POLY- AND PERFLUOROALKYL SUBSTANCES (PFAS)Big picture, challenges and solutions
May 2016
Dr. Ian Ross
Arcadis UK
© Arcadis 2015
Contents
PFAS News
PFAS Uses & History
PFAS Chemistry
Toxicology
Regulatory Evolution
Analytical Challenges / Advanced Analytical Solutions
Fate and Transport / Site Conceptual Model
Remediation Options
Summary
© Arcadis 2015
• Poly- perfluoroalkyl substances (PFAS) comprises a family of approx. 6,000 fluorinated organic compounds, with PFOS, PFOA representing just two compounds in a complex mixture
• Environmental regulations on PFAS are evolving globally with drinking water standards at ppt/ ng levels and Environmental Quality Standards set very low 0.65 ng/l in Europe
• Aqueous film forming foams (AFFF) contain a complex mixture of PFAS including precursors to PFOS and PFOA which are not currently measured by conventional commercial analysis
• Some PFAS are classed as –persistent organic pollutants (PoPs) and restricted under Stockholm Convention as they are Persistent, Bioaccumulative & Toxic
• PFAS do not biodegrade, but do biotransform to persistent daughter compounds such as PFOS and PFOA which are water soluble and mobile in groundwater so can form very large plumes
• Historically chemical analysis has only focused on a very limited number of PFAS compounds characterized in a few PFAS products
• Remediation has been limited to incineration or stabilisation of soils and pump and treat with GAC for PFOS/PFOA
• Arcadis employs advanced analytical tools to measure entire PFAS mass and unique remediation solutions to destroy PFAS on site or in situ
PFASAccelerating Emergence as Global Contaminants
© Arcadis 2015
PFAS News 2015 / 2016
Detections of PFAS in drinking water has caused spiraling regulatory concern
© Arcadis 2015
https://ing.dk/artikel/forskere-alle-advarselslamper-blinker-fluor-stoffer-163759
Scandinavian News 2013
© Arcadis 2015
https://ing.dk/artikel/hver-tredje-svensker-drikker-vand-med-skadelige-fluorstoffer-171434
Scandinavian News 2013
© Arcadis 2015
https://ing.dk/artikel/derfor-blev-fluorstoffer-i-drikkevandet-en-af-sveriges-vaerste-miljoesager-
170652
Scandinavian News 2014
© Arcadis 2015
https://ing.dk/artikel/giftige-fluorstoffer-fundet-i-grundvandet-170585
Scandinavian News 2014
© Arcadis 2015
Multiple and Varied PFAS Uses
Examples of Common Uses:
• Consumer Products
• Oil and water resistant finishes on paper, textiles, carpeting, cookware
• Aqueous film forming foams (firefighting)
• Electroplating mist suppressants
• Semiconductor manufacture
• Aerospace and electronics applications
© Arcadis 2015
Major Locations of PFAS Contamination
• Dept. of Defense Sites
• Refineries
• Large Rail Yards
• Chemical Facilities
• Commercial and private airports
• Municipal Fire Training Areas
• Landfills
• Fire Stations
• Plating Facilities
• Biosolids land application
© Arcadis 2015
Historical Perspective on PFAS
2009: The Stockholm Convention classes PFOS as a Persistent Organic Pollutant and add it to Annexe B to restrict it’s use.
2006: Eight major manufacturers commit to phase out PFOA by 2015 as part of U.S. EPA PFOA Stewardship Program
2013: After 7 years of research, C8 Science Panel determines probable link between PFOA exposure with ulcerative colitis, high cholesterol, pregnancy-induced hypertension, thyroid disease, and kidney and testicular cancer.
1938: Roy Plunkett discovers polytetrafluoro-ethylene (PTFE)
1954: Production of first PTFE-coated, non-stick cookware.
1949: Products containing PTFE first used for coatings of pipes and leak proofing of pipe connections.
1956: Products
containing
perfluorooctane
sulfonic acid (PFOS)
become a popular
treatment for
clothes, carpets,
and furniture.
1968: U.S. Navy develops first PFAS-containing firefighting foams known as AFFF in response to catastrophic ship fires.
