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Presentation Slides


“Application of Non-Thermal Plasma Technology for the Removal of PFAS from Investigation-Derived Wastes” by Dr. Chris Sales (ER18-1570)

A variety of non-equilibrium plasma technologies have emerged as promising methods for destruction of PFAS. All these technologies rely on the highly reactive environments created in plasma discharges (i.e., when ionized gases are formed by applying an electric current with sufficient voltage) for degrading PFAS. Depending on the plasma gas mixture and type of discharge, several different mechanisms could be involved in the degradation of PFAS by plasma, including reactive chemical species (e.g., electrons), visible and ultraviolet light, and heat. This presentation will focus on a SERDP project investigating the use of non-equilibrium gliding arc plasma (GAP) discharges to degrade PFAS in liquid and solid matrices. We will present the findings from ongoing efforts to (1) identify what degradation products are formed and what mechanisms are involved during GAP treatment of PFAS, (2) characterize how co-contaminants and other characteristics of the matrix impact degradation kinetics, and (3) examine the feasibility and energy and resource costs for scaling-up GAP technology for treatment of PFAS-contaminated matrices.

“Rapid and Inexpensive Delivery of Particulate Carbon for In Situ PFAS Treatment in Groundwater” by Dr. Stephen Richardson (ER22-7363)

To date, granular activated carbon (GAC) has been the method of choice for ex situ treatment of PFAS-impacted groundwater from pump and treat systems. In situ treatment of PFAS is less common, although several case studies with particulate carbon amendments (PCAs) have yielded promising results. The geotechnical industry offers a variety of well-established techniques for quickly and efficiently accessing the subsurface for the purposes of ground stabilization, foundation rehabilitation, porewater drainage, and structural support. The speed and efficiency of these techniques are advantageous to the field of environmental remediation, particularly for emplacement of remedial amendments (e.g., PCAs, zero valent iron [ZVI], vegetable oil, oxidants) into the subsurface at contaminated sites. For this ESTCP project, our goal is to repurpose a commercially available geotechnical technology, the “Grout Bomber,” for enhanced delivery of GAC for in situ retention of PFAS in groundwater. The Grout Bomber can efficiently deliver large quantities of GAC into the subsurface, forming arrays of closely spaced permeable sorbent columns perpendicular to groundwater flow. This technology aims to deliver more sorbent per unit area than injection-based sorbent barriers, increase the reliability of these barriers by using closely spaced sorbent columns, and reduce the cost of sorbent barriers at many sites.

Speaker Biographies

Dr. Christopher Sales is an associate professor in the Civil, Architectural, and Environmental Engineering Department at Drexel University, with research expertise in environmental microbiology, environmental biotechnologies, and environmental remediation technologies. He is also director of the Applied Plasma Biology and Chemistry Laboratories at the C&J Nyheim Plasma Institute of Drexel University, where he leads efforts on the research and development of innovative non-thermal plasma technologies for agriculture, food safety, public health, medicine, and environmental applications. Dr. Sales received a bachelor’s of engineering degree in chemical and biomolecular engineering and a bachelor’s in environmental studies from the University of Pennsylvania. He received his master’s and doctoral degrees in civil and environmental engineering from the University of California, Berkeley.

Dr. Stephen Richardson is a vice president and principal engineer at GSI Environmental in Austin, Texas. He has served as a PI and co-PI on projects funded by SERDP, ESTCP, the Department of Energy, the Air Force Civil Engineer Center, the National Defense Center for Energy and Environment, and the Naval Facilities Engineering System Command on topics including PFAS fate and transport, innovative technologies for PFAS remediation, amendment emplacement in low-permeability zones, and bioremediation and abiotic degradation of chlorinated solvents. He has authored or co-authored over 30 peer-reviewed journal articles and is a licensed professional engineer in Texas, North Carolina, Louisiana, and Alberta (Canada). Dr. Richardson received a bachelor’s degree from the University of Waterloo, a master’s degree from Louisiana State University, and a doctoral degree in environmental engineering from the University of North Carolina at Chapel Hill.