In a municipal wastewater treatment plant, the thermal treatment of sludge can be an efficient way of increasing the final sludge cake dryness and boosting anaerobic digestion performances. However, such treatments generate refractory compounds which, once returned to headworks, can affect the quality compliance of effluent discharges, particularly concerning organic nitrogen. This study explores the effects of thermal hydrolysis (TH) and hydrothermal carbonization (HTC) of municipal sludge on the refractory organic compound production. A novel approach using ultra-performance liquid chromatography with size-exclusion chromatography and UV/fluorescence detection (UPLC-SEC-UV/Fluo) was employed to characterise recalcitrant dissolved organic matter (rDOM), which typically consists of Maillard reaction products (MRP). Specifically, UPLC-SEC-UV/Fluo was combined with principal component analysis (PCA) to enable a more thorough examination of the chemical diversity of MRPs produced. Greater temperatures during the thermal treatment step lead to increased production of rDOM and rDON. Protein-rich sludge with a great AS:PS ratio yields the greatest rDOM levels. MRP characteristics, such as molecular weight distribution and aromaticity, are primarily influenced by temperature and plant origin. UPLC-SEC-UV/Fluo provides information on the structures of MRPs useful to optimize the thermal treatment process and in understanding their fate in subsequent processes (chemical oxidation, biodegradation).

中文翻译：

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污水污泥的热处理：污泥类型和来源对顽固化合物形成的影响


在城市污水处理厂中，污泥的热处理是提高最终污泥饼干燥度和提高厌氧消化性能的有效方法。然而，这种处理会产生难降解化合物，这些化合物一旦返回进水口，就会影响污水排放的质量合规性，尤其是有机氮。本研究探讨了城市污泥的热水解 （TH） 和水热碳化 （HTC） 对难降解有机化合物生产的影响。采用超高效液相色谱结合尺寸排阻色谱和紫外/荧光检测 （UPLC-SEC-UV/Fluo） 的新方法来表征顽固溶解有机物 （rDOM），其通常由美拉德反应产物 （MRP） 组成。具体而言，将 UPLC-SEC-UV/Fluo 与主成分分析 （PCA） 相结合，以便更全面地检查所产生的 MRP 的化学多样性。热处理步骤中较高的温度会导致 rDOM 和 rDON 的产生增加。富含蛋白质的污泥具有较高的 AS：PS 比值，可产生最高的 rDOM 水平。MRP 特性，例如分子量分布和芳香性，主要受温度和植物来源的影响。UPLC-SEC-UV/Fluo 提供有关 MRP 结构的信息，有助于优化热处理过程并了解它们在后续过程（化学氧化、生物降解）中的命运。