【摘要】 污泥中重金属的含量和各重金属的生物有效性是污泥农业利用的重要限制因素.本研究对城市污泥进行了堆肥化处理,并采集不同阶段样品,通过顺序浸提法对样品中不同形态的重金属进行提取,分别利用原子吸收分光光度计测定Zn、Cu、Ni、Pb、Cd含量、分光光度法测定Cr和As含量.研究结果发现,与现有国际及我国污泥农用标准比较,所研究污泥中重金属含量均未超过允许的水平.污泥堆肥中Cu、Ni、Cd、Cr主要以残渣态形式存在,Cu、Ni、Pb、Cd四种重金属元素的可氧化态含量也相对较高,除Cd外,经过堆肥化处理后所有重金属的有效态含量均呈下降趋势,因此,堆肥可以促进污泥中的重金属稳定化,降低土壤的污染风险.更多还原

【Abstract】 The concentration of bio-available heavy metals in sludge is one of the major considerations for soil plant systems. Currently,land application of sludge and sludge products is determined by their total heavy metal concentrations rather than bio-available metal concentrations. Hence it is important to determine the bio-available heavy metal concentrations of sludge and sludge products for their efficient use in agricultural applications. In the present study,sludge samples composted for different durations were collected and sequentially extracted according to the BCR′s(the European Community Bureau of Reference) guidelines. The concentration of the metals Cd,Cu,Ni,Pb and Zn in the sludge extracts were determined by atomic absorption spectrometry(AAS) while the concentrations of As and Cr were determined by absorption spectrometry. The results showed that the concentrations of all the measured metals were within the maximum permitted levels prescribed by China and international legislation on use of sludge for agricultural purposes. Furthermore,a large proportion of the Cu、Ni、Cd and Cr were associated with the residual fraction,which is considered an inert form. Cu、Ni、Pb and Cd showed more affinity to the oxidizable metal fraction. Bio-availability of all the measured metals,except Cd,decreased with the increase in composting time. Therefore,we conclude that composting could stabilize the heavy metals present in the sludge and decrease the risk of soil pollution.更多还原