Malodorous gases such as ammonia, methyl mercaptan, hydrogen sulfide, and trimethylamine give discomfort and harm. The removal of these odors has been studied using impregnated activated carbon fibers (ACFs), where chemicals were present on the surface of ACF to increase the adsorption capacity. From experimental results, cellulose-based ACF shows the best efficiency. In conjunction with the removal of acid odor, ACF impregnated with KI shows high performance, and the optimum impregnation concentration is 9 wt% of KI on the surface of ACF. In addition, H2SO4 demonstrates desirable properties in the removal of basic odor. Total regeneration is achieved by using a hot steam of 250 degreesC, and no change of the adsorption capacity has been observed after regeneration. Various design techniques for adsorption towers have been exploited using pilot-scale apparatus, in which flow rate is 3 m(3)/min. The results show that removal efficiency is as high as that from a bench scale experiment. Moreover, the pilot-scale regeneration process also showed high performance.