PFAS treatment scheme using separation and electrochemical exclusion

Abstract

To provide a system for treating a source of water contaminated with PFAS.SOLUTION: The system includes: a PFAS separation stage having an inlet fluidly connectable to the source of water contaminated with PFAS, a diluate outlet, and a concentrate outlet; and a PFAS elimination stage positioned downstream of the PFAS separation stage and having an inlet fluidly connected to an outlet of the PFAS separation stage. The elimination of the PFAS is performed onsite with respect to the source of water contaminated with PFAS, with the system maintaining an elimination rate of PFAS greater than about 99%. A method of treating water contaminated with PFAS is also provided.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] (Cross-reference of related applications) This application is a claim filed on June 7, 2019, for "PFAS Treatment Sch eme Using Ion Exchange and Electrochemic U.S. Provisional Patent Application No. 62 / 858, entitled “al Advanced Oxidation” Priority under Patent No. 401 is claimed under Section 119(e) of the U.S. Patent Act, and the entire disclosure is claimed. It is incorporated herein by reference in its entirety for all purposes. (Technical field)

[0002] The embodiments and models disclosed herein generally relate to the process of extracting perfluoroalkyl from water. This relates to the field of removal and elimination of substances (PFAS). [Background technology]

[0003] Concerns about the presence of various pollutants in urban wastewater, surface water, drinking water, and groundwater. Concerns are rising. For example, in addition to general concerns about total organic carbon (TOC), PFA In addition to S and PFAS precursors, perchlorate ions in water are also a cause for concern.

[0004] PFAS is composed of fluorine, carbon, and heteroatoms such as oxygen, nitrogen, and sulfur. These are mechanical compounds. The hydrophobicity of fluorocarbons and the extreme electronegativity of fluorine are the reasons for their properties. And it imparts special properties to similar compounds. Initially, many of these compounds were used in integrated circuits. They were used as gases in manufacturing. The ozone-depleting properties of these molecules were due to their use This has led to methods to limit use and prevent release into the atmosphere. However, other substances such as fluorinated surfactants... PFAS is becoming increasingly popular. PFAS is used in carpets, upholstery, and stain-resistant materials. It is commonly used as a surface treatment / coating for consumer goods such as apparel, cookware, paper, and packaging. It is used and can also be found in chemicals used in chemical plating, electrolytes, lubricants, etc. This can ultimately lead to water supply. Furthermore, PFAS is a water-soluble film-forming foam (AFF). It is used as a main component of F). AFFF is used in military and urban fire training grounds around the world. This product is ideal for firefighting operations in oil and gas refineries. AFFF is also suitable for firefighting in oil and gas refineries. It is widely used in both training and firefighting drills. AFFF covers spilled oil / fuel. It works by cooling the surface and preventing re-ignition. PFAS during AFFF Many of these bases and refineries, including more than 100 U.S. Air Force bases, have contaminated groundwater. It is.

[0005] These compounds, despite being used in relatively small amounts, are easily released into the environment, and In the environment, due to its extreme hydrophobicity and similarly negligible rate of biodegradation, the environment This leads to persistence and bioaccumulation. Even low levels of bioaccumulation can occur in contaminated humans and other organisms. It could have serious health consequences for animals, and young people are particularly susceptible to the effects. The environmental impacts of these compounds on plants and microorganisms are still largely unknown. No, it hasn't. Nevertheless, serious efforts to limit the release of PFAS into the environment are now underway. It is. [Overview of the Initiative]

[0006] According to one aspect, an on-site system for treating a source of water contaminated with PFAS is provided. The on-site system includes a PFAS separation stage having an inlet, a diluent outlet, and a concentrate outlet that are fluidly connectable to a source of water contaminated with PFAS, and a PFAS removal stage located downstream of the PFAS separation stage and having an inlet fluidly connected to the outlet of the PFAS separation stage. The removal of PFAS by the system can be performed on-site with respect to the source of water contaminated with PFAS. 。

[0007] In some embodiments, the system maintains the concentration of PFAS in the diluent of the PFAS separation stage below a predetermined threshold. For example, the predetermined threshold can be less than 70 parts per trillion (70 ppt), which is the total lifetime exposure maximum standard of the United States Environmental Protection Agency. In certain embodiments, the predetermined threshold is less than 12 ppt. concentration below a predetermined threshold. For example, the predetermined threshold can be less than 70 parts per trillion (70 ppt), which is the total lifetime exposure maximum standard of the United States Environmental Protection Agency. In certain embodiments, the predetermined threshold is less than 12 ppt.

[0008] In further embodiments, the system includes a hardness removal stage. In some embodiments, the system includes a control system configured to regulate the feed directed between the PFAS separation stage and the PFAS removal stage. In some embodiments, the system includes a PFAS sensor located downstream of the diluent outlet of the PFAS separation stage. In some embodiments, the system includes a hardness removal stage. In some embodiments, the system includes a control system configured to regulate the feed directed between the PFAS separation stage and the PFAS removal stage. In some embodiments, the system includes a PFAS sensor located downstream of the diluent outlet of the PFAS separation stage. In some embodiments, the system includes a hardness removal stage. In some embodiments, the system includes a control system configured to regulate the feed directed between the PFAS separation stage and the PFAS removal stage. In some embodiments, the system includes a PFAS sensor located downstream of the diluent outlet of the PFAS separation stage. In some embodiments, the system includes a hardness removal stage. In some embodiments, the system includes a control system configured to regulate the feed directed between the PFAS separation stage and the PFAS removal stage. In some embodiments, the system includes a PFAS sensor located downstream of the diluent outlet of the PFAS separation stage.

[0009] In certain embodiments, the PFAS separation stage includes one or more ion exchange modules. The ion exchange modules can be regenerated to remove the bound PFAS and produce a PFAS concentrate. In some embodiments, the regeneration includes contacting the ion exchange modules with a regeneration solution containing methanol, water, and NaOH. In certain embodiments, the PFAS separation stage includes one or more ion exchange modules. The ion exchange modules can be regenerated to remove the bound PFAS and produce a PFAS concentrate. In some embodiments, the regeneration includes contacting the ion exchange modules with a regeneration solution containing methanol, water, and NaOH. In certain embodiments, the PFAS separation stage includes one or more ion exchange modules. The ion exchange modules can be regenerated to remove the bound PFAS and produce a PFAS concentrate. In some embodiments, the regeneration includes contacting the ion exchange modules with a regeneration solution containing methanol, water, and NaOH. In certain embodiments, the PFAS separation stage includes one or more ion exchange modules. The ion exchange modules can be regenerated to remove the bound PFAS and produce a PFAS concentrate. In some embodiments, the regeneration includes contacting the ion exchange modules with a regeneration solution containing methanol, water, and NaOH.

[0010] In some embodiments, the PFAS separation stage includes one or more nanofiltration modules. Prepare. The concentrate containing PFAS from one or more nanofiltration modules is prepared by one or more nano The filter passes through one or more nanofiltration diafiltration modules downstream of the filtration module. This can increase the PFAS concentration. In some cases, one or more The nanofiltration diafiltration module removes NaCl and / or KCl. The goal is to achieve this.

[0011] In some embodiments, the PFAS separation stage is used for adsorption onto an electrochemically active substrate. It is accompanied by. Electrochemically active substrates may include granular activated carbon (GAC). GAC is electrically... It can be incorporated into electrodes within a chemical cell. In some embodiments, the electrodes within the electrochemical cell are Platinum, dimensionally stable anode (DSA) coated with mixed metal oxide (MMO) The material comprises graphite or lead / lead oxide. In further embodiments, the electrochemical cell is , containing sulfate electrolytes. In certain embodiments, the electrochemical cell is an ion exchange membrane separator. - Equipped with. PFAS adsorbed onto an electrochemically active substrate is the electrical activity of the electrochemical cell. It can be detached through sexualization.

[0012] In some embodiments, the PFAS separation stage includes foam fractionation.

