Thermal remediation of soil contaminated with per- and polyfluoroalkyl substances (PFAS) with little or no waste byproduct

Abstract

The invention herein comprises systems, devices, and methods for the remediation of per- and polyfluoroalkyl substances, PFAS, including their precursors and degradation compounds such as volatile, semi-volatile, and non-volatile fluorinated alkene and alkane organic chemicals, OFCs, in media through heating the media using electrically powered thermal conduction heaters or other methods, to temperatures between approximately 250°C and 550°C.

Description

THERMAL REMEDIATION OF SOIL CONTAMINATED WITH PER- AND POLYFLUOROALKYL SUBSTANCES (PFAS) WITH LITTLE OR NO WASTE BYPRODUCTINVENTORSJohn C. LaChanceAlyson FortuneSaren EriksenSteffen Griepke Dam NielsenErin HauberGregory MacLeodJames P. Galligan Jr.PRIORITY CLAIM

[0001] This application claims priority to and / or the benefit of U.S. provisional patent application serial number 63 / 651,114 filed May 23, 2024. The foregoing application is incorporated by reference in its entirety as if fully set forth herein.FIELD OF THE INVENTION

[0002] This invention relates generally to a system, device, and method for the remediation of per- and polyfluoroalkyl substances (“PFAS”) from soil and other media such as, but not limited to, sediments, sludges, soil washing fines, wastewater solids, bio solids, granular activated carbon (GAC) or other sorptive media.BACKGROUND OF THE INVENTION

[0003] PFAS, including, its precursors (such as fluorotelomer alcohols and other compounds that can be transformed into regulated target PFAS), refer to a group of nearly 15,000 synthetic organic compounds that have become the subject of an increasing level of regulatory scrutiny and regulation from governmental agencies across the US and around the world, as concerns have arisen over the potential health effects and the persistence of PFAS compounds in the environment and the human body. PFAS compounds were widely used in a variety of industries and many household goods, including firefighting foams, heat-resistant and corrosion-resistant coatings, non-stick coatings, and fabric treatments, among other uses. There is substantial evidence that exposure to PFAS can lead to adverse human health effects.These PFAS compounds are persistent toxic pollutants that do not easily degrade or breakdown in the environment when they are released or leach to soil and groundwater, leading them to be described as “forever chemicals.” They consist of compounds with long carbon chains (e.g., typically C6 or longer), where the carbon atoms are saturated with fluorine atoms and a carboxylate or sulfonic surfactant group is attached to one end. Because of their chemical structure and the prevalence of C-F bonds, which are the strongest known covalent bond in nature, PFAS are typically semi-volatile polar surfactants that are thermally and chemically stable. Due to the physical properties of PFAS compounds and emerging regulatory and academic understanding of their persistence and toxicity in the environment and human body, there are limited direct disposal options for PFAS contaminated soil. As such, disposal of PFAS contaminated soil often requires expensive excavation, transport, and incineration approaches. Conventional thermal remediation methods for treatment of soil impacted with PFAS have focused on incineration and heating the soil to very high temperatures >900°C to achieve effective treatment and relied on expensive systems to handle and treat the vapors extracted from the heated soil, which can include PFAS, precursors and degradation compounds including volatile, semi-volatile, and non-volatile fluorinated alkene and alkane organic chemicals, referred to herein as Other Fluorinated Compounds (“OFCs”).

[0004] Thus, there is a need for an effective, economical, and sustainable solution to thermally treat soil, sediment, and other solids and media impacted with PFAS that optimizes the destruction and removal of PFAS and OFCs from both the soil and from the extracted off-gas vapor stream.SUMMARY

[0005] Specific details of certain embodiments of the invention are set forth in the following description and in the figures to provide a thorough understanding of such embodiments. The present invention may have additional embodiments, may be practiced without one or more of the details described for any particular described embodiment, or may have any detail described for one particular embodiment practiced with any other detail described for another embodiment.

[0006] Research into the thermal treatment of PFAS compounds has shown that the following process can be highly effective. First, heating clean sand (SiO2) with little to no calcium compounds such as calcium oxides, calcium hydroxide, or calciumcarbonate present, to 350°C in a stainless steel container results in greater than 99.5% removal of target PFAS compounds primarily through the degradation, volatilization and mineralization of the target PFAS compounds. Results from these studies indicate that approximately 40% of the fluorine associated with the PFAS remains in the soil as inorganic fluoride (likely chromium and iron fluorides) bound to mineral surfaces in the soil and approximately 60% of the fluorine leaves the soil through volatilization as the result of the degradation of the target PFAS to volatile and semi volatile fluorinated alkanes and alkenes, along with the formation and vapor transport of hydrofluoric acid (“HF”) out of the soil. Some direct volatilization of shorter-chained more volatile target PFAS may also occur.

[0007] Second, heating native soils with typical minerology and the presence of calcium compounds such as calcium carbonates to 400°C in stainless steel containers results in the complete degradation and mineralization of PFAS in the soil with all of the fluorine from the PFAS bound to the soil mineral surfaces primarily as calcium fluoride and possibly some chromium and iron fluorides, and no PFAS, fluorinated degradation products, or HF produced in the extracted vapor stream.

[0008] Third, passing the extracted vapors from the heated soil through a container heated to approximately 600°C that contains specially formulated catalysts (e.g., calcium oxide and / or calcium hydroxide), results in the near complete destruction and removal of PFAS, precursors, and OFCs (volatile and semi-volatile fluorinated degradation products). These compounds are removed by catalyzed degradation and mineralization processes and the fluorine produced sequestered as calcium fluoride bound to the soil minerology, with no HF formed or emitted in the extracted vapor stream.

[0009] HF, whether in vapor form or as a condensate, presents significant hazards due to its unique chemical properties. HF is extremely dangerous even at low concentrations. It can be absorbed through the skin and eyes and can cause damage to underlying tissues and bones. HF can also pose severe respiratory hazards including respiratory irritation and pulmonary edema. Additionally, HF also requires careful design and specialized materials of construction for piping, valves, and vessels as HF attacks glass, ceramics, and many metals. Thus, removal, neutralization or sequestration of HF in the soil matrix or catalyst media without requiring extraction or treatment is particularly desirable and beneficial.

[0010] Thus, the invention, incorporating these processes and mechanisms, provides a flexible method for treatment of PFAS contaminated soil and media that can be configured to meet specific site treatment needs (PFAS mixture and soil type), and requirements (remedial goals and air discharge standards). For example, depending on the concentration, mass and specific nature of the PFAS (e.g., carbon chain length and vapor pressure); the geochemistry of the soil or media (i.e., how much calcium carbonate is present); and the remedial and vapor discharge treatment standards, the following configurations of the technology could be used (the following examples are for illustrative purposes and not meant to describe all of the various scenarios and configurations possible with the invention):Soil With Low Concentrations of Calcium Carbonates and High Concentrations of PFAS1) Add calcium containing compounds to the soil.2) Place in engineered container or pile and heat to ~400°C.3) Pass extracted vapor through specially formulated catalyst system containing calcium compounds heated to ~600°C.4) Discharge treated vapors to atmosphere.Soil With Low Concentrations of Calcium Carbonates and Low to Moderate Concentrations of PFAS1) Place in engineered container or pile and heat to ~400°C.2) Pass extracted vapor through specially formulated catalyst system containing calcium compounds heated to ~600°C.3) Discharge treated vapors to atmosphere.Soil With Moderate to High Concentrations of Calcium Carbonates and Moderate to High Concentrations of PFAS1) Place in engineered container or pile and heat to -400° C.2) Pass extracted vapor through specially formulated catalyst system containing calcium compounds heated to ~600°C.3) Discharge treated vapors to atmosphere.Soil With Moderate to High Concentrations of Calcium Carbonates and Low Concentrations of PFAS1) Place in engineered container or pile and heat to ~400°C.2) Direct discharge of extracted vapors or pass extracted vapor through granular activated carbon or other sorptive media.3) Discharge vapors to atmosphere.

[0011] This research also indicates that complete treatment of any PFAS and fluorinated compounds in the soil can be economically and effectively achieved at temperatures substantially lower than traditional thermal remediation methods such as incineration and rotary kilns, which typically heat soils to temperatures near to or in excess of 900°C, by incorporating specially formulated catalysts mixed directly into the soil and / or incorporated into the extracted vapor conveyance and treatment system. Incineration and rotary kiln systems have the added burden of requiring a quench and acid neutralization system for removing any HF formed during the treatment of PFAS that is present in the vapor stream and the subsequent requirement for treatment of the liquid blowdown from the neutralization system, which can contain PFAS. The present invention eliminates the need for a quench and acid neutralization system to remove HF from the vapor stream, as it relies on the naturally present calcium compounds in the soil, or adds calcium compounds to the soil, and / or utilizes specially formulated catalysts containing calcium compounds in a vapor treatment system to sequester the fluorine produced from the degradation of the PFAS and OFCs thereby preventing the formation of HF.

