Permeable Reactive Barriers (Proceedings of the International Symposium held at Belfast, Northern Ireland, March 2004). IAHS Publ. 298, 2005, 60-66.

Abstract This modelling study reveals that the sequential use of zero valent iron (ZVI) and granular activated carbon (GAC) can potentially be used for in situ treatment of groundwater with multiple contaminant mixtures, but crucial design rules should be followed, since the performance of the combined system depends on the interplay of both reactor units. As an example a mixture of aliphatic chlorinated hydrocarbons (PCE, TCE, and cis-DCE) and one aromatic chlorinated hydrocarbon (monochlorobenzene) is considered. The results show that the concentrations of less sorbing compounds such as cis-DCE have to be reduced in the ZVI reactor far beyond the desired maximum contaminant level in order to restrict concentration build-ups in the GAC reactor, which occur due to competitive sorption with contaminants withheld in the GAC. Results from reactor modelling studies are used to economically analyse feasible reactor designs. Cost-optimal ZVI-GAC combinations are derived by a general approach based on unit cost ratios.

Key words competitive sorption; dechlorination; economic assessment; granular activated carbon; permeable reactive barriers; pore surface diffusion model; zero valent iron