In the solid phase, the phenanthrene concentration for the sand slurry decreased at a high rate as a result of desorption. More than 90% of the phenanthene was desorbed into the aqueous phase and micelle phase within 12 h for the sand slurry system. 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.