THE ROLE OF COMETABOLISM IN THE BIOREGENERATION OF GRANULAR ACTIVATED CARBON COLUMNS

Activated carbon adsorption isotherms were performed along with biological kinetic studies to describe biologically-active GAC column performance. A continuous-flow GAC bioregeneration experiment was then conducted using a mixture of biodegradable (toluene) and traditionally nonbiodegradable (trichloroethylene, [TCE]) SOCs. The GAC was pre-equilibrated with respect to toluene and TCE to observe the biggest effect on bioregeneration performance. Despite initial dissolved oxygen limitations, the biodegradable SOC effluent concentration decreased over time and then remained low, after which the traditionally nonbiodegradable SOC effluent concentration also decreased because of the increased availability of adsorption sites on the GAC as well as the cometabolism of TCE by enzymes produced via the toluene degradation pathway (when iron was present). Cometabolism-based bioregeneration ranged from 2.9 to 4.2% of the initial loading after 20 days. These results illustrate an increase in GAC service life for cometabolizable SOCs through bioregeneration of GAC containing biodegradable SOCs.