Solidification Stabilization Of Organic Hazardous Wastes Using Reactivated Carbon PDF Download

Cement based stabilization/solidification (S/S) systems have been widely used for immobilization of contaminants in hazardous wastes, particularly for stabilization of wastes that contains heavy metals. However, few have demonstrated that S/S systems can adequately trap and retain organics, since heavy metals in S/S processes are converted into insoluble precipitates, and this does not happen with most organics. Additives that can be used with the inorganic binder to retain organics or render them less hazardous have attracted much interest. Research has found activated carbon to be the best additive for immobilizing organic contaminants. Powdered reactivated carbon was used in this research to retain organics from leaching because it is effective and economically competitive. The cost of reactivated carbon is much less than one-fourth of that for virgin carbon, making its use more attractive to the S/S industry. A difficulty with evaluating S/S systems for immobilization of organics is the lack of a suitable leaching test procedure. The objective of this research was to evaluate the use of leaching tests defined for measurement of inorganic leaching for measurement of organic leaching. The Shrinking Unreacted Core (SUC) leach test method, which was developed by Dr. Paul L. Bishop's research group at the University of Cincinnati, was employed in this study. S/S waste forms were prepared and five organics l phenol, 2-chlorophenol, chlorobenzene, aniline and Methyl Ethyl Ketone (MEK) l were spiked into the waste forms at two concentration levels each. 0% (as control), 1% and 2% reactivated carbon (w/w) were added into each batch of waste forms to determine how effectively the reactivated carbon can immobilize those organics and the optimum dose of reactivated carbon addition. Leachate samples were analyzed using Gas Chromatography. Results show that 1% reactivated carbon addition is enough to reduce leaching of most of the organic contaminants by more than 70%. The leaching behaviors fit the SUC model.