A technology initially developed in Australia by OPEC Systems (Emu Plains, NSW, Australia; www.opecsystems.com) for separating and concentrating per- and polyfluoroalkyl substances (PFAS) in a range of water applications has now been introduced in North America.
The technology, known as surface active foam fractionation (SAFF), is an environmentally sustainable separation method that is capable of removing >99.8% of regulated PFAS compounds from water, according to Allonnia (Boston, Mass.; www.allonnia.com), the company distributing the technology in North America.
PFAS compounds greater than C6 are amphiphilic, with a hydrophilic head and hydrophobic tail. SAFF takes advantage of this property by bubbling air through the PFAS-containing water such that the PFAS molecules accumulate at the air-water interface. The water to be decontaminated enters a series of reactors with air bubbling through and the PFAS is carried along with the bubbles. The key parameters for effective separation are the dynamics of the tank configuration, the size of the air bubbles and the rate of air introduction, says Nicole Richards, CEO of Allonnia.
Typical PFAS contaminant levels in water samples can range from 200 to 50,000 parts per trillion (ppt) or more, and the SAFF concentrator can reduce PFAS levels down to a few parts per trillion, Richards notes.
SAFF process units are mounted on movable trailers and can be used temporarily at sites for removing PFAS from groundwater, landfill leachate, process water and other water sources, Richards explains. SAFF units are designed to be coupled with a PFAS-destruction technology, such as “PFAS destruction using supercritical water,” Chem. Eng., March 2022, p. 8.
SAFF technology works with all PFAS molecules with six or more carbon atoms, but is not as effective for short-chain PFAS compounds, so Allonnia is working on adding a bio-surfactant to the SAFF system to pick up shorter chains.