EFFICIENCY OF FE0/PUMICE AND FE0/ LAPILLUS GRANULAR MIXTURES IN PERMEABLE REACTIVE BARRIERS

Abstract

This paper presents the results of column tests, carried out in order to evaluate the efficiency of permeable reactive barriers (PRB) composed by zero-valent iron (Fe0) and granular mixtures of Fe0/pumice and Fe0/lapillus. The efficiency of these reactive media was evaluated toward groundwater contaminated by heavy metals, in particular nickel and zinc present in solution at initial concentration of 50 mg/l. Zero-valent iron was mixed with pumice or lapillus in order to preserve the hydraulic conductivity in the long term. Column tests have showed an improved behaviour of the investigated granular mixtures respect to Fe0 used alone in terms of contaminant removal (especially for solutions contaminated by nickel) and in terms of hydraulic conductivity preservation (especially for solutions contaminated by zinc). The Fe0/lapillus granular mixtures have also showed a higher removal efficiency than Fe0/pumice mixtures towards both nickel and zinc