2008: The European Food Safety Authority establishes “tolerable daily intake” for PFAS.
1997: PFOS ubiquitously detected in blood bank samples from non-occupationally exposed people around the world
1978: Manufacturers become aware of C8 PFAS in blood of their manufacturing workers
2002: The primary global manufacturer of PFOS phases out PFOS production and related chemistries
© Arcadis 2015
Recent Acceleration of Attention on PFAS
May 2015: Hundreds of prominent scientists and professionals sign on to the Madrid Statement, urging a complete move away from PFAS chemistry.
January 2016: Manufacturing facility in Hoosick Falls, NY named first PFAS-related Superfund site for PFOA-contaminated drinking water
2015: Phase-out of PFOA completed by eight leading manufacturers as part of US EPA Stewardship Council.
October 2015: A manufacturer was found liable for a woman’s kidney cancer in its first of 3500 personal lawsuits related to PFOA contamination of drinking water near a manufacturing facility in Parkersburg, WV.
2015: U.S. EPA UCMR3 sampling of public drinking water finds PFAS in 97 public drinking water supplies.
2016: Stockholm Convention to add PFOA as a Persistent Organic Pollutant.
February 2016: Guernsey, a Channel Island, loses lawsuit against a manufacturer in pursuit of costs related to cleanup of PFOS-contaminated groundwater and soil.
May 2016: US EPA announces drinking water health advisory limit for PFOS and PFOA (separately or combined) at 70 ppt (ng/L)
© Arcadis 2015
PFAS - Properties and Implications
04 July 2016 15
PFAS plumes are generally longer as PFAS are
generally:
• Highly soluble
• Low KOC
• Recalcitrant – extreme persistence
• Mostly Anionic
Chemical
Properties
PCB
(Arochlor
1260)
PFOA PFOS TCE Benzene
Molecular Weight357.7 414.07 538 131.5 78.11
Solubility (@20-
25°C), mg/L0.0027 3400 – 9500 519 1100 1780
Vapor Pressure
(@25°C), mmHg4.05x10-5 0.5-10 2.48x10-6 77.5 97
Henry’s
Constant, atm-
m3/mol
4.6x10-3 1.01x10-4 3.05x10-9 0.01 0.0056
Log Koc 5 – 7 2.06 2.57 2.473 2.13
© Arcadis 2015
Aqueous Film Forming Foam (AFFF)
• AFFF’s have been used to extinguish class B (liquid hydrocarbon) fires since the 1960’s
• AFFF composition is chemically complex with many organofluorine chemicals which are not detected by commercially available analytical methods (i.e. precursors or polyfluorinated compounds)
• AFFF contains both polyfluorinated and perfluorinated compounds
• The term PFAS (poly- and perfluoroalkylsubstances) is being used to describe all the organofluorine compounds in AFFF
• Polyfluorinated precursor compounds biotransformto make perfluorinated compounds which are extremely persistent
• Perfluorinated compounds in AFFF (i.e. PFOA, PFOS) are extremely Persistent, Bioaccumulativeand Toxic (PBT) so are restricted under Stockholm convention and classed as persistent organic pollutants (POPs)
© Arcadis 2015
Beyond PFOS and PFOA
The diversity of PFAS compounds is much broader than just PFOS and PFOA. Assessing just PFOS / PFOA will miss the bigger picture
• PFOS and PFOA are the most well-known forms of the class of PFAS, but they are not the whole story.
• PFOS and PFOA (C8’s) have generally been replaced with shorter perfluoroalkyl chain forms (C6, C4 etc.) which show diminished bioaccumulation potential
• There are additional perfluoroalkyl carboxylates (PFCAs) and perfluoroalkyl sulphonates (PFSAs), collectively termed PFAA’s (perfluoroalkyl acids) approx. major chain lengths ~C2-C10 (PFCAs) ~C4-C12 (PFSA’s)
• There are many more precursors to PFAA’s in addition to the PFAA’s themselves –polyfluorinated compounds.
