Department of Environmental, Water and Earth Science, Tshwane University of Technology, Private Bag X680, Pretoria, 0001, South Africa.
Department of Environmental, Water and Earth Science, Tshwane University of Technology, Private Bag X680, Pretoria, 0001, South Africa.
J Environ Manage. 2020 Feb 1;255:109945. doi: 10.1016/j.jenvman.2019.109945. Epub 2019 Dec 26.
In this study, the efficiencies of selected wastewater treatment plants (WWTPs) to remove selected perfluoroalkyl substances (PFASs) during wastewater treatment processes were evaluated. For this purpose, influent samples from Daspoort, Zeekoegat and Phola WWTPs, were initially screened for the presence of sixteen different PFASs of which only seven were detected. These include: perfluorobutanoic acid (PFBA), perfluoro-n-pentanoic acid (PFPeA), perfluorohexanoic acid (PFHxA), perfluorooctanoic acid (PFOA), perfluorodecanoic acid (PFDA), perfluorohexane sulfonate (L-PFHxS), and perfluorooctane sulfonate (L-PFOS). To determine the concentrations of these PFASs, wastewater samples were subjected to solid-phase extraction followed by liquid chromatography-tandem mass spectrometry. The results showed that L-PFOS was the dominant compound with the highest concentration of 508 ± 258 ng/L at Daspoort WWTP. Overall, the three WWTPs could not achieve the complete influent-to-effluent removal of the PFASs and the best removals were observed at Zeekoegat WWTP. The removal efficiency of the different unit processes varied from one plant to another and also from each type of PFASs. At Daspoort, the removal efficiency of the primary settling tanks was poor and the highest removal reached 39% for PFHxA. The activated sludge (AS) of this WWTP achieved the highest removal of 84% for the L-PFOS. At Zeekoegat, the AS achieved the highest removal of 94% for the L-PFOS. The anaerobic pond at Phola achieved a higher removal of 80% for the L-PFOS. However, no removal was observed downstream of the biological filter for the same compound. Poor removal efficiency was reported downstream of the wetland at Phola except for the PFOA (16%).
在这项研究中，评估了选定的废水处理厂（WWTP）在废水处理过程中去除选定的全氟烷基物质（PFAS）的效率。为此，对 Daspoort、Zeekoegat 和 Phola WWTP 的进水样本进行了初步筛选，以确定是否存在 16 种不同的 PFAS，其中只有 7 种被检测到。这些包括：全氟丁烷酸（PFBA）、全氟正戊酸（PFPeA）、全氟己酸（PFHxA）、全氟辛酸（PFOA）、全氟癸酸（PFDA）、全氟己烷磺酸（L-PFHxS）和全氟辛烷磺酸（L-PFOS）。为了确定这些 PFAS 的浓度，对废水样本进行了固相萃取，然后进行液相色谱-串联质谱分析。结果表明，L-PFOS 是主要化合物，在 Daspoort WWTP 的浓度最高，为 508±258ng/L。总体而言，这三个 WWTP 无法实现 PFAS 的完全进水到出水去除，在 Zeekoegat WWTP 观察到最佳去除效果。不同单元过程的去除效率因工厂而异，也因每种 PFAS 类型而异。在 Daspoort，初沉池的去除效率很差，PFHxA 的去除效率最高达到 39%。该 WWTP 的活性污泥（AS）对 L-PFOS 的去除率最高，达到 84%。在 Zeekoegat，AS 对 L-PFOS 的去除率最高，达到 94%。Phola 的厌氧塘对 L-PFOS 的去除率达到 80%。然而，对于相同的化合物，在生物过滤器下游没有观察到去除。Phola 的湿地下游报道的去除效率较差，除了 PFOA（16%）。
