A method for treating wastewater from the production of power battery structural parts

Abstract

The present invention discloses a method for treating production wastewater of power battery structural parts, which treats the cleaning wastewater in the production of power battery structural parts and sequentially includes the following steps: the cleaning wastewater in the production of power battery structural parts enters the cleaning water adjustment tank for adjustment after being separated by an oil separation tank; the lower layer water after adjustment in the cleaning water adjustment tank enters the membrane treatment system through an intermediate tank for membrane treatment, and the upper layer water enters the petroleum wastewater treatment system for treatment. The water phases of the air flotation equipment and the three-phase separator in the petroleum wastewater treatment system are returned to the cleaning water adjustment tank to participate in the adjustment; if the clear liquid after treatment in the membrane treatment system meets the standards, it enters the clean water tank, and if it does not meet the standards, it enters the biochemical treatment system for biochemical treatment. The concentrated liquid is refluxed back to the intermediate tank, and the concentrated liquid in the intermediate tank is discharged into the petroleum wastewater treatment system; the clean water after treatment in the biochemical treatment system enters the cleaning water. The present invention realizes the effective treatment of the production wastewater of power battery structural parts.

Description

Technical Field

[0001] The present invention relates to the field of environmental protection water treatment, and particularly to a method for treating wastewater from the production of power battery structural parts. Background Art

[0002] In recent years, new energy vehicles have developed rapidly. New energy vehicles include pure electric vehicles, range-extended electric vehicles, hybrid vehicles, fuel cell electric vehicles, hydrogen engine vehicles, and other new energy vehicles. Among them, the technology of pure electric vehicles is the most mature, and its prospect is widely optimistic and is generally recognized as the most likely to replace traditional vehicles. The most core component in a pure electric vehicle is the power battery, and its specific capacity, safety performance, production cost, etc. are the key factors determining whether pure electric vehicles can be widely promoted and used. However, a large amount of production wastewater is generated during the manufacturing process of power batteries. Among them, the wastewater quality from the production of power battery structural parts is relatively complex.

[0003] With the acceleration of the industrialization process of power batteries, the amount of production wastewater, especially cleaning wastewater, from the production of power battery structural parts is increasing, and its environmental risk to the ecological environment and human health is becoming more and more serious. However, there is currently no effective solution for the production wastewater of power battery structural parts at home and abroad. The existing treatment solution for the production wastewater of power battery structural parts is as follows: the cleaning wastewater enters the cleaning water adjustment tank for adjustment after oil separation in the oil separation tank, then enters the intermediate tank for sedimentation, the water coming out of the intermediate tank enters the traditional biochemical treatment system for biochemical treatment, the clear liquid enters the clear water tank, the sludge enters the biochemical sludge tank, and then is sent to the plate and frame filter press for filtration. The filter cake is used as solid waste, and the filtrate is returned to the biochemical system for further treatment.

[0004] The water quality of the clear water tank after the treatment of the existing treatment solution for the production wastewater of power battery structural parts cannot meet the standards and needs further treatment to reach the standard for discharge.

[0005] Finding an effective solution for the production wastewater of power battery structural parts has become an urgent problem to be solved in the industry. Summary of the Invention

[0006] Based on the above problems, the present invention provides a method for treating wastewater from the production of power battery structural parts, aiming to improve at least one of the problems mentioned in the background art.

[0007] The technical solution is: a method for treating wastewater from the production of power battery structural parts, which treats the cleaning wastewater from the production of power battery structural parts and sequentially includes the following steps:

[0008] The cleaning wastewater from the production of power battery structural parts enters the cleaning water adjustment tank for adjustment after oil separation in the oil separation tank;

[0009] The lower-layer water after adjustment in the cleaning water regulation tank enters the membrane treatment system through the intermediate tank for membrane treatment, and the upper-layer water enters the petroleum water treatment system for treatment. The water phases of the air flotation equipment and the three-phase separator in the petroleum water treatment system return to the cleaning water regulation tank to participate in the regulation;

[0010] If the clarified liquid after treatment in the membrane treatment system meets the standards, it enters the clear water tank; if it does not meet the standards, it enters the biochemical treatment system for biochemical treatment. The concentrated liquid flows back to the intermediate tank, and the concentrated liquid in the intermediate tank is discharged into the petroleum water treatment system;

[0011] The clear water after treatment in the biochemical treatment system enters the cleaning water.

