Microbial degradation of PFAS for remediation of contaminated soil and groundwater (bioPFAS)

Description

Per- and polyfluoroalkyl substances (PFAS) include a large group of man-made chemicals, many of which are extremely persistent and also mobile in the environment. Point sources for PFAS exist worldwide and include firefighting training areas and airports. Sweden has more than 2000 potential PFAS sites and more than half of Sweden’s municipalities have PFAS in their raw water for drinking water production.

Remediation of PFAS contaminated sites is hampered by a lack of cost-efficient techniques for in-situ or on-site PFAS degradation. Microbial degradation is an environmentally friendly technology and a key process for the removal of many organic contaminants form the environment, but for PFAS there is a lack of knowledge about the degradation processes and the organisms involved.

Natural degradation of many PFAS is deemed to be very slow, and there is still an open question if complete defluorination can be achieved by natural degradation processes, particularly for fully fluorinated PFAS. However, under controlled conditions in the laboratory at least one bacterial strain has shown capability of degrading fully fluorinated substances such as PFOS and PFOA in cometabolic processes. There is thus initial evidence that under the right conditions microbial degradation of PFAS occurs. Incomplete degradation of PFAS that potentially produces more mobile substances can occur both under natural and stimulated conditions. Improved knowledge of PFAS biodegradation is therefore necessary to understand PFAS mass transport from contaminated hotspots and associated risks.

If conditions can be achieved that enable and stimulate PFAS degradation to a sufficient extent in plumes in groundwater or in contaminated soil, then microbial PFAS degradation can potentially be developed into a useful and cost-efficient technique for PFAS remediation (or that contributes to remediation) at numerous contaminated sites in Sweden and all over the world. If only degradation at a slow rate is achievable, a combined use of sorbents that slow down the PFAS transport together with biodegradation may be advantageous. This project aims to apply microbial degradation of PFAS as a green technology for remediation of soil and groundwater and specifically answer the following questions:

• To what extent can PFAS be microbially degraded in soil and groundwater, which PFAS are degraded and is the degradation complete or incomplete?
• Which environmental factors govern microbial degradation of PFAS and can favorable conditions for microbial degradation of PFAS be achieved or stimulated at contaminated sites in Sweden?