Potassium permanganate oxidation of low-permeability phenanthrene contaminated soil under fracturing conditions

Abstract

In situ chemical oxidation (ISCO) technology has limitations in the remediation of low-permeability polycyclic aromatic hydrocarbon (PAHs)-contaminated sites because of the difficulty in oxidant delivery. Horizontal fractures created by hydraulic fracturing provide convenient channels for rapid oxidant delivery. However, limited studies have focused on potassium permanganate (KMnO4) oxidation in low-permeability PAH-contaminated sites under fracturing conditions considering in situ hydrological environments. Therefore, this study aimed to explore the effect of KMnO4 concentration on the remediation efficiency (including the removal rate of phenanthrene (PHE), remediation time, and total oxygen demand (TOD)) of low-permeability PHE-contaminated soil through a one-dimensional penetration-oxidation test, and the effect of KMnO4 oxidation on the physicochemical properties of the soil through a series of laboratory experiments. The results showed that an increase in KMnO4 concentration shortened the remediation time and increased the removal rate of PHE and TOD from PHE-contaminated soil. The oxidation of KMnO4 resulted in an increase in the pH, oxidation-reduction potential, dissolved organic carbon, cation exchange capacity, specific surface area, and fine particle content of the soil, and a decrease in the total organic carbon of the soil, but did not alter the permeability of the soil.