To illustrate the process of nitric oxide (NO) denitrifying removal by a novel rotating drum biofilter (ROB), a dynamic model has been developed and further validated. Based on the mass component profile of NO at the gas-liquid interface combined with a Monod kinetic equation, the model was used to depict the mass transfer-reaction process of NO in RDB, focusing on the concentration distribution of NO in the gas, liquid, and biofilm phases. The NO distribution equation on the biofilm carrier was thereby achieved, as well as a dynamic model for NO elimination in the test system. Additionally, effects of operating parameters such as inlet NO concentration and empty-bed residence time on NO removal efficiency were evaluated through a sensitivity analysis of the model. The model was then modified taking the absorption of NO by nutrition liquid in the bottom of RDB into consideration. The results showed that the simulated data agreed well with the experimental data. The model made it possible to simulate a relatively high NO removal efficiency by RDB. (C) 2009 Elsevier B.V. All rights reserved.