A model for a nitrifying suspended-growth reactor incorporating intraparticle diffusional limitation

A mathematical model for a nitrifying suspended growth reactor that incorporates intraparticle diffusional limitation is presented. A parameter describing the physical characteristics of floc was introduced to overcome the experimental difficulties in determining floc characteristics. Model validation was carried out by comparing the estimated values of the half-velocity constants for the dissolved oxygen effect on Nitrosomonas and Nitrobacter obtained using the model with and without diffusional limitation terms. A sensitivity analysis revealed the results were affected by uncertainties in assigning values to the kinetic coefficients, but the probability for significant diffusional limitation was high. The significance of the model was demonstrated through computer simulation where the interaction between the floc characteristics parameter (influenced primarily by mixing intensity) and dissolved oxygen were predicted to be significant in influencing nitrogen removal.