Bituminous Soil Remediation in the Thermal Plasma Environment

Abstract

Petroleum hydrocarbons like diesel, crude oil, and bitumen are persistent soil contaminants, necessitating urgent remediation due to their harmful effects on the soil and living organisms. Plasma remediation is a thermochemical method that is gaining attention as an alternative to soil de-pollution. Accordingly, the purpose of this experimental research is to investigate the feasibility of thermal air and water vapour plasmas to de-pollute bituminous soil. Pre-/post-remediation of soil and generated products, an analysis was carried out using SEM, EDX, TGA, and elemental and gas analysers. Despite the plasma type, the research showed that the bituminous soil’s surface morphology changed and resembled clean soil after the remediation. The EDX analysis revealed that the carbon content in the soil reduced from 70.14 wt.% to 7.70 wt.% and 5.74 wt.% and the sulphur concentration decreased from 2.64 wt.% to 0.70 wt.% and 0.74 wt.% after treatment in the environment of water vapour and air plasmas, respectively. The gas analysis revealed that bitumen was mainly decomposed into a synthesis gas (H2 + CO) and CO2, with concentrations ranging from 8.67% to 13.66% and 10.89% to 12.82% when air and water vapour plasma were used. Thus, both thermal plasmas effectively remediated soil, with the bitumen concentration not being detected or below the laboratory’s finding limit (<0.089 g/kg).