A process for PVDF recovery coupled with wastewater treatment

Abstract

The invention discloses a PVDF recovery coupled wastewater treatment process. Waste liquid generated during PVDF recovery flows through a membrane pool and a treatment pool in sequence. A first driving pump drives a first ultrafine bubble generator to work. Ultrafine bubbles are generated at the outlet of the first ultrafine bubble generator. The ultrafine bubbles absorb PVDF particles in the waste liquid and float upward. The waste liquid in the membrane pool passes through a filtering flat membrane and enters the treatment pool. During the process of the waste liquid flowing through the treatment pool, a second driving pump arranged in the treatment pool drives a second ultrafine bubble generator to work. Ozone is introduced into an air inlet of the second ultrafine bubble generator. Ultrafine bubbles containing ozone are generated at the outlet of the second ultrafine bubble generator. The wastewater is treated by ozone and hydroxyl radicals generated by the collapse of the ultrafine bubbles.

Description

Technical Field

[0001] The present invention specifically relates to a process for PVDF recovery coupled with wastewater treatment. Background Art

[0002] PVDF (polyvinylidene fluoride) is a highly non-reactive thermoplastic fluorinated polymer. It is soluble in strong polar solvents such as dimethylacetamide. It has excellent properties such as anti-aging, chemical resistance, weather resistance, and UV radiation resistance. It can be used as engineering plastics, used to make sealing rings, corrosion-resistant equipment, capacitors, and also used as coatings, insulation materials, and ion exchange membrane materials.

[0003] However, a large amount of waste liquid will be generated in the process of producing PVDF, and the waste liquid contains pollutants such as perfluorooctanoic acid and LAS, and also contains a large amount of PVDF. Due to the unique structural characteristics of polymer materials, the polymer materials in the wastewater can be recycled and processed into useful things for reuse, thereby reducing losses and improving utilization rates. At the same time, the pollutants in the waste liquid are toxic and harmful substances and cannot be directly discharged into the water body. They need to go through a wastewater treatment process and can only be discharged after meeting the standards. Under normal circumstances, PVDF is extremely difficult to aggregate. The existing treatment method for wastewater containing polymer materials mainly adds flocculating agents, removes the polymer materials after flocculation and precipitation, and then performs secondary treatment on the waste liquid. Since the polymer materials removed after the addition of the agent cannot be directly recycled, a process flow of drug removal is required. The present invention can use ultra-fine bubbles to simultaneously solve the problems of PVDF recovery and wastewater treatment, and the recovered PVDF can be directly reused. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a simple system to realize the purification treatment of PVDF production waste liquid and a process method for recovering PVDF contained in the waste liquid.

[0005] In order to solve the above technical problems, the present invention is solved by the following technical solutions: a PVDF recovery coupled wastewater treatment process, including a membrane pool and a treatment pool, wherein a first ultrafine bubble generator and a filter flat membrane are arranged in the membrane pool, and the outlet of the ultrafine bubble generator is located below the filter flat membrane, and a second ultrafine bubble generator is arranged in the treatment pool, and the air inlet of the second ultrafine bubble generator is connected to an ozone generator; the waste liquid generated when producing PVDF flows through the membrane pool and the treatment pool in sequence, and the first ultrafine bubble generator is driven to work by a first driving pump, and the air inlet of the first ultrafine bubble generator is connected to air, and the first ultrafine bubble generator is connected to air. Ultrafine bubbles are generated at the outlet of the generator. The surface of the ultrafine bubbles is negatively charged, and the zeta potential of the bubbles is as high as -40mv~-100mv. The bubbles can absorb large PVDF particles in the waste liquid and float upward, so that they can be fished out for recycling. The waste liquid in the membrane pool passes through the filtering flat membrane and enters the treatment pool. The waste liquid flows into the treatment pool, and a second driving pump arranged in the treatment pool drives the second ultrafine bubble generator to work. The air inlet of the second ultrafine bubble generator is connected to the ozone generator. Ultrafine bubbles containing ozone are generated at the outlet of the second ultrafine bubble generator. The pollutants are removed and wastewater treatment is achieved through ozone and hydroxyl radicals generated by the crushing of the ultrafine bubbles.