[0012] The present invention discloses a system, device and method for effective, economical, and sustainable treatment of PFAS and OFCs utilizing electrically powered, or fossil fuel-fired, thermal conduction heaters or other methods, to heat soil to between 250°C and 550°C and incorporating specially formulated catalysts mixed directly into the soil and / or incorporated into the extracted vapor conveyance and treatment system. While electrically powered thermal conduction heaters are presented herein as the preferred embodiment for the primary source of heating to raise the temperature of the soil or other media contaminated with PFAS and OFCs, other heating sources including vessels or casings wrapped with electrically powered induction coils, or fossil fuel-fired heaters including natural gas, propane, diesel, or fuel oil fired heating systems, may be used to heat the contaminated media.

[0013] U.S. Patent Publication 2004 / 0228690 by Stegemeier et al., U.S. Pat. No. 6,881,009 by Stegemeier et al., U.S. Pat. No.7,004,678 by Stegemeier et al., U.S. Pat. No. 7,534,926 by Stegemeier et al., U.S. Pat. No. 8,562,252 by Baker et al., andU.S. Pat. No. 8,348,551 by Baker et al., the entirety of each is herein incorporated by reference as if fully set forth herein, describes systems and methods for heating contaminated soil.BRIEF DESCRIPTION OF DRAWINGS

[0014] The detailed description of embodiments refers to the accompanying figures, which depict illustrative embodiments:

[0015] FIG. 1 is a flow chart of an illustrative PFAS remediation method;

[0016] FIG. 2 is an overview of the in situ and ex situ PFAS remediation methods;

[0017] FIG. 3 depicts an electrically powered thermal conduction heater;

[0018] FIG. 4 depicts a side view of an in situ thermal PFAS treatment system in accordance with the embodiment of the invention;

[0019] FIG. 5 depicts a top view of a contaminated media portion of an in situ thermal PFAS treatment system in accordance with the embodiment of the invention;

[0020] FIG. 6 depicts an overview of an ex situ engineered pile PFAS treatment system in accordance with the embodiment of the invention;

[0021] FIGs. 7A and 7B depict side views of an ex situ engineered pile thermal PFAS treatment system incorporating, respectively, separate and co-located heaters and vapor extraction wells in accordance with the embodiment of the invention;

[0022] FIG. 8 depicts an overview of an ex situ thermal PFAS container treatment system in accordance with the embodiment of the invention;

[0023] FIGs. 9A and 9B depict perspective and side views respectively of an ex situ container thermal PFAS treatment system in accordance with the embodiment of the invention with horizontal heaters;

[0024] FIG. 10 depicts a side view of an ex situ thermal PFAS container treatment system in accordance with the embodiment of the invention with vertical heaters;

[0025] FIG. 11 depicts a vapor treatment system incorporating a thermal catalyst for PFAS treatment inside a heated manifold pipe in accordance with the embodiment of the invention;

[0026] FIG. 12 depicts a table demonstrating the results of thermal treatment of target PFAS at 250 °C, 350 °C, and 500 °C, all for 1 week of residencetime at the respective treatment temperatures, in accordance with an embodiment of the invention;

[0027] FIG. 13 depicts a table demonstrating the results of thermal treatment on target PFAS precursors at 250 °C, 350 °C, and 500 °C, all for 1 week of residence time at the respective treatment temperatures, in accordance with an embodiment of the invention;

[0028] FIG. 14 depicts a mass spectrum of air extracted from soil heated to 497°C during lab scale treatment studies demonstrating the presence of short chained PFAS and PFAS degradation products (arrows and associated chemical structures), in accordance with an embodiment of the invention;

[0029] FIG. 15 depicts pie charts demonstrating the sources of fluorine in soil before and after a lab scale mineralization test, where the amount of fluorine is equivalent, indicating closure of the fluorine mass balance and accounting for and demonstrating the fate of 100% of the starting fluorine in the post thermal analyses, in accordance with an embodiment of the invention; and

[0030] FIG. 16 depicts a schematic showing a device for treating soil and sediment impacted with PFAS, in accordance with an embodiment of the invention.DETAILED DESCRIPTION OF THE DRAWINGS

[0031] The invention herein comprises systems, devices, and methods for the remediation of per- and polyfluoroalkyl substances, PFAS, including their precursors and degradation compounds such as volatile, semi-volatile, and non-volatile fluorinated alkene and alkane organic chemicals, and OFCs, in media through heating the media using electrically powered thermal conduction heaters or other methods, to temperatures between approximately 250°C and 550°C. The media impacted with PFAS and OFCs that requires treatment can be heated and treated either in situ, or ex situ in engineered piles or containers. The invention incorporates the use of specially formulated catalysts to facilitate the degradation and mineralization of PFAS and OFCs and subsequent sequestering of the fluorine produced from mineralization as immobile ionic fluoride compounds (e.g., calcium fluoride), thereby eliminating the emission of fluorinated compounds including hydrogen fluoride (HF), in the extracted vapor stream. The catalysts can either be mixed directly in the media that is being heated and / or incorporated into specially designed components of a vapor conveyance and treatment system to treat the vapor stream that is formed and extracted from the mediaduring heating and treatment. In addition to treatment of soil, the invention is also applicable for the treatment of sediments, sludges, soil washing fines, waste-water solids, bio solids, and granular activated carbon (GAC) or other sorptive media, and other solids or semi-solid media contaminated with PF AS and OFCs. As such, the present invention discloses a method that can be used for thermally remediating PFAS and OFCs through the use of specially formulated catalysts as a means for environmental remediation, though the invention’s utility is not confined to such tasks.

[0032] The invention herein achieves significant enhancements in the thermal remediation of PFAS and OFCs at temperatures between approximately 250°C and 550°C. For example, conventional thermal remediation of PFAS and OFCs by incineration or rotary kilns or similar technologies target temperatures >900°C for the remediation of soil and other porous media (e.g., sediments, soil washing fines, sludges, GAC, sorptive media, etc.), to effectively degrade, remove, and destroy PFAS and OFCs sufficiently to achieve cleanup standards. Through the use of the invention’s heating technology (e.g., electrically powered thermal conduction heaters or other heating methods), design specifications (i.e., heater designs and spacings, engineered pile systems, and heating durations), and specially formulated catalysts, effective and sufficient degradation, removal, and destruction of PFAS and OFCs can be achieved at substantially lower temperatures, thereby reducing time, power usage, off-gas treatment requirements, and other related design elements, resulting in lower costs for treatment and improved sustainability.

[0033] Because PFAS and OFCs include thousands of individual compounds and current soil, water and vapor analytical methods can only identify and quantify approximately 100 of them (i.e., “target PFAS”), and regulatory agencies are currently only focused on a handful of these, there is a need for treatment systems that can remove and destroy both target PFAS as well as the non-target PFAS, including OFCs, that one day may be targeted and regulated (i.e., the need to achieve complete treatment of all PFAS and OFCs). Unlike conventional thermal methods for treating PFAS impacted media, the invention described herein provides complete treatment of all PFAS and OFCs in the media and the extracted vapor stream through the following mechanisms: (1) thermal mineralization where the PFAS and OFCs are completely broken down to inorganic F, HF, CO2, CO, SO2, SO4, and H2O; (2) thermal degradation where the PFAS and OFCs are broken down to shorter chained compounds such asvolatile and semi-volatile fluorinated alkenes and alkanes which are then removed from the media via volatilization and entrainment in the extracted vapors; (3) sequestering of the fluorine produced as a result of degradation and mineralization of the PFAS and OFCs by naturally occurring or added inorganic compounds such as calcium carbonates as immobile ionic compounds such as calcium fluoride that are insoluble and bound to the mineral surfaces of the soil or media; and (4) treatment of any PFAS and OFCs in the vapor stream extracted from the media using specially designed and heated catalyst media to degrade, mineralize, and sequester the fluorine as immobile ionic compounds; such that both the media and the vapor effluent discharged from the invention contain virtually no or substantially reduced and regulatory acceptable concentrations of PFAS, OFCs, and HF.

