Evaluating 3-D and 1-D mathematical models for mass transport in heterogeneous biofilms

Results from a three dimensional model for heterogeneous biofilms including the numerical solution of hydrodynamics were compared to simplified one di mensional models. A one dimensional model with a variable diffusion coeffic ient over the thickness of the biofilm was well suited to approximate avera ge concentration profiles of three dimensional simulations of rough biofilm s. A new compartmentalized one dimensional model is presented that is then used to evaluate effects of pores and channels on microbial competition in heterogeneous biofilms. Surface and pore regions of the biofilm are modeled using separate compartments coupled by a convective link. Local concentrat ion profiles from the three dimensional simulations could be adequately rep roduced using the compartmentalized one dimensional model. The compartmenta lized one dimensional model was then used to evaluate bacterial competition in a growing biofilm and in a mushroom type biofilm assuming different mod es of detachment.