Polaroid pretreatment waste alkali liquor recovery method and equipment

Abstract

The invention provides a polaroid pretreatment waste alkali liquor recovery method and equipment, and the method comprises the following steps: carrying out multi-stage filtration on polaroid manufacturing pretreatment waste alkali liquor to remove suspended particulate matters; decomposing total organic carbon in the polarizer manufacturing pretreatment waste alkali liquid through UV light to generate an intermediate liquid containing sodium carbonate; adding calcium oxide into the intermediate liquid to generate calcium hydroxide, and reacting the calcium hydroxide with sodium carbonate in the intermediate liquid to generate calcium carbonate precipitate and sodium hydroxide; carrying out centrifugal separation on the calcium carbonate precipitate to obtain a clear liquid containing sodium hydroxide; and finally filtering the clear liquid through a precision filtering device to obtain regenerated alkali liquor meeting the recovery standard. According to the method, a traditional sulfuric acid neutralization method is abandoned, and the waste lye is treated by adopting a combined process of UV photolysis, chemical carbonate removal, precise filtration and the like, so that the waste lye can be reused.

Description

Technical Field

[0001] This invention relates to the field of polarizer production technology, and in particular to a method and equipment for recovering waste alkaline solution from polarizer pretreatment. Background Technology

[0002] In the polarizer manufacturing process, each production line generates 30 m³ of pretreatment waste alkaline solution per month. Currently, the waste alkaline solution used for polarizer pretreatment contains small organic molecules that are difficult to degrade, such as cellulose triacetate (TAC). The industry generally treats it with sulfuric acid for neutralization before discharge. This not only results in high treatment costs, but also makes it difficult to completely remove sulfate ions and small organic molecules from the treated water. As a result, the COD and conductivity of the wastewater do not meet the standards for reuse, and it can only be discharged as wastewater. There is still a need to develop a treatment scheme for polarizer waste alkaline solution that can purify the pretreatment waste alkaline solution from polarizer manufacturing into a reusable alkaline solution and achieve zero wastewater discharge.

[0003] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0004] This invention provides a method and equipment for recovering waste alkaline solution from polarizer pretreatment, aiming to solve the technical problems mentioned in the background section of the prior art.

[0005] The contents of this invention are as follows: The first aspect of this invention provides a method for recovering waste alkaline solution from polarizer pretreatment, comprising: The pretreatment waste alkaline solution from polarizer manufacturing is filtered through multiple stages to remove suspended particulate matter. The total organic carbon in the pretreated waste alkaline solution is decomposed by UV light to produce an intermediate solution containing sodium carbonate. Calcium oxide is added to the intermediate solution to generate calcium hydroxide, which reacts with sodium carbonate in the intermediate solution to generate calcium carbonate precipitate and sodium hydroxide. After separating the calcium carbonate precipitate by centrifugation, a clear liquid containing sodium hydroxide is obtained; The clarified liquid is then filtered through a precision filtration device to obtain a regenerated alkali solution that meets recycling standards.

[0006] In an optional embodiment of the first aspect of the present invention, the step of decomposing the total organic carbon in the pretreated waste alkaline solution of the polarizer by UV light includes: Hydrogen peroxide is added to the filtered pretreatment waste alkaline solution of the polarizer manufacturing process, and dual-wavelength ultraviolet light is used for synergistic irradiation to mineralize and decompose the total organic carbon in the pretreatment waste alkaline solution of the polarizer manufacturing process through advanced oxidation reaction. The dual-wavelength ultraviolet light includes vacuum ultraviolet band and deep ultraviolet band.

[0007] In an optional embodiment of the first aspect of the present invention, the step of decomposing the total organic carbon in the pretreated waste alkaline solution of the polarizer by UV light further includes: The total organic carbon concentration in the pretreatment waste alkaline solution of the polarizer manufacturing after the advanced oxidation reaction is monitored in real time by setting an online TOC analyzer, and the dosage of hydrogen peroxide and the irradiation power of the dual-wavelength ultraviolet light are automatically adjusted by a PID feedback control algorithm.

[0008] In an optional embodiment of the first aspect of the present invention, the multi-stage filtration includes a primary bag filter, a secondary precision filter, and a tertiary ultrafiltration. The secondary precision filter has a filtration level of micron, and the tertiary ultrafiltration uses a hollow fiber ultrafiltration membrane made of polyvinylidene fluoride and integrates an automated backwashing function based on transmembrane pressure difference monitoring.

