Innovations in PFAS Assessment and Remediation Technologies: An Australian Perspective

Transcription

1 Innovations in PFAS Assessment and Remediation Technologies: An Australian Perspective Prof Ravi Naidu CEO & Managing Director, CRC CARE 6 March 2018 COOPERATIVE RESEARCH CENTRE FOR CONTAMINATION ASSESSMENT AND REMEDIATION OF THE ENVIRONMENT

2 OUTLINE CRC CARE Overview of PFAS Australia s national policy environment Toxicological studies Remediation challenges Innovative technologies

3 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 Cooperative Research Centre for Contamination Assessment and Remediation of the Environment BACKGROUND-CRC CARE

4 CRC CARE PARTICIPANTS (29) Site owners/ industry Government Research providers Service providers

5 PFAS PER AND POLY FLUORO ALKYL SUBSTANCES PFOS PFAS Per PFOA Ø Most-stable / inert, manmade organic chemicals Ø Widely used, almost everywhere Poly FTS

6 q PFAS properties Items PFOA PFOS Implication Water solubility (20 25 C g/l) Vapour pressure (Pa) Minor role Mobility in water, influenced by water chemistry Log Kow (-) Partitioning in organic and aqueous anions phase, be related to water solubility, soil/sediment adsorption coefficients, bioconcentration factors Dissociation constant (pka) Normally as Negative values indicated strong acid and can dissociate into cations and ions PFOS CONTAMINATION

7 PFAS contamination q PFAS: Per- and poly-fluoroalkyl substances Waste site PFAS are widely distributed in the global environment! Consumer products Manufacture sites Precursor chemicals Firefighting training sites Waste water treatment plants and the environment Surface water Groundwater Fate and transport Exposure Sediments Drinking water Soil functionality/biota Human

8 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

9 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

10 Remediation Australia s policy environment : 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 : 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

11 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.

12 New AFFF Test Kit Measures anionic surfactant concentra5on. Simple to use Reliable Sensi5ve Safe in terms of handling Based on color chart or hand held spectrophotometer Broad applica5on in the detec5on of AFFF that are based on anionic surfactants including Light Water and Ansulite

13 astkcare FIELD TESTING SENSOR KIT Colouration reaction to target PFAS Colour chart for colour comparison: simple and quick test

14 astkcare COLOUR READING Color justification OR Visual reading vs. smartphone app reading

15 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

16 CONTAMINATED SITE REMEDIATION: CSM The transport of PFAS in soil and aquatic system is an important process in controlling their environmental distribution and fate: Remediation Plant uptake Exposed? source Run off Surface water Vadose zone Biotic transformation Chemical transformation Surface retention Leaching PFOS (perfluorooctane sulfonate) is the most commonly measured PFAS, has been added in the list of Stockholm PFOS CONTAMINATION Convention on POPs in Saturated zone

17 PFAS BINDING IN SOILS

18 q Freundlich modelling Qe (µg/g) R 2 > (using Orthogonal Distance Regression iteration) Na-Freundlich BNA STA BDA MTA I TXA GIA SGA BNA STA BDA MTA I TXA GIA SGA Ce (µg/l) Qe (µg/g) Ca-Freundlich BNA STA BDA MTA I TXA GIA SGA BNA STA BDA MTA I TXA GIA SGA Ce (µg/l) 1.8 Model Freundlich (User) Equation Qe=Kf*Ce^(1/n) Plot MTA Kf ± n ± Reduced Chi-Sqr R-Square(COD) Adj. R-Square ü Values of n ranged (NaNO 3 ) and (Ca(NO 3 ) 2 ) ü Kf ranged (NaNO 3 ) and (Ca(NO 3 ) 2 ) Value of n %~75% Range within 1.5IQR Median Line Mean Outliers Ca Na

19 Qm estimated from Langmuir model (µg/g) 1,000,000 10, Na Ca BNA MTA STA BDA I Soil samples TXA GIA SGA Q m estimated from Langmuir Model Na Q m = 3.45*TOC-0.26; R 2 = TOC

20 q ph and ionic strength of electrolytes Qe (µg/g) MTA I 10 y = x R² = y = x R² = Qe (µg/g) ph ph Ø Adsorption depended on solution ph and decreased with increasing solution ph Ø The degree of decrease in adsorption varies for different soils

21 6. Conclusion: Sorption Ø Different type of soils showed different sorption capacity for PFOS Ø K d 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

22 TOXICOLOGICAL STUDIES Toxicity of perfluorooctanoic acid towards earthworm and enzymatic activities in soil No mortality in earthworms exposed up to 100 mg PFOA/kg soilthere was however significant weight loss from 25 mg/kg upwards Perfluorooctane sulfonate release pattern from soils of fire training areas in Australia and its bioaccumulation potential in the earthworm Eisenia fetida Significant bioaccumulation (BA) of PFOS by earthworms corresponding to weight loss with BA decreasing with increasing clay and OM content

23 45 Toxicity to soil biological ac.vity-edinburgh RAAF Base Urease Activity (ug/g/h) microbial biomass C (mg/kg) y = Ln(x) R 2 = PFOS (mg/kg soil) y = Ln(x) R 2 = PFOS (mg/kg soil) Nitrification (ug/g/h) y = Ln(x) R 2 = PFOS (mg/kg)

24 Bio-concentra.on of PFOS into earthworm-williamtown RAAF Base earthworm bioconconcentration Factor y = Ln(x) R 2 = PFOS (mg/kg)

25 TOXICOLOGICAL STUDIES Cyto- and genetoxic effects of Class B firefighting foam productsmainly 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%).

