Destruction of polyfluoroalkyl substances using enzymes and inorganic catalysts

Abstract

Compositions, systems, and methods are described to remove per-and polyfluoroalkyl substances (PFAS) from water. The disclosed methods remove PFAS by mixing contaminated water with a enzyme along with a non-toxic metal catalyst, filtering the mixture, and recovering the metal catalyst from the retentate stream. The disclosure includes methods of using the catalyst to improve the reaction performance while minimizing the total catalyst mass needed for treatment. Unlike competing methods, the disclosed method produces little or no residual.

Description

Destruction of Polyfluoroalkyl Substances Using Enzymes and Inorganic CatalystsCross-Reference to Related Applications

[0001] The present application claims priority to U.S. Provisional Patent Application Serial No. 63 / 673,838, filed July 22, 2024, the content of which is hereby incorporated herein by reference in its entirety.Technical Field

[0002] The present disclosure removes per-and polyfluoroalkyl substances (PF AS) from water using enzymes, and non-toxic metal catalysts.Background Art

[0003] PFAS substances were introduced into consumer products in the 1930s and at the time were believed to be non-toxic. These chemicals were known for their ability to be stable in the environment. Today PFAS substances are considered forever chemicals due to their inability to break-down in the environment. Recently these chemicals have been found to negatively affect living organisms at extremely low levels (less than 20 parts per trillion).

[0004] PFAS ingredients have been used in many consumer and commercial products including firefighting foams, fire retardants, water repellents, and as surfactants.

[0005] Current data indicates that more than 45% of the nation’s tap water is estimated to have one or more types of chemicals known as PFAS (USGS July 5, 2023).Summary of the Embodiments

[0006] The present disclosure is directed to remove per-and polyfluoroalkyl substances (PFAS) from water. PFAS is removed by mixing contaminated water with enzymes along with non-toxic metal catalysts. The disclosure includes methods of using the catalyst to improve the reaction performance while minimizing the total catalyst mass needed for treatment. The ratio of PFAS to enzyme may be 3 pg to 3,000,000 pg and the inorganic catalyst may be powdered platinum with a weight concentration in the reactor of 8 g platinum in 1,000 g water.

[0007] The unique attribute to the disclosure is it produces little to no residual. Sorption methods for removing PF AS include ion exchange and activated carbon. Both methods produce a significant residual that requires further treatment / destruction. This method produces between 0.1% to 1% waste, depending on the PFAS feed concentration.

[0008] According to some embodiments, a method is disclosed of removing organofluorine compounds from contaminated water comprising:(a) mixing the contaminated water with an inorganic catalyst and with an enzyme, wherein the inorganic catalyst is selected from the group consisting of a metal, a metal cation, an organometallic compound, and combinations thereof;(b) filtering the mixture by ultrafiltration to obtain a permeate stream and a retentate stream, wherein the organofluorine compounds present in the permeate stream is reduced by at least 50 wt% compared to the amount present in the contaminated water; and(c) recovering the enzyme from the retentate stream.

[0009] In accordance with another embodiment, the disclosure provides A method of removing organofluorine compounds from contaminated water, the method comprising: a) mixing the contaminated water with an enzyme; b) passing the mixture through a catalytic reactor, the catalytic reactor comprising a scaffold comprising an inorganic catalyst selected from the group consisting of a metal, a metal cation, an organometallic compound, and combinations thereof; c) filtering the mixture passed through the catalytic reactor by ultrafiltration to obtain a permeate stream and a retentate stream, wherein the organofluorine compounds present in the permeate stream are reduced by at least 50 wt% compared to the amount present in the contaminated water; and d) recovering the enzyme from the retentate stream.

