Microwave-Assisted Thermal Remediation of Diesel Contaminated Soil

Leakage of petroleum products, gasoline and diesel, at gas station had become one of major soil contamination sources in Taiwan. Total number of 154 petroleum contaminated gas stations was successively ascertained since the implementation of Soil and Groundwater Remediation Act in 2002. One of the contaminated gas stations, mainly diesel polluted, was studied for the feasibility of microwave-assisted thermal remediation. The average of total petroleum hydrocarbons (TPHt) in hotspot of this site was 2,845 mg/kg exceeding regulatory limit (1,000 mg/kg). According to the groundwater condition in the site, soil samples treated by microwave radiation with and without water as saturation and vadose zones were respectively tested in laboratory. The results show that a 12-min microwave energy can heat soil with water to reach 235 degrees C and degrade its TPHt to 934 mg/kg; additionally, a 5-min microwave energy can heat soil without water to reach 220 degrees C and degrade its TPHt to 520 mg/kg. Both soil samples passed TPHt regulatory limit and microwave remediation with fast and effective advantages for petroleum products contaminated soil was also verified.