EP4168362A1 - Système pour élimination de contaminants pouvant être régénéré - Google Patents

Système pour élimination de contaminants pouvant être régénéré

Info

Publication number
EP4168362A1
EP4168362A1 EP21740390.6A EP21740390A EP4168362A1 EP 4168362 A1 EP4168362 A1 EP 4168362A1 EP 21740390 A EP21740390 A EP 21740390A EP 4168362 A1 EP4168362 A1 EP 4168362A1
Authority
EP
European Patent Office
Prior art keywords
capture
bed
capture bed
wash liquid
electrode
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP21740390.6A
Other languages
German (de)
English (en)
Inventor
George W. Adamson
Melissa Woodward
Cassidy Rae SCHNEIDER
Victoria L. KORN
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Ionic Water Technologies LLC
Original Assignee
Ionic Water Technologies LLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US16/904,706 external-priority patent/US11958763B2/en
Application filed by Ionic Water Technologies LLC filed Critical Ionic Water Technologies LLC
Publication of EP4168362A1 publication Critical patent/EP4168362A1/fr
Pending legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
    • C02F1/469—Treatment of water, waste water, or sewage by electrochemical methods by electrochemical separation, e.g. by electro-osmosis, electrodialysis, electrophoresis
    • C02F1/4691—Capacitive deionisation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/30—Processes for preparing, regenerating, or reactivating
    • B01J20/34—Regenerating or reactivating
    • B01J20/3416—Regenerating or reactivating of sorbents or filter aids comprising free carbon, e.g. activated carbon
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/30—Processes for preparing, regenerating, or reactivating
    • B01J20/34—Regenerating or reactivating
    • B01J20/3441—Regeneration or reactivation by electric current, ultrasound or irradiation, e.g. electromagnetic radiation such as X-rays, UV, light, microwaves
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/30—Processes for preparing, regenerating, or reactivating
    • B01J20/34—Regenerating or reactivating
    • B01J20/345—Regenerating or reactivating using a particular desorbing compound or mixture
    • B01J20/3475—Regenerating or reactivating using a particular desorbing compound or mixture in the liquid phase
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J47/00—Ion-exchange processes in general; Apparatus therefor
    • B01J47/02—Column or bed processes
    • B01J47/06—Column or bed processes during which the ion-exchange material is subjected to a physical treatment, e.g. heat, electric current, irradiation or vibration
    • B01J47/08—Column or bed processes during which the ion-exchange material is subjected to a physical treatment, e.g. heat, electric current, irradiation or vibration subjected to a direct electric current
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J49/00—Regeneration or reactivation of ion-exchangers; Apparatus therefor
    • B01J49/30—Electrical regeneration
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J49/00—Regeneration or reactivation of ion-exchangers; Apparatus therefor
    • B01J49/50—Regeneration or reactivation of ion-exchangers; Apparatus therefor characterised by the regeneration reagents
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/28—Treatment of water, waste water, or sewage by sorption
    • C02F1/283—Treatment of water, waste water, or sewage by sorption using coal, charred products, or inorganic mixtures containing them
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/42—Treatment of water, waste water, or sewage by ion-exchange
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/30—Organic compounds
    • C02F2101/36—Organic compounds containing halogen
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2303/00—Specific treatment goals
    • C02F2303/16—Regeneration of sorbents, filters

Definitions

  • the present invention relates to systems and methods for removing ionic contaminants from an aqueous mixture using a capture bed and for regenerating the capture bed for further use.
  • PFAS Per- and polyfluoroalkyl substances
  • a method of removing a contaminant from an aqueous mixture includes flowing a contaminated aqueous mixture comprising one or more ionic contaminants through a vessel that houses a capture bed and optionally an electrode in electrical contact with the capture bed.
  • the method also optionally includes applying a voltage to the electrode that is in electrical contact with the capture bed, such that the one or more ionic contaminants is bound to the capture bed.
  • the method further includes flowing an aqueous wash liquid through the vessel.
  • the method further optionally includes modulating the voltage applied to the electrode, such that the one or more ionic contaminants bound to the capture bed is released from the capture bed and is washed from the capture bed via the aqueous wash liquid.
  • the aqueous wash liquid may contain a counter ion that binds to the ionic contaminant forming an aggregate contaminant phase that can be removed from the aqueous wash liquid.
  • a system for removing a contaminant from water includes a separation vessel and disposed therein a capture bed, and optionally further includes: an electrode in electrical contact with the capture bed, and a power source electrically coupled to, and configured to apply a voltage to, the electrode that is in electrical contact with the capture bed.
  • the system also optionally includes a controller configured to control and modulate the voltage applied from the power source to the electrode.
  • the system further includes an intake line fluidly coupled to the vessel and configured to introduce a flow of a contaminated aqueous mixture to the vessel such that one or more ionic contaminants in the contaminated aqueous mixture binds to the capture bed, and a regeneration line fluidly coupled to the vessel and configured to introduce a flow of aqueous wash liquid to the vessel to wash ionic contaminant from the capture bed.
  • a method of regenerating a capture bed includes providing a vessel that houses a capture bed having one or more ionic contaminants bound to the capture bed, and optionally an electrode in electrical contact with the capture bed, and flowing an aqueous wash liquid through the vessel.
  • the method optionally further includes applying a voltage to the electrode, such that the one or more ionic contaminants bound to the capture bed is released from the capture bed and is washed from the capture bed via the aqueous wash liquid.
  • the aqueous wash liquid may contain a counter ion that binds to the ionic contaminant forming an aggregate contaminant phase that can be removed from the aqueous wash liquid.
  • a system for regenerating a capture bed includes a capture bed housed within a separation vessel, and optionally further includes: an electrode in electrical contact with the capture bed and a power source electrically coupled to, and configured to apply a voltage to the electrode.
  • the system also optionally includes a controller configured to control and modulate the voltage applied from the power source to the electrode.
  • the system further includes a regeneration line fluidly coupled to the separation vessel and configured to introduce a flow of aqueous wash liquid to the separation vessel to wash ionic contaminant from the capture bed.
  • FIG. 1 is an illustration of a capture system for removing contaminants from water according to an embodiment of the invention.
  • FIGs. 2A and 2B are a schematic of a capture system (2A) and regeneration system (2B) according to another embodiment of the invention.
  • FIG. 3 is a process diagram of an integrated capture and regeneration system according to another embodiment of the invention.
  • FIG. 4 is a flow chart showing the steps of Example 1.
  • FIG. 5 shows the visual appearance of the carbon substrate of Example 1.
