淋洗和淋滤下鼠李糖脂对酸性镉污染土壤的修复效果试验研究

Rhamnolipid Treatment of the Cadmium Contaminated Acid Soil by Elution and Leaching Experiments

为研究鼠李糖脂对酸性镉污染土壤的治理效果,同时采用淋洗和淋滤试验,对比研究了两种处理方法对酸性镉污染土壤的修复效果。淋洗试验结果表明:鼠李糖脂能有效解吸人工镉污染土壤中的镉,且在淋洗时间为0~24h内对土壤中镉的解吸速率最快,在此阶段高浓度鼠李糖脂溶液对土壤中镉的解吸效果低于低浓度鼠李糖脂溶液;经过68h淋洗后,低浓度鼠李糖脂溶液对人工镉污染土壤中镉的解吸量开始衰减,而高浓度鼠李糖脂溶液对人工镉污染土壤中镉的解吸量则持续增加,此阶段高浓度鼠李糖脂溶液对土壤中镉的解吸效果优于低浓度鼠李糖脂溶液,且对土壤中镉的最高解吸量达到144.45mg/kg,其解吸过程符合准二级吸附动力学方程。淋滤试验结果表明:经过168h淋滤后,天然镉污染土壤中镉的去除率达到62.84%,且淋滤后土壤中镉的含量低于《土壤环境质量--农用地土壤污染风险管控标准(试行)》(GB15618-2018)中土壤镉污染的风险筛选值。在治理酸性镉污染土壤时,淋滤的处理效果优于淋洗,该研究结果对治理酸性镉污染土壤具有一定的参考价值。

In order to study the rhamnolipid treatment of cadmium contaminated acid soil,this research conducts elution and leaching experiments,and compares the treatment effect.The elution experiment results show that rhamnolipid can effectively desorption soil cadmium with the fastest leaching rate occurring in 0~24 hours,and the lower rhamnolipid solution concentration has a better treatment effect than that of the higher rhamnolipid solution concentration during this term.After 68 hours leaching,the desorption amount of the low rhamnolipid concentration treatment begins to attenuate while that of the high rhamnolipid concentration treatment increases continuously.In this term,the lower rhamnolipid concentration has a worse treatment effect than that of the higher rhamnolipid concentration with the maximum desorption amount of 144.45 mg/kg.Cadmium desorbed from the acid soil under the effect of rhamnolipid can be described by the Quasi-two-order kinetic equation.The leaching experiment demonstrates that the 20 g/L rhamnolipid solution with 168 hours leaching can result in a 62.84% removal rate for the cadmium contaminated acid soil,which reaches the safe value.For cadmium contaminated acid soil,the leaching experiment has a better treatment effect than that of the elution experiment.