Background
Groundwater from a collection system at the former General Motors (GM) Powertrain manufacturing facility site at Willow Run in Ypsilanti, Michigan contains high levels of per and polyfluoroalkyl substances (PFAS). Conventional treatment technologies for the detected PFAS were evaluated in order to develop a cost-effective treatment process, which included granular activated carbon (GAC). Both PFOS and PFOA are present in the groundwater at Willow Run. However, only PFOS with average concentration of 308 ppt in the groundwater is above the current Michigan surface water quality standard (WQS) of 12 ppt. The TOC level in the groundwater of 15-20 mg/L, including high levels of oil and grease (12 mg/L), is of concern, as it will likely drive GAC usage since it is orders of magnitude greater than the total PFAS concentration.
Installation
The environmental firm GHD performed bench studies to compare DEXSORB performance for PFAS removal with GAC in this water matrix. For PFOS breakthrough, DEXSORB treated approximately 50,000 L/kg before a 12 ppt breakthrough occurred. The GAC media treated approximately 2,200 L/kg before a 15 ppt breakthrough occurred. DEXSORB treated approximately 25 times the volume for the same mass of media. From November 2024 to April 2025, Cyclopure ran two 48-inch diameter vessels in series connection, followed by two 24"x72" FRP vessels in parallel connection. Each 48"-diameter vessel is loaded with 300 kg of DEXSORB, each 24"x72" vessel was loaded with 300 kg of DEXSORB.
Since Installation
GHD reported the results of these studies at the 82nd Annual International Water Conference (IWC 2021) in Scottsdale Arizona on November 10, 2021.
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