Integrated treatment device for glyceride production wastewater

Abstract

The utility model belongs to the technical field of environmental protection equipment, and particularly discloses an integrated treatment device for glyceride production wastewater. The device comprises a rectangular box body, one end of the box body is provided with a liquid inlet pipe, and one end or one side far away from the liquid inlet pipe is provided with a drainage pipe; an oil separation tank, a coagulative precipitation tank, a biochemical tank, a precipitation tank and a filter tank are sequentially arranged in the box body and are communicated with one another through pipelines, a liquid outlet of a liquid inlet pipe extends to the lower part of the oil separation tank, and a water inlet of a drainage pipe is communicated with the rear end of the filter tank; an air blower and a plurality of dosing units are also arranged in the box body, medicine outlets of different dosing units are respectively and correspondingly communicated with the coagulative precipitation tank, the biochemical tank and the precipitation tank, and the air blower and the dosing units are respectively and electrically connected with a control system on the box body. According to the continuous glyceride production wastewater treatment device, the oil separation tank, the coagulative precipitation tank, the biochemical tank, the precipitation tank and the filter tank are sequentially arranged, so that glyceride production wastewater can be continuously treated, the treatment efficiency is high, the sludge output is low, the dosage of chemicals is low, and the occupied area is small.

Description

Technical Field

[0001] The utility model belongs to the technical field of environmental protection equipment, and specifically relates to an integrated treatment device for glyceride production wastewater with high treatment efficiency, low sludge output, low dosage of medicaments and small floor space. Background Art

[0002] Glyceryl triacetate is a colorless oily liquid with a faint fruity, sweet taste and a bitter organic compound at low concentrations. Glyceryl triacetate is widely used in the formulation of daily chemical flavors, mainly as a fixative. The key process in the industrial production of glyceryl triacetate is the esterification reaction. Since a lot of wastewater is produced during the esterification reaction, a water-carrying agent needs to be added during production. The water-carrying agent forms an azeotrope with the wastewater to carry the wastewater out, thereby achieving the purpose of controlling the moisture content of the reaction. As the amount of water in the reaction system decreases, the concentration of the reactants increases, thereby accelerating the reaction speed. Since the wastewater contains a water-carrying agent and some glyceryl triacetate, glycerol and acetic acid, direct discharge not only pollutes the environment, but also wastes resources.

[0003] In the prior art, for the production wastewater of triacetin, a combination of physicochemical treatment + biochemical treatment + filtration process is generally adopted, among which physicochemical treatment generally adopts oil separation, storage and regulation, coagulation sedimentation, flotation system and other processes to remove phosphorus in sewage, biochemical treatment mainly removes organic pollutants such as COD, SS, BOD, ammonia nitrogen in sewage, and the filtration process mainly ensures that the SS of the effluent meets the standard after the sewage is filtered. The coagulation sedimentation in the physicochemical treatment adopts sulfuric acid demulsification and lime to adjust the pH to remove most of the phosphorus in the sewage; the flotation system mainly adopts a pressurized dissolved air flotation system, and the auxiliary agents are mainly PAC and PAM; the biochemical system mostly adopts a contact oxidation process; the back end is supplemented by a filtration system to remove SS in the sewage, and the filtration system is usually a sand filter and an activated carbon equipment. However, simply using lime and the like to adjust pH and remove phosphorus has a low solubility, a large dosage, a high slag production, and a high sludge yield; and sulfate ions consume the calcium ions dissociated from the lime, reducing the amount of reaction between calcium ions and phosphates, and reducing the reaction efficiency with phosphates; storage and regulation not only requires large-scale regulating tanks and storage tanks, resulting in a large footprint, but also the wastewater needs to be placed for about a month to facilitate initial sedimentation, separation and water quality adjustment, and to allow the volatile substances contained in the wastewater to evaporate autonomously to reduce the subsequent treatment workload, which will also cause air pollution and reduce the wastewater treatment efficiency. Utility Model Content

[0004] According to the deficiencies of the prior art, the utility model develops an integrated treatment device for glyceride production wastewater, which has high treatment efficiency, low sludge output, low dosage of reagents and small footprint.