  • FIG. 6 is a chart showing PFNA absorption by a fresh carbon bed from a mixed contaminant sample.
  • FIG. 7 is a chart showing PFNA absorption by a regenerated carbon bed from a mixed contaminant sample.
  • FIG. 8 is a chart showing PFOA absorption by a fresh carbon bed from a mixed contaminant sample.
  • FIG. 9 is a chart showing PFOA absorption by a regenerated carbon bed from a mixed contaminant sample.
  • FIG. 10 is a chart showing PFOS absorption by a fresh carbon bed from a mixed contaminant sample.
  • FIG. 11 is a chart showing PFOS absorption by a regenerated carbon bed from a mixed contaminant sample.
  • FIG. 12 is a chart showing the concentration of PFOA in filtrate collected after flow through a carbon bed in a column.
  • first, second, third, etc. may be used herein 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 be only 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 a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example configurations.
  • Electrode refers to a solid electric conductor that carries electric current to another element, such as a capture bed.
  • activated carbon refers to a form of carbon processed to have small pores that increase the available surface area.
  • polyfluoroalkyl ion refers an ionic compound comprising an alkyl chain with multiple fluoro substitutions, which is optionally further substituted, such as with ether, alcohol, amine (including substituted amine), and carboxylic acid groups.
  • Per- and polyfluoroalkyl substance includes but is not limited to the following substances: perfluorobutanoic acid, perfluoropentanoic acid, perfluorohexanoic acid, perfluoroheptanoic acid, perfluorooctanoic acid, perfluorononanoic acid, perfluorodecanoic acid, perfluoroundecanoic acid, perfluorododecanoic acid, perfluorotridecanoic acid, perfluorotetradecanoic acid, perfluorohexadecanoic acid, perfluorooctadecanoic acid, perfluorobutanesulfonic acid, perfluoropentanesulfonic acid, perfluorohexanesulfonic acid, perfluorooctanesulfonic acid, perfluorononanesulfonic acid, perfluorodecanesulfonic acid, perfluorod
  • PFAS 9-chlorohexadecafluoro-2-oxanone-l -sulfonic acid.
  • PFAS also includes partial fluorinations.
  • the conjugate bases of these acids are examples of polyfluoroalkyl ions.
  • Capturing PFAS includes capturing a conjugate base of a PFAS.
  • PFOS refers to perfluorooctanesulfonic acid. Capturing/releasing PFOS includes capturing/releasing its conjugate base, perfluorooctanesulfonate.
  • PFOA perfluorooctanoic acid. Capturing/releasing PFO A includes capturing/releasing its conjugate base, perfluorooctanoate.
  • a system for regenerating a capture bed or a "regeneration system.”
  • Regenerating refers to removing ionic contaminant from the capture bed, i.e., contaminant that was bound to the capture bed during a water purification process.
  • Systems and methods for capturing ionic contaminants on a capture bed, and thereby removing them from an aqueous mixture are described herein. As more ionic contaminants are bound to the capture bed the bed becomes less effective at removing the ionic contaminants. Eventually, the contaminants must be released from the capture bed or the capture bed itself must be replaced. Regenerating the capture bed in situ by releasing the bound ionic contaminants allows for continued use of the capture bed without costly replacement and environmentally harmful disposal of the spent capture bed.
  • the system for regenerating a capture bed includes a capture bed that is housed within a separation vessel.
  • the system may be an electrified system with an electrode in electrical contact with a capture bed that is housed within a separation vessel; a power source electrically coupled to, and configured to apply a voltage to the electrode; and a controller configured to control and modulate the voltage applied from the power source to the electrode.
  • the regeneration system is able to apply voltage to the capture bed that drives the release of ionic contaminant from the capture bed.
  • the electrode comprises graphite, titanium, stainless steel, cast iron, a conductive metal oxide, a conductive diamond, a titanium suboxide, titanium nitride, titanium carbide, titanium boride, a doped manganese oxide, or mixtures or composites thereof.
  • the system for regenerating a capture bed also includes a regeneration line fluidly coupled to the separation vessel and configured to introduce a flow of aqueous wash liquid to the separation vessel to wash ionic contaminant from the capture bed. The application of voltage to the electrode together with flow of wash liquid to the capture bed via the regeneration line drives the release of ionic contaminant from the capture bed, resulting in regeneration of the capture bed for further use.
  • the regeneration line is fluidly coupled to a regeneration line pump and/or a regeneration line valve to control the flow of wash liquid supplied to the separation vessel.
  • the regeneration system includes a flow controller (e.g., a PLC controller) to control the regeneration line pump and/or regeneration line valve.
  • the regeneration system is a sub-system of an integrated capture and regeneration system. Such integrated systems are described below. Integrated systems can be installed at a site as a stand-alone system for providing purified water. Alternatively, the regeneration system may be an add-on system to an existing capture system. For example, there are existing systems for water purification with capture beds, e.g., carbon beds or ion exchange resin beds; the regeneration systems described herein may be installed as an add-on system to provide for in situ regeneration of an existing water purification system. In some embodiments, the regeneration system allows for continued use of the capture bed in the existing system by release, sequestration, and removal of the ionic contaminants in the capture bed.
  • capture beds e.g., carbon beds or ion exchange resin beds
  • the regeneration systems described herein may be installed as an add-on system to provide for in situ regeneration of an existing water purification system.
  • the regeneration system allows for continued use of the capture bed in the existing system by release, sequestration, and removal of the ionic contaminants in the capture bed.
  • the following embodiments describe an exemplary installation of an electrified regeneration system onto an existing capture system.
  • the electrodes are installed by insertion into the existing capture bed, and hooked up to the power source controlled by the controller.
  • a regeneration line is fitted onto the existing piping of the capture system (or directly onto the separation vessel) to add separate inlet and outlet flow of wash liquid into the separation vessel.
  • Valves e.g., control valves, are installed to control and switch the source of flow into the separation vessel between (1) an aqueous mixture to be purified (during a capture cycle) and (2) a wash liquid to regenerate the capture bed.
  • the regeneration system includes concentration and removal of the ionic contaminant released from the capture bed.
  • a contaminant sequestration agent is employed that can more efficiently be removed from the system than removal of the capture bed.
  • the sequestration agent is more environmentally friendly to dispose of than disposal of a spent carbon bed or spent ion exchange resin bed (i.e., with bound contaminant).
  • the sequestration agent is a counter ion in the wash liquid configured to bind to the ionic contaminant to form an aggregate contaminant phase. Suitable sequestration agents and counter ions are described below.
