Modelling the production of VFA from proteins by mixed culture fermentations

Abstract

Mixed-culture fermentations (MCF) are recognised as a valid process to yield added-value products from organic wastes in the form of volatile fatty acids (VFA). The use of mixed cultures is attractive due to their economical and operational advantages (e.g. no sterilisation is needed). However, they also pose a fundamental challenge: they are complex and their regulation mechanisms remain still unclear. One of the main limitations of the process is its low product selectivity: the productivity of the different VFA is highly dependant on operational conditions (e.g. pH, retention time or feeding characteristics). In consequence, developing bioprocesses based on this technology remains a challenging task. In this context, we aim at establishing a model-based methodology for developing novel bioprocess using MCF. The emphasis is placed on two aspects: to reach a high productivity and a high selectivity on the desired VFA(s). The improvement of selectivity is carried out by means of a metabolic energy-based model while the productivity is maximised using a general kinetic-based model