[0034] The proposed invention includes the following general steps and processes to achieve complete treatment of all PFAS and OFCs: (1) if required, calcium compounds are mixed into the soil (or other solid media requiring treatment); (2) heater wells are installed in the subsurface or above grade engineered piles or containers; (3) then, the targeted media is heated to at least the applicable boiling point of water (typically, but not necessarily 100°C) and water is removed by boiling and extracting steam to dry-out the media; (4) continued heating of the media after water removal to achieve the desired target treatment temperature (typically, 250°C to 550°C); 3) next, extraction of air, PFAS and OFC vapors and steam during heating; (5) removal of steam from the vapor stream produced during heating to 100°C and dry-out of the media via cooling and condensation; (6) collection and treatment (if required) of the steam condensate; (7) treatment of the dry air and vapors with either a heated thermal catalyst, if required, thermal oxidizer, sorptive media such as GAC, or combination of the aforementioned; and (8) if required, removal of HF and any other acid gases formed by the process using an acid gas scrubber and neutralization system such that the produced vapors and aqueous stream can be safely discharged. These steps can be used to treat soil and other solid or semi-solid media impacted with PFAS and OFCs either in situ or ex situ in specially designed and engineered piles and containers. While some embodiments of the invention are used to treat contaminated soil, the invention can be used in a variety of different media of different compositions. Various catalysts have been proposed and investigated in the literature including calcium oxide (CaO), calcium carbonate (CaCOs), calcium hydroxide (Ca(OH)2), birnessite (nominally MnO2*nH2O),and others. Depending on the embodiment, catalysts might be chosen from the list comprising, but not limited to, calcium oxide, calcium carbonate, calcium hydroxide, bimessite, zero valent metals (e.g., iron, zinc, titanium), metal oxides and sulfides, and aluminosilicates, or combinations thereof. The catalyst or mixture of catalysts can be mixed into the media being treated prior to heating to facilitate the PFAS removal efficiency and sequestering of fluorine produced to eliminate production of HF. In many instances the in situ and ex situ systems will incorporate electrically powered thermal conduction heaters or other media heating methods; vacuum extraction wells to remove air, PFAS and OFC vapors, and steam; air inlet wells or other air inlet components where applicable, temperature monitoring sensors; insulation to minimize heat loss and ensure uniform heating and treatment; vapor barrier to ensure effective capture and removal of PFAS and OFC vapors; and a vapor extraction and treatment system incorporating some or all of the following components: (1) extraction blowers, (2) heat exchanger and cooling system to cool the vapor stream and condense extracted steam, (3) condensate collection and if required, treatment system; (4) thermal catalyst system, thermal oxidizer, and / or GAC or other sorptive media to treat and remove PFAS and OFCs from the dry vapor stream; (5) acid gas scrubbing (if required), and (6) Programmable Logic Controller (PLC) systems and other sensors and equipment to monitor and control heating and treatment processes. Because of the physical and chemical properties of PFAS, namely their thermal stability and very low vapor pressures and high boiling points, very little if any PFAS are removed during the media drying process and end up in the steam condensate collected.

[0035] As described herein, the proposed invention is substantially different and an improvement over existing thermal treatment methods such as, but not limited to: (1) incineration using direct or indirect heating via a fuel source and burner to produce a flame, or indirect heating using induction heating, or an alternative heating method depending on the needs of the embodiment, and (2) smoldering where a fuel source is mixed into the media and ignited under controlled conditions, either in situ or ex situ, with regulated air flow to sustain a bum front through the targeted volume, and where temperatures around or greater than 900°C are used to mineralize and degrade the PFAS present in the media.

[0036] Furthermore, the proposed invention is substantially different and an improvement over other low or moderate temperature thermal treatment methods thatincorporate heating media to temperatures in the range of approximately 225 °C to 440°C using thermal conduction heaters, or such alternatives as appropriate for a given embodiment to: (1) reduce total organic carbon (TOC) in the media and surface effects between the PFAS and TOC, resulting in evaporation of the PFAS; (2) capture of evaporated PFAS through vapor recovery; (3) removal of PFAS from the vapor stream by cooling and condensing; (4) addition of steam to aid in the capture and removal of the PFAS; (5) production of a concentrated aqueous PFAS solution; and (6) treatment of the concentrated aqueous PFAS solution by ElectroOxidation or other methods (Patent Pub. No. US 2019 / 03214847 Al). The significant problem with the existing methods is that they do not provide complete treatment of non-polar volatile or semivolatile fluorinated alkenes or alkanes that may be produced during thermal treatment of the media and that may be present in the vapor stream. These existing methods are primarily applicable to removal and treatment of longer carbon chain, polar fluorinated compounds that may be present in the extracted vapor. The volatile and semi-volatile fluorinated alkenes and alkanes will persist in the vapor stream due to their relatively high vapor pressures and non-polar properties and not be effectively removed by this method, thereby resulting in incomplete treatment and their potential discharge to the atmosphere.

[0037] The proposed invention is a significant improvement over existing thermal methods for treatment of media impacted with PFAS and OFCs (such as incineration, smoldering, or other thermal conduction heating methods), as it: (1) uses lower treatment temperatures (approximately 250°C to 550°C) thereby reducing energy needs; (2) does not produce dust or ash that must be removed from the extracted vapor stream and that requires subsequent treatment or disposal; (3) incorporates specially formulated catalysts either mixed directly into the media and / or incorporated into treatment of the extracted vapor stream to achieve complete treatment of all PFAS and OFCs, including non-polar volatile and semi-volatile alkenes and alkanes; (4) does not produce and emit Products of Incomplete Combustion or Degradation (PICs or PIDs), that may include shorter chain PFAS, OFCs or other fluorinated compounds that could broadly be considered PFAS and that have adverse effects on the environment, climate, or human health; (5) does not involve the removal of PFAS from the vapor stream extracted from the heated media by cooling and condensation and wet scrubbing, resulting in a liquid waste stream containing PFAS and OFCs requiring additionaltreatment and disposal; and (6) significantly reduces or eliminates the production and emission of HF in the vapor stream eliminating the need for expensive acid gas neutralization systems, that in themselves produce a waste stream requiring treatment.

[0038] The invention herein comprises the use of one or more heating devices arranged in a suitable pattern determined by the needs of a target volume if in- situ, or configuration of a treatment pile or container if ex-situ, to heat the media or other solid media to temperatures between approximately 250°C and 550°C depending on the conditions of the target volume, the physical and chemical properties of the specific PFAS and OFCs targeted, and the remedial media clean up concentration goals. The invention also includes a vapor extraction system for the removal of air, steam, and contaminant vapors formed during heating the media and a vapor treatment system for the removal of any PFAS, OFCs, and acid gases (if required) present in the extracted vapors. The invention also incorporates specially formulated catalysts mixed into the media and / or incorporated into components of the vapor conveyance and treatment system to promote the mineralization and degradation, of the PFAS and OFCs and sequestration and removal of the fluorine, such that PFAS and OFCs are destroyed and HF is eliminated from the extracted vapor stream. In some embodiments, the invention is comprised of a plurality of heaters wherein the heaters are at least partially embedded into the ground, soil pile, or soil treatment container in, depending on the embodiment, a pattern configured to optimize heat distribution and / or uniformity of heating, or to otherwise ensure adequate heating and remediation of the contaminated target volume. Where the contaminant is not uniformly distributed in the contaminated target volume in in-situ applications, the heaters may be arranged to address the non-uniformity or in some embodiments moved as part of treatment. In some embodiments of the invention, the heaters are comprised of rods made of a material configured to provide some electrical resistance and generate an embodiment-appropriate amount of heat when a conducting wire is connected to the heater rod and an electrical current is passed through the rod. In other embodiments, the heater element may consist of a wire made of a material configured to provide some electrical resistance and generate an embodiment-appropriate amount of heat when a conducting wire is connected to the heater element wire and an electrical current is passed through heater element wire. In other embodiments, the heater may consist of a fuel gas fired burner that directs the hot exhaust from the burner through an inner pipe placed in an outer pipe to circulate thehot exhaust gases and heat the outer pipe and surrounding media. As the foregoing should suggest, the invention can function with a variety of heating methods, including others not listed. This heat then radiates into the target volume at temperatures based on the needs of the embodiment, typically, but not exclusively, between approximately 250°C and 550°C. The heaters may be powered in a variety of ways, whether through a local power grid, fossil-fuel fired generator, source of fuel gas, or some other locally available power source. In some embodiments of the invention, the temperature targeted for treatment and duration of treatment are customized to achieve the required remedial goals for the specific PFAS and OFCs targeted for treatment and the nature of the media. For example, heating a soil or solid to 400°C for 7 days may be as effective at achieving the remedial goals as heating the soil or solid to 500°C for 3 days, whereas the costs and energy usage for heating to 400°C for 7 days may be less than the costs and energy usage for heating to 500°C for 3 days. Thus, the economics and sustainability of the invention can be optimized for each specific media treatment application based on the characteristics of the media (e.g., water content, organic fraction content, minerology, etc.), specific PFAS being targeted for remediation, and the required remedial goals.

