Post on 18-Jun-2018
COOPERATIVE RESEARCH CENTRE FOR CONTAMINATION ASSESSMENT AND REMEDIATION OF THE ENVIRONMENT
Innovations in PFAS Assessment and Remediation Technologies: An Australian Perspective
Prof Ravi Naidu CEO & Managing Director, CRC CARE 6 March 2018
OUTLINE
• CRC CARE
• Overview of PFAS
• Australia’s national policy
environment
• Toxicological studies
• Remediation challenges
• Innovative technologies
CRC CARE:
• is a partnership of industry, government and research organisations
• is a global centre for research and utilisation of contamination assessment and remediation technologies
• is developing innovative ways to remediate and prevent contamination of soil, water & air
• has key nodes in Australia and China
BACKGROUND-CRC CARE
Cooperative Research Centre for Contamination Assessment and Remediation of the Environment
CRC CARE PARTICIPANTS (29) Site owners/
industry Government Research providers Service providers
PFAS
Ø Most-stable / inert, man-made organic chemicals
Ø Widely used, almost everywhere
PER AND POLY FLUORO ALKYL SUBSTANCES
PFOA
PFOS
FTS
PFAS
Per
Poly
q PFAS properties
PFOS CONTAMINATION
Items PFOA PFOS Implication
Water solubility (20 – 25 °C g/L)
3.4 – 9.5 0.52 – 0.57
Mobility in water, influenced by water chemistry
Vapour pressure (Pa)
4 – 1300 6.7 Minor role
Log Kow (-) 5.3 6.43 Partitioning in organic and aqueous phase, be related to water solubility, soil/sediment adsorption coefficients, bioconcentration factors
Dissociation constant (pKa)
-0.16 – 3.8
-6.0 − -2.6 Negative values indicated strong acid and can dissociate into cations and ions
Normally as anions
PFAS contamination
q PFAS: Per- and poly-fluoroalkyl substances PFAS are widely distributed in the global environment!
Waste site Consumer products
Manufacture sites
Precursor chemicals
Firefighting training
sites
Waste water treatment plants and the environment
Fate and transport
Exposure
Surface water
Groundwater
Soil functionality/biota
Drinking water
Sediments
Human
Issues for Australia • PFAS not manufactured in Australia
• Mostly legacy contamination eg around fire-fighting and storage sites
• Low screening levels, some below levels of detection
• Screening levels are conservative, and should not be used as remediation targets to avoid over-remediation.
• Greater need for site-specific risk assessments
• Expensive (relative to even more expensive remediation)
• Limited by lack of understanding of PFAS fate, behaviour and transport
CRC CARE: PFAS RESEARCH • First recognised by Australia Defence as potential
toxin in 2004; • Defence funds CRC CARE research on PFAS:
2004 – Analytical; – Field assessment; – Policy; – Monitoring tool; – Toxicological; – Sorption; – Waste water & Soil Remediation
Remediation 2015-16: CRC CARE: Comprehensive draft technical guidance for PFOS/PFOA
on site contamination assessment, management and remediation
2016: Health agencies developed further screening levels. Revised subsequently in 2017.
2017: The 9 jurisdictions commenced the development of an overarching PFAS National Environment Management Plan in recognition of the need for an overarching policy document. Scope:
– Guiding principles and obligations concerning PFAS (from sources of PFAS to contaminated wastes) as per Stockholm requirements
– Ambient monitoring for PFAS, inventory of PFAS-containing materials and waste
– Environmental guideline values, PFAS sampling and analysis – Some guidance on risk assessment and remediation – Storage, transport, landfill disposal
Australia’s policy environment
2018: Finalisation of ecological aquatic water guideline values by the Commonwealth Government for:
– Freshwater
– Marine (developed by CRC CARE and under review by the Commonwealth)
: Revision of the PFAS National Environment Management Plan
– Based on further research, and finalisation of all screening levels.