[0013] In some embodiments, the PFAS exclusion stage is an electrochemical PFAS exclusion stage. It includes, for example, an electrochemical PFAS exclusion stage, an electrochemical cell, and other electrically facilitating processes. It may be equipped with an oxidation system.

[0014] In some embodiments, the electrochemical cell is a boron-doped diamond (BDD) electrode. It is accompanied by.

[0015] In certain embodiments, the electrochemical cell is a magnesium phase titanium oxide electrode, particularly Ti n O2 n-1 (n=4~10) The system involves electrodes. An exemplary electrode is Ti4O7.

[0016] In some embodiments, the electrodes of the electrochemical cell are made of stainless steel, nickel alloy, titanium, etc. It is made of a material called or DSA material. In some embodiments, the electrochemical cell is made of hydroxide It contains an electrolyte comprising at least one of sulfates, nitrates, and perchlorates.

[0017] In some embodiments, the PFAS exclusion stage is used in the accelerated oxidation process (AOP) reaction. The container is equipped with a device. For example, AOP may involve UV persulfate treatment or plasma treatment.

[0018] According to one embodiment, a method for treating water contaminated with PFAS is provided. This method is Contaminated water from a water source contaminated with PFAS at a first concentration is separated into a PFAS separation stage. This may include introducing it at the inlet. This method involves treating the contaminated water in a PFAS separation stage. , generated water that is virtually free of PFAS and a second PFAS concentration higher than the first PFAS concentration This method may further include producing a PFAS concentrate having a degree. Introducing the concentrated FAS solution into the entrance of the PFAS elimination stage, and the PFAS elimination stage This method may include activating and removing PFAS from the PFAS concentrate. It can have a PFAS elimination rate of over 99%.

[0019] In some embodiments, PFAS elimination is performed on-site with respect to the source of contaminated water. It breaks.

[0020] In a further embodiment, the method processes the PFAS concentrate from the PFAS separation stage. This may include processing to produce a concentrate having a third concentration of PFAS. The S concentration may be higher than the second PFAS concentration. The concentrated solution can be introduced at the entrance of the PFAS elimination stage.

[0021] In some embodiments, this method involves the pressure in the source water and / or the generated water. This may further include monitoring temperature, pH, concentration, flow rate, or TOC levels.

[0022] In certain embodiments, the PFAS separation stage comprises one or more ion exchange modules. In some embodiments, the PFAS separation stage includes one or more nanofiltration modules. It is equipped with a PFAS separation stage. In some embodiments, the PFAS separation stage is equipped with an electrochemically active group. Adsorption to a plate is involved. In some embodiments, the PFAS separation stage involves foam fractionation.

[0023] In some embodiments, the PFAS exclusion stage is an electrochemical PFAS exclusion stage. It includes, for example, an electrochemical PFAS exclusion stage, an electrochemical cell, and other electrically facilitating processes. It may be equipped with an oxidation system.

[0024] In some embodiments, the electrochemical cell is accompanied by a BDD electrode.

[0025] In some embodiments, the electrochemical cell is accompanied by a titanium oxide electrode in the Magneli phase.

[0026] In some embodiments, the electrochemical cell is used to process hydroxides, sulfates, nitrates, and perchlorates. It contains an electrolyte that includes at least one of the salts.

[0027] In some embodiments, the PFAS exclusion stage includes an AOP reactor. For example, AOP may involve UV persulfate treatment or plasma treatment.

[0028] In another embodiment, a method for refurbishing a water treatment system is provided. This method is PFA Prepare the S exclusion stage, and connect the PFAS exclusion stage to the fluid downstream of the PFAS separation stage. This may include continuing.

[0029] In some embodiments, the PFAS exclusion stage is an electrochemical PFAS exclusion stage. It includes, for example, an electrochemical PFAS exclusion stage, an electrochemical cell, and other electrically facilitating processes. It may be equipped with an oxidation system.

[0030] In some embodiments, the electrochemical cell is accompanied by a BDD electrode.

[0031] In certain embodiments, the electrochemical cell is accompanied by a magnesium phase titanium oxide electrode.

[0032] In some embodiments, the PFAS exclusion stage includes an AOP reactor. For example, AOP may involve UV persulfate treatment or plasma treatment.

[0033] The attached drawings are not intended to be drawn to scale. Each identical or nearly identical component shown in the various diagrams is represented by a similar number. For the sake of clarity, not all components are labeled in every drawing. do not have. [Brief explanation of the drawing]

[0034] [Figure 1]This is a flowchart of a PFAS treatment system where water recovered from PFAS removal is collected as treated water. The inserted table provides modeled concentrations of various components in the water flow at specific locations within the system. [Figure 2] This is a flowchart of a PFAS treatment system where water recovered from PFAS removal is used as makeup water for supplying the PFAS separation stage. The inserted table provides modeled concentrations of various components of the water flow at specific locations within the system. [Figure 3] This is a flowchart of a PFAS treatment system configured to remove high concentrations of partially oxidized PFAS. [Figure 4] This is a flowchart of a PFAS treatment system in which nanofiltration is used as the PFAS separation stage. [Figure 5] This is a flowchart of a PFAS treatment system in which nanofiltration is used as the PFAS separation stage. The inserted table provides modeled concentrations of various components of the water flow at specific locations within the system. [Figure 6] This is a flowchart illustrating a method for separating PFAS from a water source using adsorption to a GAC ​​electrode and desorption of PFAS from the GAC electrode within an electrochemical cell. [Figure 7] This figure shows a series of reactions that occur on the electrode surface during the electrochemical exclusion of PFAS. [Figure 8] This scatter plot shows the length of time required to reduce both the total PFAS concentration and the concentration of each PFOS species without concentrating PFAS separated from the water source. [Modes for carrying out the invention]

[0035] According to one or more embodiments, the systems and methods disclosed herein are PFAS This relates to the isolation, concentration, and elimination of PFAS from contaminated water sources. The compounds are very stable and resistant to degradation in the environment. They are also soluble. As a result, they become negatively charged and can have high water solubility. They are being developed as waterproofing agents and It was widely used as a protective coating. Some PFAS compounds are now mostly stepwise Although it has been abolished, the increase in levels is still widespread. For example, PFAS The contaminated water was found in industrial areas where it was manufactured or used, as well as in areas where fire drills were conducted. PFAS can be found near airfields or military bases. PFAS are transmitted by the movement of water or air. It can be found even in remote areas. Many urban water systems are undergoing active testing and treatment. The present invention relates to the treatment of negatively charged and / or fluorinated compounds. It is not limited to Ipu.

[0036] In some specific, non-limiting embodiments, perfluorooctanoic acid (PFOA) and or common PFAS such as perfluorooctanesulfonic acid (PFOS) in water It can be removed. In May 2016, the U.S. Environmental Protection Agency (EPA) approved PFOS and PFOA. The revised guidelines state that the total lifetime exposure is 70 parts per trillion (70 ppt). Federal, state, and / or private organizations may also issue relevant regulations. For example, New Hampshire has a rating of 12 ppt for PFOA and 15 ppt for PFOS. Fluorohexanesulfonic acid (PFHxS) 18 ppt, perfluorononanoic acid For PFNA, the maximum groundwater contaminant level (MCL) of 11 ppt is used. In some cases, the systems described herein regulate the concentration of PFAS in treated water. It can be maintained below the level.

[0037] According to one or more embodiments, enriched PFA for enhancing the conversion or degradation of PFAS To provide an S-flow, PFAS can be separated from the process flow. By concentrating the PFAS flow... , necessary to destroy PFAS by known methods such as electrochemical oxidation or photochemical oxidation Energy consumption will be reduced.