  • the system further includes a filter configured to remove the aggregate contaminant phase from the wash liquid. Since the aggregate contaminant phase is sparingly soluble to insoluble in the water phase, the precipitate tends to form a distinct solid or liquid phase that is large enough to either float or sink or be captured in a particulate filter.
  • a skimmer can be used to capture the aggregate contaminant phase.
  • the regeneration system further comprises a regeneration vessel that houses a stationary ion source configured to bind the one or more ionic contaminants in the aqueous wash liquid, wherein the regeneration vessel is fluidly coupled to the separation vessel.
  • the stationary ion source comprises lime, e.g., a plurality of slaked lime pellets.
  • the stationary ion source is an alkaline metal coated surface where the surface electrostatically or by dispersion forces reversibly holds the alkaline element until a contaminant can form a precipitate. The contaminant is held at the surface until the surface binding is reversed (e.g., reversing polarity of electrodes).
  • the regeneration system further comprises a sequestration agent vessel comprising a sequestration agent in a liquid media.
  • the regeneration system further comprises a mixing tank for mixing the sequestration agent with the wash liquid and optionally a settler apparatus for collecting solids precipitated from the liquid in the mixing tank.
  • a filter is fluidly coupled to the mixing tank for filtering solids from the mixing tank, for example, solids that were not separated in the settler apparatus.
  • the aqueous wash liquid comprises untreated contaminated aqueous mixture.
  • the aqueous wash liquid comprises a C1-5 alcohol.
  • the aqueous wash liquid further comprises an antifreeze agent that lowers the freezing point of the aqueous wash liquid.
  • the antifreeze agent is selected from the group consisting of propylene glycol, polypropylene glycol, polyethylene glycol, glycerol, polyvinyl alcohol, carboxymethylcellulose, ribose, sucrose, glucose, rhamnose, xylose, fructose, raffmose, stachyose, low molecular weight hydroxyethyl starches, maltodextrin, cellodextrins, and any mixture thereof.
  • the aqueous wash liquid comprises from about 0.1 wt% to about 20 wt% of the antifreeze agent (e.g., about 1 to about 10 wt% of the antifreeze agent).
  • the freezing point of the aqueous wash liquid is below about -0.3 °C.
  • the antifreeze agent encourages slush formation of the aqueous wash liquid at freezing temperatures.
  • the aqueous wash liquid further comprises one or more additives for cleaning the capture bed of scale and/or inorganic precipitate.
  • Inorganic precipitate may comprise, for example, iron or manganese.
  • 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), a water-soluble fatty acid, a salt of the aforementioned acids (e.g., a sodium or potassium salt), and any mixture thereof.
  • the acid is configured to solubilize inorganic precipitates or scale on the capture bed, e.g., at or near the leading edge of the capture bed.
  • the pH of the aqueous wash liquid with the additive(s) is from about 0 to about 6. In some embodiments, the pH of the aqueous wash liquid with the additive(s) is from about 3 to about 6. In some embodiments, the concentration of the additive(s) in the aqueous wash liquid is from about 0.1 wt% to about 15 wt%, or up to the limit of solubility of the acid in the wash liquid.
  • the system further comprises a second wash liquid that can be used to rinse the capture bed before, after, or simultaneously with the aqueous wash liquid; the second wash liquid may be referred to as a “rinse liquid.”
  • the rinse liquid may be introduced to the vessel via a rinse liquid line.
  • the rinse liquid is an aqueous liquid comprising one or more additives for cleaning the capture bed of scale and/or inorganic precipitate.
  • 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), a water-soluble fatty acid, a salt of the aforementioned acids (e.g., a sodium or potassium salt), and any mixture thereof.
  • the pH of the rinse liquid is from about 3 to about 6.
  • the concentration of the additive(s) in the rinse liquid is from about 0.1 wt% to about 15 wt%, or up to the limit of solubility of the acid in the rinse liquid.
  • FIG. 2 is a schematic for an exemplary system 200 according to another embodiment of the present invention.
  • FIG. 2A shows a capture system 200a in use for capturing contaminants, specifically PFOA and/or PFOS, from a water source, which is described in detail below.
  • FIG. 2B shows a regeneration system 200b.
  • the regeneration system as schematically shown 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 comprising wash liquid ("container of waste solution”) is fluidly coupled via a regeneration line 222 to the separation vessel 202 that houses the capture bed, specifically a capture bed stack 204 ("cell stack”) and is configured to flow wash liquid through the separation vessel 202.
  • a regeneration outlet line 224 is fluidly coupled to the opposite end of the separation vessel.
  • a valve 218b controls flow out of the separation vessel via the regeneration outlet line 224.
  • the regeneration outlet line 224 is fluidly coupled to the regeneration vessel 220 thus completing the circulation loop.
  • the system 200b is configured to recirculate the wash liquid through the separation vessel 202 multiple times resulting in a wash liquid with high concentration of contaminant (e.g., PFOA/PFOS).
  • the regeneration vessel 220 contains a stationary ion source 226, which are slaked lime pellets as shown in this embodiment.
  • the slaked lime pellets 226 are configured to bind to the PFOA/PFOS in the regeneration vessel 220. Slaked lime pellets 226 can easily be removed from the system for disposal. Disposal of slaked lime pellets is more economical and environmentally friendly than disposal of an activated carbon bed or ion exchange resin bed.
  • the method of regenerating a capture bed includes providing a vessel that houses a capture bed having one or more ionic contaminants bound to the capture bed, and optionally an electrode in electrical contact with the capture bed.
  • the vessel may be part of an integrated capture and regeneration system that includes a system for capturing a contaminant, as described below.
  • the vessel may be part of an existing contaminant capture system (water purification system), wherein the regeneration method is performed on the existing vessel/capture system by installing a regeneration system (as described above) onto the existing vessel/capture system.
  • the method of regenerating a capture bed further includes flowing an aqueous wash liquid through the vessel and optionally applying a voltage to the electrode, such that the one or more ionic contaminants bound to the capture bed is released from the capture bed and washed from the bed via the aqueous wash liquid.
  • the aqueous wash liquid is flowed into the separation vessel at a rate of from about 5 to about 400 liters per minute per square meter of capture bed to release bound ionic contaminant from the capture bed and wash the release ionic contaminant out of the capture bed.
  • a voltage is applied to the electrode.
  • a voltage having a positive polarity of from about 0.01 V to about 1.5 V e.g., about 0.01 V to about 1.2 V
  • a voltage having a negative polarity of from about -0.01 V to about -1.6 V is applied to the electrode in order to drive the release of the ionic contaminant.
