南昌市污水处理厂污泥中重金属的污染危害

摘要

The pollution hazards of heavy metals were investigated in sewage sludge collected from four wastewater treatment plants in Nanchang City, China, including Honggutan (HGT), Chaoyang (CY), Qingshanhu (QSH) and Xianghu (XH). Contamination/risk characteristics of heavy metals (Cu, Pb, Zn, Cd, Cr and Ni) were evaluated based on their leachable content, total content and chemical speciation. The sewage sludge from QSH contained higher total contents of heavy metals (except Pb) than those from HGT, XH and CY. The total contents of Cd and Ni were mostly beyond standard. Cu, Cr and Pb were predominantly present in potential effect and stable fractions. Zn and Ni showed higher bioavailability. Cd presented roughly uniform distribution into four fractions. The leaching contents of heavy metals almost exceeded the threshold values, especially for Zn and Ni. The potential ecological risk indexes of heavy metals in sewage sludge were 4263.34-7480.26, indicating very high risks. Cd contamination is the major concern.%对南昌市红谷滩、朝阳、青山湖和象湖4个主要污水处理厂污泥中重金属的污染危害进行探讨.依据污泥样品中重金属的总含量、化学形态和可浸出量,对污泥中Cu、Pb、Zn、Cd、Cr和Ni 6种重金属的污染特性和环境风险进行评估.研究结果表明,除了重金属Pb,青山湖污水厂污泥中重金属的总量高于其他3个污水厂污泥(红谷滩、朝阳和象湖).大部分污水厂污泥中重金属Cd和Ni总含量超过了相应的标准.重金属Cu、Cr和Pb主要以潜在影响和稳定态的形式存在,而重金属Zn和Ni则具有较高的活性,重金属Cd的化学形态分布较为均衡.重金属的可浸出量几乎都超过相应的标准值,尤其是重金属Zn和Ni.污泥中重金属的潜在生态风险指数高达4263.34~7480.26,也即,重金属的生态风险处于"非常高"的水平.另外,污泥中重金属Cd的污染占主要地位.