Australia’s policy environment
NewAFFFTestKit• Measuresanionicsurfactant
concentra5on.• Simpletouse• Reliable• Sensi5ve• Safeintermsofhandling• Basedoncolorchartorhand
heldspectrophotometer• Broadapplica5oninthe
detec5onofAFFFthatarebasedonanionicsurfactantsincludingLightWaterandAnsulite
astkCARE™ FIELD TESTING SENSOR KIT
http://www.crccare.com/products-and-services/technologies/astkcare
• Colouration reaction to target PFAS • Colour chart for colour comparison: simple and quick test
astkCARE™ COLOUR READING
OR
Visual reading vs. smartphone app reading
Color justification
astkCARE™ SENSOR: SMARTPHONE APP
• Smartphone app reads colour and converts to concentration
• ppb level test is achievable with sample preparation
• GPS signal is recorded to mark the testing position
Email: ravi.naidu@crccare.com
PFOS CONTAMINATION
The transport of PFAS in soil and aquatic system is an important process in controlling their environmental distribution and fate:
Remediation
source
Leaching
Surface water Run off
Plant uptake Exposed?
Vadose zone
Saturated zone
Biotic transformation Chemical transformation Surface retention
PFOS (perfluorooctane sulfonate) is the most commonly measured PFAS, has been added in the list of Stockholm Convention on POPs in 2009.
CONTAMINATED SITE REMEDIATION: CSM
PFAS BINDING IN SOILS
0 100 200 300 400 500 6000
2
4
6
8
10
BNA STA BDA MTA I TXA GIA SGA BNA STA BDA MTA I TXA GIA SGA
Qe
(µg/
g)
Ce (µg/L)
Model Freundlich (User)Equation Qe=Kf*Ce^(1/n)Plot BNAKf 0.02449 ± 0.07385n 1.58449 ± 1.29191Reduced Chi-Sqr 0.38252R-Square(COD) 0.99999Adj. R-Square 0.99999
Model Freundlich (User)Equation Qe=Kf*Ce^(1/n)Plot STAKf 0.01948 ± 0.05366n 1.36347 ± 0.86841Reduced Chi-Sqr 0.4851R-Square(COD) 0.99999Adj. R-Square 0.99999
Model Freundlich (User)Equation Qe=Kf*Ce^(1/n)Plot BDAKf 0.06897 ± 0.08683n 1.40468 ± 0.438Reduced Chi-Sqr 0.82677R-Square(COD) 0.99998Adj. R-Square 0.99997
Model Freundlich (User)Equation Qe=Kf*Ce^(1/n)Plot IKf 0.13125 ± 0.10071n 1.57766 ± 0.34258Reduced Chi-Sqr 0.50274R-Square(COD) 0.99998Adj. R-Square 0.99998
Model Freundlich (User)Equation Qe=Kf*Ce^(1/n)Plot TXAKf 0.06082 ± 0.084n 1.5876 ± 0.60388Reduced Chi-Sqr 0.43053R-Square(COD) 0.99999Adj. R-Square 0.99999
Model Freundlich (User)Equation Qe=Kf*Ce^(1/n)Plot GIAKf 0.06266 ± 0.09625n 1.58286 ± 0.66863Reduced Chi-Sqr 0.57471R-Square(COD) 0.99999Adj. R-Square 0.99998
Model Freundlich (User)Equation Qe=Kf*Ce^(1/n)Plot SGAKf 0.07914 ± 0.11852n 1.74708 ± 0.7982Reduced Chi-Sqr 0.54368R-Square(COD) 0.99999Adj. R-Square 0.99999
Na-Freundlich
0 50 100 150 200 250 300 350 4000
2
4
6
8
10
12
14
16 BNA STA BDA MTA I TXA GIA SGA BNA STA BDA MTA I TXA GIA SGA
Qe
(µg/
g)
Ce (µg/L)
Model Freundlich (User)Equation Qe=Kf*Ce^(1/n)Plot MTAKf 0.01641 ± 0.00488n 0.63042 ± 0.0284Reduced Chi-Sqr 0.07784R-Square(COD) 0.99994Adj. R-Square 0.99992
Ca-Freundlich
q Freundlich modelling
R2 > 0.999 (using Orthogonal Distance Regression iteration)
ü Values of n ranged 1.133 – 1.747 (NaNO3) and 0.630 – 1.388 (Ca(NO3)2)
ü Kf ranged 0.019 – 1.313 (NaNO3) and 0.005 – 0.143 (Ca(NO3)2)
Ca Na
0.6
0.8
1.0
1.2
1.4
1.6
1.8
Val
ue o
f n
25%~75% Range within 1.5IQR Median Line Mean Outliers
0 1 2 3 4 5 6 7 8
0
5
10
15
20
25
30
35
Na Linear Fit of Sheet1 R"Qm"
Qm
est
imat
ed fr
om L
angm
uir M
odel
TOC
Equation y = a + b*xPlot QmWeight No WeightingIntercept -0.26008 ± 2.36558Slope 3.44551 ± 0.68038Residual Sum of Squares 128.19998Pearson's r 0.90022R-Square(COD) 0.8104Adj. R-Square 0.7788
