A multi-stage separation pretreatment device for wastewater

Abstract

The present invention discloses a multi-stage separation pretreatment device for wastewater, which comprises a box body; a drainage area is communicated with a flotation tank through a wastewater flow-through pipe, and an air diffuser pipe is arranged near the wastewater flow-through pipe in the flotation tank; a scum scraper is installed on the top surface of the flotation tank; the bottom of a secondary flocculation tank is communicated with an inclined tube sedimentation tank, and the top of the inclined tube sedimentation tank is communicated with a water production tank. Advantages: The present invention performs primary treatment on wastewater through a primary flocculation tank to flocculate suspended substances in the wastewater, and the scum scraper in the flotation tank skims the scum into a scum collection hopper; the air bubbles in the wastewater are eliminated through a defoaming tank, and then the pollutants that are not easily flotated in the wastewater are flocculated through a coagulation tank and a secondary flocculation tank in sequence; finally, the sludge in the water is precipitated through an inclined tube sedimentation tank; through continuous multi-stage treatment of wastewater by the present invention, the treatment efficiency is high, the effect is good, and the process requirements can be met; moreover, the overall structure is compact, the floor area is small, and the whole can be moved as a whole.

Description

Technical Field:

[0001] The present invention relates to the technical field of wastewater treatment, and particularly to a multi-stage separation pretreatment device for wastewater. Background Art:

[0002] In the treatment of industrial wastewater, traditionally, a flotation device is mainly used for solid-liquid separation. Pollutants suitable for flotation in the wastewater are flocculated into groups by adding chemicals and float to the water surface under the action of bubbles, and then are removed by a slag scraping device. However, pollutants in the wastewater that are not suitable for flotation cannot be removed by the flotation device, resulting in poor wastewater treatment effect.

[0003] Another treatment method for wastewater is to directly set inclined tube fillers in the existing flotation device, that is, the treatment of wastewater is completed by flotation and sedimentation in one pool. However, during the treatment process, some precipitates in the wastewater are affected by the bubbles generated during flotation and cannot settle to the bottom of the pool, resulting in poor sedimentation effect of some pollutants and poor wastewater treatment effect. In addition, currently, there is also a form of using a flotation device and a sedimentation device in series, which has a large overall volume, a large floor area, a high cost, and a poor treatment effect. Summary of the Invention:

[0004] The purpose of the present invention is to provide a multi-stage separation pretreatment device for wastewater with a compact structure, a small floor area, and a good treatment effect.

[0005] The present invention is implemented by the following technical solution: A multi-stage separation pretreatment device for wastewater, which includes a box body; the box body is divided into a primary flotation separation pool and a secondary flocculation sedimentation separation pool; the primary flotation separation pool includes a primary flocculation pool, a flotation pool, a defoaming pool, and a coagulation pool; the defoaming pool is divided into an intermediate water chamber and a defoaming chamber by a defoaming partition; the drainage area of the primary flocculation pool is connected to the flotation pool through a wastewater overflow pipe, and an aeration pipe is arranged near the wastewater overflow pipe in the flotation pool; a slag scraping machine is installed on the top surface of the flotation pool, and a scum collection hopper is fixed on the inner wall of the flotation pool adjacent to the defoaming pool; the flotation pool is connected to the intermediate water chamber through a wastewater flow pipe, and the defoaming chamber is connected to the bottom of the alkaline area of the coagulation pool; the secondary flocculation sedimentation separation pool includes a secondary flocculation pool, an inclined tube sedimentation tank, and a water production pool; the top of the coagulation sedimentation area of the coagulation pool is connected to the bottom of the central cylinder in the secondary flocculation pool through a pipeline, the bottom of the secondary flocculation pool is connected to the inclined tube sedimentation tank, and the top of the inclined tube sedimentation tank is connected to the water production pool.

[0006] Further, the primary flocculation tank is divided into a coagulation zone, the drainage zone, and a flocculation zone by a first partition and a second partition; the coagulation zone is provided with a wastewater inlet, the bottom of the coagulation zone is communicated with the flocculation zone through a pipeline, and the height of the second partition between the drainage zone and the flocculation zone is less than that of the first partition; primary flocculation mixers are installed in both the coagulation zone and the drainage zone.

[0007] Further, a gate valve is installed in the defoaming tank, and the plug plate of the gate valve is in sliding contact with the defoaming partition.

