ZERO-VALENT IRON COLLOID EMPLACEMENT IN SAND COLUMNS

Studies were conducted to evaluate a novel approach of emplacing chemi cally reactive barriers composed of zero-valent iron (Fe-0) by injecti ng suspensions of colloidal-size Fe-0 particles into porous media. The specific objective of this study was to evaluate the effect of influe nt colloid concentration, rate, and volume of colloidal suspensions on Fe-0 colloid emplacement in sand columns. Relatively even distributio ns of Fe-0 throughout a sand column were obtained at low influent coll oid concentrations and high injection rates. As the concentration of i nfluent suspension was increased, a point was reached beyond which a s ignificant increase in the filtration of Fe-0 particles near the front of the column was observed. This point was also found to occur at low er influent colloid concentrations as the injection rate was decreased , i.e., there was an interactive effect of influent colloid concentrat ion and injection rate on the extent of filtration that occurred near the front of the column. As the volume of the colloidal suspension inj ected into the column was increased, the distribution of Fe-0 colloids within the column became increasingly even.