Evaluation of Indirect-Heated Microwave Thermal Desorption Treatment on Engineering Properties of Lubricant-Contaminated Soil

Featured Application Study on the environmental and geotechnical engineering properties of soil remediated by the indirect-heated microwave thermal desorption method. Soil pollution caused by oil leakage from various industrial facilities such as gas stations, oil plants, military bases, and railway depots has become a serious global environmental and geotechnical issue. The indirect-heated microwave thermal desorption technology has been developed in this study for economical and efficient remediation of oil or organic pollutants. The conclusions were made based on laboratory tests and analyses of the environmental (TPH; total petroleum hydrocarbons) and geotechnical (physical and mechanical) properties of the soil before and after treatments. (1) As the newly-developed equipment was operated for 3 h with the electric power of 32 kW to reach target temperature of 600 degrees C, more than 99.8% of TPH was removed. (2) In the aspect of geotechnical properties, the internal friction angle, maximum dry density and permeability coefficient of the soil were reduced by oil contamination and were finally restored to the almost initial level of the soil after treatment. Therefore, treated soil is expected to be reusable for geotechnical construction purposes such as construction fill materials. (3) It was also found that the developed technology reduces 75% of energy cost and 25% of CO2 emissions for the remediation of lubricant oil-contaminated soil comparing with conventional one.