MODELING OF HYDROGEN BEHAVIOR AND REDUCED PRODUCT FORMATION FOLLOWINGPERTURBATION WITH HYDROGENIC SUBSTRATE IN A METHANOGENIC REACTOR

The purposes of this study are to develop a non-steady state model whi ch can express hydrogen behavior and reduced products formation in a p erturbed methanogenic CSTR and to investigate energetic and kinetic in teraction such as hydrogen transfer between H-2 producers and consumer s. Smith and McCarty (1989a, 1989b) obtained interesting experimental results on transient responses of the perturbed mixed-culture methanog enic CSTR receiving ethanol and propionate. In an experiment with a su dden addition of propionate and ethanol at steady state, they observed highly elevated H-2 pressure and formation of reduced products such a s propanol and longer chained VFAs. The model was applied to the pertu rbation experiment introducing a new concept of H-2 transport between bacterial groups, Different H-2 concentrations are defined by making a hydrogen transport within a colony of H-2 producers and consumers, Th e modified model expressed the sudden change of H-2 pressure and the f ormation of the reduced intermediate products which brought relatively low H-2 concentration. Once kinetics and energetic of biochemical rea ctions are given, the model could be available for transient processes and for better understanding of interactions between H-2 producers an d consumers. (C) 1997 IAWQ. Published by Elsevier Science Ltd.