Field Demonstration of a High‐Frequency Ultrasonic Treatment Reactor for PFAS Destruction in Contaminated Groundwater

Abstract Firefighting foams containing per‐ and polyfluoroalkyl substances (PFAS) have been extensively used for fire training and emergency responses at Air Force sites. The use of these foams has resulted in PFAS contamination in groundwater, surface water, and soils. Current field‐scale treatment of PFAS impacted water has mostly been limited to concentration technologies. These methods do not destroy PFAS but create secondary, more concentrated waste. Hence, an innovative on‐site remedial method is crucial to treat/destroy PFAS in high concentration waste streams. A field demonstration was conducted at a DOD site in Nebraska where PFAS‐impacted groundwater was pumped into a mobile ultrasound treatment trailer, and PFAS were desorbed and degraded by localized cavitation at high pressures and temperatures. The maximum degradation efficiency was observed to be 91%, while the lowest degradation efficiency was 68%. The average long‐chain PFAS degradation was 90% compared to 78% for short‐chain PFAS, while for PFAS precursors, degradation was observed to be 76%. The average decrease in measured AOF after treatment was 63%, indicating destroyed PFAS were likely being mineralized without the formation of excess by‐products. Overall, this ultrasonic treatment methodology has demonstrated the ability to treat highly contaminated groundwater in source zones, upstream of sensitive environments or resources.