Ozonation breaks down certain PFAS substances

PFAS are used because of their water and fat-repellent properties in everything from clothes to food packaging and fire fighting foam. But the qualities that have made PFAS popular also make them dangerous, as they are very difficult to break down. PFAS is also stored in the body, and the higher content we get, the greater the risk of various health effects.

- Drinking water is one of the most common sources of PFAS. Purification methods used today are not designed to remove these substances, which means that it will be unnecessarily expensive and ineffective to remove them from the drinking water, says Vera Franke, a PhD student in the research group Organic Environmental Chemistry at SLU. She is working on developing more effective methods to purify our water.

Catalyzed ozone breaks down PFAS

Among other things, Vera Franke's research group has studied the purification method of catalyzed ozonation. This means that by using high concentrations of ozone together with a catalyst, PFAS are broken down into less dangerous substances. The catalyst is used to trigger the decomposition of ozone as ozone alone is unable to break down PFAS.

The researchers have collaborated with a company that uses catalyzed ozonation to break down pharmaceutical residues in wastewater from, for example, the Academic Hospital. Vera Franke and her colleagues used the company's testing facilities to investigate whether catalyzed ozonation also works to break down PFAS.

- We saw that some PFAS substances decreased significantly with this ozonation method, while other substances were not broken down as effectively, says Vera Franke.

May form toxic residues

- If you have problems with certain types of PFAS, catalyzed ozonation is very useful. The forms of PFAS that can be broken down by ozone happen to be the most common in the environment, says Vera Franke.

To date, high concentrations of ozone are not used in the production of drinking water as it can lead to the formation of toxic residues.

- In our studies we did not find any toxic residues as a result of the ozonation. But more tests are needed to ensure the method being safe before ozonation can be approved for drinking water production, says Vera Franke.

Text: Ylva Sjöblom