 303 The rotation speed is reduced, clean water is flushed downward along the centrifugal disk 72, and the magnetic powder is flushed into the second channel 702, and then collected into the magnetic powder liquid recovery pool 8 through the magnetic powder liquid discharge pipe 204.

The technical effects of the water purification device in sewage treatment according to the embodiment of the present invention are detailed in the content of the invention and will not be described again here.

In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", The orientations or positional relationships indicated by "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present invention, rather than indicating or It is implied that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation and is therefore not to be construed as a limitation of the invention.

The above-described embodiments only describe the preferred modes of the present invention and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, those of ordinary skill in the art can make various modifications to the technical solutions of the present invention. All deformations and improvements shall fall within the protection scope determined by the claims of the present invention.

Claims (10)

1. A water purification apparatus in sewage treatment, comprising:

the magnetic powder stirring device comprises a first stirring tank (2), wherein a liquid inlet end of the first stirring tank (2) is connected with a main pipeline (201) and a magnetic powder liquid filling port (102), a stirrer is arranged in the first stirring tank (2), and the stirrer is connected with a first motor (301);

the secondary flocculation tank (3), the secondary flocculation tank (3) is communicated with the liquid outlet end of the first stirring tank (2), and the bottom of the secondary flocculation tank (3) is connected with a secondary pipeline (202) for discharging flocculated turbid water deposited in the secondary flocculation tank (3);

the liquid inlet end of the second stirring tank (6) is connected with the auxiliary pipeline (202), a stirrer is arranged in the second stirring tank (6), and the stirrer is connected with a second motor (302);

a centrifugal separation tank (7), wherein the centrifugal separation tank (7) comprises a plurality of centrifugal separators (70), and the liquid inlet end of each centrifugal separator (70) is connected with the liquid outlet end of the second stirring tank (6); the centrifuge (70) is used for separating magnetic powder from the flocculated turbid water and recovering the magnetic powder.

2. A water purification device in sewage treatment according to claim 1, wherein the centrifuge (70) comprises a main housing (71), a centrifugal shaft (73) rotatably connected to the central axis of the main housing (71), a centrifugal disc (72) located in the main housing (71), the centrifugal disc (72) being arranged concentrically and coaxially with the centrifugal shaft (73) and being spaced from both the main housing (71) and the centrifugal shaft (73), forming a first channel (701) between the main housing (71) and the centrifugal disc (72), and a second channel (702) between the centrifugal disc (72) and the centrifugal shaft (73); the inside of the upper half section of the centrifugal shaft (73) is hollow to form a liquid inlet channel (730), the initial end of the liquid inlet channel (730) is connected to the second stirring pool (6) through the auxiliary pipeline (202), and the tail end of the liquid inlet channel (730) is provided with a plurality of water spray nozzles (731) penetrating through the centrifugal shaft (73) along the circumferential direction of the liquid inlet channel; the bottom of the centrifugal shaft (73) is in driving connection with a third motor (303).

3. A water purification device in sewage treatment according to claim 2, characterized in that the centrifugal disc (72) is arranged with several turns of electromagnetic coils (76) around its centre, which electromagnetic coils (76) are electrically connected to an external power source (77).

4. A water purification apparatus in sewage treatment according to claim 3, characterized in that an adjustable current switch (78) is provided between the electromagnetic coil (76) and the power source (77).

5. A water purification device in sewage treatment according to claim 2, wherein a first valve (401) is provided on the secondary line (202) in the vicinity of the feed channel (730); the auxiliary pipeline (202) between the liquid inlet channel (730) and the first valve (401) is communicated with a water purifying inlet pipeline, and a second valve (402) is arranged on the water purifying inlet pipeline.

6. The water purification device in wastewater treatment according to claim 5, further comprising a post-evolution reservoir (5), said purified water inlet line communicating said post-evolution reservoir (5) with said feed channel (730).

7. The water purification device in sewage treatment according to claim 6, wherein the liquid outlet end of the secondary flocculation tank (3) is further connected with a tertiary membrane purification tank (4), the liquid outlet end of the tertiary membrane purification tank (4) is communicated to the post-evolution reservoir (5), and a plurality of ceramic filtering membranes are included in the tertiary membrane purification tank (4).

8. The water purification device in sewage treatment according to claim 2, wherein the second channel (702) is communicated to a magnetic powder liquid discharge pipe (204), a magnetic powder liquid recovery tank (8) is connected to the end of the magnetic powder liquid discharge pipe (204), and the magnetic powder liquid recovery tank (8) is communicated to the first stirring tank (2) through a magnetic powder liquid circulation pipe (205) to realize magnetic powder liquid recycling.

9. The water purification device in sewage treatment according to any one of claims 1 to 8, further comprising a primary filter tank (1), wherein a bottom filter screen (15) is provided in the primary filter tank (1) at a distance from the tank bottom, the bottom filter screen (15) comprises pores allowing sediment to pass through, and activated carbon and quartz sand are filled above the bottom filter screen (15).

10. The water purification device in sewage treatment according to claim 9, wherein an intermediate baffle (14) vertically supported on the bottom filter screen (15) is further provided in the primary filter tank (1), and the intermediate baffle (14) divides the primary filter tank (1) into two parts, so that the liquid inlet end and the liquid outlet end of the primary filter tank (1) are respectively positioned at two sides of the intermediate baffle (14).