BACKGROUND: High concentrations of phenol in wastewater are difficult to remove by purely biological methods. Chemical oxidation is one way to treat high concentrations of phenol but complete oxidation will make the treatment process uneconomical. For the purpose of integrating chemical and biological treatment, the oxidation of phenol using chlorine dioxide was investigated in a medium suitable for bioremediation. The effects of chlorine dioxide concentration (500 to 2000 mg L-1), temperature (10 to 40 degrees C) and pH (3 to 7) on the oxidation of 2000 mg L-1 of phenol were determined. RESULTS: Chlorine dioxide concentration was found to be the dominant parameter for the removal of phenol in the nutrient rich medium. The optimal concentration of chlorine dioxide to completely oxidize 2000 mg L-1 of phenol was 2000 mg L-1. Compared with Fenton's reagent, half as much chlorine dioxide was needed to oxidize 2000 mg L-1 phenol. The reaction of chlorine dioxide with phenol was very fast and reached equilibrium within 10 min. The main oxidation products were identified as 1,4-benzoquinone and 2-chloro-1,4-benzoquinone. CONCLUSION: Compared with Fenton's reagent, chlorine dioxide is a superior oxidant for removal of phenol from both pure water and bioremediation medium. (C) 2010 Society of Chemical Industry