A sustainable system process for removing perfluoro or polyfluoroalkyl substances

Abstract

The application discloses a kind of sustainable system processes for removing perfluoro or polyfluoroalkyl substance, belongs to water treatment field.The process is concentrated to foam phase by foam separation in water phase PFAS, combined with nanofiltration membrane system concentration PFAS containing solution, then carries out defluorination degradation by using hydrated electron in electrocatalytic unit;Nanofiltration water is treated by ion exchange resin, saturated resin is backwashed by mixed solution, and backwash waste liquid is regenerated and recycled by another electrocatalytic unit;Finally, harmless calcium fluoride is generated by flocculation and precipitation, and fluoride ion is removed.The process is suitable for various PFAS, can efficiently remove long-chain and short-chain PFAS, total removal rate is high, can cope with complex water quality, is suitable for drinking water, natural water body and industrial wastewater etc.Situations, and no secondary pollution, regeneration liquid can be recycled, realizes sustainable degradation.

Description

Technical Field

[0001] This invention belongs to the field of water treatment, and in particular relates to a sustainable system process for removing perfluorinated or polyfluoroalkyl substances. Background Technology

[0002] Per- and polyfluoroalkyl substances (PFAS) are a class of man-made chemicals widely used in industrial and consumer products. Due to their unique chemical structures, PFAS possess extremely high chemical stability and surface activity, making them widely used in the manufacture of waterproof, oil-proof, and stain-resistant products, such as fire-fighting foam, non-stick cookware coatings, food packaging, and textiles. However, these very properties make PFAS difficult to degrade in the environment, earning them the title of "permanent chemicals." With the large-scale production and use of PFAS, their harm to the environment and human health is becoming increasingly prominent. PFAS can enter the aquatic environment through various pathways, such as industrial wastewater discharge, landfill leachate, and runoff from fire training grounds. Once in water bodies, PFAS persist for extended periods and accumulate in organisms through biomagnification in the food chain, posing a serious threat to ecosystems and human health. Studies have shown that long-term exposure to PFAS may lead to various health problems, including impaired immune systems, thyroid disease, cancer, and reproductive and developmental abnormalities.

[0003] Currently, methods for removing PFAS from water mainly include fixed-bed adsorbents, ion exchange resins, membrane separation, and advanced oxidation / reduction processes. However, these traditional methods have many limitations. For example, activated carbon adsorption is effective for long-chain PFAS, but it is difficult to remove branched and short-chain compounds, and its adsorption capacity is limited. After adsorption saturation, it is difficult to regenerate, requiring frequent replacement and generating a large amount of solid waste, or even hazardous waste. Although ion exchange resins have a good removal effect on PFAS, conventional anion exchange resins cannot meet the requirements for high-efficiency removal, and regeneration is difficult, requiring modification, which increases operating costs. Moreover, the cleaning solution used for regeneration still contains a large amount of PFAS, causing secondary pollution. Although membrane separation methods have a high PFAS removal rate, they essentially transfer PFAS to the concentrated aqueous phase through physical methods, without achieving PFAS decomposition. At the same time, membrane systems also have disadvantages such as high operating energy consumption and susceptibility to irreversible fouling. Advanced oxidation / reduction technologies, such as photocatalysis and electrocatalysis, can degrade PFAS, but they have stringent requirements for the reaction medium and may generate secondary pollution. To address the shortcomings of the aforementioned processes, developing a sustainable and thorough water treatment process that degrades PFAS, is cost-effective, and produces no secondary pollution is of significant practical importance. Summary of the Invention

[0004] To address the problems of traditional methods failing to remove branched and short-chain compounds, conventional resins being unable to meet anion exchange requirements, and the potential for secondary pollution.