  • an AC voltage is applied, optionally with a DC offset, to drive release of the ionic contaminant. In some embodiments, no voltage is applied.
  • the wash liquid comprises a sequestration agent.
  • the sequestration agent is a counter ion.
  • the counter ion is a cation selected from Ca 2+ , Mg 2+ , Zn 2+ , Sr 2+ , Al 3+ , B 3+ , Al 3+ , or Fe 3+ . Cations are suitable for use in regenerating a capture bed with a bound anionic contaminant, such as perfluoroalkyl anions, or phosphate or borate contaminants.
  • the counter ion is Ca 2+ .
  • the counter ion is Al 3+ .
  • the counter ion is supplied to the wash liquid by addition of calcium hydroxide, calcium oxide, or calcium chloride to the wash liquid.
  • the wash liquid is basic and the source of Ca 2+ is calcium hydroxide.
  • the wash liquid is acidic and the source of Ca 2+ is calcium chloride.
  • the counter ion is supplied to the wash liquid by addition of aluminum hydroxide.
  • the counter ion is supplied to the wash liquid by addition of a mixture of aluminum hydroxide and sodium hydroxide.
  • the counter ion is supplied to the wash liquid by addition of NaAl(OH)4 sodium aluminate.
  • the pH of the aqueous wash liquid is modulated to cause the aggregate contaminant phase to precipitate from the aqueous wash liquid.
  • lime or other hydroxide can be added to the aqueous wash liquid to change the pH.
  • Sodium hydroxide, carbon dioxide, bicarbonate, phosphoric acid, and sulfuric acid may also be used as pH modulating agents.
  • the pH is modulated distal to (i.e., downstream of) the capture bed.
  • pH modulation may be accomplished with a lime wash of the column by bubbling carbon dioxide or adding bicarbonate in another tank upstream of the capture bed; this lowers the pH from the Ca(OH)2 solution to a neutral or near neutral pH and improves the aggregate size of the precipitate by co-precipitating calcium carbonate with the perfluoroalkyl compounds.
  • phosphoric acid and sulfuric acid may also be introduced to form salts with calcium and act as neutralizing agents.
  • the wash liquid comprises sodium hydroxide.
  • the counter ion is an anion selected from a phosphate, a sulfate, or a borate.
  • Anions are suitable for use in regenerating a capture bed with a bound cationic contaminant, such as perfluoroalkyl cations.
  • the counter ion is supplied to the wash liquid by addition of calcium phosphate, calcium borate, calcium sulphate, magnesium phosphate, magnesium borate, or magnesium sulphate to the wash liquid.
  • perfluoroalkyl compounds may be nonionic and must first be partially decomposed before they can be released using the counter ion.
  • the regeneration method further comprises partially decomposing the nonionic perfluoroalkyl compound(s), such as by chemical, photochemical, electrochemical decomposition or by application of DC or AC electrical discharge.
  • the sequestration agent and the released ionic contaminant upon flowing the wash liquid comprising the sequestration agent through the separation vessel, the sequestration agent and the released ionic contaminant form an aggregate contaminant phase.
  • the aggregate contaminant phase separates from the aqueous wash liquid by precipitation.
  • the aggregate contaminant phase forms a foam.
  • the aggregate contaminant phase forms a dispersed phase within the aqueous wash liquid.
  • the aqueous wash liquid is at least substantially saturated with the ionic contaminant upon exiting the capture bed.
  • the regeneration method comprises adding a sequestration agent to the wash liquid.
  • a sequestration agent vessel is provided containing the sequestration agent in liquid media (e.g., aqueous media) and the sequestration agent is flowed from the sequestration agent vessel to be added to the wash liquid. The flow may be controlled by a pump and/or valve.
  • the sequestration agent is mixed with the wash liquid, for example in a mixing tank.
  • the wash liquid mixed with the sequestration agent is wash liquid that is substantially saturated with the ionic contaminant.
  • a rinse liquid comprising additive(s), as described above, is flowed through the vessel and the capture bed.
  • the rinse liquid may be used before, after, or simultaneously with the aqueous wash liquid.
  • the method further comprises removing, and optionally solubilizing, inorganic precipitates or scale on the capture bed, e.g., at or near the leading edge of the capture bed.
  • the regeneration method further comprises contacting the released ionic contaminant in the aqueous wash liquid with a stationary ion source, such that the ionic contaminant is bound to the stationary ion source forming an aggregate contaminant phase.
  • the regeneration method further comprises removal of the aggregate contaminant phase.
  • removal of the aggregate contaminant phase comprises filtering the aggregate contaminant phase from the wash liquid.
  • the regeneration method further comprises disposal of the removed aggregate contaminant phase, e.g., to a landfill.
  • the aggregate contaminant phase may also be destroyed, e.g., by calcination, thermal decomposition, or vitrification.
  • the regeneration method further comprises electrochemical oxidation of the wash liquid.
  • the regeneration method further comprises pre-oxidizing the ionic contaminant comprising converting alcohol groups of the ionic contaminant to carboxylic acid groups by chemical or electrochemical means.
  • the ionic contaminant comprises an organic end with an ionic moiety.
  • the ionic contaminant is selected from the group consisting of a polyfluoroalkyl ion, a borate, a phosphate, a polyphosphate, a sulfate, an organic acid, a fatty acid, a humic substance, a shortchain PFAS, a water-soluble medication, a detergent, a water- soluble insecticide, a water-soluble fungicide, a water-soluble germicide, and any combination thereof.
  • the ionic contaminant is a polyfluoroalkyl ion.
  • the polyfluoroalkyl ion is perfluorooctanesulfonate or perfluorooctanoate.
  • Perfluorooctanesulfonate is the conjugate base of perfluorooctanesulfonic acid (PFOS).
  • Perfluorooctanoate is the conjugate base of perfluorooctanoic acid (PFOA).
  • the polyfluoroalkyl ion is perfluorobutanesulfonate or perfluorobutanoate.
  • Perfluorobutanesulfonate is the conjugate base of perfluorobutanesulfonic acid (PFBS).
  • Perfluorobutanoate is the conjugate base of perfluorobutanoic acid (PFBA).
  • FIG. 2B The system of FIG. 2B can also be described in terms of a regeneration method of which it illustrates.
  • Wash liquid (“waste solution”) is flowed to a separation vessel that houses a capture bed (“cell stack”) and flows through the vessel. Ionic contaminants bound to the cell stack are released as wash liquid flows through the vessel and voltage is applied (not shown) to the cell stack.
