Integration of wet air oxidation and electro-oxidation processes for destruction of per- and polyfluoroalkyl substances (pfas)

Abstract

Methods and systems for destroying per- and polyfluoroalkyl substances (PFAS) in water are provided. Water treatment methods include a wet air oxidation (WAO) treatment step followed by an electrooxidation treatment step. The disclosed methods and systems are capable of destroying PFAS present in water streams and / or adsorption media, including PFAS present in groundwater, drinking water, or industrial or municipal wastewater.

Description

Cross-references to related applications

[0001] This application claims priority and any rights to U.S. Provisional Application No. 63 / 624,919, filed January 25, 2024, the contents of which are incorporated herein by reference in their entirety. Technical Field

[0002] This disclosure relates to methods and systems for the destruction of perfluorinated and polyfluoroalkyl substances (PFAS). More specifically, this disclosure relates to a water treatment method including a wet air oxidation (WAO) treatment step upstream of an electro-oxidation treatment step. The disclosed methods and systems are capable of destroying PFAS present in water streams and / or adsorption media, including PFAS present in groundwater, drinking water, or industrial or municipal wastewater. Background Technology

[0003] Water sources, including groundwater, drinking water, and wastewater, often contain unwanted contaminants. One class of contaminants of growing concern is perfluorinated and polyfluorinated alkyl substances (“PFAS”), commonly known as “permanent chemicals.” Specifically, mitigating the impact of such contaminants on human populations by preventing the ingestion of PFAS has become a public health priority both domestically and internationally.

[0004] Conventional adsorption media technology (including) can be used For example Activated carbon or ion exchange can remove PFAS from the water stream. However, adsorption media only provide a way to remove (not destroy) PFAS from the water stream. Adsorption media contaminated with collected PFAS must then be disposed of.

[0005] Conventional methods for disposing of contaminated adsorbent media have been found to be inadequate. For example, there is no conclusive evidence that incineration effectively destroys PFAS, as data collected from samples near incinerators burning PFAS adsorbent media have shown that high concentrations of PFAS remain even after they were presumed to have been destroyed. Due to the hazardous and pervasive nature of PFAS contamination in groundwater, more common conventional methods for disposing of contaminated adsorbent media at landfills are under increasing scrutiny. For instance, it has been noted that PFAS begin to accumulate in landfill leachate over time.

[0006] Therefore, there is a need for effective methods to disrupt the PFAS present in water streams or other PFAS-contaminated adsorption media. Summary of the Invention

[0007] This document discloses methods and systems for the destruction of perfluorinated and polyfluoroalkyl substances (PFAS). These methods and systems include a wet air oxidation (WAO) unit 101, an electro-oxidation unit 102, and a PFAS capture adsorption medium unit 103.

[0008] According to a first aspect of this disclosure, a method for destroying perfluorinated and polyfluoroalkyl substances (PFAS) in a flowable stream is disclosed. The method includes: (a) directing an inlet stream 20 into a wet air oxidation (WAO) unit 101, the inlet stream 20 comprising water, solids, and PFAS, wherein the WAO unit 101 dissolves a portion of the solids in the inlet stream 20 to provide a WAO effluent stream 22; (b) directing the WAO effluent stream 22 into an electro-oxidation unit 102; (c) applying an electric current to the electro-oxidation unit 102 to oxidize at least a portion of the PFAS in the WAO effluent stream 22 to provide an electro-oxidized effluent stream 26; and (d) directing the electro-oxidized effluent stream 26 into a PFAS-capture adsorption medium unit 103, wherein the PFAS-capture adsorption medium unit 103 removes at least a portion of the PFAS from the electro-oxidized effluent stream to produce a treated outlet stream 34.

[0009] In the second aspect of this disclosure, unless otherwise stated, it may be combined with any other aspect listed herein, wherein the solid of the inlet flow 20 includes an adsorbent medium.

[0010] In a third aspect of this disclosure, unless otherwise stated, it may be combined with any other aspect listed herein, and the method further includes directing at least a portion of the WAO outflow stream 22 back to the WAO unit 101 as a recirculated stream 24 for WAO processing.

