乌鲁木齐城市污泥重金属形态特征及农用可行性分析

HEAVY METALS SPECIATION OF MUNICIPAL SEWAGE SLUDGE IN URUMQI AND ITS AGRICULTURAL USE FEASIBILITY

选取乌鲁木齐市两家有代表性的污水处理厂的污泥,对其理化性质和重金属形态进行了测定,分析了污泥的农用价值和重金属的生物有效性。结果表明:乌鲁木齐两家污水厂污泥基本呈中性,含水率在70%以上,污泥呈现高有机质、高氮、高磷、低钾的特点。污泥中重金属含量均满足我国CJ/T 309—2009《城镇污水处理厂污泥处置农用泥质标准》中B级标准,但HD污水厂Zn和Cd含量、QDW污水厂Cd含量超出A级标准,不可施用于蔬菜和粮食作物。污泥中Zn和Cu主要以残渣态和有机结合态为主,其余三种形态所占比例较小,Pb和Cd以残渣态、碳酸盐结合态和铁锰氧化态为主。Zn、Cu的不可利用态所占比例在50%以上,生物可用性较低。Pb、Cd生物有效态和潜在有效态所占比例之和在50%以上,有较强的生物可利用性,在污泥农用时存在潜在风险,Cd污染问题要引起重视。

Basic quality and speciation of heavy metals in sludge from two municipal sewage plants in Urumqi were determined,agricultural use feasibility of sludge and bioavailability of the heavy metals were analyzed. The results showed that the sludge,with moisture content of 70%,presents the characteristics of high organic matter,nitrogen,phosphorus contents and low potassium contents. The contents of Zn,Cu,Cd and Pb are lower than B class limiting value of National Control Standards for Biosolids Agricultural Use( CJ / T 309—2009). However,the contents of Zn,Cd in HD plant and Cd in QDW plant were higher than the A class limiting value. Zn and Cu existed mainly in form of residues and organic. Pb and Cd existed in mainly residues,iron-manganese oxidation forms and carbonate forms. The proportions of unavailable forms of Zn and Cu were more than 50%,which was advantageous for agricultural use of the sludge. The proportions of available forms and potential available forms of Pb and Cd were more than 50%,which presented potential risk for agricultural use of the sludge.