• There are thousands of PFAS species that naturally biotransform to make PFAA’s with varying perfluoroalkylchain length (including PFOS and PFOA) - these additional PFAS compounds are rarely measured
© Arcadis 2015
Perfluorinated Compounds
Compounds where every carbon is bonded to fluorine, generally C2 to C16 compounds, but focus has been C8 chemistry i.e. octanoates
In May 2009 PFOS was included in Annex B of the Stockholm Convention on persistent organic pollutants
The European Union practically banned the use of PFOS in finished and semi-finished products in 2006 (maximum content of PFOS: 0.005% which was lowered to 0.001% in 2010).
Use of PFOS for industrial applications (e.g. photolithography, mist suppressants for hard chromium plating, hydraulic fluids for aviation) was exempted
The EU intends to back a global ban on perfluorooctanoic acid (PFOA) and its compounds (25 March 2015)
Perfluorinated sulphonates and carboxylate compounds are collectively termed perfluoroalkyl acids (PFAA’s) and are extremely persistent -totally non-biodegradable
PFOA
PFOS
© Arcadis 2015
Polyfluorinated Compounds
Compounds where every carbon is not bonded to fluorine (contains some C-H bonds)
Fluorotelomers e.g. 6:2 or 8:2 fluorotelomer alcohols
Still manufactured and used in certain AFFF
Break down in the environment to form perfluorinated compounds which persist e.g. 8:2 FTS forms PFOA
Pose potential risk to drinking water resources
Less toxicological data available than for PFOS & PFOA
Will biotransform to make PFAA’s as dead end daughter products
PFOA
© Arcadis 2015
Precursors
Precursors are classed as compounds that have the potential to degrade into long chain perfluoroalkylacids (PFAA’s) generally PFCA’s will form
Precursors are generally polyfluorinated compounds and those that form short chain PFAAs will also exist
There are potentially hundreds of compounds in AFFF formulations which can degrade to form perfluorinated compounds
For examples PFOS precursors include N-methyl perfluorooctane sulfonamidoethanol (N-MeFOSE) and N-ethyl perfluorooctane sulfonamidoethanol (N-EtFOSE)
About 50 precursors were named in the 2004 proposed Canadian ban on PFOS
Precursors biotransform to give PFAA’s as “dead end” persistent daughter products
© Arcadis 2015
Aerobic Biotransformation Funnel
Hundreds of Common
Intermediate
Transformation
Products
Approximately 25 PFSAs,
PFCAs, PFPAs –
collectively termed PFAA’s
All Polyfluorinated / PFAA
Precursor Compounds in
Commerce (“Dark Matter”)
Thousands of PFAA Precursors
Biodegradation of PFAS is
not observed as they
biotransform to produce
PFAA’s as dead end
daughter products that
exhibit extreme persistence
as they do not biodegrade
PFAS compounds do not biodegrade –i.e. mineralize, they biotransform and many parent or intermediate compounds are not detected by conventional analytical methods
© Arcadis 2015
PFAS Manufacturing
• In most of the U.S. and Europe, C8 PFAS species (PFOS and PFOA) have been phased-out due to potential health concerns
• PFOS (C8) and PFOA (C8) and related PFAS have been replaced with compounds with shorter (e.g., C4, C6) perfluorinated chains
• Shorter chain replacement chemicals are typically less bioaccumulative, but they are still extremely persistent and more mobile in aqueous systems vs C8.
• Solutions for characterizing all PFAS species are imperative; multiple carbon chain lengths are present in most environmental samples and even in historical “C8” products
• Regulations addressing multiple chain length PFAS are evolving globally
Non-fluorinated replacement foams are being increasingly adopted
Manufacturer Foam
National Foam Jetfoam (Aviaton)
National Foam Respondol (Class B)
Bioex Ecopol
Fomtec Enviro 3x3 Plus
Solberg Re-healing Foam RF6 / RF3
Dr. Sthamer Moussol F-F3/6
© Arcadis 2015
Perfluorinated carboxylates in consumer products2007-2008
Pre-Treated Carpet
Treated Home Textiles
Food contact paper
Non-stick cookware
• Focus has mainly been on PFOA and PFOS, but PFAS-containing products typically contain a mixture of species in a single product
• C5 to C12 perfluorinated carboxylates are present in many PFOA (C8)-containing consumer products
• Similar diversity of PFAS chain lengths, as well as structures, may be expected in other PFAS-containing products and PFAS-contaminated areas.