[0005] The utility model is implemented as follows: it comprises a rectangular box body, one end of the box body is provided with a liquid inlet pipe and one end or one side away from the liquid inlet pipe is provided with a drain pipe; a grease trap, a coagulation sedimentation tank, a biochemical tank, a sedimentation tank, and a filter tank are sequentially provided in the box body from the liquid inlet pipe to the drain pipe, and the adjacent ones are respectively connected by pipelines, the liquid outlet of the liquid inlet pipe extends to the lower part of the grease trap, and the drain outlet of the drain pipe is connected with the rear end of the filter tank;

[0006] The box body is also provided with a blower and a plurality of dosing units, and the drug outlets of different dosing units are respectively connected to the coagulation sedimentation tank, the biochemical tank, and the sedimentation tank, and the blower and the dosing unit are respectively electrically connected to the control system on the box body.

[0007] Furthermore, the oil separator tank includes an oil separator tank I, an oil separator tank II, an oil separator tank III, and a floating oil tank. The oil separator tank I, the oil separator tank II, and the oil separator tank III are arranged in series in sequence and separated from each other by oil separator plates. The floating oil tank is arranged in parallel on one side of the oil separator tank I, the oil separator tank II, and the oil separator tank III and separated from each other by overflow plates. The height of the overflow plate is lower than the height of the oil separator plate at the liquid outlet end of the same oil separator tank. The oil separator tank I, the oil separator tank II, and the oil separator tank III are connected to each other via oil separator pipes arranged on the oil separator plates.

[0008] Furthermore, an aeration pipe I is arranged at the bottom of the oil separator III, and the air inlet of the aeration pipe I is connected with the air outlet of the blower inside the box through an air supply pipe.

[0009] Furthermore, the liquid outlet of the liquid inlet pipe extends to the lower part of the oil separator tank I, the liquid inlet end of the oil separator pipe extends to the middle part of the previous oil separator tank and the liquid outlet end extends to the lower part of the next oil separator tank, and the highest end of the oil separator pipe is higher than the top of the overflow plate.

[0010] Furthermore, the coagulation sedimentation tank includes a coagulation sedimentation tank and a stirring mechanism I arranged above the coagulation sedimentation tank. A water inlet and a water outlet are provided on the side wall of the coagulation sedimentation tank. A mud discharge port is provided at the bottom of the coagulation sedimentation tank. An adjustable partition is also provided at the lower part of the coagulation sedimentation tank. The water inlet is connected to the oil separator pipe outlet of the oil separator tank III. The stirring head I of the stirring mechanism I extends into the coagulation sedimentation tank, and the drug outlet of the corresponding dosing unit extends into the coagulation sedimentation tank.

[0011] Furthermore, the coagulation sedimentation tank includes a circular ring trough body and an inverted cone trough body connected to the bottom end of the circular ring trough body, the water inlet and the water outlet are respectively arranged at the upper and lower parts of the side wall of the circular ring trough body, and the mud discharge port is arranged at the bottom of the inverted cone trough body.

[0012] Furthermore, the adjustable partition includes a driving unit and a core shaft. The driving unit is fixedly arranged on the outer wall of the circular ring trough body, the core shaft is horizontally arranged at the lower part of the circular ring trough body, and a plurality of partition plates rotatable around the core shaft are arranged on the core shaft at intervals, and the partition plates are connected to the driving end of the driving unit.

[0013] Furthermore, the biochemical pool includes an anoxic tank and an aerobic tank which are connected in series and provided with water outlets. An aeration pipe II is arranged at the bottom of the aerobic tank. The air inlet of the aeration pipe II is connected to the air outlet of the blower inside the box through an air supply pipe, and the corresponding drug outlet of the dosing unit extends to the anoxic tank and the aerobic tank respectively.

[0014] Furthermore, a sewage outlet is provided at the bottom end of the sedimentation tank, and the drug outlet of the corresponding dosing unit extends into the sedimentation tank.

[0015] Furthermore, the filter pool includes a filter tank, the top and bottom of the filter tank are respectively provided with a filtrate inlet pipe and a filtrate outlet pipe, the filtrate inlet pipe is connected to the supernatant outlet of the sedimentation tank, the top of the filter tank is fixedly provided with a water distributor connected to the filtrate inlet pipe, the lower part of the filter tank is triacetin and a glycerol plate, a sand filter layer is arranged on the filter plate in the filter tank, and the liquid inlet end of the filtrate outlet pipe is arranged below the filter plate.