[0005] To address the above problems, the present invention provides the following technical solution:

[0006] A sustainable system process for removing perfluorinated or polyfluoroalkyl substances includes the following steps:

[0007] S1: The mixture is passed through a foam separator. Under the action of aeration and surfactant, the PFAS in the aqueous phase is coated into the top foam phase, and then the top foam phase is introduced into the electrocatalytic unit 1 for reaction.

[0008] S2: The PFAS-containing concentrate produced by the above foam phase and nanofiltration membrane system is reduced in electrocatalytic unit 1;

[0009] S3: The foam phase and the concentrated water of the membrane system are placed in the electrocatalytic unit 1 for reduction reaction. The hydrated electrons eaq- generated on the multilayer semiconductor cathode react with PFAS in the water to remove F element. At the same time, an oxidation reaction occurs on the anode to achieve complete degradation of PFAS.

[0010] S4: The permeate from electrocatalytic unit 1 enters the flocculation zone of the flocculation sedimentation tank, where it forms larger flocs under the action of Ca(OH)2 and PAM, and finally achieves solid-liquid separation in the sedimentation zone, ultimately obtaining permeate that meets the standards and harmless calcium fluoride.

[0011] S5: When the PFAS adsorbed by the ion exchange resin is saturated, it is backwashed and desorbed with a mixed solution of NaCl and NaOH. The backwash waste liquid enters the electrocatalytic unit 2 for regeneration. After the desorbed PFAS is defluorinated and degraded, the regenerated liquid can be reused.

[0012] S6: When the fluoride ions in the regenerated liquid are close to saturation, it is discharged into the flocculation sedimentation tank for flocculation sedimentation treatment to remove the F ions in the regenerated liquid.

[0013] Preferably, the PFAS in S1 includes perfluorooctane sulfonate, perfluorooctanoic acid, perfluoro-n-hexane sulfonate, perfluoro-nonanoic acid, perfluoro-decanoic acid, 6:2-fluoropolymer sulfonate compound, 8:2-fluoropolymer sulfonate compound, perfluoro-heptanoic acid, polyfluorinated carboxylic acid, alkyl sulfonate and alkyl sulfonamide compound.

[0014] Preferably, the foam separation unit in S1 includes a foam separation tower, an active agent dosing facility, an aeration facility, and a foam phase scraper separator.

[0015] Preferably, the nanofiltration membrane system unit in S2 includes a GE Osmonics antifouling tubular membrane module, a multi-media filter, an activated carbon filter, a pH adjustment system, a fluid control device, an inlet and outlet water conductivity meter, a backwashing system, and a PLC control system.

[0016] Preferably, the S2 membrane system operates with the following parameters: influent pH value controlled at 6-8, operating pressure at 10-20 bar, operating temperature controlled at 15-35℃, product water recovery rate controlled at 50-70%, and concentration factor at 5-10 times.

[0017] Preferably, the ion exchange resin system in S2 consists of two parallel ion exchange columns and the resin filled inside, an air backwashing aeration system, a regenerated liquid backwashing system, and a pipeline gate control system.

[0018] Preferably, the resin used in the ion exchange resin system in S2 is PFR-630N resin.

[0019] Preferably, the hydration electron electrocatalytic units 1 and 2 in S4 and S5 have the same structure, each including multiple sets of plate electrode electrolytic cells, a water inlet pump, a water inlet pipe, a water outlet pipe, electrodes, and a high-frequency power supply.

[0020] Preferably, the anode of the electrode assembly is a multi-layer titanium metal plate, and the cathode is a multilayer semiconductor special material plate. The distance between the two electrodes is 10-15 cm, the voltage is 15-20 V, and the current density is 10-30 mA / cm². 2 .

[0021] Preferably, the cathode plate uses a single-crystal silicon wafer as a substrate, on which a layer of SiO2 is grown, and then a layer of aluminum, bismuth or Rh metal elements is vapor-deposited on the surface.