[0039] As described herein, the invention in some embodiments may include the addition of a catalyst or mixtures of catalysts to the soil or other media to promote the mineralization and degradation of the PFAS and OFCs and sequestration of the fluorine within the media. Various catalysts have been proposed and investigated in the literature including calcium oxide (CaO), calcium carbonate (CaCOa), calcium hydroxide (Ca(OH)2), bimessite (nominally MnCh'nFhO), and others. Depending on the embodiment, catalysts might be chosen from the list comprising, but not limited to, calcium oxide, calcium carbonate, calcium hydroxide, bimessite, zero valent metals (e.g., iron, zinc, titanium), metal oxides and sulfides, and aluminosilicates, or combinations thereof. For example, in thermal treatability laboratory studies reported by Wang et al. (2013) and Riedel et al. (2021), vaporized PFAS compounds (e.g., PFOS and fluorotelomer alcohols), showed degradation rates of 60% to >95% for treatment temperatures between 350°C and 550°C depending on the calcium containing compound and mixture percentage present in the reactor. In addition, these studies showed that the presence of calcium prevented the release of short and longer-chained PFAS in emissions (Wang et al., 2013) and reduced the production of secondaryfluorinated compounds (Riedel et al., 2021). In recently completed laboratory studies, approximately 100% of the volatized fluorinated compounds formed and extracted from heating soil spiked with PFOS to 350°C were removed by passing the extracted vapors through a reactor containing a mixture of calcium hydroxide (Ca(OH)2) and heated to 600°C, through a combination of mineralization and likely formation of CaF2 or other inert mineral complexes. The average removal efficiency of PFOS from the soil was >99.5% and less than 0.000005% of the fluorine associated with the spiked PFOS was observed as PFOS in the discharge vapor, indicating the capability of the invention to achieve near complete treatment of PFAS impacted media, as presented by Fortune et al (2023) and LaChance et al (2024).

[0040] As described herein, the invention in some embodiments presents a novel and highly effective and sustainable method utilizing catalysts or mixtures of catalysts including, but not limited to, calcium oxide (CaO), calcium carbonate (CaCO3), calcium hydroxide (Ca(OH)2), bimessite (nominally MnO2«nH2O), zero valent metals (including, but not limited to, iron, zinc, and titanium), metal oxides, metal sulfides, and others for remediating media contaminated with PFAS to very low or non-detectable concentrations, and ensuring that both target PFAS and non-target PFAS including precursors and OFCs, and in addition HF, are effectively treated in the off-gas and not discharged into the atmosphere.

[0041] The catalyst or catalysts can be mixed into the target volume if in- situ or mixed into the media as it is loaded into an ex-situ treatment pile or container either in a dry solid form or as a component of an aqueous mixture. The specific catalyst or mixture of catalysts and percentages of catalyst(s) to media by volume or weight, will vary depending on the specific nature of the media or material being treated, the specific PFAS and OFCs targeted for treatment, and the desired remedial goals.

[0042] The target temperature and heating duration of some embodiments of the invention can be varied and customized depending on the specific nature of the media or material being treated, the specific PFAS and OFCs targeted for treatment, and the desired remedial goals. As such, the invention described herein, may incorporate temperature monitoring sensors into the targeted volume to monitor and track temperatures of the media or other material being treated to ensure adequate and uniform heating.

[0043] In some embodiments of the invention, the vapors extracted from the media can be passed through a specially designed and engineered thermal catalyst to promote the destruction and removal of PFAS and OFCs from the extracted vapor stream, such that the concentrations of PFAS and OFCs in the vapor stream are reduced or negligible and suitable for direct discharge of the vapors to the atmosphere, or discharged with minimal polishing effluent vapor treatment. The thermal catalyst system has the added benefit of effectively sequestering the fluorine produced from the destruction of the PFAS and OFCs as immobile ionic compounds bound to the catalyst media, thereby eliminating the emission and requirement for treatment and removal of HF from the vapor stream. Based on the needs of the embodiment, the catalyst(s) can be heated, typically, but not exclusively, to between approximately 500°C and 800°C using a variety of methods such as incorporation of the specially formulated catalyst as an additive to or coating on the typical catalyst media of a gas-fired regenerative or recuperative thermal oxidizer or electrically heated catalytic oxidizer. In other embodiments, the catalyst(s) can be mixed with or used as a coating on media such as sand or other uniform gas-permeable, thermally stable material and incorporated into a heated container through which the extracted vapors pass. The container can be heated using either electrically powered thermal conduction heaters or commercially available cartridge heaters or immersion heaters inserted into the catalyst media or other heating elements wrapped around the catalyst media container. In other embodiments, the catalyst container is constructed of electrically conductive material and electrically heated using induction heating coils placed around or inside the container. Extraction piping, catalyst container(s) and related hardware modules would be provided with insulation and jacketing for thermal conservation and personnel protection, as appropriate to their operating temperature, position in the treatment train, and personnel safety considerations.

[0044] In some embodiments of the invention, the catalyst is incorporated as a treatment step of the vapor treatment system or in other embodiments it is incorporated into the vapor conveyance system, or in other embodiments a combination of both are utilized. In some embodiments of the invention, the exhaust vapors from the thermal catalyst system can be discharged directly to the atmosphere, while in other embodiments the exhaust vapors from the catalyst system are directed to a GAC or other sorptive media system, or thermal oxidizer, or acid gas scrubber, or a combinationof the aforementioned, for additional polishing treatment before discharge to the atmosphere.

[0045] In some embodiments of the invention, extracted contaminated vapors are conveyed to or through the catalyst bed via a heated and insulated piping manifold. The vapor conveyance manifold network may be heated using so-called “insertion heaters” or other suitable heating devices, including indirectly heated packed ceramic beds, to raise the interior temperature of the vapor conveyance piping network to approximately 500°C to 700°C, or to approximately 250°C to 550°C in the presence of the catalyst media, depending on the conditions of the target volume, the physical and chemical properties of the specific PFAS and OFCs targeted, and the remedial media clean up concentration goals, such that the residual PFAS compounds in the extracted vapor stream may be degraded, decomposed or destroyed within the heated vapor conveyance piping network. The vapor extraction flow rate and conveyance piping network are designed to allow for adequate retention time within the hot manifold pipe for the degradation or decomposition of the PFAS compounds; however, it is noted that at such elevated temperatures, degradation or decomposition will proceed rapidly. (Laboratory or bench testing of specific PFAS compounds may be necessary to confirm appropriate retention time vs. temperature curves to demonstrate adequate destruction for regulatory approval, with or without requiring subsequent effluent treatment.) The hot vapors are then rapidly cooled with water in a quench vessel, followed by neutralization of residual HF in an acid-gas scrubber system if required, after which the treated vapors may be discharged to the atmosphere without further treatment. The neutralized aqueous stream will contain no or de minimis concentrations of PFAS and can be safely discharged using standard means.

