我国城市污水处理厂污泥中重金属分布特征及变化规律

对由中国知网数据库和维普中文科技期刊全文数据库报道的近30年来我国城市污水处理厂污泥中重金属分布特征和年代变化规律进行了分析. 结果表明:近30年来城市污水处理厂污泥中w(Cd)、w(Pb)、w(Cr)、w(As)、w(Hg)、w(Cu)、w(Ni)、w(Zn)平均值或中位值均符合GB 18918─2002《城镇污水处理厂污染物排放标准》中污泥农用时污染物控制标准限值,但数据离散且呈偏态分布. 依据GB 18918─2002,1980─1989年我国城市污水处理厂污泥中重金属质量分数75%分位值中有w(Cd)、w(Cu)、w(Ni)、w(Zn)超标,90%分位值中有w(Cd)、w(Pb)、w(Hg)、w(Cu)、w(Zn)、w(Ni)超标；1990─1999年城市污水处理厂污泥中重金属质量分数75%分位值中w(Ni)超标,90%分位值中除w(As)外其他重金属均超标；2000─2010年城市污水处理厂污泥中重金属质量分数75%分位值中w(Ni)超标,90%分位值中w(Cd)、w(Cr)、w(Hg)、w(Cu)、w(Zn)、w(Ni)超标. 从年代变化看,我国城市污水处理厂污泥中w(Cd)、w(Cu)随年代逐渐下降,但w(Hg)、w(As)、w(Cr)、w(Zn)、w(Ni)、w(Pb)呈波动趋势. 近10年数据表明,我国城市污水处理厂污泥中w(Ni)、w(Cd)、w(Hg)超标倍数最高,在进行污泥处置时需要优先关注. 

Characteristics and Changes of Heavy Metals in Sewage Sludge of China

Heavy metal is one of the major limiting factors for applications of the sewage sludge to the agricultural land. In this study, we collected the published data concerning the concentrations of heavy metals in the sewage sludge all over China from literature databases, then analyzed all the data and summarized the concentration characteristics of heavy metals and their historical changes in the past 30years. The results showed that the median concentrations of Cd, Pb, Cr, As, Hg, Cu, Ni and Zn in the sewage sludge were below the permissible limits regulated by the “Discharge standard of pollutants for municipal wastewater treatment plant” of China (GB 18918-2002). In 1980-1989, about 25% of Cd, Cu, Ni and Zn concentrations and 10% of Cd, Pb, Hg, Cu, Zn and Ni concentrations in the sewage sludge were higher than the standard; In 1990-1999, about 25% of Ni concentrations in the sewage sludge was higher than the standard, while 10% of Cd, Pb, Cr, Hg, Cu, Ni and Zn concentrations in sewage sludge were over than the standard; In 2000-2010, about 25% of Ni concentration and 10% of Cd, Cr, Hg, Cu, Zn and Ni concentrations in the sewage sludge was higher than the standard. In the last three decades, concentrations of Cd and Cu in the sewage sludge decreased gradually with the time progressing. According to the databases in the last decade, Ni,Cd and Hg should be taken as primary considerations in the pollution source control of heavy metals in the sewage sludge.