[0012] Optionally, the power battery structural member is for protecting the components inside the power battery, including a battery case, a battery cover, a battery bottom plate, and metal fittings.

[0013] Optionally, the production wastewater of the power battery structural member is the cleaning wastewater for the production of the power battery structural member

[0014] Optionally, the membrane treatment system includes, arranged in sequence according to the treatment order: a first-stage membrane tank, a first-stage membrane product water tank, a second-stage membrane tank, a second-stage membrane product water tank, a third-stage membrane tank, and a third-stage membrane product water tank.

[0015] Optionally, the concentrated liquid reflux ratio after treatment in the first-stage membrane tank > the concentrated liquid reflux ratio after treatment in the second-stage membrane tank > the concentrated liquid reflux ratio after treatment in the third-stage membrane tank.

[0016] Optionally, the concentrated liquid reflux ratio after treatment in the first-stage membrane tank = 100%, the concentrated liquid reflux ratio after treatment in the second-stage membrane tank = 40%, and the concentrated liquid reflux ratio after treatment in the third-stage membrane tank = 20%.

[0017] Optionally, the biochemical treatment system includes, arranged in sequence according to the treatment order: at least one anaerobic tank, a first sedimentation tank, an anoxic tank, at least one aerobic tank, a middle sedimentation tank, and a second sedimentation tank.

[0018] Optionally, the power battery structural member production wastewater treatment system further includes a biochemical sludge treatment system, and the biochemical sludge treatment system includes, arranged in sequence according to the treatment order: a biochemical sludge tank, a biochemical filter press, and a sludge storage room.

[0019] Optionally, the filtrate generated by the biochemical filter press returns to the cleaning water regulation tank for adjustment.

[0020] Principle and beneficial effects of the invention:

[0021] The inventor team found that in the treatment of the production wastewater of power battery structural parts, the reason why the water quality after treatment by the existing treatment scheme for the production wastewater of power battery structural parts needs further treatment is that the particularity of the production wastewater of power battery structural parts has not been considered. The water quality of the production wastewater of power battery structural parts is basically as shown in Table 1 below (the data in Table 1 are the values detected after the production cleaning wastewater of power battery structural parts enters the cleaning water regulation tank through the oil separator without adding chemical agents, only adjusting the water volume and balancing the water quality):

[0022] Table 1 Original water quality of the production wastewater of power battery structural parts

[0023]

[0024] It can be seen from Table 1 that the main pollutants in the production wastewater of power battery structural parts are all relatively high, and the contents of COD, BOD, SS, and petroleum are all much higher than those of ordinary wastewater. The ratio of BOD / COD is <0.3, and the conductivity is also relatively high, making the treatment difficult.

[0025] In the present invention, a three-stage membrane treatment system is set before the biochemical treatment system, and the reflux ratio of the concentrated liquid after the treatment in the first-stage membrane tank > the reflux ratio of the concentrated liquid after the treatment in the second-stage membrane tank > the reflux ratio of the concentrated liquid after the treatment in the third-stage membrane tank. The water phase separated by the three-phase separator and the water phase separated by the air flotation device are returned to the cleaning water regulation tank. The upper-layer oil-water mixture in the cleaning water regulation tank, the concentrated liquid in the intermediate tank, and the water layer in the physical and chemical sludge tank are sent to the air flotation device. Through the dynamic separation of the air flotation device + the static separation of the three-phase separator, the production cleaning wastewater of power battery structural parts can be treated into wastewater that can be discharged without adding external chemical agents. Brief Description of the Drawings

[0026] Figure 1 It is a schematic diagram of the treatment process flow of the present invention. Detailed Embodiments

[0027] The present invention will be further described below in conjunction with the drawings.