[0046] FIG. 1 is a flow chart of an illustrative PFAS remediation method. The method 100 may be comprised of a series of steps. The invention may be comprised of the following general steps and processes to achieve complete treatment of all PFAS and OFCs: (1) in step 101, which is optional depending on the needs for treatment, calcium compounds may be mixed into the soil or contaminated media (or other solid media requiring treatment) if required or beneficial; (2) in step 102, heater wells are installed in the subsurface or above grade engineered piles or containers; (3) in step 103, the targeted media is heated to at least the applicable boiling point of water (typically, but not necessarily 100°C) and water is removed by boiling and extractingsteam to dry-out the media; (4) further in step 103, continued heating of media after water removal to achieve the desired target treatment temperature (typically, 250°C to 550°C); (5) in step 104, extraction of air, PFAS and OFC vapors, and steam during heating; (6) in step 107, removal of steam from the vapor stream produced during heating to 100°C and dry-out of the media via cooling and condensation; (7) further in step 107, collection and treatment (if required) of the steam condensate; (8) in steps 105 and 106, treatment of the dry air and vapors with either a heated thermal catalyst, thermal oxidizer, sorptive media such as GAC, or combination of the aforementioned; and (9) further in steps 105 and 106, removal of HF and any other acid gases formed by the process using an acid gas scrubber and neutralization system such that the produced vapors and aqueous stream can be safely discharged. Notably, steps 105 and 106 can be interchanged with 107 and / or performed cyclically, repeating the process as needed to treat the contaminants. These steps can be used to treat soil and other solid or semi-solid media impacted with PFAS and OFCs either in situ or ex situ in specially designed and engineered piles and containers. While some embodiments of the invention are used to treat contaminated soil, the invention can be used in a variety of different media of different compositions. A catalyst or mixture of catalysts can be mixed into the media being treated prior to heating to facilitate the PFAS removal efficiency. In many instances the in situ and ex situ systems will incorporate electrically powered thermal conduction heaters or other media heating methods; vacuum extraction wells to remove air, PFAS and OFC vapors, and steam; air inlet wells or other air inlet components where applicable, temperature monitoring sensors; insulation to minimize heat loss and ensure uniform heating and treatment; vapor barrier to ensure effective capture and removal of PFAS and OFC vapors; and a vapor extraction and treatment system incorporating some or all of the following components: (1) extraction blowers, (2) heat exchanger and cooling system to cool the vapor stream and remove steam, (3) condensation collection and if required, treatment system; (4) thermal catalyst system, thermal oxidizer, and / or GAC or other sorptive media to treat and remove PFAS and OFCs from the dry vapor stream; (5) acid gas scrubbing; and (6) PLC and other sensors and equipment to monitor and control heating and treatment processes. Because of the physical and chemical properties of PFAS, namely their thermal stability and very low vapor pressures and high boiling points, very little if anyPFAS are removed during the media drying process and end up in the steam condensate collected.

[0047] The step of installing heater wells into the subsurface of the contaminated media can be accomplished by a variety of methods, including, but not limited to, installation of heater wells and / or vapor channels into the subsurface of a remediable area in situ, or the contaminated soil and media may be instead excavated into engineered piles or containers ex situ and the heater wells and / or vapor channels are inserted therein or they may already be present and the contaminated soil and media is inserted around them. In other embodiments, combinations of those may be employed, such as in-ground containers or the installation of barriers in the subsurface if appropriate.

[0048] The variable steps of removing the PFAS from the recovered vapor stream can employ conventional methods such as sorptive media (such as activated carbon or similar components) or destructive technologies such as thermal oxidation, but can also involve removing the PFAS using one or more specially configured catalysts. Depending on the nature of the PFAS contamination, one, both, or a hybrid of the foregoing approaches may be employed. For example, some embodiments may first pass the vapor stream through sorptive media, then employ thermal oxidation, and finally utilizing a catalyst. On the other hand, other embodiments may first utilize a catalyst, and then employ thermal degradation to further remove any remaining contaminants. Ultimately, factors such as the treatment configuration and demands will play an important role in determining which removal means are utilized.

[0049] FIG. 2 is an overview of the in situ and ex situ PFAS remediation methods. In FIG. 2 we see two variants of possible configurations of the system 200 to treat contaminated media; an engineered pile (ex situ) 202 (designated IPTD) and soil- inserted (in situ) 203 (designated ISTD) variants of the PFAS remediation method. As is demonstrated therein, there are one or more vapor channels 204 configured to capture and channel vaporized water (steam), as well as one or more heaters inserted into the media being treated. In both cases, the positioning of the heaters and vapor channels / pipelines depends on the shape of the media being treated, the contaminant being treated, and any other constraints or limitations of the system 200 such as, but not limited to, available power and treatment space. Regardless of whether the in situ or ex situ method is utilized, the vapor is channeled into a condenser 206 to form a condensate (water) 208 and a vapor 210. The system 200 may feature a hot by-pass 212 systemallowing certain vapors to cycle through or around the condenser. In some embodiments, the vapor is channeled into specially formulated thermal catalytic media 214 and / or conventional thermal oxidation or other catalytic means to break down the PFAS and other contaminants; these may reach temperatures at or around 600°C. Simultaneously, the condensate is channeled into similar treatment areas 216 where it can similarly be channeled into specially engineered and formulated aqueous treatment or sorptive systems to breakdown or remove the PFAS and other contaminants, then discharged 218 from the system 200. On the vapor side of the system 200, once the vapor has been sufficiently treated it may be passed through a scrubber 220, then discharged 222 from the system 200 through an extraction blower 224. Some examples of catalysts in the catalytic media 214 that may be appropriate include but are not limited to, calcium oxide, calcium carbonate, calcium hydroxide, birnessite, zero valent metals (e.g., iron, zinc, titanium), metal oxides and sulfides, and aluminosilicates, or combinations thereof.

[0050] In some embodiments, the system 200 for the remediation of contaminants from media is comprised of: a contaminated media; one or more heaters wherein the heaters are inserted into the contaminated media and configured to heat the contaminated media to temperatures of 250°C to 550°C.

[0051] In a preferred embodiment the one or more heaters are electrically powered or fossil fuel-fired and are inserted into the contaminated media such that the heaters can heat the entirety of the contaminated media substantially uniformly, though depending on the media and availability of the heaters the heat within the contaminated media may vary during heating. The one or more heaters, depending on the embodiment, may instead comprise vessels or casings wrapped with electrically powered induction coils, or fossil fuel-fired heaters including natural gas, propane, diesel, or fuel oil fired heating systems, may be used to heat the contaminated media. The system 200 may be further comprised of one or more temperature sensors which may be in communicable contact with one or more of the heaters, allowing a controller, whether operated by a user, a computer system, or both, to manually or automatically adjust the heaters to increase or decrease heating in the media. Depending on the number of heaters and needs of a specific embodiment, they may be controlled individually and / or as a group, and may be capable of various ranges of heating depending on the heater chosen. In a preferred embodiment, the heaters are capable ofheating the media to temperatures between 250°C and 550°C, but other embodiments may utilize other ranges.

[0052] The contaminated media itself may be located in a variety of places, and the system 200 may be configured to treat the contaminated media in situ or, in other embodiments, the contaminated media may be collected and placed into an engineered pile or container prior to such treatment ex situ.

[0053] In some embodiments, the system 200 may be further comprised of at least one catalytic media 214 (herein and throughout also referred to as a catalyst) configured to facilitate the degradation and / or mineralization of the contaminants. The catalyst might be chosen from the list comprising, but not limited to: calcium oxide, calcium carbonate, calcium hydroxide, bimessite, zero valent metals (e.g., iron, zinc, titanium), metal oxides and sulfides, and aluminosilicates, or combinations thereof. Exactly which catalyst(s) are chosen may depend on the nature of the contaminant and expected precursors and / or products of reduction. Contaminants treated may include, but are not necessarily limited to, perfluoroalkyl and polyfluoroalkyl substances, their precursors, and the products of remediating such perfluoroalkyl and polyfluoroalkyl substances. The system 200 may, in some embodiments, also be configured to degrade volatile, semi-volatile, and non-volatile fluorinated alkene and alkane organic chemicals.

[0054] For some embodiments, the system 200 may be further configured to sequester certain compounds, such as fluorine and prevent the formation and emission of HF, and / or neutralize certain acidic gases that may be produced during the degradation and destruction of PFAS and its related compounds.

[0055] The invention may, in some embodiments, be further comprised of one or more vapor extraction and treatment systems comprised of one or more components from the list including, but not limited to: one or more extraction blowers 224, one or more heat exchanger and condenser 206 cooling systems configured to cool a vapor stream and remove steam, one or more condensation collection and condensate treatment systems (also referred to as treatment areas 216); one or more thermal catalytic 214 systems; one or more thermal oxidizers; one or more granular activated carbon (GAC) or other sorptive media beds, sometimes referred to as a scrubber 220 or working in tandem therewith; and one or more sensors to monitor and control heating and treatment processes. In other embodiments, the system 200 may be configured to comprise a vacuum extraction well wherein such well is configured to remove air,vapor, and / or steam, and such well may be complemented or further comprised of one or more air inlets. Similarly, in some embodiments, to assist in containing gases, the system 200 may have one or more vapor caps 226, covers, and / or barriers placed over or around the contaminated media to minimize the potential for fugitive emissions. In some embodiments, the vapor cap 226 may include one or more layers of insulating material to minimize heat loss from the heated contaminated media to the surrounding environment.