[0038] The system of the present invention has an inlet that can be fluidly connected to a water source contaminated with PFAS, and a diluent. A PFAS separation stage having an outlet and a concentrated liquid outlet, and located downstream of the PFAS separation stage A PFAS exclusion stage having an inlet fluid-connected to the outlet of the PFAS separation stage, This includes the following. During processing, the water source contaminated with PFAS is led to the inlet of the PFAS separation stage. It is added. PFAS is separated from water, and the PFAS-enriched concentrate is used for drinking water and irrigation water. The system of the present invention generates a diluent that can be discharged for its original purpose. The concentration of PFAS in the diluent of the S separation stage should be determined according to standards of the United States, state, or private organizations. It can be maintained below a predetermined threshold. The system of the present invention divides PFAS from the source of contaminated water. It has an advantage in that the removal of separated and isolated PFAS is carried out on-site with respect to the water source. Typically, separated PFAS are concentrated and then transported to another facility for elimination. However, this is dangerous and costly. Furthermore, eliminating PFAS would allow for the recovery of F - Ions and HF are generated, and both are used in applications such as glass etching and metal cleaning. It is useful in industrial processes and electronics manufacturing.

[0039] (PFAS separation) PFAS, as a class of compounds, are very stable compounds containing carbon-fluorine bonds. Therefore, it is extremely difficult to process. The carbon-fluorine bond is the strongest known single bond in nature. It is a bond and is highly resistant to destruction. PFAS has varying degrees of success. PFAS can be removed from the source of contaminated water by several known mechanisms. Conventional activated carbon adsorption systems and methods for removing longer alkyl chain PFAS It has been shown to be effective for, but when processing shorter alkyl chain compounds, It has a short floor life. Some conventional anion exchange resins have longer alkyl chain PFA It has been shown to be effective for S, but when processing shorter alkyl chain compounds, It has a short floor lifespan.

[0040] (Ion exchange) In some embodiments, the separation of PFAS from the source of contaminated water is performed by cation exchange. Alternatively, this can be achieved using ion exchange processes such as anion exchange. Conventional anions The exchange processing system and method typically involves positively charged anion exchange resin beads being PFAS It is placed inside a reed container that receives a flow of water contaminated with anionic pollutants such as It utilizes an on-exchange resin. Negatively charged contaminants are removed by positively charged resin beads. Wrapped and clean water is also used to remove anion exchange resin beads from the lead anion exchange container. It flows into the lug container containing it. The sample tap is an anion exchange bead in the lead exchange container. It is often used to determine when the majority of the resin is saturated with contaminants. As the replacement beads approach saturation, levels of contaminants are detected in the effluent tap. When this occurs, the lead container goes offline at that point, and the contaminated water is released at that point. The material continues to flow into the lead container, which is the lug container. The lead lug container configuration ensures a consistently high level of processing. This will be maintained.

[0041] As described above, PFAS can be removed from water using several conventional anion exchange resins. It is possible. There are many known methods for regenerating anion exchange beads in anion exchange containers. Yes, it exists. Some known methods rely on washing away the resin with salt water or a caustic solution. Other known methods enhance the removal of PFAS trapped in anion exchange beads. Therefore, it may involve the addition of a solvent such as methanol or ethanol. Effective resin regeneration is A solvent blended with a solution containing sodium chloride, sodium hydroxide, or another salt. This has been demonstrated by passing (methanol, ethanol, etc.) through the resin. However, Therefore, large quantities of toxic substances must be disposed of in such a manner at considerable expense. A regenerated solution can be produced. In addition, to concentrate PFAS and reduce the volume of waste Furthermore, the waste recycling solution needs to be treated further. The recycling of resins results in a significant volume of toxic waste. This is an important step because it generates material.

[0042] According to one or more embodiments, the PFAS separation stage removes PFAS from water. Therefore, it includes an ion exchange container having a selective ion exchange resin such as an anion exchange resin. In water sources contaminated with FAS, PFAS binds to selective anion exchange resins, and the water is affected. It is introduced into the inlet of a PFAS separation stage with ion exchange so that it can be removed. The solution is used regularly to remove PFAS from the anion exchange resin, thereby The anion exchange resin is regenerated and used from the removed PFAS and regeneration solution. A regenerated solution is produced. The PFAS concentration of the regenerated solution is determined by removing the liquid volume from the regenerated solution. This can be increased by enabling partial reuse of the regenerated solution. PFAS enrichment concentration The residual solution is further treated for PFAS elimination using a PFAS elimination stage. It is possible.

[0043] A regeneration solution containing a salt solution and alcohol is effective in regenerating anion exchange resin. This has been demonstrated. The anionic systems used in these regenerative chemistrys include, for example, C, among others. l - , OH - SO4 2- and NO3 - These can be selected from among others. All of these ions While effective in regenerating ion exchange resins, there are differences in removal efficiency. To maintain balance, there is also a chain effect of anion selection in the PFAS elimination stage. For example, chloride ion solutions are frequently used for ion exchange regeneration, but within electrochemical cells... As a result, chloride ions are preferentially driven to hypochlorite or chlorate, and energy consumption and The inefficiency of PFAS oxidation increases significantly, which casts a shadow on the electrochemical PFAS elimination system. It gives a sound. Furthermore, some chlorides are oxidized to perchlorates. This is environmentally harmful. It is a persistent anion and requires further processing. It is useful for the regeneration of anion exchange resins. A sulfate ion solution of an effective concentration has the effect of suppressing the oxidation of PFAS. Nitrate ion solution Both hydroxide ion solutions are suitable, however, comparing MCL values The nitrate has a primary MCL of 10 ppm, and the hydroxide has a potential pH in the overall solution. This will cause problems. Sulfate ions have a secondary MCL of 250 ppm, therefore hydroxide The solution can be neutralized with sulfuric acid after oxidation. In order to effectively regenerate PFAS, A water-miscible solvent is required in the solution. As described herein, alcohol is... Methanol is an example of an alcohol that is a useful solvent for the purpose of [the stated purpose].

[0044] The chloride and sulfate concentrations in the regeneration solution are determined by using methanol-free NaOH to regenerate the solution. It can be substantially reduced by stripping the resin first. By stripping, at least 95% or more of other anions can be removed. It may be possible. The used NaOH portion can be neutralized and replenished to the source of the contaminated water. It can be reused as water. Subsequent stripping with methanol and NaOH is Removes PFAS without other anions. In some cases, the initial regeneration is with a regeneration solution. Because a significant portion of the anions were stripped away, the second regeneration was of lower NaOH. This can be done using concentration. Prepare PFAS concentrates without the burden of associated anions. This makes the subsequent processing of the PFAS concentrate more efficient and effective.

[0045] Regardless of the choice of anionic system, remove the alcohol before oxidation and the PFAS in the concentrate. Further concentration is necessary. Removal of methanol from PFAS concentrate is usually done by distillation, etc. This can be achieved thermally. According to some embodiments, to concentrate PFAS in solution Methanol removal can be performed using solvent-resistant nanofiltration, diafiltration, or pervaporation. This can be achieved using paration. A portion of the regeneration solution is recovered and PFAS is dissolved in it. Other techniques for increasing the concentration of are known in the art.

[0046] PFAS is removed from water using ion exchange, and PFAS is desorbed from the ion exchange resin. To use a regeneration solution and to increase the concentration of PFAS in the residual regeneration solution Figures 1 to 3 show a water treatment system that removes a portion of the regeneration solution.

[0047] (filtration) In some embodiments, the separation of PFAS from the source of contaminated water is performed by membrane filtration. This can be achieved using any physical separation process. In such cases, the membrane allows water to pass through. Sufficient to enable, but with pores of a diameter that can hold and collect PFAS According to one or more embodiments, the PFAS separation stage is one or more solvent-resistant nanofilters. Includes a transient stage. The number of nanofiltration stages used in the PFAS separation stage of the present invention The type of nanofiltration membrane will depend on the matrix of the contaminated water source. The nanofiltration membrane then filters high concentrations of total suspended solids (TSS), free chlorine, and specific types of solids in the solution. It is susceptible to damage from heavy metals (such as Al, Mn, Fe, and Zn). Therefore, contamination with PFAS is a risk. If the source of contaminated water has high TSS, free chlorine and / or heavy metals, PFA Before S separation, use one or more pretreatments to remove excess TSS, chlorine, and / or heavy metals. It should be removed.