[0010] In accordance with yet another embodiment, the disclosure provides a system for removing organofluorine compounds from a stream of water, the system comprising: (a) a water supply feed to provide the stream of water; (b) an injection device, downstream of the feed water supply mechanism, configured to deliver enzyme into the stream of water; (c) a catalytic reactor, having an inorganic catalyst disposed therein, downstream of the injection device, configured to receive the stream of water so that the stream of water mixes with the inorganic catalyst; (d) an ultrafiltration device, configured to receive an output of the catalytic reactor, having an ultrafiltration membrane, the ultrafiltration membrane configured to separate the enzyme and anyorganofluorine compounds bound to the enzyme from the water stream, so as to produce (i) a permeate stream in which the organofluorine compounds arc reduced at least 50 wt% compared to the amount present in the stream of water, and (ii) a retentate stream comprising free enzyme and enzyme bound to the organofluorine compounds; and (e) a purge control valve configured to (i) recirculate a first portion of the retentate stream into the stream of water, upstream of the catalytic reactor, and (ii) divert a second portion of the retentate stream as byproduct to a waste vessel. In some embodiments, the inorganic catalyst is provided on a scaffold within the catalytic reactor.

[0011] According to some such embodiments, the organofluorine compounds include polyfluoroalkyl substances and / or perfluoroalkyl substances.

[0012] According to some embodiments, the enzyme is chosen from the group consisting of amylase, glutathione-S-transferase, alanine transaminase, aspartate transaminase, and combinations thereof. In some such embodiments, the enzyme is a food-grade amylase. According to some embodiments, the inorganic catalyst is a metal. In some such embodiments, the metal is selected from the group consisting of Fe, Mg, Cr, Ti, Mn, Au, Ag, Pt, and combinations thereof. In some such embodiments, the metal is Pt.

[0013] According to some embodiments, the metal is prepared to have a high surface area. In some embodiments, the method is performed at a temperature between 1 and 99 degrees Celsius.

[0014] Further disclosed is a composition comprising an inorganic catalyst and a enzyme, the composition having efficacy for removing organofluorine compounds from water. For some such compositions, the enzyme is an amylase. For some such compositions the organofluorine compounds include compounds selected from the group consisting of perfluoroalkyl substances, polyfluoroalkyl substances, and combinations thereof. For some compositions the inorganic catalyst is a metal selected from the group consisting of Fe, Mg, Cr, Ti, Mn, Au, Ag, Pt, and combinations thereof. In a specific composition, the metal is Pt.

[0015] Further disclosed is a reactor design that allows the enzyme and catalyst to capitalize on using proximity as a means of accelerating reactions by developing organic scaffolds that colocate a catalyst and starting material. The generic structure of a scaffolding catalyst has a catalyst-binding site (or bound catalytic residue) and a substrate-binding site. The key insight for this concept is that substrate binding does not require simultaneous activation of afunctional group; therefore, the scaffolds can be applied potentially to a wide range of transformations to significantly accelerate the reaction rates.Brief Description of the Drawings

[0016] The foregoing features of embodiments will be more readily understood by reference to the following detailed description, taken with reference to the accompanying drawings, in which:

[0017] Fig. 1 is a schematic showing operation of a PFAS treatment system, according to an aspect of the present disclosure.Detailed Description of Specific Embodiments

[0001] Unless defined otherwise, all technical and scientific terms used herein have the meaning commonly understood by a person skilled in the art to which this invention belongs.

[0002] The terms “a” and “an” and “the” and similar reference used in the context of describing the invention (especially in the context of the claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.

[0003] Fig. 1 shows an embodiment of the present disclosure for removing polyfluoroalkyl substances (PFAS) from water. Water samples containing PFAS are treated using a enzyme in the presence of a non-toxic metal catalyst. Water samples with concentrations of PFAS from 3 parts per trillion (ppt) to 5,000 parts per trillion (ppt) were treated. Ultrafilter permeate stream treatment removal performance is 99% PFAS removed or higher.

[0004] Available enzymes that can be employed for treatment include but are not limited to amylase, glutathione-S-transferase, alanine transaminase, aspartate transaminase, and enzymes containing amino acid combinations of aspartic acid, histidine, and lincomycin.

[0005] Available non-toxic metal catalysts that may be employed for treatment include iron, magnesium, chrome, titanium, manganese, gold, silver, and platinum.