[0022] The advantages and benefits of a sustainable system process for removing perfluorinated or polyfluoroalkyl substances according to the present invention:

[0023] 1. This patent achieves efficient enrichment and separation of long-chain and short-chain PFAS through a combination of processes such as foam separation and nanofiltration membrane concentration.

[0024] 2. This patent addresses the water quality characteristics of high salinity in the concentrated PFAS phase by employing a special hydrated electron electrocatalytic defluorination subsystem, which can achieve complete defluorination and degradation, overcoming the shortcomings of other PFAS degradation processes such as photocatalysis and advanced oxidation in high-salt environments where efficiency is low.

[0025] 3. In this patent, the amphiphilic PFAS, after being removed by foam separation pretreatment, can effectively control the fouling of nanofiltration membranes, extend the membrane's lifespan and operational stability; the selected nanofiltration membrane system has stronger fouling resistance and more stable operation compared to the reverse osmosis membrane system; the regeneration solution of the ion exchange system can be reused after defluorination treatment, without generating hazardous waste such as regeneration liquid; the F ions generated after defluorination and degradation of PFAS are converted into harmless calcium fluoride, without generating secondary pollution.

[0026] 4. This patent is applicable to PFAS of different concentrations and compositions, and can effectively cope with complex water quality conditions. It is suitable for many scenarios such as fluoride-containing drinking water, natural water bodies and industrial wastewater.

[0027] 5. This patent describes a water treatment process that uses a method to sustainably degrade PFAS in water without generating secondary pollution. Attached Figure Description

[0028] Figure 1 This is a process flow diagram of the PFAS sustainable degradation system in this invention. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0031] Example 1

[0032] This embodiment provides a sustainable system process for removing perfluorinated or polyfluoroalkyl compounds, suitable for electrolytic catalytic degradation, including the following implementation details:

[0033] Experimental objective:

[0034] The degradation of F element is achieved by utilizing the basic principle of electrolysis.

[0035] Experimental materials:

[0036] Foam separator, nanofiltration membrane system, ion exchange resin column, Ca(OH)2, NaCl, NaOH.

[0037] Experimental steps:

[0038] S1: The mixture is passed through a foam separator. Under the action of aeration and surfactant, the PFAS in the aqueous phase is coated into the top foam phase. Then, the foam phase is introduced into the electrocatalytic unit 1 for reaction through a scraper separator.

[0039] S2: The permeate from the foam separator enters the nanofiltration membrane system. The aqueous solution containing PFAS produced by the nanofiltration membrane system will enter the electrocatalytic unit 1 for reaction. Then, the permeate filtered by the nanofiltration membrane enters the ion exchange resin column. Samples are collected at 30 min, 60 min and 120 min respectively. After separation, an aqueous solution without PFAS will be obtained.

[0040] S3: The foam phase and the concentrated water of the membrane system are placed in the electrocatalytic unit 1 for reduction reaction. The hydrated electrons eaq- generated on the multilayer semiconductor cathode react with PFAS in the water to remove F element. At the same time, an oxidation reaction occurs on the anode to achieve complete degradation of PFAS.

[0041] S4: The permeate from electrocatalytic unit 1 enters the flocculation zone of the flocculation sedimentation tank, where it forms larger flocs under the action of Ca(OH)2 and PAM, and finally achieves solid-liquid separation in the sedimentation zone, ultimately obtaining permeate that meets the standards and harmless calcium fluoride.

[0042] S5: When the PFAS adsorbed by the ion exchange resin is saturated, it is backwashed and desorbed with a mixed solution of NaCl and NaOH. The backwash waste liquid enters the electrocatalytic unit 2 for regeneration. After the desorbed PFAS is defluorinated and degraded, the regenerated liquid can be reused.

[0043] S6: When the fluoride ions in the regenerated liquid are close to saturation, it is discharged into the flocculation sedimentation tank for flocculation sedimentation treatment to remove the F ions in the regenerated liquid.

[0044] Experimental results: See Table 1 for details.

