Alternative PFAS Treatment in a commingled groundwater plume
A groundwater collection system was installed at a former industrial site to capture impacted groundwater. Final design of the treatment system was postponed to allow the operational system discharge to the local POTW to be monitored and used to refine the influent concentrations and flow rate for final design. The monitoring and conceptual treatment design was focused on phosphorus, iron and oil and grease with the goal to develop treatment for a direct discharge under a National Pollutant Discharge Elimination System (NPDES) Permit. During the monitoring period, it was determined that the collected groundwater should also be sampled for PFAS given its heightened regulatory attention. Because the previously proposed treatment system could not treat PFAS the discovery of PFAS has put a temporary halt on any further design or construction of a final environmental remedy. The original groundwater treatment design was abandoned and a new evaluation has been initiated to identify cost-effective treatment options for PFAS and the co-contaminates present in the groundwater. In addition, specific attention in evaluating treatment technologies was focused on the possibility that additional PFAS may be added to the list of regulated substances in the future. The treatment train is expected to include iron precipitation/coagulation, solids removal, and PFAS removal. PFAS bench testing included activated carbon adsorption and ion exchange, which have both been implemented for PFAS treatment commercially. However, both technologies result in a PFAS containing residual which may require regeneration, including PFAS destruction through incineration, or careful management in a landfill to prevent re-release to the environment. Therefore, a literature review was conducted to identify new and developing technologies which may result in mineralization of PFAS and avoid residuals management. Additional bench scale studies were performed to further evaluate one of these processes. The session will discuss the use of the bench scale study results and pretreatment field tests to develop a treatment system concept. In addition, the session will discuss steps taken to evaluate system materials and components to determine if they were an inadvertent source of the PFAS impacts. This includes in the groundwater collection system and the typical materials used in the bench scale studies. Materials that could have been a source were either tested or replaced.