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The application of soil washing for treatment of polycyclic aromatic hydrocarbons contaminated soil: A case study in a petrochemical complex



Polycyclic aromatic hydrocarbons (PAHs) are potential carcinogenic and hazardous compounds having raised appreciable environmental concerns around the world in recent decades. This research investigates the effect of soil washing on removal of PAHs in contaminated soil. The study was conducted by collecting soil samples from a petrochemical complex in south of Iran. Testing was carried out at three temperatures of 20°C, 40°C, and 80°C and washing periods of 30 min and 60 min. Moreover, two different concentrations of Triton X-100 and Brij 35 surfactants were used throughout the experiments. The results of this research indicated that the maximum removal efficiency of PAHs was obtained using Brij 35 at concentration of 5 g/L, temperature of 80°C and washing duration of 60 min. The highest removal efficacies for anthracene, naphthalene, fluorene, and benzo(a)pyrene in coarse and fine fractions of the samples occurred at 76.24%, 86.32%, 78.54%, 85.81% and 57.50%, 63.39%, 60.87%, 79.94%, respectively. Moreover, the highest removals of total PAHs are 81.66% and 61.49%, accordingly. Furthermore, using Brij 35, benzo(a)pyrene presented maximum changes in of PAHs in the samples. It is due to the high solubilizing ability of Brij 35 for benzo(a)pyrene, its low adsorption onto soil, and also its lower CMC in comparison with the other surfactant. According to the results, the higher the surfactant concentration, washing time, and temperature are, the more removal efficiency will be. For the parameters tested, the rates of PAHs removals from the samples decreased in the order of surfactant concentration, temperature and washing duration, respectively. © 2013 American Institute of Chemical Engineers Environ Prog, 33: 107–113, 2014