[0008] Further, the coagulation tank is divided into the alkaline zone, the hardness removal zone, and the coagulation sedimentation zone by a first baffle and a second baffle; the bottom of the hardness removal zone is communicated with the bottom of the coagulation sedimentation zone, and coagulation mixers are installed in the alkaline zone, the hardness removal zone, and the coagulation sedimentation zone.

[0009] Further, a partition plate is fixed in the dissolved air flotation tank between the wastewater overflow pipe and the slag scraper, and a guide plate bent towards the slag scraper is fixed at the top of the partition plate.

[0010] Further, a central cylinder with an open top is fixed in the secondary flocculation tank, and a secondary flocculation mixer is installed in the central cylinder.

[0011] Further, a baffle is fixed at one end of the inclined tube group of the inclined tube sedimentation tank adjacent to the secondary flocculation tank, and the inclined tube sedimentation tank is separated from the water production tank by an overflow weir plate.

[0012] Further, it further includes an air compressor, a dissolved air water pump, and a dissolved air tank; the defoaming chamber is communicated with the water inlet of the dissolved air water pump through a water inlet pipe, the water outlet of the dissolved air water pump is communicated with the water inlet of the dissolved air tank, the air compressor is communicated with the air inlet of the dissolved air tank through an air pipe, and the liquid outlet of the dissolved air tank is communicated with the aeration pipe.

[0013] Further, the bottom of the scum collection hopper and the bottom of the inclined tube sedimentation tank are respectively communicated with a sludge pipe.

[0014] Further, the primary flocculation tank, the dissolved air flotation tank, the defoaming tank, the coagulation tank, and the secondary flocculation tank are respectively communicated with an emptying pipe.

[0015] Advantages of the present invention: Compared with the prior art, the present invention is successively connected with a primary flocculation tank, a dissolved air flotation tank, a defoaming tank, a coagulation tank, a secondary flocculation tank, an inclined tube sedimentation tank, and a water production tank, and forms an organic whole through a certain positional relationship and connection relationship.

[0016] The wastewater is treated once in the primary flocculation tank to flocculate the suspended solids in the wastewater. The flocculated wastewater is introduced into the air flotation tank, and then the suspended solids are floated to the water surface by aeration. The scum scraper in the air flotation tank skims the scum into the scum collection hopper for easy cleaning. The defoaming tank can eliminate the bubbles in the wastewater, avoiding the influence of bubbles on the sedimentation of the precipitate in the subsequent process and effectively ensuring the sedimentation effect. Then, the pollutants that are not easily air-flotated in the wastewater are flocculated and treated in the coagulation tank and the secondary flocculation tank in sequence, facilitating the improvement of the sedimentation effect in the subsequent process. Finally, the sludge in the water is precipitated in the inclined tube sedimentation tank for easy treatment. Thus, through the continuous multi-stage treatment of wastewater by the present invention, the treatment efficiency is high, the effect is good, and the process requirements can be met; moreover, the overall structure is compact, the floor area is small, and the overall movement can be realized. BRIEF DESCRIPTION OF THE DRAWINGS:

[0017] Figure 1 It is a schematic structural diagram of the present invention.

[0018] Figure 2 It is Figure 1 the A-A cross-sectional view of

[0019] Figure 3 It is Figure 1 the B-B cross-sectional view of

[0020] Figure 4 It is a schematic three-dimensional structure of the present invention Figure 1 .

[0021] Figure 5 It is a schematic three-dimensional structure of the present invention Figure 2 .

[0022] The markings of each component in the drawings are as follows: box body 1, primary air flotation separation tank 2, primary flocculation tank 2.1, coagulation zone 2.1111, wastewater inlet 2.111, drainage zone 2.12, flocculation zone 2.13, first partition board 2.14, second partition board 2.15, primary flocculation agitator 2.16, air flotation tank 2.2, defoaming tank 2.3, intermediate water chamber 2.31, gate valve 2.32, defoaming chamber 2.33, defoaming partition board 2.34, coagulation tank 2.4, alkaline zone 2.41, hardness removal zone 2.42, coagulation sedimentation zone 2.43, first baffle 2.44, second baffle 2.45, coagulation agitator 2.46, wastewater flow-through pipe 2.5, aeration pipe 2.6, scum scraper 2.7, scum collection hopper 2.8, wastewater through-flow pipe 2.9, flow partition board 2.10, guide board 2.11, secondary flocculation sedimentation separation tank 3, secondary flocculation tank 3.1, central cylinder 3.11, secondary flocculation agitator 3.12, inclined tube sedimentation tank 3.2, baffle 3.21, overflow weir plate 3.22, inclined tube group 3.23, sedimentation tank 3.24, product water tank 3.3, air compressor 4, dissolved air water pump 5, dissolved air tank 6, inlet pipe 7, air pipe 8, sludge pipe 9, drain pipe 10. Detailed implementation manners:

[0023] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts shall fall within the protection scope of the present invention.