[0048] The permeate from one or more stages of nanofiltration is substantially free of PFAS. The concentrate of Tage has a PFAS enrichment concentration. As described herein, in the concentrate PFAS reduces energy consumption and enhances the effectiveness of subsequent PFAS elimination stages. Therefore, it may have a further enriched concentration. In some embodiments, nanofiltration PFAS The concentrated liquid from the separation stage is introduced into the inlet of another nanofiltration diafiltration stage. If possible, remove excess salts such as NaCl or KCl from the concentrate, and further, this step The concentrated solution obtained is then concentrated with PFAS. The water is composed of water from an external source with a low TSS content. The diluted solution obtained from this step can be used as constituent water in a contaminated water source.

[0049] According to a particular embodiment of the nanofiltration-based PFAS separation stage, the nanofiltration is incorporated The system of the present invention may include a stage for removing hardness by chemical precipitation or the like. Insoluble alkaline earth minerals such as calcium sulfate or magnesium sulfate, phosphates, and carbonates. Potential scaling or filamentous flammability of films or other downstream process equipment introduced by metal salts If fowling is a concern, a hardening removal stage may need to be included as needed. The hardness removal stage removes PFAS enriched concentration from one or more nanofiltration PFAS separation stages. It can be configured to accept condensed liquid.

[0050] The water is treated using one or more nanofiltration stages to remove PFAS from the water. Hardness is removed from the PFAS-enriched concentrate from the nanofiltration stage, and the PFAS in the residual solution is removed. To increase the concentration, an additional stage of nanofiltration diafiltration is used. The stem is shown in Figures 4 and 5.

[0051] (adsorption) In some embodiments, the separation of PFAS from the source of contaminated water is performed by an adsorption process. This can be achieved using, where PFAS is physically trapped within the pores of the porous material. (i.e., physical adsorption) or having a favorable chemical interaction with the function on the filtration medium. That is, chemical adsorption). According to one or more embodiments, the PFAS separation stage is electrified This may include adsorption onto a chemically active substrate. Electrochemistry that can be used to adsorb PFAS. An example of a substrate that is actively activated is granular activated carbon (GAC). Adsorption to GAC is also observed with other PFAS. Compared to separation methods, it is a low-cost solution for removing PFAS from water. This results in the mass production of harmful regeneration solutions in ion exchange containers, as well as nanofiltration and backfiltration. Other issues include the low recovery rate and high energy consumption of membrane-based separation methods such as RO (reverse osmosis). This may potentially avoid known problems regarding the removal method. Similar to ion exchange, GAC absorbs This removes PFAS from the source of contaminated water. However, the PFAS removal stage... The adoption of GAC in the process is achieved by incinerating at temperatures exceeding 600°C. However, this would result in very high energy and cost.

[0052] In some embodiments, the GAC used for adsorption removal of PFAS is deprotonated. Modified to enhance its ability to remove negatively charged species such as PFAS from water. This is possible. For example, GAC preferentially interacts with negatively charged PFAS in solution. It can be coated with a positively charged surfactant. Positively charged surfactants include cetyltri Quaternary ammonium-based surfactants such as methylammonium chloride (CTAC) It is possible. All activated carbons useful for the present invention and modifications that can be made to said activated carbons are all Copyright 8,932,984 U.S., owned by Evoqua Water Technologies, Inc. U.S. Patent No. 9,914,110 and PCT / US2019 / 046 As described in 540, each of these is by reference in whole for all purposes. This specification is incorporated herein.

[0053] In this invention, the adsorption properties of GAC are used as a component of the electrode in an electrochemical cell. It is advantageous for this purpose. GAC electrodes are made of GAC, conductor (graphite or carbon black). (etc.) and a suitable binder (e.g., polytetrafluoroethylene (PTFE) or poly Contains vinylidene fluoride (PVDF). When GAC electrodes are used in electrochemical cells. Other electrodes are chemically and electrochemically stable electrodes, such as platinum, MMO coated electrodes. DSA material, graphite, Pb / PbO2, and other materials known in the art. In certain embodiments, a cation exchange membrane is embedded between both GAC electrodes. In this case, both the cathode and anode of the electrochemical cell can be GAC electrodes.

[0054] A typical process for reversibly adsorbing and desorbing PFAS from a contaminated water source using a GAC ​​electrode is shown in Figure 6, which can be broadly described as a three-step process. In step 1, a PFAS-contaminated water source is circulated around the GAC electrode, leaving the PFAS adsorbed on the electrode surface. Step 1 can be performed in batch mode if the PFAS contamination level of the water source is high. Alternatively, if the PFAS contamination level of the water source is low, step 1 can be performed in a single pass. In step 2, the prepared synthetic water is circulated through an electrochemical cell, the cathode of which is a GAC ​​electrode, and an ion exchange membrane may be embedded between the electrodes. Activating the electrochemical cell, such as by applying a voltage or reversing the flowing current, removes the PFAS adsorbed on the GAC cathode. Remove and reattach Synthetic water circulating within the electrochemical cell concentratedThis allows for reduction. The preferred operating mode of step 2 is batch mode, in which the concentrated PFAS aqueous solution is collected for further elimination treatment. To reduce energy consumption, a salt (such as Na2SO4) may be added to the synthetic water circulating within the electrochemical cell to increase the conductivity of the water. The amount of salt added to the synthetic water depends on the discharge regulation of the subsequent elimination step, as described herein. Step 3 is a potential balancing step to zero charge of the GAC electrode to prevent a decrease in PFAS removal efficiency due to bilayer adsorption of cations to the GAC electrode. This step ensures that the GAC electrode recovered after PFAS desorption is charge-neutral and free of adsorbed salts. The PFAS desorbed from the GAC electrode may be further concentrated using the methods described herein or introduced into a PFAS elimination stage.

[0055] (Foam fractionation) In some embodiments, the separation of PFAS from the source of contaminated water is performed using foam fractionation. This can be achieved by generating bubbles at the source of the contaminated water, which rise and remove hydrophobic molecules from the water. Fractionation is typically used in aquatic environments, such as aquariums, to remove dissolved proteins from water. During the bubble fractionation, bubbles rise through the container of contaminated water and are large with a high charge. It forms bubbles with a large surface area air-water interface. The charged groups of the PFAS molecule are absorbed into the bubbles. It adheres and forms a PFAS-enriched surface layer that can be removed later. The bubbles are compressed air or nitrogen. It can be formed using any suitable gas. In some embodiments, bubbles are formed. The bubbles are formed from oxidizing gases such as ozone. A useful bubble fractionation system for this invention. This is known in the field of technology.

[0056] (PFAS eliminated) Various techniques can be employed to process the concentrated flow to result in PFAS conversion or decomposition. The removal of PFAS from the concentrated stream using the PFAS removal method described herein generates H + and F - ions.

[0057] (Electrochemistry) According to one or more embodiments, the PFAS removal stage may include an electrochemical PFAS removal stage that includes an electrochemically enhanced oxidation system. The electrochemically enhanced oxidation system may include an electrochemical cell used to decompose PFAS in water. The electrochemical cell may generally include two electrodes, namely, a cathode and an anode. A reference electrode may also be used, for example, near the anode. According to one or more embodiments, the cathode may be composed of various materials. Environmental conditions, such

[0058] as, for example, the pH level, and specific process requirements, such as those related to wash or maintenance, may affect the selection of the cathode. In some non-limiting embodiments, the cathode may be made of stainless steel, nickel alloy, titanium, or DSA material. The DSA material may or may not be coated, and may be coated with a noble metal or metal oxide (such as Pt or IrO2) or otherwise.

[0059] According to one or more embodiments, the anode may be composed of a material characterized by a high oxygen evolution overvoltage. The overvoltage may generally relate to the potential difference (voltage) between the thermodynamically determined reduction potential of the half-reaction and the potential at which the redox event is experimentally observed. This term may be directly related to the voltage efficiency of the electrochemical cell.