[0011] In the fourth aspect of this disclosure, unless otherwise stated, it may be combined with any other aspect listed herein, in which a majority of the WAO outflow stream 22 is directed back to WAO unit 101 as a recirculated stream 24 for WAO processing.

[0012] In the fifth aspect of this disclosure, unless otherwise stated, it may be combined with any other aspect listed herein, the method further comprising directing at least a portion of the electro-oxidation effluent 26 back to the WAO unit 101 as a recirculation stream 28 for the electro-oxidation treatment.

[0013] In the sixth aspect of this disclosure, unless otherwise stated, it may be combined with any other aspect listed herein, such as the electro-oxidation recycle stream 28 combined with the WAO recycle stream 24.

[0014] In the seventh aspect of this disclosure, unless otherwise stated, it may be combined with any other aspect listed herein, the method further comprising guiding a captured PFAS adsorption medium stream 32 from the captured PFAS adsorption medium unit 103 to the WAO unit 101.

[0015] In the eighth aspect of this disclosure, unless otherwise stated, it may be combined with any other aspect listed herein, the method further comprising directing the WAO effluent stream 22 to a separator unit 504, wherein the separator unit 504 is located downstream of the WAO unit 101 and upstream of the electro-oxidation unit 102.

[0016] In the ninth aspect of this disclosure, unless otherwise stated, it may be combined with any other aspect listed herein, wherein separator unit 504 separates at least a portion of PFAS from WAO effluent stream 22, and wherein separator unit 504 provides separate effluent streams including concentrated electro-oxidation inlet stream 52 and raffinate stream 54.

[0017] In the tenth aspect of this disclosure, unless otherwise stated, it may be combined with any other aspect listed herein, wherein the concentrated electro-oxidation inlet flow 52 is directed to the electro-oxidation unit 102.

[0018] In the eleventh aspect of this disclosure, unless otherwise stated, it may be combined with any other aspect listed herein, wherein the raffinate stream 54 is directed to the PFAS-captured adsorption medium unit 103.

[0019] In the twelfth aspect of this disclosure, unless otherwise stated, it may be combined with any other aspect listed herein, wherein at least a portion of the recycle stream 28 of the electro-oxidation treatment is directed for processing in the separator unit 504.

[0020] According to the thirteenth aspect of this disclosure, a system for destroying perfluorinated and polyfluoroalkyl substances (PFAS) is disclosed. The system includes: (a) a wet air oxidation (WAO) unit 101 configured to dissolve a portion of solids in an inlet stream 20, the inlet stream 20 comprising water, solids, and PFAS; (b) an electro-oxidation unit 102 located downstream of the WAO unit 101, wherein the electro-oxidation unit 102 is configured to receive a WAO effluent stream 22 and provide an electro-oxidation effluent stream 26; (c) a device for providing current to the electro-oxidation unit 102, wherein the current is sufficient to promote the oxidation of at least a portion of the PFAS in the WAO effluent stream 22 within the electro-oxidation unit 102; and (d) a PFAS-capturing adsorption medium unit 103 located downstream of the electro-oxidation unit 102, wherein the PFAS-capturing adsorption medium unit 103 is configured to remove at least a portion of the PFAS from the electro-oxidation effluent stream 26 to produce a treated outlet stream 34.

[0021] In the fourteenth aspect of this disclosure, unless otherwise stated, it may be combined with any other aspect listed herein, wherein the solid of the inlet flow 20 includes an adsorbent medium.

[0022] In the fifteenth aspect of this disclosure, unless otherwise stated, it may be combined with any other aspect listed herein, the system further includes a WAO processing recirculation flow 24 configured to flow from a point downstream of WAO unit 101 to a point upstream of WAO unit 101.

[0023] In the sixteenth aspect of this disclosure, unless otherwise stated, it may be combined with any other aspect listed herein, the system further includes an electro-oxidation recirculation flow 28 configured to flow from downstream of the electro-oxidation unit 102 to the WAO unit 101.

[0024] In the seventeenth aspect of this disclosure, unless otherwise stated, it may be combined with any other aspect listed herein, the system further includes a captured PFAS adsorption medium stream 32, which is directed to flow from the captured PFAS adsorption medium unit 103 to the WAO unit 101.

