Renewable systems for pollutant removal

Abstract

Described herein are systems and methods for water purification by capture of contaminants in an aqueous mixture. Also described are systems and methods for regenerating a capture system. Also described are integrated capture and regeneration systems and methods including a separation vessel housing a capture bed and, optionally, electrodes in electrical contact with the bed via a power source for applying a voltage to the electrodes. The aqueous wash solution may include counterions that bind to the contaminants to form a flocculated contaminant phase that separates from the aqueous wash solution. The capture bed may be treated with, for example, hydroxide and / or peroxide before the counterions bind to the contaminants.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Application No. 63 / 290,231, filed December 16, 2021, the disclosure of which is incorporated herein by reference in its entirety.

[0002] The present invention relates to a system and method for removing ionic contaminants from an aqueous mixture using a capture bed and for regenerating the capture bed for subsequent use. [Background technology]

[0003] This section provides background information related to the present disclosure and is not necessarily prior art.

[0004] Water purification technologies are of fundamental importance to everyday life. Before water can be used for drinking or other purposes, it must be purified to an acceptable level by removing contaminants. Per- and polyfluoroalkyl substances (PFAS) are of particular concern and are particularly important to remove from water. Existing technologies for water purification through removal of contaminants, including PFAS, have issues with efficiency and environmental sustainability. For example, technologies that capture contaminants such as PFAS with ion exchange resins or carbon beds currently require replacement of the beds and disposal of used beds in landfills.

[0005] Thus, although technology already exists to remove contaminants such as PFAS (and other similar polyfluorinated hydrocarbons) from water, there remains a need for improved technologies that provide more effective removal of contaminants and are renewable for continued use without requiring expensive and inefficient replacement and environmentally harmful disposal of system components. Summary of the Invention [Means for solving the problem]

[0006] In one aspect, disclosed herein is a method for removing contaminants from an aqueous mixture. The method includes flowing a contaminated aqueous mixture containing one or more ionic contaminants into a vessel containing a carbon bed, where the one or more ionic contaminants are retained by the carbon bed. The method includes converting the one or more ionic contaminants retained by the carbon bed into (a) hydroxides and / or peroxides, and (b) Ca 2+ , Mg 2+ , Zn 2+ , Sr 2+ , Al 3+ , B 3+ , and Fe 3+ (a) hydroxide and / or peroxide, and (b) the one or more cations are provided in a single aqueous liquid or two or more separate aqueous liquids for contacting the one or more ionic contaminants. The method further includes forming a flocculated contaminant phase comprising the one or more ionic contaminants, and isolating the flocculated contaminant phase.

[0007] In some embodiments, the aggregated contaminant phase is formed by precipitation, micelle formation, aggregation, flocculation, flotation, or emulsion breaking. In some embodiments, the (a) hydroxide and / or peroxide comprises sodium hydroxide. In other embodiments, the (a) hydroxide and / or peroxide comprises hydrogen peroxide. Also, in some embodiments, the (a) hydroxide and / or peroxide comprises sodium peroxide.

[0008] In some embodiments, (b) the one or more cations are Ca 2+ For example, Ca 2+ is provided as calcium hydroxide. In another embodiment, (b) the one or more cations are Al 3+ For example, Al 3+ is provided as aluminum sulfate, aluminum hydroxide, or sodium aluminate.

[0009] In some embodiments, (a) the hydroxide and / or peroxide are provided in a first aqueous liquid and (b) the one or more cations are provided in a second aqueous liquid, hi some embodiments, the first aqueous liquid is contacted with the one or more ionic contaminants prior to the second aqueous liquid.

[0010] In another aspect, disclosed herein is a method for removing contaminants from an aqueous mixture, the method including: flowing a contaminated aqueous mixture including one or more ionic contaminants into a vessel containing a carbon bed, where the one or more ionic contaminants are retained by the carbon bed; contacting the one or more ionic contaminants retained by the carbon bed with (a) sodium hydroxide and / or hydrogen peroxide, and (b) calcium hydroxide, aluminum hydroxide, and / or aluminum sulfate, where the (a) sodium hydroxide and / or hydrogen peroxide, and (b) calcium hydroxide, aluminum hydroxide, and / or aluminum sulfate are provided in a single aqueous liquid or two or more separate aqueous liquids for contacting the one or more ionic contaminants; forming a flocculated contaminant phase including the one or more ionic contaminants; and isolating the flocculated contaminant phase.

[0011] In some embodiments, (a) sodium hydroxide and / or hydrogen peroxide are provided in a first aqueous liquid for contacting the one or more ionic contaminants, and (b) calcium hydroxide, aluminum hydroxide, and / or aluminum sulfate are provided in a second aqueous liquid for contacting the one or more ionic contaminants. In some embodiments, the first aqueous liquid is contacted with the ionic contaminants before the second aqueous liquid.

[0012] In some embodiments, the methods further include rinsing the carbon bed with an aqueous acid solution by flowing the aqueous acid solution through the vessel. In some embodiments, the aqueous acid solution includes hydrochloric acid, citric acid, sulfuric acid, nitric acid, or any combination thereof. For example, the aqueous acid solution can include hydrochloric acid. Also, in some embodiments, the aqueous acid solution includes an acid salt.

[0013] In some embodiments, the methods further include rinsing the carbon bed with water by running the water through the vessel. In some embodiments, the water is substantially free of additives.

[0014] In some embodiments, these methods further include repeating the steps of (i) contacting the ionic contaminants with (a) hydroxide and / or peroxide, (ii) contacting the ionic contaminants with (b) one or more cations, (iii) rinsing with an aqueous acidic solution, and (iv) rinsing with water one or more times.

[0015] In some embodiments, these methods include treating the carbon bed with (a) hydroxide and / or peroxide, and (b) Ca prior to flowing the contaminated aqueous mixture into the vessel. 2+ , Mg 2+ , Zn 2+ , Sr 2+ , Al 3+ , B 3+ , and Fe 3+ In some embodiments, the pretreatment further comprises rinsing the carbon bed with an acidic aqueous solution and rinsing the carbon bed with water.

[0016] In some embodiments, the ionic contaminant comprises an organic end with an ionic moiety. For example, the ionic contaminant is selected from the group consisting of polyfluoroalkyl ions, borates, phosphates, polyphosphates, sulfates, organic acids, fatty acids, humic substances, short chain PFAS, water-soluble pharmaceuticals, detergents, water-soluble insecticides, water-soluble fungicides, water-soluble bactericides, and any combination thereof. In some embodiments, the ionic contaminant is a polyfluoroalkyl ion. Also, in some embodiments, the polyfluoroalkyl ion is perfluorooctane sulfonate or perfluorooctanoate.

[0017] In some embodiments, the carbon bed comprises a powder, granules, beads, pellets, fabric, felt, non-woven fabric, or composite comprising a material selected from carbon, nitrogen-doped carbon, silicon-doped carbon, boron-doped carbon, charcoal, graphite, biochar, coke, carbon black, or any combination thereof. In some embodiments, the carbon bed comprises activated charcoal powder, granules, pellets, beads, or any combination thereof. In some embodiments, the vessel is a pipe, column, or tank. In other embodiments, isolating the aggregated contaminant phase comprises filtration, nanofiltration, or sedimentation.

[0018] In some embodiments, the methods further include contacting one or more ionic contaminants with a surfactant. In some embodiments, the surfactant is selected from a fatty acid, a sulfone, a phosphate, a polyether, a sulfate, a polyol, or any combination thereof. Also, in some embodiments, the surfactant is selected from sodium dodecyl sulfate (SDS), sorbitan monolaurate, polyethylene glycol (PEG), or any combination thereof.

[0019] In some embodiments, the surfactant is contacted with the one or more ionic contaminants before (a) the hydroxides and / or peroxides are contacted with the one or more ionic contaminants. In other embodiments, the surfactant is contacted with the one or more ionic contaminants after (a) the hydroxides and / or peroxides are contacted with the one or more ionic contaminants. Also, in some embodiments, the surfactant is contacted with the one or more ionic contaminants simultaneously with (a) the hydroxides and / or peroxides.

[0020] In some embodiments, the methods further include contacting the one or more ionic contaminants with a flocculant. In some embodiments, the flocculant includes an oil, a terpene, a fatty acid ester, or any combination thereof. Also, in some embodiments, the flocculant is selected from safflower oil, rapeseed oil, limonene, ethyl octanoate, or any combination thereof.

[0021] In some embodiments, the flocculant contacts the one or more ionic contaminants before (a) the hydroxides and / or peroxides contact the one or more ionic contaminants. In other embodiments, the flocculant contacts the one or more ionic contaminants after (a) the hydroxides and / or peroxides contact the one or more ionic contaminants. Also, in some embodiments, the flocculant contacts the one or more ionic contaminants simultaneously with (a) the hydroxides and / or peroxides.

[0022] In some embodiments, the carbon bed is an activated carbon bed, and in some embodiments, the carbon bed comprises sintered carbon.

[0023] In another aspect, disclosed herein is a method of regenerating a carbon bed, the method comprising providing a vessel for containing a carbon bed having one or more ionic contaminants retained thereon or therein, and treating the one or more ionic contaminants retained by the carbon bed with (a) hydroxides and / or peroxides, and (b) Ca. 2+ , Mg 2+ , Zn 2+, Sr 2+ , Al 3+ , B 3+ , and Fe 3+ wherein the one or more cations are provided in a single aqueous liquid or two or more separate aqueous liquids for contacting the one or more ionic contaminants, forming a flocculated contaminant phase comprising the one or more ionic contaminants, and isolating the flocculated contaminant phase.

[0024] In a further aspect, disclosed herein is a method for removing contaminants from an aqueous mixture. The method includes flowing a contaminated aqueous mixture containing one or more ionic contaminants into a vessel containing a carbon bed, where the one or more ionic contaminants are retained by the carbon bed. The method also includes converting the one or more ionic contaminants retained by the carbon bed into (a) hydroxides and / or peroxides, and (b) Ca. 2+ , Mg 2+ , Zn 2+ , Sr 2+ , Al 3+ , B 3+ , and Fe 3+ The method includes contacting the one or more ionic contaminants retained by the carbon bed with one or more cations selected from: (a) hydroxide and / or peroxide, and (b) the one or more cations are provided in a single aqueous liquid or two or more separate aqueous liquids for contacting the one or more ionic contaminants. The method further includes contacting the one or more ionic contaminants retained by the carbon bed with a flocculant. The method also further includes forming a flocculant phase comprising the one or more ionic contaminants and isolating the flocculant phase.

[0025] In some embodiments, the flocculant comprises an oil, a terpene, a fatty acid ester, or any combination thereof. For example, the flocculant may comprise an oil, and the oil is selected from coconut oil, corn oil, cottonseed oil, olive oil, palm oil, peanut oil, rapeseed oil, safflower oil, sesame oil, soybean oil, sunflower oil, or any combination thereof. In some embodiments, the flocculant comprises a terpene, and the terpene is selected from myrcene, menthol, limonene, carvone, hinokitiol, linalool, or any combination thereof. In some embodiments, the flocculant comprises a fatty acid ester, and the fatty acid ester is ethyl octanoate. Also, in some embodiments, the flocculant is selected from safflower oil, rapeseed oil, limonene, ethyl octanoate, or any combination thereof.

[0026] In some embodiments, the method further comprises contacting one or more ionic contaminants with a surfactant. For example, the surfactant may be selected from a fatty acid, a sulfone, a phosphate, a polyether, a sulfate, a polyol, or any combination thereof. Also, in some embodiments, the surfactant is selected from sodium dodecyl sulfate (SDS), polyethylene glycol (PEG), or any combination thereof.

[0027] In some embodiments, the method further comprises contacting the one or more ionic contaminants with an antifreeze agent. In some embodiments, the antifreeze agent is selected from the group consisting of propylene glycol, polypropylene glycol, polyethylene glycol, glycerol, polyvinyl alcohol, carboxymethyl cellulose, ribose, sucrose, glucose, rhamnose, xylose, fructose, raffinose, stachyose, low molecular weight hydroxyethyl starch, maltodextrin, cellodextrin, and combinations thereof. Also, in some embodiments, the antifreeze agent comprises glycerol.

[0028] In some embodiments, the method further comprises rinsing the carbon bed with an aqueous acid solution by flowing the aqueous acid solution through the vessel. In some embodiments, the aqueous acid solution comprises hydrochloric acid, citric acid, sulfuric acid, nitric acid, or any combination thereof. Also, in some embodiments, the aqueous acid solution comprises an acid salt.

[0029] In some embodiments, (a) hydroxide and / or peroxide are provided in a first aqueous liquid for contacting one or more ionic contaminants, and (b) one or more cations are provided in a second aqueous liquid for contacting one or more ionic contaminants. In some embodiments, the second aqueous liquid further comprises a surfactant and an antifreeze agent. In other embodiments, the second aqueous liquid further comprises a surfactant, an antifreeze agent, and a flocculant. In some embodiments, the first aqueous liquid contacts one or more ionic contaminants before the second aqueous liquid. Also, in some embodiments, the flocculant is provided as a layer of flocculant downstream of the vessel.

[0030] In another aspect, disclosed herein is a method for removing contaminants from an aqueous mixture. The method includes flowing a contaminated aqueous mixture containing one or more ionic contaminants into a vessel containing a carbon bed, where the one or more ionic contaminants are retained by the carbon bed. The method also includes converting the one or more ionic contaminants retained by the carbon bed into (a) hydroxides and / or peroxides, and (b) Ca 2+ , Mg 2+ , Zn 2+ , Sr 2+ , Al 3+ , B 3+ , and Fe 3+The method further comprises contacting the one or more ionic contaminants retained by the carbon bed with one or more cations selected from: (a) hydroxide and / or peroxide, and (b) one or more cations, provided in a single aqueous liquid or two or more separate aqueous liquids for contacting the one or more ionic contaminants. The method further comprises contacting the single aqueous liquid or the two or more separate aqueous liquids with a flocculant to form a flocculant phase comprising the one or more ionic contaminants. The method also further comprises isolating the flocculant phase.

[0031] Other features and advantages of the invention will become apparent from the following detailed description, the drawings, and the claims.

[0032] The following figures are provided as examples and are not intended to limit the scope of the claimed invention. [Brief description of the drawings]

[0033] [Figure 1] FIG. 1 is a diagram of a capture system for removing contaminants from water, according to one embodiment of the present invention.

[0034] [Diagram 2] 1A and 1B are schematic diagrams of a capture system (A) and a regeneration system (B) according to another embodiment of the present invention.

[0035] [Figure 3A] FIG. 11 is a process diagram of an integrated capture and playback system according to another embodiment of the present invention. [Figure 3B] FIG. 11 is a process diagram of an integrated capture and playback system according to another embodiment of the present invention.

[0036] [Figure 4] 1 is a flowchart showing steps of a first embodiment.

[0037] [Diagram 5] 1 shows the appearance of the carbon substrate of Example 1.

[0038] [Figure 6] 1 is a chart showing the absorption of PFNA from a mixed contaminant sample by a fresh carbon bed.

[0039] [Figure 7] 1 is a chart showing the absorption of PFNAs from mixed contaminant samples by regenerated carbon beds.

[0040] [Figure 8] 1 is a chart showing the absorption of PFOA from mixed contaminant samples by a fresh carbon bed.

