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!