When water is contaminated with PFAS, there currently a couple of options used for the safe removal of PFAS, though both have some significant drawbacks. One effective approach is to use reverse osmosis (RO), convert the concentrate to a solid and then incinerate the concentrated solid remains. However, RO is extremely expensive and the process removes all compounds from the water, not just the PFAS. This means that the waste generated includes lots of material that isn’t actually harmful, so there’s inefficiency. RO also requires a huge amount of energy. And once it’s done, all of the concentrated waste needs to be incinerated. This can be problematic, as temperatures must reach 1100-1200°C to properly destroy the PFAS and many industry-grade incinerators currently in operation top out at around 800°C.
Another approach is carbon filtration. Contaminated water is passed through a carbon filter, and the PFAS will be absorbed by (and adsorbed to) the filter. This method works for long-chain PFAS, but is less effective for short-chain PFAS (remember, there are 4000+ kinds). Much like RO, carbon filtration isn’t selective, so all compounds will be removed. Then there is the issue of when to change the filter, and how to dispose of the filter (probably incineration, again difficult to do at the proper temperature).
As PFAS continues to draw the attention of governments and regulators as a contaminant of concern, the remediation industry will push to explore innovative approaches for water and soil treatment. In the meantime, hold onto your raincoat and avoid spraying Scotch Guard near a storm drain.