[0028] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "longitudinal", "lateral", "horizontal", "inner", "outer", "front", "rear", "top", "bottom", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the present invention is usually placed during use. 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.

[0029] In the description of the present invention, it should also be noted that, unless otherwise clearly specified and defined, the terms "set", "provided with", "installed", "connected", and "communicated" should be understood in a broad sense. For example, it can be fixedly connected, detachably connected, or integrally connected; it can be directly communicated or indirectly communicated through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0030] In the present invention, the power battery structural member refers to a component that protects the internal components of the power battery, including a battery case, a battery cover, a battery bottom plate, and metal fittings.

[0031] In the present invention, the production wastewater of the power battery structural member refers to the cleaning wastewater generated during the production of the power battery structural member.

[0032] Please refer to Figure 1 , the embodiment of the present invention provides a treatment system for the production wastewater of the power battery structural member, including: an oil separation tank, a cleaning water adjustment tank, an intermediate tank, a membrane treatment system, and a clear water tank, which are arranged in sequence according to the treatment order.

[0033] Furthermore, the membrane treatment system includes: a first-stage membrane tank, a first-stage membrane product water tank, a second-stage membrane tank, a second-stage membrane product water tank, a third-stage membrane tank, and a third-stage membrane product water tank, which are arranged in sequence according to the treatment order.

[0034] Furthermore, the membrane installed in the first-stage membrane tank is a tubular membrane, and the membranes installed in the second-stage membrane tank and the third-stage membrane tank are both nanofiltration membranes.

[0035] Furthermore, the treatment system for the production wastewater of the power battery structural member further includes an oil and water treatment system. The oil and water treatment system treats the upper-layer oil and water in the cleaning water adjustment tank and the concentrated liquid formed during the operation of the intermediate tank. The oil and water treatment system includes: a flotation device, a three-phase separator, and an oil and grease collection tank, which are arranged in sequence according to the treatment order. The flotation device dynamically separates to form three phases (from top to bottom: oil phase, water phase, and sludge phase), and the three-phase separator statically separates the oil phase coming from the flotation device to form three phases (from top to bottom: oil phase, water phase, and sludge phase). The oil and water treatment system further includes: a physicochemical sludge tank and a physicochemical filter press, which are arranged in sequence according to the treatment order. The physicochemical sludge tank is used to treat the sludge discharged from the flotation device and the three-phase separator, and the sludge cake of the physicochemical filter press and the oil and grease in the oil and grease collection tank are transported and treated as hazardous waste.

[0036] Furthermore, for better treatment effect, a first pipeline and a second pipeline are connected in parallel between the air flotation equipment and the cleaning water regulating tank. The three-phase separator is connected with a third pipeline, and the other end of the third pipeline is connected to the first pipeline. The physical and chemical sludge tank is also connected with a fifth pipeline and a sixth pipeline, and the other end of the sixth pipeline is connected to the physical and chemical filter press. The intermediate tank is connected with a seventh pipeline, and the other end of the seventh pipeline is connected to the second pipeline. The other end of the fifth pipeline is connected to the seventh pipeline. The first pipeline and the third pipeline return the aqueous phase separated by the three-phase separator and the aqueous phase separated by the air flotation equipment to the cleaning water regulating tank. The upper layer of oil-water mixture in the cleaning water regulating tank, the concentrated liquid in the intermediate tank, and the water layer in the physical and chemical sludge tank are sent to the air flotation equipment through the second pipeline, the fifth pipeline, and the seventh pipeline. The sixth pipeline returns the filtrate of the physical and chemical filter press to the physical and chemical sludge tank.

