化学方法降低城市污泥的重金属含量及其前景分析

Chemical Method and its Prospect for Heavy Metal Removal From Municipal Sludge

城市污泥含有丰富的氛、磷、河和有机质，农用前景广阔。但其中重金属含量常超标而受到限制。利用化学试剂如酸、有机物、表面活性剂等与污泥中的重金属发生作用，形成溶解性的金属离子或金属－试剂络合物，再通过淋滤．可以剔除污泥中大量的重金属，使其降低到符合农用标准。本文介绍了化学方法去除污泥事金属的原理和效果，分析了影响因素，包括重金属种类、污泥特性、操作方法、剔除时间等。并对该法的应用前景进行了讨论。

Municipal sludge use as agricultural fertilizer appears to be the most interesting alternative due to its abundant N, P K, and organic matter and from an economic perspective. However, the presence of high concentration of heavy metals represents a serious constraint to this practice. Metal removal from municipal sludge is a crux. Chemical method for metal removal has been conducted. According to the Eh-pH diagram of heavy metals, metals in sludge react with the agents including acid, organism, surface active agent and form the soluble metal ions or metal-agent chelate, and then remove a lot of heavy metals from sewage sludge by leaching. This paper introduces the principle and efficiencies of the method; and the affecting factors including specific type of heavy metals, the types and characteristics of sewage sludge, sludge solid concentration, pH value, length of acidification, etc. are analyzed. Also, the prospect of this method is reviewed.