Analysis of thermal processing applied to contaminated soil for organic pollutants removal

• PAHs behavior during pyrolysis used for soil decontamination is investigated.
• Concentration levels of PAHs from the pyrolysis products are reported.
• Pyrolysis is an efficient process for removal of the analyzed PAHs from soil.
• Pyrolysis efficiency strongly depends on the operational conditions of the process.
• Increasing information will increase quality of environment.

The paper presents the results of an experimental study conducted to investigate PAHs behavior during non-oxidant thermal decontamination of soil samples contaminated with petroleum products. The study focused on the assessment of the concentration levels for different PAHs species present in pyrolysis products after the treatment of contaminated soil samples. Pyrolysis experiments were performed using a horizontal tubular reactor. The contaminated soil samples were treated in inert controlled atmosphere (nitrogen). The treatment period varied between 30 and 60 min at a temperature range of 350 °C–650 °C. Chemical analyses were performed to compare the thermal degradation mechanism and the pollutants generation in the flue gases of the pyrolysis process. The present research study identifies and quantifies the concentration level of polycyclic aromatic hydrocarbons from the solid and gaseous phases of the pyrolysis products, as well as from the condensates produced during the process. The amount of the organic contaminants was determined using a GC/MS analyzer and Soxhlet extraction method. The results of the experiments revealed that pyrolysis is an efficient process that could be used to remove the PAHs from contaminated soil. For 650 °C treatment temperature performed for 30 min the thermal process registered a decontamination efficiency superior to 80%. The extension of the treatment period to 60 min increased the decontamination efficiency to more than 90%.