Microplastics and PFAS in landfill-wastewater treatment systems: a field study

Landfills and wastewater treatment plants (WWTP) are point sources for many emerging contaminants, including microplastics and per- and polyfluoroalkyl substances (PFAS). Previous studies have estimated the abundance and transport of microplastics and PFAS separately in landfills and WWTPs. In addition, previous studies typically report concentrations of microplastics as particle count/L or count/gram sediment, which do not provide the information needed to calculate mass balances. We measured microplastics and PFAS in four landfill-WWTP systems in Illinois, USA, and quantified mass of both contaminants in landfill leachate, WWTP influent, effluent, and biosolids. Microplastic concentrations in WWTP influent were similar in magnitude to landfill leachates. In contrast, PFAS concentrations were higher in leachates than WWTP influent. After treatment, both contaminants were detected in WWTP effluent and biosolids, with high prevalence of both contaminants in the biosolids. We concluded that WWTPs reduce PFAS and microplastics, lowering concentrations in the effluent that is discharged to nearby surface waters. However, partitioning of both contaminants to biosolids has implications for further use of biosolids in land applications.垃圾填埋场与污水处理厂（WWTP）是多种新兴污染物的点源，其中包括微塑料与全氟和多氟烷基物质（PFAS）。既往研究多分别针对垃圾填埋场和污水处理厂内的微塑料与PFAS的丰度及迁移行为展开评估。此外，既往研究通常将微塑料浓度报告为粒子数/升或沉积物每克粒子数，这类数据无法提供计算质量平衡所需的信息。我们在美国伊利诺伊州的4套填埋场-污水处理厂联用系统中开展采样检测，定量分析了垃圾渗滤液、污水处理厂进水、出水及生物固体中的两类污染物质量。污水处理厂进水中的微塑料浓度水平与垃圾渗滤液相近；与之相反，垃圾渗滤液中的PFAS浓度高于污水处理厂进水。经处理后，两类污染物均在污水处理厂出水与生物固体中被检出，且二者在生物固体中的检出率均较高。我们的研究结论表明，污水处理厂可有效去除PFAS与微塑料，降低排入周边地表水体的出水污染物浓度。但两类污染物向生物固体的分配行为，会对生物固体后续的土地利用产生影响。