Sampling of per- and polyfluoroalkyl substances in drainage water from a waste management facility

Per- and polyfluoroalkyl substances (PFAS) have been used for decades in a broad range of consumer products and industrial applications. A variety of waste and products containing PFAS inevitably end up at waste management facilities when they are no longer considered useful. Drainage water samples (n = 157) were collected from eight subsections at a waste management facility in Sweden and analyzed for 23 PFAS and extractable organofluorine (EOF). Two different sampling methods were used, grab sampling (n = 32, without filtration) and composite sampling (n = 8, produced by pooling 16 filtered samples taken at the same subsection). Although PFAS have been studied at waste sites, the information is scarce regarding how the concentrations and homologue profiles could differ within the sites. In this study, we investigated if composite sampling could be an alternative to grab sampling for PFAS monitoring purposes. Herein, the PFAS concentrations ranged from <1 to 22 μg/L; the grab samples showed systematic higher concentrations than their corresponding composite sample. Short-chain perfluoroalkyl sulfonic acids (C₄ and C₅) were the largest contributing sub-class, followed by short-chain perfluoroalkyl carboxylic acids (C₄ to C₆). EOF was measured up to approximately 140 μg/L F with 99% being unexplained by the fluorine mass balance analysis. The results from this study showed that both sampling methods were comparable for target analysis and that 11 compounds represented most of the PFAS concentrations. However, the discrepancy between the sampling methods was greater for EOF analysis and may be due to the preparation of composite samples and/or due to fluctuating discharges during the sampling period. Composite sampling was observed to be comparable to grab sampling for target analysis.