Cleaning of excavated soil contaminated with hazardous organic compounds by washing

Abstract

ABSTRACT: Bench‐scale experiments were conducted to investigate the effectiveness of an extraction and washing technique for the cleanup of contaminated soil using surfactants. The organics studied as model contaminants were 1,2,4‐trichlorobenzene (TCB), aniline, phenol, and 2,4‐dichlorophenol (DCP). A sandy loam was used as a model field soil. The results demonstrated the effectiveness of the extraction and washing process for decontamination of the sandy loam soil. As much as 99% of the organic contaminants studied were removed by the process depending upon the compound and the number of washes and rinses. The hydrophilic compounds—aniline, DCP, and phenol—were removed effectively from the soil by washing with deionized water alone. Surfactant washing had no advantage over water washing for these compounds. For the removal of TCB, a combination of washing with surfactant and rinsing with water was required. Alum coagulation was effective in separating clay and colloidal particles from the wash liquid but a relatively high alum dose was required and was observed to enhance adsorption of the contaminants on the clay particles. A small residual contaminant concentration remained in the soil.