Remediation of diesel-contaminated soil by low-temperature thermal desorption

Abstract

Site contamination by petroleum hydrocarbons is a widespread environmental problem in the world. One of the methods used to cleanup petroleum compounds from contaminated soils is low-temperature thermal desorption (LTTD) that uses heat to evaporate volatile pollutants from the soil. The remediation of contaminated soil by diesel using the LTTD method was studied. The effect of temperature (180 and 340 °C), residence time (from 5 to 20 min) and soil texture (two different types containing sand, Bentonite clay and Kaolinite clay) was investigated. By using the LTTD method, the maximum removal efficiency of diesel from soil type A (30% sand, 50% Kaolinite, 20% Bentonite) was 95.6% at 340 °C during a period of 20 min. Moreover, the diesel removal rate was higher in samples containing a higher percentage of Kaolinite than of Bentonite. By applying a temperature range of 180–340 °C to soils contaminated by diesel with an initial concentration of 20,000 mg kg−1, the cleanup standards of diesel range organics contaminated soils can be achieved after 23 min. The costs of thermal remediation may be reduced by reusing the waste heat generated in several industries and may cover the required heat for the LTTD process and the selected range of temperature.