[0045] Table 1: Test Results of Example 1

[0046] Adsorption capacity PFAS concentration in clear solution (μg / L) Total removal rate raw water - 5000.0 - After the foam separator - 3000.0 - Nanofiltration membrane concentrate - 15000.0 - Nanofiltration permeate - 200.0 - Ion exchange resin adsorption for 30 minutes 8.5 120.0 - Ion exchange resin adsorption for 60 min 15.2 50.0 - Ion exchange resin adsorption for 120 min 22.8 10.0 - After electrocatalytic unit 1 degrades - 1.5 - After treatment in flocculation sedimentation tank - 0.3 99.94% Ion exchange backwash regeneration solution - 800.0 - After regeneration of the electrocatalytic unit - 50.0 -

[0047] This embodiment presents a sustainable system process that combines foam separation, nanofiltration membrane system, electrocatalytic degradation, flocculation sedimentation, and ion exchange regeneration. This process successfully utilizes the electrolysis principle to achieve efficient degradation of phosphorus (F) in PFAS. The raw water PFAS concentration of 5000.0 μg / L was reduced to 3000.0 μg / L after treatment by the foam separator. The nanofiltration membrane system increased the concentrate concentration to 15000.0 μg / L and reduced the permeate concentration to 200.0 μg / L. Ion exchange resin adsorption was performed for 30 min, 60 min, and 120 min. At that time, the adsorption capacity reached 8.5 mg / g, 15.2 mg / g, and 22.8 mg / g, respectively, corresponding to a clear liquid concentration of 120.0 μg / L, 50.0 μg / L, and 10.0 μg / L. After degradation by electrocatalytic unit 1, the concentration dropped to 1.5 μg / L, and the final product water concentration after treatment in the flocculation sedimentation tank was only 0.3 μg / L, with a total removal rate of 99.94%, and harmless calcium fluoride was generated. The ion exchange resin backwash regeneration liquid was regenerated by electrocatalytic unit 2, and the concentration dropped to 50.0 μg / L, which can be recycled. After fluoride ion saturation, it is removed by flocculation sedimentation. The overall process has both high efficiency and sustainability.

[0048] Example 2

[0049] This embodiment provides a sustainable system process for removing perfluorinated or polyfluoroalkyl substances, employing conventional ion exchange resin adsorption, and includes the following implementation details:

[0050] Experimental objective:

[0051] To investigate the adsorption effect of traditional ion exchange resins on PFAS.

[0052] Experimental materials:

[0053] Foam separator, nanofiltration membrane system, traditional ion exchange resin column, Ca(OH)2, NaCl, NaOH.

[0054] Experimental steps:

[0055] S1: The mixture is passed through a foam separator. Under the action of aeration and surfactant, the PFAS in the aqueous phase is coated into the top foam phase. Then, the foam phase is introduced into the electrocatalytic unit 1 for reaction through a scraper separator.

[0056] S2: The permeate from the foam separator enters the nanofiltration membrane system. The PFAS-containing concentrate produced by the system enters the electrocatalytic unit 1 for reaction. Then, the permeate filtered by the nanofiltration membrane enters the ion exchange resin column. Samples are collected at 30 min, 60 min, and 120 min respectively. After separation, an aqueous solution without PFAS is obtained.

[0057] S3: The foam phase and the concentrated water of the membrane system are placed in the electrocatalytic unit 1 for reduction reaction. The hydrated electrons eaq- generated on the multilayer semiconductor cathode react with PFAS in the water to remove F element. At the same time, an oxidation reaction occurs on the anode to achieve complete degradation of PFAS.

[0058] S4: The permeate from electrocatalytic unit 1 enters the flocculation zone of the flocculation sedimentation tank, where it forms larger flocs under the action of Ca(OH)2 and PAM, and finally achieves solid-liquid separation in the sedimentation zone, ultimately obtaining permeate that meets the standards and harmless calcium fluoride.

