Researchers find Australian native plants remove toxic chemicals from polluted waterways


Toxic chemicals known as “PFAS” have been used since the 1950s to make products that resist heat, stains, grease and water – and even put out fires. 

Over time, these chemicals have worked their way into water and soil, migrating through contaminated sites to accumulate in the bodies of animals and people, causing harmful health effects on the immune systems of those who come into contact with it – including cancer and infertility. 

But new research from the University of South Australia may have found the answer to safely removing toxic perfluoroalkyl and polyfluoroalkyl substances, or PFAS, from the environment. 

The researchers found that Australian native reeds were highly effective at cleaning contaminated water of the harmful chemicals.

The Australian rushes used – phragmites australis, baumea articulata, and juncus kraussii – were effective at removing PFAS contaminants from surface water by a whopping 42 – 53 per cent. 

UniSA and CSIRO researcher Dr John Awad said this research could be the answer to providing a clean, green, and affordable method to remove PFAS from the environment.

wetlands researcher in grass
Dr John Awad is an environmental researcher at the University of South Australia.

“PFASs are often referred to as ‘forever chemicals’ because they don’t break down, instead accumulating in the environment and in our bodies where they can cause adverse health effects,” Dr Awad said.

“In Australia, PFAS concerns often relate to the use of firefighting foam – especially legacy firefighting foam – which accumulates in the surface water of our waterways.

“Our research tested the effectiveness of Australian rushes to remove PFAS chemicals from stormwater, finding that phragmites australis was the most effective at absorbing chemicals through its roots and shoots.”

To test the hypothesis, the researchers constructed floating wetlands as a mechanism for plants to grow hydroponically. Dr Awad said that this technique would be the most effective way for the plants to be installed into polluted waterways. 

“Constructed floating wetlands can be readily installed into existing urban environments, such as holding reservoirs and retention basins, making them highly manoeuvrable and adaptable to local waterways,” Dr Awad said.

“Plus, as this innovative water treatment system does not require pumping or the ongoing addition of chemicals, it is a cost-effective remediation system for PFAS removal.”

Using these plants in this way has been done before, he said, for nutrient removal and for heavy metal removal – but never for PFAS removal.

“Add native plants to the mix and we have delivered a truly clean, green and environmentally-friendly method for removing toxic PFAS chemicals from contaminated water.”

The research was done under controlled laboratory conditions, so the next steps are to replicate the study under natural conditions.

“We’re really looking forward to putting this system into the real world,” he said. 

Once harvested, the researchers are looking for a circular economy solution – to create biochar from the plants, which can be used in agriculture. 

“So, instead of the plant becoming waste, we can reuse it.”