Managing PFAS in Spent Adsorption MediaManaging PFAS in Spent Adsorption Media Craig Patterson, PE Center for Environmental Solutions and Emergency Response US EPA Office of Research and Development
EPA ORD-Michigan PFAS Action Response Team (MPART) Call on PFAS Destruction Research
May 28, 2020
EPA’s Water Treatment Research
Problem: Utilities lack treatment technology and cost data for PFAS removal Action:
• Gather performance and cost data from available sources (DoD, utilities, industry etc.)
• Conduct EPA research on performance of treatment technologies including home treatment systems
• Update and connect EPA’s Treatability Database and Unit Cost Models • Model performance and cost, and then extrapolate to other scenarios • Document secondary benefits and impact on distribution system
(corrosion) • Evaluate reactivation of granular activated carbon (GAC) • Evaluate incineration of spent GAC and Ion Exchange (IX) resins
Impact: Enable utilities to make informed decisions about cost-effective treatment strategies for removing PFAS from drinking water
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Presenter
Problem: There are many sources of materials that may need to be thermally treated: • Manufacturing wastes • Biosolid sludges • Municipal waste • Obsolete flame retardants • Spent water treatment sorbents - in conjunction with reactivation
What minimum conditions (temperature, time) are needed to adequately destroy PFAS and what are are the products of incomplete combustion?
Action: Conduct bench- pilot- and full-scale incineration studies and modeling to evaluate: • Impact of source material • Impact of temperature on degree of destruction • Impact of calcium • PFAS releases from incineration systems
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Research Needs: Spent Media Needs
• Destruction and removal efficiency? Can the ash be landfilled? Can the GAC be reused?
• Release of off gas (incineration, pollution control devices)? • Mass balance closure to determine the fate of the contaminants?
Chemistry • What PFAS to analyze for? What sampling protocols? • Analytical protocols for air, solid and liquid samples • Effectiveness of conservative tracers?
Source Material • Do spent GAC and IX have different considerations? • Co-treated materials, calcium and other additives? • Size and chemical makeup
Design and Operating Conditions • Reactor type (temperature, residence time) • Reaction zone (flow, movement of materials and gases)
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Evaluation of Incineration of PFAS Residuals from Drinking Water Treatment Plants
Problem: The widespread use of PFAS over the last half century has resulted in contamination of drinking water sources
AEX Resin Tanks Credit: Mark Valentine Lime Sludge Reuse Source: US EPA
Craig Patterson, Marc Mills, and Thomas Speth USEPA ORD, Cincinnati, Ohio
Raghu Ventkatapathy Pegasus Tech. Serv., Cincinnati, Ohio Seyed Dastgheib and Justin Mock Univ. of Illinois Urbana Champaign
Source: EarthJustice
Cement Kiln Source: journal-news.net Cement Kilns in the U.S. Source: US EPA
Action: Anion exchange (AEX) resins are being used by the water industry to remove PFAS. Due to the liability associated with PFAS residuals, many water utilities are incinerating single use resins in cement kilns and waste to energy incinerators instead of regenerating spent resin from water treatment plants
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Impact: Water treatment plant lime softening sludge can be reused as an additive during incineration to enhance the capture of fluorinated compounds from PFAS-laden media
Case Studies from Resin Manufacturers
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Purolite - Select cement kilns (1400-2000 °C) have incinerated waste PFAS resins from Purolite’s production plant in Philadelphia
Cement Kiln Incinerator Source: journal-news.net
Kuraray (formerly Calgon Carbon) - Spent PFAS resins in North Carolina and Colorado were sent to waste-to- energy incinerators in Virginia and California
Waste-to-Energy Incinerator Source: Paul Chaplin, The Patriot-News/file
• Each pound of resin will generate about 12,000 BTUs of energy making resin a sustainable fuel supplement
• Calcium additives can capture fluorine • Hydrogen fluoride capture after incineration is needed
Cement Kiln Incinerators
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Cement kilns are operated under different operating conditions • Gas temperatures of up to ~2,000 °C • Gas residence times of up to 10 seconds • Solid residence time of up to 30 minutes
Source: Purolite presentation and case study. F. Boodoo et al. https://ebcne.org/wp-content/uploads/2018/06/Presentations-EBC-Connecticut- Program-Contaminants-of-Emerging-Concern-Update-on-PFAS.pdf
Cement Kilns in the U.S. Source: US EPA
Lab-Scale Thermal Treatment and Incineration System
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• Anion exchange resins loaded with different PFAS compounds with or without calcium additives are placed in quartz crucibles and inserted into a preheated furnace
• Samples are incinerated (simulating a cement kiln) under constant air flow
• Gas samples are collected in sample bags and sent to certified labs for total fluorine analysis
• Ash residuals are collected and analyzed for total fluorine