[0025] In the eighteenth aspect of this disclosure, unless otherwise stated, it may be combined with any other aspect listed herein, and the system further includes a separator unit 504 located upstream of the electro-oxidation unit 102 and downstream of the WAO unit 101.

[0026] In the nineteenth aspect of this disclosure, unless otherwise stated, it may be combined with any other aspect listed herein, wherein the separator unit 504 is configured to separate at least a portion of the PFAS from the WAO effluent stream 22.

[0027] In the twentieth aspect of this disclosure, unless otherwise stated, it may be combined with any other aspect listed herein, wherein the concentrated electro-oxidation inlet stream 52 is configured to flow from the separator unit 504 to the electro-oxidation unit 102.

[0028] In the twenty-first aspect of this disclosure, unless otherwise stated, it may be combined with any other aspect listed herein, wherein the raffinate stream 54 is configured to flow from the separator unit 504 to the PFAS-captured adsorption medium unit 103.

[0029] In the twenty-second aspect of this disclosure, unless otherwise stated, it may be combined with any other aspect listed herein, wherein the recirculating flow 56 for further separation of the electro-oxidation treatment is configured to flow from downstream of the electro-oxidation unit 102 to the separator unit 504. Attached Figure Description

[0030] The advantages of the inventive concept will become apparent upon consideration of the following detailed disclosure, particularly when taken in conjunction with the accompanying drawings, wherein: Figure 1A flow diagram of an exemplary water treatment system according to this disclosure is shown; and Figure 2 A flow chart of another embodiment of a water treatment system according to the present disclosure is shown. Detailed Implementation

[0031] This document discloses methods and systems for the destruction of perfluorinated and polyfluoroalkyl substances (PFAS). While certain embodiments of the methods and systems are described in detail in this disclosure, this disclosure should be considered exemplary and is not intended to be limited to the disclosed embodiments.

[0032] As used herein, the term “COD” or “chemical oxygen demand” refers to a measure of the amount of oxygen required to completely oxidize organic and inorganic pollutants in wastewater. COD measurements include bioinstable, bioinhibitory, and biorecalcitrant compounds. Unless otherwise stated, it should be understood that COD does not refer to the presence or measurement of PFAS pollutants, as these specific compounds are described separately herein.

[0033] As used herein, the term "unit" generally refers to a unit operation. A unit operation can be one or more fundamental operations in a process. A unit may have one or more subunits (or subsystems). Unit operations may involve physical changes or chemical transformations, such as separation, crystallization, evaporation, filtration, polymerization, isomerization, other reactions, or combinations thereof. A unit may include one or more individual components.

[0034] As used herein, the terms “water” and “water flow” encompass any water to be treated that flows or is otherwise introduced into a water treatment system; such as surface water, groundwater, and wastewater flows from industrial, agricultural, and municipal sources; water to be treated containing contaminants such as biodegradable materials, inorganic or unstable organic compounds that can be broken down by bacteria, biodegradable compounds, and / or bioinhibitory compounds.

[0035] The methods and systems of this disclosure will be further described with reference to the accompanying drawings. It should be understood that the features shown in the drawings are not necessarily drawn to scale. In the drawings, the direction of fluid flow is indicated by arrows. Fluid can be directed from one unit to another, for example, with the aid of valves and fluid flow systems. As those skilled in the art will understand, such fluid flow systems may include compressors and / or pumps, as well as control systems for regulating fluid flow.

[0036] refer to Figure 1 The diagram shows a flow chart of a water treatment system 100. The system 100 includes a wet air oxidation (WAO) unit 101, an electro-oxidation unit 102, and a PFAS-captured adsorption medium unit 103.

[0037] Generally, the inlet flow 20 entering the water treatment system 100 includes contaminants. in This includes perfluorinated and polyfluoroalkyl substances (PFAS). The inlet stream 20 may include water, including groundwater, drinking water, or industrial or municipal wastewater.

[0038] The inlet stream 20 may alternatively or additionally include an adsorption medium contaminated with PFAS. As is known in the art, conventional adsorption media techniques (including...) can be used. For example PFAS are removed (i.e., collected) from the water stream by activated carbon or ion exchange. Therefore, the inlet stream 20 may include PFAS removed from an external or upstream water treatment source (…). Figure 1 The adsorption medium for PFAS contamination (not shown in the figure).

