The treatment of PFAS has been a topic of discussion among the solid waste industry for the last few years. There have been numerous presentations and articles that touch on currently available technologies or “off the shelf” options as well as innovative technologies. The “off the shelf” technologies until a few years ago were probably never thought to be used for these “forever compounds” but thanks to the affinity of PFAS for these treatment technologies they are being adapted for removal of PFAS from leachate and other liquid waste streams. But why is the science behind PFAS compounds and the treatment technologies so important? If the goal is to remove these ubiquitous compounds from the environment, we need to fully understand the implications of these treatment options relative to the chemical make-up of these compounds.
In general, when considering treatment mechanisms, we have destruction or sorption mechanisms. While destructive technologies would appear to be the preferred approach for the complete removal of PFAS, it is not clear if destruction is partial or complete. If only partial destruction is achieved then you would expect to still have PFAS compounds remaining but those could include the initial compounds being treated and then some derivative (i.e., a new compound). This uncertainty is a result of the strength of the carbon fluorine bond and the possibility that the treatment method only partially breaks the bonds which results in more a transformation of a PFAS compound. Therefore, when thinking about total PFAS concentrations, if only partial destruction occurs this method would still leave PFAS to be managed but transforming the compounds to a different mixture to manage. Sorption mechanisms rely on the affinity for PFAS to a surface to remove that compound from the waste stream. This mechanism ultimately is a concentrating approach that generates a more concentrated waste stream that would require additional management and treatment.
The primary treatment categories currently available for PFAS treatment include thermal and non-thermal destruction and sequestration/solidification. Although there is additional research needed to understand the efficiency of thermal destruction of PFAS compounds, it is thought that under the right conditions (time, temperature, and turbulence) there is enough energy to destroy the carbon fluorine bonds to completely break down PFAS to its elemental components safely. Lastly, sequestration and solidification treatment is being evaluated as a means to immobilize PFAS and sequester them in a repository. This approach would essential remove PFAS from one point of exposure.
But what does this all mean for leachate treatment specifically as regulations continue to evolve? This presentation will discuss the currently available off-the-shelf technologies available to treatment PFAS and the advancements being made to break the bond barrier and go beyond these technologies.
