Previous studies [1-4] had considered bioregeneration as a single-step process and the rate was assumed to follow the first-order kinetics.In this study, a kinetic model for the bioregeneration of phenol-and p nitrophenol-loaded powdered activated carbon (PAC) and activated rice husk (PRH), respectively, was developed.The kinetic model assumes that bioregeneration has a consecutive mechanism involving a first-order desorption step followed by a first-order biodegradation process.Experimentally, different dosages of PAC and PRH were contacted with phenol and PNP solutions, respectively, at various concentrations during the initial loading step.