[0039] like Figure 1 As shown, a wet air oxidation (WAO) unit 101 is configured to receive an inlet stream 20. The WAO unit 101 includes one or more dedicated reactor vessels and provides aqueous phase oxidation of unwanted components with an oxidant at elevated temperature and pressure. The oxidant may contain molecular oxygen from an oxygen-containing gas, including, for example, pressurized oxygen-containing gas supplied by a compressor. The oxidant may flow through a heat exchanger at the inlet stream 20. Figure 1 (Not shown in the image) is added to the inlet stream 20 before, during, or after. Therefore, the inlet stream 20 is treated in the WAO unit 101 via a hydrothermal process to dissolve and reduce the adsorption medium (not shown in the image) in the inlet stream 20. For example The COD associated with the oxidation process (using activated carbon or ion exchange media) is as follows: Dissolved organic components include carbon dioxide, water, and biodegradable short-chain organic acids (such as acetic acid). Inorganic components, including sulfides, thiols, and cyanides, may also be oxidized. A specific operational benefit of the disclosed WAO process is the recovery of heat released from the exothermic reaction that occurs during oxidation from the adsorption medium, which can reduce operating costs. In some aspects, the oxidation process in the WAO unit is carried out at temperatures ranging from 150°C to 300°C, including 175°C to 300°C, including 200°C to 280°C, including 200°C to 260°C, including below 260°C. In some respects, the oxidation process in the WAO unit is carried out at pressures ranging from 300 psig to 3,000 psig, including 300 psig to 2,000 psig, including 500 psig to 1,000 psig, including less than 1,000 psig, including 600 psig to 900 psig, including 800 psig.

[0040] Continue to refer to Figure 1The WAO effluent stream 22 leaves the WAO unit 101 and is supplied to the electro-oxidation unit 102. In some aspects, a portion of the WAO effluent stream 22 can be redirected back to the WAO unit 101 for further processing as a WAO treatment recirculation stream 24. The WAO treatment recirculation stream 24 can constitute any portion of the WAO effluent stream 22. In some aspects, the WAO treatment recirculation stream 24 constitutes the majority of the WAO effluent stream 22, with only a small portion of the WAO effluent stream 22 being directed to the electro-oxidation unit 102. Therefore, it has been found that the recirculation of the WAO treatment recirculation stream 24 optimizes the flow into the electro-oxidation unit 102 because the COD of the WAO effluent stream 22 is minimized and the PFAS concentration of the WAO effluent stream 22 is maximized. In summary, WAO treatment is used to transfer PFAS contaminants from the solid-phase adsorbent medium to the liquid phase ( Right now (Water-based) is used for downstream electro-oxidation processing.

[0041] The electro-oxidation unit 102 is configured to break down PFAS contaminants in the WAO effluent stream 22 to a desired level. Generally, the electro-oxidation unit 102 includes sub-components (not shown). in The system includes pumps, filters, coolers, a power source, and a reactor. Pumps (if used) can be any type of pump operable to draw fluid from an inlet or source and direct it through the electro-oxidation process at a desired flow rate and pressure. Filters can be positioned to remove larger contaminants and debris from the fluid before it passes through the cooler. The cooler operates to cool the fluid to a desired temperature before it is directed to the reactor. The reactor uses conductive, freestanding, substrate-free synthetic diamond electrodes. For example, the electro-oxidation unit 102 can incorporate one or more boron-doped diamond (BDD) electrodes. Current is supplied to the electrodes by a power source.

[0042] Generally, electro-oxidation is a process in which water flows between electrodes while an electric current passes through them. As the current jumps between the electrodes and through the water, it breaks down some of the water molecules, forming hydroxyl radicals (OH-) and hydrogen ions (H+). Hydroxyl radicals are strong oxidizing agents capable of oxidizing and mineralizing organic molecules they encounter, including fluorocarbons. Thus, PFAS are converted into carbon dioxide and fluoride ions, thereby removing contaminants from the inlet stream. Electro-oxidation has been shown to destroy PFAS of all different carbon lengths.