  • a valve (“waste water valve”) is opened to direct flow of wash liquid with released ionic contaminant (PFOA and/or PFOS) to a regeneration vessel ("container of waste solution”) via a regeneration outlet line.
  • a stationary ion source slaked lime pellets in this embodiment
  • slaked lime pellets with bound PFOA/PFOS can be removed from the system and disposed of.
  • the capture system includes a separation vessel that houses a capture bed configured to capture ionic contaminants in an aqueous mixture flowed through the separation vessel.
  • the system also provides for regeneration of the capture bed as an integrated capture and regeneration system, or an "integrated system.”
  • the integrated system may include any of the features of a regeneration system and/or capture system as described herein.
  • the capture system includes: a separation vessel and disposed therein a capture bed; and an intake line fluidly coupled to the vessel and configured to introduce a flow of a contaminated aqueous mixture to the vessel such that one or more ionic contaminants in the contaminated aqueous mixture binds to the capture bed; and optionally further includes an electrode in electrical contact with the capture bed, a power source electrically coupled to, and configured to apply a voltage to, the electrode that is in electrical contact with the capture bed, and a controller configured to control and modulate the voltage applied from the power source to the electrode.
  • the integrated capture and regeneration system includes a capture system and further includes a regeneration line fluidly coupled to the vessel and configured to introduce a flow of aqueous wash liquid to the vessel to wash ionic contaminant from the capture bed.
  • the capture system further includes a pump fluidly coupled to the intake line and configured to pump the contaminated aqueous mixture into the separation vessel. In some embodiments, the capture system further includes a valve fluidly coupled to the intake line and configured to control the flow of the contaminated aqueous mixture into the separation vessel.
  • the system is a non-electrified system.
  • the system is an electrified system with an electrode, power source, and controller as described herein.
  • the controller is configured to reduce or reverse the current applied from the power source.
  • the controller is further configured to reduce the voltage applied to the electrode, reverse the polarity of the voltage applied to the electrode, terminate the voltage applied to the electrode, or any combination thereof.
  • the power source is configured to apply a first voltage to the electrode during flow of contaminated aqueous mixture to capture bed (during a capture cycle). During flow of wash liquid to the capture bed (during a regeneration cycle), terminating, reducing or reversing the current helps to drive the release of the bound contaminant from the capture bed.
  • the capture bed e.g., activated carbon bed
  • the capture bed is surface-modified with functional groups 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.
  • the capture bed is at least partially conductive. In some embodiments, the capture bed is porous. In some embodiments, the capture bed is an activated carbon bed. In some embodiments, the capture bed is an ion exchange resin bed. In some embodiments, the capture bed is a composite of activated carbon and ion exchange resin. In some embodiments, the capture bed is an activated carbon metal oxide composite. In some embodiments, the capture bed is a FILTRASORB® activated carbon bed from Calgon Carbon.
  • the capture bed comprises black pearls 200 (activated graphite) from Cabot corporation. In some embodiments, the capture bed comprises PBX51 (activated graphite) from Cabot corporation.
  • the capture bed comprises powder, granules, beads, pellets, cloths, felts, nonwoven fabrics, or composites comprising a material selected from carbon, nitrogen- doped carbon, boron-doped carbon, charcoal, graphite, biochar, coke, carbon black, or any combination thereof.
  • the capture bed comprises activated charcoal powder, granules, pellets, beads, or any combination thereof.
  • the capture bed comprises activated carbon having an average surface area of from about 100 m 2 /g to about 2000 m 2 /g. In some embodiments, the capture bed has a conductivity of from about 0.01 S/cm to about 100 S/cm. In some embodiments, the capture bed has a porosity of from about 30% to about 95%.
  • the capture bed is surface-modified with functional groups 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.
  • the capture bed has an ionic complexing species bound to it.
  • the ionic complexing species is Ca 2+ ,Mg 2+ , Al 3+ , phosphate, borate, or silicate.
  • the ionic complexing species is an alkaline ion mixed with fatty acid or wax.
  • the capture bed further comprises a binder dispersed in the capture bed.
  • the binder comprises a wax, a starch, a sugar, a polysaccharide, or any combination thereof.
  • the wax is a polyethylene wax.
  • the wax is camauba wax.
  • the capture bed is disposed longitudinally along the flow axis of the separation vessel such that the contaminated aqueous mixture flows by the capture bed. In other embodiments, the capture bed is disposed laterally across the separation vessel such that the water flows through the capture bed.
  • the capture bed is adjacent to a separator. In some embodiments, the capture bed is wrapped in a separator, enclosed within a separator, or sandwiched between two separators.
  • the capture system further comprises a second separation vessel that houses a second capture bed and a second electrode in electrical contact with the second capture bed.
  • the power source or a second power source is configured to apply a voltage to the second electrode that is in electrical contact with the second capture bed.
  • the separation vessel further houses a second capture bed and a second electrode in electrical contact with the second capture bed.
  • the second capture bed is adjacent to the first capture bed with a separator disposed between the first and second capture beds.
  • the separator is disposed around the first and second capture beds in a Z-fold, S-fold, or C-fold arrangement.
  • the separator is disposed around one or more capture beds in a spiral wound or jelly roll configuration.
  • 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.
  • the separation vessel comprises a stack comprising a plurality of capture beds.
  • the plurality of capture beds in the stack are separated from each other by one or more separators.
  • the plurality of capture beds are in electrical contact with the first or second electrode.
  • the power source is configured to apply a positive voltage to the first electrode, wherein the first electrode is in electrical contact with a first plurality of capture beds, and wherein the power source is configured to apply a negative voltage to the second electrode, wherein the second electrode is in electrical contact with a second plurality of capture beds.
  • the first plurality of capture beds are stacked in an alternating fashion with the second plurality of capture beds.
  • the vessel is a pipe, column, or tank.
  • the separator comprises a porous plastic.
  • the porous plastic is a plastic mesh.
  • the separator comprises an inert material. Suitable materials for the separator include nylon, polyamide, polypropylene, and HDPE.
  • FIG. 1 illustrates an exemplary capture system according to an embodiment of the present invention.
  • a separation vessel or column 102 e.g., PVC pipe
  • the stack 104 is arranged with each carbon powder capture bed 104a-d wrapped in a non-woven separator 106a-d. Stacks can be added, and the column 102 lengthened, to fit the desired amount of carbon.
  • the stack 104 is configured with the wrapped carbon power capture beds 104a-d disposed laterally across the vessel 102 such that flow through the vessel 102 will flow through each capture bed 104a-d of the stack 104.