[0041] [Figure 9] 1 is a chart showing the absorption of PFOA from mixed contaminant samples by regenerated carbon beds.

[0042] [Figure 10] 1 is a chart showing the absorption of PFOS from mixed contaminant samples by a fresh carbon bed.

[0043] [Figure 11] 1 is a chart showing the absorption of PFOS from mixed contaminant samples by regenerated carbon beds.

[0044] [Figure 12] 1 is a chart showing the concentration of PFOA in the filtrate collected after running through a carbon bed in a column.

[0045] [Figure 13] 1 is a plot showing PFOA concentration in effluent for fresh and used GAC according to Example 7.

[0046] [Figure 14]1 is a plot showing PFOA concentration in effluent for pretreated and non-pretreated GAC according to Example 7.

[0047] [Figure 15] 1 is a chart showing adsorption isotherms. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0048] I. Definition

[0049] The terms used herein are for the purpose of describing particular example configurations only and are not intended to be limiting. As used herein, the singular articles "a," "an," and "the" may be intended to include the plural unless the context clearly dictates otherwise. The terms "comprises," "comprising," "including," and "having" are inclusive and thus specify the presence of features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof. The method steps, processes, and operations described herein should not be construed as necessarily requiring their execution in the particular order described or illustrated, unless specifically identified as an order of execution. Additional or alternative steps may be employed.

[0050] In this specification, terms such as first, second, third, etc. may be used to describe various elements, components, regions, layers, and / or sections. These elements, components, regions, layers, and / or sections should not be limited by these terms. These terms may only be used to distinguish one element, component, region, layer, or section from another region, layer, or section. Terms such as "first", "second", and other numerical terms do not imply an arrangement or order unless clearly indicated by the context. Thus, a first element, component, region, layer, or section described below may be referred to as a second element, component, region, layer, or section without departing from the teachings of the exemplary configuration.

[0051] Terms such as above, below, top, bottom, right, left, etc. may be used herein to describe the location of various elements relative to other elements. These terms represent the location of elements in an exemplary configuration. However, as would be apparent to one of ordinary skill in the art, elements can be spatially rotated without departing from the present disclosure, and therefore these terms should not be used to limit the scope of the present disclosure.

[0052] As used herein, when an element is "adjacent," "engaged," "connected," "attached," or "coupled" to another element, it may be directly adjacent, engaged, connected, attached, or coupled to the other element, or there may be intervening elements. In contrast, when an element is "directly adjacent," "directly engaged," "directly connected," "directly attached," or "directly coupled" to another element, there may be no intervening elements or layers. Other words used to describe relationships between elements should be interpreted similarly (e.g., "between" and "directly between," "adjacent" and "directly adjacent," etc.). As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0053] As used herein, the term "electrode" refers to a solid electrical conductor that carries electrical current to another element, such as a capture bed.

[0054] As used herein, the term "activated carbon" refers to a form of carbon that has been processed to have small pores that increase its available surface area.

[0055] As used herein, "polyfluoroalkyl ion" refers to an ionic compound containing an alkyl chain having multiple fluoro substitutions and optionally further substituted with ethers, alcohols, amines (including substituted amines), carboxylic acid groups, and the like.

[0056] "Perfluoroalkyl and polyfluoroalkyl substances" or "PFAS" includes, but is not limited to, the following substances: perfluorobutanoic acid, perfluoropentanoic acid, perfluorohexanoic acid (PFHxA), perfluoroheptanoic acid (PFHpA), perfluorooctanoic acid, perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluoroundecanoic acid (PFUnA), perfluorododecanoic acid (PFDoA), perfluorotridecanoic acid, perfluorotetradecanoic acid, perfluorohexadecanoic acid, perfluorooctadecanoic acid, perfluorobutanesulfonic acid, perfluoropentanesulfonic acid, perfluorohexanesulfonic acid (PFHxS), perfluorooctanesulfonic acid, perfluorononanesulfonic acid, perfluorodecanesulfonic acid, perfluorododecanesulfonic acid, perfluorooctanesulfonamide, and N-methylperfluoro-1-octanesulfonamide. perfluorohexanesulfonic acid (4:2), 1H,1H,2H,2H-perfluorooctanesulfonic acid (6:2), 1H,1H,2H,2H-perfluorodecanesulfonic acid (8:2), 1H,1H,2H,2H-perfluorododecanesulfonic acid (10:2), N-methylperfluorooctanesulfonamideacetic acid, N-ethylperfluorooctanesulfonamide Amidoacetic acid, 2-(N-methylperfluoro-1-octanesulfonamido)-ethanol, 2-(N-ethylperfluoro-1-octanesulfonamido)-ethanol, tetrafluoro-2-(heptafluoropropoxy)propanoic acid ("GenX"), 4,8-dioxa-3H-perfluorononanoic acid, 11-chloroeicosafluoro-3-oxaundecane-1-sulfonic acid, or 9-chlorohexadecafluoro-2-oxanone-1-sulfonic acid. PFAS also include partially fluorinated acids. The conjugate bases of these acids are examples of polyfluoroalkyl ions. Trapping PFAS includes trapping the conjugate bases of the PFAS.

[0057] "PFOS" refers to perfluorooctanesulfonic acid. Capture / release of PFOS includes capture / release of its conjugate base, perfluorooctanesulfonate.

[0058] "PFOA" refers to perfluorooctanoic acid. Capture / release of PFOA includes capture / release of its conjugate base, perfluorooctanoate.

[0059] Systems and methods are described herein. It will be understood that embodiments of the invention described with reference to a system may be applicable to the methods described herein, and vice versa. For example, from a description of a particular carbon bed, such as an activated carbon bed, in a system, it will be understood that the activated carbon bed may be used in the method. Similarly, as another example, from a description of the application of a particular voltage in a method, it will be understood that the system may be configured to apply the particular voltage.

[0060] II. System for Regenerating Capture Beds

[0061] In one aspect, provided herein is a system for regenerating a trapping bed, i.e., a "regeneration system." Regeneration refers to the removal of ionic contaminants from the trapping bed (i.e., contaminants bound to the trapping bed during the water purification process). Described herein are systems and methods for removing ionic contaminants from an aqueous mixture by trapping the ionic contaminants in the trapping bed. As more ionic contaminants bind to the trapping bed, the bed becomes less effective at removing the ionic contaminants. Eventually, the contaminants must be liberated from the trapping bed or the trapping bed itself must be replaced. Regenerating the trapping bed in situ by liberating the bound ionic contaminants allows for continued use of the trapping bed without the costly replacement and environmentally harmful disposal of the used trapping bed.

[0062] The system for regenerating a trapping bed includes a trapping bed contained within a separation vessel. The system may optionally be an electrification system comprising an electrode in electrical contact with the trapping bed contained within the separation vessel; a power source electrically coupled to the electrode and configured to apply a voltage to the electrode; and a controller configured to control and regulate the voltage applied to the electrode from the power source. By allowing a voltage to be applied to the electrode in electrical communication with the trapping bed, the regeneration system can apply a voltage to the trapping bed that drives the release of ionic contaminants from the trapping bed.

[0063] In some embodiments, the electrodes comprise graphite, titanium, stainless steel, cast iron, conductive metal oxides, conductive diamond, titanium suboxide, titanium nitride, titanium carbide, titanium boride, doped manganese oxide, or mixtures or composites thereof.

[0064] The system for regenerating the trapping bed also includes a regeneration line fluidly connected to the separation vessel and configured to introduce a flow of an aqueous wash solution into the separation vessel to wash ionic contaminants from the trapping bed. Applying a voltage to the electrodes and flowing the wash solution through the regeneration line and through the trapping bed drives the liberation of ionic contaminants from the trapping bed, thereby regenerating the trapping bed for subsequent use. In some embodiments, the regeneration line is fluidly connected to a regeneration line pump and / or a regeneration line valve to control the flow rate of the wash solution provided to the separation vessel. In some embodiments, the regeneration system includes a flow controller (e.g., a PLC controller) for controlling the regeneration line pump and / or the regeneration line valve.

[0065] In some embodiments, the regeneration system is a subsystem of an integrated capture and regeneration system. Such integrated systems are described below. The integrated system can be installed on-site as a stand-alone system to provide purified water. Alternatively, the regeneration system can be an add-on system to an existing capture system. For example, there may be an existing water purification system with a capture bed, such as a carbon bed or an ion exchange resin bed, and the regeneration system described herein may be installed as an add-on system to regenerate the existing water purification system in-situ. In some embodiments, the regeneration system allows for the continued use of the capture bed in the existing system by liberating, sequestering, and removing ionic contaminants in the capture bed.

[0066] In the following embodiment, an example of outfitting an existing capture system with an electrified regeneration system is described. To apply a voltage to the existing capture system, electrodes are equipped by insertion into the existing capture bed and connected to a power source controlled by a controller. A regeneration line is attached to the existing piping of the capture system (or directly to the separation vessel) so that inlet and outlet flows of wash fluid to the separation vessel are added separately. Valves, such as control valves, are equipped to control the flow rate to the separation vessel and to switch the flow source between (1) the aqueous mixture to be purified (during the capture cycle) and (2) the wash fluid to regenerate the capture bed.

[0067] In some embodiments, the regeneration system involves the concentration and removal of ionic contaminants liberated from the capture bed. In some embodiments, a contaminant sequestration agent is used that can be removed from the system more efficiently than removal of the capture bed. In some embodiments, disposal of the sequestration agent is more environmentally friendly than disposal of spent carbon beds or spent ion exchange resin beds (i.e., with bound contaminants).

[0068] In some embodiments, the sequestration agent is a counterion in the cleaning solution configured to bind to the ionic contaminants to form a flocculated contaminant phase. Suitable sequestration agents and counterions are described below. In some embodiments, the system further comprises a filter configured to remove the flocculated contaminant phase from the cleaning solution. Because the flocculated contaminant phase is poorly to insoluble in the aqueous phase, the precipitate tends to form a distinct solid or liquid phase large enough to float or sink, or large enough to be captured in a particulate filter. In some embodiments, a skimmer can be used to capture the flocculated contaminant phase.

[0069] In some embodiments, the regeneration system further includes a regeneration vessel that stores a fixed ion source configured to bind one or more ionic contaminants in the aqueous cleaning solution, the regeneration vessel being fluidly connected to the separation vessel. In some embodiments, the fixed ion source includes lime, e.g., a plurality of hydrated lime pellets. In some embodiments, the fixed ion source is an alkali metal-coated surface that reversibly holds the alkali element electrostatically or by dispersive forces until the contaminants can form a precipitate. The contaminants are held on the surface until the surface binding is reversed (e.g., the polarity of the electrodes is reversed).

[0070] In some embodiments, the regeneration system further comprises a sequestration agent container containing the sequestration agent in a liquid medium. In some embodiments, the regeneration system further comprises a mixing tank for mixing the sequestration agent with the washing liquid, and optionally a settling device for collecting solids that have settled from the liquid in the mixing tank. In some embodiments, a filter is fluidly connected to the mixing tank for filtering solids from the mixing tank, such as solids that have not been separated in the settling device.

[0071] In some embodiments, the aqueous cleaning solution comprises an untreated contaminated aqueous mixture. In some embodiments, the aqueous cleaning solution comprises 1-5and alcohol. In some embodiments, the aqueous cleaning solution further comprises an antifreeze agent that lowers the freezing point of the aqueous cleaning solution. In some embodiments, the antifreeze agent is selected from the group consisting of propylene glycol, polypropylene glycol, polyethylene glycol, glycerol, polyvinyl alcohol, carboxymethyl cellulose, ribose, sucrose, glucose, rhamnose, xylose, fructose, raffinose, stachyose, low molecular weight hydroxyethyl starch, maltodextrin, cellodextrin, and combinations thereof. In some embodiments, the aqueous cleaning solution comprises about 0.01% to about 20% by weight of an antifreeze agent (e.g., about 1% to about 10% by weight of an antifreeze agent, or about 0.01% to about 10% by weight of an antifreeze agent). In some embodiments, the freezing point of the aqueous cleaning solution is less than about -0.3°C. In some embodiments, the antifreeze agent promotes slush formation of the aqueous cleaning solution at freezing temperatures.

[0072] In some embodiments, the aqueous cleaning solution further comprises one or more additives for removing scale and / or inorganic precipitates from the capture bed. The inorganic precipitates may comprise, for example, iron or manganese. In some embodiments, the one or more additives are selected from the group consisting of acetic acid, propanoic acid, octanoic acid, glycolic acid, citric acid, ethylenediaminetetraacetic acid (EDTA), water-soluble fatty acids, salts of the foregoing acids (e.g., sodium or potassium salts), and mixtures of any thereof. In some embodiments, the acid is configured to solubilize inorganic precipitates or scale in the capture bed, for example, at or near the tip of the capture bed. In some embodiments, the pH of the aqueous cleaning solution including the additive(s) is about 0 to about 6. In some embodiments, the pH of the aqueous cleaning solution including the additive(s) is about 3 to about 6. In some embodiments, the concentration of the additive(s) in the aqueous cleaning solution is about 0.01% to about 15% by weight, or up to the solubility limit of the acid in the cleaning solution.

[0073] In some embodiments, the system further includes a second cleaning liquid that may be used to rinse the capture bed before, after, or simultaneously with the aqueous cleaning liquid. The second cleaning liquid may be referred to as a "rinsing liquid." The rinsing liquid may be introduced into the vessel via a rinsing liquid line. The rinsing liquid is an aqueous liquid that includes one or more additives for removing scale and / or inorganic precipitates from the capture bed. In some embodiments, the one or more additives are selected from the group consisting of acetic acid, propanoic acid, octanoic acid, glycolic acid, citric acid, ethylenediaminetetraacetic acid (EDTA), water-soluble fatty acids, salts of the foregoing acids (e.g., sodium or potassium salts), and mixtures of any thereof. In some embodiments, the pH of the rinsing liquid is about 3 to about 6. In some embodiments, the concentration of the additive(s) in the rinsing liquid is about 0.01% to about 15% by weight, or up to the solubility limit of the acid in the rinsing liquid.

[0074] FIG. 2 is a schematic diagram of an exemplary system 200 according to another embodiment of the present invention. FIG. 2A illustrates a capture system 200a, described in more detail below, that is being used to capture contaminants, specifically PFOA and / or PFOS, from a water source. FIG. 2B illustrates a regeneration system 200b. The regeneration system illustrated in FIG. 2B may be part of an integrated capture and regeneration system or may be an add-on regeneration system. A regeneration vessel 220 ("waste container") containing a wash solution is fluidly connected to a separation vessel 202 via a regeneration line 222, which contains a capture bed, specifically a capture bed stack 204 ("cell stack"), and is configured such that the wash solution flows to the separation vessel 202. A regeneration outlet line 224 is fluidly connected to the opposite end of the separation vessel. A valve 218b controls the flow rate out of the separation vessel via the regeneration outlet line 224. The regeneration outlet line 224 is fluidly connected to the regeneration vessel 220, thereby completing the circulation loop. The system 200b is configured to recirculate the cleaning solution through the separation vessel 202 multiple times, resulting in a cleaning solution with a high concentration of contaminants (e.g., PFOA / PFOS). The regeneration vessel 220 includes a fixed ion source 226, which as shown in this embodiment is hydrated lime pellets. The hydrated lime pellets 226 are configured to bind the PFOA / PFOS in the regeneration vessel 220. The hydrated lime pellets 226 can be easily removed from the system and disposed of. Disposal of the hydrated lime pellets is more economical and environmentally friendly than disposal of activated carbon beds or ion exchange resin beds.

