Abstract The feasibility of using whole cell microorganisms to regenerate spent granular activated carbon (GAC) was investigated. Regeneration of 2,4‐D loaded activated carbon by Pseudomonas isolates was observed for bioregeneration times of 18–96 hours, and initial bacterial concentrations of 7.17x105 to 7.17x107 CFU/mL. Pore surface recovery decreased with increasing initial bacterial concentrations suggesting that bacteria may have blocked the pores. Regeneration efficiency of larger pore diameter GAC was found to be higher, indicating that bacteria could not access 2,4‐D loaded sites where the pore diameter was small However, at high initial bacterial concentrations, increase in bioregeneration time increased pore surface recovery indicating that intermediate metabolite products (IMPs) of 2,4‐D were further metabolized. The bioregeneration process changed the adsorption equilibrium and adsorption kinetics characteristics of the original activated carbon. The carbon pore structure was found to influence the process of bioregeneration. Key words: Activated carbonsorptionbioregeneration2,4‐D Pseudomonas pseudoalcaligenes, Biot numbersurface recovery Notes To whom correspondence should be addressed