Performance of retrievable activated carbons to treat sediment contaminated with polycyclic aromatic hydrocarbons

The feasibility of sediment treatment by magnetized and textile forms of activated carbon (AC) is evaluated in a laboratory well-mixed condition, targeting removal of polycyclic aromatic hydrocarbons (PAHs) from contaminated sediments by amendment of the AC and subsequent AC retrieval. In water, the apparent PAH sorption coefficients for magnetized ACs are comparable to those for a non-magnetized AC, while the textile form of AC exhibits smaller values, which is likely due to the slow PAH sorption kinetics resulting from its thickness. When the magnetized ACs are added in a sediment slurry, the apparent PAH sorption coefficients generally become somewhat smaller than those determined in water, suggesting the sorption attenuation effect by dissolved and/or colloidal organic matter for the ACs. Still, treatment of a PAH-contaminated sediment by 5 dry wt% of the magnetized ACs substantially reduces polyethylene sampler uptakes (by 88-89%). By analyzing PAHs after magnetic separation of the AC particles and sediment, it is shown that significant PAH mass removal can be achieved by the AC-sediment contact followed by AC retrieval. The feasibility of the sediment treatment is challenged by low magnetic particle collection efficiency (50-60%), suggesting that the durability of magnetic susceptibility of the magnetized ACs should be improved.