[0060] ​​​​​According to one or more embodiments, the anode may exhibit preference for surface reactions in water. Water molecules adhere to the surface based on the various physical properties and / or chemical composition of the anode. It can be repelled, while nonpolar organic pollutants can be easily absorbed. This is because direct contact with the surface. It can promote oxidation reactions, which may be particularly beneficial, for example, in the treatment of PFAS.

[0061] According to one or more embodiments, the anode is a general formula Ti n O2 n-1 (n=4 or more 10 It may consist of the following magnesium phase titanium oxide. The magnesium phase titanium oxide anode may be other Compared to anode materials, it may possess superior performance in suppressing oxygen generation. This allows for the direct oxidation of PFAS on the surface. In addition, other electric devices with similar overpotential characteristics Compared to other materials, magnesium-phase titanium oxide is cheaper than boron-doped diamond (BDD). It is more robust than Ti / SnO2 and more environmentally friendly than Pb / PbO2. PFAS-free. Magnel phase electrodes and electrochemical cells equipped with such electrodes are subject to PCT / US2019 It is described in / 047922, and that disclosure is by reference in its entirety for all purposes. This is incorporated herein. According to one or more embodiments, the anode is composed of a BDD. It is possible.

[0062] According to one or more embodiments, a magnesium phase titanium oxide anode or a BDD anode is It can be used in electrochemical cells. The anode can be formed in various shapes, for example, planar or circular. This is possible. In at least some preferred embodiments, the anode has a high active surface area and fine Characterized by a mesh or foam structure that may relate to the pore structure and / or pore distribution. obtain.

[0063] The supporting electrolyte selected for electrochemical PFAS elimination removes PFAS from contaminated water. It can be selected to minimize energy consumption for the purpose of electricity. As shown in Table 1, The solution is Cl - SO4 2- NO3 - ClO4 - and either of the OH- ions This may include. The energy consumption data in Table 1 is based on the processing of PFAS, particularly PFOA. This indicates the range of efficiency achieved by using various electrolytes in the source water. It is listed in Table 1. Among the electrolytes, NO3 - and ClO4 - Both of these are for PFAS elimination While effective, its disposal has significant environmental impacts. Reducing PFOA is important as a supporting electrolyte. This is possible by using a dilute Cl- solution. However, in practice, The main reactions that occur at the electrode surface are chlorination and oxygen evolution. As a result, free chlorine, chlorate ions, and perchlorate ions are generated in the solution, which can lead to secondary contamination. This raises concerns. SO4 2- Electrolytes are effective in eliminating PFAS and have no impact on the environment. The sound is low. However, sulfates are low in concentration (less than 20 mM, preferably about 5 mM SO2). 4 2- It is only effective in this range. This concentration range is insufficient for ion exchange regeneration processes. This result also indicates that SO4 is strongly adsorbed on the electrode surface. 2- The electrolyte is the electricity of OH· This is consistent with literature suggesting that it does not promote oxidative production. PFAS excretion of NaOH electrolyte. The removal efficiency is inversely proportional to the NaOH concentration, but NaOH is a balanced electrolyte in general. This represents the choices that were made.

[0064] [Table 1]

[0065] During operation, the process flow containing elevated PFAS levels is processed by an electrochemical cell. It can be introduced into the electrochemical cell, as described herein, using magnesium phase titanium oxide. It may include an anode or a BDD anode. The anode material is porous with at least about 25% porosity. It may have properties. The anode material has an average pore size in the range of approximately 100 μm to approximately 2 mm. The electrochemical cell may contain an electrolyte as described herein, and the voltage may be the desired voltage. To provide processing for the bell, it may be applied to the anode as described herein. Various pre-processing and / or post-processing unit operations can also be integrated. The generated flow is additional It may be directed to further unit operations for processing, or sent to the place of use or other It can be discharged by method. The polarity of the electrochemical cell is desired, for example, to facilitate maintenance. In that case, it may reverse periodically.

[0066] According to one or more embodiments, formulas 1 to 5 shown in Figure 7 represent BDD or Magneli phase oxidation. Titanium (Ti n O 2n-1 ) The basic mechanism of electrochemical PFAS removal using an anode It can represent a symmetry. The reaction can generally be characterized as a Kolbe-type oxidation. The reaction is ten By applying a positive voltage, carboxylic acid ions are formed on the electrode surface. It begins with direct oxidation to (Equation 1). Subsequently, the carboxylate radical is decarboxylated. This forms a perfluoroalkyl radical (Equation 2). Perfluoroalkyl radicals are electrically charged By coupling with hydroxyl free groups anodically generated at the polar surface, perfu It is converted to a ruo-alcohol (Equation 3), which is further defluorinated to perfluorofluorine It becomes a carbonyl compound (formula 4), and finally loses one carbon in the chain, resulting in a byproduct. It is then hydrolyzed to perfluorocarboxylic acid (Equation 5). Reactions 1 to 5 are generally PF All carbon from AS is ultimately converted into inorganic CO2, H + , and F - Stripped This can be repeated until...

[0067] (Photochemical treatment) According to one or more embodiments, the PFAS exclusion stage includes photochemical treatment of PFAS. It is possible. For example, ultraviolet (UV) treatment has been shown to be effective in decomposing PFAS. UV treatment generally utilizes UV activation of oxidized salts to eliminate various organic species. Any strong oxidizing agent can be used. In some non-limiting embodiments, persulfation Compounds may be used. In at least some embodiments, ammonium persulfate, sodium persulfate Thorium and / or potassium persulfate may be used. Other strong oxidizing agents, such as ozo, may also be used. Hydrogen peroxide may also be used. Oxidizing agents may be administered to the source of contaminated water.

[0068] According to one or more embodiments, a source of contaminated water to which an oxidizing agent has been administered is exposed to a UV light source. For example, the systems and methods disclosed herein involve one or more UV lamps This may include use, each emitting light at a desired wavelength within the UV range of the electromagnetic spectrum. According to some embodiments, the UV lamp has a wavelength range of approximately 180 nm to approximately 280 nm. It may have wavelengths in the range of about 185 nm to about 254 nm, and in some embodiments, wavelengths in the range of about 185 nm to about 254 nm. It may have. According to various embodiments, the combination of persulfate and ultraviolet light may have any It is more effective than using the ingredients individually.

[0069] UV treatment to remove organic compounds can be carried out by Evoqua Water Technology. VANOX (registered trademark) is sold by G's Corporation (Pittsburgh, Pennsylvania). )Including the AOP system, it is generally known. All Evoqua Water Technology U.S. Patent No. 8,591,730 and U.S. Patent No. 8,652,336, all owned by G's Corporation. Specification No., U.S. Patent No. 8,961,798, U.S. Patent Application Publication No. 2016 / 020 Specifications No. 77813, U.S. Patent Application Publication No. 2018 / 0273412 and PC Publication of several related patents and patent applications, including T / US2019 / 051861. The whole of the object is incorporated herein by reference for all purposes.

[0070] (plasma) According to one or more embodiments, the PFAS exclusion stage may include plasma treatment. Razma typically uses low-pressure or atmospheric-pressure high-voltage discharges in the presence of gas or a mixture of gases. These are generated as free electrons, partially ionized gas ions and fully ionized It generates gas ions. Free electrons and ion species in aquatic environments are found in contaminated water. This can cause decomposition of PFAS and other organic substances in the sample. The decomposition of FAS has been demonstrated and proven in the literature. According to reports, plasma is used to produce The resulting electrons may be mainly involved in the decomposition of PFAS, but also in the formation of plastics such as hydroxyl radicals. The secondary oxidation species generated by Zuma do not play a significant role in initiating the reaction.

