Fresh water shortage is one of the greatest problems of modern society; as a result, water desalination, particularly with membrane processes, is becoming increasingly important, since it makes possible the use of brackish water for potable water, or the reuse of lower-quality water for industrial, irrigation, or other uses. Membrane processes used in water desalination and wastewater treatment are often affected by the degradation of biofouling, in which biofilms play a critical role, thus making biofilm simulation models very relevant. Biofilms are highly complex and heterogeneous systems, containing cells distributed in a non-uniform manner in polymers. Two classes of models, the cellular-automata and the individual-based models, which are used to simulate the growth and development of biofilm structures as a result of microbial growth in different environmental conditions, are presented. After a short review of models presented in the last decade, we identify similarities and differences and present the environmental conditions that can be best simulated with each model type. (C) 2009 Elsevier B.V. All rights reserved.