Remediation Technologies for PFAS Contaminated Soil Richard Stewart, - - PowerPoint PPT Presentation

Remediation Technologies for PFAS Contaminated Soil

Richard Stewart, Ziltek Pty Ltd

Environmental Management of Firefighting Foam Policy Implementation Seminar 21‐23 February 2017 PFAS = Per‐ and Polyfluorinated Alkyl Substances

PFAS contaminated soil

?

• Construction
• Site remediation
• Spill clean up
• Source removal

PFAS contaminated soil

Landfill disposal

October 2016

Landfill disposal

October 2016

~$150 to $550 per tonne

Soil treatment technologies

Technology Feasible for PFAS in soil? Commercially used in Australia to treat PFAS in soil? Biodegradation No No Chemical oxidation/reduction Maybe No Thermal desorption Maybe Indirect Incineration Yes Limited Soil washing Yes No Onsite encapsulation Yes No Solidification Maybe No Emerging technologies (e.g. sonication, electrochemistry, in situ sequestration) Maybe No Immobilisation Yes Yes

What is immobilisation?

• Adding a reagent to bind up the

contaminants – also called ‘chemical fixation’, ‘stabilisation’

• Reduces leaching and risk to human

health and the environment

• Proprietary reagents for PFAS

include RemBind™ and MatCare™

• Powdered activated carbon has also

been tested

PFOS

What is immobilisation?

• Adding a reagent to bind up the

contaminants – also called ‘chemical fixation’, ‘stabilisation’

• Reduces leaching and risk to human

health and the environment

• Proprietary reagents for PFAS

include RemBind™ and MatCare™

• Powdered activated carbon has also

been tested in trials

PFOS ~$40 to $150 per tonne

Why use immobilisation?

Ex‐situ treatment In‐situ treatment

Leave in place Onsite reuse

Landfill ‐ reduced hazard

RemBind – an Australian example of PFAS immobilisation in soil

• A powdered reagent that binds to PFAS in soil to

prevent leaching

• Has passed extensive independent testing by

government airport authorities

• Has been used commercially to treat PFAS

contaminated soil in Australia and the USA

How does it work?

+ + + + ‐ ‐ ‐ ‐ Van der Waals Activated Carbon Electrostatic Interactions Aluminium Hydroxide (Amorphous)

+++++++

Physical Binding

Point of zero charge > pH 9.1

Hydrophobic Interactions

• Add RemBind to soil at ~1% to 5% by weight
• Adjust to ~30% moisture
• Wait 24 hrs for the binding reaction to occur
• Key success factor = optimal surface area contact

How is it applied?

Treating 15,000 m3 of contaminated soil using RemBind, Sydney, Australia

In‐situ application

How effective is RemBind at binding PFAS?

How effective is RemBind at binding PFAS?

How effective is RemBind at binding PFAS?

How effective is RemBind at binding PFAS?

How stable is the binding reaction?

• Because RemBind doesn’t destroy the contaminants, it is

critical to prove the long term stability of the binding

• Multiple Extraction Procedure (USEPA 1320) simulates 1,000

yrs of acid rain conditions in an improperly designed landfill

Site 1 ‐ RemBind Plus Treatment Leach EP 1 2 3 4 5 6 7 8 9 PFOS ug/L 0.04 0.02 <0.02 <0.02 0.02 <0.02 <0.02 <0.02 <0.02 <0.02 pH 3 5 5 5 5 5 5 5 5 5

How effective is RemBind at binding PFAS?

96% reduction PFOS 90% reduction PFOS 99% reduction PFOS 98% reduction PFOS

Commercial application of RemBind for treatment of PFAS in soil in Australia

• In December 2015, RemBind was used to

remediate 1,000 tonnes of PFAS soil from two airport sites in Australia

• Used a purpose‐built burial cell with a pure

RemBind liner and cap

• Regulatory approval for landfill disposal was

granted with no ongoing remediation requirements

Regulatory target = 0.2 µg/L

January 2017, Cape Cod, Massachusetts, USA

Summary

• Current options for PFAS soil treatment in Australia:
• Landfill disposal
• Immobilisation
• Incineration and thermal desorption?
• Other technologies under development, this space

is moving quickly!

• The regulatory environment is still unclear.