含重金属污泥制砖毒性的浸出

污泥中的重金属是影响污泥处置利用的重要因素,污泥制砖可以有效固结重金属。采用污水厂污泥与页岩按一定配比混合制备烧结砖,通过毒性浸出实验,研究烧结砖对重金属的固化程度以及重金属浸出稳定性,从而评定烧结制砖的安全性。结果表明,在浸出液为中性和酸性条件下,Cu、Cr、As和Pb的浸出浓度基本保持稳定,浸出时间的影响不大,而Zn的初始浸出浓度相对较大,最终逐渐降低;碱性条件下,Cr、Cu和Pb的浸出浓度随时间变化不大,而Zn和As的浸出浓度则在浸提时间内无明显变化规律;但不同pH浸出液下的重金属浸出浓度均远低于国家限值,污泥制砖重金属固化效果好,安全可靠。

Toxicity leaching of brick making from sludge containing heavy metals

The problems of heavy metal in sludge from sewage treatment plants has attracted much attentions.One proposal to reduce the harm of heavy metals was to make brick which can solidify them during the sintering process.The sewage sludge was mixed with shale according to a certain proportion to prepare brick,then the solidified effect of heavy metals as well as the toxicity extraction were studied to examine the safety of sintered brick.The results showed that the leaching concentrations of Cr,Cu,As,Pb hardly changed with time under neutral and acidic conditions,while that of Zn was relatively high firstly then reduced.Moreover,under alkaline conditions,the leaching concentrations of Cr,Cu,Pb stayed stable,whereas that of Zn,As changed irregularly.Overall,the performance of stabilization/solidification for Cr,Cu,Zn,As,Pb is well-behaved,and the leachate toxicity of sludge bricks is lower than that of the national standard.