Experimental investigation of two-phase extraction on laboratory pilot scale

Multiphase extraction (MPE) is a physical remediation method for soils containing volatile organic compounds. This process allows the rehabilitation of saturated and unsaturated soil zones. Its efficiency is dependent on the operating conditions, which must be optimized. To simulate the MPE, a 2D laboratory pilot was designed. A system of extraction with valve changes was used to reproduce in situ the variation in the extraction well depth. The extracted gas and liquid phases were analyzed over time, and the extraction of pollutants by MPE was observed on a pilot scale. The experiments were carried out using a porous medium model consisting of sand and chosen to have an appropriate permeability for compatibility with MPE. A hydrodynamic study showed the kinetics of soil drying based on the applied process, which revealed a half cone of depression. The pollutant extraction results showed that each increase in depression generated an increase in the extracted concentration of the gas phase. Lowering the level of the extraction well during the MPE allowed more contaminants to be recovered in the liquid phase. It was also found that increasing the concentration of contaminants by a factor of 10 significantly increased the treatment time, which was approximately 2.5 times longer for the same volume of extracted liquid.