[0009] In an optional embodiment of the first aspect of the present invention, the precision filtration device is a regenerable filtration device, which employs alkali-resistant ceramic membrane filtration or metal sintered filter element filtration and is equipped with an automatic backwashing function.

[0010] A second aspect of the present invention provides a device for recovering waste alkaline solution from polarizer pretreatment, comprising: Pretreatment device, including multi-stage filtration components; The UV photolysis device includes an ultraviolet reactor connected to the multi-stage filtration assembly; The chemical carbon removal device includes a reaction vessel connected to the outlet of the ultraviolet reactor and a calcium oxide dosing assembly connected to the reaction vessel. A solid-liquid separation device, including a centrifuge connected to the outlet of the reactor; A precision filtration device is connected to the clear liquid outlet of the centrifuge.

[0011] In an optional embodiment of the second aspect of the present invention, the UV photolysis device further includes a hydrogen peroxide dosing component, and the ultraviolet reactor includes a dual-wavelength ultraviolet irradiation component. The UV photolysis device is used to add hydrogen peroxide to the pretreatment waste alkaline solution of the polarizer manufacturing through the hydrogen peroxide dosing component, and to use the dual-wavelength ultraviolet irradiation component for synergistic irradiation to mineralize and decompose the total organic carbon in the pretreatment waste alkaline solution of the polarizer manufacturing through an advanced oxidation reaction.

[0012] In an optional embodiment of the second aspect of the present invention, the UV photolysis device further includes an online TOC analyzer, which is used to monitor the total organic carbon concentration in the pretreatment waste alkaline solution of the polarizer manufacturing after the advanced oxidation reaction in real time, and automatically adjust the dosage of the hydrogen peroxide dosing component and the irradiation power of the dual-wavelength ultraviolet irradiation component through a PID feedback control algorithm. The ultraviolet light emitted by the dual-wavelength ultraviolet irradiation component includes a vacuum ultraviolet band and a deep ultraviolet band.

[0013] In an optional embodiment of the second aspect of the present invention, the multi-stage filtration assembly includes a primary bag filter assembly, a secondary precision filter assembly, and a tertiary ultrafiltration assembly. The tertiary ultrafiltration assembly uses a hollow fiber ultrafiltration membrane made of polyvinylidene fluoride and integrates an automated backwashing pipeline based on transmembrane pressure differential monitoring.

[0014] In an optional embodiment of the second aspect of the present invention, the precision filtration device is a regenerable filtration device, which employs alkali-resistant ceramic membrane filtration or metal sintered filter cartridge filtration and is equipped with an automated backwashing pipeline.

[0015] Beneficial Effects: This invention provides a method and equipment for recovering waste alkaline solution from polarizer pretreatment. The method includes passing the waste alkaline solution from polarizer manufacturing pretreatment through multi-stage filtration to remove suspended particulate matter; decomposing the total organic carbon in the waste alkaline solution using UV light to generate an intermediate liquid containing sodium carbonate; adding calcium oxide to the intermediate liquid to generate calcium hydroxide, which reacts with the sodium carbonate in the intermediate liquid to generate calcium carbonate precipitate and sodium hydroxide; separating the calcium carbonate precipitate by centrifugation to obtain a clear liquid containing sodium hydroxide; and finally filtering the clear liquid through a precision filtration device to obtain a regenerated alkaline solution that meets recycling standards. This invention abandons the traditional sulfuric acid neutralization method and uses a combination of processes such as UV photolysis, chemical decarbonation, and precision filtration to treat the waste alkaline solution, allowing it to be reused. Attached Figure Description

[0016] Figure 1 This is a flowchart of a method for recovering waste alkaline solution from polarizer pretreatment according to the present invention.

[0017] Figure 2 This is a process diagram illustrating the recycling and reuse of waste alkaline solution from polarizer pretreatment according to the present invention.

[0018] Figure 3 This is a schematic diagram of a waste alkali solution recovery device for polarizer pretreatment according to the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of the invention.