[0006] Furthermore, the membrane pool is provided with a filter press system, and the filter press system filters the waste liquid in the membrane pool, and the filtered waste liquid enters the treatment pool, and the retained PVDF small particles are recycled; the advantage is that the waste liquid in the membrane pool can be secondary filtered by the filter press system, that is, the large PVDF particles in the waste liquid are floated upward by the ultrafine bubbles generated in the membrane pool, and then secondary filtration is performed through the filter press system to improve the recovery of PVDF.

[0007] Furthermore, the first ultrafine bubble generator is provided with a driving end, and the driving end is connected to the first driving pump. The first driving pump is located at the bottom of the membrane pool and is used to pass the waste liquid into the first ultrafine bubble generator. Negative pressure and vortex flow are generated inside the generator, and the air outside the air inlet is sucked into the inside. Under the cutting action of the vortex flow, a large number of bubbles with a diameter of 20-30 microns are discharged. Under the action of the internal pressure of the bubbles, the bubbles are quickly reduced to less than 1000 nanometers to form ultrafine bubbles. The advantage is that the waste liquid at the bottom of the membrane pool can be mixed and flowed by the first driving pump, thereby improving the balanced performance of PVDF in the waste liquid, thereby ensuring that the ultrafine bubbles can float the PVDF in the waste liquid upward and improve the recovery efficiency.

[0008] Furthermore, the flat filter membrane and the ultrafine bubble generating system are arranged in the same membrane pool. The advantage is that the ultrafine bubbles attached to the surface of the flat membrane can prevent the flat membrane from being clogged, making the flat membrane work more smoothly, reducing the number of backwashing times of the flat membrane, and greatly saving time costs.

[0009] Furthermore, the second ultrafine bubble generator is provided with a driving end, and the driving end is connected to a second driving pump. The second driving pump is located at the bottom of the membrane pool and is used to pump the waste liquid into the second ultrafine bubble generator and mix it with the ozone introduced into the air inlet, and then discharge the ultrafine bubbles containing ozone from the outlet; the advantage is that the second ultrafine bubble generator can generate ultrafine bubbles containing ozone, thereby utilizing ozone and hydroxyl radicals to oxidize the waste liquid, thereby improving the waste liquid treatment efficiency.

[0010] Furthermore, the diameter of the ultrafine bubbles is less than 1000 nanometers.

[0011] Compared with the prior art, the present invention has the following beneficial effects: by arranging the first ultrafine bubble generator and the filtering flat membrane in the same membrane pool, the space occupied by the equipment can be effectively reduced; at the same time, the ultrafine bubbles generated by the first ultrafine bubble generator are attached to the surface of the flat membrane to prevent the flat membrane from being blocked, making the flat membrane work more smoothly, reducing the number of backwashing times of the flat membrane, and greatly saving time costs; the ultrafine bubbles can also float large particles of PVDF upward for collection, and the recycled PVDF does not need to be added with drugs, saving the company's operating costs. At the same time, the ultrafine bubbles in the membrane pool are crushed to produce hydroxyl radicals to remove pollutants and achieve preliminary treatment of wastewater. At the same time, ozone is introduced into the second ultrafine bubble generator in the treatment pool to produce a large number of ultrafine bubbles containing ozone, thereby achieving further treatment of the waste liquid, recycling of PVDF and treatment of the waste liquid. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0013] Figure 1 This is a schematic diagram of the structure of Embodiment 1 of the present invention;

[0014] Figure 2 This is a structural diagram of Embodiment 2 of the present invention.

[0015] Figure 3 It is a process flow chart of the present invention. Implementation

[0016] The present invention is further described in detail below with reference to the accompanying drawings.

