Rigorous steady-state models of acetate- and methanol-utilizing methanogenic biofilms are developed taking into account the mass transfer of neutral and ionic species, pH changes within the biofilm, pH-dependent Monod kinetics, chemical equilibrium, electroneutrality, gas production within the biofilm, and the presence of a concentration boundary layer (CBL). The study shows that significant differences can exist between the flux predictions using the traditional models and when pH changes within the biofilm are taken into account. The biofilm models are coupled to a model of a completely-stirred tank reactor (CSTR) and strategies for the optimization of biofilm reactor performance are examined. (Copyright (c) 1993 Water Environment Federation.