[0016] Compared with the prior art, the beneficial effects of the utility model are:

[0017] 1. The utility model sequentially arranges a grease trap, a coagulation sedimentation tank, a biochemical tank, a sedimentation tank, and a filtration tank in a box body, and the adjacent ones are connected by pipelines, which not only can integrate the traditional treatment devices with different functions to reduce the floor space, but also realizes continuous and unmanned treatment of wastewater according to the characteristics of triacetin production wastewater through the ingenious combination of various functional tank bodies and equipment in the box, without the need for traditional regulating tanks and storage tanks, effectively improving the wastewater treatment efficiency and significantly reducing the wastewater treatment cost.

[0018] 2. The utility model can collect and process triacetin and glycerin in wastewater for reuse by setting up a multi-stage grease trap, which not only realizes resource utilization to reduce production costs, but also effectively reduces subsequent processing costs and improves processing efficiency. In addition, an aeration pipe I is arranged at the bottom of the last grease trap, which can fully aerate the surface of triacetin and glycerin contained in the wastewater to facilitate recovery, and can significantly improve the removal rate of grease in the wastewater.

[0019] 3. The utility model greatly reduces the floor space by setting up a coagulation sedimentation tank with a single tank structure; and by utilizing an adjustable baffle structure, the mixing of coagulant and wastewater can be completed without mechanical stirring, and the flocs can be enlarged and precipitated in combination with the collision of flocs during gravity descent, so that the slow mixing operation in the traditional sewage treatment process is realized with the help of baffles and gravity, and the adjustable baffle can also prevent the sediment from floating up again after the sedimentation operation is completed; and the dosing unit can be controlled to realize batch and multiple additions of the same or different agents, thereby effectively reducing the sludge output and the amount of agents used to reduce the treatment cost.

[0020] In summary, the utility model has the characteristics of high treatment efficiency, low sludge output, low dosage of chemicals and small footprint. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the structure of the utility model;

[0022] Figure 2 for Figure 1 A top view of

[0023] Figure 3 This is a schematic diagram of the structure of the coagulation sedimentation tank of the utility model;

[0024] Figure 4 This is a schematic diagram of the filter tank structure of the utility model;

[0025] In the figure: 1-box, 11-liquid inlet pipe, 12-drain pipe, 2-grease trap, 21-oil trap Ⅰ, 22-oil trap Ⅱ, 23-oil trap Ⅲ, 24-floating oil tank, 25-oil separator plate, 26-overflow plate, 27-oil separator pipe, 28-aeration pipe Ⅰ, 3-coagulation sedimentation tank, 31-coagulation sedimentation tank, 311-water inlet, 312-water outlet, 313-mud outlet, 314-circular trough body, 315-inverted cone trough body, 32-stirring mechanism Ⅰ , 321-mixing head Ⅰ, 33-adjustable partition, 331-drive unit, 332-core shaft, 333-partition plate, 4-biochemical tank, 41-anoxic tank, 42-aerobic tank, 43-aeration pipe Ⅱ, 5-sedimentation tank, 51-drainage outlet, 6-filtration tank, 61-filter tank, 611-filtrate inlet pipe, 612-filtrate outlet pipe, 62-water distributor, 63-filter plate, 64-sand filter layer, 7-blower, 8-dosing unit, 81-dosing pipe, 9-pump. DETAILED DESCRIPTION

[0026] The present invention is further described below in conjunction with the accompanying drawings and embodiments, but the present invention is not limited in any way. Any changes or improvements made based on the teachings of the present invention belong to the protection scope of the present invention.

[0027] like Figures 1 to 4 As shown, the utility model comprises a rectangular box body 1, one end of the box body 1 is provided with a liquid inlet pipe 11 and one end or one side away from the liquid inlet pipe 11 is provided with a drain pipe 12; a grease trap 2, a coagulation sedimentation tank 3, a biochemical tank 4, a sedimentation tank 5, and a filter tank 6 are sequentially arranged in the box body 1 from the liquid inlet pipe 11 to the drain pipe 12, and the adjacent ones are respectively connected by pipelines, the liquid outlet of the liquid inlet pipe 11 extends to the lower part of the grease trap 2, and the drain outlet of the drain pipe 12 is connected with the rear end of the filter tank 6;

[0028] The box body 1 is also provided with a blower 7 and a plurality of dosing units 8. The outlets of different dosing units 8 are respectively connected to the coagulation sedimentation tank 3, the biochemical tank 4 and the sedimentation tank 5. The blower 7 and the dosing units 8 are respectively electrically connected to the control system on the box body 1.