Data from Guo et al. 2009, U.S. EPA; Polyfluorinated substances and perfluorinated sulfonates were not measured
© Arcadis 2015
PFAS Exposure, Distribution, and Elimination in Humans
EXPOSURE DISTRIBUTION ELIMINATION
• Most exposure is likely from
ingestion of contaminated food
or water
• Exposure also comes from:
• Breast milk
• Air
• Dust (especially for
children)
• Skin contact with various
consumer products
• Elimination of PFOS and PFOA from the human body takes some years, whereas elimination of shorter chain PFAS are in the range of days
• Apart from chain length, blood half-lives of PFAS are also dependent on gender, PFAS-structure (branched vs. straight isomers), PFAS-type (sulfonates vs. carboxylates) and species.
• Elimination mainly by urine.
• PFAS bind to proteins, not to fats.
• Highest concentrations are found in
blood, liver, kidneys, lung, spleen and
bone marrow.
• PFOS and PFOA have
bioaccumulative properties.
• Shorter chain PFAS generally have a
lower bioaccumulation potential,
although there may be some
exceptions.
© Arcadis 2015
Toxicity
• Several human epidemiological studies show inconsistent results. Elevated levels of PFOS and PFOA are associated with increaes in blood cholsterol and liver damage. It is however not clear, if these effects are caused by PFAS.
• Based on results of chronic studies with animals (mainly mice, rats and monkeys), there are concerns that PFOS and PFOA cause effects on the liver, lipid metabolism, immune response, reproduction and development.
• Extrapolation from animals to humans is difficult, as humans and animals react differently to PFAS.
• The C8 Science Panel determined a probable link between high levels of PFOA exposure and kidney and testicular cancer
• Toxicity of PFAS other than PFOS and PFOA have not been well-characterized.
http://www.c8sciencepanel.org/
© Arcadis 2015
PFAS Exposure Pathways
The PFAS web Oliaei et al. Environ. Sci. Pollut Res (2013) 20: 1977-1992
Multiple exposure pathways for PFAS compounded via bioaccumulation / biomagnification
© Arcadis 2015
Target Regulatory PFAS Values
Drinking Water Criteria in µg/l in European Countries
PFOS PFOA PFOSA PFBS PFBA PFPeA PFHxA PFHpA PFNA PFDA 6:2 FTS PFHpS PFHxS PFPeS
Denmark (0.1) (0.1) (0.1) (0.1) (0.1) (0.1) (0.1) (0.1) (0.1) (0.1) (0.1) - (0.1) -
Germany 0.3 0.3 - - - - - - - - - - - -
The Netherlands 0.53 - - - - - - - - - - - - -
Sweden 0.09 0.09 - 0.09 - - - - - - - - - -
U.K. 0.3 0.3 - - - - - - - - - - - -
Drinking Water Criteria in µg/l U.S.
PFOS PFOA PFOSA PFBS PFBA PFPeA PFHxA PFHpA PFNA PFDA 6:2 FTS PFHpS PFHxS PFPeS
Minnesota 0.3 0.3 - 7 7 - - - - - - - - -
New Jersey - 0.04 - - - - - - 0.013 - - - - -
Vermont 0.02
U.S. EPA 0.07 0.07 - - - - - - - - - - - -
Canada 0.3 0.7 - - - - - - - - - - - -
Groundwater Criteria in µg/l in European Countries
PFOS PFOA PFOSA PFBS PFBA PFPeA PFHxA PFHpA PFNA PFDA 6:2 FTS PFHpS PFHxS PFPeS
Denmark (0.1) (0.1) (0.1) (0.1) (0.1) (0.1) (0.1) (0.1) (0.1) (0.1) (0.1) - (0.1) -
Germany - - - - - - - - - - - - - -
State of Bavaria 0.23 - - 3 7 3 1 0.3 0.3 0.3 - - - -
State of Baden0.23 0.3 - 3 7 3 1 0.3 0.3 0.3 0.3 0.3 0.3 1
Württemberg
The Netherlands 0.023 - - - - - - - - - - - - -
Groundwater Criteria in µg/l in U.S.
