SYSTEM FOR REMOVING PER- AND POLYFLUOROALKYL SUBSTANCES (PFAS) FROM A SOLUTION HAVING PFAS THEREIN USING FOAM FRACTIONATION

A system for removing PFAS from a solution having PFAS therein using foam fractionation is featured. The system includes at least one first foam fractionation subsystem including a vessel configured to receive the solution having PFAS therein and configured to generate microbubbles, turbulence, and foam to remove a majority of the PFAS and generate a treated solution and a flow of foam having the removed PFAS therein. The system also includes a heating and dehumidification subsystem coupled to the at least one foam fractionation subsystem and configured to generate a flow of heated dehumidified gas. The at least one foam fractionation subsystem is configured to output the flow of foam having the removed PFAS therein into the flow of heated dehumidified gas such that the flow of a heated dehumidified gas collapses the flow of foam having the removed PFAS therein into a flow of liquid having the removed PFAS therein.

FIELD OF THE INVENTION

This invention relates to a system for removing per-and polyfluoroalkyl substances (PFAS) from a solution having PFAS therein using foam fractionation.

BACKGROUND OF THE INVENTION

Foam fractionation has been utilized in the large-scale aquarium industry for decades. It works by introducing turbulence combined with thousands of microbubbles at the bottom of a large water column while the dirty water enters at the top of the column and exits at the bottom. As the water is moving down the column toward the exit, the bubbles work to trap particles and unwanted waste, floating contaminants to the surface. In the aquarium industry this is typically targeting fish waste and proteins, floating the particulate to the surface where it may be removed via a skimmer. Foam fractionation may have a dramatically lower cost of operation when compared to more intense membrane, and filtration technologies and has gained major popularity in the aquarium, and aquaculture industries due to the ease of operation and effectiveness of removal.

PFAS compounds are polar, with charged hydrophilic heads and fluorinated hydrophobic tails. This chemical structure results in molecules that seek the air-water interface. This is a major reason why PFAS is the backbone of Aqueous Film Forming Foam (AFFF) or firefighting foam. Much in the way foam fractionation works to remove proteins in an aquarium environment, foam fractionation also has its place in groundwater remediation, water, and wastewater treatment, specifically for the removal of PFAS. The introduction of turbulence and thousands of microbubbles at the base of a water column creates immense surface area for PFAS compounds to join the air-water interface, and float with the bubbles to the top of the column where they can be separated from the treated water (raffinate) and concentrated into foam or foamate.

Conventional foam fractionation systems and methods typically produce a large volume of waste foam or foamate having removed PFAS therein, which may be difficult and cumbersome to handle and/or further treat.

Thus, there is a need for a foam fractionation system and method which reduces the volume of waste foam or foamate having removed PFAS therein and which creates a concentrated flow of a liquid having removed PFAS therein and which reduces the volume of PFAS waste.

BRIEF SUMMARY OF THE INVENTION

In one aspect, a system for removing per-and polyfluoroalkyl substances (PFAS) from a solution having PFAS therein using foam fractionation is featured. The system includes at least one first foam fractionation subsystem including a vessel configured to receive the solution having PFAS therein and configured to generate microbubbles, turbulence, and foam to remove a majority of the PFAS and generate a treated solution and a flow of foam having the removed PFAS therein. The system also includes a heating and dehumidification subsystem coupled to the at least one foam fractionation subsystem and configured to generate a flow of heated dehumidified gas. The at least one foam fractionation subsystem is configured to output the flow of foam having the removed PFAS therein into the flow of heated dehumidified gas such that the flow of a heated dehumidified gas collapses the flow of foam having the removed PFAS therein into a flow of liquid having the removed PFAS therein.

