While the presence of microplastics (MP) has been reported in aquatic habitats across the globe, the pathways through which they enter the environment are still poorly understood. Studies investigating the fate of MP in wastewater are gaining attention but are still scarce, despite the urgent need to understand the role of wastewater treatment plants (WWTP) as point sources of aquatic MP pollution. A likely reason for the limited number of WWTP-associated studies is that working with a biogenic organic matter (BOM)-rich sample matrix like wastewater is challenging. Here, we investigated the presence of MP throughout several stages of a WWTP at multiple depths, employing Fenton’s reagent and focal plane array-based reflectance micro-Fourier-transform infrared spectroscopic (FPA-based reflectance micro-FTIR) imaging, a protocol that allows the automated detection and identification of MP in complex samples with high organic matter content, without the need for previous visual sorting, or reducing considerably the thickness of the sample, or the use of IR-transparent transmission windows. It was found that the number of MP fragments detected at downstream stages of the WWTP notably decreased following the primary settlement stage, with primary settlement stage samples responsible for 76.9% of total MP detected. Despite the marked reduction in the number of MP particles following the primary settlement stage, an average total of 1.5 MP L–1 were identified in the final effluent of the WWTP.

中文翻译：

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使用反射显微 FTIR 成像监测污水处理厂不同阶段的微塑料

虽然在全球水生栖息地中已经报道了微塑料 (MP) 的存在，但它们进入环境的途径仍然知之甚少。尽管迫切需要了解污水处理厂 (WWTP) 作为水生 MP 污染的点源的作用，但调查 MP 在废水中的归宿的研究正在引起关注，但仍然很少。WWTP 相关研究数量有限的一个可能原因是，处理富含生物有机物 (BOM) 的样品基质（如废水）具有挑战性。在这里，我们使用芬顿试剂和基于焦平面阵列的反射微傅立叶变换红外光谱（基于 FPA 的反射微 FTIR）成像，研究了多深度污水处理厂几个阶段中 MP 的存在，该协议允许自动检测和识别具有高有机物含量的复杂样品中的 MP，无需事先目视分选，或显着减少样品的厚度，或使用 IR 透明透射窗口。结果表明，污水处理厂下游阶段检测到的 MP 碎片数量在初级沉降阶段后显着减少，初级沉降阶段样品占检测到的 MP 总量的 76.9%。尽管在初级沉降阶段后 MP 颗粒的数量显着减少，但在污水处理厂的最终出水中发现平均总量为 1.5 MP L-1。或显着减少样品的厚度，或使用红外透明透射窗。发现污水处理厂下游阶段检测到的 MP 碎片数量在初级沉降阶段后显着减少，初级沉降阶段样品占检测到的 MP 总量的 76.9%。尽管在初级沉降阶段后 MP 颗粒的数量显着减少，但在污水处理厂的最终出水中发现平均总量为 1.5 MP L-1。或显着减少样品的厚度，或使用红外透明透射窗。结果表明，污水处理厂下游阶段检测到的 MP 碎片数量在初级沉降阶段后显着减少，初级沉降阶段样品占检测到的 MP 总量的 76.9%。尽管在初级沉降阶段后 MP 颗粒的数量显着减少，但在污水处理厂的最终出水中发现平均总量为 1.5 MP L-1。