CASRN Chain Preferred Name PFAS State Health Advisories
375-22-4 C4 Perfluorobutanoic acid PFBA MN, TX 375-73-5 C4 Perfluorobutanesulfonic aPFBS DE, MA, MN, NV, TX 307-24-4 C6 Perfluorohexanoic acid PFHxA TX 355-46-4 C6 Perfluorohexanesulfonic PFHxS CT, MA, MN, TX
13252-13-6 C6 Perfluoro-2-methyl-3- oxahexanoic acid
HFPO-DA (GenX) NC
Lab-Scale Thermal Treatment and Incineration System
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Incineration of PFAS
• PFAS compounds decompose at < 700 °C and generate different free radicals and unstable fragments of original PFAS molecules, and finally form stable fluorocarbon compounds such as tetrafluoromethane (CF4) and hexafluoroethane (C2F6)
• Higher temperatures (1,000-1,600 °C) may be needed to 1) break very stable C-F bonds without a catalyst (e.g., calcium), 2) complete oxidation reactions, and 3) form HF that requires post-combustion treatment with a caustic medium such as Ca(OH)2
• A conventional cement kiln with a post-combustion treatment unit can effectively incinerate PFAS-laden media and capture HF from combustion flue gas
Sources: Krusic et al. Gas-phase NMR studies of the thermolysis of perfluorooctanoic acid. J. Fluorine Chem. 2005, 126, (11-12), 1510-1516. Watanabe et al. Residual organic fluorinated compounds from thermal treatment of PFOA, PFHxA and PFOS adsorbed onto granular activated carbon (GAC). J. Mater. Cycles Waste Mgt. 2016, 18, 625-630. Wang et al. Effectiveness and Mechanisms of Defluorination of Perfluorinated Alkyl Substances by Calcium Compounds during Waste Thermal Treatment. Environ. Sci. Technol. 2015, 49, (9), 5672-80. Qin et al. Highly Efficient Decomposition of CF4 Gases by Combustion. Conference on Environmental Pollution and Public Health 2010, 126-130. Gossman. The reuse of petroleum and petrochemical waste in cement kilns. Environmental Progress 1992, 11, (1), 1-6.
Evaluation of Incineration of PFAS Residuals from Wastewater Treatment Plants
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Problem: Wastewater sewage sludge contains a wide variety of PFAS compounds. When the biosolids are incinerated, the PFAS may be thermally destroyed or transformed into residual byproducts at various operating conditions:
Variables Value
Gasification Temperature
To be determined by Thermogravimetric Analysis (TGA)
Incineration Temperature
Sample Residence
Radha Krishnan and Don Schupp
Time
USEPA ORD, Cincinnati, Ohio
Univ. of Dayton Research Institute, Ohio
Quantitative Transport and Incineration Testing System
Action: This project evaluates the incineration of a combined mixture of the 10 PFAS compounds with various carbon chain lengths (C6-C12) based on the PFAS composition of domestic sludge. (NIST Standard Reference Material 2781) No. Compound Acronym CAS No. Conc.
(µg/kg) No. Compound Acronym CAS No. Conc. (µg/kg)
C6 Perfluorohexanoic Acid PFHxA 307-24-4 13.0 ± 2.0 C8 Perfluorooctane sulfonamide PFOSA 754-91-6 6.31 ± 0.97
C6 Perfluorohexanesulfonic Acid PFHxS 355-46-4 9.39 ± 1.76 C9 Nonanoic Acid C9H18O2 112-05-0 5.09
C7 Perfluoroheptanoic Acid PFHpA 375-85-9 7.96 ± 1.50 C10 Decanoic Acid C10H20O2 334-48-5 4.76
C8 Perfluorooctanoic Acid PFOA 335-67-1 28.5 ± 3.3 C11 Undecanoic Acid C11H22O2 112-37-8 N/A
C8 Perfluorooctanesulfonic Acid PFOS 1763-23-1 225 ± 41 C12 Dodecanoic
Acid C12H24O2 143-07-7 N/A
Emission Stack Testing of PFAS Residuals from Full-Scale GAC Reactivation Facilities
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When DW treatment plant GAC is reactivated, the PFAS may be thermally destroyed or transformed into residual byproducts • Spent GAC, reactivated GAC and scrubber
water will be analyzed for PFAS • Summa Canister, Modified Method 5 for
Semi-Volatile Organics and PAHs and Modified Method 18 air samples will be collected and analyzed as follows:
Test Parameter EPA Method Carbon dioxide/Oxygen U.S. EPA 3A Volumetric flow rate, moisture U.S. EPA 1, 2, 4 Hydrogen fluoride U.S. EPA 26A Speciated semivolatile organics U.S. EPA 0010/8270D Polar, volatile PFAS compounds Modified U.S. EPA 18 Volatile organic compounds U.S. EPA TO-15
EPA is actively looking for partners for sampling of GAC
reactivation facilities
Multiple Hearth Furnace Access DoorsMultiple Hearth Furnace for GAC Reactivation
Afterburner
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Objectives 1) Improve our understanding of the thermal stability of PFAS 2) Investigate decomposition mechanisms of PFAS-containing wastes during thermal treatment
Design • Using bench-scale systems (TGA, Tube furnaces, etc), evaluate
the incinerability of specific PFAS in mixed wastes streams • Use the individual PFAS data to further evaluate models for
predicting incinerability of other PFAS
Results • Developing protocols for thermogravimetric analysis (TGA)
of individual PFAS and PFAS mixtures in various wastes • Models are being evaluated for their ability to simulate
thermal decomposition of individual compounds
Presenter
Extramural Project (Univ. of North Dakota)
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Thermal Stability and Decomposition of Perfluoroalkyl Substances on Spent Granular Activated Carbon Feng Xiao,* Pavankumar Challa Sasi, Bin Yao, Alena Kubátova, Svetlana A. Golovko, Mikhail Y. Golovko, and Dana Soli Environ. Sci. Technol. Lett. 2020, 7, 343−350 - USEPA ORD Science to Achieve Results (STAR) Program (RD83966; F.X.)