In one example, the flow of heated dehumidified gas may be configured to reduce a volume of the flow of foam having the removed PFAS therein. The flow of liquid having the removed PFAS therein and the heated dehumidified gas may be directed to a foamate break tank. A pitched line coupled between the vessel and the foamate break tank may be configured to direct the flow of liquid having the removed PFAS therein to the foamate break tank. The flow of heated dehumidified gas may be recirculated from the foamate break tank to the heating and dehumidification subsystem and to the vessel. Recirculating the heated and dehumidified gas may be configured to reduce an energy input required to collapse and/or reduce the volume of the foam. The at least one foam fractionation subsystem may include a diffuser subsystem configured to generate the microbubbles and/or nanobubbles, the turbulence, and the foam. The at least one foam fractionation subsystem may include a venturi eductor configured to introduce and mix a gas into a recycled solution having PFAS therein and generate a two-phase flow of microbubbles and a solution having PFAS therein and a modified diffuser including a vortex tee inside a cylindrical baffle configured to receive the two-phase flow and induce rotational movement that generates intense mixing and turbulence to maximize the formation and distribution of microbubbles and foam to enhance removal of PFAS from the solution having PFAS therein. The vortex tee may be spaced from a surface of the cylindrical baffle by a predetermined distance to maximize the rotational movement and turbulence of the two-phase flow of microbubbles and water having PFAS therein. The cylindrical baffle may be sized and positioned to separate the two-phase flow of microbubbles and water having PFAS therein from the treated solution having a majority of the PFAS removed. The at least one pump may be coupled to the vessel and the venturi eductor. The at least one pump operated in cavitation such that the venturi eductor generates a two-phase flow of microbubbles and/or nanobubbles and the solution having PFAS therein. The modified diffuser may be configured to receive the two-phase flow and induce rotational movement that generates intense mixing and turbulence to augment the formation and distribution of microbubbles and/or nanobubbles and foam to enhance removal of PFAS from the solution having PFAS therein. The system may include a super-loading subsystem which may be configured to receive the flow of liquid having the removed PFAS therein and configured to remove PFAS from the flow by sorbing PFAS onto adsorptive media to create a concentrated PFAS waste product.

In another aspect, a method for removing per-and polyfluoroalkyl substances (PFAS) from a solution having PFAS therein using foam fractionation is featured. The method includes receiving the solution having PFAS therein and generating microbubbles, turbulence, and foam to remove a majority of the PFAS, generating a treated solution and a flow of foam having the removed PFAS therein, generating a flow of heated dehumidified gas, and outputting the flow of foam having the removed PFAS therein into the flow of heated dehumidified gas such that the flow of a heated dehumidified gas collapses the flow of foam having the removed PFAS therein into a flow of liquid having the removed PFAS therein.

In one example, the flow of heated dehumidified gas may be configured to reduce a volume of the flow of foam having the removed PFAS therein. The flow of liquid having the removed PFAS therein and the heated dehumidified gas may be directed to a foamate break tank. The flow of heated dehumidified gas may be recirculated from the foamate break tank to the heating and dehumidification subsystem and to the vessel. Recirculating the heated and dehumidified gas may be configured to reduce an energy input required to collapse and/or reduce the volume of the foam. The method may include a super-loading process may be configured to receive the flow of liquid having the removed PFAS therein and configured to remove PFAS from the flow by sorbing PFAS onto adsorptive media to create a concentrated PFAS waste product.

In another aspect, a system for removing long-chain and short-chain PFAS from a solution having PFAS therein using foam fractionation is featured. The system includes at least one first foam fractionation subsystem configured to receive the solution having PFAS therein and configured to generate microbubbles, turbulence, and foam to remove a majority of long-chain PFAS and generate a treated flow of a solution having a majority of the long-chain PFAS removed. The system also preferably includes at least one foam boosting subsystem configured to introduce at least one foam boosting agent into the treated flow of solution having a majority of the long-chain PFAS removed. The at least one second foam fractionation subsystem is configured to receive the treated solution having a majority of the long-chain PFAS removed and the foam boosting agent. The at least one second foam fractionation subsystem is configured to generate microbubbles, turbulence, and foam. The foam boosting agent is preferably configured to augment the formation of foam to facilitate the removal of short-chain PFAS. The at least one second foam fractionation subsystem is configured to generate a treated flow of a solution having a majority of the long-chain PFAS removed and a majority of the short-chain PFAS removed.