[0029] The oil separator 2 includes an oil separator tank I 21, an oil separator tank II 22, an oil separator tank III 23, and an oil floating tank 24. The oil separator tank I 21, the oil separator tank II 22, and the oil separator tank III 23 are arranged in series in sequence and separated from each other by an oil separator plate 25. The oil floating tank 24 is arranged in parallel on one side of the oil separator tank I 21, the oil separator tank II 22, and the oil separator tank III 23 and separated from each other by an overflow plate 26. The height of the overflow plate 26 is lower than the height of the oil separator plate 25 at the liquid outlet end of the same oil separator tank. The oil separator tank I 21, the oil separator tank II 22, and the oil separator tank III 23 are connected to each other through an oil separator pipe 27 arranged on the oil separator plate 25.

[0030] An aeration pipe I28 is arranged at the bottom of the oil separator III23, and the air inlet of the aeration pipe I28 is connected to the air outlet of the blower 7 inside the box body 1 through an air supply pipeline.

[0031] The liquid outlet of the liquid inlet pipe 11 extends to the lower part of the oil separator tank I21, the liquid inlet end of the oil separator pipe 27 extends to the middle part of the previous oil separator tank and the liquid outlet end extends to the lower part of the next oil separator tank, and the highest end of the oil separator pipe 27 is higher than the top of the overflow plate 26.

[0032] The coagulation sedimentation tank 3 includes a coagulation sedimentation tank 31 and a stirring mechanism I32 arranged above the coagulation sedimentation tank 31. A water inlet 311 and a water outlet 312 are provided on the side wall of the coagulation sedimentation tank 31. A mud discharge port 313 is provided at the bottom of the coagulation sedimentation tank 31. An adjustable partition 33 is also provided at the lower part of the coagulation sedimentation tank 31. The water inlet 311 is connected to the outlet of the oil separator pipe 27 of the oil separator tank III23. The stirring head I321 of the stirring mechanism I32 extends into the coagulation sedimentation tank 31, and the drug outlet of the corresponding dosing unit 8 extends into the coagulation sedimentation tank 31.

[0033] The coagulation sedimentation tank 31 includes a circular ring trough body 314 and an inverted cone trough body 315 connected to the bottom end of the circular ring trough body 314 . The water inlet 311 and the water outlet 312 are respectively arranged at the upper and lower parts of the side wall of the circular ring trough body 314 . The mud discharge port 313 is arranged at the bottom of the inverted cone trough body 315 .

[0034] The adjustable partition 33 includes a driving unit 331 and a core shaft 332. The driving unit 331 is fixedly arranged on the outer wall of the annular groove body 314. The core shaft 332 is horizontally arranged at the lower part of the annular groove body 314. A plurality of partition plates 333 that can rotate around the core shaft 332 are arranged at intervals on the core shaft 332. The partition plates 333 are connected to the driving end of the driving unit 331.

[0035] The biochemical pool 4 includes an anoxic tank 41 and an aerobic tank 42 which are connected in series and provided with water outlets. An aeration pipe II 43 is arranged at the bottom of the aerobic tank 42. The air inlet of the aeration pipe II 43 is connected to the air outlet of the blower 7 inside the box body 1 through an air supply pipe, and the corresponding drug outlet of the dosing unit 8 extends to the anoxic tank 41 and the aerobic tank 42 respectively.

[0036] The bottom end of the sedimentation tank 5 is provided with a sewage outlet 51 , which corresponds to the drug outlet of the dosing unit 8 extending into the sedimentation tank 5 .

[0037] The filter pool 6 includes a filter tank 61, and a filtrate inlet pipe 611 and a filtrate outlet pipe 612 are respectively provided at the top and bottom ends of the filter tank 61. The filtrate inlet pipe 611 is connected to the supernatant outlet of the sedimentation tank 5. A water distributor 62 connected to the filtrate inlet pipe 611 is fixedly provided at the top of the filter tank 61. A filter plate 63 is horizontally arranged at the lower part of the filter tank 61. A sand filter layer 64 is arranged on the filter plate 63 in the filter tank 61, and the liquid inlet end of the filtrate outlet pipe 612 is arranged below the filter plate 63.

