MATHEMATICAL-MODELING OF MIXED-CULTURE BIOFILMS

About 10 years ago a set of mass balance equations for mathematical mo deling of mixed-culture biofilms (MCBs) was presented. That model was able to describe the progression of the biofilm thickness and the spat ial distribution and development in time of particulate and dissolved components in the biofilm as a function of transport and transformatio n processes. Experimental observations made in the past years have sho wn that some of the assumptions made in that MCB model were too simple . Therefore, an extended MCB model with additional processes has been developed. This model includes a more flexible description of transpor t of dissolved components in the biofilm and considers diffusive trans port of particulate components in the biofilm solid matrix, changes of the biofilm liquid phase volume fraction (porosity), and simultaneous detachment and attachment of cells and particles at the biofilm surfa ce. The extended MCB model is implemented in AQUASIM, a new computer p rogram designed for the analysis of aquatic systems, which is used her e to illustrate and discuss the effect of the additional processes on MCB behavior. (C) 1996 John Wiley & Sons, Inc.