甘蔗渣修复铬污染土壤的效果

通过室内模拟培养实验，探讨了甘蔗渣修复铬污染土壤的效果、土壤中六价铬初始浓度和甘蔗渣添加量对六价铬还原反应一级动力学的影响、微生物对甘蔗渣修复铬污染土壤效果的影响及甘蔗渣修复铬污染土壤的机理。结果表明，甘蔗渣能有效地降低污染土壤中铬的浸出毒性和去除土壤中的六价铬。当甘蔗渣的添加量为5%，六价铬浓度低于1 740 mg·kg-1时，培养70 d内，土壤样品的浸出液中六价铬未检出，培养90 d内，土壤中六价铬的去除率趋近100%。土壤中六价铬的还原反应速率随六价铬初始浓度的增加而减小，随甘蔗渣添加量的增加而增大。同时，灭菌和未灭菌条件下，甘蔗渣对铬污染土壤的修复效果差异性不显著。甘蔗渣修复铬污染土壤的机理可能是甘蔗渣中的蔗糖和纤维素先降解生成葡萄糖和果糖，接着葡萄糖和果糖将土壤中的六价铬还原成三价铬。

Effectiveness of sugarcane bagasse for decreasing chromium in soils

This research was designed to study the effectiveness and mechanism of the use of sugarcane bagasse (SB) for decreasing Cr(Ⅵ) in Cr(Ⅵ)-contaminated soils. Specifically, the effects of the initial Cr(Ⅵ) concentration in soils, SB concentrations, and presence or absence of microorganisms on the effectiveness of SB at remediating Cr(Ⅵ)-contaminated soils were evaluated by chamber simulation experiments. The results indicate that SB can decrease the extract toxicity of chromium and remove Cr(Ⅵ) from soils. When the SB concentration was 5% and the initial Cr(Ⅵ) concentration was below 1740 mg·kg-1, Cr(Ⅵ) was not detected in the leached liquids over a period of 70 days and the removal rate of Cr(Ⅵ) was close to 100% over a period of 90 days. The reduction rate of Cr(Ⅵ) in soils increased with decreases in the initial Cr(Ⅵ) concentration and increases in the initial SB concentration. Additionally, the effectiveness of SB for decreasing Cr(Ⅵ) in sterile and nonsterile soils did not show any significant differences. The mechanism by which SB decreases Cr(Ⅵ) in Cr(Ⅵ)-contaminated soils probably involves the reduction of SB by glucose and fructose transformed from SB.