[0075] III. Methods for Regenerating Capture Beds

[0076] Another aspect provided herein is a method for regenerating a capture bed, i.e., a "regeneration method." The method for regenerating a capture bed includes providing a container that contains a capture bed having one or more ionic contaminants bound thereto, and optionally, an electrode in electrical contact with the capture bed. The container can be part of an integrated capture and regeneration system that includes a system for capturing contaminants, as described below. Alternatively, the container can be part of an existing contaminant capture system (water purification system), where the regeneration method is performed on the existing container / capture system by fitting the regeneration system (as described above) to the existing container / capture system.

[0077] The method of regenerating the trapping bed further includes flowing an aqueous wash fluid through the vessel and, optionally, applying a voltage to the electrodes, whereby one or more ionic contaminants bound to the trapping bed are released from the trapping bed and washed from the bed via the aqueous wash fluid.

[0078] In some embodiments, an aqueous wash solution is passed into the separation vessel at a rate of about 5 to about 400 liters per minute per square meter of capture bed to dislodge the bound ionic contaminants from the capture bed and to wash the dislodged ionic contaminants from the capture bed.

[0079] In some embodiments, a voltage is applied to the electrodes. In some embodiments, a voltage having a positive polarity of about 0.01 V to about 1.5 V (e.g., about 0.01 V to about 1.2 V) is applied to the electrodes to drive the release of ionic contaminants from the capture bed and wash them away with a wash solution. In some embodiments, a voltage having a negative polarity of about -0.01 V to about -1.6 V is applied to the electrodes to drive the release of ionic contaminants. In some embodiments, an AC voltage, appropriately with a DC offset, is applied to drive the release of ionic contaminants. In some embodiments, no voltage is applied.

[0080] In some embodiments, the wash solution comprises a sequestration agent. In some embodiments, the sequestration agent is a counterion. In some embodiments, the counterion is Ca 2+ , Mg 2+ , Zn 2+ , Sr 2+ , Al 3+ , B 3+ , Al 3+ , or Fe 3+ The counterion is a cation selected from the group consisting of: 2+ In some embodiments, the counterion is Al 3+ In some embodiments, the counter ion is provided to the wash solution by the addition of calcium hydroxide, calcium oxide, or calcium chloride to the wash solution. In some embodiments, the wash solution is basic and contains Ca 2+ In some embodiments, the cleaning solution is acidic and the source of Ca 2+ The source is calcium chloride. In some embodiments, the counter ion is provided to the cleaning solution by the addition of aluminum hydroxide. In some embodiments, the counter ion is provided to the cleaning solution by the addition of a mixture of aluminum hydroxide and sodium hydroxide. In some embodiments, the counter ion is provided to the cleaning solution by the addition of NaAl(OH)4 (sodium aluminate).

[0081] In some embodiments, the cleaning solution or series of cleaning solutions comprises (a) hydroxide and / or peroxide, and (b) Ca 2+ , Mg 2+ , Zn 2+ , Sr 2+ , Al 3+ , B 3+ , and Fe 3+In some embodiments, the cleaning solution (or one or more of the cleaning solutions) comprises a hydroxide and / or a peroxide. In some embodiments, the hydroxide and / or peroxide comprises sodium hydroxide. In some embodiments, the hydroxide and / or peroxide comprises hydrogen peroxide. In some embodiments, the hydroxide and / or peroxide comprises sodium peroxide. In some embodiments, the cleaning solution (or one or more of the cleaning solutions) comprises one or more cations selected from Ca 2+ , Mg 2+ , Zn 2+ , Sr 2+ , Al 3+ , B 3+ , and Fe 3+ In some embodiments, the one or more cations are selected from Ca 2+ In some embodiments, Ca 2+ is provided as calcium hydroxide. In some embodiments, Ca 2+ is provided as calcium chloride. In some embodiments, the one or more cations are Al 3+ In some embodiments, Al 3+ is provided as aluminum sulfate. In some embodiments, Al 3+ is provided as sodium aluminate. In some embodiments, Al 3+ is provided as aluminum hydroxide (Al(OH)3). In some embodiments, aluminum hydroxide is used with sodium hydroxide. In some embodiments, (a) hydroxide and / or peroxide are provided in a first aqueous liquid and (b) one or more cations are provided in a second aqueous liquid. In some embodiments, the first aqueous liquid is contacted with one or more ionic contaminants prior to the second aqueous liquid. In other embodiments, the second aqueous liquid is contacted with one or more contaminants prior to the first aqueous liquid.

[0082] In some embodiments, the cleaning solution, or series of cleaning solutions, includes one or more of (a) sodium hydroxide and / or hydrogen peroxide, and (b) calcium hydroxide, aluminum hydroxide, and / or aluminum sulfate. In some embodiments, (a) sodium hydroxide and / or hydrogen peroxide are provided in a first aqueous liquid for contacting the one or more ionic contaminants, and (b) calcium hydroxide, aluminum hydroxide, and / or aluminum sulfate are provided in a second aqueous liquid for contacting the one or more ionic contaminants. In some embodiments, the first aqueous liquid contacts the ionic contaminants before the second aqueous liquid. In other embodiments, the second aqueous liquid contacts the one or more contaminants before the first aqueous liquid.

[0083] Without wishing to be bound by theory, it is believed that, among other possible advantages, (a) the hydroxides and / or peroxides facilitate the breakdown of biofilms on the carbon bed, which allows for efficient removal of ionic contaminants from the carbon bed.

[0084] In some embodiments, the cleaning solution comprises a surfactant. The surfactant may be any surfactant described herein. In some embodiments, the cleaning solution comprises a flocculant. The flocculant may be any flocculant described herein.

[0085] When (a) hydroxide and / or peroxide are provided in the first aqueous liquid and (b) one or more cations are provided in the second aqueous liquid, the second aqueous liquid may further comprise a surfactant. In some embodiments, the second aqueous liquid further comprises an antifreeze agent. In some embodiments, the second aqueous liquid further comprises a surfactant and an antifreeze agent. Also, in some embodiments, the second aqueous liquid further comprises a surfactant, an antifreeze agent, and a flocculant. The surfactant, antifreeze agent, and flocculant may be any of the surfactants, antifreeze agents, and flocculants described herein.

[0086] In some embodiments, the method of regeneration further comprises rinsing the carbon bed with an acidic aqueous solution by flowing the solution through the vessel. In some embodiments, the acidic aqueous solution comprises hydrochloric acid, citric acid, sulfuric acid, nitric acid, or any combination thereof. For example, the acidic aqueous solution may comprise hydrochloric acid. In some embodiments, the acidic aqueous solution comprises sulfuric acid. In some embodiments, the acidic aqueous solution comprises an acid salt. For example, the acidic aqueous solution may comprise FeCl2, FeCl3, or a combination thereof.

[0087] In some embodiments, the method of regeneration further comprises rinsing the carbon bed with water by running the water through the vessel. In some embodiments, the rinse water is substantially free of additives. The acid rinse, in some embodiments, occurs after the rinse with the second aqueous liquid, and in some embodiments, occurs before the water rinse.

[0088] In some embodiments, the method of regeneration further comprises contacting one or more ionic contaminants with a surfactant. The surfactant may be an anionic surfactant, a cationic surfactant, an amphoteric surfactant, a nonionic surfactant, or any combination thereof. In some embodiments, the surfactant is selected from a fatty acid, a sulfone, or a phosphate. In some embodiments, the surfactant is selected from a fatty acid, a sulfone, a phosphate, a polyether, a sulfate, a polyol, or any combination thereof. For example, the surfactant may comprise a fatty acid. In some embodiments, the surfactant comprises a sulfone. In other embodiments, the surfactant comprises a phosphate. In some embodiments, the surfactant comprises a polyether. In some embodiments, the surfactant comprises a sulfate (e.g., sodium dodecyl sulfate (SDS)). Also, in some embodiments, the surfactant comprises a polyol.

[0089] Suitable polyethers include, by way of non-limiting example, polyethylene glycol (PEG), polypropylene glycol (PPG), polytetramethylene glycol (PTMG), or any combination thereof. In some embodiments, the polyether comprises PEG. The PEG may have an average molecular weight of less than about 1,000 g / mol, less than about 750 g / mol, less than about 600 g / mol, or less than about 550 g / mol. In some embodiments, the PEG is PEG500, PEG400, PEG300, or any combination thereof. For example, the PEG may be PEG300.

[0090] In some embodiments, the surfactant is selected from sodium dodecyl sulfate (SDS), sorbitan monolaurate, PEG, or any combination thereof.

[0091] In some embodiments, the surfactant contacts the one or more ionic contaminants before the hydroxide and / or peroxide contacts the contaminants. In other embodiments, the surfactant contacts the one or more ionic contaminants after the hydroxide and / or peroxide contacts the contaminants. Also, in some embodiments, the surfactant contacts the one or more ionic contaminants simultaneously with the hydroxide and / or peroxide (e.g., the cleaning solution includes a surfactant and a hydroxide and / or peroxide).

[0092] In some embodiments, the surfactant contacts the one or more ionic contaminants before (a) the hydroxide and / or peroxide, and / or (b) one or more cations contact the contaminants. In other embodiments, the surfactant contacts the one or more ionic contaminants after (a) the hydroxide and / or peroxide, and / or (b) one or more cations contact the contaminants. Also, in some embodiments, the surfactant contacts the one or more ionic contaminants simultaneously with (a) the hydroxide and / or peroxide, and / or (b) one or more cations (e.g., a single aqueous liquid or two or more aqueous liquids include a surfactant).

[0093] In some embodiments, the method of regeneration further comprises contacting the one or more ionic contaminants with a flocculant. The flocculant may be any of the flocculants described herein.

[0094] In some embodiments, the flocculant contacts the one or more ionic contaminants before the hydroxide and / or peroxide contacts the contaminants. In other embodiments, the flocculant contacts the one or more ionic contaminants after the hydroxide and / or peroxide contacts the contaminants. Also, in some embodiments, the flocculant contacts the one or more ionic contaminants simultaneously with the hydroxide and / or peroxide (e.g., the cleaning solution includes the flocculant and the hydroxide and / or peroxide).

[0095] In some embodiments, the flocculant contacts the one or more ionic contaminants before (a) the hydroxide and / or peroxide, and / or (b) one or more cations contact the contaminants. In other embodiments, the flocculant contacts the one or more ionic contaminants after (a) the hydroxide and / or peroxide, and / or (b) one or more cations contact the contaminants. Also, in some embodiments, the flocculant contacts the one or more ionic contaminants simultaneously with (a) the hydroxide and / or peroxide, and / or (b) one or more cations (e.g., a single aqueous liquid or two or more aqueous liquids include the flocculant).

[0096] The step of contacting / rinsing the bed with a cleaning solution or series of cleaning solutions may be repeated, for example, once, twice, or three or more times.

[0097] The step of contacting / rinsing the bed with a cleaning solution or series of cleaning solutions can also be used as a pretreatment, i.e., before using the bed to capture contaminants. Pretreatment can include contacting the carbon bed with sodium hydroxide and / or hydrogen peroxide. Additionally or alternatively, pretreatment can include contacting the bed with Ca 2+ , Mg2+ , Zn 2+ , Sr 2+ , Al 3+ , B 3+ , and Fe 3+ (e.g., in the form of calcium hydroxide, calcium chloride, aluminum sulfate, aluminum hydroxide, or sodium aluminate). Pretreatment may also include rinsing the bed with an acid rinse (e.g., HCl) and / or a water rinse. The various embodiments described with respect to regenerating a carbon bed as described herein may be used as a pretreatment of the carbon bed, i.e., by performing the same treatment(s) before the bed is used to capture pollutants.

[0098] Polyfluorinated compounds possess extremely hydrophobic moieties and are therefore not believed to adsorb to activated carbon by a conventional isothermal mechanism. They are believed to follow a nucleation, growth, and aggregation mechanism in which hydrophobic moieties aggregate together. These domains appear as micelles attached to the surface of activated carbon at high solution concentrations. To form, a few molecules of the perfluorinated compound first find an adsorption site on the activated carbon with some initial affinity. Subsequent perfluorinated compounds then preferentially adsorb to the previously adsorbed perfluorinated compounds. As the hydrophobic domains grow, the available surface area for adsorption increases until the micelles become too large to remain attached to the carbon surface. This adsorption mechanism results in adsorbed amount versus solution concentration curves that look like traditional Langmuir or Freundlich adsorption isotherms, but are different enough to be evident when fitting experimental data (Figure 15). The nucleation and growth model fits the experimental data better and better predicts macroscopic column behavior. Descriptions of these adsorption mechanisms are useful for predicting the exhaustion behavior of activated carbon beds or columns when treating natural water sources. There is confusion in the literature for these compounds because most researchers perform brute force fitting to isotherms / surface coverage mechanisms obtained over a small concentration range. However, nucleation and growth models provide a better fit and predict behavior over many orders of magnitude of concentration.

[0099] Without being bound by theory, it is believed that the addition of divalent and trivalent metal salts to PFAS solutions causes the stabilization of these micelles. This is because most perfluorinated compounds found in water also contain hydrophilic moieties that usually form insoluble salts with the perfluorinated compounds. The effect of these insoluble salts is to increase the effective hydrophobicity of the perfluorinated compounds and stabilize both free and surface micelle formation. The size of these stabilized micelles can reach tens of microns. These insoluble salts can also be generated by non-fluorinated compounds. These insoluble hydrophobic salts can also be used to stabilize the micelles of perfluorinated compounds. Once these micelles form on the carbon, other organic compounds can become adsorbed into these micellar domains. These insoluble salts of perfluorinated compounds, fatty acids, sulfonic acids, or phosphoric acids are useful for pretreating the carbon surface to provide stabilization of nucleation and micelle formation on the carbon surface. They may be applied to the micelles of the metal salts and the precipitated compounds together with the carbon, or they may be applied sequentially to the carbon. It does not matter whether the metal salt is applied first and then the compound, or the compound is applied first and then the metal salt. Pretreatment of the carbon in this manner can increase the adsorption capacity of the carbon by up to 70-fold (e.g., 2-10-fold) for perfluorinated compounds found in natural or industrial water sources. This pretreatment may also improve the adsorption kinetics, which may reduce treatment times.

[0100] In some embodiments, the pH of the aqueous wash solution is adjusted to precipitate the flocculated contaminant phase from the aqueous wash solution. For example, lime or other hydroxides can be added to the aqueous wash solution to change the pH. Sodium hydroxide, carbon dioxide, bicarbonate, phosphoric acid, and sulfuric acid can also be used as pH adjusters. In some embodiments, the pH is adjusted distal to (i.e., downstream of) the capture bed. pH adjustment can be achieved by lime washing the column by bubbling carbon dioxide or adding bicarbonate to a separate tank upstream of the capture bed. This reduces the pH of the Ca(OH)2 solution to a neutral or near-neutral pH, improving the flocculated size of the precipitate by co-precipitating calcium carbonate with the perfluoroalkyl compound. Alternatively, phosphoric acid and sulfuric acid can be introduced to form salts with calcium and act as neutralizing agents. In some embodiments, the wash solution includes sodium hydroxide.

