矿物基胶凝材料对酸性重金属污染土壤原位修复

In-situ remediation of acidic heavy metal contaminated soil using mineral-based binding materials

针对向山3#塘土壤Cu和Mn重金属超标和pH低等问题,以矿物基复合胶凝材料作为胶结材料,制备了一系列原位淤泥固化试样,研究固化剂掺量对淤泥固化试样无侧限抗压强度、抗渗透性能、pH值、重金属浸出的影响,并对污染土壤原位修复的机制进行初步探讨。结果表明,当固化剂掺量为7.5wt%时,淤泥固化试样(28 d)的无侧限抗压强度为1.03 MPa,使得3#塘淤泥质土壤具有一定的强度,可进行资源化利用。试样渗透系数为1.436×10^(-5)cm/s,其浸出液中Cu和Mn离子含量分别为0.058和0.021 mg/L,浸出浓度远低于标准限值,离子的固定率分别为96.13%和99.90%。pH增大和水化产物C-S-H、AFt的生成可以有效地改善土壤中Cu和Mn离子的稳定效果。

To resolve the problems of excess levels of Cu and Mn heavy metals and low pH in the soil of Xiangshan No.3 pond,a series of sludge solidification samples were prepared using mineral-based composite cementitious materials as binding materials.The effects of curing agent content on the unconfined compressive strength,impermeability,pH,and heavy metal leaching of the sludge solidification samples were studied,and the mechanism of in-situ remediation of contaminated soil was preliminarily discussed.The experimental results showed when the content of curing agent was 7.5wt%,the unconfined compressive strength of sludge solidification sample(28 d)was 1.03 MPa.which gave the sludge soil in No.3 pond a certain strength,thus enabling the utilization of farmland resources.Meanwhile,the permeability coefficient of the sample was 1.436×10^(-5)cm/s.The concentrations of Cu and Mn ions in its leachate were 0.058 and 0.021 mg/L,respectively,which were much lower than the standard limit,and the fixation rates were 96.13%and 99.90%,respectively.The increase in pH and the generation of hydration products C-S-H and AFt can effectively improve the stability of Cu and Mn ions in soil.