Landfill leachate is often an important source of emerging organic contaminants including perfluoroalkyl and polyfluoroalkyl substances (PFASs) requiring proper treatment to protect surface water and groundwater resources. This study investigated the occurrence of PFASs in the leachate of a capped landfill site in Singapore and the efficacy of PFASs removal during flow through a constructed wetland (CW) treatment system. The CW treatment system consists of equalization tank, aeration lagoons, sedimentation tank, reed beds and polishing ponds. Target compounds included 11 perfluoroalkyl acids (PFAAs) (7 perfluoroalkyl carboxylic acids (PFCAs) and 4 perfluoroalkane sulfonates (PFSAs)) and 7 PFAA precursors. Although total PFASs concentrations in the leachate varied widely (1269 to 7661 ng/L) over the one-year sampling period, the PFASs composition remained relatively stable with PFCAs consistently being predominant (64.0 ± 3.8%). Perfluorobutane sulfonate (PFBS) concentrations were highly correlated with total PFASs concentrations and could be an indicator for the release of PFASs from this landfill. The release of short-chain PFAAs strongly depended on precipitation whereas concentrations of the other PFASs appeared to be controlled by partitioning. Overall, the CW treatment system removed 61% of total PFASs and 50–96% of individual PFASs. PFAAs were removed most efficiently in the reed bed (42–49%), likely due to the combination of sorption to soils and sediments and plant uptake, whereas most of the PFAA precursors (i.e. 5:3 fluorotelomer carboxylate (5:3 acid), N-substituted perfluorooctane sulfonamides (N-MeFOSAA and N-EtFOSAA)) were removed in the aeration lagoon (>55%) by biodegradation. The sedimentation tank and polishing ponds were relatively inefficient, with only 7% PFASs removal.

中文翻译：

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在处理垃圾渗滤液的大规模热带人工湿地系统中去除全氟烷基和多氟烷基物质

垃圾渗滤液通常是新兴的有机污染物的重要来源，包括全氟烷基和多氟烷基物质（PFAS），需要对其进行适当处理以保护地表水和地下水资源。这项研究调查了新加坡有盖垃圾填埋场渗滤液中PFAS的发生情况，以及在流经人工湿地（CW）处理系统的过程中去除PFAS的功效。连续水处理系统包括均衡池，曝气池，沉淀池，芦苇床和抛光池。目标化合物包括11种全氟烷基酸（PFAA）（7种全氟烷基羧酸（PFCA）和4种全氟烷磺酸盐（PFSA））和7种PFAA前体。尽管在一年的采样期内，渗滤液中的PFAS总浓度变化很大（1269至7661 ng / L），PFAS的组成保持相对稳定，而PFCA始终占主导地位（64.0±3.8％）。全氟丁烷磺酸盐（PFBS）的浓度与PFAS的总浓度高度相关，并且可能是该填埋场中PFAS释放的指标。短链PFAAs的释放强烈依赖于降水，而其他PFAS的浓度似乎受分配控制。总体而言，连续波处理系统去除了全部PFAS的61％和单个PFAS的50-96％。PFAA在芦苇床上的去除效率最高（42–49％），这可能是由于对土壤和沉积物的吸附以及植物吸收的综合作用，而大多数PFAA前体（即5：3含氟调聚物的羧酸盐（5：3酸） ，N-取代的全氟辛烷磺酰胺（N-MeFOSAA和N-EtFOSAA）在曝气池（> 55％）中通过生物降解去除。沉淀池和抛光池效率相对较低，仅去除了7％的PFAS。