[0020] See Figure 1 The first aspect of this invention provides a method for recovering waste alkaline solution from polarizer pretreatment, comprising: S100. The pretreatment waste alkaline solution from polarizer manufacturing is filtered through multiple stages to remove suspended particulate matter. In this invention, the pretreatment waste alkaline solution (mainly composed of NaOH, water, TAC small molecule organic matter, and suspended solids) generated during the polarizer manufacturing process is first collected in a raw liquid collection tank. Then, the pretreatment waste alkaline solution is pumped into a pretreatment device, which mainly consists of a three-stage filtration system, namely, the multi-stage filtration includes a primary bag filter, a secondary precision filter, and a tertiary ultrafiltration. Primary bag filtration: The pretreated waste alkaline liquid first enters the primary bag filter, which is filled with a high pH-resistant polypropylene (PP) filter bag with a pore size of 50μm to intercept larger suspended particles, colloids and other impurities in the waste liquid.

[0021] Secondary precision filtration: The waste alkaline solution after primary filtration enters the secondary precision filter, which is equipped with an alkali-resistant polyethersulfone (PES) pleated filter element with an absolute filtration accuracy of 1μm to further remove fine suspended particles.

[0022] Three-stage ultrafiltration: The waste alkaline solution after two-stage filtration is sent to the three-stage ultrafiltration module. For example, a hollow fiber ultrafiltration membrane made of polyvinylidene fluoride (PVDF) with a molecular weight cutoff of 20kDa can be selected (that is, the three-stage ultrafiltration uses a hollow fiber ultrafiltration membrane made of polyvinylidene fluoride). This ultrafiltration membrane can not only completely remove submicron particles, but also effectively intercept some large molecular organic particles.

[0023] In an optional embodiment of the present invention, to ensure stable system operation, the three-stage ultrafiltration module integrates an automated backwashing function. The automated backwashing function can monitor membrane fouling in real time through a transmembrane pressure differential (TMP) transmitter. When the pressure differential reaches a preset value (e.g., 0.15 MPa), the PLC controller automatically triggers the backwashing program, using a portion of the permeate water to backwash the membrane, effectively restoring membrane flux and extending its service life (i.e., the three-stage ultrafiltration also integrates an automated backwashing function based on transmembrane pressure differential monitoring).

[0024] S200: The total organic carbon in the pretreated waste alkaline solution is produced by decomposing the polarizer with UV light to generate an intermediate solution containing sodium carbonate. In step S200 of this invention, the UV photodecomposition technology can be implemented in various ways. For example, short-wavelength ultraviolet light can be used to decompose small organic carbon-containing molecules, or advanced oxidation technology (AOP) using UV / H2O2 can be employed. AOP technology abandons the traditional single UV photodecomposition, resulting in higher efficiency.

[0025] Taking the advanced oxidation technology (AOP) using UV / H2O2 as an example, in this invention, the step of decomposing the total organic carbon in the pretreatment waste alkaline solution of the polarizer manufacturing process by UV light to generate an intermediate solution containing sodium carbonate includes: adding hydrogen peroxide to the filtered pretreatment waste alkaline solution of the polarizer manufacturing process, and using dual-wavelength ultraviolet light (including vacuum ultraviolet band and deep ultraviolet band) for synergistic irradiation, thereby mineralizing and decomposing the total organic carbon in the pretreatment waste alkaline solution of the polarizer manufacturing process through an advanced oxidation reaction to generate an intermediate solution containing sodium carbonate.

[0026] Specifically, in this invention, the pretreated and clear waste alkali liquid is injected into the pipeline with a 30% H2O2 solution via a hydrogen peroxide (H2O2) dosing component and a metering pump before entering the ultraviolet reactor. Subsequently, the mixed liquid flows into the ultraviolet reactor, which is designed with a ring-shaped quartz sleeve. The reactor is equipped with dual-wavelength ultraviolet lamps of 185nm (VUV, vacuum ultraviolet) and 254nm (UVC, deep ultraviolet). The 254nm UV + H2O2 combination utilizes ultraviolet light to efficiently decompose H2O2 and generate hydroxyl radicals with extremely strong oxidizing power. The 185nm ultraviolet light has higher energy and can not only decompose H2O2 but also directly photolyze water molecules and organic molecules to generate hydroxyl radicals and other active free radicals. Under the excitation of dual-wavelength ultraviolet light, H2O2 decomposes to produce a large number of highly oxidizing hydroxyl radicals (OH). These radicals can non-selectively and completely mineralize the recalcitrant TAC organic molecules in the waste alkaline solution into CO2 and H2O. The generated CO2 reacts with NaOH in the liquid to produce sodium carbonate (Na2CO3) as a byproduct.