[0056] FIG. 3 depicts an electrically powered thermal conduction heater 300 for use in the system. Depending on the embodiment, the system may utilize one or more heaters 300. These heaters 300 may take a variety of forms and utilize a variety of power sources, such as, but not limited to, thermal conduction heaters, electrically powered heaters 300 which utilize inherent resistance in wires 302 to generate heat and channel that heat into the surrounding contaminated media 304 for treatment. Variants of the heater 300 may utilize other heating approaches such as, but not limited to, using fossil fuel heated piping, channeling heated water or other fluids through the heater, or other variations. Some preferred embodiments of the invention may utilize one or more electrically powered thermal conduction heaters 300, wherein heat generated by electricity travelling through wiring connected to the heating element, in this example the wire 302, is channeled into the contaminated media 304 to heat it. In some embodiments, the heater 300 is inserted into a heating well 306 wherein the heater 300 is comprised of a length of electrically conductive wire 302 or similar component.

[0057] The electrically conductive component may be a length of wire 302 that enters and proceeds down the length of the heater 300, then turns and returns to the top once it reaches the bottom of said heater 300, usually but not necessarily at or near the bottom of the heating well 306. However, other embodiments may utilize heaters 300 comprised of coils, cartridges or other configurations of the wire or similar component. In the case of electrically powered thermal conduction heaters 300, the temperature can be increased by increasing the current passing through the wire 302. Alternatively, in other embodiments the system may instead rely on other forms of heating such as fuel-fired systems or other heating means, which may be configured differently but ultimately designed to channel heat into the media 304 through a heater 300 inserted into a heater well 306, casing or similar insertion point. For example, some embodiments involving decontamination in a container may rely on heating the wallsor floor of the container at a certain rate and allowing heat to propagate into the contaminated media 304 in the interior.

[0058] FIG. 4 depicts a side view of a portion of the contaminated media portion 400 of an in situ thermal PFAS treatment system 200 in accordance with the embodiment of the invention. As depicted in FIG. 4, one can see a plurality of heaters 300 inserted into the contaminated media 304 at spatially discrete positions such that, in such a configuration, they can heat the contaminated media 304 at a desirable rate. For treatments involving in situ remediation of the contaminated media 304, the system may be configured such that one or more heaters 300 and vapor channels 204 are inserted into a contaminated media 304 directly, positioned such that as the contaminated media 304 is heated by the heaters 300 and the vapor is captured by the vapor pipelines or channels 204 and conveyed elsewhere into the system. If necessary or desirable, some variants may involve placing a cover 226 over the contaminated media 304 to ensure vapor cannot escape directly into the air.

[0059] FIG. 5 depicts a top view of a contaminated media portion 400 of an in situ thermal PFAS treatment system 200 in accordance with the embodiment of the invention. When viewed from the top, some embodiments of the system 200 wherein the system 200 involves embedding the heaters 300 into the ground where the contaminated media 304 is located. In such an embodiment, there are arranged a number of heaters 300 and vapor channels 204 such that the heat is channeled below grade and into the ground 508, or into the page from the perspective in FIG. 5. As is visible in FIG. 5, these heaters 300 may be positioned in a variety of ways, such as periodic intervals to create a grid, or in other patterns to provide optimal heating given the conditions of the site 502 being treated. Other embodiments may call for staggered positionings as necessary. Depending on the nature of heater 300 being used, they may be connected in series or in parallel, or may be each individually connected to its own heat or power source 504, depending on the variant of heater 300. Once heated, the vapors and fluids from the contaminated media 304 are channeled by vapor channels 204 into the rest of the system 506 for decontamination.

[0060] FIG. 6 depicts a perspective view of an ex situ engineered pile variant of the PFAS treatment system 200 in accordance with the embodiment of the invention. FIG. 6 is a depiction of a variant of the system wherein the system treats contaminated media that has been placed into one or more engineered piles 602. As is depicted, a plurality of piles 602 can be used, and the heaters 300 powered by a powersource 504 can be inserted into the piles 602, with vapor channels 204 extracting vapor by extending out of them, though it is not necessarily required that the heaters 300 and extraction means be inserted from different sides; some embodiments may have them using the same side or a plurality of sides to conform to site layout restrictions or to optimize site logistics. The extraction means pulls the steam and vapors from the piles 602 and moves it into the treatment system. From the piles 602, the vapor enters into a heat bypass and / or heat exchanger 212, and then into a condenser 206 which splits the vapor and condensate (water). The latter is pulled into the condensate section by a pump 604, where it is treated in treatment areas 216, and then discharged 218. Meanwhile, the vapor may be pushed into treatment systems by a blower 224 (a blower can also be used to discharge it from the system later on), where it is treated by a scrubber 220 and then discharged 222. In some embodiments, the piles 602 may have a vapor cap 226 or cover designed to keep vapor from escaping.

[0061] In some cases it will not be feasible or desirable for the PFAS treatment to occur in situ so it may instead be preferable to perform the treatment ex situ by first moving the contaminated media from its original location and into containers or engineered piles 602 where it can be treated. As depicted in FIG. 6, the system 200 may be configured to split the vapor and condensate (water) into separate paths for treatment using a condenser 206 and treat them in a variety of ways.

[0062] FIGs. 7A and 7B depict side views of an ex situ thermal PFAS treatment system engineered pile 202 in accordance with the embodiment of the invention. Building off what was depicted in FIG. 6, FIGs. 7A and 7B show a side view of an above grade engineered pile 602 filled with contaminated media 304 to be treated with separate and co-located heaters 300 and vapor channels 204 (extraction and air inlet wells), respectively. As described previously, it is not necessarily inherently required that the pile 602 be entirely above grade. Depending on the embodiment, heaters 300 and vapor channels 204 may be positioned at varying locations within the pile 602 in order to heat the media and capture any vapor. As is depicted, the pile 602 may be covered by a vapor cap 226 or similar means in order to insulate and / or prevent the vapor from escaping into the atmosphere. The exact shape of the pile 602 can vary, as can the orientation of the vapor channels 204 and heaters 300; in some embodiments they may be inserted vertically, horizontally, at other angles, or at some combination of them all. For example, some variants may find it advantageous to have the heaters 300 inserted into the pile horizontally parallel to the grade while inserting the vaporchannels 204 vertically perpendicular to the grade. Some embodiments may feature an under-side cover 700 to prevent the contaminated media 304 from interacting with the ground 702.

[0063] In the case of engineered piles 602 for ex situ remediation, the system may utilize a vapor cap 226 or other form of cover configured to contain the vapor in the pile 602 and ensure it is channeled into the system rather than being allowed to escape into the atmosphere. For example, such vapor cap 226 or cover could be comprised of mineral wool along with a high-temperature tarp and insulation capable of withstanding the heating temperatures of the heaters 300. In some embodiments, lightweight air-entrained concrete, aerogel or other insulating materials or combinations thereof, may be used. Additionally the vapor cap 226 or cover may comprise embodiment-appropriate temperature rated tarps, thermoplastic liner material, sheet metal, concrete, or an enclosing structure, or combinations thereof, to provide an appropriate vapor seal and surface cover.

[0064] FIG. 8 depicts an overview of an ex situ thermal PFAS container treatment system 800 in accordance with the embodiment of the invention. In this depiction, a variant of the PFAS treatment system 200 is depicted wherein the contaminated media 304 is shown in engineered containers 800 that can be transported to and from a treatment facility 802. A party that desired the soil be decontaminated would transport a container 800 to the treatment facility 802, wherein the vapor channels 204 and heaters 300 would be inserted therein or they may already be present in the container 800. Alternatively, treatment containers 800 could be pre-positioned at the treatment facility 802 and loaded from conventional dump trucks or soil transport roll-off containers. The treatment would then proceed as described herein until adequately decontaminated to meet the needs of the user, and then the treatment container 800 would either be emptied or transported away to be emptied at an appropriate off-site location. Depending on the configuration, the containers 800 may have a lid to function as a vapor cap 226.

[0065] FIGs. 9A and 9B depict perspective and side views respectively of an ex situ container 800 thermal PFAS treatment system in accordance with the embodiment of the invention. A variant of the container 800 depicted in FIG. 8 is further detailed in FIGs. 9 A and 9B wherein we see respective perspective and side views of a container 800 constructed to contain contaminated media 304 for treatment using the present invention. Depending on the embodiment the container 800 may be a variety ofconfigurations, such as a container 800 that is configured to be placed on a truck or rail car, or a container 800 that is intended to remain stationary and is loaded and unloaded through a separate mechanism. The system may also have a lid to function as a vapor cap 226. For examples of such an ex situ container 800, someone skilled in the art may review: U.S. Pat. No. 8,562,252 and U.S. Pat. No. 8,348,551.