[0006] In some embodiments, water samples containing PFAS may be mixed with a enzyme and a non-toxic metal catalyst and fdtered via an ultrafilter. Non-toxic metallic catalyst is prepared to have a high surface area. PFAS compounds are both decomposed and chemically bound with the enzyme. After mixing, liquid is pumped to an ultrafilter where the permeate PFAS concentration is less than 1 % of the feed stream and the enzyme and other PFAS byproducts are recovered in the ultrafilter reject (retentate). In some embodiments, reject is 0.1 to 1% (wt.) of the feed stream mass. Treatment can be performed at temperatures from 1 degree Celsius to 99 degrees Celsius.Process for Applying the Treatment Method

[0007] In some embodiments, a process is designed for production of PFAS free water, by continuous or batch methods. Reagent and catalyst spatial distribution is used to increase the reaction kinetics performance. Typically, waters contaminated with PFAS have PFAS concentrations of 1 to 3000 parts per trillion. An excess dose of enzyme is used to improve the probability of contact with the PFAS compounds. A reactor is designed to maximize available reaction sites for the PFAS-enzyme reaction, such as a fluidized bed reactor, powdered metals, or and the like.

[0008] In some embodiments, a reactor system and process employing a non-toxic metal catalyst may be employed wherein the reactor system comprises a vertical reactor having a scaffolding medium permeable distribution plate towards the base thereof, a supply line to supply fluidizing medium consisting of water, contaminant, and well distributed enzyme to the base of the reactor, a non-toxic metal catalyst substrate through which fluidizing medium attaches, and a substrate recovery screen and / or disengagement zone to prevent substrate loss. Enzyme product recovery means to recover enzyme product after the reactor is employed.Examples

[0009] A water sample contaminated with PFAS (total PFAS concentration is 5 to 3000 ppt) is added to a 1,000 mL Erlenmeyer Flask. Standard treatment conditions include 5 g of amylase, 8 g of powdered platinum, a four-hour retention time, and mixed at room temperature.The mixture is pumped through an ultrafilter and the filtered water is analyzed for PFAS chemicals using EP A (Environmental Protection Agency) test method 537.1.Example 1

[0010] Raw water from a local source, previously used for drinking water, in Burlington Massachusetts was recorded to have 32.34 ng / L of regulated PFAS contaminants and 8.62 ng / L of unregulated PFAS contaminants. Treated under standard conditions, the total amount of regulated contaminants decreased by 100% and the total amount of unregulated contaminants decreased by 69.4%. Notable data is highlighted in Table 1. These results have been reproduced.Table 1: Comparison of PFAS Concentrations between Raw and Treated WaterExample 2

[0011] Different retention times for treatment include 24 hours, 8 hours, 4 hours, and 1 hour. Table 2 includes data collected from each retention time variable. Remaining standardtreatment conditions were constant. As time decreases, the amount of unregulated PFAS contaminants increases, indicating a correlation between time and treatment. In all treated samples, regulated contaminants are reported as non-detected. This observation indicates that while time has some impact, it is not a determining factor.Table 2: Comparison of PFAS Concentration between Trials with Different Retention TimesExample 3

[0012] Raw water from a local source, previously used for drinking water, in Burlington Massachusetts was recorded to have 32.34 ng / L of regulated PFAS contaminants, and 8.62 ng / L of unregulated PFAS contaminants. The sample was treated with 8 g of platinum or 0 g of platinum to observe the importance of a metal catalyst, specifically platinum. Remaining standard treatment conditions were constant. Table 3 includes an analysis collected from a raw sample, the trial with platinum, and the trial without platinum. The trial without platinum has atotal concentration of regulated contaminants higher than the EPA limit, therefore, platinum is an important reactant to facilitate this treatment. Furthermore, the total amount of regulated contaminants decreased by 100% in the trial with platinum and total amount of regulated contaminants decreased by 34.8% in the trial without platinum.Table 3: Comparison of PFAS Concentration between Trials with Different Concentrations of PlatinumExample 4

