Highly hydrophobic contaminants are easily adsorbed from aqueous solutions. Since for many of these compounds sorption increases with increasing organic carbon content, natural materials, such as bituminous shales and coals may be used in permeable sorptive walls. This, however, only applies if sorption is at equilibrium, which may not always be the case in groundwater treatment system. In contrast to the natural solids, granular activated carbons (GACs) have very high sorption capacities and reasonably fast sorption kinetics. The laboratory results show that the application of GACs (e. g. F 100) is economically feasible for in situ removal of polycyclic aromatic hydrocarbons (PAH) from groundwater at a former manufactured gas plant site (MGP). For less sorbing compounds (such as benzene, toluene, xylenes) a combination of adsorption and biodegradation is necessary.
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