[0017] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art can think of other obvious variations. The basic principles of the present invention defined in the following description can be used for other embodiments, variations, improvements, equivalents, and other technical solutions that do not deviate from the spirit and scope of the present invention.

[0018] Those skilled in the art should understand that, in the disclosure of the present invention, the directions or positions indicated by the terms "longitudinal", "lateral", "up", "down", "left", "right", "front", "back", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. are based on the directions or positional relationships shown in the accompanying drawings, which are only simplified descriptions for the convenience of describing the present invention, and do not indicate or imply that the device or component referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, the above terms should not be understood as limitations on the present invention.

[0019] Embodiment 1, as attached Figure 1 and Figure 3 The process for PVDF recovery coupled with wastewater treatment shown in the figure comprises an air flotation tank 1, a membrane tank 2 and a treatment tank 3, wherein the PVDF waste liquid flows through the air flotation tank 1, the membrane tank 2 and the treatment tank 3 in sequence, wherein a first driving pump 4 and a first ultrafine bubble generator 5 are arranged in the air flotation tank 1, a filter flat membrane 8 is arranged in the membrane tank 2, and the first ultrafine bubble generator 5 is provided with a driving end, which is connected to the first driving pump 4, wherein the first driving pump 4 is located at the bottom of the membrane tank 2 and is used to pump the waste liquid into the first ultrafine bubble generator 5 and mix it with the air A introduced into the air inlet, and then discharge ultrafine bubbles with a diameter of less than 1000 nanometers from the outlet, wherein the surface of the ultrafine bubbles is negatively charged, and the zeta potential thereof is as high as -40mv~-100mv, and the waste liquid at the bottom of the membrane tank 2 can be made to flow by the arranged first driving pump 4, thereby improving the equilibrium performance of PVDF in the waste liquid, thereby ensuring that the ultrafine bubbles can float the PVDF in the waste liquid upward, and improving the recovery efficiency.

[0020] A second ultrafine bubble generator 7 is provided in the above-mentioned treatment pool 3, and ozone B is introduced into the air inlet of the second ultrafine bubble generator 7, wherein the second ultrafine bubble generator 7 is provided with a driving end, and the driving end is connected to the second driving pump 6. The second driving pump 6 is located at the bottom of the treatment pool 3 and is used to pump the waste liquid into the second ultrafine bubble generator 7 and mix it with the ozone introduced into the air inlet, and then discharge ultrafine bubbles containing ozone and with a diameter of less than 1000nm from the outlet. The second ultrafine bubble generator 7 can generate ultrafine bubbles containing ozone, thereby utilizing ozone and hydroxyl radicals to oxidize the waste liquid, thereby improving the waste liquid treatment efficiency.

[0021] The waste liquid generated during the production of PVDF flows sequentially through the flotation tank 1, the membrane tank 2 and the treatment tank 3. The first ultrafine bubble generator 5 in the flotation tank 1 is driven by the first driving pump 4 to work, and air is introduced into the air inlet of the first ultrafine bubble generator 5. Ultrafine bubbles are generated at the outlet of the first ultrafine bubble generator 5, and the ultrafine bubbles adsorb the PVDF particles in the waste liquid and float upward; the waste liquid in the membrane tank 2 passes through the filtering flat membrane 8 and enters the treatment tank 3; during the process of the waste liquid flowing through the treatment tank 3, the second driving pump 6 arranged in the treatment tank 3 drives the second ultrafine bubble generator 7 to work, ozone is introduced into the air inlet of the second ultrafine bubble generator 7, and ultrafine bubbles containing ozone are generated at the outlet of the second ultrafine bubble generator 7, and the wastewater is treated by ozone and hydroxyl free radicals generated by the collapse of the ultrafine bubbles.