[0013] This example validates that the PFAS molecules are not too large to permeate through an ultrafilter, as well as determines if the PFAS is bonding to the enzyme and remaining in the retentate instead of breaking down. The total amount of regulated contaminants decreased by 100% in the permeate and total amount of regulated contaminants decreased by 94.1% in the retentate. While the retentate has contaminants not present in the permeate, the high percent decrease in the retentate indicates that the majority of PFAS are not captured in the retentate.Table 4 contains the analysis data from a raw sample, treated permeate, and treated retentate stream.Table 4: PFAS Concentration in Treated Permeate and Treated RetentateExample 5

[0014] Additional testing was done to confirm whether PFAS remains as an organic compound. Raw water from a local source in Burlington, Massachusetts was recorded to have PFAS contamination above EPA limits. Water was treated under standard conditions. A raw and treated water sample were analyzed for Extractable Organic Fluorine (EOF). Table 5 highlights the analysis data. The raw sample was found to have 2.66ug / L of organic fluorine. The treated sample was found to have Oug / L of organic fluorine. These results validate that the treatment process cleaves the molecule in such a way that the fluorine element is no longer part of an organic molecule but instead present in some form of an inorganic compound (ex. fluoride ion).Table 5: Fluorine Concentration in Raw and Treated Water

[0015] Fluorine Analysis was performed again using a sample with higher PF AS concentrations. Raw water from Fort Devens Air Force Base was found to have 2717.5 ng / L of regulated PF AS contaminates, and 519.7 ng / L of unregulated PF AS contaminates. A raw sample, permeate treated sample, and reject treated sample were sent for analysis. Table 6 includes the analysis data. The raw sample was found to have 5.18 ug / L organic fluorine and both treated samples had no detection for organic fluorine.Table 6: Fluorine Concentration in Raw and Treated Water

[0016] Various embodiments of the present invention may be characterized by the potential claims that follow. These potential claims form a part of the written description of this provisional application. Accordingly, subject matter of the following potential claims may be presented as actual claims in later proceedings involving this application or any application claiming priority based on this application. Inclusion of such potential claims should not be construed to mean that the actual claims do not cover the subject matter of the potential claims. Thus, a decision to not present these potential claims in later proceedings should not be construed as a donation of the subject matter to the public. Moreover, any changes made to these potential claims do not limit the scope of the actual claims in later proceedings involving this application or any application claiming priority based on this application.

