城市污泥中重金属有效态分布特征研究

Study on Chemical Forms Distribution Characteristics of Heavy Metals in Municipal Sewage Sludge

以沈阳市北部污水处理厂剩余活性污泥为研究对象,对污泥中重金属Cd,Pb,Cu,Zn的含量及其形态分布特性进行分析。结果表明：污泥中4种重金属的含量基本符合国家相关控制标准（GB 18918-2002和CJ248-2007）。采用8种提取剂（0.05 mol/L EDTA,0.01 mol/L CaCl2,0.01 mol/LCa2（NO3）2,0.1 mol/L NaNO3,1 mol/L NH4OAC,0.43 mol/LHAC,0.05mol/L NaHCO3和0.05 mol/L Tris-HCl）分别对污泥中重金属的螯合态,中性交换态,酸溶态,碱溶态和蛋白质结合态进行分离分析。结果表明：4种重金属螯合态存在的比例较大,分别占各重金属总量的5.9%~27.2%,其次为酸溶态和中性交换态,而以碱溶态和蛋白质结合态形式存在的比例较少,除Cd外均低于1%。污泥中Cd和Pb具有较高的活性,而Cu,Zn在碱性污泥中主要以稳定态存在。

The contents and form distribution characteristics of Cd, Pb, Cu and Zn in sludge were analyzed, taking the surplus sludge of the North Municipal Sewage Treatment Plant in Shenyang as study object. The results showed that the contents of 4 heavy metals in sludge were in accordance with the relevant national standard （GB18918-2002 and CJ248-2007）. The chelated forms, neutral exchange forms, acid-soluble forms, alkali-soluble forms and protein- binding forms of heavy metals in sludge were separated and analyzed using eight kinds of extractants （ 0.05 mol/L EDTA, 0.01 mol/L CaC12, 0.01 mol/L Ca（NO3）2, 0.1 mol/L NaNO3, 1 mol/L NI-I4OAC, 0.43 mol/L HAC, 0.05 mol/L NaHCO3 and 0.05 mol/L Tris-HC1）. The results showed that the higher proportion of chelated forms existed at the level of 5.9%~27.2% in sludge, followed by the acid-soluble forms and neutral exchange forms. The lower ratios of alkali-soluble forms and protein- binding forms were less than 1% except Cd. The existence forms of Cd and Pb had high activities in sludge, but the stable forms of Cu and Zn existed mainly in the alkaline sludge.