This demonstrates that the biodegradation of phenanthrene by microorganisms accelerated the mass transfer of phenanthrene from the solid to aqueous and micelle phases, when compared with the results of the desorption test for the soil slurry system. Also, in the clay slurry, the phenanthrene desorption had a similar inclination as with the sand, though the rate and extent of desorption was lower than that of the sand. This was probably due to the higher content of organic material, as previously mentioned.