Acidogenic fermentation of organic residues for the production of "green" chemicals and new biofuels

Anaerobic digestion has long been used for the production of methane from organic material. Microbial hydrolysis and acidogenic fermentation (acidogenesis) are the first stages of anaerobic digestion and can be investigated as individual processes not only to enhance biomass conversion to methane, but also for the production of “green” chemicals, like volatile fatty acids (VFA). VFA are short chained organic acids, with a carbon number of 2-6 and a variety of uses (e.g. production of bioplastics like poly-hydroxy-alkanoates (PHA), monomers for the chemical industry, synthesis of esters for biofuels). A number of factors affect the profile of acidogenic fermentation, such as the composition of the substrate (residual agro-industrial fractions like fruit pulp, trub, spent grain, spent yeast etc.), the complexity of the mixed microbial communities involved and the experimental conditions (e.g. pH, temperature). Purpose of the research is to evaluate, on the one hand, how these factors influence the concentration and yield of different fermentation products and, on the other hand, whether it is possible to master acidogenic fermentation in order to selectively produce a targeted VFA. Within the context of limited biomass availability and the resulting growth of the biorefinery concept (i.e. multiple valuable products from multiple biomass feedstock), this research will offer information on alternative ways of valorising agro-industrial residue