Hydrothermal carbonization (HTC) is an effective way to harmlessly dispose municipal sludge (MS). This work comprehensively reviewed critical hydrothermal parameters of HTC, reaction mechanisms, physicochemical characteristics, applications of target products, technology coupling, energy balance, economic evaluation and life cycle analyses. The formation of hydrochar is predominantly attributed to the polymerization of remarkably reactive intermediates generated through the degradation of biopolymers in MS, as well as the solid-solid conversion of their insoluble components. Physicochemical properties of target products are closely related to process parameters and chemical compositions of MS, which provide a promising opportunity to acquire desired products by optimizing reaction conditions. The combination of other wastes with MS, and the coupling of different processes (e.g., pyrolysis) are potential optimization methods of HTC. The synergy of technological coupling enables the augmentation of value within the product. Typical energy balances of HTC indicate that net energy recovery exists even when the moisture content of municipal sludge is up to 91%. The combination of hydrochar as a substitute for fossil fuels and anaerobic digestion or recycling of process water is very favorable for the life cycle assessment of HTC of MS. Ultimately, some prospects for HTC of MS are highlighted.

水热碳化（HTC）是城市污泥（MS）无害化处理的有效方法。该工作全面综述了HTC的关键水热参数、反应机理、理化特性、目标产品的应用、技术耦合、能量平衡、经济评价和生命周期分析。水炭的形成主要归因于生物聚合物在MS中的降解产生的具有显着反应活性的中间体的聚合，以及其不溶性组分的固-固转化。理化性质目标产物的变化与质谱的工艺参数和化学成分密切相关，这为通过优化反应条件获得所需产物提供了良好的机会。其他废物与MS的结合，以及不同过程（例如热解）的耦合是HTC潜在的优化方法。技术耦合的协同作用可以增加产品的价值。HTC的典型能量平衡表明，即使市政污泥含水率高达91%，也存在净能量回收。氢炭作为化石燃料替代品与厌氧消化或工艺水回收的结合对于MS的HTC生命周期评估非常有利最终，HTC MS 的一些前景被凸显。