  • Electrodes 108 made of graphite filled polymer are in electrical contact with the carbon powder capture beds 104a-d.
  • the electrodes 108 are electrically coupled to a power source 150
  • a first electrode 108a is inserted longitudinally through the stack 104 and is in electrical contact with a first 104a and third 104c capture bed of the stack, but is electrically insulated from a second 104b and fourth 104d capture bed of the stack.
  • Non-conductive tape 110 is wrapped around a portion of the first electrode 108a in its electrically insulated areas in the second and fourth capture bed.
  • a second electrode 108b is inserted longitudinally (and separated from the first electrode 108a) through the stack 104 and is in electrical contact with the second 104b and fourth 104d capture bed of the stack, but is electrically insulated from the first 104a and third 104c capture bed.
  • Non-conductive tape 110 is wrapped around a portion of the second electrode 108b in its electrically insulated areas in the first 104a and third 104c capture bed.
  • An intake line 112 is fluidly coupled to a first end of the separation vessel 102 and an outlet line 116 is fluidly coupled 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.
  • FIG. 2 is a schematic for exemplary system 200 according to another embodiment of the present invention.
  • FIG. 2A shows a capture system 200a in use for capturing contaminants, specifically PFOA or PFOS, from a water source.
  • An intake line 212 is fluidly coupled to a vessel 202 that houses a cell stack 204 and configured to supply water in need of treatment due to high concentration of PFOA and/or PFOS (e.g., having levels PFOA and/or PFOS above the upper limit as defined by EPA or other regulatory body) into the vessel 202.
  • the cell stack 204 comprises capture beds in a stack, optionally with separator between the beds.
  • An outlet has valves 218a, 218b for a clean water outlet and a waste water (i.e. wash liquid) outlet.
  • FIG. 2B shows a regeneration system 200b as described above. The regeneration system of FIG. 2B may be installed together with the system of FIG. 2A as part of an integrated system.
  • FIG. 3 is a process diagram for an exemplary integrated system 300 according to another embodiment of the present invention.
  • a raw water tank 308 contains the contaminated aqueous mixture in need of ionic contaminant removal.
  • the raw water tank 308 is fluidly coupled to a pump 314 ("pump 1 ") with an intervening valve 312 to control flow.
  • Pump 1 314 is fluidly coupled to the inlet 316 of a separation vessel 302 (e.g., an activated carbon EDI filtration column) that houses activated carbon capture beds 304.
  • a voltage/current source 306 is electrically coupled to the capture beds 304 of the separation vessel 302.
  • the outlet 318 of the column 302 is fluidly coupled to a clean water tank 324 with an intervening valve 322.
  • the intervening valve 322 is also fluidly coupled to the raw water tank 308 via recirculation line 326 providing for optional recirculation of the liquid for one or more additional cycles of contaminant removal.
  • the raw water tank 308 is also fluidly coupled to another pump 330 ("pump 2") via the same intervening valve 312 that controls flow into pump 1 314.
  • Pump 2330 is fluidly coupled to a second separation vessel 332 (an activated graphite EDI concentrating column) that houses an activated graphite capture bed 334.
  • a voltage/current 336 source is electrically coupled to the activated graphite bed 334.
  • the second separation vessel 332 is fluidly coupled to the clean water tank 308 and to the recirculation valve 322.
  • a regeneration vessel 328 (waste water tank) containing wash liquid is fluidly coupled to both Pump 1 314 and Pump 2330 and both separation vessels 302, 332.
  • the wash liquid upon flowing through the capture beds 304 and/or 334 can be referred to as extract and is fluidly coupled to a precipitator 338.
  • the precipitator 338 is also fluidly coupled to a regeneration fluid tank 340 via another pump 342 ("Pump 3").
  • the regeneration fluid tank 340 contains a counter ion in a liquid media.
  • the precipitator 338 is fluidly coupled to a settler 344 for removing precipitated solids from the extract upon mixing with the counter ion.
  • the settler 344 is also fluidly coupled to a filter 346 for further removal of solids from the liquid phase exiting the settler.
  • the system 300 can be controlled by a PLC controller 348.
  • the capture method includes flowing an aqueous mixture comprising one or more ionic contaminants through a separation vessel that houses a capture bed in order to bind the one or more ionic contaminants to the capture bed, thereby removing the one or more ionic contaminants from the aqueous mixture.
  • the method includes regeneration of the capture bed as part of an integrated capture and regeneration method, or an "integrated method.”
  • the capture method further includes applying a voltage to the electrode that is in electrical contact with the capture bed, such that the one or more ionic contaminants is bound to the capture bed. The applied voltage enhances the binding of the one or more ionic contaminants to the capture bed. Methods with application of voltage are referred to as electrified methods.
  • the integrated method further includes a regeneration cycle comprising flowing an aqueous wash liquid through the separation vessel and optionally, in electrified methods, modulating the voltage applied to the electrode, such that the one or more ionic contaminants bound to the capture bed is released from the capture bed and is washed from the capture bed via the aqueous wash liquid.
  • the modulated voltage helps to drive the release of the bound ionic contaminant from the capture bed.
  • the integrated method specifically the regeneration cycle thereof, may include any of the steps and features of the regeneration method described above.
  • applying the voltage to the electrode comprises running an electrical current to the electrode
  • modulating the voltage comprises reducing or reversing the electrical current running to the electrode.
  • the voltage applied to the electrode during capture of contaminants has a positive polarity from about 0.01 V to about 2.2 V. In some embodiments, the voltage applied to the electrode during capture of contaminants has a positive polarity from about 0.01 V to about 1.6 V. In some embodiments, modulating the voltage to release the ionic contaminant comprises reducing the electric current to generate a modulated voltage having a positive polarity of from about 0.01 V to about 1.5 V (e.g., about 0.01 V to about 1.2 V).
  • modulating the voltage to release the ionic contaminant comprises reversing the electric current to generate a modulated voltage having a negative polarity of from about -0.01 V to about -2.2V or from about -0.01 V to about - 1.6 V. In some embodiments, modulating the voltage to release the ionic contaminant comprises applying an AC voltage optionally with a DC offset.
  • the contaminated aqueous mixture is flowed into the vessel at a rate from 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 from 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 from about 0.01 to about 10 liters per minute per kilogram of capture bed. In some embodiments, the capture bed has a mass of from about 4,000 to about 10,000 kilograms. In some embodiments, the pressure drop across the capture bed is from about 1 psi to about 200 psi.