In one example, the foam boosting agent may include at least one supplemental surfactant. The at least one supplemental surfactant may include an anionic, cationic, zwitterionic, nonionic, and/or a protein-based surfactant.

In another aspect, a method for removing long-chain and short-chain PFAS from a solution having PFAS therein using foam fractionation is featured. The method includes receiving the solution having PFAS therein and generating microbubbles, turbulence, and foam to remove a majority of long-chain PFAS, generating a treated flow of a solution having a majority of the long-chain PFAS removed, introducing at least one foam boosting agent into the treated flow of solution having a majority of the long-chain PFAS removed, receiving the treated solution having a majority of the long-chain PFAS removed and the foam boosting agent, generating microbubbles, turbulence, and foam, the foam boosting agent is preferably configured to augment the formation of foam to facilitate the removal of short-chain PFAS, and generating a treated flow of a solution having a majority of the long-chain PFAS removed and a majority of the removed short-chain PFAS removed.

In one example, the foam boosting agent may include at least one supplemental surfactant. The at least one supplemental surfactant may include an anionic, cationic, zwitterionic, nonionic, and/or a protein-based surfactant.

DETAILED DESCRIPTION OF THE INVENTION

There is shown inFIG.1, one example of system10for removing PFAS from solution12having PFAS therein using foam fractionation. Solution12may include one or more of industrial wastewater, municipal wastewater, contaminated groundwater, landfill leachate, dilute AFFF from fire protection systems, or similar solution contaminated with PFAS.

System10includes at least one foam fractionation subsystem14which receives solution12having PFAS therein. In one design, fractionation subsystem14may receive a flow of solution12having PFAS therein, e.g., flow16of solution12having PFAS therein. As disclosed herein, “flow” may be a continuous flow often utilized in a flow-through reactor or vessel, or an intermittent flow typically utilized in sequencing batch processing.

Foam fractionation subsystem14generates microbubbles, exemplarily indicated at18, turbulence, and foam, also referred to herein as foamate, exemplarily indicated at20, to remove a majority of the PFAS from solution12and generate treated solution38. As defined herein, a majority is preferably greater than about 50% of the PFAS in solution12. In one design, foam fractionation subsystem14may generate flow22, also referred to herein as raffinate22, of treated solution38. As defined herein, flow22of treated solution38preferably contains less than about 50% of the PFAS in solution12. Foam fractionation subsystem14also generates flow24of foam or foamate having the removed PFAS therein.

System10also includes a heating and dehumidification subsystem26coupled to vessel36as shown which generates flow28of heated dehumidified gas. In one design, heating and dehumidification subsystem26preferably includes heating device30and dehumidifier32. In other examples, heating device30and dehumidifier32may be configured as a single device.

Foam fractionation subsystem14preferably outputs flow24of foam having the removed PFAS therein into the flow28of heated dehumidified gas as shown such that flow28of a heated dehumidified gas collapses flow24of foam having the removed PFAS therein into flow34of liquid having the removed PFAS therein. The heated dehumidified gas in flow28removes water from foam20in flow24which reduces the volume of foam or foamate20generated by system10and the method thereof (discussed below). The heat in flow28efficiently and effectively collapses foam20into flow34of liquid having removed PFAS therein. The combination of removing water from the foam having removed PFAS therein and efficiently collapsing the foam into a liquid as discussed above minimizes the amount to PFAS waste generated by system10and the method thereof.

In one design, flow34of liquid having the removed PFAS therein, and flow28of heated dehumidified gas are preferably directed to foamate break tank40, which preferably collects flow34of liquid having the removed PFAS therein. Foamate break tank40preferably outputs flow42of liquid having the removed PFAS therein. Flow42may be a waste product that may be disposed, destroyed, or further treated, as discussed below.