[0071] According to one or more embodiments, one or more sensors are located upstream of the PFAS elimination stage. The level of the PFAS and / or downstream can be measured. The controller measures the PFAS level. It can receive input from sensors for intermittent or continuous monitoring. Monitoring is This can be done either on-site or remotely, in real time or with a delay. The detected PFAS levels are unacceptable, as indicated by regulatory authorities. It can be compared to threshold levels that may be considered to be pH, flow rate, voltage, temperature, and other concentrations. These additional characteristics are provided by various interconnections or interrelationship sensors throughout the system. It can be monitored. The controller responds to sensor inputs and sets various operating parameters. In other words, one or more control signals may be transmitted to adjust the applied voltage.

[0072] In another embodiment, a method for treating water contaminated with PFAS is provided. , contaminated water from a water source contaminated with PFAS at a first concentration is subjected to a PFAS separation stage. It is introduced at the inlet, and the contaminated water is treated in the PFAS separation stage to remove PFAS and It substantially contains a PFAS concentrate having a second PFAS concentration higher than the first PFAS concentration. This method may include producing water that does not undergo PFAS drainage. It is introduced at the entrance of the elimination stage and activates the PFAS elimination stage to activate the PFAS concentrate. This may further include removing the PFAS from the mixture. The PFAS removal rate is over 99%. It's possible. PFAS elimination will be carried out on-site at the source of the contaminated water.

[0073] In some embodiments, a method for treating water contaminated with PFAS involves PFAS isolation. The PFAS concentrate from the stage is processed to produce a concentrate with a third PFAS concentration. This may include the fact that the third PFAS concentration is higher than the second PFAS concentration. A method for treating the treated water involves a concentrated solution having a third concentration of PFAS, followed by a PFAS elimination stage. It may further include introducing it at the inlet. In some cases, source water and / or generated Process conditions such as water pressure, temperature, pH, concentration, flow rate, or TOC level are monitored during processing. It is viewed as such.

[0074] In another embodiment, a method for refurbishing a water treatment system as described herein is provided. This method provides a PFAS exclusion module downstream of the PFAS isolation stage. This may include fluidizing the PFAS exclusion module. PFAS isolation stage and / Alternatively, the PFAS exclusion stage is the PFAS isolation stage and / or as described herein. This could be a PFAS exclusion stage. For example, ion exchange, nanofiltration, or electrochemical activation. PFAS separation stage and / or electrochemical cell including adsorption to a suitable substrate, UV persulfate This is a PFAS removal stage that includes salt treatment or plasma treatment. [Examples]

[0075] The functions and advantages of these and other embodiments can be better understood from the following examples. These examples are intended to be illustrative and are not intended to limit the scope of the present invention. I can't. [Examples]

[0076] In this example, the direct electrochemical treatment of PFAS-contaminated water when it enters the water treatment system. Instead, we will explain the advantages of non-direct electrochemical treatment for PFAS elimination. The primary non-direct electrochemical reason for S exclusion is the energy required to facilitate the reaction. - The goal is to reduce consumption. Generally, electrochemistry at low concentrations (usually less than 100 ppm) The removal of organic species by oxidation follows an exponential relationship with energy input. Therefore, the reaction at the anode surface does not depend on the anode current, but rather on the reaction site. It is limited by the material transfer of the species. Therefore, EEO (energy consumption per order of magnitude) Typically, instead of measuring energy consumption per weight or mole of pollutants being removed, electricity is used. This is applied to explain the energy efficiency of chemical PFAS elimination systems.

[0077] As shown in Figure 8, the PFAS concentrations measured by LC / MS / MS are shown in Table 2 below. The time required to reduce the concentration of PFAS, particularly PFOS, by an order of magnitude is nonlinear. It exhibits form dependence. Referring specifically to the data in Figure 8, PFOS or total PF from water. To reduce AS by an order of magnitude, the processing time is 2.77 hours or 5.17 hours, respectively, clearly This shall apply to the defined BDD modules and process flows. Water to PFO The time required to reduce S or total PFAS depends on the module design, process flow conditions, and water Please note that this will vary depending on factors such as the matrix and the volume of effluent being treated.

[0078] [Table 2]

[0079] Processing to reduce all PFAS to 70 ppt, the guideline of the US EPA. Qm containing Cppb PFAS 3 Considering the volume of the source water, (logC+1.1 Approximately 55) PFAS removal is required.

[0080] Total PFAS removal by direct electrochemical PFAS elimination in the same process configuration as in Figure 8. The energy consumption for this purpose will be explained as follows:

number

[0081] However, by applying a process combined with electrochemical PFAS exclusion, ion exchange 10% of the original PFAS concentration via exchange or other techniques described herein. b Double PF When concentrating AS, the total energy consumption for PFAS removal is as follows:

number

[0082] Combining (1) and (2) above, we get the following:

number

[0083] Raw water containing 1000 ppt of PFAS and the desired 10 4 Consider the increase in PFAS concentration. And so it is as follows:

number

[0084] The above estimates the energy required in the process of concentrating PFAS using various technologies. It should be noted that ghee consumption (later defined as E (concentration)) is not taken into consideration. Yes, it is. However, the energy required to achieve this is not directly from the raw water. This is significantly lower than gaseous chemical oxidation when treating 1000 ppt of PFAS in source water. A very conservative estimate of E (decomposition of source PFAS) and E (decomposition of concentrated PFAS) The ratio is 10.

[0085] Therefore, by combining the concentration of PFAS and its elimination by BDD, 1000 ppt of P is obtained. The total energy consumption of the process that processes FAS is modified from (4) as follows: do.

number

[0086] In addition, while the capacity of BDDs is still limited by technology, it is restricted in industrial applications. Because processing over a period of time is usually required, direct oxidation treatment of raw water incurs considerable additional equipment costs. This is a concern. A comparison of module inputs is shown in (6).

number

[0087] Therefore, 1000 ppt of PFAS and 10 4 With the same raw water that has an improved concentration, The number of BDD modules required to directly treat the source water is limited to a certain period of time. This is 2241 times the number of modules. Commercial BDD modules may be expensive. Therefore, this cost is a major concern.

[0088] The second reason is the by-products resulting from the oxidation of chloride ions in the matrix of the contaminated water source. The goal is to control the product. In the case of direct electrochemical oxidation, the source water is necessarily BDD Chlorine, chlorates, and even perchlorates are generated on the node. Organochlorine disinfection by-products ( Rehalomethanes (such as THM) tend to be eliminated by the inactive anode, but salt Inorganic chlorine compounds, including chlorates and perchlorates, remain during processing in batch processes. It continues to accumulate. However, as described herein, PFAS enrichment procedure and BDD In a process that combines elimination, the source water matrix is ​​well controlled, and chloride The generation of by-products is significantly reduced.

[0089] Table 3 shows the results of 500 ppm NaCl and 500 ppm NaCl after treatment with a BDD anode. Regarding the concentrations of free chlorine, chlorate, and perchlorate in source water containing PFOA of pb The collected data is shown. Ion chromatography combined with a PROTOSILHPLC column. When PFOA decreased from 500 ppb to 20 ppb, as detected by Raffy The reaction was manually stopped and the chlorine species were analyzed. Here, 10 mM boric acid and 10% acetate were used. A tonitrile solution (adjusted to pH 8) was used as the mobile phase. Free chlorine was measured using iodine droplets. The procedure was carried out according to standard methods, while chlorates and perchlorates were used as the mobile phase, and carbonate and bicarbonate were used as the mobile phase. Using a METROSEP A Supp5 anion exchange column with a solution of salt It was measured by ion chromatography.

[0090] [Table 3] [Examples]

[0091] Figure 1 shows the removal of PFAS from the contaminated water source and the electrochemical discharge of the separated PFAS. A schematic diagram of a water treatment system including one or more anion exchange containers for removing pollutants is provided. The source of the staining water has a PFAS concentration of 0.1 to 100 ppb and one or more anion exchangers. It is directed towards one of the inlets of the container, and the PFAS in the water is adsorbed onto the anion exchange resin. This makes it possible. Treated water exiting one or more anion exchange containers contains PFAS at detectable concentrations. It does not have. After a predetermined time, the adsorbed PFAS is removed with 50-70% methanol, 30 Regeneration solution consisting of ~50% water and 0.5~1.0% NaOH in an anion exchange container It is removed from the anion exchange resin by rinsing it off. The PFAS-containing regeneration solution is an After exiting the ion exchange container, the PFAS concentration is 0.05 to 50 mg / L.