[0027] In an optional embodiment of the present invention, to achieve precise control and energy saving, an online TOC analyzer can be installed at the outlet of the ultraviolet reactor to monitor the TOC concentration in the treated liquid in real time. This data is transmitted to a PLC controller, which runs a PID algorithm to compare the measured value with the set target value (e.g., TOC < 10 mg / L) and automatically adjust the frequency of the H2O2 dosing pump and the output power of the UV lamp to ensure the treatment effect while avoiding waste of reagents and energy (i.e., the decomposition of the total organic carbon in the pretreated waste alkaline solution of the polarizer by UV light also includes: monitoring the total organic carbon concentration in the pretreated waste alkaline solution of the polarizer after the advanced oxidation reaction by setting an online TOC analyzer, and automatically adjusting the amount of hydrogen peroxide added and the irradiation power of the dual-wavelength ultraviolet light through a PID feedback control algorithm).

[0028] S300. Calcium oxide is added to the intermediate solution to generate calcium hydroxide, which reacts with sodium carbonate in the intermediate solution to generate calcium carbonate precipitate and sodium hydroxide. In this invention, the addition of calcium oxide to the intermediate solution first reacts with water in the intermediate solution to generate calcium hydroxide, and the calcium hydroxide then reacts with sodium carbonate to generate calcium carbonate precipitate, thereby removing carbonate ions from the intermediate solution.

[0029] In another optional embodiment of the present invention, the calcium oxide can also be replaced by calcium hydroxide slurry, that is, a pre-prepared calcium hydroxide slurry is directly added to the intermediate liquid to react with the sodium carbonate in the intermediate liquid to generate calcium carbonate precipitate and sodium hydroxide. In this embodiment of the present invention, calcium oxide (CaO) and water can be mixed and matured in a certain proportion to prepare a uniform calcium hydroxide (Ca(OH)2) slurry. An online carbonate ion selective electrode is installed on the inlet pipe of the reactor to measure the concentration of sodium carbonate in the liquid in real time. The sodium carbonate concentration data is used for feedforward control. The PLC controller calculates the amount of lime slurry to be added based on the sodium carbonate concentration data and controls the metering pump to add it to ensure that the stoichiometric ratio of the chemical reaction: Ca(OH)2 + Na2CO3 → CaCO3↓ + 2NaOH is optimized.

[0030] In the example of adding calcium oxide or using calcium hydroxide slurry in this invention, the inside of the reactor can also be equipped with a variable frequency speed-regulating turbine stirrer. The PLC controller can adjust the stirring speed according to the reaction stage to enhance the mixing and mass transfer efficiency, promote the growth of calcium carbonate (CaCO3) crystals, and make them form large particles that are easy to settle.

[0031] Taking the addition of calcium hydroxide slurry as an example, in this invention, the specific method of adjusting the stirring speed according to the reaction stage can be as follows: When starting the addition, the PLC controls the slurry pump to start, and the pre-prepared 15% Ca(OH)2 slurry is added at 80% of the maximum flow rate. At the same time, the PLC controller increases the speed of the stirrer to a high speed of 300 RPM. The purpose is to ensure that the viscous slurry can be quickly dispersed and evenly distributed as soon as it enters the reactor, to prevent local agglomeration and maximize the reaction contact area. The PLC continuously monitors the change in conductivity inside the reactor in seconds.

[0032] After the slurry addition is stopped (as the reaction proceeds, the total conductivity of the solution will continue to rise. When Na2CO3 is basically exhausted, the newly added Ca(OH)2 will no longer react, and the rate of increase in conductivity will slow down sharply and tend to stabilize. The PLC program sets a threshold for the rate of change in conductivity. Once the PLC detects that the average rate of change in conductivity is lower than this threshold for 2 consecutive minutes, it is determined that the reaction has reached its endpoint, and the PLC immediately stops the operation of the slurry pump), the PLC controller immediately reduces the speed of the stirrer to a medium-low speed of 80 RPM and maintains this speed for stirring for 20 minutes. This process is called crystal maturation or aging. The lower shear force helps the dissolution of small CaCO3 crystals and the growth of larger crystals, forming denser, larger, and more regular particles, which greatly benefits the subsequent centrifugal separation. After the reaction is completed, stirring is stopped, and the PLC controller completely stops the stirrer.