In one example, flow28of the heated dehumidified gas may be recirculated from foamate break tank40to heating and dehumidification subsystem26by line50and to vessel16by line52. Recirculating flow28of heated, and dehumidified gas preferably reduces the energy input required to collapse flow24of foam into flow34of liquid having the removed PFAS therein.

In one example, line52coupled between heating and dehumidification subsystem26and foamate break tank40may be pitched to direct flow34of liquid, having the removed PFAS therein to foamate break tank40, e.g., as shown inFIG.2.

Foam fractionation subsystem14preferably includes diffuser subsystem54, which preferably generates microbubbles18, turbulence, and foam20. In one example, diffuser subsystem54preferably introduces flow56of a gas, e.g., air, nitrogen, carbon dioxide, or similar type gas, to generate and distribute microbubbles18, turbulence, and foam20.

Foam fractionation subsystem14may include exhaust vent58which preferably outputs flow60of exhaust gas. Flow60of exhaust gas is preferably approximately equal to flow56of gas. Flow60may include trace amounts of PFAS. To remove any PFAS in flow60, foam fractionation subsystem14may include exhaust gas removal subsystem148which preferably removes a majority of the PFAS from flow60. In one example, exhaust gas cleaning subsystem148may include a carbon canister, or similar type device.

Foam fractionation subsystem14may also include collection tank150, which preferably receives condensate from dehumidifier32by line152. The condensate in collection tank150may include PFAS and may be directed back to inlet44by line154and/or to super-loading subsystem62(discussed below) as flow156.

In one design, foam fractionation subsystem14may include super-loading subsystem62which preferably receives flow42of liquid having a majority of the removed PFAS therein and/or flow156condensate in collection tank150as shown. In one example, super-loading subsystem62preferably removes PFAS from flow42and/or flow156by adsorbing PFAS onto an adsorptive media.

In one example, super-loading subsystem62may be configured as a small vessel, e.g., vessel64shown in caption66having an adsorptive media68therein. Adsorptive media68preferably absorbs the PFAS in flow42to create a concentrated PFAS waste product that may be disposed of or destroyed. Adsorptive media68may include ion exchange resin, granular activated carbon (GAC), synthetic media, or a combination thereof, or similar type adsorptive media. See e.g., U.S. Pat. Nos. 10,287,185, 10,913,668 and 11,027,988 by the assignee hereof, incorporated by reference herein.

In another design, foam fractionation subsystem14′,FIG.3, where like parts have been given like numbers, preferably includes vessel36′ which preferably includes inlet70, which receives solution12having PFAS therein. In one design, similar as discussed above, foam fractionation subsystem14′ may receive flow16of solution12having PFAS therein, which may be continuous flow or an intermittent flow.

In one design, venturi eductor72may generate nanobubbles, exemplarily indicated at18′, by operating pump78in cavitation. Nanobubbles18′ preferably increase the surface area of air-water interface thereby enhancing efficiently of foam fractionation. In other examples, system10and the method thereof may include a nanobubble generation subsystem (not shown) to generate nanobubbles18′, as known by those skilled in the art.

Foam fractionation subsystem14′ also preferably includes modified diffuser subsystem45which augments the production and distribution of microbubbles18and/or nanobubbles18′, and foam or foamate20. Modified diffuser subsystem45preferably includes vortex tee86disposed inside cylindrical baffle88as shown. Vortex tee86receives the two-phase flow80by line84and induces rotational movement or vortex formation of the two-phase flow inside cylindrical baffle88to generate intense mixing and turbulence. The intense mixing and turbulence provided by modified diffuser subsystem45significantly increases the production and distribution of microbubbles18and/or nanobubbles18′, e.g., when compared to diffuser44,FIG.1, such that the more PFAS in flow16attach to the increased concentration of microbubbles18and/or nanobubbles18′ provided by modified diffuser subsystem45This preferably enhances removal of PFAS from solution12having PFAS therein and, increases the production and distribution of foam or foamate20.