[0024] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "front", "rear", "top", "bottom", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0025] Such as Figures 1 to 5As shown in the figure, this embodiment provides a multi-stage separation pretreatment device for wastewater, which includes a box body; the box body 1 is divided into a primary air flotation separation tank 2 and a secondary flocculation sedimentation separation tank 3; the primary air flotation separation tank 2 includes a primary flocculation tank 2.1, an air flotation tank 2.2, a defoaming tank 2.3, and a coagulation tank 2.4 arranged in sequence; the primary flocculation tank 2.1 is divided into a coagulation area 2.1111, a drainage area 2.12, and a flocculation area 2.13 by a first partition plate 2.14 and a second partition plate 2.15. There is a first partition plate 2.14 between the coagulation area 2.1111 and the drainage area 2.12, and a second partition plate 2.15 between the drainage area 2.12 and the flocculation area 2.13; there is a wastewater inlet 2.111 at the upper part of the coagulation area 2.1111, and dosing ports are provided in both the coagulation area 2.1111 and the flocculation area 2.13; the bottom of the coagulation area 2.1111 is communicated with the flocculation area 2.13 through a pipeline, and the height of the second partition plate 2.15 is less than the height of the first partition plate 2.14; primary flocculation mixers 2.16 are installed in both the coagulation area 2.1111 and the drainage area 2.12; wastewater first enters the coagulation area 2.1111 of the primary flocculation tank 2.1 through the wastewater inlet 2.111, and a coagulant is added into the coagulation area 2.1111 through the dosing port. Under the action of the primary flocculation mixer 2.16, the suspended solids in the wastewater are fixed; the coagulated wastewater flows into the flocculation area 2.13 through a pipeline, and a flocculant is added into the flocculation area 2.13 through the dosing port to gather the suspended solids in the wastewater together. The flocculated wastewater flows into the middle drainage area 2.12 by flowing around the top edge of the second partition plate 2.15. Under the action of the primary flocculation mixer 2.16, the sludge after flocculation is prevented from settling in the drainage area 2.12, facilitating subsequent treatment processes; thus, the wastewater entering the primary flocculation tank 2.1 flows from the coagulation area 2.1111 into the flocculation area 2.13 and then flows around the second partition plate 2.15 into the drainage area 2.12, which is beneficial to extending the residence time of the wastewater, enabling the wastewater to be fully mixed with the medicament, and having a good flocculation effect.

[0026] The drainage area 2.12 of the primary flocculation tank 2.1 is connected to the air flotation tank 2.2 through the wastewater overflow pipe 2.5. The flocculated wastewater flows into the air flotation tank 2.2 from the wastewater overflow pipe 2.5. A scum scraper 2.7 is installed on the top surface of the air flotation tank 2.2, and a scum collection hopper 2.8 is fixed on the inner wall of one side of the air flotation tank 2.2 adjacent to the defoaming tank 2.3. A baffle plate 2.10 is vertically fixed in the air flotation tank 2.2 between the wastewater overflow pipe 2.5 and the scum scraper 2.7. The top end of the baffle plate 2.10 is fixed with a guide plate 2.11 bent towards the scum scraper 2.7. An air diffuser pipe 2.6 is arranged in the air flotation tank 2.2, and the outlet of the air diffuser pipe 2.6 is above the outlet of the wastewater overflow pipe 2.5. The residence time of the wastewater in the air flotation tank 2.2 is 10 - 20 minutes. The dissolved air water is introduced into the air flotation tank 2.2 through the air diffuser pipe 2.6 to one side of the baffle plate 2.10, so as to bring the suspended substances in the wastewater to the water surface through bubbles. The suspended substances in the wastewater flow towards the scum scraper 2.7 along the guide plate 2.11, and then the scum floating on the surface of the wastewater is skimmed into the scum collection hopper 2.8 by the scum scraper 2.7, separating part of the sludge in the wastewater, achieving the purpose of treating the wastewater, and the wastewater overflows to the other side of the baffle plate 2.10 along the guide plate 2.11.