Qm = 3.45*TOC-0.26; R2 =0.78
Na
1
100
10,000
1,000,000
BNA MTA STA BDA I TXA GIA SGA
Qm
est
imat
ed fr
om
Lang
mui
r mod
el (µ
g/g)
Soil samples
Na Ca
q pH and ionic strength of electrolytes
y = -0.9413x + 13.264 R² = 0.81896
0
2
4
6
8
10
12
3 5 7 9
Qe
(µg/
g)
pH
MTA y = -2.0745x + 18.088 R² = 0.73905
0
2
4
6
8
10
12
3 5 7 9 Q
e (µ
g/g)
pH
I
Ø Adsorption depended on solution pH and decreased with increasing solution pH
Ø The degree of decrease in adsorption varies for different soils
6. Conclusion: Sorption
Ø Different type of soils showed different sorption capacity for PFOS
Ø Kd values from linear isotherm model didn’t show significant correlation with any of the soil properties
Ø Sorption maxim (Qm) calculated from Langmuir model is positively correlated with TOC content of soils
Ø Presence of cations and organic matter influence sorption of PFOS
Ø Sorption of PFOS on soils decreased with pH indicating electrostatic interaction
TOXICOLOGICAL STUDIES
• Toxicity of perfluorooctanoic acid towards earthworm and enzymatic activities in soil�
• Perfluorooctane sulfonate release pattern from soils of fire training areas in Australia and its bioaccumulation potential in the earthworm Eisenia fetida
No mortality in earthworms exposed up to 100 mg PFOA/kg soil- there was however significant weight loss from 25 mg/kg upwards
Significant bioaccumulation (BA) of PFOS by earthworms corresponding to weight loss with BA decreasing with increasing clay and OM content
Toxicitytosoilbiologicalac.vity-EdinburghRAAFBase
y = -9.7034Ln(x) + 77.212R2 = 0.6416
0
5
10
15
20
25
30
35
40
45
0 500 1000 1500 2000
PFOS (mg/kg soil)
Ure
ase
Activ
ity (u
g/g/
h)
y = -161.9Ln(x) + 1463.8R2 = 0.3201
0
200
400
600
800
1000
1200
0 500 1000 1500 2000
PFOS (mg/kg soil)
mic
robi
al b
iom
ass
C (
mg/
kg)
y = -89.114Ln(x) + 765.66R2 = 0.454
0
100
200
300
400
500
600
0 500 1000 1500 2000
PFOS (mg/kg)
Nitr
ifica
tion
(ug/
g/h)
Bio-concentra.onofPFOSintoearthworm-WilliamtownRAAFBase
y = -27.35Ln(x) + 88.997R2 = 0.628
0102030405060708090
100
0 2 4 6 8 10
PFOS (mg/kg)
earth
wor
m b
ioco
ncon
cent
ratio
n Fa
ctor
TOXICOLOGICAL STUDIES
• Cyto- and genetoxic effects of Class B firefighting foam products- mainly used for controlling hydrocarbon fuel fires- fluorinated concentrates: Tridol-3% and Tridol-S 6%. Root meristem cells of A. cepa were used for chromosomal aberration (cytotoxicity) and comet assay (genotoxicity)- root tips were exposed to 6 different concentrations (0% to 0.05%) for 24 h- these concentrations are much lower than used for fire suppression
Incidence of chromosomal aberrations and micronuclei in A. cepa root meristem cells was significant even at lower test concentrations (0.005%).
TOXICOLOGICAL STUDIES
• Investigate the chronic toxicity in soil organism (Eisenia fetida) at molecular level and identify molecular markers to detect PFOS in soil by – Carrying out mRNA sequencing of control and chronically PFOS exposed
E. fetida – Reconstructing the transcripts in silico and identified the differentially
expressed genes
Chronic PFOS exposure alters the expresson of neuronal development-related human homologues in Eisenia fetida
REMEDIATION CONSIDERATIONS
PFAS in environment
Removal from water and soil systems by chemical and physical methods
Broken down to low/non toxic chemicals: v Degradation by biological
methods v Decompose by chemical
methods
Con
cent
ratio
n
Recycle/Disposal
?