Similar as discussed above with reference toFIG.1, foam fractionation subsystem14′ outputs flow24of foam or foamate20having the removed PFAS therein into flow28of heated dehumidified gas as shown such that flow28of a heated dehumidified gas collapses flow24of foam having the removed PFAS therein into flow34of liquid having the removed PFAS therein.

FIG.4is top view of modified diffuser subsystem45including vortex tee86and cylindrical baffle88and, shows an example of the direction of two-phase flow90, also shown inFIG.3, toward surface92,FIG.4, of cylindrical baffle88, indicated by arrows90. Preferably, vortex tee86is spaced from surface92by a predetermined distance, e.g., distance d-94, to maximize the rotational movement or vortex formation, which generates intense mixing and turbulence to augment the formation and distribution of microbubbles18and/or nanobubbles18′ and, foam or foamate20to enhance removal of PFAS from solution12having PFAS therein. Distance d-94will vary depending on the size of vessel36′. The diameter of cylindrical baffle88is preferably chosen to maximize the rotational movement or vortex formation. A diameter too large or too small will provide non-optimal rotational movement or vortex formation. The diameter of cylindrical baffle88will vary depending on the size of vessel36′.

In one exemplary operation, solution12,FIG.3, having PFAS therein enters vessel36′ at inlet70as shown, e.g., as flow16of solution12having PFAS therein. As flow16travels down vessel36′, indicated by arrows100, the PFAS in flow16attaches to the high concentration of microbubbles18and/or nanobubbles18′ provided by modified diffuser subsystem45and forms foam or foamate20. As flow16travels further downward in vessel36′, against the upward two-phase flow of microbubbles18and/or nanobubbles18′ and solution12having PFAS therein, indicated by arrows102, more PFAS attach to the highly concentrated microbubbles18and/or nanobubbles18′. By the time flow16reaches the bottom of vessel36′, indicated at104, the majority of the PFAS has been removed and treated solution21is preferably output, e.g., as flow22, in one example via outlet110, and recycled flow76of solution12having PFAS therein is preferably directed to venturi eductor72.

Similar as discussed above with reference toFIGS.1and2, flow34,FIG.3, of liquid having the removed PFAS therein and flow28of heated dehumidified gas may be directed to foamate break tank40which preferably collects flow34of liquid having the removed PFAS therein. Foamate break tank40preferably outputs flow42of liquid having the removed PFAS therein. Flow42may be a waste product that may be disposed of, destroyed, or further treated, as discussed below.

Similar as discussed above with reference toFIG.1, in one design, line52coupled between heating and dehumidification subsystem26and foamate break tank40may be pitched to direct flow34of liquid having the majority of the removed PFAS therein to foamate break tank40, similar as discussed above with reference toFIG.2.

In one example, flow28of the heated dehumidified gas may be recirculated from foamate break tank40to heating and dehumidification subsystem26by line50and to vessel36′ by line52, similar as discussed above with reference toFIG.1. Recirculating flow28of heated and dehumidified gas preferably reduces the energy input required to collapse flow24of foam into flow34of liquid having the removed PFAS therein.

Similar as discussed above with reference toFIG.1, foam fractionation subsystem14′ may also include collection tank150which receives condensate from dehumidifier32by line152. The condensate in collection tank150may include PFAS and may be directed to inlet70by line154and/or super-loading subsystem62as flow156(discussed below).

Foam fractionation subsystem14′,FIG.3, may include super-loading subsystem62, which preferably receives flow42of liquid having the majority of the removed PFAS therein and/or flow156as shown. Super-loading subsystem62preferably removes PFAS from flow42and/or flow156by sorbing PFAS onto adsorptive media to create concentrated PFAS waste product, similar as discussed above with reference toFIG.1.