[0037] In the present invention, the process of forming the concentrated liquid in the intermediate tank is as follows: The water in the intermediate water layer is transported from the cleaning water regulating tank to the intermediate tank until a certain liquid level is reached. Then, the water in the intermediate tank is transported to the membrane treatment system for treatment. The water with a certain height of liquid level in the intermediate tank remains in the intermediate tank. After the membrane treatment system finishes the treatment, the water in the intermediate water layer is transported from the cleaning water regulating tank to the intermediate tank to the same liquid level again. Then, the water in the intermediate tank is transported to the membrane treatment system for treatment. The liquid level with a certain height at the bottom of the intermediate tank remains in the intermediate tank, and the water with the same height of liquid level in the intermediate tank remains in the intermediate tank. The next cycle is carried out according to this operation mode. After multiple operations, the liquid remaining in the intermediate tank is the concentrated liquid.

[0038] Furthermore, for better treatment effect, the intermediate tank is also connected with a fourth pipeline, and the other end of the fourth pipeline is connected to the first-stage membrane tank. The first-stage membrane product water tank is connected with an eighth pipeline, and the other end of the eighth pipeline is connected to the second-stage membrane tank. The second-stage membrane product water tank is connected with a ninth pipeline, and the other end of the ninth pipeline is connected to the third-stage membrane tank. The fourth pipeline returns the concentrated liquid of the first-stage membrane tank to the intermediate tank, the eighth pipeline returns the concentrated liquid of the second-stage membrane tank to the first-stage membrane product water tank, and the ninth pipeline returns the concentrated liquid of the third-stage membrane tank to the second-stage membrane product water tank.

[0039] Furthermore, for better treatment effect, the proportion of the concentrated liquid returned by the fourth pipeline, the eighth pipeline, and the ninth pipeline in the concentrated liquid generated at this stage gradually decreases. Further, the fourth pipeline returns all the concentrated liquid of the first-stage membrane tank to the intermediate tank, the eighth pipeline returns 40% of the concentrated liquid of the second-stage membrane tank to the first-stage membrane product water tank, and the ninth pipeline returns 20% of the concentrated liquid of the third-stage membrane tank to the second-stage membrane product water tank.

[0040] Furthermore, the membrane treatment system also includes a cleaning system, which is respectively connected to the first-stage membrane tank, the second-stage membrane tank, and the third-stage membrane tank. The cleaning system is used to be turned on when the first-stage membrane tank, the second-stage membrane tank, and the third-stage membrane tank are not working, and to clean the membranes in the first-stage membrane tank, the second-stage membrane tank, and the third-stage membrane tank.

[0041] The present invention provides a three-stage membrane treatment system. The reflux ratio of the concentrated liquid after treatment in the first-stage membrane tank > the reflux ratio of the concentrated liquid after treatment in the second-stage membrane tank > the reflux ratio of the concentrated liquid after treatment in the third-stage membrane tank. The aqueous phase separated by the three-phase separator and the aqueous phase separated by the air flotation device are returned to the cleaning water adjustment tank. The upper-layer oil-water mixture in the cleaning water adjustment tank, the concentrated liquid in the intermediate tank, and the water layer in the physicochemical sludge tank are sent to the air flotation device. Through the dynamic separation of the air flotation device + the static separation of the three-phase separator, the cleaning wastewater for the production of power battery structural parts can be treated into wastewater that can be discharged without adding external chemical agents.

[0042] Further, when the raw water quality of the cleaning wastewater for the production of power battery structural parts deteriorates and the treated wastewater does not meet the standards and cannot enter the clean water tank, the power battery structural parts production wastewater treatment system further includes a biochemical treatment system and a biochemical sludge treatment system. The biochemical treatment system is located between the membrane treatment system and the clean water tank, and the biochemical sludge treatment system is located after the membrane treatment system for treating the biochemical sludge discharged from the biochemical sludge treatment system.

[0043] Further, the biochemical treatment system includes, in the order of treatment: at least one anaerobic tank, a first sedimentation tank, an anoxic tank, at least one aerobic tank, a middle sedimentation tank, and a second sedimentation tank.

