某城市污水A2/O处理过程中重金属去除率分析

以A2/O法污水处理厂的城市污水实际处理过程中重金属的变化为研究对象,分析了六种重金属(Cu、Zn、Pb、Cd、Cr、Hg)在处理过程中的去除率。研究结果表明:A2/O法对城市污水中重金属总的去除率是比较高的,都在78%以上,但在处理过程中受其存在状态、污水pH和本身的沉降、吸附、交换性质的影响,各种金属去除率并不完全相同的,总的去除率的大小顺序是:Zn>Hg>Cu>Cr>Cd>Pb。一级处理由于在同一pH、Eh下,不同的重金属以颗粒态和胶体存在的量不同,由高到低的顺序是:Cr>Cu>Zn>Hg>Pb>Cd。不同的金属离子与其配位基团的配位能力、离子交换能力和吸附能力不同,生化处理去除效果不同。从设计处理能力和重金属监测结果来看:一级处理水的主要控制项目多数达不到《城镇污水处理厂污染物排放标准》GB18918-2002的要求,应加大二级处理和深度处理能力,减轻陆源污染物对海域的污染负荷,提高中水的回用率。

Analysis of Heavy Metals Removal through A2/O Process of Municipal Wastewater Treatment in Yantai City

This paper deals with heavy metals removal through the secondary treatment process in a municipal wastewater treatment plant based on A2/O in Yantai. Effluents from the primary sedimentation tank and secondary sedimentation tank were sampled and analyzed respectively. Result indicates that,in general,as high as 78% plus of heavy metals,with the order of Zn>Hg>Cu>Cr>Cd>Pb,is removed through the secondary treatment depending on the pH,temperature,age of sludge,heavy metal concentration and the characteristics of adsorption and ion exchange between the specific heavy metal and activated sludge. Mechanism governing the removal of heavy metals by activated sludge is discussed as well.