In one example, super-loading subsystem62may be configured as a small vessel, e.g., vessel64shown in caption66having an adsorptive media68therein. Adsorptive media68preferably adsorbs the PFAS in flow42to create concentrated PFAS waste product that may be disposed of or destroyed. Adsorptive media68may include anion exchange resin, granular activated carbon (GAC), synthetic media, or a combination thereof, or similar type adsorptive media. See e.g., U.S. Pat. Nos. 10,287,185, 10,913,668 and 11,027,988, cited supra.

Flow28of the heated dehumidified gas may be recirculated from foamate break tank40to heating and dehumidification subsystem26by line50and to vessel36′ by line52. Recirculating flow28of heated and dehumidified gas preferably reduces the energy input required to collapse flow24of foam into flow34of liquid having the PFAS therein.

Foam fractionation subsystem14may include exhaust vent58which preferably outputs flow60of exhausts gas. Flow60of exhaust gas is approximately equal to flow56of gas. Flow60may include trace amounts of PFAS. To remove any PFAS in flow60, foam fractionation subsystem14may include exhaust gas removal subsystem140which preferably removes a majority of the PFAS from flow60and outputs flow162of treated exhaust gas. In one example, exhaust gas cleaning subsystem148may include a carbon canister, or similar type device.

One example of the method for removing PFAS from a solution having PFAS therein using foam fractionation includes receiving the solution having PFAS therein and generating microbubbles, turbulence, and foam to remove a majority of the PFAS, step200,FIG.5, generating a treated solution and a flow of foam having the removed PFAS therein, step202, generating a flow of heated dehumidified gas, step204, and outputting the flow of foam having the removed PFAS therein into the flow of heated dehumidified gas such that the flow of a heated dehumidified gas collapses the flow of foam having the removed PFAS therein into a flow of liquid having the removed PFAS therein, step206.

The result is system10and the method thereof efficiently and effectively removes PFAS from a solution having PFAS therein using foam fractionation. System10preferably reduces the volume of waste foam or foamate having removed PFAS therein and preferably creates a concentrated flow of a liquid having removed PFAS therein, or concentrated PFAS waste product, which preferably reduces the volume of PFAS waste.

Long-chain PFAS compounds, disclosed herein as “long-chain PFAS”, typically are designated having six or more carbons for perfluoroalkyl sulfonic acids and having seven or more carbons for perfluoroalkyl carboxylic acids. Short-chain PFAS compounds, disclosed herein as “short-chain PFAS”, typically have less than six carbons for perfluoroalkyl sulfonic acids and less than seven carbons for perfluoroalkyl carboxylic acids.

It is well known that is difficult to remove short-chain PFAS from a solution having PFAS therein using foam fractionation. Thus, conventional foam fractionation methods may be ineffective at removing both long and short-chain PFAS from a solution having PFAS therein.

FIGS.6A and6Bshow one example of system100for removing long-chain and short-chain PFAS from solution102having PFAS therein using foam fractionation. Solution102may include one or more of industrial wastewater, municipal wastewater, contaminated groundwater, landfill leachate, dilute AFFF from fire protection systems, or similar solution contaminated with PFAS.

System100includes at least one first foam fractionation subsystem104,FIG.6A, which receives solution102having PFAS therein. In one design, first foam fractionation subsystem104may receive a flow of solution102having PFAS therein, e.g., flow106of solution102having PFAS therein. As disclosed herein, “flow” may be a continuous flow often utilized in a flow-through reactor or vessel, or an intermittent flow typically utilized in sequencing batch processing.

At least one first foam fractionation subsystem104generates microbubbles120and/or nanobubbles122, turbulence, and foam132to remove a majority of long-chain PFAS and generate treated flow140of solution142having a majority of the long-chain PFAS removed, as discussed in detail below. As disclosed in this example, a majority is preferably greater than about 50% of the long-chain PFAS in solution12.

