Lab-Scale Treatability Tests for the Thermal Desorption of Hydrocarbon-Contaminated Soils

Abstract

Within an integrated management plan for contaminated site remediation at a given territorial scale, the performance of treatability tests could be useful and/or expressly requested by the control authority on a site-specific basis to evaluate the overall feasibility of a given remedial option. The thermal desorption process appears to be a favorable treatment technology for organic contaminants. In this context, a particular lab-scale, indirectly heated desorber for treatability tests was originally developed and first applied to natural soils with different textures (silty sand, loam, silt clay, and clayey silt) that were “ad hoc” highly contaminated with diesel oil at various desorption process conditions (heating temperature in the range of 300–390°C, and reactor retention time in the range of 40–120 min). The Italian soil threshold level for heavy hydrocarbons (C > 12) of 50 mg kg⁻¹ (dry matter) was assumed to be the successful goal of the treatability studies. In addition to the individuation of the favorable desorption process conditions for each soil, also in terms of a composite evaluation of heating temperature and retention time, the comparative experimental results provided useful indications of the possible influence of soil texture, the reduction of initial soil organic matter, and the evaluation of kinetic rate constants.

Keywords:

• Hydrocarbon soil contamination
• indirect-heated desorber
• laboratory treatability test
• retention time
• temperature
• thermal desorption

Acknowledgements

The authors would like to thank the staff at the Environmental Chemistry Laboratory and the Sedimentology Laboratory, which are both located at the Scientific Campus of the University of Urbino “Carlo Bo,” for their cooperation and assistance. The authors would also like to acknowledge the reviewers for their unreserved comments, which have improved this revised form of the paper. “Reviewer 1” in particular has inspired the elaboration and evaluation of Figure 9 and Table 3.