Wet Oxidation of Fine Soil Contaminated with Petroleum Hydrocarbons: A Way towards a Remediation Cycle

The aim of this experimental study was to assess the feasibility of using a wet oxidation (WO) process for treating fine soil with a high level of total petroleum hydrocarbons (TPHs). Two samples of soil were spiked with two different contaminants (motor oil, and motor oil + diesel). The samples were subjected to a WO bench plant test, where the effect of the main process parameters (i.e., temperature and reaction time) on the removal of TPHs was investigated. Results show that the WO process is effective for the decontamination of hydrocarbons, and a strong reduction (>85%) can be obtained with the typical working conditions of a full-scale plant (temperature = 250 C, reaction time = 30 min). The solid residue resulting from the WO process was characterized in order to evaluate the recovery options. In terms of chemical characterization, the contents of the pollutants comply with the Italian regulations for commercial and industrial site use. Moreover, the results of the leaching test suggested that these residues could be reused for ceramic and brick manufacturing processes.