First foam fractionation subsystem104preferably includes modified diffuser subsystem45′, having a similar design and operation as modified diffuser45discussed above with reference toFIG.3, which preferably induces intense mixing and turbulence to augment the formation and distribution of microbubbles120and/or nanobubbles122and foam or foamate132to enhance removal of long-chain PFAS from solution102having PFAS therein.

In one design, venturi eductor110preferably generates nanobubbles122by operating pump116in cavitation. Nanobubbles122preferably increase the surface area of air-water interface thereby enhancing efficiently of foam fractionation. In other examples, system100may include a nanobubble generation subsystem (not shown) to generate nanobubbles122, as known by those skilled in the art.

System100also includes at least one second foam fractionation subsystem170,FIG.6B, which receives treated solution142having a majority of the long-chain PFAS removed and a foam boosting agent from foam booting subsystem160, as discussed below. At least one second foam fractionation subsystem170preferably generates microbubbles186and/or nanobubbles188, turbulence, and foam178. The foam boosting agent preferably augments the formation of foam178to facilitate the removal of short-chain PFAS. At least one second foam fractionation subsystem170generates treated flow230of solution232having a majority of the long-chain PFAS removed and a majority of the short-chain PFAS removed. As defined herein, a majority is preferably greater than about 50% of the long-chain PFAS and 50% of the short-chain PFAS in solution232.

In one exemplary operation, flow106of solution102having PFAS enters vessel134. As flow106travels down vessel134, indicated by arrows136, the long-chain PFAS in flow106attach to the high concentration of microbubbles120and/or nanobubbles122provided by modified diffuser subsystem45′ and forms foam or foamate132. As flow106travels further downward in vessel134, against the upward two-phase flow of microbubbles and solution102having PFAS therein, indicated by arrows140, more long-chain PFAS attaches to the highly concentrated microbubbles120and/or nanobubbles122. By the time flow106reaches the bottom of vessel134, indicated at138, the majority of the long-chain PFAS has been removed. At least one foam fractionation subsystem104produces flow140, or raffinate140, of treated solution142having majority of the long-chain PFAS removed. Flow140of treated solution142is preferably output by outlet144, and recycled flow114of solution102having PFAS therein is preferably directed to venturi eductor112.

In one example, first foam fractionation subsystem104preferably outputs flow166of foam132or foamate132which may be directed to foamate break tank180which preferably outputs flow182, or liquid182, of liquid184having a majority of the removed long-chain PFAS therein. In one example, flow182may be directed to super-loading subsystem188, of similar design as super-loading subsystem62, discussed above with reference toFIGS.1and3, to create a concentrated PFAS waste product. The concentrated PFAS waste product may be disposed of or destroyed.

System100also includes foam boosting subsystem160,FIG.6B, which preferably injects at least one boosting agent into treated flow140of solution142having the majority of the long-chain PFAS removed. In one example, the foam boosting agent may include at least one supplemental surfactant. The supplemental surfactant may include an anionic, cationic, zwitterionic, nonionic, and/or a protein-based surfactant.

System100also preferably includes at least one second foam fractionation subsystem170which preferably includes vessel172and inlet174which receives treated flow140of solution142having a majority of the long-chain PFAS removed and the at least one foam boosting agent injected by foam boosting subsystem160.

In this example, second foam fractionation subsystem170preferably includes venturi eductor176which introduces and mixes gas192, e.g., air, nitrogen, carbon dioxide, or similar type gas, into recycled flow180of solution142having a majority of the long-chain PFAS removed, preferably provided by pump182. Venturi eductor176preferably generates two-phase turbulent flow184of microbubbles186and/or nanobubbles188and treated solution140solution having a majority of the long-chain PFAS removed in line190. In one example, venturi eductor72may be available from Mazzei Injector Company, LLC., Bakersfield, CA 93307.

In one design, venturi eductor176may generate nanobubbles188by operating pump182in cavitation. Nanobubbles188preferably increase the surface area of air-water interface thereby enhancing efficiently of foam fractionation. In other examples, system100may include a nanobubble generation subsystem (not shown) to generate nanobubbles188, as known by those skilled in the art.

