A laboratory pilot study of thermal decontamination of soils polluted by PCBs. Comparison with thermogravimetric analysis

Real soils contaminated with a mixture of polychlorinated biphenyls were thermally decontaminated in a laboratory scale thermal desorption apparatus, under different operating conditions including two operating pressures (P=0.01 and 0.1 MPa), different sample masses (80–320 g), carrier gas flow rates (0–30–280 Nl h−1) and two initial contamination levels. A standard European soil artificially contaminated with 4-chlorobiphenyl was decontaminated using a thermogravimetric analyser (TGA). The same parametric study as cited earlier was performed. With both techniques, the extent of decontamination was studied as a function of temperature during the heating programs (2–3 °C min−1 for the thermal desorption apparatus; 5 °C min−1 for TGA). Only a few differences were noticed between the two techniques. The decontamination starts when the melting temperature of the contaminant is reached (30 °C) and is complete before 350 °C. Thermogravimetric analysis which does not necessitate any chemical analysis appears to be a very attractive technique to investigate the feasibility of a decontamination and to quickly determine the best operating conditions.