Bench Scale Studies of Novel In situ Aquifer Remediation of Recalcitrant Fluorinated Organic Compounds at Superfund Sites

Project Summary Abstract Poly and perfluoroalkyl substances PFAS in soil and groundwater are currently remediated by extracting the contaminated groundwater for ex situ treatment via adsorption onto granular activated carbon GAC or other sorbents which only transfers contaminants to another media that still needs to be treated This is a very long term and expensive process because it takes decades for the sorbed PFAS on soil to be extracted via groundwater pump and treat Pandamp T and the carbon must be changed frequently and treatment by high temperature regeneration or incineration is costly In addition Pandamp T technology may never achieve EPA Health Advisory concentrations in the aquifer PFAS are fluorinated anthropogenic pollutants that the USEPA and global health organizations have identified as toxic persistent bioaccumulative and highly recalcitrant being largely resistant to hydrolysis photolysis and biodegradation PFAS were used in many products including aqueous film forming foams to combat chemical fires The use of these foams at military and civilian fire training areas represents a common source of PFAS to the environment They have been identified in surface waters and they persist in groundwater years after use and are mobile in the subsurface contaminating and threatening drinking water supplies As of the U S Department of Defense alone has identified fire crash training sites alone that potentially have PFAS contamination Thus there is a critical need for a more cost effective and in situ remediation approach for remediating PFAS contaminated sites that will only increase in the coming years Our team will further develop and demonstrate an innovative combined in situ ex situ technology to cost effectively expedite treatment of PFAS at Superfund sites The proposed treatment train combines a non toxic cyclic sugar CS to flush sorbed PFAS from the in situ soil extraction of the CS PFAS complex with groundwater and treatment in a high efficiency removal ex situ reactor that simultaneously degrades removes and concentrates times the PFAS ultimate on site destruction by alkaline ozonation removal and returns the treated water with low concentration CS amendment to injection wells for continued flushing The ex situ treatment reactor can also be used as pre treatment to existing GAC Bench scale tests will be used to evaluate those parameters needed to optimize PFAS desorption from soil destruction of the extracted CS PFAS complex in the ex situ reactor and ultimate destruction of the PFAS concentrate by alkaline ozonation Batch soil column and small scale multi staged diffused gas reactor experiments are planned Test conditions include varying CS and oxidant concentrations flowrates pH residence time and PFAS removal rates Design of a site specific field pilot test for PFAS treatment with estimated costs will be prepared This Project will further develop and demonstrate an innovative combined in situ ex situ remedial technology for treatment of poly and perfluoroalkyl substances PFAS in contaminated soil and groundwater at Superfund sites There is a pronounced need for a cost effective and efficient in situ treatment process to expedite achievement of the EPA Health Advisory concentrations in groundwater supplies because current ex situ pump and treat technology is long term costly and may never achieve the low regulatory concentrations in the aquifer due slow desorption of the PFAS from soil Based on the laboratory data acquired in the Phase I study the design of a site specific field pilot test for PFAS treatment with estimated costs will be prepared for the Phase II proposal