[0017] Without limitation, potential subject matter that may be claimed (prefaced with the letter “P” so as to avoid confusion with the actual claims presented subsequently).Potential claims:P 1. A method of removing organo fluorine compounds from contaminated water, the method comprising: a) mixing the contaminated water with an enzyme;b) passing the mixture through a catalytic reactor, the catalytic reactor comprising a scaffold comprising an inorganic catalyst selected from the group consisting of a metal, a metal cation, an organometallic compound, and combinations thereof; c) filtering the mixture passed through the catalytic reactor by ultrafiltration to obtain a permeate stream and a retentate stream, wherein the organofluorine compounds present in the permeate stream are reduced by at least 50 wt% compared to the amount present in the contaminated water; and d) recovering the enzyme from the retentate stream.P2. The method of potential claim Pl wherein the organofluorine compounds include polyfluoroalkyl substances.P3. The method of potential claim P 1 wherein the organofluorine compounds include perfluoroalkyl substances.P4. The method of any one of potential claims Pl to P3, wherein the enzyme is selected from the group consisting of amylase, glutathione-S-transferase, alanine transaminase, aspartate transaminase, and combinations thereof.P5. The method of any one of potential claims Pl to P3, wherein the enzyme is amylase.P6. The method of any one of potential claims Pl to P5, wherein the inorganic catalyst is a metal.P7. The method of any one of potential claims P1-P6, wherein the inorganic catalyst is a metal selected from the group consisting of Fe, Mg, Cr, Ti, Mn, Au, Ag, Pt, and combinations thereof.P8. The method of any one of potential claims P6-P7, wherein the metal is prepared to have a high surface area.P9. The method of any one of potential claims P1-P8, wherein the inorganic catalyst is Pt.PIO. The method of any one of potential claims P1-P9, wherein the method is performed at a temperature between 1 and 99 degrees Celsius.P 11. A composition comprising an inorganic catalyst and a enzyme, the composition having efficacy for removing organofluorine compounds from water.Pl 2. The composition according to potential claim Pl 1, wherein the enzyme is amylase.P13. The composition according to potential claim Pl 1, wherein the enzyme is selected from the group consisting of amylase, glutathione-S-transferase, alanine transaminase, aspartate transaminase, and combinations thereof.P14. The composition of any one of potential claims Pl 1-P13, wherein the organofluorine compounds include compounds selected from the group consisting of perfluoroalkyl substances, polyfluoroalkyl substances, and combinations thereof.P15. The composition of any one of potential claims Pl 1-P14, wherein the inorganic catalyst is a metal selected from the group consisting of Fe, Mg, Cr, Ti, Mn, Au, Ag, Pt, and combinations thereof.P16. The composition of any one of potential claims Pl 1-P15, wherein the inorganic catalyst is Pt.Pl 7. A system for removing organofluorine compounds from a stream of water, the system comprising: a water supply feed configured to provide the stream of water; an injection device, downstream of the feed water supply mechanism, configured to deliver enzyme into the stream of water; a catalytic reactor, having an inorganic catalyst disposed therein, downstream of the injection device, configured to receive the stream of water so that the stream of water mixes with the inorganic catalyst; an ultrafiltration device, configured to receive an output of the catalytic reactor, having an ultrafiltration membrane, the ultrafiltration membrane configured to separate the enzyme andany organofluorine compounds bound to the enzyme from the water stream, so as to produce (i) a permeate stream in which the organofluorine compounds arc reduced at least 50 wt% compared to the amount present in the stream of water, and (ii) a retentate stream comprising free enzyme and enzyme bound to the organofluorine compounds; and a purge control valve configured to (i) recirculate a first portion of the retentate stream into the stream of water, upstream of the catalytic reactor, and (ii) divert a second portion of the retentate stream as byproduct to a waste vessel.Pl 8. The system of potential claim Pl 7, wherein the organofluorine compounds include polyfluoroalkyl substances.Pl 9. The system of potential claim Pl 7, wherein the organofluorine compounds include perfluoroalkyl substances.P20. The system of any one of potential claims P17-P19, wherein the enzyme is selected from the group consisting of amylase, glutathione-S-transferase, alanine transaminase, aspartate transaminase, and combinations thereof.P21. The system of any one of potential claims P17-P19, wherein the enzyme is amylase.P22. The system of any one of potential claims P17-P21, wherein the inorganic catalyst is a metal.P23. The system of any one of potential claims 17-22, wherein the inorganic catalyst is provided on a scaffold within the catalytic reactor.P24. The system of any one of potential claims P17-P23, wherein the inorganic catalyst is a metal selected from the group consisting of Fe, Mg, Cr, Ti, Mn, Au, Ag, Pt, and combinations thereof.P25. The system of any one of potential claims P22-P24, wherein the metal is prepared to have a high surface area.P26. The system of any one of potential claims P17-P25, wherein the inorganic catalyst is Pt.

[0018] The publications (including patent publications), web sites, company names, books, manuals, treatise, and scientific literature referred to herein establish the knowledge that is available to those with skill in the art and are hereby incorporated by reference in their entirety to the same extent as if each was specifically and individually indicated to be incorporated by reference. Any conflict between any reference cited herein and the specific teachings of this specification shall be resolved in favor of the latter.

[0019] The embodiments of the disclosure described above are intended to be merely exemplary; numerous variations and modifications will be apparent to those skilled in the art.

