城市污泥处理过程中重金属迁移转化特性研究进展

城市污水处理厂污泥产量大、成分复杂，处置不当会对环境产生二次污染。污泥中的重金属在污泥处理处置过程中不可降解，仅发生固液相迁移和化学形态的转化，导致其在环境中积累和迁移，最终进入食物链危害人体健康。重金属的危害不仅与其种类、含量等相关，化学赋存形态也是其生物有效性、迁移性和生态毒性等的关键影响因素。针对城市污泥无害化、稳定化、减量化、资源化过程常用的处理方法，包括物理法（热水解、超声波、微波）和化学法（热解、酸处理、氧化、电化学）等，重点论述了各种处理方法对污泥中重金属相间迁移及化学形态转化的影响，分析重金属迁移转化的原因，并对该过程相关机理进行总结，在此基础上提出城市污泥重金属风险控制的建议，包括污泥中重金属总量削减和稳定化，以及控制污水中重金属含量。

Research progress on the characteristics of heavy metal transfer and transformation in municipal sludge treatment

A large amount of sewage sludge is produced during the municipal wastewater treatment process with complex composition, and improper disposal would cause secondary pollution to the environment. Heavy metals in the sludge cannot be degraded in the sludge treatment and disposal process with only solid-liquid phase migration and chemical speciation transformation, and they will accumulate and migrate in the environment and finally enter the food chain and endanger human health. Not only the environmental risk of heavy metals is determined by their types and contents, but the chemical speciation distributions of the heavy metals are also the key factors affecting their bioavailability, migratability and ecological toxicity. Focusing on common treatment methods used in the harmlessness, stabilization, reduction and recycling of municipal sludge, including physical methods (thermal hydrolysis, ultrasonic, microwave) and chemical methods (pyrolysis, acid treatment, oxidation, electrochemistry), the impacts of these methods on interphase migration and chemical speciation transformation of heavy metals were described briefly. The reasons for the migration and transformation of the heavy metals were analyzed, and the relevant mechanisms were summarized and discussed. On this basis, recommendations were put forward for risk control of heavy metals in the sewage sludge, including total amount reduction and stabilization of heavy metals in the sewage sludge, as well as the control of heavy metal content in the wastewater.