Application of a Microporous Polyethylene Tube Passive Sampler for Monitoring Per- and Polyfluoroalkyl Substances in Wastewater Influent and Effluent

The potential of kinetic passive samplers to monitor per and polyfluoroalkyl substance (PFAS) concentrations in wastewater treatment plants (WWTPs) was evaluated using microporous polyethylene tube (MPT) passive samplers containing hydrophilic–lipophilic-balanced (HLB) or weak-anion-exchange (WAX) sorbents. Sampling rates (Rs) from 28 day deployments in WWTP effluent were consistent with principal resistance to PFAS accumulation in wastewater-filled micropores of the polyethylene tube. Considering both sorbents, PFAS Rs in the influent were smaller than in the effluent by a factor of 3.7, attributed to micropore clogging from a colloidal material but not biofilm formation. Combined Isolute ENV+ Rs values in the influent and effluent were 2.1 times larger than for Evolute WAX. Exploring their wider applicability, samplers with Sepra ZT-WAX were deployed in six other WWTPs with varying catchment characteristics. Rs values were significantly greater than those of Evolute WAX, indicating cationic charge center possession alone is an insufficient criterion for sorbent performance. Based on longer linear uptake timespans (e.g., >104 days for PFOA) and provision of time-weighted average concentrations, Evolute WAX was the best sorbent investigated. PFAS concentrations in wastewater derived from MPT samplers gave comparable accuracy to current grab sampling methods (i.e., EPA Method 1633). Findings demonstrate that MPT samplers are useful tools for monitoring PFAS in WWTPs.