Sludge-based activated carbon (SAC) was prepared from paper mill sewage sludge by carbonization at low temperature followed by physical activation with steam in this study and the utilization of SAC in removing Methylene Blue (MB) and Reactive Red 24 (RR 24) from aqueous solutions was investigated. SAC was characterized by iodine number, specific surface area, zeta potential, scanning electron microscope and X-ray diffraction. Adsorption experiments were conducted as function of particle size. SAC dosage, pH, salt concentration, contact time and initial concentration. Desorption of dyes on SAC was studied in deionized water with different pH values and the dye-exhausted carbon was regenerated by thermal treatment. The results showed that the equilibrium adsorption data were well represented by the Langmuir isotherm equation. The maximum adsorption capacity (263.16 mg/g for MB and 34.36 mg/g for RR 24), high regeneration efficiency and low cost (365 US$/t) of SAC provided strong evidence of the potential of SAC for removing dyes from aqueous solutions. (C) 2011 Elsevier B.V. All rights reserved.