Thermal treatments of phosphorus (P)-rich sewage sludge for efficient P reclamation have recently gained much attention. Our recent research proposed a low-temperature combustion method that can simultaneously target safe waste disposal, fly ash volume reduction, heavy-metal stabilization, P recovery, and energy reuse. To further optimize treatment conditions and gain deeper insights into P speciation, this study systematically characterized P transformation during low-temperature co-combustion of sewage sludge with biowaste by combining X-ray absorption spectroscopy, sequential extraction, and nuclear magnetic resonance spectroscopy analyses. Organic P, phytic acid, and pyrophosphate in the raw feedstock transformed into orthophosphate during low-temperature combustion. With increasing mass fraction of biowaste, low-temperature co-combustion increased the relative abundance of Ca-associated P and decreased the abundance of Fe-associated P. The dominant P species in the produced bottom ash is strongly correlated to the amount and speciation of metals in the feedstock and their affinities to P. The introduction of biowaste altered the enrichment efficiency and availability of P in the ash. The results from this study revealed the effects of combustion conditions and feedstock characteristics on P speciation and provided a fundamental basis for guiding the optimization of the thermal treatment method for eliminating hazardous wastes, reusing energy, and improving P reclamation efficiency.

中文翻译：

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污水污泥与生物废料低温共燃烧时磷的转化

富磷（P）污水污泥的热处理技术，可以有效地进行P的再生，因此备受关注。我们最近的研究提出了一种低温燃烧方法，该方法可同时针对安全废物处置，减少飞灰量，重金属稳定化，磷回收和能源再利用的目标。为了进一步优化处理条件并更深入地了解P形态，本研究通过结合X射线吸收光谱，顺序萃取和核磁共振光谱分析，系统地表征了污水污泥与生物废料的低温共燃烧过程中的P转化。在低温燃烧过程中，原料中的有机P，植酸和焦磷酸盐转化为正磷酸盐。随着生物废物质量分数的增加，低温共燃烧增加了钙相关磷的相对丰度，并降低了铁相关磷的丰度。产生的底灰中的主要磷种类与原料中金属的含量，形态以及它们的亲和力密切相关。生物废物的引入改变了灰分中磷的富集效率和利用率。这项研究的结果揭示了燃烧条件和原料特性对磷形态的影响，并为指导优化热处理方法以消除有害废物，再利用能源和提高磷回收效率提供了基础。产生的底灰中占优势的P种类与原料中金属的含量和形态以及它们与P的亲和力密切相关。生物废物的引入改变了P在灰中的富集效率和可用性。这项研究的结果揭示了燃烧条件和原料特性对磷形态的影响，并为指导优化热处理方法以消除有害废物，再利用能源和提高磷回收效率提供了基础。产生的底灰中占优势的P种类与原料中金属的含量和形态以及它们与P的亲和力密切相关。生物废物的引入改变了P在灰中的富集效率和可用性。这项研究的结果揭示了燃烧条件和原料特性对磷形态的影响，并为指导优化热处理方法以消除有害废物，再利用能源和提高磷回收效率提供了基础。