[0059] S5: When the PFAS adsorbed by the ion exchange resin is saturated, it is backwashed and desorbed with a mixed solution of NaCl and NaOH. The backwash waste liquid enters the electrocatalytic unit 2 for regeneration. After the desorbed PFAS is defluorinated and degraded, the regenerated liquid can be reused.

[0060] S6: When the fluoride ions in the regenerated liquid are close to saturation, it is discharged into the flocculation sedimentation tank for flocculation sedimentation treatment to remove the F ions in the regenerated liquid.

[0061] Experimental results: See Table 1 for details.

[0062] Table 1: Test Results of Example 2

[0063] Adsorption capacity PFAS concentration in clear solution (μg / L) Total removal rate raw water - 5000.0 - After the foam separator - 3000.0 - Nanofiltration membrane concentrate - 15000.0 - Nanofiltration permeate - 200.0 - Ion exchange resin adsorption for 30 minutes 3.2 180.0 - Ion exchange resin adsorption for 60 min 7.5 100.0 - Ion exchange resin adsorption for 120 min 12.0 30.0 - After electrocatalytic unit 1 degrades - 3.0 - After treatment in flocculation sedimentation tank - 0.8 99.34% Ion exchange backwash regeneration solution - 600.0 - After regeneration of the electrocatalytic unit - 80.0 -

[0064] Example 2 employs a sustainable system process of traditional ion exchange resin adsorption, foam separation, nanofiltration membrane system, electrocatalytic degradation, flocculation precipitation, and ion exchange regeneration. The PFAS removal effect is as follows: the raw water PFAS concentration of 5000.0 μg / L is reduced to 3000.0 μg / L after treatment by the foam separator; the nanofiltration membrane system increases the concentrate concentration to 15000.0 μg / L and reduces the permeate concentration to 200.0 μg / L; and the adsorption capacity of traditional ion exchange resin after 30 min, 60 min, and 120 min is 3.2 mg / g, 7 mg / g, and 7 mg / g, respectively. 5 mg / g and 12.0 mg / g correspond to clear liquid concentrations reduced to 180.0 μg / L, 100.0 μg / L, and 30.0 μg / L, respectively. After degradation by electrocatalytic unit 1, the concentration is reduced to 3.0 μg / L. After treatment in the flocculation sedimentation tank, the final product water concentration is 0.8 μg / L, and the total removal rate of the system reaches 99.984%, generating harmless calcium fluoride. The ion exchange resin backwash regeneration liquid is regenerated by electrocatalytic unit 2, and its concentration is reduced to 80.0 μg / L, which can be recycled. After fluoride ion saturation, it is removed by flocculation sedimentation. The overall process demonstrates a certain removal effect and sustainability.

[0065] Comparative Example 1

[0066] This embodiment provides a method for activated carbon adsorption of perfluorinated and polyfluoroalkyl compounds, including the following implementation details:

[0067] Experimental objective:

[0068] Adsorption of long-chain PFAS by activated carbon

[0069] Experimental materials:

[0070] Granular activated carbon (GAC), perfluorinated and polyfluoroalkyl compounds, methanol, hydrochloric acid, sodium hydroxide, sodium chloride, calcium chloride, humic acid.

[0071] Experimental steps:

[0072] S1: Weigh a certain amount of PFAS and dissolve it in methanol solution, then dilute the solution with pure water, and finally adjust the pH to the appropriate target range with hydrochloric acid or sodium hydroxide.

[0073] S2: Add activated carbon to the PFAS solution and place it in a constant temperature shaker for 720 min. Take samples at 0, 5, 10, 20, 30, 60, 120, 180, 360 and 720 min respectively. Finally, take the supernatant and filter it through a 0.22 μm PP membrane.

[0074] S3: Add an equal amount of activated carbon to the sample solutions taken at different time intervals and shake until equilibrium is reached. After equilibrium, centrifuge and filter, detect the PFAS concentration in the supernatant, and finally calculate the equilibrium adsorption capacity and fit it with the Langmuir and Freundlich models.

