猪粪源沼液振荡淋洗修复铬污染土壤效果及机制

针对铬污染土壤不易处置的难题,文章通过室内模拟实验,采用振荡淋洗的方法研究了猪粪源沼液对铬污染土壤中铬的淋洗效果,优化了固液比、淋洗时间和淋洗次数等影响土壤中总铬和六价铬洗脱效果的因子,并研究了猪粪源沼液淋洗前后土壤中铬形态分布及DOM的变化。结果表明,当环境温度为20℃,振荡速度200 r·min^-1时,沼液洗脱土壤铬的最优条件为:固液比1∶10,振荡6 h,淋洗1次。该条件下,当土壤总铬浓度为121.54 mg·kg^-1(六价铬浓度为119.9 mg·kg^-1)时,其总铬和六价铬洗脱率分别为43.27%,48.99%;当土壤总铬浓度为941.9 mg·kg^-1(六价铬浓度为856.9 mg·kg^-1)时,洗脱率达84.89%,96.32%。猪粪源沼液对水溶态、弱酸提取态和残渣态铬有较好的洗脱效果,有效削减了土壤环境风险。紫外-可见光谱和三维荧光光谱显示:淋洗后土壤DOM芳香性物质及疏水性物质减少,类腐殖酸类还原性物质增多,使得沼液对铬污染土壤有解毒效果。该研究可为铬污染土壤淋洗修复提供一定的参考价值。

Effect and Mechanism of Restoring Chromium-contaminated Soil by Oscillating Elution of Swine Manure Biogas Slurry

In view of the disposal problems of chromium contaminated soil,in this paper,through the laboratory simulation experiment,the effect of chrome-contaminated soil disposal by oscillating elution of pig manure biogas slurry was studied.The factors affecting the elution effect of total chromium and hexavalent chromium from soil,including solid-liquid ratio,elution duration and frequency,were optimized.The morphological distribution of chromium and the changes of DOM in soil before and after the elution were also investigated.The results showed that,when the ambient temperature was 20℃and the oscillation speed was 200 r·min^-1,the optimal conditions for the biogas slurry elution of soil chromium were:solid-liquid ratio 1∶10,oscillating for 6 h and eluting for 1 time.Under these conditions,when the total chromium concentration of soil was 121.54 mg·kg^-1(hexavalent chromium concentration of 119.9mg·kg^-1),the elution rates of total chromium and hexavalent chromium were 43.27%and 48.99%,respectively.When the soil total chromium concentration was 941.9 mg·kg^-1(hexavalent chromium concentration of 856.9 mg·kg^-1),the elution rate was 84.89%and 96.32%,respectively.The pig manure biogas slurry had better elution effect for water-soluble,weak acid extractable and residual chromium,which effectively reduced the risk of soil environment.UV-Vis spectra and three-dimensional fluorescence spectra showed that,after oscillating elution,the aromatic and hydrophobic substances in the soil DOM decreased,while humic acid-like reductive substances increased,which made biogas slurry have detoxification effect on chromium-contaminated soil.This study can provide some reference value for remediation of chromium contaminated soil.