[0101] In some embodiments, the counterion is an anion selected from phosphate, sulfate, or borate. The anion is suitable for use in regenerating a capture bed containing bound cationic contaminants, such as perfluoroalkyl cations. In some embodiments, the counterion is provided to the wash solution by adding calcium phosphate, calcium borate, calcium sulfate, magnesium phosphate, magnesium borate, or magnesium sulfate to the wash solution.

[0102] In some cases, the perfluoroalkyl compound may be non-ionic and must first be partially decomposed before it can be liberated by the use of a counterion. In such cases, the regeneration method further includes partially decomposing the non-ionic perfluoroalkyl compound(s), for example by chemical, photochemical, electrochemical decomposition, or by application of a DC or AC discharge.

[0103] In some embodiments, when the cleaning solution containing the sequestration agent is passed into a separation vessel, the sequestration agent and the liberated ionic contaminants form a flocculated contaminant phase. In some embodiments, the flocculated contaminant phase separates from the aqueous cleaning solution by precipitation. In other embodiments, the flocculated contaminant phase forms a foam. In other embodiments, the flocculated contaminant phase forms a dispersed phase in the aqueous cleaning solution. In other embodiments, the flocculated contaminant phase is formed by micelle formation, aggregation, flocculation, flotation, or emulsion breaking.

[0104] In some embodiments, the flocculated contaminant phase is isolated from the wash liquor, hi some embodiments, the isolation comprises filtration, nanofiltration, or sedimentation.

[0105] In some embodiments, the aqueous wash solution is at least substantially saturated with ionic contaminants when it leaves the capture bed.

[0106] In some embodiments, the regeneration method includes adding a sequestration agent to the cleaning solution. In some embodiments, a sequestration agent container is provided containing a sequestration agent in a liquid medium (e.g., an aqueous medium), and the sequestration agent flows from the sequestration agent container and is added to the cleaning solution. The flow rate may be controlled by a pump and / or a valve. In some embodiments, the sequestration agent is mixed with the cleaning solution, for example, in a mixing tank. In some embodiments, the cleaning solution mixed with the sequestration agent is a cleaning solution that is substantially saturated with ionic contaminants.

[0107] In some embodiments, a rinse solution containing the additive(s) described above is run through the vessel and capture bed. The rinse solution may be used before, after, or simultaneously with the aqueous cleaning solution. In some embodiments, the method further includes removing and optionally solubilizing inorganic precipitates or scale in the capture bed, for example at or near the top of the capture bed.

[0108] In some embodiments, the regeneration method further comprises contacting the liberated ionic contaminants in the aqueous cleaning solution with a fixed ion source such that the ionic contaminants bind to the fixed ion source to form an aggregated contaminant phase.

[0109] In some embodiments, the regeneration method further comprises contacting the aqueous wash liquor containing the ionic contaminants (e.g., the aqueous wash liquor after flowing to the separation vessel) with a flocculant. The flocculant, alone or in combination with a sequestration agent, facilitates and / or promotes the flocculation of the ionic contaminants. For example, the regeneration method may further comprise contacting the wash liquor containing the ionic contaminants with a flocculant to form a flocculant contaminant phase. In some embodiments, the flocculant contaminant phase separates from the aqueous wash liquor by precipitation. In other embodiments, the flocculant contaminant phase forms a foam. In other embodiments, the flocculant contaminant phase forms a dispersed phase in the aqueous wash liquor.

[0110] The flocculant may be any agent suitable for facilitating and / or promoting the flocculation of ionic contaminants, alone or in combination with a sequestrant. In some embodiments, the flocculant comprises an oil, a terpene, a fatty acid ester, or any combination thereof. For example, the oil may be selected from coconut oil, corn oil, cottonseed oil, olive oil, palm oil, peanut oil, rapeseed oil (e.g., canola oil), safflower oil, sesame oil, soybean oil, sunflower oil, or any combination thereof. In some embodiments, the oil comprises safflower oil, rapeseed oil, or any combination thereof. In some embodiments, the terpene is selected from myrcene, menthol, limonene, carvone, hinokitiol, linalool, or any combination thereof. In some embodiments, the fatty acid ester is ethyl octanoate. Also, in some embodiments, the flocculant is selected from safflower oil, rapeseed oil, limonene, ethyl octanoate, or any combination thereof.

[0111] In some embodiments, the regeneration method further comprises removing the flocculated contaminant phase. In some embodiments, removing the flocculated contaminant phase comprises filtering the flocculated contaminant phase from the cleaning solution.

[0112] In some embodiments, the regeneration method further comprises disposing of the removed aggregated contaminant phase, such as in a landfill. The aggregated contaminant phase may be destroyed, such as by calcination, pyrolysis, or vitrification. In some embodiments, the regeneration method further comprises electrochemical oxidation of the cleaning solution.

[0113] In some embodiments, the regeneration method further comprises pre-oxidizing the ionic contaminants, which comprises converting alcohol groups of the ionic contaminants to carboxylic acid groups by chemical or electrochemical means.

[0114] In some embodiments, the ionic contaminant comprises an organic end with an ionic moiety. In some embodiments, the ionic contaminant is selected from the group consisting of polyfluoroalkyl ions, borates, phosphates, polyphosphates, sulfates, organic acids, fatty acids, humic substances, short chain PFAS, water soluble pharmaceuticals, detergents, water soluble insecticides, water soluble fungicides, water soluble bactericides, and any combination thereof. In some embodiments, the ionic contaminant is a polyfluoroalkyl ion. In some embodiments, the polyfluoroalkyl ion is perfluorooctane sulfonate or perfluorooctanoate. Perfluorooctane sulfonate is the conjugate base of perfluorooctane sulfonic acid (PFOS). Perfluorooctanoate is the conjugate base of perfluorooctanoic acid (PFOA). In some embodiments, the polyfluoroalkyl ion is perfluorobutane sulfonate or perfluorobutanoate. Perfluorobutane sulfonate is the conjugate base of perfluorobutane sulfonic acid (PFBS). Perfluorobutanoate is the conjugate base of perfluorobutanoic acid (PFBA).

[0115] The system of FIG. 2B can also be described in terms of the regeneration method it illustrates. A wash solution ("waste") is directed to and flows through a separation vessel housing the capture bed ("cell stack"). When the wash solution flows through the vessel and a voltage is applied to the cell stack (not shown), ionic contaminants bound to the cell stack are liberated. Upon opening a valve ("waste valve"), the wash solution flow containing the liberated ionic contaminants (PFOA and / or PFOS) is directed through a regeneration outlet line to a regeneration vessel ("waste reservoir"). A fixed ion source (in this embodiment, hydrated lime pellets) binds PFOA / PFOS. The hydrated lime pellets with bound PFOA / PFOS can be removed from the system and disposed of.

[0116] In one aspect, the present invention provides a method for regenerating a carbon bed. The method includes providing a vessel for containing a carbon bed having one or more ionic contaminants retained thereon or therein. The method also includes converting the one or more ionic contaminants retained by the carbon bed into (a) hydroxides and / or peroxides, and (b) Ca. 2+ , Mg 2+ , Zn 2+ , Sr 2+ , Al 3+ , B 3+ , and Fe 3+ The method includes contacting one or more cations selected from: (a) hydroxide and / or peroxide, and (b) one or more cations, in a single aqueous liquid or in two or more separate aqueous liquids, for contacting the one or more ionic contaminants. The method further includes contacting the one or more ionic contaminants with a flocculant. The method also includes forming a flocculant phase comprising the one or more ionic contaminants. The method also includes isolating the flocculant phase.

[0117] In some embodiments, the flocculant contacts the one or more ionic contaminants before (a) the hydroxide and / or peroxide, and / or (b) one or more cations contact the contaminants. In other embodiments, the flocculant contacts the one or more ionic contaminants after (a) the hydroxide and / or peroxide, and / or (b) one or more cations contact the contaminants. Also, in some embodiments, the flocculant contacts the one or more ionic contaminants simultaneously with (a) the hydroxide and / or peroxide, and / or (b) one or more cations (e.g., a single aqueous liquid or two or more aqueous liquids include the flocculant).

[0118] In some embodiments, the flocculant comprises an oil, a terpene, a fatty acid ester, or any combination thereof. For example, the oil may be selected from coconut oil, corn oil, cottonseed oil, olive oil, palm oil, peanut oil, rapeseed oil (e.g., canola oil), safflower oil, sesame oil, soybean oil, sunflower oil, or any combination thereof. In some embodiments, the oil comprises safflower oil, rapeseed oil, or any combination thereof. In some embodiments, the terpene is selected from myrcene, menthol, limonene, carvone, hinokitiol, linalool, or any combination thereof. In some embodiments, the fatty acid ester is ethyl octanoate. Also, in some embodiments, the flocculant is selected from safflower oil, rapeseed oil, limonene, ethyl octanoate, or any combination thereof.

[0119] IV. Systems for capturing pollutants

[0120] Another aspect provided herein is a system for trapping ionic contaminants, i.e., a "trapping system." The trapping system includes a separation vessel housing a trapping bed configured to trap ionic contaminants in an aqueous mixture flowing through the separation vessel. In some embodiments, the system also provides for regeneration of the trapping bed as an integrated trapping and regeneration system, i.e., an "integrated system." The integrated system may include any of the features of the regeneration system and / or trapping system described herein.

[0121] The capture system includes a separation vessel, a capture bed disposed therein, and an intake line fluidly connected to the vessel and configured to couple one or more ionic contaminants in the contaminated aqueous mixture to the capture bed by introducing a flow of the contaminated aqueous mixture into the vessel, and optionally further includes an electrode in electrical contact with the capture bed, a power supply in electrical contact with the electrode in electrical contact with the capture bed and configured to apply a voltage to the electrode, and a controller configured to control and regulate the voltage applied to the electrode from the power supply.

[0122] The integrated capture and regeneration system includes a capture system and further includes a regeneration line fluidly connected to the vessel and configured to introduce a flow of an aqueous wash solution into the vessel to wash ionic contaminants from the capture bed.

[0123] In some embodiments, the capture system further includes a pump fluidly connected to the intake line and configured to pump the contaminated aqueous mixture into the separation vessel, hi some embodiments, the capture system further includes a valve fluidly connected to the intake line and configured to control the flow rate of the contaminated aqueous mixture into the separation vessel.

[0124] In some embodiments, the system is a non-electric system.

[0125] In some embodiments, the system is an electrification system comprising an electrode, a power source, and a controller as described herein. In some embodiments, the controller is configured to reduce or reverse the current applied from the power source. In some embodiments, the controller is further configured to reduce the voltage applied to the electrode, reverse the polarity of the voltage applied to the electrode, eliminate the voltage applied to the electrode, or any combination thereof. As described in the methods below, the power source is configured to apply a first voltage to the electrode while the contaminated aqueous mixture flows through the capture bed (during the capture cycle). Eliminating, reducing, or reversing the current while the wash solution flows through the capture bed (during the regeneration cycle) helps promote the release of bound contaminants from the capture bed.

[0126] In some embodiments, the capture bed (e.g., an activated carbon bed) is pretreated to improve its performance. Specifically, the pretreatment includes (a) contacting the carbon bed with hydroxides and / or peroxides; (b) contacting the bed with Ca 2+ , Mg 2+ , Zn 2+ , Sr 2+ , Al 3+ , B 3+ , and Fe 3+ (c) contacting the carbon bed with one or more cations selected from the group consisting of (a) sucrose, (b) sucrose, (c) sucrose, (d) sucrose, (e.g., two or more, three or more, or all four of) the following: (i ...

[0127] In some embodiments, the capture bed (e.g., an activated carbon bed) is surface-modified with a functional group selected from the group consisting of an acid, a hydroxide, a chloride, a bromide, a fluoride, an ether, an epoxide, a quinone, a ketone, an aldehyde, a pyrrole, a thiophene, and any combination thereof.

[0128] In some embodiments, the trapping bed is at least partially conductive. In some embodiments, the trapping bed is porous. In some embodiments, the trapping bed is an activated carbon bed. In some embodiments, the trapping bed is an ion exchange resin bed. In some embodiments, the trapping bed is a composite of activated carbon and ion exchange resin. In some embodiments, the trapping bed is an activated carbon metal oxide composite. In some embodiments, the trapping bed is a FILTRASORB® activated carbon bed by Calgon Carbon. In some embodiments, the trapping bed comprises BLACK PEARLS® 2000 (activated graphite) by Cabot corporation. In some embodiments, the trapping bed comprises PBX51 (activated graphite) by Cabot corporation. In some embodiments, the carbon bed comprises sintered carbon. In some embodiments, the carbon bed comprises F400 granular activated carbon by Calgon Carbon.

[0129] In some embodiments, the capture bed comprises a powder, granules, beads, pellets, fabric, felt, non-woven fabric, or composite comprising a material selected from carbon, nitrogen-doped carbon, silicon-doped carbon, boron-doped carbon, charcoal, graphite, biochar, coke, carbon black, or any combination thereof, In some embodiments, the capture bed comprises activated charcoal powder, granules, pellets, beads, or any combination thereof.

[0130] In some embodiments, the capture bed is about 100 m 2 / g~about 2000m 2 The trapping bed comprises activated carbon having an average surface area of ​​about 100 μm / g. In some embodiments, the trapping bed has a conductivity of about 0.01 S / cm to about 100 S / cm. In some embodiments, the trapping bed has a porosity of about 30% to about 95%.

[0131] In some embodiments, the capture bed is surface modified with a functional group selected from the group consisting of acid, hydroxide, chloride, bromide, fluoride, ether, epoxide, quinone, ketone, aldehyde, pyrrole, thiophene, and any combination thereof. In some embodiments, the capture bed has an ionic complexing species bound thereto. In some embodiments, the ionic complexing species is Ca 2+ , Mg 2+ , Al 3+ , phosphate, borate, or silicate. In some embodiments, the ionic complexing species is an alkali ion mixed with a fatty acid or wax.

[0132] In some embodiments, the capture bed further comprises a binder dispersed within the capture bed. In some embodiments, the binder comprises a wax, a starch, a sugar, a polysaccharide, or any combination thereof. In some embodiments, the wax is a polyethylene wax. In some embodiments, the wax is a carnauba wax.

[0133] In some embodiments, the capture bed is positioned longitudinally along the flow axis of the separation vessel such that the contaminated aqueous mixture flows past the capture bed, while in other embodiments, the capture bed is positioned transversely of the separation vessel such that water flows through the capture bed.

[0134] In some embodiments, the capture bed is adjacent to a separator, hi some embodiments, the capture bed is wrapped in, enclosed within, or sandwiched between two separators.

[0135] In some embodiments, the capture system further comprises a second separation vessel housing a second capture bed and a second electrode in electrical contact with the second capture bed, hi some embodiments, the power source or the second power source is configured to apply a voltage to the second electrode in electrical contact with the second capture bed.

[0136] In some embodiments, the separation vessel further contains a second capture bed and a second electrode in electrical contact with the second capture bed. In some embodiments, the second capture bed is adjacent to the first capture bed and a separator is disposed between the first capture bed and the second capture bed. In some embodiments, the separator is disposed around the first and second capture beds in a Z-fold, S-fold, or C-fold configuration. In some embodiments, the separator is disposed around one or more capture beds in a spiral or jelly roll configuration. In some embodiments, the power source is configured to apply a positive voltage to one of the first and second capture beds and a negative voltage to the other of the first and second capture beds.

