The depollution test was carried out through the surfactant washing process. The effects of variation in SDS concentration (0.5-1 g/L), contact time (10-60 min) and soil particle size (<50 μm – <250 μm) were studied on the efficiency of depollution through a complete factorial plan. Quantitative analyzes performed on the different fractions of a soil sample showed that the fine fraction (<50μm) is the most polluted. In fact, the contents of n-alkanes in soil particles of sizes <50 μm range from 4.79 to 65.90 μg/g of sample MS and in sizes of <250 μm, from 0.91 to 30 μm, 70 μg/g of MS. PAH contents in fractions <50μm range from 3.46 to 103.5 μg/g of sample MS and in fractions <250 μm, from 2.90 μg/g to 21.85 μg/g of MS. These hydrocarbon levels obtained are much higher than the guide values defined by the French Environment and Energy Management Agency. The application of this washing process has made it possible to achieve overall hydrocarbon abatement rates of up to 97.3%. As a result, the optimum for the minimum content of residual hydrocarbons (≈10 μg/g DM) is obtained at a concentration of 0.75 g/L, a contact time of 60 min and a particle size of soil < 50 μm. This process, which makes it possible to obtain an interesting yield of extraction of pollutants, could thus be used for the remediation of soils and sediments polluted by hydrocarbons in general and PAHs in particular.
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