  • the aqueous wash liquid is flowed into the vessel at a rate from about 5 to about 400 liters per minute per square meter of capture bed. In some embodiments, the aqueous wash liquid is flowed into the vessel at a rate from about 80 to about 240 liters per minute per square meter of capture bed. In some embodiments, the aqueous wash liquid is flowed into the vessel at a rate from about 0.01 to about 10 liters per minute per kilogram of capture bed.
  • the capture method further comprises binding an ionic complexing species to the capture bed prior to flowing the contaminated aqueous mixture through the vessel, such that upon flowing the contaminated aqueous mixture through the vessel, the ionic contaminant binds to the capture bed by forming a complex with the ionic complexing species wherein the complex is bound to the capture bed.
  • the ionic complexing species is Ca 2+ , Mg 2+ , phosphate, borate, or silicate.
  • the ionic complexing species is an alkaline ion mixed with fatty acid or wax.
  • the capture bed is situated in the vessel such that the contaminated aqueous mixture flows by the capture bed. In some embodiments, the capture bed is situated in the vessel such that the contaminated aqueous mixture flows through the capture bed.
  • the capture method further includes flowing the contaminated aqueous mixture through a second vessel that houses a second capture bed and a second electrode in electrical contact with the second capture bed and applying a voltage to the second electrode that is in electrical contact with the second capture bed.
  • the vessel further houses a second capture bed and a second electrode in electrical contact with the second capture bed and the capture method further includes applying a voltage to the second electrode that is in electrical contact with the second capture bed.
  • the second capture bed is adjacent to the first capture bed with a separator disposed between the first and second capture beds.
  • 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.
  • the vessel comprises a capture bed stack comprising a plurality of capture beds. In some embodiments, the plurality of capture beds are separated from each other by one or more separators.
  • the plurality of capture beds are in electrical contact with the first or second electrode.
  • the capture method further comprises applying a positive voltage to the first electrode, wherein the first electrode is in electrical contact with a first plurality of capture beds; and applying a negative voltage to the second electrode, wherein the second electrode is in electrical contact with a second plurality of capture beds.
  • the first plurality of capture beds are stacked in an alternating fashion with the second plurality of capture beds.
  • 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.
  • 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.
  • the ionic contaminant comprises an organic end with an ionic moiety.
  • the ionic contaminant is selected from the group consisting of a polyfluoroalkyl ion, a borate, a phosphate, a polyphosphate, a sulfate, an organic acid, a fatty acid, a humic substance, a shortchain PFAS, a water-soluble medication, a detergent, a water- soluble insecticide, a water-soluble fungicide, a water-soluble germicide, and any combination thereof.
  • the ionic contaminant is a polyfluoroalkyl ion.
  • the polyfluoroalkyl ion is perfluorooctanesulfonate or perfluorooctanoate.
  • the contaminated aqueous mixture further comprises inorganic contaminants.
  • the inorganic contaminants include iron or manganese.
  • 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 can be removed by the use of one or more additives in the wash liquid or in a separate rinse liquid.
  • the use of the additive(s) reduces the amount of time needed to regenerate the capture bed and/or reduces the volume of wash liquid needed to regenerate the capture bed.
  • FIG. 2A can also be described in terms of a capture method of which it illustrates.
  • Water comprising a high concentration of PFOA and/or PFOS contaminant is flowed into a separation vessel that houses a plurality of capture beds in a stack ("cell stack").
  • cell stack a stack
  • the PFOA and/or PFOS ionic contaminant is bound to the capture bed.
  • water with a low concentration of PFOA and/or PFOS flows out of the separation vessel via an outlet line.
  • Flow through the outlet line is controlled by a valve, which is open during the capture cycle ("system in use”).
  • a second outlet line for use during a regeneration cycle is closed.
  • the system of FIG. 3 can also be described in terms of an integrated capture and regeneration method.
  • contaminated water from the raw water tank flows into the two separation vessels (activated carbon EDI filtration column and activated graphite EDI concentrating column). This flow is controlled by a valve and a pump for each separation vessel as shown. Voltage is applied to the capture beds in each separation vessel. The water with contaminant removed by the capture beds is flowed to a clean water tank, which flow is controlled by further valves.
  • the outlet flow of the separation vessels may be recirculated, as controlled by a recirculation valve, to the raw water tank for additional cycle(s) of purification.
  • wash liquid from a waste water tank is flowed through the separation vessels and also controlled using the same valves and pumps as during the capture cycle.
  • the voltage is modulated during the regeneration cycle to drive release of the bound contaminant from the capture bed as the wash liquid flows through the separation vessel.
  • the wash liquid with released contaminant (“extract") is flowed to a precipitator where it is mixed with regeneration fluid that is pumped into the precipitator.
  • the regeneration fluid comprises a sequestration agent (e.g., a counter ion) that forms an aggregate contaminant phase with the released contaminant.
  • the aggregate contaminant phase precipitates from the wash liquid in the precipitator and the solids are collected in a settler and removed. Wash liquid exiting the precipitator/settler is filtered and returned for continued use in washing the capture beds.
  • FIG. 4 shows a flowchart of the testing method.
  • a first carbon substrate was selected, either granulated activated carbon (GAC) or St Mary's carbon beads. The dry mass of the substrate was recorded. The substrate was next soaked in water and the wet mass mas recorded. The substrate was then dried in an oven and the mass after drying recorded. The substrate was next soaked in water followed by soaking overnight in a mixture of water and a specified and recorded mass of contaminant - either octanoic acid (OA) or PFOA. The wet mass of the substrate was then recorded to determine capture of OA/PFOA.
  • GAC granulated activated carbon
  • PFOA octanoic acid
  • the substrate was next soaked overnight in a solution of water and a specified and recorded mass of sequestration agent - either Ca(OH)2 or CaCk. NaOH was also added in the case of CaCk. After soaking and washing, the wet mass of the substrate was recorded. The substrate was then dried in oven and the dry mass after drying was recorded. The sequestration agent solution was dried and the mass of precipitate from the solution was recorded.
  • the substrate was then dried in oven and the dry mass after drying was recorded.
  • the sequestration agent solution was dried and the mass of precipitate from the solution was recorded.
  • Tables 1 - 4 show the results of the mass measurements for the experiment over the course of the initial wash procedure and three rounds of capture, regeneration and sequestration.
  • Table 5 shows the recovered mass of precipitate recovered for each round.
  • FIG. 5 shows visual observation of St. Mary's Beads (activated carbon beads) over the course of the first round of testing.
