Perfluoroalkyl substances concentration from groundwater via direct contact membrane distillation

Abstract

A significant yet largely untapped reservoir of polluted water arises from groundwater, where the diffusion of PFAS has been shown to be alarmingly on the rise, driven by prolonged accumulation and restricted avenues for degradation. Direct contact membrane distillation (DCMD) was used to concentrate and remove perfluorooctanoic acid compounds from contaminated groundwater for the first time using commercially available poly(tetrafluoroethylene) (PTFE) and poly(vinylidene fluoride) (PVDF) membranes. The temporal membrane fouling propensity over the DCMD test was assessed by analysing the morphological and chemical structural changes of the pristine and used membranes. Over 120 h of test using 10 mg/L PFOA-contaminated model groundwater as feed, the PVDF membrane exhibited a lower extent of flux decline of 15% compared to that 43% obtained by PTFE membrane using feed temperature of 60 oC. This study provides a practical route to pre-concentrate the amphiphilic PFAS contaminants from groundwater.