Formatted Title
In Situ and Ex Situ Destruction of PFAS Using a Novel Approach to Catalyzed Chemical Oxidation
Background/Objectives
Per- and polyfluoroalkyl substances (PFAS) have been in widespread use in the consumer product stream since the 1950s, appearing in consumer products ranging from fire-fighting foam to plastics and fabrics to food packaging and cosmetics. As a result, PFAS are contaminants of concern globally, appearing on tens of thousands of sites and effecting all industries. PFAS molecules are difficult to address in natural media, tend to be highly recalcitrant in the environment and are termed in mass media as forever chemicals. Currently there are no widely available remedial technologies that have been demonstrated to destroy PFAS in situ and destructive ex situ options are limited to high-cost solutions oriented toward high concentration waste streams. Our objective is to develop a low cost means to address PFAS impacts in-situ in soil and groundwater by destroying the offending PFAS mass in situ. A secondary objective is to develop a low-cost mechanism to destroy PFAS in ex-situ settings at concentrations ranging up to two to three milligrams per liter
Approach/Activities
Parsons has conducted multiple lab-scale studies and ex situ field trials using PFAS-impacted matrices (soil and groundwater) from client sites in Michigan, New York, and North Carolina to develop a technology capable of degrading PFAS through low-energy chemical means. This innovative patent pending means to degrade PFAS in soil and groundwater was achieved by combining a small temperature rise, a unique metals-based catalyst, and off-the-shelf oxidant products. All analysis for parameters such as PFAS, total oxidizable precursor, total organic fluorine and geochemical properties were conducted by third party laboratory to ensure study result validity.
Results/Lessons Learned
The applied metal-catalyzed oxidant was capable of achieving PFAS destruction efficiencies in the laboratory of greater than 99.9% within method detection limits and greater than 90% destruction efficiency during large volume mixed matrix ex situ field trials. We have learned that certain aspects of the technology such as catalyst/oxidant loading, temperature and injection methodology play a key role in achieving PFAS destruction. Laboratory and field ex situ demonstrations across a wide variety of groundwater and soil conditions, PFAS mixes, and co-contaminants has yielded a tremendous collection of lessons learned and a much deeper understanding of PFAS destruction mechanisms. In this presentation we will: 1) showcase some of the results obtained through our bench-scale and ex situ field pilot studies; 2) discuss the underlying mechanism responsible for PFAS degradation; and 3) shed light on the applicability of the technology for in situ and ex situ PFAS degradation.