[0044] Further, the biochemical sludge treatment system includes, in the order of treatment: a biochemical sludge tank, a biochemical filter press, and a sludge storage room. The sludge in the sludge storage room is transported out as solid waste for treatment.

[0045] The power battery structural parts production wastewater treatment method provided by the embodiments of the present invention is treated using the power battery structural parts production wastewater treatment system provided by the embodiments of the present invention.

[0046] In the following Examples 1 - 3 and Comparative Examples 1 - 6, the equipment size of the power battery structural parts production wastewater treatment system is designed according to the treatment capacity of 240 m 3 / d of the raw water of the cleaning wastewater for the production of power battery structural parts, and those skilled in the art can design according to needs.

[0047] In the following Examples 1 - 3 and Comparative Examples 1 - 6, the number of anaerobic tanks in the biochemical treatment system is 2, which are successively the first-stage UASB anaerobic tank and the second-stage UASB anaerobic tank. The number of aerobic tanks is 6, and the 6 aerobic tanks are arranged in sequence. The second sedimentation tank is an inclined tube sedimentation tank.

[0048] Example 1

[0049] In this embodiment, in the production wastewater treatment system of the power battery structural parts of the present invention, the biochemical treatment system is not started, the membrane treatment system and the petroleum wastewater treatment system are started, and the water quality of the treatment object is as shown in Table 2 below, and the water quality of the tertiary membrane product water tank is as shown in Table 2 below.

[0050] In this embodiment, the concentrated liquid reflux ratio after the treatment in the primary membrane tank is 100%, the concentrated liquid reflux ratio after the treatment in the secondary membrane tank is 40%, and the concentrated liquid reflux ratio after the treatment in the tertiary membrane tank is 20%.

[0051] Comparative Example 1

[0052] Compared with Example 1, in this Comparative Example 1, except that the water quality of the treatment object deteriorates, the rest is the same as that of Example 1.

[0053] The concentrated liquid reflux ratio after the treatment in the primary membrane tank is 100%, the concentrated liquid reflux ratio after the treatment in the secondary membrane tank is 40%, and the concentrated liquid reflux ratio after the treatment in the tertiary membrane tank is 20%.

[0054] The water quality of the treatment object is as shown in Table 2 below, and the water quality of the tertiary membrane product water tank is as shown in Table 2 below.

[0055] Example 2

[0056] This embodiment is carried out on the basis of Comparative Example 1 (i.e., including Comparative Example 1). When it is detected in Comparative Example 1 that the water quality of the tertiary membrane product water tank does not meet the discharge standard, the biochemical treatment system is started for biochemical treatment.

[0057] The water quality of the effluent of the biochemical treatment system is as shown in Table 2 below.

[0058] Comparative Example 2

[0059] In this comparative example, in the production wastewater treatment system of the power battery structural parts of the present invention, the membrane treatment system is closed, the biochemical treatment system and the petroleum wastewater treatment system are started, and the water quality of the treatment object is the same as that of Example 1.

[0060] The water quality of the effluent of the biochemical treatment system is as shown in Table 2 below.

[0061] Comparative Example 3

[0062] The water quality of the treatment object in Comparative Example 3 is the same as that of Example 1, and the difference is that: the concentrated liquid reflux ratio after the treatment in the primary membrane tank is 50%, the concentrated liquid reflux ratio after the treatment in the secondary membrane tank is 50%, and the concentrated liquid reflux ratio after the treatment in the tertiary membrane tank is 50%.

[0063] The water quality of the tertiary membrane product water tank is as shown in Table 2 below.

[0064] Comparative Example 4

[0065] In Comparative Example 4, the water quality of the treatment object was the same as that in Example 2, except that the membrane treatment system and the biochemical treatment system were turned on, and the petroleum wastewater treatment system was not turned on.

