蚯蚓活动对城市生活污泥重金属的影响

Effects of Earthworm Activity on Heavy Metals in Sewage Sludge

采用塑料温棚内垄式堆积污泥培养蚯蚓方式,研究了蚯蚓处理对污泥重金属的影响。结果表明,污泥经蚯蚓处理后,理化性质发生了显著的变化,污泥的pH值、有机质、总氮和总磷都有不同程度的降低;蚯蚓能吸收富集污泥中的重金属,其中对重金属Cd有较强的富集能力;蚯蚓处理使污泥中重金属含量均出现不同程度的下降,重金属Cr、Zn、Pb、Cd、Cu、Ni分别减少27.98%、31.46%、32.81%、13.85%、23.86%和22.92%。利用盆栽试验,研究了污泥施用于土壤后生菜体内重金属积累的情况,结果表明,生菜体内重金属Zn、Cu、Pb和Ni的含量为污泥处理高于蚓粪处理;Cr和Cd则分别为差异不显著和略有降低。

This study was designed to evaluate the effects of earthworm activity on heavy metals in sewage sludge. Results showed the parameters such as pH,water content,organic carbon,Kjeldahl nitrogen and total phosphorous were lower in case of treated sewage sludge than primary sewage sludge. Earthworms could accumulate heavy metals of sewage sludge. The bio-concentration factor of Cd in earthworm was higher than other heavy metals. The reduction in metal content（as compared to initial level） was in the order：32.81%（Pb）31.46%（Zn）27.98%（Cr）23.86%（Cu）22.92%（Ni）13.85%（Cd）. It was clear that heavy metal loss was caused by the presence of earthworms. A pot-culture experiment was conducted to study the concentrations of heavy metals to lettuce,grown in soil amended with sewage sludge with and without earthworm treatment. Zn,Cu,Pb and Ni concentrations in lettuce were higher in case of primary sewage sludge than treated sewage sludge,while Cr had no change and Cd was found to decrease slightly.