重金属-有毒有机物复合污染土壤的过硫酸盐氧化修复模拟研究

选取电子电器废弃物拆解场地附近的重金属-有毒有机物复合污染土壤为研究对象,对其进行过硫酸钠氧化修复实验.考察了多氯联苯的去除效果及重金属(铜、镉、铅)有效态含量的变化,并对土壤基本性质的变化进行重点研究.结果表明,在本实验条件下,多氯联苯含量为10.10 mg·kg~(-1)的供试土壤经氧化修复24 h后,多氯联苯去除率高达41.6%,且对低氯代和高氯代多氯联苯都具有一定的去除效果.土壤中重金属(铜、镉、铅)的有效态含量显著提高,在一定程度上增大了其可去除性,同时也不可避免地提高了环境风险.此外,土壤经过硫酸钠氧化修复后,pH由原来的6.04降为2.56,土壤有机质含量降低了29.2%,土壤的阳离子交换量无显著变化;土壤全氮、有效磷、有效钾含量分别降低了33%、94%、24%;土壤中铁含量略有增加但不显著,然而土壤中硫含量增幅显著.建议在氧化修复后,向土壤中添加石灰和钙镁磷肥等来消除修复过程带来的不利影响.

Remediation of soils contaminated with heavy metals and toxic organic pollutants by persulfate oxidation:A lab-scale study

In the present study, the removal efficiency of polychlorinated biphenyls (PCBs) and the bioavailable contents of heavy metals (Cu, Cd and Pb) were studied in the soil samples from electronic waste recycling area by using persulfate oxidation in the lab scale. The effects on soil quality were also investigated by the treatment of persulfate oxidation. In this experiment, the soil with PCBs concentration of 10.10 mg·kg^-1 was treated for 24 h. It was shown that the removal rate of PCBs was 41.6% and the treatment had good removal efficiencies for low-chlorinated and high-chlorinated PCBs. In addition, the bioavailable fractions of heavy metals (Cu, Cd, and Pb) in soil was improved. This treatment increased its removability to a certain degree, but the environmental risks inevitably improved. After the experiment, soil pH decreased from 6.04 to 2.56 and soil organic matter content decreased by 29.2%, while the cation exchange capacity didn''t changed significantly. The total nitrogen content and available potassium decreased by 33% and 24%, respectively, while the Olsen-P content decreased by 94%. There was slight increase of iron contents while significant increase of sulfur contents.Adding lime and fused calcium-magnesium phosphate was recommended to eliminate the adverse effects in further study and the practical remediation.