26 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 developmentrelated human homologues in Eisenia fetida

27 REMEDIATION CONSIDERATIONS Immobilisation to reduce risks? PFAS in environment?? Broken down to low/non toxic chemicals: v Degradation by biological methods v Decompose by chemical methods Removal from water and soil systems by chemical and physical methods Concentration Recycle/Disposal

28 Water remediation Water remediation Response (depending on risk assessment) No action Institutional controls Containment Removal In-situ treatment Ex-situ treatment Technology None Access / use restrictions Physical barriers Pumping controls Pumping (on-site treatment and disposal to sewer/off-site treatment and disposal to sewer) Biological / physical (natural attenuation, phytoremediation) Physical-chemical (chemical oxidation) 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

29 Chemical Immobilization Solution and solid phase reactions Chemical speciation Toxicity and mobility Chemical immobilization exploits these reactions to alter and control the solubility and speciation of contaminant In situ soil amendment

30 matcare TM : setup (i) Wastewater pumped into the reactors Clean water holding tank prior to aquifer injection Wastewater Clean water Wastewater remediation (AFFF) 3ML remediated

31 WASTE WATER REMEDIATION PLANT 10 Ft container 2x FSI Poly prefilters Purification Contact Chamber 3x Matcare Filters Feed from pump Bredel Hose SPX15 To External 10,000L Discharge Tank Poly lined Steel bund- 100mm high

32 matcare TM : 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

33 Mineralisation of C-F bond Extremely stable of F-C bonds More difficult to be broken down CF 3 -CF 2 -CF 2 -CF 2 -CF 2 -CF 2 -CF 2 -COOH HF + CO 2 Ø Breakdown is just a beginning towards full mineralisation.

34 Capacity to mineralise ---C-F bond More powerful to break down 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 pfascare TM. C. Fang, Naidu Environmental Toxicology and Chemistry, 2015, 34(11), C. Fang,Naidu Austin Environmental Sciences, 2016, 1(1), 1005 (invited)

35 Advanced Oxidation Process (AOP) Basically, radical of OH 1. UV based H 2 O 2 + UV 2 OH 2. Ozone based O 3 + HO 2 HO 2 + O 3 3. Sono, electricity Energy + H 2 O à OH 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. Richard J. Watts, Environ. Sci. Technol. Lett., 2014, 1 (1), pp

36 Electrochemical Advanced Oxidation Process (EAOP) 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. Xiaomin Sun, Environ. Sci. Technol., 2013, 47 (24), pp

37 Electrode materials Diamond electrode pfascare TM disks_films_membranes/ disks.htm > $1000 / wafer $ / bigger size

38 pfascare TM : Setup Ø pfascare TM uses much cheaper materials. Ø Ongoing research towards scale-up of the technology. 1. C. Fang, Naidu, Trends in Analytical Chemistry, 2017,86, C. Fang, Naidu, Electroanalysis, 2017, 29, C. Fang, Naidu, J. Electroanal. Chem. 2017, 785, C. Fang, Naidu, Electroanalysis. 2017, DOI: /elan

39 pfascare TM : Results Before After [PFOA] / ppm hours vs. 10 hours, 40 ppm vs. 5 ppm c / ppm t / h Ø >99% breakdown. Ø Improvement ongoing t / h

40 pfascare TM : remark (i) Electricity driving Breakdown / degradation Mineralisation HF + CO 2 PFAS C8 C7 C6 C5 C4 C3 C3 C2 C1 (CO 2 ) HF + CO 2 Ø Cost of diamond à Cheap pfascare TM Ø Efficiency improvement à Catalysis Ø Preferred at high concentration à No overshooting C. Fang, R. Naidu and M. Mallavarapu (2016). Australia. Patent Application /AN C. Fang, M. Mallavarapu and R. Naidu, JAOT, 2017, DOI: (in press)

41 pfascare TM : remark (ii) 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 -

42 Response (depending on risk assessment) No action Institutional controls Containment Removal In-situ treatment Soil remediation Technology None Access / use restrictions Capping Physical barriers Excavation (to the extent practicable) offsite, or on-site and treatment/re-use, or on-site capsulation Biological (natural attenuation, phytoremediation) Physical-chemical treatment (solidification/ stabilisation eg matcare, rembind) Pros and cons for each!!! For more information, refer to CRC CARE guidance Ex-situ treatment Physical-chemical treatment (soil washing, solidification / stabilisation eg matcare, rembind) Direct thermal desorption Chemical oxidation Incineration

43 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. Source Pathway(s) Receptor(s)

44 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 longterm Regulator requirement: outcome fulfils NEPM using OECD and other regulatory tests

45 Immobilization, In situ 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. Risk based approach.

46 matcare TM : Groundwater & Soil 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.

47 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

48 Acknowledgements Thank you for your attention!