EXPERIMENTAL ASSESSMENT OF CHROMIUM IMMOBILIZATION IN CONTAMINATED SOIL BY IN SITU CHEMICAL REDUCTION

The aim of the present research was to compare the effectiveness of iron sulfate and nano zero valent iron in the chemical reduction of Cr (VI). The experiments were performed on a soil collected at an industrial site: it also resulted polluted by nickel, as a result of a long-term industrial activity. The experimental tests were performed under several operating conditions: the main parameter investigated were the amount of chemical with respect to chromium content, the presence of oxygen in the slurry, and the liquid (L) vs. solid (S) ratio. The soil was fully characterized after each tests, to perform mass balances, and sequential extractions were carried out to assess the metals mobility induced by the washing with the solution containing the reducing agent. Results show that iron sulfate successfully reduced Cr (VI): within 16 hours of treatment the residue amount of all the investigated metals was below the threshold allowed by Italian Environmental Regulation for an industrial reuse