[0137] In some embodiments, the separation vessel comprises a stack including a plurality of trapping beds. In some embodiments, the plurality of trapping beds in the stack are separated from one another by one or more separators. In some embodiments, the plurality of trapping beds are in electrical contact with the first or second electrode.

[0138] In some embodiments, the power source is configured to apply a positive voltage to a first electrode, the first electrode being in electrical contact with a first plurality of capture beds, and the power source is configured to apply a negative voltage to a second electrode, the second electrode being in electrical contact with a second plurality of capture beds.

[0139] In some embodiments, a first plurality of capture beds are stacked alternatingly with a second plurality of capture beds.

[0140] In some embodiments, the vessel is a pipe, a column, or a tank. The capture bed (e.g., a carbon bed) can have any shape.

[0141] In some embodiments, the separator comprises a porous plastic. In some embodiments, the porous plastic is a plastic mesh. In some embodiments, the separator comprises an inert material. Suitable materials for the separator include nylon, polyamide, polypropylene, and HDPE.

[0142] FIG. 1 illustrates an exemplary capture system according to one embodiment of the present invention. In this embodiment, a separation vessel or column 102 (e.g., PVC pipe) houses a stack 104 of carbon powder capture beds 104a-d. The stack 104 is organized with each carbon powder capture bed 104a-d wrapped with a non-woven separator 106a-d. Additional stacks can be added and the column 102 lengthened to accommodate the desired carbon load. The stack 104 is configured with the wrapped carbon powder capture beds 104a-d arranged transversely of the vessel 102 such that flow through the vessel 102 flows through each capture bed 104a-d of the stack 104. An electrode 108 (or "current collector") made from a graphite-filled polymer is in electrical contact with the carbon powder capture beds 104a-d. The electrode 108 is electrically coupled to a power source 150. The first electrode 108a is inserted vertically through the stack 104 and is in electrical contact with the first 104a and third 104c trapping beds of the stack, but is electrically insulated from the second 104b and fourth 104d trapping beds of the stack. A non-conductive tape 110 wraps a portion of the first electrode 108a in the electrically insulated areas of the second and fourth trapping beds. The second electrode 108b is inserted vertically through the stack 104 (and is separated from the first electrode 108a) and is in electrical contact with the second 104b and fourth 104d trapping beds of the stack, but is electrically insulated from the first 104a and third 104c trapping beds. A non-conductive tape 110 wraps a portion of the second electrode 108b in the electrically insulated areas of the first 104a and third 104c trapping beds. An intake line 112 is fluidly connected to a first end of the separation vessel 102, and an outlet line 116 is fluidly connected to a second end of the separation vessel 102. The inlet line 112 includes an inlet valve 114. The outlet line 116 includes an outlet valve 118.

[0143] FIG. 2 is a schematic diagram of an exemplary system 200 according to another embodiment of the present invention. FIG. 2A shows a capture system 200a used to capture contaminants, specifically PFOA or PFOS, from a water source. An intake line 212 is fluidly connected to a vessel 202 containing a cell stack 204 and is configured to supply water requiring treatment due to high concentrations of PFOA and / or PFOS (e.g., having levels of PFOA and / or PFOS above an upper limit defined by the EPA or other regulatory agency) into the vessel 202. The cell stack 204 includes stacked capture beds, optionally with separators between the beds. The outlets include valves 218a, 218b for a clean water outlet and a wastewater (i.e., wash) outlet. FIG. 2B shows a regeneration system 200b as described above. The regeneration system of FIG. 2B can be equipped with the system of FIG. 2A as part of an integrated system.

[0144] FIG. 3A is a process diagram of an exemplary integrated system 300 according to another embodiment of the present invention. In this embodiment, a raw water tank 308 contains a contaminated aqueous mixture requiring removal of ionic contaminants. The raw water tank 308 is fluidly connected to a pump 314 ("Pump 1") via an intermediate valve 312 for controlling the flow rate. Pump 1 (314) is fluidly connected to an inlet 316 of a separation vessel 302 (e.g., an activated carbon EDI filtration column) that contains an activated carbon capture bed 304. A voltage / current source 306 is electrically connected to the capture bed 304 of the separation vessel 302. An outlet 318 of the column 302 is fluidly connected to a clean water tank 324 via an intermediate valve 322. The intermediate valve 322 is also fluidly connected to the raw water tank 308 via a recirculation line 326 that optionally recirculates the liquid for one or more additional cycles of contaminant removal. The raw water tank 308 is also fluidly connected to another pump 330 ("Pump 2") through the same intermediate valve 312 that controls the flow rate to Pump 1 (314). Pump 2 (330) is fluidly connected to a second separation vessel 332 (activated graphite EDI concentrator column) that contains an activated graphite capture bed 334. A voltage / current source 336 is electrically connected to the activated graphite bed 334. The second separation vessel 332 is fluidly connected to the clean water tank 308 and to the recirculation valve 322.

[0145] Continuing to refer to FIG. 3A, a regeneration vessel 328 (waste tank) containing wash fluid is fluidly connected to both Pump 1 (314) and Pump 2 (330) and both separation vessels 302, 332. The wash fluid that has flowed through the capture beds 304 and / or 334 can be referred to as the extract, which is fluidly connected to a precipitator 338. The precipitator 338 is also fluidly connected to a regeneration fluid tank 340 via another pump 342 ("Pump 3"). The regeneration fluid tank 340 contains counterions in a liquid medium. The precipitator 338 is fluidly connected to a settler 344 for removing precipitated solids from the extract after mixing with the counterions. The settler 344 is also fluidly connected to a filter 346 for further removing solids from the liquid phase exiting the settler. The system 300 can be controlled by a PLC controller 348.

[0146] Figure 3B is substantially similar to Figure 3A, except that a layer of flocculant 350 is included in the settler 338'. In this manner, flowing the aqueous wash fluid containing ionic contaminants from one or both of the separation vessels 302, 332 into the settler 338' may cause the aqueous wash fluid to come into contact with the flocculant, thereby facilitating and / or promoting flocculation of the ionic contaminants alone or in combination with the sequestration agent. It will be appreciated that the layer of flocculant 350 may be located in any suitable location downstream of the separation vessels 302, 332 to facilitate and / or promote flocculation of the ionic contaminants before the aqueous wash fluid is recycled through the separation vessels 302, 332.

[0147] V. Methods for Capturing Contaminants

[0148] Another aspect provided herein is a method for trapping ionic contaminants, i.e., a "trapping method." The trapping method includes flowing an aqueous mixture containing one or more ionic contaminants into a separation vessel containing a trapping bed to bind the one or more ionic contaminants to the trapping bed, thereby removing the one or more ionic contaminants from the aqueous mixture. In some embodiments, the method includes regeneration of the trapping bed as part of an integrated trapping and regeneration method, i.e., an "integrated method."

[0149] In some embodiments, the capture method further includes pre-treating the capture bed prior to the first capture. Pre-treatment can include contacting (e.g., rinsing) the capture bed according to a regeneration process described in any embodiment herein. For example, the method can include (a) contacting the carbon bed with hydroxide and / or peroxide; (b) contacting the carbon bed with Ca 2+ , Mg 2+ , Zn 2+ , Sr 2+ , Al 3+ , B 3+ , and Fe 3+ (c) rinsing the carbon bed with an aqueous acidic solution; and (d) rinsing the carbon bed with water.

[0150] In some embodiments, the trapping method further comprises applying a voltage to an electrode in electrical contact with the trapping bed such that the one or more ionic contaminants bind to the trapping bed. The applied voltage enhances the binding of the one or more ionic contaminants to the trapping bed. The method of applying a voltage is referred to as an electrification method.

[0151] The integrated method further includes a regeneration cycle including flowing an aqueous wash solution into the separation vessel, and the charging method optionally further includes adjusting the voltage applied to the electrodes such that one or more ionic contaminants bound to the trapping bed are released from the trapping bed and washed from the trapping bed by the aqueous wash solution. The adjusted voltage serves to drive the release of the bound ionic contaminants from the trapping bed. The integrated method, and in particular its regeneration cycle, may include any of the steps and features of the regeneration method described above.

[0152] In some embodiments, applying a voltage to the electrode includes passing a current through the electrode, and adjusting the voltage includes reducing or reversing the current through the electrode. In some embodiments, the voltage applied to the electrode during capture of the contaminant has a positive polarity of about 0.01 V to about 2.2 V. In some embodiments, the voltage applied to the electrode during capture of the contaminant has a positive polarity of about 0.01 V to about 1.6 V. In some embodiments, adjusting the voltage to liberate the ionic contaminant includes reducing the current to generate an adjusted voltage having a positive polarity of about 0.01 V to about 1.5 V (e.g., about 0.01 V to about 1.2 V). In some embodiments, adjusting the voltage to liberate the ionic contaminant includes reversing the current to generate an adjusted voltage having a negative polarity of about -0.01 V to about -2.2 V or about -0.01 V to about -1.6 V. In some embodiments, adjusting the voltage to liberate the ionic contaminant includes applying an AC voltage with an appropriate DC offset.

[0153] In some embodiments, the contaminated aqueous mixture is flowed into the vessel at a rate of about 5 to about 400 liters per minute per square meter of capture bed. In some embodiments, the contaminated aqueous mixture is flowed into the vessel at a rate of about 80 to about 240 liters per minute per square meter of capture bed. In some embodiments, the contaminated aqueous mixture is flowed into the vessel at a rate of about 0.01 to about 10 liters per minute per kilogram of capture bed. In some embodiments, the capture bed has a mass of about 4,000 to about 10,000 kilograms. In some embodiments, the pressure drop across the capture bed is about 1 psi to about 200 psi.

[0154] In some embodiments, the aqueous wash solution is poured into the vessel at a rate of about 5 to about 400 liters per minute per square meter of capture bed. In some embodiments, the aqueous wash solution is poured into the vessel at a rate of about 80 to about 240 liters per minute per square meter of capture bed. In some embodiments, the aqueous wash solution is poured into the vessel at a rate of about 0.01 to about 10 liters per minute per kilogram of capture bed.

[0155] In some embodiments, the capture method further comprises binding an ionic complexing species to the capture bed prior to flowing the contaminated aqueous mixture into the vessel, such that as the contaminated aqueous mixture flows into the vessel, the ionic contaminants bind to the capture bed by forming a complex with the ionic complexing species, which complex binds to the capture bed. In some embodiments, the ionic complexing species is Ca 2+ , Mg 2+ , phosphate, borate, or silicate. In some embodiments, the ionic complexing species is an alkali ion mixed with a fatty acid or wax.

[0156] In some embodiments, the capture bed is positioned within the vessel such that the contaminated aqueous mixture flows past the capture bed. In some embodiments, the capture bed is positioned within the vessel such that the contaminated aqueous mixture flows through the capture bed.

[0157] In some embodiments, the capture method further includes flowing the contaminated aqueous mixture into a second vessel containing a second capture bed and a second electrode in electrical contact with the second capture bed, and applying a voltage to the second electrode in electrical contact with the second capture bed.

[0158] In some embodiments, the container further contains a second capture bed and a second electrode in electrical contact with the second capture bed, and the capture method further comprises applying a voltage to the second electrode in electrical contact with the second capture bed. In some embodiments, the second capture bed is adjacent to the first capture bed, and a separator is disposed between the first capture bed and the second capture bed. In some embodiments, a positive voltage is applied to one of the first and second capture beds, and a negative voltage is applied to the other of the first and second capture beds.

[0159] In some embodiments, the vessel comprises a capture bed stack including a plurality of capture beds. In some embodiments, the plurality of capture beds are separated from one another by one or more separators. In some embodiments, the plurality of capture beds are in electrical contact with a first or second electrode. In some embodiments, the capture method further comprises applying a positive voltage to a first electrode, the first electrode being in electrical contact with the first plurality of capture beds; and applying a negative voltage to a second electrode, the second electrode being in electrical contact with the second plurality of capture beds. In some embodiments, the first plurality of capture beds are stacked alternately with the second plurality of capture beds.

[0160] In some embodiments, the capture method further comprises surface-modifying the capture bed with a functional group selected from the group consisting of an acid, a hydroxide, a chloride, a bromide, a fluoride, an ether, an epoxide, a quinone, a ketone, an aldehyde, a pyrrole, a thiophene, and any combination thereof.

[0161] In some embodiments, the ionic contaminant comprises an organic end with an ionic moiety. In some embodiments, the ionic contaminant is selected from the group consisting of polyfluoroalkyl ions, borates, phosphates, polyphosphates, sulfates, organic acids, fatty acids, humic substances, short chain PFAS, water soluble pharmaceuticals, detergents, water soluble insecticides, water soluble fungicides, water soluble bactericides, and any combination thereof. In some embodiments, the ionic contaminant is a polyfluoroalkyl ion. In some embodiments, the polyfluoroalkyl ion is perfluorooctane sulfonate or perfluorooctanoate.

[0162] In some embodiments, the contaminated aqueous mixture further comprises inorganic contaminants. In some embodiments, the inorganic contaminants comprise iron or manganese. In some embodiments, the inorganic contaminants in the contaminated aqueous mixture result in scale formation or inorganic precipitate formation on the capture bed. The scale or inorganic precipitate may be removed by using one or more additives in the cleaning solution or in a separate rinse solution. In some embodiments, the use of the additive(s) reduces the time required to regenerate the capture bed and / or reduces the amount of cleaning solution required to regenerate the capture bed.

[0163] The system of FIG. 2A can also be described in terms of the capture method it illustrates. Water containing high concentrations of PFOA and / or PFOS contaminants is flowed into a separation vessel containing multiple capture beds arranged in a stack (the "cell stack"). As the water flows through the cell stack, PFOA and / or PFOS ionic contaminants bind to the capture beds. The water flow through the separation vessel is stripped of bound contaminants, and water containing low concentrations of PFOA and / or PFOS leaves the separation vessel via an outlet line. Flow through the outlet line is controlled by a valve that is open during the capture cycle ("system in use"). A second outlet line, for use during the regeneration cycle, is closed.

[0164] The system of Figure 3A can also be described in terms of an integrated capture and regeneration process. During the capture cycle of the integrated process, contaminated water flows from a raw water tank into two separation vessels (an activated carbon EDI filtration column and an activated graphite EDI concentration column). This flow is controlled by valves and pumps for each separation vessel as shown. A voltage is applied to the capture beds in each separation vessel. Water from which contaminants have been removed by the capture beds flows to a clean water tank, the flow of which is controlled by a further valve. Optionally, the outlet flow of the separation vessel may be recirculated back to the raw water tank, controlled by a recirculation valve, for additional purification cycle(s).

[0165] With continued reference to FIG. 3A, during the regeneration cycle, wash liquor from the waste tank flows into the separation vessel, again controlled using the same valves and pumps as during the capture cycle. The voltage is adjusted during the regeneration cycle to drive the liberation of bound contaminants from the capture bed as the wash liquor flows into the separation vessel. The wash liquor containing the liberated contaminants ("extract") flows into the precipitator and is mixed with the regeneration fluid pumped into the precipitator. The regeneration fluid contains a sequestrant (e.g., counterion) that forms a flocculated contaminant phase with the liberated contaminants. The flocculated contaminant phase precipitates from the wash liquor in the precipitator, and the solids are collected in the settler and removed. The wash liquor exiting the settler / settler is filtered and returned for continued use in washing the capture bed.

