污泥焚烧细颗粒物中重金属赋存形态的研究

以沈阳市某污水处理厂剩余污泥为原料，采用小型流化床对污泥进行焚烧，利用布袋和荷电低压颗粒物撞击器（ELPI+）对细颗粒物进行收集，研究焚烧温度、污泥粒径、CaO的添加量对重金属赋存特性和细颗粒物微观形貌的影响，利用热力学软件FactSage7.2研究焚烧过程中重金属化学形态的变化.结果表明，随着焚烧温度的升高，残渣态变化最为明显，Cd、Cr、Cu、Pb和Zn 5种重金属的残渣态增幅均在15%以上，其中重金属Cd的变化最为明显，残渣态增幅高达29%.随着污泥粒径的增大，矿物质和焦炭颗粒的破碎程度减小，最终以矿物质和焦炭破碎为来源的一些粒径较大的细颗粒物数量增加.此外，总体上重金属的赋存形态随着粒径的增加向着稳定的趋势发展.在焚烧过程中CaO是可以作为颗粒之间良好的粘合剂，促进细颗粒物之间的成长和团聚.随着CaO的添加，细颗粒物聚并成了一个更大的球状颗粒整体.

Study on the occurrence characteristics of heavy metals in fine particulate matter during sludge incineration

The sludge samples were obtained from a wastewater treatment plant in Shenyang, Liaoning province, China. The sludge was incinerated in a lab-scale fluidized bed and the fine particulate matter was collected by the bag and electrical low-pressure impactor plus (ELPI+). Effects of incineration temperature, particle size and the addition of CaO on the occurrence characteristics of heavy metals and morphology of fine particulate matter were studied. The entire incineration process of sludge was simulated using the Equilib module of FactSage 7.2. The results showed that as the temperature increases, the changes of residual state were most obvious. The increase of residual state of Cd, Cr, Cu, Pb, and Zn was more than 15%. Among them, the change of Cd was most obvious, and the increase in residue state was as high as 29%. As the increases of particle size, the degree of crushing of minerals and coke particles decreased, and eventually the number of fine particles with larger particle sizes derived from the crushing of minerals and coke were increased and in general, the occurrence form of heavy metals was developing towards a stable trend. CaO could be used as a good binder between the particles, promoting the growth and agglomeration of fine particles during the incineration process. With the addition of CaO, the fine particles were aggregated into a larger spherical particle as a whole.