show Abstracthide AbstractPerfluoroalkyl substances (PFASs) are persistent and ecotoxic chemicals in aquatic environments. To date, little is known about measures for strengthening PFAS removal in constructed wetlands (CWs). In this study, the removal of the target PFASs perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) was thoroughly investigated in vertical subsurface flow CWs, especially the role of iron oxide and iron-reducing bacteria (FeRB) in the substrate.