Second foam fractionation subsystem170also preferably includes modified diffuser subsystem45″, of similar design and operation as modified diffuser subsystem45discussed above with reference toFIG.3, which preferably induces intense mixing and turbulence to augment the production and distribution of microbubbles186and/or nanobubbles188, and foam or foamate178.

In one exemplary operation, flow140of treated solution142having the majority of long-chain PFAS removed and the booting agent introduced by foam boosting subsystem160into flow140enters vessel172at inlet174. As flow140travels down vessel172, indicated by arrows220, the short-chain PFAS in flow140attach to the high concentration of microbubbles186and/or nanobubble188provided by modified diffuser subsystem45″ and forms foam or foamate178. As flow140travels further downward in vessel172, against the upward two-phase flow of microbubbles186and/or nanobubbles188and solution142having the majority of the long-chain PFAS removed, indicated by arrows222, short-chain PFAS attaches to the highly concentrated microbubbles186and/or nanobubble188. The foam boosting agent discussed above augments the formation of foam178to facilitate the removal of a majority of the short-chain PFAS. The foam boosting agent preferably works by creating an ion pair with the short chain PFAS, thereby enhancing the foaming potential of the short chains, which do not t have as much natural foaming tendency as the longer chain PFAS. By the time flow140reaches the bottom of vessel172, indicated at224, the majority of the short-chain PFAS has been removed At least one second foam fractionation subsystem170preferably produces treated flow230, or raffinate230, of solution232having majority of the long-chain and short-chain PFAS removed. Treated flow or raffinate230is preferably output by outlet240and recycled flow180of solution142having a majority of the long-chain PFAS removed is preferably directed to venturi eductor176.

In one design, second foam fractionation subsystem172preferably outputs flow250of foam or foamate178having majority of the removed short-chain PFAS therein. Flow250may include a small amount of liquid produced from foam or foamate178that has collapsed into a liquid. In one example, flow250is preferably directed to foamate break tank252. In this example, foamate break tank252preferably collects flow250and collapses foam176into liquid254having a majority of the removed short-chain PFAS therein. Foamate break tank252preferably outputs treated flow256of liquid254having a majority of the short-chain PFAS removed therein. In one example, liquid flow256may be directed to super-loading subsystem190, of similar design as super-loading subsystem62, discussed above with reference toFIGS.1and3, to create a concentrated PFAS waste product. The concentrated PFAS waste product may be disposed of or destroyed.

Although as discussed above with reference toFIGS.6A and6B, system100may utilize a modified diffuser subsystem for at least one first foam fractionation subsystem104and at least one second foam fractionation subsystem170, in other designs, at least one first foam fractionation subsystem104and/or at least one second foam fractionation subsystem170may utilize a diffuser subsystem, such as diffuser subsystem54, discussed above with reference toFIG.1.

One example of the method for removing long-chain and short-chain PFAS from a solution having PFAS therein using foam fractionation includes receiving a solution having PFAS therein and generating microbubbles, turbulence, and foam to remove a majority of long-chain PFAS, step300,FIG.7, generating a treated flow of a solution having a majority of the long-chain PFAS removed, step302, introducing at least one foam boosting agent into the treated flow of solution having a majority of the long-chain PFAS removed, step304, receiving the treated solution having a majority of the long-chain PFAS removed and the foam boosting agent and generating microbubbles, turbulence, and foam, the foam boosting agent configured to augment the formation of foam to facilitate the removal of short-chain PFAS, step306, and generating a treated flow of a solution having a majority of the long-chain PFAS and a majority of the short-chain PFAS therein., step308.

Thus, the combination of first foam fractionation subsystem104in series with second foam fractionation subsystem170and foam boosting subsystem160, which preferably introduces at least one foam boosting agent, effectively and efficiently removes a majority of the long-chain and short-chain PFAS from solution102having PFAS therein.