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Fenton- and Persulfate-driven Regeneration of Contaminant-spent Granular Activated Carbon
Citation:
Huling, S. AND S. Ko. Fenton- and Persulfate-driven Regeneration of Contaminant-spent Granular Activated Carbon. Presented at 18th International Conference on Advanced Oxidation Technologies for Treatment of Water, Air, and Soil, November 12 - 15, 2012.
Impact/Purpose:
P.Pt. presentation at the 18th International Conference on Advanced Oxidation Technologies for Treatment of Water, Air, and Soil, Crowne Plaza Riverfront, Jacksonville, FL, Nov 12-15, 2012.
Description:
Fenton- or persulfate-driven chemical oxidation regeneration of spent granular activated carbon (GAC) involves the combined, synergistic use of two treatment technologies: adsorption of organic chemicals onto GAC and chemical oxidation regeneration of the spent-GAC. Environmental contaminants are immobilized and concentrated on the GAC, and subsequently transformed by hydroxyl or sulfate radicals and other reaction intermediates. Objectives of the treatment process are to transform the contaminants into less toxic byproducts, re-establish the sorptive capacity of the GAC, increase the useful life of the GAC, and reduce costs for GAC regeneration and water treatment. A summary of the major findings of fundamental mechanisms in the treatment process will be presented. Results will also be presented from two pilot-scale studies where slip-streams of either methyl tert-butyl ether (MTBE) or trichloroethylene (TCE) contaminated ground water was treated with GAC and subsequently chemically regenerated. GAC regeneration is functionally dependent on multiple factors including iron (Fe) content, temperature, GAC particle size, pH, H2O2 and persulfate concentrations and application rates, and alteration of the surface functionality of the GAC surface. Correlations between GAC particle size and H2O2 reaction rate, MTBE oxidation, and H2O2 penetration depth were established. Similarly, a correlation was established between temperature and oxidant reaction rates, MTBE oxidation, and MTBE desorption and diffusion in GAC. Fe distribution results and modeling H2O2 diffusion and reaction in GAC were used to assess H2O2 penetration in the GAC and the dimensions of the “reaction zone” in the GAC particle. Understanding the physical dimensions of the reaction zone within the GAC particle was correlated to the level of MTBE oxidation achieved. Through these experiments, an increase in the mechanistic understanding of rate limiting steps in GAC regeneration was establish