[0027] It also includes an air compressor 4, a dissolved air water pump 5 and a dissolved air tank 6. The defoaming chamber 2.33 is connected to the inlet of the dissolved air water pump 5 through a water inlet pipe 7. The outlet of the dissolved air water pump 5 is connected to the inlet of the dissolved air tank 6. The air compressor 4 is connected to the inlet of the dissolved air tank 6 through an air pipe 8. The liquid outlet of the dissolved air tank 6 is connected to the inlet of the air diffuser pipe 2.6. In the present invention, part of the wastewater defoamed in the defoaming chamber 2.33 is introduced into the dissolved air water pump 5 through the water inlet pipe 7, and then sent into the dissolved air tank 6 by the dissolved air water pump 5, and is pressurized and dissolved through the air compressor 4. The dissolved air water in the dissolved air tank 6 is sent into the air flotation tank 2.2 through the air diffuser pipe 2.6. Under the action of the air compressor 4, compressed air is introduced into the dissolved air tank 6 to form bubbles. Part of the bubbles entering the air flotation tank 2.2 will float on the water surface. Since the pressure of the compressed air in the bubbles is greater than the atmospheric pressure, the floating bubbles will burst, and there are still some bubbles in the wastewater flowing into the next process.

[0028] The defoaming tank 2.3 is separated into an intermediate water chamber 2.31 and a defoaming chamber 2.33 by a defoaming partition plate 2.34; the air flotation tank 2.2 is communicated with the intermediate water chamber 2.31 through a wastewater flow pipe 2.9, and the wastewater in the air flotation tank 2.2 flows into the intermediate water chamber 2.31 through the wastewater flow pipe 2.9. A gate valve 2.32 is installed in the defoaming tank 2.3, and the insertion plate of the gate valve 2.32 is in sliding contact with the defoaming partition plate 2.34; the wastewater in the intermediate water chamber 2.31 overflows to the defoaming chamber 2.33 through the top surface of the gate valve 2.32. The defoaming tank 2.3 can adjust the water level of the intermediate water chamber 2.31 in real time through the gate valve 2.32, ensuring that the water in the intermediate water chamber 2.31 slowly flows into the defoaming chamber 2.33, which is beneficial to exposing more bubbles in the wastewater to the air; there is a water level difference between the water level in the intermediate water chamber 2.31 and the water level in the defoaming chamber 2.33. During the process of the wastewater in the intermediate water chamber 2.31 overflowing to the defoaming chamber 2.33, a small amount of bubbles in the wastewater will burst during the falling process, so as to achieve the purpose of removing the bubbles in the water through the overflow method, avoiding the bubbles from affecting the sedimentation of the sediment in the subsequent process at the bottom of the tank, and ensuring the sedimentation effect of the sludge in the subsequent process.

[0029] The coagulation tank 2.4 is separated into an alkaline area 2.41, a hardness removal area 2.42 and a coagulation sedimentation area 2.43 by a first baffle plate 2.44 and a second baffle plate 2.45; a first baffle plate 2.44 is arranged between the alkaline area 2.41 and the hardness removal area 2.42, and a second baffle plate 2.45 is arranged between the hardness removal area 2.42 and the coagulation sedimentation area 2.43; the defoaming chamber 2.33 is communicated with the bottom of the alkaline area 2.41, and the bottom of the hardness removal area 2.42 is communicated with the bottom of the coagulation sedimentation area 2.43; the defoamed wastewater first flows into the alkaline area 2.41; the alkaline area 2.41, the hardness removal area 2.42 and the coagulation sedimentation area 2.43 are all provided with chemical dosing ports and coagulation mixers 2.46. Liquid caustic agent is added into the alkaline area 2.41 through the chemical dosing port to adjust the pH value of the wastewater to 9 to 11.5, making the wastewater alkaline, which is beneficial to improving the subsequent effect of removing calcium ions, magnesium ions and aluminum ions; the wastewater after adjusting the pH value flows into the hardness removal area 2.42 from the top surface of the first baffle plate 2.44, and carbonate is added to the hardness removal area 2.42 to remove other pollutants such as calcium ions, magnesium ions and aluminum ions that can form precipitates. These pollutants are not easily treated by air flotation in the previous process and need to be treated by subsequent precipitation; the wastewater after hardness removal flows into the coagulation sedimentation area 2.43 from the bottom of the second baffle plate 2.45, and a coagulant is added to the coagulation sedimentation area 2.43 to aggregate the newly formed precipitates; during the above process, the wastewater forms a folded flow direction successively through the top surface of the first baffle plate 2.44 and the bottom of the second baffle plate 2.45, which is beneficial to extending the residence time of the wastewater, making the wastewater fully mixed with the chemical agent, and carried out under the stirring of the coagulation mixer 2.46, which is beneficial to making the wastewater fully mixed with the chemical agent, and at the same time avoiding the precipitation of the precipitate, facilitating centralized treatment in the subsequent process.