[0075] Experimental results: See Table 2 for details.

[0076] Table 2: Test Results of Comparative Example 1

[0077] Adsorption capacity PFAS concentration in clear solution (μg / L) Average adsorption data 0min 0.00 20.00 - 5min 1.52 18.48 - 10min 2.85 17.15 - 20min 4.51 15.49 - 30min 6.03 13.97 - 60min 8.05 11.95 - 120min 10.12 9.88 - 180min 11.58 8.42 - 360min 12.56 7.44 - 720min 13.02 6.98 13.00

[0078] Comparative Example 1 used granular activated carbon to adsorb long-chain PFAS. The adsorption effect of activated carbon on long-chain PFAS was investigated by reacting PFAS solution with activated carbon in a constant-temperature shaker and taking samples at different time intervals. During the experiment, the adsorption capacity of activated carbon gradually increased with increasing reaction time, while the PFAS concentration in the supernatant decreased accordingly, finally reaching adsorption equilibrium at 720 minutes. This indicates that granular activated carbon has a certain adsorption capacity for long-chain PFAS, and its adsorption process follows a gradual stabilization pattern. The equilibrium adsorption characteristics can be analyzed by fitting relevant models.

[0079] Comparing Example 1, Example 2, and Comparative Example 1, it is evident that Example 1 exhibits superior treatment performance. Example 1 utilizes PFR-630N resin, achieving an adsorption capacity of 22.8 mg / g after 120 minutes, significantly higher than the 12.0 mg / g of the traditional ion exchange resin in Example 2. Furthermore, the PFAS concentration in the nanofiltration permeate after ion exchange treatment decreased to 10.0 μg / L, superior to the 30.0 μg / L in Example 2. After degradation and flocculation sedimentation in Electrocatalytic Unit 1, the final permeate concentration was only 0.3 μg / L, with a total system removal rate of 99.94%, slightly lower than the 99.34% in Example 2. However, the concentration of the ion exchange backwash regenerated liquid decreased to 50.0 μg / L after regeneration in Electrocatalytic Unit 2, demonstrating superior recycling performance and significantly better than the 80.0 μg / L after regeneration in Example 2. In contrast, Comparative Example 1, using activated carbon adsorption, only achieved an adsorption capacity of 13.02 mg / g after 720 minutes, with a final clarified liquid concentration of 6.98 μg / L. Furthermore, it failed to achieve complete degradation of PFAS and recycling of the regenerated liquid, resulting in significantly lower overall efficiency and sustainability compared to Example 1. In summary, Example 1 demonstrates superior performance in adsorption efficiency, final treatment effect, and regeneration recycling, making it a superior process for removing perfluorinated or polyfluoroalkyl substances.

[0080] Those skilled in the art will recognize that the modules and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0081] In addition, the functional modules in the various embodiments of this application can be integrated into one processing module, or each module can exist physically separately, or two or more modules can be integrated into one module.

[0082] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of protection of the claims.

[0083] In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included in the protection of the present invention.

