Effects of Oxidant on Thermal Regeneration of Granular Activated Carbon

Abstract

The effect of oxidant type and flow rate were evaluated in a bench scale study using granular activated carbon (GAC) that had been loaded in a drinking water‐treatment plant and in the laboratory. The rate of regeneration of the GAC was found to be controlled by the rate of steam flow per unit GAC mass. The rate of regeneration increases with increasing steam flow in the range of steam flow rates used for commercial regeneration. At higher steam flow rates, the rate of reaction reaches a plateau value and is insensitive to changes in steam flow rate. Carbon dioxide has little, if any, effect on regeneration. Changing the inert gas flow rate used for fluidization of the GAC had no effect on the rate of regeneration at a fixed oxidant flow rate, even though it affected the oxidant partial pressure. Subbituminous GAC required higher temperatures than lignite GAC to regenerate to a specific apparent density in a fixed time period. Diffusion was not found to control the rate of regeneration. Different types of adsorbates used in a variety of studies were found to form chars of similar reactivity.