PFOS PFOA PFOSA PFBS PFBA PFPeA PFHxA PFHpA PFNA PFDA 6:2 FTS PFHpS PFHxS PFPeS
New Jersey - - - - - - - - 0.02 - - - - -
Texas, Residential 0.56 0.29 0.29 34 71 1.9 1.9 0.56 0.29 0.37 - - 1.9 -
Soil Criteria in mg/kg in European Countries, U.S.
PFOS PFOA PFOSA PFBS PFBA PFPeA PFHxA PFHpA PFNA PFDA 6:2 FTS PFHpS PFHxS PFPeS
Denmark (0.4) (0.4) (0.4) (0.4) (0.4) (0.4) (0.4) (0.4) (0.4) (0.4) (0.4) - (0.4) -
Germany - - - - - - - - - - - - - -
State of BavariaEvaluation for pathway Soil -> Groundwater is based on Leachate Concentrations (µg/l)
Evaluation for recycling of Soils is based on LAGA M20 Criteria
The Netherlands 0.0032 - - - - - - - - - - - - -
Texas, Residential 1.5 0.6 0.058 73 150 5.1 5.1 1.5 0.76 0.96 - - 4.8 -
Values in parentheses refer to PFAS regulated as a sum concentration
Drinking water
Denmark ∑12 PFAS* 100 ng/l
Sweden ∑ 7 PFAS ** 90 ng/l
*∑12 PFAS:
PFBS PFHxS PFOS PFOSA 6:2 FTS PFBA
PFPeA PFHxA PFHpA
PFOA PFNA PFDA
**∑ 7
PFAS:
PFBS PFHxS PFOS PFPeA PFHxA PFHpA
PFOA
© Copyright ARCADIS 2015
PFOS AA-EQS is extremely low / very conservative 0.65 ng/L3 orders of magnitude lower than drinking water standards.
EU Environmental Quality StandardsSurface Waters
• Directive on “Environmental Quality Standards” EQSD 2008/105/EC, daughter directive of the Water Framework Directive: Standards for priority hazardous substances. Review each 6 years. In 2013, PFOS was added as a priority hazardous substance / EQS derived by RIVM (NL).
• Member State Legislation: November 2015. The EQS shall be met by End of 2027.
Name of
substance
Annual Average-EQS
(µg/L)
Max. Allowable Con.
EQS (µg/L)
EQS
(µg/kg)
Inland
surface
waters
Other
surface
waters
Inland
surface
waters
Other
surface
waters
Biota
Perfluoro octane
sulfonic acid and
its derivatives
(PFOS)
0.00065 0.00013 36 7.2 9.1
© Copyright ARCADIS 2015
Analytical Challenges
• AFFF contained many thousands of PFAS compounds including precursors
• Current analytical methods only examine a small fraction of the compounds present (16 - 39 compounds)
• Microbes the attack the non perfluorinated parts of the PFAS precursor molecules making perfluorinatedcompunds as dead end daughter products
• So precursors biotransform to make perfluorinatedcompounds which do not biotransform further and are non-biodegradable
• There are potentially hundreds of PFAS compounds to assess (C2 –C16, straight chain, branched chain, cyclic, telomers, betaines, sulphonamide, amino etc.)
• The analytical costs to assess the concentration of all of these PFAS individually will be substantial
© Arcadis 2015
Advanced Analytical TechniquesExpanding analytical tool box to deal with precursors and cost
New analytical tools applied but not yet proven to be comprehensive..
