高含水率是制约污水污泥处理处置的关键因素之一。水热炭化（Hydrothermal carbonization,HTC）是处理高含水物料的有效手段。本文综述了污泥水热炭化机理，对水热炭化固体产物——水热焦（Hydrochar）的脱水干燥特性、燃料及燃烧特性、气化特性、氮磷元素的迁移转化机理、重金属迁移转化机理和典型污水污泥水热炭化工艺能量进行分析。基于吉布斯自由能最小化原理，研究了水热炭化温度和水热炭化时间对水热焦气化特性的影响，发现在200 ℃和30 min时，碳转化率和冷煤气效率分别达到93.9%和64.38%，水热焦气化特性最佳。最后指出，在污水污泥协同水热炭化、磷形态准确分析及定向转化、水热焦气化机理和耦合水热炭化的污泥气化/焚烧工艺能量、经济和环境评价等方面急待开展研究，最终为实现污泥的减量化、能源化和清洁化高效利用提供科学指导。

High moisture content in sewage sludge is one of the obstacles for its disposal. Hydrothermal carbonization (HTC) is an effective and promising approach for the disposal of high moisture content materials, which has attracted more and more researchers' attentions. In this paper, the formation mechanism of hydrochar derived from sewage sludge is summarized. The key issues concerning the hydrochar are discussed in detail, such as dewatering and drying characteristics, hydrochar properties, combustion characteristics, hydrochar gasification characteristics, and transformation and migration of nitrogen, phosphorus and heavy metal during HTC. The energy analysis of typical HTC process is summarized. Based on the theory of Gibbs free energy minimization, the effects of hydrothermal carbonization temperature and time on the gasification performance of hydrochar were studied. It is found that the optimum gasification performance can be achieved at 200 ℃ and 30min with carbon conversion rate 93.9% and cold gas efficiency of 64.38%. Finally, the future research directions are summarized such as synergistic hydrothermal carbonation, accurate analysis and directional regulation of phosphorus forms, hydrochar gasification mechanism, and energy, economic and environmental assessment of HTC process coupling with gasification/incineration. This paper provides scientific guidance for efficient disposal of sewage sludge with the purpose of volume reduction, energy utilization, and clean utilization.

TK6

国家自然科学基金青年项目（51706144,51606128）；上海市自然科学基金（17ZR1419500,16ZR1422900）；上海市优秀技术带头人计划（18XD1422700）；能源清洁利用国家重点实验室开放基金（ZJUCEU2017021）