Using municipal wastewater sludge as raw material, sludge activated carbon was prepared by ZnCl₂ activation agent and addition of adequate additive. Its structure and absorption were characterized by means of adsorption isotherms, XRD, BET, FT-IR, SEM, etc., and its fractal dimension D value was determined by the method of adsorption from solution. The results show that the activated carbon produced under the condition of favourable pyrolyzation temperature, solution concentration of ZnCl₂-immersed sludge, particle diameter of the raw material and adequate additive, exhibited BET surface area of 634.8～748 m²•g^－1 and the most probable pore size of ca. 4.16 nm. Its IR peaks of C—OH, C—H, N＝O and C＝C confirmed existence of corresponding function groups. It has narrow mesoporous structure with parallel wall. The obtained fractal dimension D value of the sludge activated carbon derived by the method of adsorption from solution is close to 2. The sludge activated carbon can be characterized by low fractal dimension.

Key words: wastewater sludge, activated carbon, structure characterization, fractal, absorption from solution