Fire-fighting foams have contaminated concrete and soils at fire-training and commercial sites across Australia and worldwide. Many so-called aqueous film-forming foams contain per- and poly-fluoroalkyl substances (PFAS) chemicals, which can enter ecosystems and move through food chains, accumulating in animal and human bodies.
‘The modified natural clay, called matCARE™, soaks up toxic substances and binds them irreversibly,’ says Professor Ravi Naidu, Managing Director of the Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE), based in Newcastle, NSW.
Clay has been widely used to absorb and clean up pollution. CRC CARE researchers identified a type of clay that was especially effective at trapping PFAS. They activated the fibrous clay, making it more effective at trapping pollutants. The resulting product irreversibly locks up PFAS, preventing it from leaching into the environment.
‘Concrete acts like a sponge. It has a very porous structure and can readily soak up PFAS. Rain can then wash these pollutants out of the concrete and into soil, creeks, rivers and groundwater,’ says Professor Naidu.
‘A few kilograms of matCARE will successfully treat a typical contaminated site, protecting people and the environment. It is inexpensive and effective.’
CRC CARE scientists Drs Jianhua Du and Danidu Kudagamage have created a nano-powder form of the matCARE clay slurry. The tiny particles penetrate contaminated concrete, locking up the PFAS and preventing it from leaching into the surrounding environment.
There are estimated to be thousands of PFAS-contaminated sites in Australia. ‘Many of the sites include contaminated concrete. Treating these with nano-matCARE will often represent a better, more environmentally friendly and cheaper clean-up method than removing and transporting the concrete for further treatment.’
CRC CARE tests at the University of Newcastle’s Global Centre for Environmental Remediation show that nano-matCARE will immobilise 99.97 per cent of the PFAS chemical perfluorooctanesulfonic acid (PFOS) in contaminated concrete. After 10 months, more than 99.61 per cent of the chemical remains immobilised.
The matCARE slurry also locks up other pollutants in concrete, such as hydrocarbons, and can be used to treat contaminated soil.
CRC CARE does research, develops technologies, and provides policy guidance for assessing, cleaning up and preventing contamination of soil, water and air.
For more information and high-resolution images, please contact: Adam Barclay, CRC CARE Communication Director – 0429 779 228; firstname.lastname@example.org