2) Investigate their decomposition mechanisms on spent GAC during thermal reactivation
Design 7 perfluoroalkyl carboxylic acids (PFCAs), 3 perfluoroalkyl sulfonic acids (PFSAs), and 1 perfluoroalkyl ether carboxylic acid (PFECA) in different atmospheres (N2, O2, CO2 and air)
Bench Scale Results • Decomposition of PFCAs such as PFOA on GAC was initiated at temperatures as low as 200 °C • PFSAs such as PFOS, on the other hand, required a much higher temperature (≥450 °C) to decompose • Volatile organofluorine species were the main thermal decomposition product of PFOA and PFOS at ≤600 °C • Efficient decomposition (>99.9%) of PFOA and PFOS on GAC occurred at 700 °C or higher, accompanied by high
mineralization of fluoride ions (>80%)
Presenter
Extramural Project (North Carolina State Univ.)
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Thermal Reactivation of Spent GAC from PFAS Remediation Sites Detlef Knappe, S. James Ellen: North Carolina State University, SERDP Proposal (with EPA cooperation)
Objective: To identify conditions that effectively mineralize PFAS during the thermal reactivation of PFAS-laden GAC
Design: To identify the roles of 1) reactivation temperature, 2) reactivation time, 3) calcium, and 4) pretreatment with base on PFAS fate during thermal reactivation of GAC
Questions to Resolve: • What is the difference in behavior between the acid and salt forms of PFAS
during thermal reactivation of GAC? • What are the roles of calcium and base on the fate of PFAS during thermal
reactivation of GAC? • What are products of incomplete combustion (PICs) in air emissions and on the
reactivated GAC?
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Interactive literature review database that contains over 90 regulated and unregulated contaminants and covers 35 treatment processes commonly employed or known to be effective (thousands of sources assembled on one site)
PFAS treatability data currently available: PFOA, PFOS, PFBA, PFBS, PFDA, PFDoA, PFDS, PFHpA, PFHpS, PFHxA, PFHxS, PFNA, PFOSA, PFPeA, PFPeS, PFPrS, PFTriA, PFUnA, FtS:6:2, FtS:8:2, N-EtFOSAA, N-MeFOSAA, GenX
Considering Treatability Database for remediation
processes including thermal
Presentation Notes
Background on TDB and link. Stress that PFOA and PFOS are now in the TDB. You can find it by Googling EPA TDB
Craig Patterson, PE Center for Environmental Solutions and Emergency Response US EPA Office of Research and Development 513-487-2805 Patterson.Craig@epa.gov
Thomas Speth, PhD Associate Director Center for Environmental Solutions and Emergency Response US EPA Office of Research and Development 513-569-7208 Speth.Thomas@epa.gov
The views expressed in this presentation are those of the individual author and do not necessarily reflect the views and policies of the USEPA. 18
EPA’s Water Treatment Research
Thermal Treatment Research
Cement Kiln Incinerators
Incineration of PFAS
Evaluation of Incineration of PFAS Residuals from Wastewater Treatment Plants
Emission Stack Testing of PFAS Residuals from Full-Scale GAC Reactivation Facilities
ORD Thermal Treatment Research (Cincinnati)
Extramural Project (Univ. of North Dakota)
Extramural Project (North Carolina State Univ.)
PFAS Drinking Water Treatment Information
Contacts