[0066] FIG. 10 depicts a side view of an ex situ thermal PFAS container treatment system container 800 in accordance with the embodiment of the invention with vertical heaters 300. As described in FIGs. 9A and 9B, the invention may instead be embodied in the form of an above grade container 800 wherein the contaminated media 304 is treated ex situ. Depending on the needs of the embodiment, the vapor channels 204 (extraction and air inlet wells) can be positioned in a variety of locations. In FIG. 10 the vapor channels 204 are positioned near the top of the container 800 to take advantage of the buoyancy of the heated vapor. The variant depicted in FIG. 10 also comprises an under-side cover 700 to prevent contact with the ground 702, as well as a vapor cap 226 to prevent vapors from escaping into the atmosphere.

[0067] As with the in situ or above grade engineered piled embodiments, in the ex situ container 800 embodiment the vapor channels 204 and heaters 300 may be inserted in a variety of ways depending on the needs of the embodiment. For example the heaters 300 may be inserted parallel to the longest dimension of the container 800, or may be inserted perpendicular thereto at regular intervals, a combination of both, or at other angles. The vapor channels 204 can be positioned in the same way, with the vapor channels 204 inserted depending on the configuration of the container 800 and any limitations or goals of the embodiment. For example, some vapor channels 204 may be positioned at the top of the container 800 or inserted from the top in order to take advantage of the vapor’s buoyancy.

[0068] As can be seen, some embodiments of the invention may place the contaminated media 304 in one or more containers 800 for treatment, and in such embodiments, heaters 300 may be inserted into the contaminated media 304, or, depending on the design of the containers 800, they may be attached to the walls or floor of the containers 800 which are then heated from the outside in. Some embodiments may employ a combination of both, heating from the walls or floor and through heaters 300 inserted into the contaminated media 304.

[0069] FIG. 11 depicts a thermal catalyst 214 component for PFAS treatment system contained inside a heated manifold pipe 1100 in accordance with theembodiment of the invention. Depending on the needs of the embodiment, the catalyst 214 may be configured to facilitate the degradation and / or mineralization of the contaminants within the vapor conveyance piping network, vapor channels 204. For some embodiments of the invention, the vapors that are extracted, hereafter referred to as extracted vapors 1102, from the media, whether the media is being treated in situ or ex situ, are channeled into a treatment system 506 that may, in some situations, be comprised of at least a heated and insulated manifold pipe 1100 system containing a PFAS thermal catalyst 214, which reacts with the PFAS in the extracted vapors 1102 to degrade or destroy the PFAS, its precursors, and / or OFCs. From there, the treated vapors 1104 may be passed into additional treatment systems 220, or may be subject to acid gas scrubbing prior to their discharge 222 into the atmosphere, fully treated.

[0070] In some embodiments, the system may heat the contaminated catalytic media such that the contaminants volatize out and are extracted in a vapor stream, which is then passed through a condenser capable of separating the concentrated contaminant stream into a condensate and remaining vapors with any residual contaminants.

[0071] As described herein, the invention in some embodiments may also include the addition of a catalyst 214 or mixtures of catalysts 214 to the soil or other media to promote the mineralization, degradation, and inert bonding of the PFAS and OFCs within the media. Various catalysts 214 have been proposed and investigated in the literature including calcium oxide (CaO), calcium carbonate (CaCOs), calcium hydroxide (Ca(OH)2), bimessite (nominally MnO2*«H2O), and others. Depending on the embodiment, catalysts 214 might be chosen from the list comprising, but not limited to, calcium oxide, calcium carbonate, calcium hydroxide, bimessite, zero valent metals (e.g., iron, zinc, titanium), metal oxides and sulfides, and aluminosilicates, or combinations thereof.

[0072] As described herein, the invention in some embodiments presents a novel and highly effective and sustainable method utilizing catalysts 214 or mixtures of catalysts 214 including, but not limited to, calcium oxide (CaO), calcium carbonate (CaCOa), calcium hydroxide (Ca(OH)2), bimessite (nominally MnO2*nH2O), and others for remediating media contaminated with PFAS and ensuring that both target PFAS and non-target PFAS including precursors and OFCs are effectively treated in the offgas and not discharged into the atmosphere.

[0073] FIG. 12 depicts a table demonstrating the results of thermal treatment of PFAS in bench-scale testing performed by the inventors, in accordance with an embodiment of the invention. To prepare, laboratory-scale study evaluations of the thermal treatment of soil or sediment impacted with PFAS were performed. The study was performed on a sample highly impacted with a wide range of PFAS and precursors and considered three treatment temperatures: 250, 350, and 500°C. The impacted soil samples were gradually heated to the target temperatures and held there for 1 week mimicking typical field applications. Significant reductions in PFAS concentrations were demonstrated, especially at treatment temperatures of 350°C and 500°C.

[0074] FIG. 13 depicts a table demonstrating the results from bench-scale testing performed by the inventors of thermal treatment on PFAS for PFAS precursors, in accordance with an embodiment of the invention. Pre- and post-thermal treatment precursor results were determined by subtracting the target PFAS analyte concentrations from the target analyte concentrations measured by the Total Oxidizable Precursor (TOP) assay method. The results shown in FIGs. 12 and 13 indicate that PFAS, including precursors, can be effectively treated and removed from soil by heating to temperatures greater than 350°C.

[0075] The study also demonstrated that fluorine corresponding to the total amount of fluorine found in the PFAS contaminants (TOP assay) is removed from the soil during thermal treatment, as shown in Table 1 below.Table 1

[0076] The above Table 1 demonstrates the results of Fluorine (F) mass balance from lab tests conducted at 350 and 500°C. The soil samples were held at the target temperatures for 1 week. The extractable organic fluorine results in Table 1 showthat more organic fluorine is converted at the higher temperature, and that the PFAS remediation is accompanied by the formation of non-extractable fluorine.

[0077] In order to understand the fluorine transport during the lab test, the 500°C test was repeated, analyzing the outgassing from the soil by directly feeding the extracted gases into a mass spectrometer as shown in FIG. 14. The spectrum is recorded at a soil temperature of 497°C during the heat up phase. Peaks assigned to fluorinated compounds are marked with black arrows. Different ionization techniques were tested. Of these, selective reactive ion (SRI) ionization with 02+ as the reactive ion gave the best sensitivity. One of the mass spectra recorded during the heat up phase is shown in Figure 14. During the test, per- and highly fluorinated aliphatic compounds as well as C3 carboxylic acid precursors were identified in the outgassing from the soil. The assignment of peaks to represent fluorinated species was in some cases not unambiguous since the quadrupole mass spectrometer used does not offer high mass resolution. Assignment is based on reference spectra and repeating peak patterns 50 amu apart (corresponding to -CF2-).

[0078] The subject of mineralization was studied in a subsequent lab study performed by the inventors, using PFOS spiked sand to enable better knowledge of the starting conditions and the total amount of fluorine in the soil. A catalytic reactor (defluorinator) was used for treating the outgasses by heating it to 600°C, which further enhanced the mineralization process.

[0079] FIG. 15 depicts pie charts demonstrating sources of fluorine in a before and after a lab scale mineralization test of a soil sample spiked with PFOS, where the soil was heated to and held at 350°C for one week, with the steam extracted condensed out during boil-off of the water, and once the soil was dry, the dry vapors passed through a catalytic reactor (defluorinator) containing sand and calcium hydroxide and heated to 600°C, in accordance with an embodiment of the invention.

[0080] The results of this lab test revealed the removal mechanisms and fates of the fluorine generated by mineralizing PFAS: (1) fluorine from the mineralization of the PFOS was retained as an insoluble fraction in the soil and catalyst materials, 79%; (2) some volatile hydrogen fluoride (HF) formed was recovered in the alkaline scrubber step, 12%; (3) The presence of insoluble fluorine in the catalyst (45.0%) and HF in the extracted vapor (12.3%), indicates degradation of the PFOS in the soil at 350°C and formation of volatile fluorinated compounds (VFCs), transport of the VFCs out of the soil, and their mineralization in the catalyst at 600°C; (4) somewater-soluble fluoride from the mineralization of the PFOS (HF) was retained in both the soil and the catalyst material, 9%; and (5) a small fraction of 0.007% of the PFOS evaporated and was recovered in the condensate.

[0081] The fluorine mass balance of the mineralization test was closed, total fluorine before thermal treatment was 19.98 mg versus 22.8 mg recovered after thermal treatment. The results are illustrated in FIG. 15. All fluorine present in the test before thermal treatment (19.98 mg) was accounted for after the test (22.79 mg) which is within the experimental and analytical accuracy. 0.0001 % of the PFOS evaporated (thin greyline on right hand diagram), the remainder was converted into water soluble fluoride (found in soil, catalyst and scrubber liquid) or insoluble fluorine (found in soil and catalyst).