[0033] S400. After separating the calcium carbonate precipitate by centrifugation, a clear liquid containing sodium hydroxide is obtained.

[0034] In this invention, after the reaction in step S300 is completed, the intermediate liquid containing calcium carbonate precipitate is pumped into a solid-liquid separation device (e.g., a horizontal screw discharge centrifuge). The solid-liquid separation device can continuously and efficiently separate the solid phase calcium carbonate from the liquid phase containing sodium hydroxide. The separated sodium hydroxide-containing clear liquid flows into the next processing unit through the upper outlet, while the separated solid phase calcium carbonate filter cake is discharged from the slag discharge port through a screw conveyor. In order to realize the resource utilization of solid waste, the discharged filter cake is sent to a plate and frame filter press for deep dehydration, reducing its moisture content to below 30%. The obtained calcium carbonate cake can be further sold as a building material auxiliary material or industrial filler, improving the economy and environmental protection of the entire process.

[0035] S500. The clarified liquid is finally filtered through a precision filtration device to obtain a regenerated alkali solution that meets the recycling standards. In this invention, the precision filtration device can be a regenerable filtration device, which uses an alkali-resistant ceramic membrane filter or a sintered metal filter element filter and is equipped with an automatic backwashing function.

[0036] Taking the alkali-resistant ceramic membrane filter as an example, the alkali-resistant ceramic membrane has excellent chemical stability and mechanical strength, and its lifespan far exceeds that of traditional filter cartridges. Furthermore, the filtration accuracy of the alkali-resistant ceramic membrane filter can be 0.1μm, which can effectively intercept extremely fine particles that may escape during centrifugal separation. Using the alkali-resistant ceramic membrane filter can further ensure the purity of the recycled alkali solution. The alkali-resistant ceramic membrane filter is equipped with an automatic backwashing function. The PLC controller can be set according to the running time or pressure difference to periodically start compressed air to perform reverse pulse purging and flushing of the ceramic membrane, remove surface contaminants, and maintain the long-term stable filtration performance of the system.

[0037] In this invention, after the clear liquid is filtered by a precision filtration device, the final regenerated alkali solution will have a COD of less than 50 mg / L and a suspended solids (SS) of less than 20 mg / L, thus fully meeting the reuse standards of the polarizer production line pretreatment process. The regenerated alkali solution is collected in the finished product storage tank and is ready to be reused in production at any time.

[0038] To better achieve automated processing, all the processing equipment used in the polarizer pretreatment waste alkali recovery method of this invention can be centrally monitored and automatically controlled through PLC and touch screen human-machine interface, thereby realizing unattended operation of the entire process.

[0039] In summary, the main process flow of the polarizer pretreatment waste alkali solution recovery method of this invention can be as follows: Figure 2 As shown: 1. Wastewater pretreatment (collecting the pretreatment alkaline solution from polarizer manufacturing into a collection tank for pretreatment): After three-stage filtration to remove suspended particulate matter, the wastewater enters the raw water intermediate tank; 2. TOC removal process: using UV ultraviolet light technology to decompose small molecules of organic carbonaceous matter; 3. Chemical removal of carbonate ions: adding CaO (or Ca(OH)2) to remove carbonate ions from the wastewater, Ca(OH)2 + Na2CO3 = CaCO3 + 2NaOH; 4. Centrifugal separation process: separating CaCO3 by centrifugation; 5. Precision filtration process: after fine filtration with a 0.1µm filter element, the wastewater can be reused as pretreatment alkaline solution.

[0040] This invention, through the organic combination of multi-stage filtration, UV oxidation decomposition, chemical precipitation, efficient solid-liquid separation, and precision filtration, not only completely solves the problem of treating waste alkaline solution from polarizers, achieving closed-loop circulation of alkaline solution and zero discharge of wastewater, but also demonstrates outstanding economic and environmental benefits through intelligent control and solid waste resource utilization.