[0066] The concentration liquid reflux ratio after the treatment in the first-stage membrane tank was 100%, the concentration liquid reflux ratio after the treatment in the second-stage membrane tank was 40%, and the concentration liquid reflux ratio after the treatment in the third-stage membrane tank was 20%.

[0067] The effluent water quality of the biochemical treatment system is shown in Table 2 below.

[0068] Comparative Example 5

[0069] In Comparative Example 5, the water quality of the treatment object was the same as that in Example 2, and the membrane treatment system, the biochemical treatment system, and the petroleum wastewater treatment system were all turned on. The difference was that in the petroleum wastewater treatment system, the three-phase separator was not turned on.

[0070] The concentration liquid reflux ratio after the treatment in the first-stage membrane tank was 100%, the concentration liquid reflux ratio after the treatment in the second-stage membrane tank was 40%, and the concentration liquid reflux ratio after the treatment in the third-stage membrane tank was 20%.

[0071] The effluent water quality of the biochemical treatment system is shown in Table 2 below.

[0072] Comparative Example 6

[0073] In Comparative Example 6, the water quality of the treatment object was the same as that in Example 2, and the membrane treatment system, the biochemical treatment system, and the petroleum wastewater treatment system were all turned on. The difference was that in the petroleum wastewater treatment system, the air flotation equipment was not turned on.

[0074] The concentration liquid reflux ratio after the treatment in the first-stage membrane tank was 100%, the concentration liquid reflux ratio after the treatment in the second-stage membrane tank was 40%, and the concentration liquid reflux ratio after the treatment in the third-stage membrane tank was 20%.

[0075] The effluent water quality of the biochemical treatment system is shown in Table 2 below.

[0076] Example 3

[0077] In Example 3, the water quality of the treatment object was the same as that in Example 2, and the membrane treatment system, the biochemical treatment system, and the petroleum wastewater treatment system were all turned on. The difference was that the biochemical filter press was connected with a tenth pipeline, the other end of the tenth pipeline was connected with the cleaning water regulating tank, and the press filtrate of the biochemical filter press was returned to the cleaning water regulating tank.

[0078] The concentration liquid reflux ratio after the treatment in the first-stage membrane tank was 100%, the concentration liquid reflux ratio after the treatment in the second-stage membrane tank was 40%, and the concentration liquid reflux ratio after the treatment in the third-stage membrane tank was 20%.

[0079] The effluent water quality of the biochemical treatment system is shown in Table 2 below.

[0080] Table 2

[0081]

[0082] As can be seen from Table 2, in Example 1, when the water quality of the produced wastewater of the power battery structural parts being treated is not too bad, without starting the biochemical treatment system, the water quality of the tertiary membrane production water tank can be discharged into the clear water tank.

[0083] However, in Comparative Example 1 with relatively bad water quality, the water quality of the tertiary membrane production water tank does not meet the standard and cannot be discharged into the clear water tank.

[0084] In Example 2, after the water in the tertiary membrane production water tank of Comparative Example 1 is treated by the biochemical treatment system, it can meet the standard and be sent to the clear water tank.

[0085] In Comparative Example 2, when the treated water quality is the same as that in Example 1 (the water quality is not too bad), but directly enters the biochemical system for treatment without passing through the membrane treatment system, the effluent water quality after the biochemical system treatment does not meet the standard and cannot be discharged into the clear water tank.

[0086] Compared with Example 1 (the water quality is not too bad), in Comparative Example 3, under the same water quality conditions, with the same reflux ratio of each stage of concentrated liquid, the water quality of the tertiary membrane production water tank does not meet the discharge standard and cannot be discharged into the clear water tank.

[0087] Compared with Example 2 (bad water quality), in Comparative Example 4, under the same water quality conditions, because the petroleum water treatment system is not started, the water quality from the biochemical treatment system does not meet the discharge standard and cannot be discharged into the clear water tank.

