焦化场地PAHs污染土壤的电动-化学氧化联合修复

焦化场地土壤多环芳烃(PAHs)污染严重,目前的修复技术都存在不同程度的弊端。通过研究化学氧化、电动及其联合技术对焦化场地高浓度多环芳烃污染土壤的修复效果,比较了两种技术组合方式对修复效果的影响。结果表明,单一技术及联合技术对焦化场地PAHs均有一定的去除效果。在单一技术处理中,电动处理、芬顿和活化过硫酸钠对多环芳烃的去除率分别为24.86%、10.27%和22.19%;在联合技术处理中,活化过硫酸钠-电动组合、电动-活化过硫酸钠组合、芬顿-电动组合和电动-芬顿组合对多环芳烃的去除率分别为49.65%、41.73%、36.72%和31.39%。电动-化学氧化联合技术对PAHs的去除效果较单一技术提高了6.53%~27.46%。两种技术的组合方式及氧化剂类型均对联合处理效果产生影响,化学氧化-电动处理的多环芳烃去除率较电动-化学氧化处理高5.33%~7.92%,其差异主要由化学氧化去除率差异所引起;应用活化过硫酸钠试剂的组合对多环芳烃的去除率高出应用芬顿试剂的组合12.93%~10.34%。经联合处理后,污染物的残留量及毒性当量浓度均有不同程度降低,说明电动-化学氧化联合技术是一种有效的预处理方法。

Remediation of PAHs Contaminated Soil at Coking Site by Integrated Electrokinetics and Chemical Oxidation

Soils at coking sites have been heavily contaminated with PAHs. Currently there is lack of effective remediation techniques for PAHs-contaminated soils. In this study, the efficiencies of chemical oxidation and electrokinetics and their integration for remediating PAHs heavily contaminated soils from coking sites were evaluated in a laboratory-scale experiment. Removal rates of PAHs were 24.86%, 10.27% and 22.19%, respectively, in treatments of electrokinetics, Fenton and activated persulfate. However, higher removal rates of PAHs were achieved for activated persulfate-electrokinetics, electrokinetics-activated persulfate, Fenton-electrokinetics and electrokinetics-Fenton, which were 49.65%, 41.73%, 36.72% and 31.39%, respectively. Integrating electrokinetics and chemical oxidation further enhanced the removal rate of PAHs by 6.53%~27.46% compared to electrokinetics or chemical oxidation alone. The sequence of applying electrokinetics and chemical oxidants and oxidant types impacted on the PAHs removal efficiency. Chemical oxidation- electrokinetics removed 5.33%~7.92% more PAHs than electrokinetics-chemical oxidation did. Applying activated persulfate increased PAHs removal by 12.93% ~10.34% compared to using Fenton. These results show that integration of electrokinetics and chemical oxidation could be a promising pre-treatment technique to remove the PAHs in highly contaminated soils efficiently and to alleviate the residual toxicity.