Effect of Redox Potential on Leaching from Stabilized/Solidified Waste Materials

Abstract

The effect of redox potential on leaching from solidified/stabilized fly ash and flue gas desulfurization sludge wastes was studied. In all cases, metal leaching from both raw and fixed wastes was below regulatory limits as defined by the Toxicity Characteristic Leaching Procedure (TCLP) test, and the wastes can be considered nonhazardous. All raw waste leachate concentrations were significantly higher than drinking water limits, though. Research showed that redox potential has a significant effect on metals leaching. Chromium leaching increased significantly under highly oxidizing conditions (+250 to +500 mV), very little leached at an ORP of +50 mV or less. Arsenic, vanadium, lead and iron leaching rates all increased significantly under reducing conditions. © 1992 Air & Waste Management Association.