4 July 2016Useful Graphics 35
LCMSMS
• Most common tool is LCMSMS –Liquid Chromatography with tandem mass spectrometers (US EPA 537)
• Can detects C4 to C12 perfluorinated carboxylates (PFCAs) & sulphonates (PFSAs) (including PFOS & PFOA)
• Detection limits to approx. 0.09 ng/L
Total Oxidisable Precursors (TOP) Assay
• Pre-treatment of samples using conventional chemical oxidation which converts precursors to perfluorinated carboxylates (PFCAs) & sulphonates (PFSAs) which can be detected using by LCMSMS;
• Shows sum of precursors which are converted to PFCA’s & PFSA’s - Done in addition to LCMSMS to provide difference between precursor and free PFCA & PFSA concentrations
• Detection limits similar to LCMSMS to approx. 2 ng/L
Particle Induced Gamma Emmission (PIGE) Spectroscopy• Separation of organofluorine compounds by SPE cartridge then analysis of total fluorine content to give a sum of
fluorinated species (analogous to TPH for hydrocarbons)
• Detection limits to 2.2 ug/L F
Adsorbable Organo Fluorine (AOF)• Separation of organofluorines by synthetic Activated Carbon (AC) & subsequent analysis by hydropyrolysis
combustion ion chromatography (CIC) – sum organofluorine (analogous to TPH for hydrocarbons)
• Detection limits 1 ug/L F
© Arcadis 2015
Digest AFFF precursors and measure the hidden mass: TOP Assay
Analytical tools fail to measure the hidden PFAS precursor mass, the TOP assay solves this
Microbes slowly make simpler PFAA’s (e.g. PFOS / PFOA) from PFAS (PFAA precursors) over 20+ years
Need to determine precursor concentrations
Too many PFAS compounds and precursors –so very expensive analysis
This analytical method convert PFAA precursors to PFAA’s
Termed Total Oxidiseable Precursor (TOP) Assay
© Copyright ARCADIS 2015
0
2,500
5,000
7,500
10,000
Soil Composite Pre-TOP Assay(Average of
Duplicate Data)
Soil CompositePost-TOP Assay
(Average ofDuplicate Data)
Concentr
ation (
µg/k
g)
PFNA (C9)
PFOA (C8)
PFHpA (C7)
PFHxA (C6)
PFPA (C5)
PFBA (C4)
PFOS (C8)
PFHpS (C7)
PFHxS (C6)
PFBS (C4) 0
50
100
150
GroundwaterComposite Pre-TOP
Assay(Average of
Duplicate Data)
GroundwaterComposite Post-TOP
Assay(Average of
Duplicate Data)
Concentr
ation (
µg/l)
PFNA (C9)
PFOA (C8)
PFHpA (C7)
PFHxA (C6)
PFPA (C5)
PFBA (C4)
PFOS (C8)
PFHxS (C6)
PFBS (C4)
Total Oxidisable Precursor (TOP) Assay
• Significant increases in perfluorinated carboxylic acids and sulphonic acids (PFAAs) following TOP assay reveal the hidden mass of PFAA precursors present
– An additional 240% of PFAS in soils and 75% in groundwater
• Demonstrates matrices impacted with AFFF contain a greater mass of PFAS than identified by conventional analysis with LC-MS/MS (EPA Method 537).
Soil Composite Groundwater Composite
240%
increase75%
increase
© Copyright ARCADIS 2015
TOP Assay
• Majority of PFAAs identified following TOP assay comprised C4 to C8 carboxylic and sulphonic acids;
• TOP assay generated 3 order of magnitude increase in soil PFHxA (4.6ug/L to 975ug/L)
0%
10000%
20000%
30000%
PFBS(C4)
PFHxS(C6)
PFHpS(C7)
PFOS(C8)
PFBA(C4)
PFPA(C5)
PFHxA(C6)
PFHpA(C7)
PFOA(C8)
PFNA(C9)
PFDA(C10)
PFUnA(C11)
PFDoA(C12)
6:2 FtS(C8)
% Increase in PFAS Compounds Following TOP Assay in an AFFF-Impacted Soil
© Arcadis 2015
PFAS Measurement in Groundwater with TOP Assay
Only 28% (86 µg/L PFAS) was
measured using standard analytical methods.
