Evaluation of mutual connections between zero-valent iron reactivity and groundwater composition in the degradation of trichloroethylene

Zero-valent iron Permeable Reactive Barriers (PRBs) are an efficient and relatively low cost in situ technology for the remediation of aquifers polluted by chlorinated solvents. The groundwater composition and the zero-valent iron reactive material are linked by mutual connections. The groundwater, to a certain extent depending on its composition, is able to oxidize the metallic iron, thus decreasing its reactivity; on the other hand, the dechlorination process and the leaching of chemical species from the reactive substrate may deeply modify groundwater composition. In this study the results of some batch and leaching column tests, performed by means of Connelly iron (Environmental Technologies Inc., Canada) and different aqueous phases (distilled water and an artificial groundwater) are compared, to evaluate the influence of groundwater composition on the reactivity of the iron material for trichloroethylene (TCE) remediation. The degradation mechanisms of the pollutant are discussed. On the grounds of the gathered results the aqueous phase composition shows a strong influence on TCE degradation kinetics obtained by means of Connelly iron; in fact the presence of dissolved substances accelerates TCE degradation