城市污水处理厂污泥重金属污染状况及特征

研究了我国16家城市污水处理厂污泥中重金属(Cu，Cr，Pb，As和Cd)污染状况及特征，并探讨了可行的污泥处置方法. 结果显示:w(Cu)，w(Cr)，w(Pb)，w(As)和w(Cd)(干基)分别为14.48～239.93，7.86～200.00，6.10～121.00，3.15～11.70和0.31～6.16 mg/kg；不同种类的重金属在污泥中的质量分数也不同，w(Cu)和w(Cr)高于w(Pb)，w(As)和w(Cd)；污泥中重金属质量分数还随污水处理厂的不同而变化，这与污水来源和污水处理工艺有关. 分析表明，除7号污水处理厂污泥中w(Cd)超出我国农用泥质(CJ/T309—2009)A级污泥、园林绿化用泥质(GB/T23486—2009)和土地改良用泥质(CJ/T291—2008)中酸性土壤(pH<6.5)施用标准外，其他污水处理厂的污泥重金属质量分数均低于我国农用泥质(CJ/T309—2009)A级污泥标准以及美国、德国和欧盟农用污泥标准的重金属控制限值. 达标的污泥可将混合填埋、农用、园林绿化、土地改良、制砖和水泥熟料生产作为污泥处置备选方案. 

Pollution Status and Characteristics of Heavy Metals in Sewage Sludge from Municipal Wastewater Treatment Plants

The pollution status and characteristics of heavy metals including Cu, Cr, Pb, As and Cd in sewage sludge samples from 16 municipal wastewater treatment plants in China were investigated, and the feasible disposal methods of sewage sludge were discussed. The results showed that the contents of Cu, Cr, Pb, As and Cd ranged from 14.48-239.93, 7.86-200.00, 6.10-121.00, 3.15-11.70 and 0.31-6.16 mg/kg (dry basis), respectively. It was found that the contents of the heavy metals varied with their species. The contents of Cu and Cr were always higher than those of Pb, As and Cd. For different wastewater treatment plants, the contents of the same heavy metals turned out to be different, which may be the result of different wastewater resources and treatment processes in the plants. The contents of the heavy metals in all the sludge samples except one were below the permitted limits of sludge quality standards of China (CJ/T309-2009), and the sludge quality standards for agricultural use of America, Germany and the European Union. The one exception was the sludge sample of the No.7 wastewater treatment plant, for which Cr content exceeded the permitted limits of the A-class sludge quality standard of China for agricultural use (CJ/T309-2009), the acidic soil (pH<6.5) of the sludge quality standards for afforestation in gardens or forests (GB/T23486-2009). and for land improvement (CJ/T291-2008). It was deduced that all the sewage sludge up to the standards might be utilized not only for co-landfilling, but also for agriculture, afforestation in gardens or forests, land improvement, brick making and cement clinker production.