Sending PFAS packing, permanently

In response to growing demand for an effective way to permanently remove PFAS from the environment, AECOM has collaborated with the University of Georgia to devise a reliable, permanent and cost-effective solution.

Per- and poly-fluoroalkyl substances (PFAS) are man-made chemicals that were used for industrial purposes since the 1950s. The unique properties of PFAS resist heat, oil, stains and water, and in the past have been exploited for many commercial and industrial applications — notably in historical formulations of aqueous film forming foam (AFFF), which is used to rapidly extinguish fuel-related fires.

The presence of PFAS in the environment is concerning because these chemicals do not break down easily by any natural process, meaning that they are present at low levels everywhere in the environment. Due to their persistent nature, PFAS are under a high degree of environmental regulatory scrutiny, which is expected to continue — and possibly intensify — over the next decade.

“The same properties that make PFAS so effective in industrial processes and firefighting also make them extremely difficult to eliminate from the environment or waste material,” said Dr Rachael Casson, AECOM International PFAS Program Director. “To date, PFAS in contaminated groundwater or liquids was either stockpiled or incinerated at a huge cost.

“Working with the University of Georgia, we have developed a solution that can be set up onsite and eliminates PFAS-concentrated liquids in a sustainable and cost-effective way. We are now able to help our clients to meet the stringent regulatory requirements that govern PFAS contamination.”

Trials of DE-FLUORO

Over the last 12 months, in collaboration with the University of Georgia, AECOM has been trialling the DE-FLUORO electrochemical oxidation system’s capacity to destroy a diverse range of PFAS samples that were provided by organisations from sectors including aviation, defence, manufacturing and petrochemicals.

During trials, DE-FLUORO removed PFAS from groundwater taken from two fire-training sites, PFAS-impacted surface water, as well as from PFAS-remediated waste solution and AFFF concentrate.

“We have been searching for a way to dispose of this contaminant in a safe and cost-effective way for some time,” said Gavin Scherer, AECOM Australia and New Zealand’s PFAS response leader.

“We’d like to thank all of the clients that participated in the trials and enabled AECOM to test the efficacy of the technology. Now we are ready to help them clean up a legacy of PFAS that has built up over decades.”

PFAS samples

The samples provided for the PFAS-destruction trials contained a broad range of PFAS concentrations, from extremely low (parts per billion [ppb]) to extremely high (parts per million [ppm]). The sum of PFAS concentrations in client-supplied samples ranged from 27.3 to 6,380,000 ppb (equal to 6380 ppm).

Concentrations of ‘regulated PFAS’ (perfluorooctane sulfonic acid [PFOS], perfluorooctanoic acid [PFOA] and perfluorohexane sulfonic acid [PFHxS]) in the samples ranged from 13.4 to 5,837,000 ppb (5837 ppm).

The above data shows that DE-FLUORO destroyed between 90 and 100% of the total PFAS mass in the majority of samples treated, as well as between 98 and 100% of regulated PFAS mass, in all but two samples. For a larger image, click here.

“We are confident that if we had extended the duration of the trials it would have resulted in DE-FLOURO completely removing 100% of PFAS from all samples tested,” Scherer said.

The AFFF concentrate product was subject to the least PFAS percentage mass reduction by DE-FLUORO; however, the greatest reductions in PFAS concentrations were observed for this sample. AECOM noted that this is related to the extremely high pre-treatment concentrations of PFAS (6,380,000 ppb) and the limited retention times for the trial.

DE-FLUORO facts:

• DE-FLUORO treats measurable and unmeasurable PFAS compounds with a range of compound signatures.
• DE-FLUORO is not limited by PFAS concentration, nor by the presence of other contaminants.
• Further tests are underway to confirm that extending the treatment duration would enable DE-FLUORO to completely eliminate PFAS.

 Image credit: ©stock.adobe.com/au/Kzenon