[0022] Embodiment 2, as attached Figure 2 and Figure 3 A PVDF recovery coupled wastewater treatment process shown is improved in structure due to the problem of frequent clogging of the filter flat membrane in the membrane pool of Example 1. Specifically, it includes a membrane pool 2 and a treatment pool 3. A first ultrafine bubble generator 5 and a filter flat membrane 8 are arranged in the membrane pool 2. The outlet of the ultrafine bubble generator is located below the filter flat membrane 8. The first ultrafine bubble generator 5 is provided with a driving end, which is connected to a first driving pump 4. The first driving pump 4 is located at the bottom of the membrane pool 2 and is used to pump waste liquid into the first ultrafine bubble generator 5 and mix it with the air A introduced into the air inlet, and then discharge ultrafine bubbles from the outlet. The waste liquid at the bottom of the membrane pool 2 can be circulated by the set first driving pump 4, thereby improving the balance performance of PVDF in the waste liquid, thereby ensuring that the ultrafine bubbles can float the PVDF in the waste liquid upward and improve the recovery efficiency.

[0023] A second ultrafine bubble generator 7 is arranged in the above-mentioned treatment pool 3, and ozone B is introduced into the air inlet of the second ultrafine bubble generator 7. The second ultrafine bubble generator 7 is also provided with a driving end, and the driving end is connected to the second driving pump 6. The second driving pump 6 is located at the bottom of the membrane pool 2 and is used to pump the waste liquid into the second ultrafine bubble generator 7 and mix it with the ozone introduced into the air inlet, and then discharge ultrafine bubbles containing ozone and with a diameter of less than 1000nm from the outlet. The surface of the ultrafine bubbles is negatively charged, and its zeta potential is as high as -40mv~-100mv. The second ultrafine bubble generator 7 can generate ultrafine bubbles containing ozone, thereby utilizing ozone and hydroxyl radicals to oxidize the waste liquid and improve the waste liquid treatment efficiency.

[0024] The waste liquid generated during the production of PVDF flows through the membrane pool 2 and the treatment pool 3 in sequence, and the first ultrafine bubble generator 5 is driven to work by the first driving pump 4, and air is introduced into the air inlet of the first ultrafine bubble generator 5. A large number of ultrafine bubbles with a diameter of less than 1000nm are generated at the outlet of the first ultrafine bubble generator 5, and the ultrafine bubbles adsorb the PVDF particles in the waste liquid and float upward. In the process of the first ultrafine bubble generator 5 generating ultrafine bubbles, some of the ultrafine bubbles will be crushed and ruptured. At the moment of ultrafine bubble rupture, due to the drastic change of the disappearance of the gas-liquid interface, the high-concentration ions gathered on the interface will release the accumulated chemical energy, which can produce a large number of hydroxyl free radicals, and the hydroxyl free radicals can perform preliminary purification treatment on the waste liquid in the membrane pool 2.

[0025] The waste liquid in the membrane pool 2 enters the treatment pool 3 after passing through the filtering flat membrane 8; in the process of the waste liquid flowing through the treatment pool 3, the second driving pump 6 arranged in the treatment pool 3 drives the second ultrafine bubble generator 7 to work, and ozone is introduced into the air inlet of the second ultrafine bubble generator 7. Ultrafine bubbles containing ozone are generated at the outlet of the second ultrafine bubble generator 7, and the wastewater is treated by ozone and hydroxyl radicals generated by the collapse of ultrafine bubbles.

[0026] Furthermore, in order to recover the small PVDF particles that are not removed by air flotation in the membrane pool, a filter press system is provided in the membrane pool 2, and the filter press system filters the waste liquid in the membrane pool 2, and the filtered waste liquid enters the treatment pool 3. The waste liquid in the membrane pool 2 can be filtered twice by the filter press system, that is, the PVDF in the waste liquid is floated upward by the ultrafine bubbles generated in the membrane pool 2, and then the recovery rate of PVDF is improved by secondary filtration through the filter press system.