[0092] This facilitates electrochemical PFAS removal and allows methanol to be recovered from the regenerated solution for reuse. To do this, methanol is thermally removed from the PFAS-containing regeneration solution, and 5% of the total volume of the regeneration solution is removed. Remove 0-70%, leaving water and 1-2% NaOH. Dilute the collected methanol with an anvil. It is returned to the anion exchange regeneration solution as a replenishment stream during the ion exchange regeneration process. Contains PFAS. After removing methanol from the regeneration solution, the PFAS concentration of the regeneration solution concentrated at this point is... The concentration ranges from 0.1 to 100 mg / L. The PFAS-enriched regeneration solution is used for electrochemical PFAS removal. The PFAS is introduced into the removal stage and electrochemically oxidized until no PFAS remains. The treated water from the FAS removal neutralizes the remaining 1-2% NaOH, and the resulting neutralized water is The treated water is discharged without any detectable PFAS concentration. This is an example of a water treatment system. This is effective when the PFAS compounds in the source of the contaminated water have been almost completely oxidized. That is the case. [Examples]

[0093] Figure 2 shows the removal of PFAS from the contaminated water source and the electrochemical discharge of the separated PFAS. A schematic diagram of a water treatment system including one or more anion exchange containers for removing pollutants is provided. The source of the staining water has a PFAS concentration of 0.1 to 100 ppb and one or more anion exchangers. It is directed towards the container's inlet, allowing PFAS in the water to be adsorbed onto the anion exchange resin. The treated water exiting one or more anion exchange containers does not contain detectable concentrations of PFAS. After a specified time, add 50-70% methanol, 30-50% water and 0.5-1.0% By washing the anion exchange container with a regeneration solution consisting of NaOH, the adsorbed PF AS is removed from the anion exchange resin. The PFAS-containing regeneration solution contains one or more anion exchange The PFAS concentration after being removed from the container ranges from 0.05 to 50 mg / L.

[0094] This facilitates the removal of electrochemical PFAS and allows for the recovery of methanol from the regenerated solution for reuse. To achieve this, methanol is thermally removed from the PFAS-containing regeneration solution, and the entire regeneration solution Remove 50-70% of the product, leaving water and 1-2% NaOH. Collected methanol It is returned to the anion exchange regeneration solution as a supply stream during the anion exchange regeneration process. PFAS After removing methanol from the regeneration solution, the PFA of the regeneration solution concentrated at this point The S concentration is 0.1 to 100 mg / L. The PFAS enriched and regenerated solution is used to electrify the PFAS. It is introduced into an electrochemical PFAS exclusion stage that undergoes chemical oxidation, and in a regeneration solution containing enriched PFAS... Reduce the concentration of PFAS. In this example, electrochemical PFAS elimination enriches PF Not all PFAS are completely removed from the AS-containing regeneration solution. After electrochemical PFAS removal... The PFAS concentration is 0.005-5 mg / L. Due to incomplete electrochemical PFAS elimination... The resulting solution neutralizes the remaining 1-2% NaOH and is used in one of the PFAS separation stages. The ions are returned to one of the inlets of the anion exchange vessels, and the PFAS separation process continues. . [Examples]

[0095] Figure 3 shows the removal of PFAS from the contaminated water source and the electrochemical elimination of the separated PFAS. A schematic diagram of a water treatment system including one or more anion exchange containers for contamination is provided. The water source has a PFAS concentration of 0.1 to 100 ppb and one or more anion exchange bottles. It is directed towards one of the inlets of the container, and the PFAS in the water is adsorbed onto the anion exchange resin. To enable this, the treated water exiting the anion exchange container will not contain PFAS at detectable concentrations. After a specified time, add 50-70% methanol, 30-50% water and 0.5-1.0% By washing the anion exchange container with a regeneration solution consisting of NaOH, the adsorbed P Remove FAS from the anion exchange resin. The PFAS-containing regeneration solution is used in the anion exchange container. It appears and has a PFAS concentration of 0.05 to 50 mg / L.

[0096] This facilitates the removal of electrochemical PFAS and allows for the recovery of methanol from the regenerated solution for reuse. To do this, methanol is thermally removed from the PFAS-containing regeneration solution, and the total volume of the regeneration solution is Remove 50-70%, leaving water and 1-2% NaOH. The collected methanol is then used as follows: It is returned to the anion exchange regeneration solution as a replenishment stream during the anion exchange regeneration process. Contains PFAS. After removing methanol from the regeneration solution, the PFAS concentration of the regeneration solution concentrated at this point is... The concentration ranges from 0.1 to 100 mg / L. The PFAS-enriched regenerated solution is then subjected to electrochemical PFAS exclusion. The PFAS is introduced into the stage, where it is electrochemically oxidized, and the enriched PFAS-containing regenerated solution is then used. Reduce the concentration of PFAS. In this example, electrochemical exclusion of PFAS is performed. It was found that it was not oxidized almost completely. This is because the first pass of electrochemical exclusion Furthermore, it is shown that short-chain PFAS remain in the solution. This solution is then used in nanofiltration stages, etc. The remaining short-chain PFAS were concentrated using a membrane concentrator, and the remaining short-chain PFAS-enriched concentrate solution was prepared. This can generate the enriched solution, which is then returned to the electrochemical PFAS exclusion stage, thus leaving The complete oxidation of short-chain PFAS is promoted. Alternatively, the electrochemical exclusion of PFAS is promoted. If completed, the solution obtained from electrochemical PFAS exclusion will contain the remaining 1-2% NaO Neutralize H and enter one of the inlets of one or more anion exchange containers in the PFAS separation stage. It is returned to the source and the PFAS isolation process continues. [Examples]

[0097] Figure 4 provides a schematic diagram of a water treatment system including a nanofiltration PFAS separation stage. The nanofiltration PFAS separation stage may include one or more nanofiltration units, the number and type of which will depend on the water matrix of the PFAS-contaminated water source. The PFAS-contaminated water is directed to the inlet of one or more nanofiltration units. The permeate from one or more nanofiltration units is discharged as treated water that is substantially free of PFAS. The concentrate from one or more nanofiltration units is PFAS-rich. If there is concern that the concentrate has an ion enrichment concentration that could contaminate additional membranes in the water treatment system or cause scale formation in downstream process equipment, this PFAS-enriched concentrate is directed to the inlet of a hardness removal unit as needed. The PFAS-enriched concentrate is directed to the inlet of a nanofiltration diafiltration stage, either after passing through the hardness removal stage or after arriving directly from the concentrate outlet of the nanofiltration PFAS separation stage, to further concentrate PFAS from the original enriched PFAS concentrate and remove chloride salts from the permeate. The nanofiltration diafiltration concentration step involves using low TSS feedwater, such as diluents from RO or electrodialysis (ED) units, as replenishment water to wash away salts, and the resulting concentrate is PFA. S It is necessary to enrich the solution with PFAS. Furthermore, the PFAS-enriched concentrate is introduced into an electrochemical PFAS removal stage and electrochemically oxidized until no PFAS residue remains. The treated water from the electrochemical PFAS removal stage is returned to the first PFAS separation stage and combined with the treated water from the first PFAS separation stage to be discharged as treated water. [Examples]

