Fenton-driven chemical regeneration of MTBE-spent granular activated carbon--a pilot study

Three columns containing granular activated carbon (GAC) were placed on-line at a ground water pump and treat facility, saturated with methyl tert-butyl ether (MTBE), and regenerated with hydrogen peroxide (H2O2) under different chemical, physical, and operational conditions for 3 adsorption/oxidation cycles. Supplemental iron was immobilized in the GAC (≈6 g/kg) through the amendment of a ferrous iron solution. GAC regeneration occurred under ambient thermal conditions (21-27 °C), or enhanced thermal conditions (50 °C). Semi-continuous H2O2 loading resulted in saw tooth-like H2O2 concentrations, whereas continuous H2O2 loading resulted in sustained H2O2 levels and was more time efficient. Significant removal of MTBE was measured in all three columns using $(USD) 0.6 H2O2/lb GAC. Elevated temperature played a significant role in oxidative treatment, given the lower MTBE removal at ambient temperature (62-80%) relative to MTBE removal measured under thermally enhanced (78-95%), and thermally enhanced, acid pre-treated (92-97%) conditions. Greater MTBE removal was attributed to increased intraparticle MTBE desorption and diffusion and higher aqueous MTBE concentrations. No loss in the MTBE sorption capacity of the GAC was measured, and the reaction byproducts, tert-butyl alcohol and acetone were also degraded.