[0027] The first ultrafine bubble generator 5 and the filter flat membrane 8 provided by the present invention are located in the same membrane pool 2, which can effectively reduce the space occupied by the equipment. At the same time, the ultrafine bubbles generated by the first ultrafine bubble generator 5 can float large particles of PVDF upward for collection, thereby reducing the possibility of clogging of the filter flat membrane 8. At the same time, the ultrafine bubbles will generate hydroxyl radicals at the moment of rupture, which have an oxidizing effect and react with harmful substances in the waste liquid to achieve harmless treatment of the waste liquid. At the same time, ozone is introduced into the second ultrafine bubble generator 7 in the treatment pool 3 to generate a large number of ultrafine bubbles containing ozone, thereby further achieving the treatment of the waste liquid, and realizing the recycling and utilization of PVDF and the treatment of the waste liquid.

[0028] Those skilled in the art should understand that the embodiments of the present invention described above and shown in the accompanying drawings are only examples and do not limit the present invention. The purpose of the present invention has been fully and effectively achieved. The functions and structural principles of the present invention have been demonstrated and explained in the embodiments, and the embodiments of the present invention may be deformed or modified in any way without departing from the principles.

Claims

1. A process for PVDF recovery coupled with wastewater treatment, characterized in that: The invention comprises a membrane pool and a treatment pool, wherein a first ultrafine bubble generator and a filtering flat membrane are arranged in the membrane pool, wherein the outlet of the first ultrafine bubble generator is located below the filtering flat membrane, wherein a second ultrafine bubble generator is arranged in the treatment pool, and the air inlet of the second ultrafine bubble generator is connected to an ozone generator; waste liquid generated when producing PVDF flows sequentially through the membrane pool and the treatment pool, the first ultrafine bubble generator is driven to work by a first driving pump, and the air inlet of the first ultrafine bubble generator is connected to air, ultrafine bubbles are generated at the outlet of the first ultrafine bubble generator, the surface of the ultrafine bubbles is negatively charged, and the zeta potential thereof is as high as -40mv to -100mv, and the ultrafine bubbles can be adsorbed and floated upwards in the waste liquid, so as to be easily fished out and recycled; the waste liquid in the membrane pool enters the treatment pool after passing through the filtering flat membrane; the waste liquid flows into the treatment pool, and the second driving pump arranged in the treatment pool drives the second ultrafine bubble generator to work, and the second The air inlet of the ultrafine bubble generator is connected to the ozone machine, and the outlet of the second ultrafine bubble generator generates ultrafine bubbles containing ozone. The hydroxyl free radicals generated by the crushing of the ozone ultrafine bubbles remove pollutants and realize wastewater treatment. The second ultrafine bubble generator is provided with a driving end, and the driving end is connected to the second driving pump. The second driving pump is located at the bottom of the treatment tank and is used to pass the waste liquid into the second ultrafine bubble generator. Negative pressure and vortex flow are generated inside the second ultrafine bubble generator, and the ozone generated by the ozone machine outside the air inlet is sucked into the interior, and a large number of bubbles with a diameter of 20-30 microns are discharged under the cutting action of the vortex flow. Under the action of the internal pressure of the bubbles, the bubbles are rapidly reduced to less than 1000 nanometers to form ozone ultrafine bubbles. The membrane pool is provided with a filter press system, and the filter press system filters the waste liquid in the membrane pool. The filtered waste liquid enters the treatment pool, and the filtered PVDF powder is recycled.

2. A PVDF recovery coupled wastewater treatment process according to claim 1, characterized in that: The first ultrafine bubble generator is provided with a driving end, and the driving end is connected to a first driving pump. The first driving pump is located at the bottom of the membrane pool and is used to pass the waste liquid into the first ultrafine bubble generator. Negative pressure and vortex flow are generated inside the first ultrafine bubble generator, and the air outside the air inlet is sucked into the interior. Under the cutting action of the vortex flow, a large number of bubbles with a diameter of 20-30 microns are discharged. Under the action of the internal pressure of the bubbles, the bubbles are rapidly reduced to below 1000 nanometers to form ultrafine bubbles.

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