[0030] The secondary flocculation sedimentation separation tank 3 includes a secondary flocculation tank 3.1, an inclined tube sedimentation tank 3.2 and a water production tank 3.3; a chemical dosing port is provided in the water production tank 3.3 for dosing to adjust the pH value of the water quality to meet the process requirements; a central cylinder 3.11 with an open top is fixed in the secondary flocculation tank 3.1, a chemical dosing pipe is communicated in the central cylinder 3.11, and a secondary flocculation mixer 3.12 is installed in the central cylinder 3.11; the top of the coagulation sedimentation area 2.43 is communicated with the bottom of the central cylinder 3.11 in the secondary flocculation tank 3.1 through a pipeline; the wastewater treated by the coagulation tank 2.4 flows into the central cylinder 3.11 through a pipeline, and a flocculant is added into the central cylinder 3.11 through the chemical dosing pipe. Under the slow stirring of the secondary flocculation mixer 3.12, it is beneficial for the chemical agent to be fully mixed with the wastewater; the wastewater added with the chemical agent overflows from the top edge of the central cylinder 3.11 into the secondary flocculation tank 3.1, so that the remaining suspended substances in the wastewater are flocculated; the bottom of the secondary flocculation tank 3.1 is communicated with the inclined tube sedimentation tank 3.2, and the flocculated wastewater flows into the inclined tube sedimentation tank 3.2; the structure of the inclined tube sedimentation tank 3.2 is a prior art, including an inclined tube group 3.23 and a sedimentation tank 3.24 arranged up and down; a baffle 3.21 is fixed at one end of the inclined tube group 3.23 of the inclined tube sedimentation tank 3.2 adjacent to the secondary flocculation tank 3.1, the inclined tube sedimentation tank 3.2 is separated from the water production tank 3.3 by an overflow weir plate 3.22, and the top of the inclined tube sedimentation tank 3.2 is communicated with the water production tank 3.3; the wastewater flowing into the inclined tube sedimentation tank 3.2 flows along the channel between the lower part of the baffle 3.21 and the sedimentation tank 3.24, the sludge settles to the bottom of the sedimentation tank 3.24 under the action of gravity, and the clear water overflows from the top edge of the overflow weir plate 3.22 into the water production tank 3.3, realizing the separation treatment of the sludge in the wastewater; thus, through the present invention, the multi-stage treatment of the wastewater is realized, achieving the purpose of meeting the process requirements.

[0031] The bottom of the scum collection hopper 2.8 and the bottom of the inclined tube sedimentation tank 3.2 are respectively communicated with the sludge pipe 9, and the scum collected in the scum collection hopper 2.8 and the sludge deposited in the sedimentation tank 3.24 of the inclined tube sedimentation tank 3.2 are discharged through the sludge pipe 9; the primary flocculation tank 2.1, the air flotation tank 2.2, the defoaming tank 2.3, the coagulation tank 2.4 and the secondary flocculation tank 3.1 are respectively communicated with the emptying pipe 10. When cleaning each tank, it is convenient to empty and discharge the accumulated liquid inside through the emptying pipe 10.

[0032] The present invention performs primary treatment on wastewater through a primary flocculation tank 2.1 to flocculate the suspended solids in the wastewater, and then makes the suspended solids float to the water surface through aeration. The scum scraper 2.7 in the air flotation tank 2.2 skims the scum into the scum collection hopper 2.8 for easy cleaning. The defoaming tank 2.3 is used to eliminate the bubbles in the wastewater to avoid the influence of bubbles on the sedimentation of the precipitate in the subsequent process at the bottom of the tank and ensure the sedimentation effect. Then, the pollutants that are not easily air-flotated in the wastewater are flocculated and treated successively through the coagulation tank 2.4 and the secondary flocculation tank 3.1 to facilitate their precipitation in the subsequent process. Finally, the sludge in the water is precipitated through the inclined tube sedimentation tank 3.2 for easy treatment. Thus, through the continuous multi-stage treatment of wastewater by the present invention, the treatment efficiency is high, the effect is good, and it can meet the process requirements. Moreover, the overall structure is compact, the floor area is small, and the whole can be moved as a whole.

