Biogas potentials from mixed substrates: effect of pre-treatment and co-digestion

Resumé

The aim of this study is to improve biogas potentials through pretreatment
and co-digestion processes. Pre-treatment is important as it can increase the accessibility of microorganisms to cellulose during anaerobic fermentation, especially for highly lignified substrate, and thus increase the biogas potential. Different substrates such as agricultural crops, algae and animal manures are used in this research. Briquetting and extrusion are two main pretreatment techniques that will be analyzed in depth. Different control parameters are manipulated to find the optimal settings
and configuration of the machinery for the highest biogas yield and lowest costs in terms of energy. The influence of co-digestion of plant materials with animal manures is another focus area as it may offer a range of process benefits. Animal manures provide buffering capacity and a wide range of nutrients while plant material with high carbon content balances the carbon to nitrogen (C/N) ratio, thus reducing the risk of ammonia inhibition. Fundamental knowledge about anaerobic digestion of animal manures is investigated first before co-digestion with different substrates is initiated. This is important to fully understand the synergies of anaerobic
digestion involved in biogas production from animal manures
alone.