Post-TOP assay sample results represent 100% of measurable PFAS
Total PFAS Measured in Pre-TOPAssay Sample
Additional PFAS Measured inPost-TOP Assay Sample
An additional 216 µg/L PFAS was
measured following TOP Assay
© Arcadis 2015
Method Comparison:TOP Assay vs AOF
y = 0.7791x + 1.7479R² = 0.7702
0
10
20
30
40
50
0 10 20 30 40 50
AO
F µ
g/L
(o
rgan
ofl
uo
rin
e)
LC-MS/MS post TOP Sum PFAS (organofluorine equivalent)
© Arcadis 2015
Conceptual Site Model
• Source zone – hidden cationic & cation dominated zwitterion “Dark Matter” in more anaerobic environment
• Mobile zone – hidden anionic & anion dominated zwitterions (more mobile) PFAA precursors, “Dark Matter”
• Anionic precursor biotransformation increases as aerobic conditions develop in the downgradient of hydrocarbon plume
• Increasing mobility of shorter perfluoroalkyl chain PFAS
© Arcadis 2015
P&T with GAC treatment is the most commonly applied technology –less effective on shorter chain PFAS
PFAS Groundwater Remediation• Currently proven commercial option is P&T for C8 compounds
• GAC can be effective in removing PFOS/PFOA, however
sorption is low and competition occurs (much higher costs than
for conventional contaminants)
• GAC increasingly less effective as PFAS chain length
diminishes
• Ion exchange resins or polymers with a large surface area may
be suitable for low concentrations and high volumes,
• Other potential techniques are nano filtration and reverse
osmosis
• Oxidation via conventional methods is difficult due to strength of
the C-F bond and may lead to higher PFCA / PFSA levels as a
result of precursor breakdown using oxidants
• Arcadis ScisoR shown to defluorinate PFOS with in situ treatment
planned for 2016
© Arcadis 2015
PFAS Soil Remediation• Currently options are limited to excavation,
stabilization or capping
• Landfilling introduces challenges since PFAS will
become constituents of leachate (landfill leachate
is not typically being evaluated for e.g. PFOS)
• Incineration, high temperatures (> 1,100 °C) are
needed to cleave the stable C-F-bonds
• Immobilization with GAC or commercial products
(soil mixing) e.g. Rembind.
• Solidification (e.g. cement) is a yet unproven long-
term option
• Arcadis ScisoR trials on soil mixing progressing
Soil remediation largely relies on excavation/stabilization/ immobilization and not destruction
© Copyright ARCADIS 2015
Cost of PFOS Groundwater Treatment with GAC
Low sorption of PFCs → higher GAC consumption, cost
At influent concentrations 3 to 20 µg/L; effluent 0.1 µg/L:
Parameter Charge capacity
(% wt)
Annual GAC Costs ($/Year)
75 Lpm 166 Lpm 832 Lpm 1,665 Lpm
PFOS 0.002 to 0.005 3,932 7,865 39,322 78,643
Chlorinated
hydrocarbons
0.02 to 0.4 256 512 2,555 5,112
BTEX 0.1 to 2.0 52 102 512 1,022
PAH 1.3 to 2.5 29 57 284 568
© Arcadis 2015
0
10000
20000
30000
40000
50000
60000
Blanco SC1-1 SC1-2 SC1-3 SC1-4 SC1-5
H4PFOS
C7A
C7S
C8A
C4S
C5A
C4A
C6A
C6S
C8S
Oxidation Results: peroxide activated persulfateSoil and Groundwater
Conventional ISCO creates PFAA’s from precursors
Co
ncen
tra
tio
n (
ng/L
)
H4PFOSC7A
C7SC8A
C4SC5A
C4AC6A
C6SC8S
0
5000
10000
15000
20000
25000
30000
35000
Blanco SC2-1 SC2-2 SC2-3 SC2-4
H4PFOS
C7A
C7S
C8A
C4S
C5A
C4A
C6A
C6S
C8S
• 300 g soil, 300 mL groundwater
• PFAS monitored in reactor supernatant
© Arcadis 2015
H4PFOSC7A
C7SC8A
C4SC5A
C4AC6A
C6SC8S
0
5000
10000
15000
20000
25000
30000
35000
Blanco SC2-1 SC2-2 SC2-3 SC2-4
H4PFOS
C7A
C7S
C8A
C4S
C5A
C4A
C6A
C6S
C8S
Oxidation Results: ScisoR®
Soil and Groundwater
• Destruction of PFAS and PFAA’s in soil and groundwater by chemical oxidation / reduction using ScisoR®
• Effective at ambient temperature
• Reagents can be injected or mixed with impacted soil and groundwater
• In Situ remediation of PFAS impacted source areas enabled
