Evaluation of organics leaching from solidified/stabilized hazardous wastes using a powder reactivated carbon...

Cement based stabilization/solidification systems have been widely used to minimize leaching of contaminants from hazardous wastes, particularly for stabilization of wastes that contain heavy metals or other inorganic materials. However, few researchers have demonstrated that stabilization/solidification systems can adequately trap and retain organics present in these wastes. Identification of additives that can be used with the inorganic binder to retain organics has attracted much interest. Activated carbon has been found to be the best additive for immobilizing organic contaminants, but it is generally too expensive for routine use. The use of powdered reactivated carbon was studied in this research to prevent organics from leaching from solidified/stabilized waste forms because it is effective and more economically competitive. The Shrinking Unreacted Core leach test method was employed in this study. Stabilization/solidification waste forms were prepared using five organic compounds--phenol, 2-chlorophenol, chlorobenzene, aniline and Methyl Ethyl Ketone (MEK)--that were spiked into the waste forms at two concentration levels each. Reactivated carbon amounts of 0% (as control), 1% and 2% (w/w) were added into each waste form batch to determine how effectively the reactivated carbon can immobilize those organics and the optimum dose of reactivated carbon addition required. Leachate samples were analyzed using gas chromatography. Results show that 1% reactivated carbon addition is generally enough to reduce leaching of all of the organic contaminants by more than 70%, while a 2% addition reduces leaching for most of the organics to less than 1%.