[0043] The extent to which PFAS are destroyed and COD is reduced during the electro-oxidation process directly corresponds to the amount of current density and time required for the electro-oxidation operation. According to this disclosure, the electro-oxidation process operates at 5,000 A / m². 2 Up to 50,000 A / m 2 The tests were conducted at current densities including 5,000 A / m. 2Up to 30,000 A / m 2 Including 5,000 A / m 2 Up to 10,000 A / m 2 Including 5,000 A / m 2 Up to 7,500 A / m 2 Including 5,000 A / m 2 The electro-oxidation step can be operated as a continuous process or as a batch process.

[0044] The characteristics of the electro-oxidation process occurring within the electro-oxidation unit 102 are further described in co-pending U.S. Patent Application Publication No. 2023 / 0024923, which is incorporated herein by reference in its entirety.

[0045] Continue to refer to Figure 1 The electro-oxidation effluent 26 exits the electro-oxidation unit 102. For example, after the COD concentration has decreased to a level where mass transfer becomes limited during the electro-oxidation process (by a non-limiting example, COD < 3,000 mg / L), the electro-oxidation effluent 26 can be sent from the electro-oxidation unit 102. According to this disclosure, a portion of the electro-oxidation effluent 26 can be redirected back to the WAO unit 101 as a recirculation stream 28 for the electro-oxidation process. The recirculation stream 28 for the electro-oxidation process can be combined with the recirculation stream 24 for the WAO process for further processing in the WAO unit 101. Alternatively or additionally, the recirculation stream 28 for the electro-oxidation process can proceed directly to further processing in the WAO unit 101.

[0046] The remaining portion of the electro-oxidation effluent 26 ( Right now, The portion of the electro-oxidation effluent 26 that does not constitute the recycle stream 28 of the electro-oxidation treatment is directed to the PFAS adsorption medium unit 103 as the discharge stream 30 for electro-oxidation treatment.

[0047] The PFAS capture adsorption medium unit 103 includes any suitable adsorption medium, including those known in the water treatment field, such as activated carbon or ion exchange. The adsorption medium of the PFAS capture adsorption medium unit 103 removes PFAS from the effluent stream 30 from the inlet electro-oxidation treatment. According to this disclosure, the effluent from the PFAS capture adsorption medium unit 103 includes a treated effluent stream 34, which can be disposed of to a wastewater treatment plant. According to this disclosure, the PFAS concentration in the treated effluent stream 34 is suitable for meeting local environmental discharge standards.

[0048] In at least some aspects of this disclosure, the effluent from the captured PFAS adsorption medium unit 103 separately includes a captured PFAS adsorption medium stream 32, which can be recycled back into the system upstream of the WAO unit 101. Therefore, system 100 not only provides treatment for external PFAS adsorption medium present in the inlet stream 20, but also provides a closed-system PFAS destruction method for the saturated adsorption medium of the captured PFAS adsorption medium unit 103.

[0049] refer to Figure 2 A flow diagram of a water treatment system 200 is shown. System 200 includes... Figure 1 In each material component of system 100, a separator unit 504 is added.

[0050] like Figure 2 As shown, the WAO effluent 22 exits the WAO unit 101 and is supplied to the separator unit 504. The separator unit 504 is used to concentrate the WAO effluent 22 prior to processing in the electro-oxidation unit 102. The separator unit 504 may include devices suitable for reverse osmosis or foam fractionation. It should be understood that the separator unit 504 can be replaced by any device suitable for facilitating the separation of some portions of PFAS from some portions of soluble COD in the WAO effluent 22. Thus, the separator unit 504 improves the efficiency of PFAS destruction in the downstream electro-oxidation unit 102 by eliminating a portion of the COD. It should be understood that even in embodiments that do not include a stand-alone separation unit, incorporating a separation method prior to electro-oxidation is within the scope of this disclosure. For example, the wet air oxidation (WAO) unit 101 may incorporate an additional separation step. Additionally or separately, the electro-oxidation unit 102 may incorporate an additional separation step.

[0051] Further reference Figure 2 The concentrated electro-oxidation inlet stream 52 exits the separator unit 504 and is directed to the electro-oxidation unit 102 to break down the PFAS contaminants in the concentrated electro-oxidation inlet stream 52 to the desired level. The electro-oxidation process is as previously described. Figure 1 As described for the electro-oxidation unit 102.

