Extracellular polymeric substances (EPS) participate in the removal of organic micropollutants (OMPs), but the primary pathways of removal and detailed mechanisms remain elusive. We evaluated the effect of EPS on removal for 16 distinct chemical classes of OMPs during anaerobic digestion (AD). The results showed that hydrophobic OMPs (HBOMPs) could not be removed by EPS, while hydrophilic OMPs (HLOMPs) were amenable to removal via adsorption and biotransformation of EPS. The adsorption and biotransformation of HLOMPs by EPS accounted up to 19.4 ± 0.9 % and 6.0 ± 0.8 % of total removal, respectively. Further investigations into the adsorption and biotransformation mechanisms of HLOMPs by EPS were conducted utilizing spectral, molecular dynamics simulation, and electrochemical analysis. The results suggested that EPS provided abundant binding sites for the adsorption of HLOMPs. The binding of HLOMPs to tryptophan-like proteins in EPS formed nonfluorescent complexes. Hydrogen bonds, hydrophobic interactions and water bridges were key to the binding processes and helped stabilize the complexes. The biotransformation of HLOMPs by EPS may be attributed to the presence of extracellular redox active components (-type cytochromes (-Cyts), -Cyts-bound flavins). This study enhanced the comprehension for the role of EPS on the OMPs removal in anaerobic wastewater treatment.

中文翻译：

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破译细胞外聚合物在厌氧废水处理过程中有机微污染物吸附和生物转化中的作用


细胞外聚合物（EPS）参与有机微污染物（OMP）的去除，但去除的主要途径和详细机制仍然难以捉摸。我们评估了 EPS 在厌氧消化 (AD) 过程中去除 16 种不同化学类别的 OMP 的效果。结果表明，疏水性 OMPs (HBOMPs) 不能被 EPS 去除，而亲水性 OMPs (HLOMPs) 可以通过 EPS 的吸附和生物转化来去除。 EPS 对 HLOMP 的吸附和生物转化分别占总去除量的 19.4 ± 0.9 % 和 6.0 ± 0.8 %。利用光谱、分子动力学模拟和电化学分析，进一步研究了 EPS 对 HLOMP 的吸附和生物转化机制。结果表明 EPS 为 HLOMP 的吸附提供了丰富的结合位点。 HLOMP 与 EPS 中的色氨酸样蛋白结合形成非荧光复合物。氢键、疏水相互作用和水桥是结合过程的关键，有助于稳定复合物。 EPS 对 HLOMP 的生物转化可能归因于细胞外氧化还原活性成分（-型细胞色素（-Cyts）、-Cyts 结合黄素）的存在。这项研究增强了人们对 EPS 在厌氧废水处理中去除 OMP 中的作用的理解。