Granular activated carbon (GAC) has been proposed for use or is being used at many sites to specifically remove perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) from impacted water in ex situ processes; however, the cost-effectiveness of GAC systems and the ability to treat all PFAS in such systems remains questionable. SERDP and ESTCP are funding the development of modifications to existing sorbents, as well as the identification of new sorbents that may remove PFAS more selectively from impacted waters. Integral to the use of GAC and some of these new sorbents is the generation of ancillary waste streams such as brines. Solutions for regeneration of spent media, and treatment and disposal of ancillary waste streams are components of this research area.