[0052] In addition to the concentrated electro-oxidation inlet stream 52, the concentration process within separator unit 504 can also generate raffinate stream 54. Raffinate stream 54 can be directly routed to the PFAS capture adsorption medium unit 103 for further processing, or it can optionally be combined with the discharge stream 30, which has undergone electro-oxidation treatment upstream of the PFAS capture adsorption medium unit 103.

[0053] Finally, continue to refer to Figure 2A portion of the electro-oxidation effluent 26 can be redirected back to the WAO unit 101 as a recirculated flow 28 for the electro-oxidation process. Alternatively or additionally, some or all of the recirculated flow 28 for the electro-oxidation process can be redirected downstream of the wet air oxidation (WAO) unit 101 and upstream of the separator unit 504 to allow for further processing in the separator unit 504. This recirculated flow for further separation in the electro-oxidation process... Figure 2 It is described as flow 56 in the middle.

[0054] As mentioned above, the use of adsorption media technology (including...) For example Conventional methods of removing PFAS (using activated carbon or ion exchange) have proven effective in reducing the presence of such contaminants in water streams. However, adsorption media only provide a means of removing (not destroying) PFAS from water streams. Adsorption media contaminated with collected PFAS must subsequently be disposed of, and prior to this disclosure, no effective means of selectively removing PFAS from adsorption media had been found.

[0055] Electro-oxidation is a known process for destroying PFAS contaminants in water. Right now High current density is used to destroy PFAS. However, electro-oxidation is an energy-intensive process and does not provide selective destruction of contaminants. Therefore, PFAS are destroyed along with all other contaminants in the inlet stream. Although electro-oxidation can destroy PFAS, including saturated adsorption media, on a laboratory scale (…),… Right now The inlet slurry contains both solids and PFAS-contaminated water, but single-step electro-oxidation on an industrial scale directly destroys both the adsorption medium solids and PFAS contaminants, resulting in extremely high operating costs. For example (In terms of electricity consumption) it would be economically unfeasible.

[0056] Specifically, wet air oxidation (WAO) is often proposed as a solution for PFAS contaminants in water. However, the conventional understanding in the art is that it is subcritical ( Right now Low-temperature (WAO) processing is not efficient enough in destroying PFAS. Therefore, supercritical water oxidation (SCWAO) has been found to be necessary to provide single-step WAO destruction of PFAS. Specifically, to achieve the required efficiency for PFAS destruction, SCWAO processes operate above 374°C, with some SCWAO processes requiring temperatures as high as 500°C to 650°C. Although PFAS destruction has been observed on a laboratory scale in such processes, there is not enough heat release from the SCWAO reaction to heat the fluid to these supercritical temperatures unless additional heat or fuel is added. Right now(There is almost no opportunity for heat recovery). In addition, supercritical fluids introduce manufacturing problems to the SCWAO process, including corrosiveness and a tendency to scale.

[0057] However, in this case, the inventors have surprisingly discovered that the combination of wet air oxidation upstream of electro-oxidation provides near-complete destruction of PFAS and the adsorbent medium from the inlet stream, and further offers significant processing efficiency from an economic perspective. The inventors have found that subcritical WAO processing as the first step in downstream electro-oxidation is effective, in contrast to the previously suggested single-step processing of SCWAO or electro-oxidation. These results have proven to be synergistic rather than simply additive, particularly from a manufacturing efficiency perspective. By operating the WAO process at subcritical rather than supercritical temperatures, the inventors have found that heat recovery can be applied, resulting in a more energy-efficient system overall. For example, in applications with COD above 10,000 mg / L disclosed in this disclosure, the exothermic reaction of WAO is greater than the exothermic reaction required to heat the solution to initiate the WAO reaction. The end result is a highly energy-efficient WAO step, or even the provision of manufacturing opportunities for heat output.