Claims

What is claimed is:

1. A method of removing organo fluorine compounds from contaminated water, the method comprising: a) mixing the contaminated water with an enzyme; b) passing the mixture through a catalytic reactor, the catalytic reactor comprising a scaffold comprising an inorganic catalyst selected from the group consisting of a metal, a metal cation, an organometallic compound, and combinations thereof; c) filtering the mixture passed through the catalytic reactor by ultrafiltration to obtain a permeate stream and a retentate stream, wherein the organofluorine compounds present in the permeate stream are reduced by at least 50 wt% compared to the amount present in the contaminated water; and d) recovering the enzyme from the retentate stream.

2. The method of claim 1 wherein the organofluorine compounds include polyfluoroalkyl substances.

3. The method of claim 1 wherein the organofluorine compounds include perfluoroalkyl substances.

4. The method of claim 1, wherein the enzyme is selected from the group consisting of amylase, glutathione-S-transferase, alanine transaminase, aspartate transaminase, and combinations thereof.

5. The method of claim 1, wherein the enzyme is amylase.

6. The method of claim 1, wherein the inorganic catalyst is a metal.

7. The method of claim 1, wherein the inorganic catalyst is a metal selected from the group consisting of Fe, Mg, Cr, Ti, Mn, Au, Ag, Pt, and combinations thereof.

8. The method of claim 6, wherein the metal is prepared to have a high surface area.

9. The method of claim 1 , wherein the inorganic catalyst is Pt.

10. The method of claim 1, wherein the method is performed at a temperature between 1 and 99 degrees Celsius.

11. A composition comprising an inorganic catalyst and a enzyme, the composition having efficacy for removing organofluorine compounds from water.

12. The composition according to claim 11, wherein the enzyme is amylase.

13. The composition according to claim 11, wherein the enzyme is selected from the group consisting of amylase, glutathione-S-transferase, alanine transaminase, aspartate transaminase, and combinations thereof.

14. The composition of claim 1 1 , wherein the organofluorine compounds include compounds selected from the group consisting of perfluoroalkyl substances, polyfluoroalkyl substances, and combinations thereof.

15. The composition of claim 11, wherein the inorganic catalyst is a metal selected from the group consisting of Fe, Mg, Cr, Ti, Mn, Au, Ag, Pt, and combinations thereof.

16. The composition of claim 11, wherein the inorganic catalyst is Pt.

17. A system for removing organofluorine compounds from a stream of water, the system comprising: a water supply feed configured to provide the stream of water; an injection device, downstream of the feed water supply mechanism, configured to deliver enzyme into the stream of water; a catalytic reactor, having an inorganic catalyst disposed therein, downstream of the injection device, configured to receive the stream of water so that the stream of water mixes with the inorganic catalyst; an ultrafiltration device, configured to receive an output of the catalytic reactor, having an ultrafiltration membrane, the ultrafiltration membrane configured to separate the enzyme andany organofluorine compounds bound to the enzyme from the water stream, so as to produce (i) a permeate stream in which the organofluorine compounds arc reduced at least 50 wt% compared to the amount present in the stream of water, and (ii) a retentate stream comprising free enzyme and enzyme bound to the organofluorine compounds; and a purge control valve configured to (i) recirculate a first portion of the retentate stream into the stream of water, upstream of the catalytic reactor, and (ii) divert a second portion of the retentate stream as byproduct to a waste vessel.

18. The system of claim 17, wherein the organofluorine compounds include polyfluoroalkyl substances.

19. The system of claim 17, wherein the organofluorine compounds include perfluoroalkyl substances.

20. The system of claim 17, wherein the enzyme is selected from the group consisting of amylase, glutathione-S-transferase, alanine transaminase, aspartate transaminase, and combinations thereof.

21. The system of claim 17, wherein the enzyme is amylase.

22. The system of claim 17, wherein the inorganic catalyst is a metal.

23. The system of claim 17, wherein the inorganic catalyst is provided on a scaffold within the catalytic reactor.

24. The system of claim 17, wherein the inorganic catalyst is a metal selected from the group consisting of Fe, Mg, Cr, Ti, Mn, Au, Ag, Pt, and combinations thereof.

25. The system of claim 22, wherein the metal is prepared to have a high surface area.

26. The system of claim 17, wherein the inorganic catalyst is Pt.

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