Perfluorinated compounds (PFCs) are a group of bio-recalcitrant pollutants that remain in waste activated sludge and may subsequently be transferred with sludge to thermal hydrolysis pretreatment (THP) process. Instead of reduction, it is observed previously that the concentration of free PFCs elevated after THP. By employing perfluorooctanoic acid (PFOA) as a representative, this study developed a hierarchical scheme to pinpoint the key factors that contribute to free PFOA elevation from the complex sludge transformations. According to the results, the relative abundance of PFOA in the liquid phase increased by 11.7 – 22.9% during THP. In the solid phase, the amide groups reduction and the spatial structure change of proteins weakened the sorption capability of solids for PFOA. In the liquid phase, the increase of proteins, which could bind and form static hindrance to regulate the behavior of PFOA, was the main factor to retain PFOA in liquid. In contrast, other sludge transformations including changes in pH, zeta potential, ionic condition and specific surface area, displayed insignificant impact on the redistribution process. The study presents a detailed picture on how sludge transformations would regulate PFCs distribution that ultimately direct the selection of further treatment processes.

全氟化合物 (PFC) 是一组残留在废弃活性污泥中的生物难降解污染物，随后可能随污泥转移至热水解预处理 (THP) 过程。先前观察到，THP 后游离 PFC 的浓度不但没有减少，反而升高。本研究以全氟辛酸（PFOA）为代表，开发了一个分层方案，以查明复杂污泥转化过程中导致游离 PFOA 升高的关键因素。结果表明，THP 期间，液相中 PFOA 的相对丰度增加了 11.7 – 22.9%。在固相中，酰胺基团的减少和蛋白质空间结构的变化削弱了固体对PFOA的吸附能力。在液相中，蛋白质增加，它能结合并形成静电位阻来调节PFOA的行为，是PFOA在液体中保留的主要因素。相比之下，其他污泥转化，包括 pH 值、zeta 电位、离子条件和比表面积的变化，对再分配过程的影响并不显着。该研究详细介绍了污泥转化如何调节 PFC 的分布，从而最终指导进一步处理工艺的选择。