Subcritical Water Remediation of Petroleum and Aromatic Hydrocarbon-Contaminated Soil: a Semi-pilot Scale Study

Islam, Mohammad Nazrul; Jo, Young-Tae; Park, Jeong-Hun

Subcritical Water Remediation of Petroleum and Aromatic Hydrocarbon-Contaminated Soil: a Semi-pilot Scale Study

2014

Islam, Mohammad Nazrul | Jo, Young-Tae | Park, Jeong-Hun

Due to the unique characteristics of subcritical water, the use of a subcritical water extraction (SCWE) process for the remediation of contaminated soil has become more attractive. Although this process has proved to be effective in lab-scale studies, the knowledge of its capability to treat distinct types of contaminants in a larger scale is still scarce. In this work, a semi-pilot scale SCWE system was used to remove petroleum hydrocarbon (diesel fuel and lubricating oil) and polycyclic aromatic hydrocarbons (PAHs) from contaminated soils. Experiments were carried out at an extraction time ranging from 1 to 3 h and a temperature ranging from 200 to 275 °C, maintaining the minimum pressure where water remains in a liquid state (e.g., 4 MPa at 250 °C). Experimental results showed that the higher removal efficiency was obtained in static-dynamic mode than that for dynamic mode operation. With 2 h (4 cycles of static-dynamic step) of SCWE, 99 % of the diesel fuel was removed from the sand at 250 °C. At the same operating conditions, the silty loam soil showed a removal of 77 % of the diesel, and that was 92 % when the treatment time increased to 2.5 h. At 275 °C, the removal efficiency of PAHs was 91–99 % after 1 h, and that of lubricant oil was 76 % after 3 h. Although the extraction run time increased from 1 to 3 h, it seems to marginally affect the removal efficiency of lubricating oil; rather, it was observed that the effect of temperature is more pronounced.

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