This SERDP and ESTCP webinar highlights advancements in water treatment technologies for PFAS destruction. Two SERDP investigators will introduce different approaches to eliminating PFAS from groundwater and aqueous investigation derived waste (IDW). Specifically, they will explore the use of electrochemical membrane technology for PFAS oxidation and plasma treatment processes for IDW.
“Electrochemical Oxidation of PFAS Using a Novel Reactive Electrochemical Membrane Technology” by Dr. Brian Chaplin
Electrochemical advanced oxidation processes (EAOPs) have emerged as promising water treatment technologies for the elimination of per- and polyfluoroalkyl substances (PFAS). Progress has been facilitated by the development of novel, stable electrode materials that efficiently promote the rate-determining direct oxidation of PFAS, which occurs at very high anodic potentials. This presentation discusses ongoing research efforts aimed at advancing EAOPs for PFAS oxidation in contaminated groundwater utilizing a novel reactive electrochemical membrane (REM) technology.
Specific technical objectives include: (1) development of REMs for destructive PFAS removal in synthetic and real groundwater samples; (2) determination of the optimal operational mode of this technology; and, (3) calculation of energy requirements for the REM-based system for comparison to other technologies. A specific focus on treatment of PFOS and PFOA was made, which allowed comparison of results to the existing literature.
Results indicate that the REM was successful at reducing PFAS from initial concentrations in the milligram per liter (mg/L) to microgram per liter (µg/L) range to the nanogram per liter (ng/L) range, where the exact operational mode was dependent on solution conditions. We will discuss the challenges and limitations associated with this technology to establish a realistic vision of a REM-based remediation technology for PFAS removal. Overcoming these challenges is the focus of ongoing research, which will enable pilot-scale testing to further validate this new technology.
“Plasma Based Treatment Processes for PFAS Investigation Derived Waste” by Dr. Thomas Holsen
This presentation highlights SERDP efforts to reduce Department of Defense (DoD) liabilities by developing sustainable, cost-effective technologies to destroy PFAS in aqueous investigation derived waste (IDW). IDW consists of excess soil cuttings, purge water from groundwater sampling, and fluid from decontamination of drilling equipment that are contaminated with PFAS as well as potentially many other traditional contaminants. IDW is typically disposed of offsite at a facility equipped to handle such material, which can increase investigation costs. If the IDW can be treated destructively onsite, the need for transport and disposal offsite can be circumvented.
This SERDP project investigated soil washing of IDW with a combination of water, methanol and sodium chloride followed by treatment of the soil washing solution in a plasma-based reactor to destroy desorbed PFAS. The presentation will describe the results of that work which indicated the following: (1) soil washing with water containing small amounts of methanol and sodium chloride is effective at removing PFAS (although water alone is fairly effective); (2) PFAS are removed from soil quickly (minutes in these experiments); and, (3) plasma treatment from high concentration salt solutions is effective.