矿渣基改性剂对城市污泥重金属稳定化

Stabilization of Heavy Metals in Municipal Sludge Using a Slag-Based Modifying Agent

以城市生活污泥为研究对象,采用矿渣基改性剂在不同投加量和养护时间条件下对其改性,并通过重金属的稳定效率及形态变化分析和评价污泥中Cr、Cu、Zn、Pb、As和Cd等重金属的固化效果.结果表明:随养护时间或投加量的增加,重金属稳定效率不断提升,在养护14 d后,改性剂的投加量为50%时达到最大,其中Cu最高为69.62%,Cr最低为48.68%,且皆在投加量为5%~20%时增长最快.通过对投加量、养护时间和稳定效率回归分析,发现Cu的拟合相关系数最高为0.97,改性剂的掺量与养护时间两个影响因素相互作用极强,对重金属稳定效率的增加均有显著的影响.此外,污泥改性后Pb和As以残渣态为主;Cu和Cr以可氧化态和残渣态为主;Zn和Cd以可还原态和可提取态的形式为主.随养护时间或投加量增加,各重金属的残渣态有7%~86%的增加,这表明矿渣基改性剂可有效固化污泥中重金属,使污泥等固体废物再利用.

Taking urban domestic sludge as the research object,a slag-based modifying agent was used to modify sludge under different dosages and curing times,and the solidification effect of six heavy metals in the sludge,namely Zn,Cr,Cu,Pb,As,and Cd,were evaluated by analyzing stability efficiency and morphological changes. The results showed that the stability efficiency improved as curing time and dosage increased,reaching the maximum when the curing time was 14 d and the dosage was 50%. Under these conditions,Cu reached the maximum of 69. 62%,and the most rapid growth was observed when dosages were 5%-20%. Through the regression analysis of adding amount,maintenance time and stability efficiency,it was found that the fitting correlation coefficient Cu was the highest 0. 97,with a strong degree of fitting and a strong interaction between adding amount and maintenance time,which had a significant influence on the stability efficiency. In addition,Pb and As were the residual state,Cu and Cr were oxidizable state and residue state,Zn and Cd were reducible and extractable state as the main forms in the sludge after modifying,respectively. With the increase of curing time or dosage,the residual state of each heavy metal increased by 7%-86%. The results showed that the slag-based modifying agent could effectively solidify heavy metals in sludge and reused solid wastes such as sludge.