Abstract: The effects of toluene, petroleum ether,compound solvent of hydrocarbon and alcohol, naphtha and gasoline as solvent on the extraction of organic pollutants from tank bottom oil sludge were investigated. The optimum extractants were selected to obtain a compound extractant with high extraction rate. The effects of the ratio of extractant to sludge, extraction temperature, extraction time and stirring rate on the extraction efficiency were studied, and the content of polycyclic aromatic hydrocarbons (PAHs) in the extracted organic pollutants and tailings was also determined. The results showed that the extraction rate could reach more than 95%, and the extraction volume could reach 0.159 0 g/mL, when the compound extractant ratio (toluene/compound solvent of hydrocarbon and alcohol) was 6:4, the ratio of extractant to sludge was 3, the extraction temperature was 70 ℃, the extraction time was 30 min, and the stirring rate was 1 000 r/min. The total content of PAHs in the extracted organic pollutants was 1 579.87 μg/g, and carcinogens (∑CPAHs) accounted for 44%, indicating that there was a great potential carcinogenic risk. The PAHs of tailings was less than 6 μg/g, which could be directly discharged or used as garden land and pasture soil without harm to the environment.

Key words: oily sludge, organic pollutant, extration, polycyclic aromatic hydrocarbons