Florida International University, Civil and Environmental Engineering Department, USA.
Florida International University, Applied Research Center, USA.
J Environ Manage. 2024 Nov;370:122395. doi: 10.1016/j.jenvman.2024.122395. Epub 2024 Sep 6.
The land application of biosolids as a management practice is considered a beneficial use for improving crop yield and reducing the need for other fertilizers. PFAS enter wastewater treatment plants through collection networks, including industrial discharges, the use of PFAS-containing products, and runoff. Therefore, PFAS may be present in biosolids derived from sewage sludge. The objectives of this study were to evaluate PFAS levels in biosolids samples collected at two wastewater treatment plants operated by the Miami Dade Water and Sewer Department (MDWASD): (1) the South District Wastewater Treatment Plant (SDWWTP) which received landfill leachate and (2) the Central District Wastewater Treatment Plant (CDWWTP). Sludge samples were collected after thickening, anaerobic digestion, and dewatering processes. The samples were subjected to batch leaching tests for 30 days. After the leaching tests, the PFAS levels in the liquid and solid fractions were analyzed for 40 PFAS. The findings show that during the aeration process (i.e., activated sludge process), PFAS are removed from the wastewater and accumulate on the solids. When the thickened sludge is digested, some PFAS are released to the liquid phase as the volatile solids decompose. During the dewatering process by centrifugation, PFAS that are partitioned to the liquid phase are removed, reducing PFAS content in the dewatered biosolids. Of the 40 PFAS analyzed, 24 were detected in leachate or solid residue samples. Samples from the SDWWTP had higher levels of PFAS due to the contribution from landfill leachate discharged to this facility. The partitioning of PFAS between the liquid phase and solid residue after 30 days of mixing indicates that the majority of PFAS in the biosolids are highly soluble and have a high tendency to be mobilized (by runoff, irrigation, precipitation) after land application. The fate profiles of PFAS biosolids were evaluated in terms of their solubility and retardation characteristics.
将生物固体作为管理措施进行土地应用被认为是一种有益的利用方式，可以提高作物产量并减少对其他肥料的需求。全氟和多氟烷基物质通过收集网络进入废水处理厂，包括工业排放、使用含全氟和多氟烷基物质的产品以及径流。因此，全氟和多氟烷基物质可能存在于源自污水污泥的生物固体中。本研究的目的是评估迈阿密戴德水务和污水署（MDWASD）运营的两个废水处理厂（1）南区废水处理厂（SDWWTP）和（2）中区废水处理厂（CDWWTP）收集的生物固体样本中的全氟和多氟烷基物质水平：（1）接收垃圾渗滤液的废水处理厂，（2）接收工业废水排放、含全氟和多氟烷基物质产品使用和径流的废水处理厂。在浓缩、厌氧消化和脱水过程后采集污泥样本。将样品进行 30 天的批量浸出试验。浸出试验后，分析液体和固体部分的 40 种全氟和多氟烷基物质的含量。研究结果表明，在曝气过程（即活性污泥过程）中，全氟和多氟烷基物质从废水中被去除并在固体上积累。当浓缩污泥被消化时，由于挥发性固体分解，一些全氟和多氟烷基物质会释放到液相中。在通过离心进行脱水过程中，分配到液相中的全氟和多氟烷基物质被去除，从而降低脱水生物固体中的全氟和多氟烷基物质含量。在所分析的 40 种全氟和多氟烷基物质中，有 24 种在浸出液或固体残渣样品中被检出。由于排入该设施的垃圾渗滤液的贡献，SDWWTP 的样品中全氟和多氟烷基物质的含量更高。在混合 30 天后，全氟和多氟烷基物质在液相和固体残渣之间的分配表明，生物固体中的大多数全氟和多氟烷基物质具有高度的水溶性，并且在土地应用后具有很高的被迁移（通过径流、灌溉、降水）的趋势。根据其溶解度和阻滞特性评估了全氟和多氟烷基物质生物固体的命运概况。
