The regeneration of spent granular activated carbon, used in tertiary treatment of municipal waste water, is a three-step process, (1) drying, (2) baking and (3) activating. Laboratory studies with an indirect heated rotary tube furnace demonstrated that the rates at which the drying and baking steps are performed do not have a significant effect on the properties of the baked carbon. The controlling step for the regeneration product is the activation, and the important parameters are the carbon temperature, length of activating time, and steam or carbon dioxide concentration in the activating gas mixture. In multiple hearth furnace regenerations, where the reported carbon losses are 5% to 7% per regeneration, the characteristics of the activating step are: (1) high activating gas input rate, (2) relative short activating time, and (3) relatively low carbon temperature. Thermodynamic calculations made on the hearth furnace regeneration indicate that, by performing only the activation of a previously baked carbon, the hearth furnace gas input rate can be reduced drastically and to the point where it approaches the optimum rate of the rotary tube. (WRSIC abstract)

"Robert A. Taft Water Research Center. Report no. TWRC-7." "Advanced Waste Treatment Research Laboratory - VII." "Submitted in fulfillment of contract no. 14-12-107 between the Federal Water Pollution Control Administration and the MSA Research Corporation." Includes bibliographical references.