Pilot Scale and Theoretical Study of Thermal Remediation of Soils

Abstract

During the last decade, low temperature thermal treatment of polluted soils has been developed as an alternative treatment to the soil incineration, especially for soils contaminated with volatile organic compounds. In this paper, the thermal desorption process is studied using an industrial pilot operating continuously (30 kg of soil per hour). The influence of some operating parameters (temperature, flow rate, and pressure) on the decontamination level is tested. Results are compared with batch experiments (thermogravimetry and laboratory scale pilot). They show that the operating temperature is the determining decontamination parameter followed by the gas flow rate and finally, to fine the results, the operating pressure, which can be lowered. A one-dimensional model based on the pollutant evaporation is developed to predict the parameter values necessary to obtain a good decontamination level. This model implies the fitting the pollutant decontamination enthalpy. This value represents the complex pollution of a real soil and leads to good prediction of the model. This model is a good tool to investigate the effect of the different operating parameters and to estimate the extent of decontamination.