A dynamic model for describing the behavior of a biotrickling filters for the treatment of the ammonia odor was developed. At this time, the model was not validated, but independent experiments will later serve to calibrate the model, so that it can be further validated with dynamic and steady-state data from a pilot-scale biotrickling filter. The field biotrickling filter was able to treat up to 3.45 g of ammonia m -3 h -1 with essentially 98% removal, but unstable operation and accumulation of nitrite stimulated the modeling effort. In the future, model simulations will allow to determine the influence of selected parameters on the removal efficiency of ammonia. Of particular importance, was to include in the model the inhibitory effect of free ammonia and free nitric acid on nitritation, i.e., the conversion of ammonia to nitrite and on the nitratation, i.e., the conversion of nitrite to nitrate. The model also includes gas-liquid mass transfer of ammonia, and detailed biokinetic relationships to account for all biological inhibitions encountered during nitrification. When fully developed, the model is expected to be a significant support for the design and operation of biotrickling filter for ammonia control.