[0166] Referring to Figure 3B, the wash liquor ("extract") containing the liberated contaminants is contacted with a layer of flocculant that facilitates and / or promotes the formation of an aggregate-forming phase. As shown, the layer of flocculant is disposed within the settler. However, the layer of flocculant may be located in any suitable location downstream of the separation vessel to facilitate and / or promote the aggregation of ionic contaminants before the aqueous wash fluid is recycled through the separation vessel.

[0167] In one aspect, the present invention provides a method for removing contaminants from an aqueous mixture. The method includes flowing a contaminated aqueous mixture containing one or more ionic contaminants into a vessel containing a carbon bed, where the one or more ionic contaminants are retained by the carbon bed. The method also includes converting the one or more ionic contaminants retained by the carbon bed into (a) hydroxides and / or peroxides, and (b) Ca. 2+ , Mg 2+ , Zn 2+ , Sr 2+ , Al 3+ , B 3+ , and Fe 3+ The method includes contacting one or more cations selected from: (a) hydroxide and / or peroxide, and (b) one or more cations, in a single aqueous liquid or in two or more separate aqueous liquids, for contacting the one or more ionic contaminants. The method further includes contacting the one or more ionic contaminants with a flocculant. The method also includes forming a flocculant phase comprising the one or more ionic contaminants. The method also includes isolating the flocculant phase.

[0168] In some embodiments, the flocculant contacts the one or more ionic contaminants before (a) the hydroxide and / or peroxide, and / or (b) one or more cations contact the contaminants. In other embodiments, the flocculant contacts the one or more ionic contaminants after (a) the hydroxide and / or peroxide, and / or (b) one or more cations contact the contaminants. Also, in some embodiments, the flocculant contacts the one or more ionic contaminants simultaneously with (a) the hydroxide and / or peroxide, and / or (b) one or more cations (e.g., a single aqueous liquid or two or more aqueous liquids include the flocculant).

[0169] In some embodiments, the flocculant comprises an oil, a terpene, a fatty acid ester, or any combination thereof. For example, the oil may be selected from coconut oil, corn oil, cottonseed oil, olive oil, palm oil, peanut oil, rapeseed oil (e.g., canola oil), safflower oil, sesame oil, soybean oil, sunflower oil, or any combination thereof. In some embodiments, the oil comprises safflower oil, rapeseed oil, or any combination thereof. In some embodiments, the terpene is selected from myrcene, menthol, limonene, carvone, hinokitiol, linalool, or any combination thereof. In some embodiments, the fatty acid ester is ethyl octanoate. Also, in some embodiments, the flocculant is selected from safflower oil, rapeseed oil, limonene, ethyl octanoate, or any combination thereof.

[0170] In another aspect, the present invention provides a method for removing contaminants from an aqueous mixture. The method includes flowing a contaminated aqueous mixture containing one or more ionic contaminants into a vessel containing a carbon bed, where the one or more ionic contaminants are retained by the carbon bed. The method also includes converting the one or more ionic contaminants retained by the carbon bed into (a) hydroxides and / or peroxides, and (b) Ca. 2+ , Mg 2+ , Zn 2+ , Sr 2+ , Al 3+ , B 3+ , and Fe 3+(a) hydroxides and / or peroxides, and (b) one or more cations are provided in a single aqueous liquid or two or more separate aqueous liquids for contacting the one or more ionic contaminants. The method further includes contacting the single aqueous liquid or the two or more separate aqueous liquids with a flocculant to form a flocculant contaminant phase comprising the one or more ionic contaminants. The step of contacting the single aqueous liquid or the two or more separate aqueous liquids with a flocculant occurs after contacting the one or more ionic contaminants retained by the carbon bed with (a) hydroxides and / or peroxides, and (b) one or more cations. The method also further includes isolating the flocculant contaminant phase.

[0171] In some embodiments, the flocculant comprises an oil, a terpene, a fatty acid ester, or any combination thereof. For example, the oil may be selected from coconut oil, corn oil, cottonseed oil, olive oil, palm oil, peanut oil, rapeseed oil (e.g., canola oil), safflower oil, sesame oil, soybean oil, sunflower oil, or any combination thereof. In some embodiments, the oil comprises safflower oil, rapeseed oil, or any combination thereof. In some embodiments, the terpene is selected from myrcene, menthol, limonene, carvone, hinokitiol, linalool, or any combination thereof. In some embodiments, the fatty acid ester is ethyl octanoate. Also, in some embodiments, the flocculant is selected from safflower oil, rapeseed oil, limonene, ethyl octanoate, or any combination thereof.

[0172] In a further aspect, the present invention provides a method for removing contaminants from an aqueous mixture. The method includes flowing a contaminated aqueous mixture containing one or more ionic contaminants into a vessel containing a carbon bed, where the one or more ionic contaminants are retained by the carbon bed. The method also includes contacting the one or more ionic contaminants retained by the carbon bed with (a) sodium hydroxide and / or hydrogen peroxide, and (b) calcium hydroxide, aluminum hydroxide, and / or aluminum sulfate. The (a) sodium hydroxide and / or hydrogen peroxide, and (b) calcium hydroxide, aluminum hydroxide, and / or aluminum sulfate are provided in a single aqueous liquid or two or more separate aqueous liquids for contacting the one or more ionic contaminants. The method further includes contacting the one or more ionic contaminants with a flocculant. The method also includes forming a flocculant contaminant phase containing the one or more ionic contaminants. The method also includes isolating the flocculant contaminant phase.

[0173] In some embodiments, the flocculant contacts one or more ionic contaminants before (a) sodium hydroxide and / or hydrogen peroxide, and / or (b) calcium hydroxide, aluminum hydroxide, and / or aluminum sulfate contact the contaminant. In other embodiments, the flocculant contacts one or more ionic contaminants after (a) sodium hydroxide and / or hydrogen peroxide, and / or (b) calcium hydroxide, aluminum hydroxide, and / or aluminum sulfate contact the contaminant. Also, in some embodiments, the flocculant contacts one or more ionic contaminants simultaneously with (a) sodium hydroxide and / or hydrogen peroxide, and / or (b) calcium hydroxide, aluminum hydroxide, and / or aluminum sulfate (e.g., a single aqueous liquid or two or more aqueous liquids include the flocculant).

[0174] In some embodiments, the flocculant comprises an oil, a terpene, a fatty acid ester, or any combination thereof. For example, the oil may be selected from coconut oil, corn oil, cottonseed oil, olive oil, palm oil, peanut oil, rapeseed oil (e.g., canola oil), safflower oil, sesame oil, soybean oil, sunflower oil, or any combination thereof. In some embodiments, the oil comprises safflower oil, rapeseed oil, or any combination thereof. In some embodiments, the terpene is selected from myrcene, menthol, limonene, carvone, hinokitiol, linalool, or any combination thereof. In some embodiments, the fatty acid ester is ethyl octanoate. Also, in some embodiments, the flocculant is selected from safflower oil, rapeseed oil, limonene, ethyl octanoate, or any combination thereof.

[0175] In yet another aspect, the present invention provides a method for removing contaminants from an aqueous mixture. The method includes flowing a contaminated aqueous mixture containing one or more ionic contaminants into a vessel containing a carbon bed, where the one or more ionic contaminants are retained by the carbon bed. The method also includes contacting the one or more ionic contaminants retained by the carbon bed with (a) sodium hydroxide and / or hydrogen peroxide, and (b) calcium hydroxide, aluminum hydroxide, and / or aluminum sulfate. The (a) sodium hydroxide and / or hydrogen peroxide, and (b) calcium hydroxide, aluminum hydroxide, and / or aluminum sulfate are provided in a single aqueous liquid or two or more separate aqueous liquids for contacting the one or more ionic contaminants. The method further includes contacting the single aqueous liquid or two or more separate aqueous liquids with a flocculant to form a flocculant contaminant phase containing the one or more ionic contaminants. The step of contacting the single aqueous liquid or two or more separate aqueous liquids with a flocculant occurs after contacting the one or more ionic contaminants retained by the carbon bed with (a) sodium hydroxide and / or hydrogen peroxide, and (b) calcium hydroxide, aluminum hydroxide, and / or aluminum sulfate. The method also further includes isolating the flocculant contaminant phase.

[0176] In some embodiments, the flocculant comprises an oil, a terpene, a fatty acid ester, or any combination thereof. For example, the oil may be selected from coconut oil, corn oil, cottonseed oil, olive oil, palm oil, peanut oil, rapeseed oil (e.g., canola oil), safflower oil, sesame oil, soybean oil, sunflower oil, or any combination thereof. In some embodiments, the oil comprises safflower oil, rapeseed oil, or any combination thereof. In some embodiments, the terpene is selected from myrcene, menthol, limonene, carvone, hinokitiol, linalool, or any combination thereof. In some embodiments, the fatty acid ester is ethyl octanoate. Also, in some embodiments, the flocculant is selected from safflower oil, rapeseed oil, limonene, ethyl octanoate, or any combination thereof. EXAMPLES

[0177] VI. Working Examples

[0178] Example 1: Regeneration of carbon substrates

[0179] An experiment was conducted to test the regeneration of carbon substrates using calcium hydroxide and calcium chloride. The experiment tested the capture, regeneration, and sequestration of (i) octanoic acid and (ii) PFOA in carbon substrates using calcium hydroxide or calcium chloride as sequestration agents. Octanoic acid is an analogue of PFAS, which has similar aquatic behavior as real PFAS but without the disposal issues. Visual indicators and mass measurements were used to determine the outcome of the experiment.

[0180] FIG. 4 shows a flow chart of the test method. Either granular activated carbon (GAC) or St Mary's carbon beads were selected as the first carbon substrate. The dry mass of the substrate was recorded. The substrate was then immersed in water and the wet mass was recorded. The substrate was then dried in an oven and the mass after drying was recorded. The substrate was then immersed in water and then immersed overnight in a mixture of water and a specified recorded mass of pollutant (either octanoic acid (OA) or PFOA). The wet mass of the substrate was then recorded to determine the capture of OA / PFOA. The substrate was then immersed overnight in a solution of water and a specified recorded mass of sequestrant (either Ca(OH)2 or CaCl2). In the case of CaCl2, NaOH was also added. After soaking and washing, the wet mass of the substrate was recorded. The substrate was then dried in an oven and the dry mass after drying was recorded. The sequestrant solution was dried and the mass of the precipitate from the solution was recorded.

[0181] The same basic procedure can then be repeated for the second and subsequent rounds of capture, regeneration, and sequestration using mass measurements. In this experiment, the second and third rounds were completed. The dried substrate from the final step of round 1 was immersed in water and the wet mass of the substrate was recorded. The substrate was then immersed overnight in water and contaminant (either octanoic acid (OA) or PFOA). The wet mass of the substrate was then recorded to determine the capture of OA / PFOA. The substrate was then immersed in a solution of water and sequestration agent (either Ca(OH)2 or CaCl2). In the case of CaCl2, NaOH was also added. After soaking and washing, the wet mass of the substrate was recorded. The substrate was then dried in an oven and the dry mass after drying was recorded. The sequestration agent solution was dried and the mass of the precipitate from the solution was recorded.

[0182] Tables 1-4 show the initial wash procedure and mass measurements of the experiment over the three rounds of capture, regeneration, and sequestration. Table 5 shows the recovered mass of sediment collected in each round. Figure 5 shows the visual findings of St. Mary's beads (activated carbon beads) over the first round of testing.

[0183] These results indicate that the carbon substrates were able to releasably capture OA and PFOA, and that the sequestration agents (calcium hydroxide or calcium chloride) were able to bind OA or PFOA, release them from the carbon substrates, and sequester them as precipitates. This process was reproducible, demonstrating that OA and PFOA could be captured in the carbon substrates, which could then be regenerated for multiple uses.

[0184] [Table 1]

[0185] [Table 2]

[0186] [Table 3]

[0187] [Table 4]

[0188] [Table 5]

[0189] Example 2: Regeneration of carbon beds by acid washing

[0190] To evaluate the regeneration capacity, the sorption isotherms of the regenerated activated carbon were compared with those of fresh activated carbon (Calgon F400) for the model PFAS compound perfluorooctanoic acid (PFOA).

[0191] procedure:

[0192] [Table 6]

[0193] Calgon F400 activated carbon was rinsed with DI water and dried in a vacuum oven at 100°C. 0.1 g ± 0.001 of PFOA was weighed into a 2 L clean glass bottle. 2 L of deionized water was added to the bottle via a volumetric flask. Actual input weight and volume were recorded. Stirred until the PFOA was completely dissolved.

[0194] 102.70 g ± 1 g of DI water was weighed into each of twenty 250 ml Erlenmeyer flasks according to Table 6. 22.1 mL of PFOA stock solution was added using a micropipette (1277345 μg / kg). Using a calibrated balance, 0.75 ± 0.001 g of Calgon F400 activated carbon was weighed into each of twenty glass 250 ml Erlenmeyer flasks and shaken.

[0195] 2 oz. glass sample vials were prepared by rinsing with DI water and removing the foam seals from the caps. After 18 hours on the shaker, a 2 oz. sample was removed from each condition using a pipette (rinsed with DI water), changing tips for each sample, taking care not to remove the activated carbon, and rinsing the vial with sample before filling. The remaining PFOA solution was removed from each flask and discarded.

[0196] A solution of 1 g / L Ca(OH)2 (regeneration fluid) was prepared and mixed on a stir plate until all Ca(OH)2 was dissolved. A 1% acetic acid wash was prepared by diluting a 5% vinegar solution. 125 ml of Ca(OH)2 stock solution was measured into each flask and shaken at 150 rpm for 1 hour. The regeneration solution was removed by pouring off the liquid. Rinsing continued according to Table 6. All subsequent regeneration fluid rinses were shaken at 150 rpm for 1 hour, followed by an acid or water rinse at 150 rpm for 30 minutes. All acid rinses were completed after the regeneration wash(s) and before the water wash. The solution was poured off before the next rinse.

[0197] After rinsing, each flask was recharged with the 225834.6572 μg / kg PFOA solution. 102.70 g ± 1 g of DI water was weighed out into each of twenty 250 ml Erlenmeyer flasks according to Table 6. 22.1 mL of PFOA stock solution was added (1277345.346 μg / kg). The flasks were gently tilted to ensure all the activated carbon was submerged in the water and not sticking to the sides and placed on a shaker at 150 rpm for 18 hours.

[0198] All samples were run by UV-Visible spectroscopy to measure the equilibrium PFOA concentration after regeneration. The pH was checked when the samples were taken.

[0199] UV-Visible Spectroscopy Procedure

[0200] Using a micropipette, DI water, and the PFOA batch solution, two calibration standards were prepared at 10 and 11 points, respectively. A 10-point curve was used for the cleaned samples without the acid rinse after regeneration, using 1.5 mL of the following standards: 0, 600.36, 1000.59, 2000.33, 4257.84, 10644.60, 14902.44, 19160.28, 25547.03, and 38320.55 μg / kg. An 11-point curve was used for fresh carbon and regenerated acid rinsed samples, using 13 mL of the following standards: 0, 50.24, 100.48, 200.12, 400.24, 800.47, 1000.59, 1500.46, 2000.33, 2554.70, and 2980.49 μg / kg. Standards were filtered into DI rinsed vials using 0.22 μm PVDF / GF syringe filters. All calibration samples were prepared by mixing the appropriate amount of standard with 2.5 mL of 1-octanol and 1 mL of methylene blue solution. Calibration samples were run with the UV-visible method to generate the calibration curve.