?
? Imm
obilisation to reduce risks
Water remediation Response (depending on risk assessment)
Technology
No action None Institutional controls Access / use restrictions
Containment Physical barriers Pumping controls
Removal Pumping (on-site treatment and disposal to sewer/off-site treatment and disposal to sewer)
In-situ treatment Biological / physical (natural attenuation, phytoremediation) Physical-chemical (chemical oxidation)
Ex-situ treatment Chemical oxidation Filtration and sorption (GAC, PAC, matCARE, rembind) Ion exchange resins
Pros and cons for each!!! For more information, refer to CRC CARE guidance
Water remediation
Chemical Immobilization
Chemical speciation
Toxicity and mobility
Solution and solid phase reactions
Chemical immobilization exploits these reactions to alter and control the solubility and speciation of contaminant
In situ soil amendment
Wastewater pumped into the reactors
Clean water holding tank prior to aquifer injection
Clean water Wastewater
matCARETM: setup (i)
Wastewater remediation (AFFF) – 3ML remediated
WASTE WATER REMEDIATION PLANT
Purification Contact Chamber
10 Ft container
2x FSI Poly pre-filters
Feed from pump Bredel Hose SPX15 To External
10,000L Discharge Tank Poly lined
Steel bund- 100mm high
3x Matcare Filters
matCARETM: setup (ii)
• Future Practice- Mobile AFFF treatment plant mounted on a trailer
• Plant size modular to required treatment volume • No civil works required for placing the plant / equipment's • Mobile and mounted on wheels and does not necessitate heavy lifting • Plumbing is flexible to required discharge lengths • Dual power supply with genset in built in case power supply is unavailable • Preventive Maintenance is easy at parked locations • Can be transported to required site
http://www.crccare.com/products-and-services/technologies/matcare
Mineralisation of C-F bond Extremely stable of F-C bonds
More difficult to be broken down
Ø Breakdown is just a beginning towards full mineralisation.
CF3-CF2-CF2-CF2-CF2-CF2-CF2-COOH
HF + CO2
Direct electro-oxidation >2.89 V
Ø General oxidants works slowly, days to months à need catalysis.
Ø Only strong oxidants can offer quick response. à such as direct electro-oxidation of pfasCARETM.
Capacity to mineralise ---C-F bond More powerful to
break down
2
1
C. Fang…, Naidu Environmental Toxicology and Chemistry, 2015, 34(11), 2625–2628 C. Fang…,Naidu Austin Environmental Sciences, 2016, 1(1), 1005 (invited)
Advanced Oxidation Process (AOP)
…Richard J. Watts, Environ. Sci. Technol. Lett., 2014, 1 (1), pp 117–121
Ø No or less chemical used. Ø Water treatment processes of the 21st century. Ø Radical is among the most aggressive / powerful oxidants. Ø Radical alone is NOT enough for PFAS breakdown
à Need more powerful items.
Basically, radical of ●OH 1. UV based
H2O2 + UV → 2 ●OH 2. Ozone based
O3 + HO2− → HO2● + O3−· 3. Sono, electricity…
Energy + H2O à ●OH
Electrochemical Advanced Oxidation Process (EAOP)
…Xiaomin Sun, Environ. Sci. Technol., 2013, 47 (24), pp 14341–14349
Ø Electricity to degrade PFASs directly and to generate radicals as well. à More powerful than radicals/AOP.
Ø Key: electrode material to convert electricity to power decomposition of C—F bond.
Electrode materials
http://www.diamond-materials.com/EN/products/disks_films_membranes/disks.htm
Diamond electrode
$ 10-30 / bigger size > $1000 / wafer
pfasCARETM
pfasCARETM: Setup
1. C. Fang, …Naidu, Trends in Analytical Chemistry, 2017,86, 143–154. 2. C. Fang, …Naidu , Electroanalysis, 2017, 29, 1095–1102. 3. C. Fang, …Naidu, J. Electroanal. Chem. 2017, 785, 249-254. 4. C. Fang, …Naidu, Electroanalysis. 2017, DOI: 10.1002/elan.201700108.
