Membrane-assisted removal of hydrocarbons from contaminated soils—laboratory test results

Abstract

The effectiveness of soil remediation process, consisting of the soil washing, microfiltration and pervaporation process to remove iso-octane (VOC) was investigated. The several different parameters influencing the washing process were investigated: type of the soil (sand and sandy clay), time of the washing process as well as an addition of surfactants to the washing solution. The MF-enhanced soil washing allowed for the removal of iso-octane from the contaminated soil. Efficiency of iso-octane removal depended on the type of soil and was worse for the sandy clay, because of its higher stickiness and plasticity. The addition of a surfactant enhanced iso-octane removal; however, its optimal concentration in washing solution should not be higher than 0.1–0.3 wt.%. A substantial excess of a washing solution to the soil (at least 100:1) was needed to obtain a good removal of volatile organic compounds (VOCs) from contaminated soil. Iso-octane extracted from the contaminated soil was subsequently removed by pervaporation process with several types of hydrophobic membranes. Prior to pervaporation process, the washing solutions underwent microfiltration to remove all suspended particles from the feed. The best pervaporative properties were found for the PDMS-PAN membrane. An addition of the surfactant increased the solubility of iso-octane in water during the washing step of remediation process but simultaneously dramatically decreased the efficiency of the final removal of VOCs from water by pervaporation.