Kinetics and Simulation of Nitrification in a Rotating Biological Contactor,

A modified biofilm kinetics for a partially submerged RBC process was developed. The proposed kinetics was applied to the nitrification process with and without simultaneous carbon oxidation. A computer simulation of nitrification based on the assumptions for the model development produced an average ammonia flux of the elemental biofilm rotating in the water phase that was almost equal to the flux calculated by the modified kinetics. This provided the reasoning behind the application of the modified steady-state kinetics to a partially submerged RBC in which the biofilm alternately rotates into the water and air. In a partially submerged RBC, the oxygen transfer to the biofilm mainly occurs when the biofilm rotates in the air phase, while the biofilm rotating in the water phase adsorbs the substrates. An equation is shown for the oxygen transfer rate through the attached water-layer or the oxygen flux to the biofilm rotating in the air. A equation is shown for the maximum nitrification flux without simultaneous carbon oxidation.