[0033] The foregoing are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A multi-stage separation and pretreatment device for wastewater, characterized in that, it includes a box body; the box body is divided into a primary air flotation separation tank and a secondary flocculation sedimentation separation tank; The primary air flotation separation tank includes a primary flocculation tank, an air flotation tank, a defoaming tank and a coagulation tank; the defoaming tank is divided into an intermediate water chamber and a defoaming chamber by a defoaming partition board; the drainage area of the primary flocculation tank is communicated with the air flotation tank through a wastewater overflow pipe, and an aeration pipe is arranged in the air flotation tank adjacent to the wastewater overflow pipe; a scum scraper is installed on the top surface of the air flotation tank, and a scum collection hopper is fixed on the inner wall of the air flotation tank adjacent to the defoaming tank; the air flotation tank is communicated with the intermediate water chamber through a wastewater flow pipe, and the defoaming chamber is communicated with the bottom of the alkaline area of the coagulation tank; The secondary flocculation sedimentation separation tank includes a secondary flocculation tank, an inclined tube sedimentation tank and a water production tank; the top of the coagulation sedimentation area of the coagulation tank is communicated with the bottom of the central cylinder in the secondary flocculation tank through a pipeline, the bottom of the secondary flocculation tank is communicated with the inclined tube sedimentation tank, and the top of the inclined tube sedimentation tank is communicated with the water production tank; The primary flocculation tank is divided into a coagulation area, the drainage area and a flocculation area by a first partition board and a second partition board; the coagulation area is provided with a wastewater inlet, the bottom of the coagulation area is communicated with the flocculation area through a pipeline, and the height of the second partition board between the drainage area and the flocculation area is less than the height of the first partition board; primary flocculation mixers are installed in both the coagulation area and the drainage area; A gate valve is installed in the defoaming tank, and the insertion plate of the gate valve is in sliding contact with the defoaming partition board; It further includes an air compressor, a dissolved air water pump and a dissolved air tank; the defoaming chamber is communicated with the water inlet of the dissolved air water pump through a water inlet pipe, the water outlet of the dissolved air water pump is communicated with the water inlet of the dissolved air tank, the air compressor is communicated with the air inlet of the dissolved air tank through an air pipe, and the liquid outlet of the dissolved air tank is communicated with the aeration pipe.

2. A multi-stage separation and pretreatment device for wastewater according to claim 1, characterized in that, The coagulation tank is divided into the alkaline area, the hardness removal area and the coagulation sedimentation area by a first baffle plate and a second baffle plate; the bottom of the hardness removal area is communicated with the bottom of the coagulation sedimentation area, and coagulation mixers are installed in the alkaline area, the hardness removal area and the coagulation sedimentation area.

3. A multi-stage separation and pretreatment device for wastewater according to claim 1, characterized in that, A partition board is fixed in the air flotation tank between the wastewater overflow pipe and the scum scraper, and a guide plate bent towards the scum scraper is fixed at the top of the partition board.

4. A multi-stage separation and pretreatment device for wastewater according to claim 1, characterized in that, A central cylinder with an open top is fixed in the secondary flocculation tank, and a secondary flocculation mixer is installed in the central cylinder.

5. A multi-stage separation and pretreatment device for wastewater according to claim 1, characterized in that, A baffle is fixed at one end of the inclined tube group of the inclined tube sedimentation tank adjacent to the secondary flocculation tank, and the inclined tube sedimentation tank is separated from the water production tank by an overflow weir plate.

6. A multi-stage separation and pretreatment device for wastewater according to claim 1, characterized in that, the bottom of the scum collection hopper and the bottom of the inclined tube sedimentation tank are respectively connected to a sludge pipe.

7. A multi-stage separation and pretreatment device for wastewater according to claim 1, characterized in that, the primary flocculation tank, the air flotation tank, the defoaming tank, the coagulation tank and the secondary flocculation tank are respectively connected to an emptying pipe.

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