[0041] See Figure 3 The second aspect of the present invention provides a device for recovering waste alkaline solution from polarizer pretreatment, comprising: Pretreatment device 10 includes a multi-stage filtration assembly; UV photolysis device 20 includes an ultraviolet light reactor connected to the multi-stage filtration assembly; The chemical decarbonization device 30 includes a reaction vessel connected to the outlet of the ultraviolet reactor and a calcium oxide dosing assembly connected to the reaction vessel. Solid-liquid separation device 40 includes a centrifuge connected to the outlet of the reactor; A precision filter device 50 is connected to the clear liquid outlet of the centrifuge.

[0042] In an optional embodiment of the second aspect of the present invention, the multi-stage filtration assembly includes a primary bag filter assembly, a secondary precision filter assembly, and a tertiary ultrafiltration assembly. The tertiary ultrafiltration assembly uses a hollow fiber ultrafiltration membrane made of polyvinylidene fluoride and integrates an automated backwashing pipeline based on transmembrane pressure differential monitoring.

[0043] In an optional embodiment of the second aspect of the present invention, the UV photolysis device 20 further includes a hydrogen peroxide dosing component, and the ultraviolet reactor includes a dual-wavelength ultraviolet irradiation component. The UV photolysis device is used to add hydrogen peroxide to the pretreatment waste alkaline solution of the polarizer manufacturing through the hydrogen peroxide dosing component, and to use the dual-wavelength ultraviolet irradiation component for synergistic irradiation to mineralize and decompose the total organic carbon in the pretreatment waste alkaline solution of the polarizer manufacturing through an advanced oxidation reaction.

[0044] In an optional embodiment of the second aspect of the present invention, the UV photolysis device 20 further includes an online TOC analyzer. The online TOC analyzer is used to monitor the total organic carbon concentration in the pretreatment waste alkaline solution of the polarizer manufacturing after the advanced oxidation reaction in real time, and automatically adjusts the dosage of the hydrogen peroxide dosing component and the irradiation power of the dual-wavelength ultraviolet irradiation component through a PID feedback control algorithm. The ultraviolet light emitted by the dual-wavelength ultraviolet irradiation component includes a vacuum ultraviolet band and a deep ultraviolet band.

[0045] In an optional embodiment of the second aspect of the present invention, the precision filtration device 50 is a regenerable filtration device, which employs alkali-resistant ceramic membrane filtration or metal sintered filter cartridge filtration and is equipped with an automated backwashing pipeline.

[0046] In an optional embodiment of the second aspect of the present invention, the solid phase outlet of the centrifuge is connected to a filter press, which is used to perform deep dehydration and resource recovery treatment on the separated calcium carbonate precipitate.

[0047] In summary, this invention provides a method and equipment for recovering waste alkaline solution from polarizer pretreatment. The method includes passing the waste alkaline solution from polarizer manufacturing pretreatment through multi-stage filtration to remove suspended particulate matter; decomposing the total organic carbon in the waste alkaline solution from polarizer manufacturing pretreatment using UV light to generate an intermediate liquid containing sodium carbonate; adding calcium oxide to the intermediate liquid to generate calcium hydroxide, which reacts with the sodium carbonate in the intermediate liquid to generate calcium carbonate precipitate and sodium hydroxide; separating the calcium carbonate precipitate by centrifugation to obtain a clear liquid containing sodium hydroxide; and finally filtering the clear liquid through a precision filtration device to obtain a regenerated alkaline solution that meets recycling standards. This invention abandons the traditional sulfuric acid neutralization method and uses a combination of processes such as UV photolysis + chemical decarbonation + precision filtration to treat the waste alkaline solution, enabling the waste alkaline solution to be reused.

[0048] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for recovering waste alkaline solution from polarizer pretreatment, characterized in that, include: The pretreatment waste alkaline solution from polarizer manufacturing is filtered through multiple stages to remove suspended particulate matter. The total organic carbon in the pretreated waste alkaline solution is decomposed by UV light to produce an intermediate solution containing sodium carbonate. Calcium oxide is added to the intermediate solution to generate calcium hydroxide, which reacts with sodium carbonate in the intermediate solution to generate calcium carbonate precipitate and sodium hydroxide. After separating the calcium carbonate precipitate by centrifugation, a clear liquid containing sodium hydroxide is obtained; The clarified liquid is then filtered through a precision filtration device to obtain a regenerated alkali solution that meets recycling standards.

