Sewage sludge (SS) formed in wastewater treatment plants can contain organic matter and nutrients in concentrations that are valuable for amending poor soil. This work aims to compare the performance of six residues not only as drying adjuvants of SS but also as improvers agents in agronomic properties of the final product. According to criteria in line with circular economy and industrial ecology, the selected adjuvants were weathered coal fly ash (CFA), bottom biomass ash (BBA), green liquor dregs (GLD), lime mud (LM), eggshell (ES), and rice husk (RH). The main physicochemical properties of these materials were determined. Then, small cylinders with and without 0.15 g adjuvant/g SS_{wet basis} were shaped at room temperature and dried at 130 ºC in a moisture analyzer to evaluate the drying kinetics. The profiles were modeled, and the main parameters determined. Furthermore, several relevant parameters for agronomic applications of the final products were determined, such as pathogen contamination, acid neutralization capacity (ANC), and oxygen uptake rate (OUR). Adding BBA to SS (named as SS_BBA product) promoted the highest diffusion coefficient (2.55·10⁻⁷ m²/s) and drying rate (41.6 g H₂O/kg min). On the other hand, SS_ES showed a positive impact in almost all agronomic parameters, with an ANC of 0.166 g CaCO₃/g, OUR of 10.18 mmol O₂/kg organic matter h, and germination index of 29.1%. In general, the results indicate that several residues can be used to improve not only sludge drying but also the final properties of the product for soil applications.

Graphic Abstract

中文翻译：

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污水污泥与工业残渣结合产品的热脱水性能和农艺性能的改进

污水处理厂中形成的污水污泥 (SS) 可能含有有机物和营养物质，其浓度对于改良贫瘠的土壤很有价值。这项工作旨在比较六种残留物的性能，不仅作为 SS 的干燥助剂，而且作为最终产品农艺特性的改进剂。根据符合循环经济和工业生态的标准，选择的助剂为风化粉煤灰（CFA）、底生物质灰（BBA）、绿液渣（GLD）、石灰泥（LM）、蛋壳（ES）和稻壳（RH）。测定了这些材料的主要理化性质。然后，有和没有 0.15 g 助剂/g SS_湿基的小圆柱体在室温下成型并在水分分析仪中在 130 ºC 下干燥以评估干燥动力学。对剖面进行建模，并确定主要参数。此外，还确定了最终产品农艺应用的几个相关参数，例如病原体污染、酸中和能力 (ANC) 和氧气吸收率 (OUR)。添加BBA 到SS（命名为SS_BBA 产品）促进了最高的扩散系数（2.55·10 ^-7 m ² /s）和干燥速率（41.6 g H ₂ O/kg min）。另一方面，SS_ES 对几乎所有农艺参数都显示出积极影响，ANC 为 0.166 g CaCO ₃ /g，OUR 为 10.18 mmol O ₂/kg有机质h，发芽指数为29.1%。总的来说，结果表明，几种残留物不仅可用于改善污泥干燥，还可用于改善土壤应用产品的最终性能。

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