污泥干化使重金属形态变向稳定的原因分析

在模拟条件下对不同类型污泥进行连续干化,研究了不同干化温度下污泥重金属存在形态的分布特征.同时,通过测定污泥含水率、密度、温度和电导率等物性参数,分析了污泥干化过程重金属形态向稳定态转变的原因.结果表明,污泥中重金属存在形态的分布特征因污泥类型及来源不同而具有明显的差异;污泥干化过程可以使酸溶态、可还原态和可氧化态重金属向残渣态重金属转变;干化过程中污泥物性的改变和部分有机质和硫化物的分解是引起污泥重金属存在形态发生变化的主要原因.研究结果对于深入了解污泥中重金属的环境地球化学行为具有重要的理论意义,同时还可为污泥无害化、减量化和资源化的最终处理提供科学依据.

Mechanisms of heavy metal stabilization during sludge drying

During a number of drying experiments of different types of sludge under different drying temperatures, the forms of heavy metals in sludge as well as other properties of the sludge such as moisture content, density, temperature and electrical conductivity were monitored and analyzed. The results show that the original distributions of heavy metals among various forms in the tested sewage sludge are quite different, depending on sludge types and sources. However, the drying process tends to stabilize the heavy metals by transforming the acid-soluble, the reducible and the oxidizable heavy metals into the residue heavy metals. Such transformation and stabilization are mainly caused by the changes of sludge properties associated with decomposition of organic matter and sulfide. The findings are not only improved our understanding of the environmental geochemical behavior of heavy metals in sewage sludge, but also provide a scientific foundation for environment-friendly disposal of sewage sludge.