Thermal and hydrothermal treatments are promising techniques for sewage sludge management that can potentially facilitate safe waste disposal, energy recovery, and nutrient recovery/recycling. Content and speciation of heavy metal in the treatment products affect the potential environmental risks upon sludge disposal and/or use of the treatment products. Therefore, it is important to study the speciation transformation of heavy metals and the effects of treatment conditions. By combining synchrotron X-ray spectroscopy/microscopy analysis and sequential chemical extraction, this study systematically characterized the speciation of Zn and Cu in municipal sewage sludges and their chars derived from pyrolysis (a representative thermal treatment technique) and hydrothermal carbonization (HTC; a representative hydrothermal treatment technique). Spectroscopy analysis revealed enhanced sulfidation of Zn and Cu by anaerobic digestion and HTC treatments, as compared to desulfidation by pyrolysis. Overall, changes in the chemical speciation and matrix properties led to reduced mobility of Zn and Cu in the treatment products. These results provide insights into the reaction mechanisms during pyrolysis and HTC treatments of sludges and can help evaluate the environmental/health risks associated with the metals in the treatment products.

热处理和水热处理是用于污水污泥管理的有前途的技术，可以潜在地促进废物的安全处置，能量回收以及养分的回收/再循环。处理产物中重金属的含量和种类会影响污泥处置和/或使用处理产物时的潜在环境风险。因此，重要的是研究重金属的形态转化和处理条件的影响。通过将同步加速器X射线光谱法/显微镜分析与顺序化学提取相结合，本研究系统地表征了城市污水污泥中锌和铜的形态以及其从热解（一种代表性的热处理技术）和水热碳化（一种代表性的碳）中衍生出来的焦炭。水热处理技术）。光谱分析显示，与通过热解脱硫相比，通过厌氧消化和HTC处理可增强Zn和Cu的硫化。总体而言，化学形态和基质性质的变化导致处理产品中Zn和Cu的迁移率降低。这些结果提供了对热解和HTC处理污泥过程中反应机理的见解，并可以帮助评估与处理产品中的金属相关的环境/健康风险。