  • the results demonstrated that the carbon substrates were able to releasably capture OA and PFOA, and that the sequestration agent (calcium hydroxide or calcium chloride) was able to bind the OA or PFOA, be released from the carbon substrate, and be sequestered as a precipitate. The process was repeatable, showing the ability to capture OA and PFOA on the carbon substrate and subsequently regenerate the carbon substrate for multiple uses.
  • Table 6 Raw data for each of the 20 flasks tested. All prewash adsorbances were measured on the 13 ml method.
  • Calgon F400 activated carbon was rinsed with DI water and dried at 100 °C in a vacuum oven. 0.1 g +/- 0.001 PFOA was weighed and placed into a 2 L clean glass bottle. 2 L of deionized water was added to bottle, via volumetric flask. Actual input weights and volumes were recorded. PFOA was stirred until completely dissolved.
  • 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.
  • 1% acetic acid wash was prepared by diluting 5% vinegar.
  • 125 ml of Ca(OH)2 stock solution was measured into each flask and shaken at 150 rpm for 1 hour.
  • Regeneration solution was removed by pouring off liquid. Rinses were continued according to Table 6. Any following regeneration fluid rinse was shaken at 150 rpm for an hour, following acid or water rinses occurred for 30 minutes at 150 rpm. Any acid rinses were completed after the regeneration wash(es) and prior to the water washes. The solutions were poured off before the next rinse.
  • each flask was dosed again with 225834.6572 pg/kg PFOA solution.
  • the UV Spectrophotometer was set to 664 nm. The organic and aqueous phases were separated cleanly in a test tube, and organic phase was removed, and placed into a cuvette. The cuvette was placed, with water-saturated octanol, in the UV Spectrophotometer to zero the machine, then the cuvette with sample was placed and ran to measure UV absorbance.
  • pH probe was removed from storage solution, rinsed with deionized water, and gently wiped with Kimwipe. 4.01, 7.01, and 10.01 solutions were placed in vials. Probe was calibrated to 7.01, then to 4.01 and 10.01, then pH was checked for the 7.01 calibration again. After calibration, each flask was tested directly (with carbon in the flask), swirling the flask while testing and rinsing the probe between standards.
  • Table 7 shows equilibrium concentrations and percent recovery of sorptive capacity for each sample. Percent recovery was calculated by dividing the mass sorbed for fresh carbon by the mass sorbed for regenerated carbon and multiplying by 100.
  • Table 8 is a summary table showing the average percent recovery of sorptive capacity for the high number and low number of rinses for each process step. The difference between the percent recovery for the high and low number of rinses for each demonstrates the level of importance of each washing step (regeneration fluid, wash water, acetic acid rinse) on the percent recovery. [0136] Table 8:
  • Table 9 shows the average mass sorbed and percent standard deviation for all duplicates in each condition.
  • Table 10 is a summary table showing the average pH for the high number and low number of rinses for each process step. The difference between the pH for the high and low number of rinses for each demonstrates the level of importance of each washing step
  • Example 3 Regeneration of Samples with Mixed Contaminant
  • Calgon F400 activated carbon was rinsed with DI water and dried.
  • PFOA, K-PFOS, and PFNA stock solutions were prepared.
  • a humic acid solution was 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, carbon samples were exposed to contaminant solutions as shown in Table 11 and allowed to reach equilibrium, then samples were regenerated with Ca(OH)2 solution, regeneration solution was poured off, carbon bed samples were rinsed again with regeneration solution, and then finally carbon samples were treated a second time with same contaminant solutions as shown in Table 11. Absorption of contaminant was tested in fresh and regenerated carbon bed samples with and without humic acid as shown in Table 11.
  • Results of absorption testing are shown in Figures 6-11.
  • the carbon bed effectively captured PFOA, PFNA, and PFOS from the mixed contaminant solution both for fresh carbon samples and regenerated carbon samples. Capture was effective both in the presence and absence of humic acid. Thus, the regenerated system was effective for capturing mixed contaminants.
  • a small column (10 cm tall x 1.5 cm diameter) was loaded with freshly rinsed and dried GAC (14-15 g Calgon F400) as a capture bed.
  • the capture bed was rinsed with DI water and then dosed with a 100 ppm PFOA solution.
  • the filtrate was sampled every 3000s until 31 samples were collected for producing a first curve of PFOA concentration in the filtrate.
  • the dosing solution was pumped at a rate where the contact time was approximately 160s and the column filtered 12-14L until sampling was complete.
  • Regeneration fluids were pumped through the column in order, with volumes chosen to be 50x or more of the free volume of the column.
  • the first regeneration solution was a detergent solution of octanoic acid (0.2g in 1L DI water).
  • the second regeneration solution was an aluminum hydroxide solution (320g NaOH and 480g Al(OH)3 in 16L DI water).
  • the third regeneration solution was a calcium hydroxide solution (4g Ca(OH)2 in 2L DI water).
  • the fourth regeneration solution was a sodium hydroxide solution (4g NaOH in 1L DI water).
  • the fifth regeneration solution was an acid wash solution (250mL 12.39M HC1 solution in 15.75L DI water). Regeneration DI water was then pumped through the column until filtrate was pH > 5. To produce the second curve for regenerated capture bed, the same procedure was followed for dosing with 100 ppm PFOA solution.
  • Figure 12 shows the initial and regenerated breakthrough curves for the column filtering the 100 ppm PFOA feed solution.
  • the feed concentration is shown as the dashed line.
  • Early sample vials had low PFOA concentration, showing capture of PFOA on the carbon bed, although some PFOA is able to pass through the column even for early vials.
  • the regeneration curve shows that the regenerated bed captured PFOA and closely followed the performance of the fresh bed with a slight decrease in capture rate.

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Abstract

L'invention concerne un système et un procédé de purification de l'eau par capture des contaminants dans un mélange aqueux. L'invention concerne également un système et un procédé permettant de régénérer le système de capture. L'invention concerne en outre un système et un procédé intégrés de capture et de régénération comprenant un récipient de séparation qui abrite un lit de capture et, éventuellement, une électrode en contact électrique avec le lit, ainsi qu'une source d'énergie servant à appliquer une tension à l'électrode. La tension appliquée renforce la capture du contaminant à partir du liquide aqueux sur le lit de capture et la modulation de la tension appliquée renforce la libération du contaminant sur le lit de capture dans le liquide de lavage aqueux pour régénérer le lit. Le liquide de lavage aqueux peut contenir un contre-ion qui se lie au contaminant en formant une phase de contaminant agrégée qui se sépare du liquide de lavage aqueux.
EP21740390.6A 2020-06-18 2021-06-18 Système pour élimination de contaminants pouvant être régénéré Pending EP4168362A1 (fr)

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