GRANULAR IRON REACTIVE BARRIERS FOR THE DEGRADATION OF CHLORINATED SOLVENTS IN GROUNDWATER / Nedbrytning av klorerade lösningsmedel i grundvatten med hjälp av granulärt järn reaktiva barriärer
This paper presents the results of batch and column experiments that investigated the degradation of chlorinated solvents bv zerovalent granular iron. These experiments were designed to produce data essential for the installation of a field-scale permeable reactive barrier at a field site with groundwater contaminated bv perchloroethylene (PCE) and other less chlorinated ethenes. The batch tests were conducted in order to identify a suitable iron product for the reactive matrix in a barrier. The test results indicated that an American iron product, because of its greater surface area, was superior in the degradation of PCE relative to other selected granular iron products. The column experiments were designed to determine the rates of PCE, TCE and cis-DCE removal and the column residence times needed to achieve solvent degradation. For a column composed of a mixture of 50% granular iron and 50% sand, the results showed that the time for a 50 % decrease (t50) in solvent concentration was < 1.3 hours for PCE, ca. 1.4 hours for TCE, and ca. 1.9 hours for cis-DCE. These results can be used to dimension a field-scale reactive barrier, where the groundwater residence time must be in excess of these t50 values.