[0201] Each sample was filtered into a new (DI water rinsed) vial using a 0.22 μm 13 mm PVDF / GF syringe filter, and the syringe and filter were changed between samples. Samples were filtered because residual activated carbon would affect the absorbance readings. All samples were run by UV-Visible spectroscopy to measure the equilibrium PFOA concentration of the fresh activated carbon.

[0202] The UV spectrophotometer was set at 664 nm. The organic and aqueous phases separated cleanly in the test tube. The organic phase was removed and placed in a cuvette. The cuvette was placed in the UV spectrophotometer with water saturated octanol to zero the machine, then the cuvette containing the sample was placed and run to measure the UV absorbance.

[0203] The pH probe was removed from the storage solution, rinsed with deionized water, and gently wiped with a Kimwipe. The 4.01, 7.01, and 10.01 solutions were placed into vials. The probe was calibrated to 7.01, then 4.01 and 10.01, and then the pH was checked again for the 7.01 calibration. After calibration, each flask was tested directly (with carbon in the flask) while swirling the flask during the test, and the probe was rinsed for each standard.

[0204] result:

[0205] Table 7 shows the recovery of equilibrium concentration and sorption capacity of each sample. Recovery was calculated by dividing the sorption mass of fresh carbon by the sorption mass of regenerated carbon and multiplying by 100.

[0206] [Table 7]

[0207] Table 8 is a summary table showing the average sorption capacity recovery for the high and low rinses at each process step. The difference in recovery for each high and low rinse indicates the level of importance of each cleaning step (regenerating fluid, wash water, acetic acid rinse) to the recovery rate.

[0208] [Table 8]

[0209] Table 9 shows the average sorption mass and percent standard deviation for all duplicates at each condition.

[0210] [Table 9]

[0211] Table 10 is a summary table showing the average pH for the high and low rinses at each process step. The difference in pH for each high and low rinse indicates the level of importance of each cleaning step (regenerating fluid, wash water, acetic acid rinse) in changing the pH of the process.

[0212] [Table 10]

[0213] Conclusion:

[0214] This study demonstrated the success of the regeneration of carbon to capture PFOA. Recovery rates across all conditions ranged from 42.88% to 100.06%. The greatest impact on the average recovery rate of the samples appeared to be due to the acid washes. Increasing the number of regeneration rinses from 1 to 2 decreased the average recovery rate by 1.83%, whereas increasing the number of water washes from 2 to 3 increased the recovery rate by 1.20% (Table 8). However, increasing the number of acid washes from 0 to 1 increased the recovery rate by 44.08%, resulting in an average recovery rate of 99.90% for all acid washed samples (Table 8). This indicates that reducing both the number of regeneration washes and the number of water washes has little impact on the process.

[0215] The pH was also most affected by the acid wash step, decreasing on average by 2.877 for the acid washed samples (Table 10). Increasing the water rinse also decreased the pH (Table 10), likely due to rinsing off excess regeneration fluid. Increasing the regeneration rinse increased the pH slightly on average, likely due to the basic nature of the regeneration fluid.

[0216] The low percent standard deviation for the fresh samples indicated high reproducibility of the fresh carbon (Table 9). For the regenerated samples, the percent standard deviation remained below 1% for all samples except for three samples: 2 regenerated wash / 2 water wash / 0 acid wash, 1 regenerated wash / 3 water wash / 0 acid wash, and 1 regenerated wash / 2 water wash / 0 acid wash.

[0217] Example 3: Regeneration of samples containing mixed contaminants

[0218] Experiments were conducted to evaluate the performance of the remediation system to capture contaminants from composite samples that more closely resemble groundwater. Mixtures of PFOA, PFNA, and PFOS with and without humic acids were used to model the composite samples.

[0219] Calgon F400 activated carbon was rinsed with DI water and dried. Stock solutions of PFOA, K-PFOS, and PFNA were prepared. Humic acid solutions were also prepared. Fresh carbon samples were prepared and tested as shown in Table 11. Regenerated samples were also prepared and tested. For the regenerated samples, the carbon samples were exposed to the contaminant solutions shown in Table 11, allowed to reach equilibrium, then the samples were regenerated with Ca(OH)2 solution, the regenerated solution was poured off, the carbon bed samples were rinsed again with the regenerated solution, and finally, a second round of treatment of the carbon samples with the same contaminant solutions shown in Table 11 was performed. Contaminant absorption was tested in fresh and regenerated carbon bed samples with and without humic acid as shown in Table 11.

[0220] [Table 11-1] [Table 11-2]

[0221] The results of the absorption tests are shown in Figures 6-11. For both the fresh and regenerated carbon samples, the carbon bed effectively captured PFOA, PFNA, and PFOS from the mixed pollutant solution. Capture was effective both in the presence and absence of humic acid. Thus, the regenerated system was effective in capturing the mixed pollutants.

[0222] Example 4: Column Test

[0223] Given the successful regeneration in Examples 1-3, column tests were conducted to investigate a model column system with flow of contaminated and regenerated solutions through the column.

[0224] A small column (10 cm high x 1.5 cm diameter) was loaded with freshly rinsed and dried GAC (14-15 g Calgon F400) as a trapping bed. The trapping bed was rinsed with DI water and then dosed with 100 ppm PFOA solution. The filtrate was sampled every 3000 seconds until 31 samples were collected to construct the first curve of PFOA concentration in the filtrate. The dosing solution was pumped at a rate that gave an approximate contact time of 160 seconds, filtering 12-14 L through the column until sampling was complete. The regeneration fluids were pumped through the column in sequence, the amount of which was chosen to be at least 50 times the free volume of the column. The first regeneration solution was a detergent solution of octanoic acid (0.2 g in 1 L DI water). The second regeneration solution was an aluminum hydroxide solution (320 g NaOH and 3480 g Al(OH) in 16 L DI water). The third regeneration solution was a calcium hydroxide solution (24 g Ca(OH) in 2 L DI water). The fourth regeneration solution was a sodium hydroxide solution (4 g NaOH in 1 L DI water). Finally, the fifth regeneration solution was an acid wash solution (250 mL of 12.39 M HCl solution in 15.75 L DI water). Regenerated DI water was then pumped through the column until the filtrate had a pH>5. The same procedure was followed for dosing with 100 ppm PFOA solution to generate a second curve for the regenerated capture bed.

[0225] Figure 12 shows the initial and regenerated breakthrough curves for a column filtered with a 100 ppm PFOA feed solution. The feed concentration is shown as a dashed line. The initial sample vial had a lower PFOA concentration indicating capture of PFOA in the carbon bed, although some PFOA was able to pass through the column in the initial vial. The regeneration curve shows that the regenerated bed captured PFOA and closely followed the performance of the fresh bed, although the capture rate was slightly reduced.

[0226] A second separate experiment did not demonstrate the same regeneration effectiveness, and it is hypothesized that the second experiment did not provide enough regenerant fluid to regenerate the column.

[0227] It is therefore shown that the regeneration process can be effectively used in a column setup with a flow of contaminated liquid through the column.

[0228] Example 5: Regeneration column protocol

[0229] Overview: F400 granular activated carbon (GAC) is saturated with PFAS. The saturated form is referred to as "spent." The spent F400 GAC is crushed and packed into a commercial chromatography column. The column is then treated with NaOH and H2O2. The column is then further treated with two regeneration solutions, successively: first an Al2(SO4)3 solution, then a Ca(OH)2 solution. A dilute HCl solution is then used to separate out other non-PFAS contaminants and to control the pH. Finally, the GAC is rinsed with DI water. The rinse steps are then repeated for the two regeneration solutions, the HCl solution, and the DI water.

[0230] Following the above rinse step, a breakthrough curve is run to test the capacity of the column after regeneration. Column effluent and feed samples are collected and tested for PFAS concentrations. Column capacity is estimated via mass balance of the breakthrough curve and by the number of bed volumes processed before breakthrough upon reloading.

[0231] Materials and Methods:

[0232] Preparation: Rinse a new Econo-Column (1 x 10 cm, BioRad 7374011) with 50% ethanol and DI water. Inspect the bottom filter. Add 0.55 mm zirconia / silica beads to the bottom of the column, spreading them out 2-3 cm above the bottom filter. Rinse the blender with ethanol and water and pack with industrially supported GAC. Blend the GAC to reduce particle size and wet sieve through ASTM 60 and 80 mesh sieves. Dry the GAC to obtain 60 x 80 mesh industrially supported F400. Add 1.1 g of 60 x 80 mesh industrially supported F400 to the column. Then add 0.5 mm zirconia / silica beads, packing 1-2 cm above the F400 GAC. Pack all material thoroughly into the column. A piece of damp glass wool is added on top of the beads and a flow adapter is fitted to hold the column contents in place. DI water is pumped through the column to wet the F400.

[0233] Regeneration: 200 mL of 1M NaOH fluid is pumped through the column at 2.8 mL / min, followed by 200 mL of 12% food grade H2O2. Next, 2.5 L of 18.60 g / L Al2(SO4)3 fluid is pumped through the column at 2.9 mL / min, followed by 2.5 L of 4 g / L Ca(OH)2 solution in the same proportions. Next, 0.5 L of 0.1M HCl solution is pumped through the column at 2.9 mL / min. Finally, 4 L of DI water is pumped through the column at 2.9 mL / min to bring the filtrate back to pH 5. Repeat the Al2(SO4)3, Ca(OH)2, HCl, and DI water rinses using the same concentrations, volumes, and flow rates, except using 6 L of DI water.

[0234] Breakthrough test: For approximately 16 days, 25,000 BV equivalent (approximately 63 L) of contaminated water is pumped through the column at a rate of 2.9 mL / min. Samples are taken at designated intervals. Every 1000 BV, a 46 mL sample is taken. A total of 25 samples are taken.

[0235] Example 6: Regeneration in a beaker

[0236] Unground spent F400 GAC was rinsed through an 80 mesh sieve to remove fines and dried for weighing, and 2 g was weighed into a beaker. An additional 2 g was weighed out and set aside as a control.

[0237] NaOH / H2O2 pre-rinse: 150 mL of 0.1M NaOH solution was poured into a beaker and swirled for 60 minutes. The NaOH solution was poured off. 150 mL of 15 wt% H2O2 solution was poured in, swirled for 60 minutes, and poured off. This was the "pre-rinse."

[0238] Regeneration: Next, 500 mL of regeneration fluid 1 (4 g / L Ca(OH)2 or 6 g / L CaCl2) was poured into the beaker. The beaker was shaken on a shaker table for 24 hours. Regeneration fluid 1 was poured off. The GAC in the beaker was swirled with 500 mL of DI water and the water was poured off. 500 mL of regeneration fluid 2 (12.83 g / L NaAl(OH)4 or 18.6 g / L Al2(SO4)3) was poured onto the GAC in the beaker. The beaker was shaken on a shaker table for 24 hours and then regeneration fluid 2 was poured off. 500 mL of DI water was added, swirled and poured off.

[0239] Acid Rinse: 500 mL of acid solution (0.01M HCl or 0.005M H2SO4 solution) was added and swirled for 60 minutes. The acid solution was poured off and the pH was tested. The acid solution rinse was repeated until a pH of 3 or less was reached. 500 mL of DI water was slowly poured in and swirled for 15 minutes before pouring off.

[0240] The GAC from the beaker was rinsed into a test tube. The DI water was poured off and the tube was capped.

[0241] To characterize PFAS compounds in GAC before and after regeneration, eight regenerated samples were tested along with a non-regenerated sample. The eight runs were as follows: 1-No pre-rinse, HCl, Ca(OH)2, NaAl(OH)4 2- Pre-rinse, HCl, Ca(OH)2, Al2(SO4)3 3-No pre-rinse, H2SO4, Ca(OH)2, Al2(SO4)3 4- Pre-rinse, H2SO4, Ca(OH)2, NaAl(OH)4 5-No pre-rinse, HCl, CaCl2, Al2(SO4)3 6- Pre-rinse, HCl, CaCl2, NaAl(OH)4 7-No pre-rinse, H2SO4, CaCl2, NaAl(OH)4 8-Pre-rinse, H2SO4, CaCl2, Al2(SO4)3

[0242] The remaining GAC after regeneration was collected and placed in a test tube. PFAS were extracted from 100 mg of GAC by incubating each with 10 mL of methanol at 25 rpm for 24 hours, followed by applying 30 minutes of sonication. PFAS extracted from methanol were measured by LC-MS / MS. PFAS concentrations were corrected for extraction efficiency by measuring the mass percent of 1 ng of PFAS isotope surrogate recovered in the extract after spiking prior to extraction.

[0243] result:

[0244] Table 12 shows the concentrations (μg / g) of PFAS extracted from each GAC.

[0245] [Table 12]

[0246] Table 13 shows the change in PFAS concentration (μg / g) with each process. These values ​​were calculated by subtracting the concentration in the non-regenerated GAC from the concentration in the regenerated GAC. Negative values ​​indicate a decrease in PFAS concentration. PFAS was totally removed in all runs except 6 and 7, indicating that the regeneration process used was able to remove PFAS from the industrial GAC. In runs 6 and 7, some of the detected PFAS compounds increased compared to the amount extracted from the control (6 had a large increase in PFOA and a small increase in PFBS, while 7 had a large increase in PFOA and an increase in PFNA and PFDA). In both of these runs, CaCl2 and NaAl(OH)4 were used. Run 2, which used Ca(OH)2 and Al2(SO4)3, performed the best among these regeneration methods, indicating that the use of Ca(OH)2 and Al2(SO4)3 improved performance. Since PFOA was frequently used in the laboratory, the increase in PFOA could have been the result of contamination.

[0247] [Table 13]

[0248] Table 14 shows the percent change in PFAS concentrations due to each process, calculated by dividing the change in concentration for each process by the initial concentration and then multiplying by 100. Overall, regeneration removed PFAS from GAC, with similar results for all compounds.

[0249] [Table 14]

[0250] Table 15 shows the average concentration change (μg / g) for each condition. Values ​​were calculated by averaging the concentration change due to regeneration for all runs using the conditions listed for each variable. Negative values ​​indicate the average PFAS removal for the particular conditions listed for each variable. Overall, PFAS were removed on average across all conditions, with only PFOA increasing in the CaCl2 condition.

[0251] [Table 15]

[0252] Table 16 shows the average percent concentration change for each condition. Values ​​were calculated by averaging the concentration change due to regeneration for all runs using the conditions listed for each variable, then multiplying by 100 and dividing by the non-regenerated concentration. Negative values ​​indicate the average PFAS removal for the particular conditions listed for each variable. Overall, PFAS were removed on average across all conditions, with only PFOA increasing slightly in the CaCl2 condition.

[0253] [Table 16]

[0254] Example 7: Regeneration and pretreatment on the column

[0255] Three columns loaded with GAC were prepared for breakthrough testing. The first column was loaded with GAC that had not been used previously ("fresh GAC"). The second column was loaded with GAC that had been saturated with PFAS / contaminants and regenerated ("used GAC"). The third column was loaded with GAC that had not been used but had been rinsed using a regeneration process ("pretreated GAC").