Claims

1. A sustainable system process for removing perfluorinated or polyfluoroalkyl substances, characterized in that, Includes the following steps: S1: The mixture is passed through a foam separator. Under the action of aeration and surfactant, the PFAS in the aqueous phase is coated into the top foam phase. The top foam phase is then introduced into the electrocatalytic unit 1 for reaction. S2: The permeate from the foam separator enters the nanofiltration membrane system. The PFAS-containing concentrate produced by the nanofiltration membrane system enters the electrocatalytic unit 1 for reaction. The permeate filtered by the nanofiltration membrane then enters the ion exchange resin column. S3: The foam phase and the concentrated water of the nanofiltration membrane system are placed in the electrocatalytic unit 1 for reduction reaction. The hydrated electrons eaq- generated on the multilayer semiconductor cathode react with PFAS in the water to remove F element. At the same time, an oxidation reaction occurs on the anode to achieve complete degradation of PFAS. S4: The permeate from electrocatalytic unit 1 enters the flocculation zone of the flocculation sedimentation tank, where it forms larger flocs under the action of Ca(OH)2 and PAM, and finally achieves solid-liquid separation in the sedimentation zone, ultimately obtaining permeate and harmless calcium fluoride. S5: When the PFAS adsorbed by the ion exchange resin is saturated, it is backwashed and desorbed with a mixed solution of NaCl and NaOH. The backwash waste liquid enters the electrocatalytic unit 2 for regeneration. After the desorbed PFAS is defluorinated and degraded, the regenerated liquid can be reused. S6: When the fluoride ions in the regenerated liquid are close to saturation, it is discharged into the flocculation sedimentation tank for flocculation sedimentation treatment to remove the F ions in the regenerated liquid.

2. The sustainable system process for removing perfluorinated or polyfluoroalkyl substances as described in claim 1, characterized in that, The PFAS in S1 include perfluorooctane sulfonate, perfluorooctanoic acid, perfluoro-n-hexane sulfonate, perfluoro-nonanoic acid, perfluoro-decanoic acid, 6:2-fluoropolymer sulfonate compound, 8:2-fluoropolymer sulfonate compound, perfluoro-heptanoic acid, and polyfluorinated carboxylic acid.

3. The sustainable system process for removing perfluorinated or polyfluoroalkyl substances as described in claim 1, characterized in that, The foam separator in S1 includes a foam separation tower, an active agent dosing facility, an aeration facility, and a foam phase scraper separator.

4. The sustainable system process for removing perfluorinated or polyfluoroalkyl substances as described in claim 1, characterized in that, The nanofiltration membrane system in S2 includes a GE Osmonics antifouling tubular membrane module, a multi-media filter, an activated carbon filter, a pH adjustment system, fluid control equipment, inlet and outlet water conductivity meters, a backwashing system, and a PLC control system.

5. The sustainable system process for removing perfluorinated or polyfluoroalkyl substances as described in claim 1, characterized in that, The S2 nanofiltration membrane system is operated with the following parameters: influent pH value of 6-8, operating pressure of 10-20 bar, operating temperature of 15-35℃, product water recovery rate of 50-70%, and concentration factor of 5-10 times.

6. The sustainable system process for removing perfluorinated or polyfluoroalkyl substances as described in claim 1, characterized in that, The S2 consists of two parallel ion exchange resin columns and internally filled resin, an air backwashing aeration system, a regenerated liquid backwashing system, and a pipeline gate control system.

7. The sustainable system process for removing perfluorinated or polyfluoroalkyl substances as described in claim 1, characterized in that, The resin used in the ion exchange resin column of S2 is PFR-630N resin.

8. The sustainable system process for removing perfluorinated or polyfluoroalkyl substances as described in claim 1, characterized in that, The electrocatalytic unit 1 in S4 and the electrocatalytic unit 2 in S5 have the same structure, both including multiple sets of plate electrode groups, an inlet pump, an inlet pipe, an outlet pipe, electrodes, and a high-frequency power supply.

9. A sustainable system process for removing perfluorinated or polyfluoroalkyl substances as described in claim 8, characterized in that, The anode of the electrode is a multi-layer titanium plate, and the cathode is a multi-layer semiconductor plate. The electrode spacing is 10-15 cm, the voltage is 15-20 V, and the current density is 10-30 mA / cm². 2 .

10. A sustainable system process for removing perfluorinated or polyfluoroalkyl substances as described in claim 9, characterized in that, The cathode uses a single-crystal silicon wafer as a substrate, on which a layer of SiO2 is grown, and then a layer of aluminum, bismuth or Rh metal elements is vapor-deposited on the surface.

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