[0098] Figure 5 shows the removal of PFAS from the contaminated water source and the electrochemical elimination of the separated PFAS. A schematic diagram of a water treatment system including one or more nanofiltration units for pollution is provided. The water source contains PFAS concentrations of 0.1–100 ppb and Na at 100–300 ppm. It has a Cl concentration. This supply prevents clogging of the membrane of one or more nanofiltration units and faulin Directed towards the inlet of the TSS removal stage configured to reduce G. TSS removal stage Direct the diluent from the to one of the one or more nanofiltration units to trap PFAS in water with a membrane and be able to collect it as a concentrate from one or more nanofiltration units The treated water exiting the one or more nanofiltration units has a PFAS concentration lower than 70 ppt, the current lifetime exposure limit of the US Environmental Protection Agency The concentrate from the one or more nanofiltration units has a PFAS concentration of 0.01 - 10 ppm, a Ca / Mg ion concentration on the order of more than 100 ppm, and a NaCl concentration of more than 1000 ppm To facilitate electrochemical PFAS removal, direct the concentrate from the one or more nanofiltration units towards the inlet of the hardness removal stage and reduce the concentration of Ca / Mg ions from the concentrate by chemical precipitation [[ID=1,3]]The resulting PFAS - enriched concentrate has a Ca / Mg concentration of less than 10 ppm at this point and is directed from the outlet of the hardness removal stage to a storage tank where it is used as feed water for the nanofiltration diafiltration stage to further concentrate the PFAS from the original enriched PFAS concentrate and remove chloride salts from the permeate. To dilute the salt concentration prior to nanofiltration diafiltration add water generated from a source of water with a low TSS concentration, such as from an RO or ED unit, to the storage tank holding the PFAS - enriched concentrate Add the diluent resulting from the nanofiltration diafiltration stage to the discharge from the PF AS separation stage as an effluent. After reducing the chloride salt concentration to less than about 100 ppm and increasing the PFAS concentration to 1 - 1000 ppm, further subject the PFAS - enriched concentrate to an electric ​​​​​​​​The chemical PFAS elimination stage is introduced, and PFAS residue is removed until it is less than 10 ppb. It is electrochemically oxidized. The treated water from electrochemical PFAS removal is subjected to the first PFAS separation. Return to the stage and mix with the treated water from the first PFAS separation stage. It is discharged as follows, and here the discharged water has a PFAS concentration of less than 70 ppt and 100-30 It has a chloride salt content of 0 ppm. [Examples]

[0100] GAC electrode (80% by weight GAC, 10% by weight graphite as conductor, binder as Using electrode material totaling 1.7g containing 10% by weight of high molecular weight polyethylene (PE) Then, 1 ppm of PFOA in 1 liter of water was adsorbed. 10 mM boric acid was used as the mobile phase. PROTOSIL When measured by ion chromatography combined with an HPLC column, the first 65% of 1 ppm PFOA was adsorbed onto GAC. Next, a platinum-coated titanium electrode was used as the anode. When a 20mA DC current is applied to the electrochemical cell using this method, the GAC electrode is 25mL The solution was regenerated with a Na2SO4 salt deionization (DI) solution. After 1 hour of electrochemical separation, the concentrated solution was obtained. 0.68 ppm of PFOA was detected in the sample. This corresponds to a recovery rate of 2.6%.

[0101] The expressions and terms used in this specification are for illustrative purposes only and are not limited to those used in this specification. It should not be considered a thing. The term "plural" as used herein means two Refers to the above items or components. "Includes", "contains", "performs", "possesses", The terms "contains" and "accompany" are used in the specification or claims, etc. It is an open-ended term, meaning "includes, but not limited to." Therefore, the use of such terms is inappropriate for the items and their equivalents listed thereafter. , similarly meaning to include additional items. Transitional phrases "consisting of" and "effectively ~ Only the phrases "consisting of" are restrictive or semi-restrictive transitional phrases with respect to the claims. Ordinal numbers such as "1st", "2nd", "3rd", etc., used to modify the claim elements in the claim. The use of the term itself does not imply any priority or order of any claim element over others. This does not mean the chronological order in which the actions of rank, order, or method are performed, but rather the claim To distinguish between claim elements, one claim element having a certain name may be distinguished from another claim element having the same name. Used solely as a label to distinguish it from primes (when ordinal terminology is used). .

[0102] Having thus described several aspects of at least one embodiment, various Those skilled in the art should understand that changes, modifications, and improvements can be easily made in any embodiment. Any feature described may be included in or be included in any other feature of any other embodiment. This may replace [the original text]. Such changes, modifications, and improvements are part of this disclosure. This is intended and is intended to be within the scope of the present invention. Therefore, the above description and The drawings are merely examples.

[0103] Those skilled in the art will see that the parameters and configurations described herein are illustrative and may vary in actual parameters. The data and / or configuration depend on the specific application in which the methods and materials of this disclosure are used. Please understand this. Those skilled in the art will also find equivalents to certain embodiments of the present invention. It should be possible to recognize or confirm this using only experiments.

Claims

1. An on-site system for treating contaminated water from a source of water contaminated with perfluoroalkyl substances (PFAS) (hereinafter referred to as "contaminated water"), A PFAS separation stage having an inlet to which a fluid can be connected to the supply source, a diluent outlet and a concentrated liquid A outlet, A nanofiltration diafiltration stage is located downstream of the PFAS separation stage and has an inlet and an outlet for concentrated liquid B that are fluidly connected to the outlet of concentrated liquid A of the PFAS separation stage. A PFAS exclusion stage is located downstream of the nanofiltration diafiltration stage and has an inlet that is fluidly connected to the outlet of the concentrated liquid B of the nanofiltration diafiltration stage, Equipped with, The elimination of PFAS related to the aforementioned source of contaminated water was carried out on-site. The PFAS separation stage comprises one or more nanofiltration modules, The nanofiltration diafiltration stage comprises one or more nanofiltration diafiltration modules, The nanofiltration diafiltration stage generates concentrated solution B, which has a higher PFAS concentration than concentrated solution A, by removing NaCl or KCl from concentrated solution A. The PFAS removal stage is equipped with an electrically accelerated oxidation system, The perfluoroalkyl substance is one or more selected from the group consisting of PF4A, PF5A, PF6A, PF7A, perfluorooctanoic acid (PFOA), PF4S, PF5S, PF6S, PF7S, PF8S, PF9S, and PF10S. The aforementioned contaminated water is an on-site system for treating contaminated water from a water source contaminated with perfluoroalkyl substances (PFAS), having a PFAS concentration of 0.1 to 100 ppb.

2. The on-site system according to claim 1, wherein the PFAS separation stage further comprises a granular activated carbon (GAC) electrode.

3. The on-site system according to claim 2, wherein the GAC electrode is incorporated within a first electrochemical cell.

4. The on-site system according to claim 3, wherein the other electrodes in the first electrochemical cell include platinum, graphite, or lead / lead oxide.

5. The on-site system according to claim 3, wherein the first electrochemical cell further comprises a sulfate electrolyte.

6. The on-site system according to claim 3, wherein the first electrochemical cell further comprises an ion exchange membrane separator.

7. The on-site system according to claim 3, wherein the adsorbed PFAS is desorbed from the GAC electrode by electrical activation of the first electrochemical cell.

8. The on-site system according to claim 1, wherein the PFAS separation stage further comprises a foam fractionation system.

9. The on-site system according to claim 1, wherein the electrically accelerated oxidation system comprises a second electrochemical cell.

10. The on-site system according to claim 9, wherein the second electrochemical cell is accompanied by a boron-doped diamond (BDD) electrode.

11. The on-site system according to claim 9, wherein the second electrochemical cell is accompanied by a magnesium phase titanium oxide electrode.

12. The aforementioned Magneli phase titanium oxide electrode has n = 4 to 10 Ti ｎ O ２ｎ－１ The on-site system according to claim 11, including the above.

13. The on-site system according to claim 9, wherein the electrodes of the second electrochemical cell are made of stainless steel, nickel alloy, or titanium.

14. The on-site system according to claim 9, wherein the second electrochemical cell comprises an electrolyte comprising at least one of hydroxides, sulfates, nitrates, and perchlorates.

15. The on-site system according to claim 1, wherein the PFAS removal stage is accompanied by UV persulfate treatment or plasma treatment.

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