[0256] Materials: Calgon F400 GAC was used in this study. Spent GAC was used to capture pollutants in wastewater treatment plants until saturation. GAC was sieved through 60×80 mesh. A column was equipped with a carbon bed made from GAC. The flow rate was set at 2.9 mL / min. Column ID: 1 cm. Bed height: 3–3.2 cm. Bed weight: 1.1–1.15 g.

[0257] The pretreatment of fresh GAC was performed according to the following protocol: Take an Econo-Column and rinse with 50% ethanol and DI water. Rinse with DI water. Ensure that the bottom filter is intact. Fill the column with water and close the bottom valve. Pour 0.5 mm zirconia / silica beads into the bottom of the column, allowing the beads to spread 2-3 cm above the bottom filter. Tap gently to ensure that the beads are well packed, then open the valve at the bottom of the column and drain the water. Rinse the blender with ethanol and water and fill it with fresh F400 GAC. Blend the GAC and wet sieve it through ASTM 60 and 80 mesh sieves. Dry the 80 mesh sieve to obtain 60 x 80 mesh fresh F400. Add approximately 1.1 g of 60 x 80 mesh fresh F400 to the column (use a spatula rinsed with ethanol). The column height should be 3 cm. Use a syringe to push water up from the bottom of the column and tap to ensure the GAC is well packed. Continue tapping and flushing with water until no air bubbles remain. Push the water up to 2 cm above the GAC. Add enough 0.5 mm zirconia / silica beads to fill to 1-2 cm above the PAC. Tap gently to ensure the beads are well packed. Add a piece of damp glass wool on top of the zirconia / silica beads, then attach a flow adapter to hold the contents of the column in place. Pump DI water through the column and allow the F400 to wet for several hours. Pump 250 mL of 1 M NaOH fluid through the column at 2.8 mL / min, followed by 250 mL of 12% food grade H2O2. Next, 2.5 L of 20 g / l Al(OH)3 / 10 g / L NaOH fluid is pumped through the column at 2.9 mL / min, followed by 2.5 L of 4 g / L Ca(OH)2 solution in the same ratio. Next, 0.5 L of 0.1 M HCl solution is pumped through the column at 2.9 mL / min. Finally, 2.5 L of DI water is pumped through the column at 2.9 mL / min. The regeneration rinse (Al(OH)3, NaOH, and Ca(OH)2), HCl rinse, and DI water rinse are repeated. The amount of DI water in the final rinse is increased to 6 L.

[0258] Regeneration of spent GAC was performed following essentially the same protocol as the pretreatment protocol, except that the carbon was spent GAC rather than fresh GAC.

[0259] Approximately 20,000 BV of facility water was pumped through the columns of regenerated used GAC, fresh GAC, and pretreated GAC, and samples were taken every 1,000 BV (approximately 2500 mL).

[0260] FIG. 13 shows the performance of the regenerated GAC column compared to the fresh GAC column when PFOA was used as a representative PFAS compound.

[0261] The regenerated used GAC column is estimated to break through the regulatory limit (14 ppt) after 9650 BV of on-site water passes through the column. For the fresh GAC column, the breakthrough occurs after 12450 BV. Therefore, the recovery capacity is calculated to be 77%.

[0262] The Lab F400 and Fresh GAC columns were pretreated according to the regeneration process. The pretreated columns were loaded with approximately 20,000 BV of facility water and samples were taken every 1,000 BV.

[0263] FIG. 14 shows the performance of the F400 GAC column with pretreatment versus the F400 GAC column without pretreatment when using PFOA as a representative PFAS compound.

[0264] The pretreated column breaks through at approximately 7400 BV, while the untreated column showed breakthrough at 1150 BV. Due to differences in equipment, these results cannot be directly compared to the regeneration results in Figure 13.

[0265] Example 8: Regeneration with surfactants and flocculants

[0266] To determine whether emulsions of surfactants and flocculants benefit reclamation efficiency, 13 fluids were prepared as described in Table 17. Surfactants used included sodium dodecyl sulfate (SDS) and sorbitan monolaurate (Span® 20). Flocculants used included canola oil and safflower oil.

[0267] [Table 17]

[0268] Spent F400 GAC was ground in a blender that was rinsed with EtOH and deionized (DI) water. The ground GAC was then rinsed through ASTM 60 and 80 mesh sieves, dried in an oven at approximately 80° C., and collected in a centrifuge tube.

[0269] The nine test tubes and caps were rinsed with EtOH, followed by DI water and the tubes were dried. 0.5 g of the prepared 60×80 mesh GAC was added to each of eight clean 1 L Erlenmeyer flasks and one of the test tubes.

[0270] The specified amounts of fluids shown in Table 17 were added to a flask containing 60×80 mesh GAC in the order shown in Table 18. Each fluid was incubated on a shaker at 150 rpm for the time specified in Table 18. For NaOH, H2O2, soap, HCl, and DI water, plastic graduated cylinders were used for the measurements. Before the measurement, the soap was gently swirled to mix without forming bubbles. The regeneration mixtures (i.e., RM1-8) were shaken and poured into the flasks (i.e., all 500 mL of each regeneration mixture was poured into the flask). After rinse 10, another rinse was added, in which 200 mL of soap and 300 mL of DI water were added and incubated at 150 rpm for 18 hours (h).

[0271] [Table 18-1] [Table 18-2]

[0272] result:

[0273] The concentrations (μg / g) of PFAS extracted from each GAC are shown in Table 19. The mass of PFAS extracted from each sample was divided by the mass of GAC recovered from each run. The GAC remaining after each run was collected and placed in a test tube. PFAS were extracted from the GAC by incubating each with 10 mL of methanol at 25 rpm for 24 hours, followed by applying a 15-minute sonication. The PFAS extracted from the methanol were measured by LC-MS / MS. These values ​​are not corrected for extraction efficiency.

[0274] [Table 19]

[0275] The change in PFAS concentration (ug / g) due to each process is shown in Table 20. These values ​​were calculated by subtracting the concentrations in the non-regenerated GAC from the concentrations in the regenerated GAC. Negative values ​​indicate a decrease in PFAS concentration.

[0276] [Table 20-1]

[0277] PFAS were totally removed in all runs, indicating that the regeneration process used was able to remove PFAS from spent GAC.

[0278] The percent change in PFAS concentrations due to each process is shown in Table 21. The percent change was calculated by dividing the change in concentration for each process by the initial concentration and then multiplying by 100. Negative values ​​indicate a decrease in PFAS concentrations.

[0279] [Table 20-2]

[0280] The average percent concentration change (ug / g) for each condition is shown in Table 21. Values ​​were calculated by averaging the concentration change due to regeneration for all runs using the conditions listed for each variable, then multiplying by 100 and dividing by the non-regenerated concentration. Negative values ​​indicate the average removal of PFAS for the particular conditions listed for each variable.

[0281] [Table 21]

[0282] Example 9: Regeneration with surfactants and flocculants in columns

[0283] Spent F400 GAC was ground and packed into four commercial chromatography columns (2.5 cm diameter). Each column was subjected to a regeneration process as shown in Tables 22 and 23. Surfactants included SDS and PEG 300. Flocculants included ethyl octanoate and canola oil. Where indicated, the flocculant was positioned as an upstream layer in the column such that when the corresponding rinse circulated (or recirculated) through the column, the fluid (or recirculated fluid) contacted the flocculant before flowing through the column. In Rinse #4 for columns 3 and 4, the flocculant was included as a component of the rinse fluid.

[0284] [Table 22]

[0285] [Table 23]

[0286] While rinse #6 (i.e., water rinse) was running through each column, samples were periodically taken in a manner similar to that presented in Example 7. Specifically, computer-controlled sampling was achieved using an effluent outlet and an in-line sampling valve (commercially available from VICI). At regular intervals, the sample water was diverted into a sample bottle. Samples were analyzed according to Environmental Protection Agency (EPA) Method 533. Upon completion of rinse #6, each column was disassembled and the GAC was removed and separated from the inert glass beads (used to fill the space and support the carbon bed within the column). The separated GAC was then dried at low temperature in a vacuum oven and extracted with methanol, which was then analyzed.

[0287] result:

[0288] [Table 24]

[0289] [Table 25]

[0290] [Table 26]

[0291] [Table 27]

[0292] Other embodiments While the invention has been described in conjunction with its detailed description, it is to be understood that the foregoing description is illustrative and not limiting of the scope of the invention, which is defined by the appended claims. Other aspects, advantages, and modifications are within the scope of the following claims.

Claims

1. 1. A method for removing contaminants from an aqueous mixture, comprising: flowing a contaminated aqueous mixture containing one or more ionic contaminants into a vessel containing a carbon bed, wherein the one or more ionic contaminants are retained by the carbon bed; The one or more ionic contaminants retained by the carbon bed are treated with (a) hydroxides and / or peroxides, and (b) Ca. ２＋ , Mg ２＋ , Zn ２＋ , Sr ２＋ , Al ３＋ , B ３＋ , and Fe ３＋ with one or more cations selected from the contacting, wherein the (a) hydroxide and / or peroxide and the (b) one or more cations are provided in a single aqueous liquid or two or more separate aqueous liquids for contacting the one or more ionic contaminants; forming an aggregated contaminant phase comprising the one or more ionic contaminants; isolating said flocculated contaminant phase; Including, The method, wherein the one or more ionic contaminants comprise polyfluoroalkyl ions.

2. 10. The method of claim 1, wherein the aggregated contaminant phase is formed by precipitation, micelle formation, aggregation, flocculation, flotation, or emulsion breaking.

3. The method of claim 1 , wherein the (a) hydroxide and / or peroxide comprises sodium hydroxide, hydrogen peroxide and / or sodium peroxide.

4. The (b) one or more cations are Ca ２＋ The method of claim 1 , comprising:

5. The Ca ２＋ The method of claim 4, wherein is provided as calcium hydroxide.

6. The (b) one or more cations are Al ３＋ The method of claim 1 , comprising:

7. The Al ３＋ The method of claim 6, wherein is provided as aluminum sulfate, aluminum hydroxide, or sodium aluminate.

8. (a) the hydroxide and / or peroxide is provided in a first aqueous liquid; and (b) the one or more cations are provided in a second aqueous liquid; Optionally, the first aqueous liquid contacts the one or more ionic contaminants before the second aqueous liquid.

9. 10. The method of claim 1, further comprising rinsing the carbon bed with an acidic aqueous solution by flowing the solution through the vessel.

10. 10. The method of claim 9, wherein the aqueous acidic solution comprises hydrochloric acid, citric acid, sulfuric acid, nitric acid, or any combination and / or acid salt thereof.

11. The method of claim 1, further comprising rinsing the carbon bed with water by flowing water through the container, the water being, optionally, substantially free of additives, and optionally comprising repeating one or more of the steps of (i) contacting the ionic contaminants with the (a) hydroxides and / or peroxides, (ii) contacting the ionic contaminants with the (b) one or more cations, (iii) rinsing with the acidic aqueous solution, and (iv) rinsing with water.

12. The method further comprises treating the carbon bed with (a) hydroxides and / or peroxides, and (b) Ca, prior to flowing the contaminated aqueous mixture into the vessel. ２＋ , Mg ２＋ , Zn ２＋ , Sr ２＋ , Al ３＋ , B ３＋ , and Fe ３＋ 10. The method of claim 1, further comprising pretreating the carbon bed by contacting it with one or more cations selected from:

13. 13. The method of claim 12, wherein the pretreatment comprises rinsing the carbon bed with an acidic aqueous solution and rinsing the carbon bed with water.

14. 2. The method of claim 1, wherein the polyfluoroalkyl ion is perfluorooctanesulfonate or perfluorooctanoate.

15. The carbon bed comprises: (i) a powder, granule, bead, pellet, fabric, felt, nonwoven, or composite comprising a material selected from carbon, nitrogen-doped carbon, silicon-doped carbon, boron-doped carbon, charcoal, graphite, biochar, coke, carbon black, or any combination thereof; or (ii) activated charcoal powder, granules, pellets, beads, or any combination thereof; or (iii) activated carbon, or (iv) sintered carbon The method of claim 1 , comprising:

16. 10. The method of claim 1, wherein isolating the flocculated contaminant phase comprises filtration, nanofiltration, or sedimentation.

17. The method further comprising contacting the one or more ionic contaminants with a surfactant, the surfactant comprising: (i) a fatty acid, a sulfone, a phosphate, a polyether, a sulfate, a polyol, or any combination thereof; or (ii) sodium dodecyl sulfate (SDS), sorbitan monolaurate, polyethylene glycol (PEG), or any combination thereof The method of claim 1 , wherein the compound is selected from the group consisting of:

18. (i) before the (a) hydroxides and / or peroxides contact the one or more ionic contaminants, or (ii) after said (a) hydroxides and / or peroxides have contacted said one or more ionic contaminants; or (iii) while the (a) hydroxide and / or peroxide contacts the one or more ionic contaminants, 20. The method of claim 17, wherein the surfactant contacts the one or more ionic contaminants.

19. The method of claim 1, further comprising contacting the one or more ionic contaminants with a flocculant, the flocculant comprising an oil, a terpene, a fatty acid ester, or any combination thereof.

20. The oil is selected from coconut oil, corn oil, cottonseed oil, olive oil, palm oil, peanut oil, rapeseed oil, safflower oil, sesame oil, soybean oil, sunflower oil, or any combination thereof; the terpene is selected from myrcene, menthol, limonene, carvone, hinokitiol, linalool, or any combination thereof; 20. The method of claim 19, wherein the fatty acid ester is ethyl octanoate.

21. (i) before the (a) hydroxides and / or peroxides contact the one or more ionic contaminants, or (ii) after said (a) hydroxides and / or peroxides have contacted said one or more ionic contaminants; or (iii) while the (a) hydroxide and / or peroxide contacts the one or more ionic contaminants, 20. The method of claim 19, wherein the flocculant contacts the one or more ionic contaminants.

22. The method of claim 19, wherein the flocculant is provided as a layer of flocculant downstream of the vessel.

23. The method further comprising contacting the one or more ionic contaminants with an antifreeze; 10. The method of claim 1, wherein the antifreeze agent is selected from the group consisting of propylene glycol, polypropylene glycol, polyethylene glycol, glycerol, polyvinyl alcohol, carboxymethyl cellulose, ribose, sucrose, glucose, rhamnose, xylose, fructose, raffinose, stachyose, low molecular weight hydroxyethyl starch, maltodextrin, cellodextrin, and any combination thereof.

24. A method for regenerating a carbon bed, comprising: providing a container containing a carbon bed having one or more ionic contaminants retained thereon; contacting the one or more ionic contaminants retained by the carbon bed with (a) hydroxides and / or peroxides, and (b) one or more cations selected from Ca 2+ , Mg 2+ , Zn 2+ , Sr 2+ , Al 3+ , B 3+ , and Fe 3+ ; the contacting, wherein the (a) hydroxide and / or peroxide and the (b) one or more cations are provided in a single aqueous liquid or two or more separate aqueous liquids for contacting the one or more ionic contaminants; rinsing the carbon bed with an acidic aqueous solution by flowing the solution through the vessel; forming an aggregated contaminant phase comprising the one or more ionic contaminants; isolating said flocculated contaminant phase; Including, The method, wherein the one or more ionic contaminants comprise polyfluoroalkyl ions.

25. The method of claim 1, wherein the vessel is a pipe, a column, or a tank.

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