• Could be used to regenerate sorbent media (e.g. GAC, ion exchange resins)
• Patent granted in NL. Provisional patent in the US. Patent Cooperation Treaty (PCT) procedure pending for worldwide patent rights
Conventional ISCO creates PFAA’s from precursors
ScisoR destroys PFAA’s and precursors
• 300 g soil, 300 mL groundwater
• PFAS monitored in reactor supernatant
© Copyright ARCADIS 2015
0%
20%
40%
60%
80%
100%
120%
Average % PFOSRemaining
Post ScisoR®
PFOS Destruction during ScisoR®
0%
20%
40%
60%
80%
100%
120%
Average % FluorideReleased from
PFOSPost ScisoR®
Fluoride Released from PFOS
during ScisoR®
PFOS Destruction & Fluoride Mass Balance During ScisoR®
• 10 mg/L PFOS starting concentration
• 3 replicate data sets
• 83 to 90% PFOS destruction after 14 days
• 71% to 118% fluoride released from PFOS during SCISOR
• Overall fluoride mass balance (remaining fluoride in PFOS + fluoride released to solution)
− 86% to 126% of theoretical
• All treated samples were blind spiked with 10 mg/L fluoride
− 80% to 99% spike recovery
• Spike analyses demonstrate ion measured is fluoride, results are quantitative
• Longer reaction times and repeat applications of ScisoR will cause complete destruction of PFOS
4 July 2016 51Replicate Data. Error bars are % Standard Error of Measurement (SEM)
© Copyright ARCADIS 2015
Environment Canada -ScisoRPFOA as transformation product of PFOS
water spiked with 100 µg L-1 PFOS
© Copyright ARCADIS 2015
ScisoR Field Demonstrators
• ScisoR Ex Situ On Site Remediation of Unsaturated Soils
• ScisoR In Situ Aquifer Remediation
1. Europe, June 2016 – site work
2. UK, April 2016 – lab
3. North America 2016 – repeat lab with TOP
4. Australia, May 2016 – lab
© Arcadis 2015
PFAS -Manage your risks
• PFAS are highly mobile in groundwater, persistent and toxic
• PFAS sources can comprise fire training areas FTA’s
• Identifying if certain FTA’s are located in environmentally sensitive locations will potentially establish if harm is being caused
• Risk ranking a portfolio of FTA’s is a first logical step to manage potential risk
• Arcadis is working for multiple clients on portfolios of PFAS impacted sites using risk based tools to manage potential risks to multiple receptors from use of PFAS
https://www.epa.gov/ground-water-and-drinking-water/drinking-water-health-advisories-pfoa-and-pfos
US EPA has established the drinking water health advisory
levels at 70 parts per trillion (ng/L) 19th May 2016
© Arcadis 2015
• PFAS do not biodegrade (mineralise) but biotransform to PFAAs as dead-end daughter
products
• Regulations surrounding PFAS are evolving with lowering drinking water standards and a
focus on increased interest in additional PFAAs
• Significant PFAA precursor mass (“Dark Matter”) and multiple PFAAs likely accompany
PFOS & PFOA in sources and plumes –depending on exact nature of source material
• Analysis of just PFAA’s may significantly underrepresent the actual PFAS mass
• Methods to determine the sum PFAS mass are available commercially via ARCADIS and
show good initial correlation
• TOP Assay correlates well with AOF; TOP Assay appears more comprehensive
• A CSM is proposed based on TOP, AOF and PIGE data from an FTA source and plume
• ScisoR has been demonstrated to mineralise PFOS
• Arcadis is moving to field scale application of ScisoR for on site / in situ destruction of
PFAS on 3 continents
Summary
© Arcadis 2015
Contacts
Ian Ross Ph.D.Global PFAS LeadArcadis [email protected]
Jeff BurdickNorth America PFAS LeadArcadis [email protected]
Tessa PancrasEuropean PFAS LeadArcadis [email protected]
Download at:https://www.concawe.eu/publications/558/40/Environmental-fate-and-effects-of-poly-and-perfluoroalkyl-substances-PFAS-report-no-8-16