IN SITU GAS THERMAL REMEDIATION OF A RELOCATED COKE PLANT: A PILOT STUDY

摘要

In situ gas thermal remediation (GTR) was applied in the pilot study for the first time for remediation of polycyclic aromatic hydrocarbons (PAHs) contaminated soil of a relocated coke plant in Beijing, China. The pilot site squared by 10 m x 10 m was heated by 22 heating wells. Soil temperatures were closely monitored by 5 monitoring wells, and soil vapor were continuously extracted at -10 kPa. With the heating period of 55 days, the temperature of soil in the centre of the site reached above 350 °C, which was higher than temperatures at other monitoring points. Cavities found in two locations negatively affected temperature rising until they were filled up with concrete. In spite of variations of temperatures among monitoring wells, few disparities have been observed on the removal of PAHs, represented by benzo(a)anthracene (BaA), by GTR. The concentration of BaA in soil at entire 3 depths and all sampling points were below the remedial target after GTR. It was demonstrated that a negative-pressure vapor extraction system enabled BaA partitioning into vapor phase at a much lower temperature than its boiling point. This study set a base for application of GTR for remediation of PAHs contaminated sites.