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ACTIVATED CARBON PROCESS FOR TREATMENT OF WASTEWATERS CONTAINING HEXAVALENT CHROMIUM
Citation:
Huang, C. AND A. Bowers. ACTIVATED CARBON PROCESS FOR TREATMENT OF WASTEWATERS CONTAINING HEXAVALENT CHROMIUM. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/2-79/130 (NTIS PB300765), 1979.
Description:
The removal of hexavalent chromium, Cr(VI), from dilute aqueous solution by an activated carbon process has been investigated. Two removal mechanisms were observed; hexavalent chromium species were removed by adsorption onto the interior carbon surface and/or through reduction to the trivalent state at the external carbon surface. The effects of Cr(VI) concentrations, pH, carbon dosage and extent of mixing in the reaction vessel were studied in the batch mode and in continuous flow packed column experiments in the laboratory. The adsorptive capacity of the carbon and the rates of Cr(VI) adsorption and reduction have been determined. Thermal regeneration of the exhausted carbon was examined, along with caustic or acid stripping solutions and a combined caustic-thermal process. A case study was presented and the experimental data and rate expressions obtained from the data were used to evaluate the design variables (i.e., pH, carbon dose, Cr(VI) concentration and mixing in the reaction vessel). Several Cr(VI) treatment schemes were proposed, together with an economic analysis of each scheme.