[0038] The working principle and working process of this utility model:

[0039] like Figures 1 to 4As shown, the triacetin production wastewater is first passed into the grease trap 2, and then degreased through two-stage overflow of the grease trap I 21 and the grease trap II 22, and finally flows into the grease trap III 23 through the grease trap pipe 27 to aerate the wastewater containing grease again, so that the grease overflows from the top of the overflow plate 26 to the floating oil tank 24 for recovery and treatment. The wastewater after oil separation treatment is introduced into the coagulation sedimentation tank 31 through the water inlet 311, and inorganic coagulants (such as PAC) and organic coagulants (such as PAM) are added into the coagulation sedimentation tank 31 through the dosing unit 8. Then, the stirring mechanism I32 is controlled to quickly coagulate. After the coagulation is completed, the stirring mechanism I32 is closed, and then the driving unit 331 is controlled to drive the partition plate 333 to rotate to make the wastewater flow into the inverted cone trough body 315. The small flocs in the wastewater are mixed under the action of the partition plate 333, and the flocs are enlarged and precipitated through the collision effect during the gravity descent. Finally, the wastewater after coagulation and sedimentation is discharged from the water outlet 312 to the biochemical pool 4 for treatment, and the mud outlet 313 is opened as needed to discharge the sediment. The wastewater after sedimentation treatment is first passed into the anoxic tank 41, and active bacteria are added through the dosing unit 8 for anaerobic fermentation to decompose, metabolize and digest the organic matter in the wastewater. Then the supernatant is passed into the aerobic tank 42, and active bacteria are added through the dosing unit 8 and biological aeration is performed through the aeration pipe II 43 to further oxidize and decompose the organic matter in the wastewater. The supernatant of the aerobic tank 42 is passed into the sedimentation tank 5 and an inorganic coagulant (such as PAC) is added and mechanically stirred to further remove the inorganic matter in the wastewater. The precipitate is discharged from the sewage outlet 51 at the bottom, and the supernatant is passed into the filter tank 61. After the wastewater is passed into the filter tank 61 through the filtrate inlet pipe 611, it is sprayed on the sand filter layer 64 through the water distributor 62. The wastewater passes through the sand filter layer 64 and the filter plate 63 by its own weight, and the large particles and most of the pigments therein are filtered out. The clear liquid finally obtained meets the discharge standard for external discharge or reuse.

[0040] The above is only a preferred specific implementation of the utility model, but the protection scope of the utility model is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the utility model should be included in the protection scope of the utility model. Therefore, the protection scope of the utility model should be based on the protection scope of the claims.

Claims

1. An integrated treatment device for glyceride production wastewater, comprising a rectangular box (1), one end of the box (1) is provided with a liquid inlet pipe (11) and one end or one side away from the liquid inlet pipe (11) is provided with a drain pipe (12); characterized in that: The box body (1) is provided with a grease trap (2), a coagulation sedimentation tank (3), a biochemical tank (4), a sedimentation tank (5), and a filter tank (6) in sequence from the liquid inlet pipe (11) to the drain pipe (12), and adjacent ones are connected by pipelines, the liquid outlet of the liquid inlet pipe (11) extends to the lower part of the grease trap (2), and the drain outlet of the drain pipe (12) is connected to the rear end of the filter tank (6); A blower (7) and a plurality of dosing units (8) are also provided in the box (1); the drug outlets of the different dosing units (8) are respectively connected to the coagulation sedimentation tank (3), the biochemical tank (4), and the sedimentation tank (5); and the blower (7) and the dosing units (8) are respectively electrically connected to the control system on the box (1).

2. The integrated treatment device for glyceride production wastewater according to claim 1, characterized in that: The oil separator (2) comprises an oil separator tank I (21), an oil separator tank II (22), an oil separator tank III (23), and an oil floating tank (24). The oil separator tank I (21), the oil separator tank II (22), and the oil separator tank III (23) are arranged in series in sequence and separated from each other by an oil separator plate (25). The oil floating tank (24) is arranged in parallel on one side of the oil separator tank I (21), the oil separator tank II (22), and the oil separator tank III (23) and separated from each other by an overflow plate (26). The height of the overflow plate (26) is lower than the height of the oil separator plate (25) at the liquid outlet end of the same oil separator tank. The oil separator tank I (21), the oil separator tank II (22), and the oil separator tank III (23) are connected to each other via an oil separator pipe (27) arranged on the oil separator plate (25).

