Abstract:The production, storage and transportation of diesel are likely to cause diesel contamination in soil. Thermal treatment is commonly used to remediate volatile and semi-volatile contaminated soils. However, heating can alter soil properties. This paper gives a comprehensive assessment on the removal efficiency of diesel-contaminated soil using low-temperature thermal treatment (LTTT) and the impact of LTTT on soil physicochemical properties. The optimization results of LTTT experiments showed that the total petroleum hydrocarbon (TPH) removal efficiency was 94% after LTTT at 250 ℃ for 10 min, resulting in a residual TPH concentration of 358.7 mg/kg, lower than the risk screening level of 826 mg/kg. Overheating and/or excessive heating duration can lead to excessive energy consumption and adversely affect the physicochemical properties of soil. The comparison on soil properties showed that soil color changed from yellowish orange to grayish brown, and the slight decreasing trends were observed as follows: soil pH from 7.39 to 6.88, CEC from 16.9 cmol/kg to 14.8 cmol/kg, and water holding capacity from 0.32 g/g soil to 0.29 g/g soil. In addition, soil organic carbon decreased by about 10%, while NO– 3-N and NH4+-N values increased by more than 14 and 4 times, respectively. No significant change was observed in soil texture and total nitrogen. It was inferred based on the elemental analysis and change in soil color that pyrolytic carbon was formed in LTTT process, which was the main removal mechanism of diesel by LTTT in contaminated soil. Therefore, it can be concluded that LTTT is a fast and efficient soil remediation technology, and the optimization of heating temperature and time is the key to make LTTT a green and sustainable remediation technology for applications on diesel-contaminated soil.