城市污泥中重金属形态及资源化可行性分析

以南方某市6个污水处理厂为例,分析污泥中重金属Cu,Zn,Ni,Pb,Cd,Cr的质量比及其形态分布特征,分析污泥农用的最大施用量和制砖的最大添加量.结果表明:污泥中的Pb,Ni,Cd有效态比例较高,Zn,Cr主要以不可利用态存在,Cu主要以潜在有效态和不可利用态存在.污泥农用的静态环境容量分析结果显示:不同来源污泥的最大施用量有显著差异,可将Cd作为主要监控污染元素,同时作为控制城市污水污泥农用过程中最高施用量的计算参考指标,以保证土壤环境安全.通过制砖污泥添加比例的计算,选取Cu作为E污水厂污泥制砖过程的限制性指标,其余5个污水处理厂的限制性指标为Cr.

Form of Heavy Metals in Sewage Sludge and Resource Feasibility in Southern City

The content and form distribution of heavy metals(Cu, Zn, Ni, Pb, Cd, Cr)from sewage sludge in six wastewater treatment plants in a southern city of China were investigated. The maximum amount of sewage sludge which could be applied to agricultural soil and brick was also calculated. Results revealed that Zn and Cr existed mainly in unavailable form, and Cu was in a state of potentially effective and unavailable fraction. The effective proportions of Pb, Ni and Cd were larger than other metals. As calculated by the static environmental capacity of latosolic red solid of the city, the main detected harmful heavy metal was Cd in the course of agriculture utilization of sludge. The maximum application amount of sludge from various sources were significantly different. Therefore, we suggested that the content of Cd in sewage sludge could be used as a reference index, which was used for calculating the maximal application rate in the control of application rate of sludge for agricultural land, and for the protection of solid environment. As calculated by the addition ratio of the sewage sludge in the brick, the main control index was Cu in the E wastewater treatment plant, meanwhile Cr was selected as the dangerous heavy metal in the other five wastewater treatment plants.