陕西省典型城市污泥养分与重金属含量调查

Major nutrients and heavy metals of municipal sludge in Shaanxi Province

分别采集陕西省22家典型城市污水处理厂丰水期和枯水期的污泥样品,研究其总氮、总磷、总钾、有机物以及Pb、Cd、Cu、Zn、Ni、Cr、Hg、As等8种重金属含量与其形态分布特征。结果表明,陕西省主要城市污泥pH为6.34~8.54,污泥中有机物、总氮、总磷高于传统农家肥,但总钾含量较低。污泥中有机物、总氮、总磷和总钾含量均受到水期的显著影响(P<0.05)。8种重金属含量表现为Zn>Cu>Cr>Pb>Ni>As>Hg>Cd,其中Zn、Cr、Hg含量受到水期的显著影响(P<0.001)。形态分析表明,Cu、Ni、Cr、Cd主要以有机物结合态和残渣态存在,Zn主要以铁锰氧化物结合态、有机物结合态和残渣态存在,Pb主要以残渣态存在。总体而言,陕西省城市污泥具有较高的土地利用价值,适合施用于园地、牧草地、不种植食用农作物的耕地以及中碱性土壤土质改良,但需特别注意Pb、Cd、Hg、As含量的控制。

Sludge samples were collected from 22 urban sewage treatment plants in Shaanxi Province in raining seasons and dry seasons and the content characteristics of TN,TP,TK and organic matter(OM),as well as the content and speciation of heavy metals(Pb,Cd,Cu,Zn,Ni,Cr,Hg,As)were then determined.Results showed that pH of these municipal sludge ranged within 6.34-8.54.The OM,TN and TP contents were higher than that of common farmyard manure but the TK content was relatively lower.OM,TN,TP and TK contents were very significantly affected by the water period(P<0.05).The contents sequence of 8 kinds of heavy metals were Zn>Cu>Cr>Pb>Ni>As>Hg>Cd.Zn,Cr and Hg were very significantly affected by the water period(P<0.001).Cu,Ni,Cr and Cd existed mainly in residual form and organic bound form,Zn existed mainly in iron-manganese oxygen union form,organic bound form and residual form,and Pb existed mainly in residual form.The urban sludge in Shaanxi Province had a high agricultural value.The sludge was suitable for application in forest land,pasture grassland and cultivated land without growing edible crops and land modification for medium alkaline soil.Meanwhile,special attention should be paid to Pb,Cd,Hg,As contents control in the sludge.