[0088] Compared with Example 2, in Comparative Example 5, under the same water quality conditions, although the petroleum water treatment system is started, but because the static three-phase separator in the petroleum water treatment system is not started, the water quality from the biochemical treatment system does not meet the discharge standard and cannot be discharged into the clear water tank.

[0089] Compared with Example 2, in Comparative Example 6, under the same water quality conditions, although the petroleum water treatment system is started, but because the dynamic separation air flotation equipment in the petroleum water treatment system is not started, the water quality from the biochemical treatment system does not meet the discharge standard and cannot be discharged into the clear water tank.

[0090] Compared with Example 2, in Example 3, under the same water quality conditions, because the pressure filtrate of the biochemical filter press is returned to the cleaning water adjustment tank, the treatment effect is better than that in Example 2.

[0091] In the present invention, unless otherwise specified, all are prior arts.

[0092] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, various modifications and variations can be made to the present invention. Any modification, equivalent replacement, improvement, 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 method for treating wastewater from the production of power battery structural parts, which is used to treat wastewater from the production of power battery structural parts, characterized in that: The following steps are included in sequence: The cleaning wastewater from the production of power battery structural parts is separated by oil in the oil separator and then enters the cleaning water regulating tank for regulation; The lower layer of water after adjustment in the cleaning water regulating tank enters the membrane treatment system through the intermediate tank for membrane treatment, and the upper layer of water enters the petroleum water treatment system for treatment. The flotation equipment of the petroleum water treatment system and the water phase of the three-phase separator return to the cleaning water regulating tank for adjustment; The clear liquid treated by the membrane treatment system will enter the clear water tank if it meets the standards, and will enter the biochemical treatment system for biochemical treatment if it does not meet the standards. The concentrated liquid will flow back to the intermediate tank, and the concentrated liquid in the intermediate tank will be discharged into the petroleum water treatment system. The clean water after treatment by the biochemical treatment system enters the cleaning water; The membrane treatment system includes: a primary membrane pool, a primary membrane water production tank, a secondary membrane pool, a secondary membrane water production tank, a tertiary membrane pool and a tertiary membrane water production tank, which are arranged in a treatment order. All the concentrated liquid in the primary membrane pool is returned to the intermediate pool, 40% of the concentrated liquid in the secondary membrane pool is returned to the primary membrane water production tank, and 20% of the concentrated liquid in the tertiary membrane pool is returned to the secondary membrane water production tank.

2. The method for treating wastewater from the production of power battery structural parts according to claim 1, characterized in that: The power battery structural parts are components for protecting the interior of the power battery, including a battery shell, a battery cover, a battery bottom plate and metal accessories.

3. The method for treating wastewater from production of power battery structural parts according to claim 1, characterized in that: The power battery structural component production wastewater is power battery structural component production cleaning wastewater.

4. The method for treating wastewater produced by power battery structural parts according to claim 1 is characterized in that the biochemical treatment system includes: at least one anaerobic tank, a first sedimentation tank, an anoxic tank, at least one aerobic tank, a medium sedimentation tank and a second sedimentation tank, which are arranged in the order of treatment.

5. The method for treating wastewater from the production of power battery structural parts according to claim 4 is characterized in that it also includes a biochemical sludge treatment system, which includes: a biochemical sludge pool, a biochemical filter press and a sludge temporary storage room, which are arranged in a treatment order.

6. The method for treating wastewater produced by the production of power battery structural parts according to claim 5 is characterized in that the filtrate produced by the biochemical filter press is returned to the cleaning water regulating tank for regulation.

7. The method for treating wastewater from the production of power battery structural parts according to claim 5 is characterized in that the membrane installed in the primary membrane pool is a tubular membrane, the secondary membrane pool and the tertiary membrane pool are both installed with nanofiltration membranes, the number of anaerobic tanks is 2, which are a primary UASB anaerobic tank and a secondary UASB anaerobic tank, the number of aerobic tanks is 6, and the 6 aerobic tanks are arranged in sequence, and the second sedimentation tank is an inclined tube sedimentation tank.

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