Ø pfasCARETM uses much cheaper materials. Ø Ongoing research towards scale-up of the technology.
pfasCARETM: Results
Before After
4 hours vs. 10 hours, 40 ppm vs. 5 ppm
Ø >99% breakdown. Ø Improvement ongoing.
0 2 4 6 8 10
0
2
4
6
c / p
pm
t / h0 2 4
0
10
20
30
[PFOA] /
ppm
t / h
Ø Cost of diamond à Cheap pfasCARETM
Ø Efficiency improvement à Catalysis Ø Preferred at high concentration à No overshooting
C. Fang, R. Naidu and M. Mallavarapu (2016). Australia. Patent Application 2016903457/AN2016903806 C. Fang, M. Mallavarapu and R. Naidu, JAOT, 2017, DOI: https://doi.org/10.1515/jaots-2017-0014 (in press)
pfasCARETM: remark (i)
PFA
S
C1 (CO2)
Electricity driving Mineralisation Breakdown / degradation
C8 C7 C6 C5 C4 C3 C3 C2
HF + CO2
HF + CO2
Ø Universal: to degrade almost all organic contaminants, including PFASs, TPH, PAH, TCE, pesticides that can’t go through common approaches;
Ø Clean: environmental-friendly, using electricity rather than chemical / biological reagents;
Ø Effective: < 1day (hours), ~100% mineralisation;
Ø Easy: electrochemical operation, robustness, remotely controllable, solar-driving etc.
Ø Drawbacks – Energy consumption. à PFASs – Aftermath treatment. à F-
pfasCARETM: remark (ii)
Response (depending on risk assessment)
Technology
No action None Institutional controls Access / use restrictions Containment Capping
Physical barriers Removal Excavation (to the extent practicable) – off-
site, or on-site and treatment/re-use, or on-site capsulation Biological (natural attenuation, phytoremediation)
In-situ treatment Physical-chemical treatment (solidification/stabilisation eg matCARE, rembind)
Ex-situ treatment Physical-chemical treatment (soil washing, solidification / stabilisation eg matCARE, rembind) Direct thermal desorption Chemical oxidation Incineration
Pros and cons for each!!! For more information, refer to CRC CARE guidance
Soil remediation
Risk-based approach in remediation decisions: contaminated soils
The aims of remediation are to: • reduce the actual or potential environmental
threat and • reduce unacceptable risks to man, animals and
the environment to acceptable levels (Wood, 1997)
Contaminants only pose a risk if they are, or become, available in a form that can impact on human or ecosystem health.
Pathway(s)
Receptor(s)
Source
RISK REDUCTION “Could be low cost, in situ management and hence most attractive remediation technique- Key to risk reduction: development of techniques that enable significant bioavailability reduction and this must be reliable and sustainable over long-term”
Regulator requirement: outcome fulfils NEPM using OECD and other regulatory tests
• The contaminant will not be removed, but the leachability is reduced by immobilizing the contaminant(s).
• Minimise exposure via minimisation of the fraction of contaminant that poses risk.
• In place management of contaminated soil via immobilisation of contaminants that minimises bioavailable fraction and potential risk to receptors.
Immobilization, In situ
Risk based approach.
matCARETM: Groundwater & Soil
http://www.crccare.com/products-and-services/technologies/matcare
Ø Immobilise / lock PFASs to restore soil to valuable real estate. Ø Mineral matrix is much more stable than resin and other man-made
ones to decrease the leakage possibility for long term.
Future Research Directions ü Characterisation of PFAS in trade waste water/sewer systems; ü Ambient concentrations of PFAS across Australia in different mediums
where PFAS contamination may occur; ü Toxicity equivalence for short an long chain – PFSA and PFCA to allow
for risk assessment of broader suite of PFAS; ü Bioaccumulation of PFAS in Australian context including wild life; ü Ecological guideline values ü Importance of sediment PFAS concentration to ecotoxicity and
bioaccumulation ü Fate and behaviour of PFAS: includes sorption and transport in soil and
sediment including environmental factors; ü Fate, behaviour and transport of precursors and kinetics of their
degradation to form PFAS; ü Mineralisation of PFAS to benign products; ü Field monitoring tools- development and validation
Acknowledgements
Thank you for your attention!