硅肥和磷矿粉复配对垃圾填埋场重金属污染土壤的修复

Remediating heavy metal contaminated soil in landfills with a compound of silicon fertilizer and phosphate ore powder

以四川省盐亭县云溪镇垃圾填埋场的紫色土为研究对象,将不同质量分数的硅肥(Si1:0.5%,Si2:1.0%)和磷矿粉(P1:0.2%,P2:0.4%,P3:1.0%)复配添加到土壤中培养90 d,研究钝化培养前后重金属Cd、Cu、Pb、Zn有效态含量的变化,并利用风险评价系数(risk assessment code,RAC)评价土壤修复效果。结果显示,高硅处理(Si2:1.0%)相比于低硅处理(Si1:0.5%)能显著降低重金属有效性,其中,Si2P3处理对Cd、Cu、Pb、Zn的钝化率最高,分别为30.79%、27.27%、27.13%、36.88%;Si2P1和Si2P2处理之间没有显著差异,而Si2P1处理可以显著降低重金属浸出毒性量和RAC。研究表明,复配钝化剂主要通过提高土壤pH和EC值,增强O-Si-O、Si-O-Si、H_(2)PO_(4)^(-)、PO4^(3-)等官能团的络合沉淀作用促使重金属由高活性的弱酸提取态、可还原态向低活性的可氧化态、残渣态转化。综合来看,Si2P1处理钝化剂施用量更低,更适合用于垃圾填埋场重金属污染土壤的修复。

The purplish soil from the landfill in Yunxi Town,Yanting County,Sichuan Province was used to study the changes in the content of available heavy metals including Cd,Cu,Pb,Zn before and after passivation culture.Different mass ratios of silicon fertilizer(Si1:0.5%,Si2:1.0%)and phosphate ore powder(P1:0.2%,P2:0.4%,P3:1.0%)were mixed as compound and added to the soil.The passivation was cultured for 90 days.The effectiveness of soil remediation was evaluated with risk assessment code(RAC).The results showed that the effectiveness of heavy metals under the treatment with high silicon(Si2:1.0%)was significantly reduced compared with that under the treatment with low silicon(Si1:0.5%).Among them,Si2P3 treatment had the highest passivation rate for Cd,Cu,Pb,and Zn,which was 30.79%,27.27%,27.13%,and 36.88%,respectively.There was no significant difference between Si2P1 treatment and Si2P2 treatment.Si2P1 treatment significantly reduced the toxicity of heavy metal leaching and the RAC risk assessment code of heavy metals.It is indicated that the passivator for compound mainly enhanced the complex-precipitation of functional groups(O-Si-O,Si-O-Si,H_(2)PO_(4)^(-),PO4^(3-),etc.)by increasing the pH and EC value in soil,promoting the transformation of heavy metals from highly active weak acid extraction and reducible states to low actively oxidizable and residual states.Overall,the application amount of Si2P1 passivator is lower,making it more suitable for the remediation of heavy metal contaminated soil in landfills.