3. The integrated treatment device for glyceride production wastewater according to claim 2, characterized in that: An aeration pipe I (28) is arranged at the bottom of the oil separator tank III (23), and the air inlet of the aeration pipe I (28) is connected to the air outlet of the blower (7) inside the box body (1) through an air supply pipeline.

4. The integrated treatment device for glyceride production wastewater according to claim 2, characterized in that: The liquid outlet of the liquid inlet pipe (11) extends to the lower part of the oil separator tank I (21), the liquid inlet end of the oil separator pipe (27) extends to the middle part of the previous oil separator tank and the liquid outlet end extends to the lower part of the next oil separator tank, and the highest end of the oil separator pipe (27) is higher than the top end of the overflow plate (26).

5. The integrated treatment device for glyceride production wastewater according to claim 2, 3 or 4, characterized in that: The coagulation sedimentation tank (3) comprises a coagulation sedimentation tank (31) and a stirring mechanism I (32) arranged above the coagulation sedimentation tank (31); a water inlet (311) and a water outlet (312) are provided on the side wall of the coagulation sedimentation tank (31); a mud discharge port (313) is provided at the bottom of the coagulation sedimentation tank (31); an adjustable baffle (33) is also provided at the lower part of the coagulation sedimentation tank (31); the water inlet (311) is connected to the outlet of the oil separator pipe (27) of the oil separator tank III (23); a stirring head I (321) of the stirring mechanism I (32) extends into the coagulation sedimentation tank (31); and a drug outlet of a corresponding dosing unit (8) extends into the coagulation sedimentation tank (31).

6. The integrated treatment device for glyceride production wastewater according to claim 5, characterized in that: The coagulation sedimentation tank (31) comprises a circular annular tank body (314) and an inverted conical tank body (315) connected to the bottom end of the circular annular tank body (314); the water inlet (311) and the water outlet (312) are respectively arranged at the upper part and the lower part of the side wall of the circular annular tank body (314); and the mud discharge port (313) is arranged at the bottom of the inverted conical tank body (315).

7. The integrated treatment device for glyceride production wastewater according to claim 6, characterized in that: The adjustable partition (33) comprises a driving unit (331) and a core shaft (332); the driving unit (331) is fixedly arranged on the outer wall of the annular groove body (314); the core shaft (332) is horizontally arranged at the lower part of the annular groove body (314); a plurality of partition plates (333) rotatable around the core shaft (332) are arranged at intervals on the core shaft (332); and the partition plates (333) are connected to the driving end of the driving unit (331).

8. The integrated treatment device for glyceride production wastewater according to claim 5, characterized in that: The biochemical pool (4) comprises an anoxic tank (41) and an aerobic tank (42) which are sequentially connected in series and provided with water outlets. An aeration pipe II (43) is arranged at the bottom of the aerobic tank (42). The air inlet of the aeration pipe II (43) is connected to the air outlet of the blower (7) inside the box (1) through an air supply pipe, and the corresponding drug outlet of the dosing unit (8) extends into the anoxic tank (41) and the aerobic tank (42) respectively.

9. The integrated treatment device for glyceride production wastewater according to claim 5, characterized in that: The bottom end of the sedimentation tank (5) is provided with a sewage outlet (51), corresponding to the drug outlet of the drug adding unit (8) extending into the sedimentation tank (5).

10. The integrated treatment device for glyceride production wastewater according to claim 5, characterized in that: The filter tank (6) comprises a filter tank (61), wherein a filtrate inlet pipe (611) and a filtrate outlet pipe (612) are respectively arranged at the top and bottom of the filter tank (61), wherein the filtrate inlet pipe (611) is connected to the supernatant outlet of the sedimentation tank (5), and a water distributor (62) connected to the filtrate inlet pipe (611) is fixedly arranged at the top of the filter tank (61), wherein a filter plate (63) is transversely arranged at the bottom of the filter tank (61), and a sand filter layer (64) is arranged on the filter plate (63) in the filter tank (61), and the liquid inlet end of the filtrate outlet pipe (612) is arranged below the filter plate (63).

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