2. The method for recovering waste alkaline solution from polarizer pretreatment according to claim 1, characterized in that, The total organic carbon in the pretreated waste alkaline solution produced by decomposing the polarizer with UV light includes: Hydrogen peroxide is added to the filtered pretreatment waste alkaline solution of the polarizer manufacturing process, and dual-wavelength ultraviolet light is used for synergistic irradiation to mineralize and decompose the total organic carbon in the pretreatment waste alkaline solution of the polarizer manufacturing process through advanced oxidation reaction. The dual-wavelength ultraviolet light includes vacuum ultraviolet band and deep ultraviolet band.

3. The method for recovering waste alkaline solution from polarizer pretreatment according to claim 2, characterized in that, The method of decomposing the total organic carbon in the pretreated waste alkaline solution of the polarizer using UV light also includes: The total organic carbon concentration in the pretreatment waste alkaline solution of the polarizer manufacturing after the advanced oxidation reaction is monitored in real time by setting an online TOC analyzer, and the dosage of hydrogen peroxide and the irradiation power of the dual-wavelength ultraviolet light are automatically adjusted by a PID feedback control algorithm.

4. The method for recovering waste alkaline solution from polarizer pretreatment according to claim 1, characterized in that, The multi-stage filtration includes a primary bag filter, a secondary precision filter, and a tertiary ultrafiltration. The secondary precision filter has a filtration level of micron, and the tertiary ultrafiltration uses a hollow fiber ultrafiltration membrane made of polyvinylidene fluoride and integrates an automated backwashing function based on transmembrane pressure difference monitoring.

5. The method for recovering waste alkaline solution from polarizer pretreatment according to claim 1, characterized in that, The precision filtration device is a regenerable filtration device, which uses alkali-resistant ceramic membrane filtration or metal sintered filter element filtration and is equipped with an automatic backwashing function.

6. A device for recovering waste alkaline solution from polarizer pretreatment, characterized in that, include: Pretreatment device, including multi-stage filtration components; The UV photolysis device includes an ultraviolet reactor connected to the multi-stage filtration assembly; The chemical carbon removal device includes a reaction vessel connected to the outlet of the ultraviolet reactor and a calcium oxide dosing assembly connected to the reaction vessel. A solid-liquid separation device, including a centrifuge connected to the outlet of the reactor; A precision filtration device is connected to the clear liquid outlet of the centrifuge.

7. The polarizer pretreatment waste alkali solution recovery equipment according to claim 6, characterized in that, The UV photolysis device further includes a hydrogen peroxide dosing component, and the ultraviolet reactor includes a dual-wavelength ultraviolet irradiation component. The UV photolysis device is used to add hydrogen peroxide to the pretreatment waste alkaline solution of the polarizer manufacturing through the hydrogen peroxide dosing component, and to use the dual-wavelength ultraviolet irradiation component for synergistic irradiation to mineralize and decompose the total organic carbon in the pretreatment waste alkaline solution of the polarizer manufacturing through advanced oxidation reaction.

8. The polarizer pretreatment waste alkali solution recovery equipment according to claim 7, characterized in that, The UV photolysis device also includes an online TOC analyzer, which is used to monitor the total organic carbon concentration in the pretreatment waste alkaline solution of the polarizer manufacturing after the advanced oxidation reaction in real time, and automatically adjust the dosage of the hydrogen peroxide dosing component and the irradiation power of the dual-wavelength ultraviolet irradiation component through a PID feedback control algorithm. The ultraviolet light emitted by the dual-wavelength ultraviolet irradiation component includes the vacuum ultraviolet band and the deep ultraviolet band.

9. The polarizer pretreatment waste alkali solution recovery equipment according to claim 6, characterized in that, The multi-stage filtration assembly includes a primary bag filter assembly, a secondary precision filter assembly, and a tertiary ultrafiltration assembly. The tertiary ultrafiltration assembly uses a hollow fiber ultrafiltration membrane made of polyvinylidene fluoride and integrates an automated backwashing pipeline based on transmembrane pressure differential monitoring.

10. The polarizer pretreatment waste alkali solution recovery equipment according to claim 6, characterized in that, The precision filtration device is a regenerable filtration device, which uses alkali-resistant ceramic membrane filtration or metal sintered filter element filtration and is equipped with an automated backwashing pipeline.

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