[0058] Furthermore, as mentioned earlier, electro-oxidation as a separate step involves high capital and operational costs in destroying the PFAS adsorption medium solid. Specifically, high current density electro-oxidation is required to fully destroy the PFAS compounds. However, utilizing the high current density required for PFAS to treat the entire inlet adsorption medium ( Right now Direct electro-oxidation of all oxidizable materials in the wastewater adsorption medium matrix is ​​very inefficient and results in excessively high energy costs. Here, by performing an upstream WAO step, the inlet stream of the high current density electro-oxidation unit contains a significantly lower concentration of excess COD associated with the adsorption medium. Therefore, the high current density electro-oxidation step is specifically designed for PFAS destruction without wasting expensive resources on COD destruction. For example ,electricity).

[0059] In summary, the inventors have found that the combination of WAO and electro-oxidation provides a flexible and cost-effective solution for destroying adsorption media containing PFAS.

[0060] The terminology set forth herein is used only for the description of embodiments and should not be construed as limiting this disclosure as a whole. All references to a singular feature or limitation of this disclosure shall include the corresponding plural feature or limitation, and vice versa, unless otherwise specified or clearly implied by the context in which the reference is made. Unless otherwise stated, “a,” “an,” “the,” and “at least one” are used interchangeably. Furthermore, as used in the specification and appended claims, the singular forms “a” and “the” include their plural forms, unless the context clearly indicates otherwise.

[0061] With regard to the term "includes / including" as used in the specification or claims, it is intended to be included in a manner similar to the term "comprising," as interpreted when the term is used as a transition word in the claims. Furthermore, with regard to the use of the term "or" (e.g., A or B), it is intended to mean "A or B or both." The term "A or B only but not both" will be used when the applicant intends to indicate "only A or B but not both." Therefore, the use of the term "or / or" herein is inclusive, not exclusive.

[0062] All combinations of methods or process steps used herein may be performed in any order unless otherwise stated or clearly implied by the context of performing the referenced combinations.

[0063] All ranges and parameters disclosed herein, including but not limited to percentages, parts, and ratios, should be understood to encompass any and all subranges assumed and included therein, as well as every number between the endpoints. For example, the stated range “1 to 10” should be considered to include any and all subranges that begin with a minimum value of 1 or greater and end with a maximum value of 10 or less (e.g., 1 to 6.1 or 2.3 to 9.4), as well as every integer contained within that range (1, 2, 3, 4, 5, 6, 7, 8, 9, and 10).

[0064] The methods and systems disclosed herein may include, consist of, or substantially consist of the essential elements of this disclosure as described herein, as well as any additional or optional elements described herein, or may otherwise be used for water treatment applications.

[0065] According to this disclosure, various inventive concepts can be utilized in combination with each other. Furthermore, any particular feature described as relating to a specific disclosed aspect of the methods and systems of this disclosure should be interpreted as applicable to all disclosed aspects of the methods and systems of this disclosure, unless the incorporation of such particular feature would contradict the express terms of the disclosed aspect. Additional advantages and modifications will be apparent to those skilled in the art. Therefore, this disclosure, in its broader aspects, is not limited to the specific details, representative devices, or illustrative examples shown and described therein. Therefore, deviations from these details may be made without departing from the spirit or scope of the overall inventive concept.

Claims

1. A method for destroying perfluorinated and polyfluoroalkyl substances (PFAS) in a flowable stream, the method comprising: (a) The inlet stream 20 is directed into the wet air oxidation (WAO) unit 101, the inlet stream 20 comprising water, solids and PFAS, wherein the WAO unit 101 dissolves a portion of the solids in the inlet stream 20 to provide WAO effluent stream 22; (b) The WAO effluent 22 is directed to the electro-oxidation unit 102; (c) Applying an electric current to the electro-oxidation unit 102 to oxidize at least a portion of the PFAS in the WAO effluent 22 to provide the electro-oxidized effluent 26; and (d) The electro-oxidation effluent 26 is directed to a PFAS-captured adsorption medium unit 103, wherein the PFAS-captured adsorption medium unit 103 removes at least a portion of the PFAS from the electro-oxidation effluent to produce a treated effluent 34.

2. The method according to claim 1, wherein the solid in the inlet stream 20 comprises an adsorbent medium.

3. The method according to claim 1 or claim 2, further comprising guiding at least a portion of the WAO effluent 22 back to the WAO unit 101 as a recirculated flow 24 for WAO processing.