[0082] Initial studies by x-ray photoelectron spectroscopy (XPS) of the insoluble fluorine found in the soil and catalyst suggested that it was inorganic in nature, indicating successful mineralization. Given the lack of calcium compounds and other metallic minerals in the sand used as a surrogate for soil and the stainless-steel container, it is likely that the insoluble fluorine in the “soil” was present as chromium fluoride as a result of HF corrosion of the stainless-steel. The catalyst was comprised of clean sand mixed with various calcium compounds, so it is likely that the insoluble fluoride was present in the catalyst as a combination of both calcium fluoride and chromium fluoride.

[0083] The lab scale mineralization tests showcased the potential benefits of the catalytic defluorination reactor in the treatment process. The combination of heating soil to over 350°C and treating the extracted vapors in a heated catalytic defluorinator using specially designed catalysts promoting the complete mineralization of PFAS, precursors, VFCs and other volatile fluorinated compounds, provides an innovative treatment solution for soil, sediment and other media impacted with PFAS. This approach can treat all PFAS (target and non-target) and ensure that harmful fluorinated compounds are not emitted to the atmosphere.

[0084] FIG. 16 depicts a schematic showing a device for treating soil and sediment impacted with PFAS, in accordance with an embodiment of the invention. One embodiment may be comprised of: a heated pile 602 or container 800 with a target soil treatment temperature of at least 350°C based on lab test results, typically 400 to 500°C; a sampling point 1600 at the pile / container outlet; a thermal catalyticdefluorinator comprised of a thermal catalyst 214 or thermal catalytic media; a sampling point 1600 at the defluorinator outlet; following the defluorinator the air is quenched and scrubbed by injecting water and cooled to a lower temperature in a scrubber 220 which may also split the vapor into vapor 210 and condensate 208, and can cycle the condensate back into the scrubber 220 with a nozzle 1602 from the condensate treatment area 216; a sampling point 1600 at the scrubber outlet; the water and condensate is recycled through a quench loop, and if needed, sodium hydroxide is added to maintain a mildly alkaline pH of the injected water to neutralize any acidic gases and if required, efficiently adsorb hydrogen fluoride, then all the water is collected in treatment areas 216 to be available for analysis before being handed over to final discharge 218 or disposal; the scrubbed air is passed through granular activated carbon (GAC) filters 1604; a blower 224 is employed to ventilate the soil and draw the extracted vapor through the vapor treatment system; and a final sampling point 1600 at the blower discharge 222.

[0085] The foregoing examples should be viewed as demonstrations of potential embodiments and are not exhaustive or necessarily conclusive as to the effectiveness of the present invention. In many situations, it may be preferable to utilize mixtures and conditions different from the above or use an embodiment of the invention which an example may have indicated was less effective but may be more optimal in such situation.

[0086] As used herein and unless otherwise indicated, the terms “a” and “an” are taken to mean “one”, “at least one” or “one or more”. Unless otherwise required by context, singular terms used herein shall include pluralities and plural terms shall include the singular.

[0087] Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise”, “comprising”, and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”. Words using the singular or plural number also include the plural and singular number, respectively. Additionally, the words “herein,” “above,” and “below” and words of similar import, when used in this application, shall refer to this application as a whole and not to any particular portions of the application. Many changes, modifications, variations and other uses and applications of the present construction will, however, become apparent to those skilled in the art after considering the specification and the accompanying drawings. All suchchanges, modifications, variations and other uses and applications which do not depart from the spirit and scope of the invention are deemed to be covered by the invention which is limited only by the claims which follow.

[0088] It should be understood that while certain preferred forms, embodiments, and examples of this invention have been illustrated and described, the present invention is not to be limited to the specific forms or arrangement of parts described and shown, and that the various features described may be combined in other ways than those specifically described without departing from the scope of the present invention. The present invention may have additional embodiments, may be practiced without one or more of the details described for any particular described embodiment, or may have any detail described for one particular embodiment practiced with any other detail described for another embodiment.

Claims

What is claimed is:

1. A system for the remediation of contaminants from media, the system comprising: a contaminated media; one or more heaters wherein the heaters are inserted into the contaminated media and configured to heat the contaminated media to temperatures at or below 900°C.

2. The system of claim 1, wherein the system is further comprised of a catalyst configured to facilitate at least one of the degradation or mineralization of contaminants.

3. The system of claim 1, wherein the system is configured to remediate perfluoroalkyl and polyfluoroalkyl substances (PFAS), their precursors, and products of the remediation of the foregoing.

4. The system of claim 1, wherein the system is configured to degrade volatile, semivolatile, and non-volatile fluorinated alkene and alkane organic chemicals related to PFAS and their precursors.

5. The system of claim 1, wherein the system is configured to sequester fluoride and neutralize acid gases produced during the degradation and destruction of the PFAS and related compounds.

6. The system of claim 1, wherein the one or more heaters are positioned to provide uniform heating of the contaminated media.

7. The system of claim 1, wherein the one or more heaters are communicably coupled to one or more temperature sensors and the one or more heaters are configured to adjust their temperatures based on the temperature detected by the one or more temperature sensors, or via manual control inputs.

8. The system of claim 1, wherein the one or more heaters are chosen from one or more of the list comprising electrically-powered thermal conduction heaters, electrical resistance heaters, electrical induction heaters, or fossil fuel-fired thermal conduction heaters.

9. The system of claim 6, wherein the heaters are configured to heat the media to temperatures between 250°C and 550°C.

10. The system of claim 1, wherein the catalyst is chosen from the list comprising calcium oxide, calcium carbonate, calcium hydroxide, bimessite, zero valent metals (e.g., iron, zinc, titanium), metal oxides and sulfides, and aluminosilicates, or combinations thereof.

11. The system of claim 1, wherein the contaminated media is first placed into an engineered pile or a container prior to treatment.

12. The system of claim 1, wherein the contaminated media remains in place and is treated in situ.

13. The system of claim 1, wherein the system further comprises one or more vacuum extraction wells configured to remove air, vapor, and / or steam.

14. The system of claim 1, wherein the system further comprises one or more air inlets.

15. The system of claim 1, wherein the system further comprises one or more temperature monitoring sensors.

16. The system of claim 1, wherein the system further comprises one or more thermal insulators.

17. The system of claim 1, wherein the system further comprises one or more vapor barriers.

18. The system of claim 1, wherein the system further comprises one or more vapor extraction and treatment systems, wherein the vapor extraction and treatment system is comprised of one or more from the list comprising: one or more extraction blowers, one or more heat exchanger and cooling systems configured to cool a vapor stream and remove steam, one or more condensation collection and condensate treatment systems; one or more thermal catalytic systems; one or more thermal oxidizers; one or more granular activated carbon (GAC) or other sorptive media beds; and one or more sensors to monitor and control heating and treatment processes.

19. A method for the remediation of media contaminated with PFAS or OFCs, the method comprising the steps of:installing one or more heaters into the contaminated media where the heaters are configured and positioned to substantially uniformly heat the media; heating the media to at least the boiling point of water based on the conditions of the contaminated media; extracting and treating the resulting steam from the contaminated media; continuing to heat the media to a target temperature between 100°C and 550°C; capturing and extracting vaporized contaminants; treating the vaporized contaminants.

20. The method of claim 19, wherein the method further comprises the step of: condensing, collecting and treating a steam condensate from the media and treating any contaminants therein.

21. The method of claim 19, wherein the treating the vaporized contaminants step is accomplished using at least one of a heated thermal catalyst chosen from the list comprising calcium oxide, calcium carbonate, calcium hydroxide, birnessite, zero valent metals (e.g., iron, zinc, titanium), metal oxides and sulfides, and aluminosilicates, or combinations thereof, or a thermal-catalytic oxidizer, thermal oxidizer, sorptive media, or combination thereof.

22. The method of claim 19, wherein the method further comprises the step of: removing acidic gases formed by the foregoing process using an acid gas scrubber and neutralization system to transfer the acid gases to an aqueous stream.

23. A system for the remediation of media contaminated with PFAS or OFCs, the system comprising: a contaminated media; one or more heaters wherein the heaters are embedded into the contaminated media and positioned to substantially uniformly heat the contaminated media to temperatures between 250°C and 550°C; a vapor extraction system configured to remove contaminant vapors; a vapor treatment system configured to treat contaminants in the contaminant vapors; and a catalyst configured to facilitate the degradation and mineralization of contaminants wherein the catalyst is at least one of, mixed into the contaminated media and / or integrated into the vapor conveyance system and / or vapor treatment system.

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