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project description

The costs for electrical and also for thermal power increase constantly. Both this and the generally high energy consumption in industrial processes, make energy supply by biogas production (AD anaerobic digestion) a resource saving alternative of providing renewable energy.

The production of 100 L beer results in approximately 24 kg of residues – most of all Brewer’s Spent Grain - which have to be disposed of. Anaerobic digestion is one method to exploit the energy saved in Brewer’s Spent Grain. However, due to its high lignocellulose-content the biogas yields from Brewer’s Spent Grain are only mediocre. Pre-treatment of the residue leads to significantly higher biogas yields.

By pre-treating the substrate thermo-chemically (TC) at high temperatures and under the influence of a catalyst the complex chemical structure of the substrate is broken down. Consequently the pre-treated substrate is more easily accessible to microorganisms of the anaerobic digestion process. But due to chemical reactions thermal by-products occur that might act as inhibitors in the anaerobic digestion process. To find the suitable process parameters for pre-treatment means to find balance between insufficient break down of the complex structure and the production of undesired inhibitors. The challenge of this project is to design the pre-treatment parameters suitable for a stable anaerobic fermentation with a high biogas/methane yield. The aim is to recover the catalyst which can be reused for pre-treatment of fresh substrate. This catalyst loop provides an economical process.
Due to on-site utilisation of the gained biogas, the electrical and/or thermal energy is consumed directly in the industrial plant. Such concepts are implemented effectively in the food and beverage industry (slaughter house, dairy factory), but this approach is completely new concerning the widespread brewing industry. For this reason a demonstration plant will be built and implemented in a brewery. This allows the confirmation and up-scaling of laboratory results.