4. The method of claim 3, wherein a majority of the WAO effluent 22 is directed back to the WAO unit 101 as a recirculated flow 24 of the WAO processing.

5. The method according to any one of claims 1 to 4, further comprising guiding at least a portion of the electro-oxidation effluent 26 back to the WAO unit 101 as a recirculation stream 28 for electro-oxidation treatment.

6. The method of claim 5, wherein the recycle stream 28 of the electro-oxidation treatment is combined with the recycle stream 24 of the WAO treatment.

7. The method according to any one of claims 1 to 6, further comprising guiding a captured PFAS adsorption medium stream 32 from the captured PFAS adsorption medium unit 103 to the WAO unit 101.

8. The method according to any one of claims 1 to 7, further comprising guiding the WAO effluent 22 to a separator unit 504, wherein the separator unit 504 is located downstream of the WAO unit 101 and upstream of the electro-oxidation unit 102.

9. The method of claim 8, wherein the separator unit 504 separates at least a portion of the PFAS from the WAO effluent stream 22, and wherein the separator unit 504 provides a separate effluent stream comprising a concentrated electro-oxidation inlet stream 52 and a raffinate stream 54.

10. The method of claim 9, wherein the concentrated electro-oxidation inlet stream 52 is directed to the electro-oxidation unit 102.

11. The method of claim 9, wherein the raffinate stream 54 is directed to the captured PFAS adsorption medium unit 103.

12. The method according to any one of claims 8 to 11, wherein at least a portion of the recirculated stream 28 of the electro-oxidation treatment is directed for processing in the separator unit 504.

13. A system for destroying per- and polyfluoroalkyl substances (PFAS), the system comprising: (a) Wet air oxidation (WAO) unit 101, the WAO unit being configured to dissolve a portion of solids in an inlet stream 20, the inlet stream 20 comprising water, the solids and PFAS; (b) Electro-oxidation unit 102, located downstream of WAO unit 101, wherein the electro-oxidation unit 102 is configured to receive WAO effluent 22 and provide electro-oxidation effluent 26. (c) A device for supplying current to the electro-oxidation unit 102, wherein the current is sufficient to promote the oxidation of at least a portion of the PFAS in the WAO effluent stream 22 within the electro-oxidation unit 102; and (d) A PFAS-captured adsorption medium unit 103 is located downstream of the electro-oxidation unit 102, wherein the PFAS-captured adsorption medium unit 103 is configured to remove at least a portion of the PFAS from the electro-oxidation effluent 26 to produce a treated effluent 34.

14. The system of claim 13, wherein the solid in the inlet flow 20 comprises an adsorbent medium.

15. The system of claim 13 or claim 14, further comprising a WAO processing recirculation flow 24, the WAO processing recirculation flow being configured to flow from a point downstream of the WAO unit 101 to a point upstream of the WAO unit 101.

16. The system according to any one of claims 13 to 15, further comprising a recirculating flow 28 for electro-oxidation treatment, the recirculating flow being configured to flow from a point downstream of the electro-oxidation unit 102 to the WAO unit 101.

17. The system according to any one of claims 13 to 16, further comprising a captured PFAS adsorption medium stream 32, the captured PFAS adsorption medium stream being directed to flow from the captured PFAS adsorption medium unit 103 to the WAO unit 101.

18. The system according to any one of claims 13 to 17, further comprising a separator unit 504 located upstream of the electro-oxidation unit 102 and downstream of the WAO unit 101.

19. The system of claim 18, wherein the separator unit 504 is configured to separate at least a portion of the PFAS from the WAO effluent stream 22.

20. The system of claim 18 or claim 19, wherein the concentrated electro-oxidation inlet stream 52 is configured to flow from the separator unit 504 to the electro-oxidation unit 102.

21. The system according to any one of claims 18 to 20, wherein the raffinate stream 54 is configured to flow from the separator unit 504 to the captured PFAS adsorption medium unit 103.

22. The system according to any one of claims 18 to 21, wherein the recirculation flow 56 for further separation of the electro-oxidation treatment is configured to flow from a point downstream of the electro-oxidation unit 102 to the separator unit 504.

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