B. HAEFFNER (1), K. Sommer (1); (1) Technische Universität München -
Chair of Process Engineering of Disperse Systems, Freising, Germany
Poster
Energy from waste materials of the brewing process plays a rising role
in breweries. Today and in the future, it will become very difficult for
breweries to dispose of their residues. Due to new regulations and
higher standards for waste treatment, producers are forced to find new
ways for cost-neutral discharge of their biological waste that also
meets regulatory requirements. Brewery wastes with a high content of
cellulose, ligno-cellulose, and hemi-cellulose, like spent grains, have a
high potential to become the key factor in cost-neutral brewery waste
discharge. Thus, the use of spent grains as an energy source by
anaerobic fermentation is a good solution. The key to solve this problem
is the combination of two well-known unit operations: milling and
fermentation. These application areas are focused on at the Chair of
Process Engineering of Disperse Systems. A current research project is
the biogas fermentation of spent grains in a multi-step solid-bed
process to optimize the dwell time. The spent grains are comminuted in a
stirred media mill to increase the specific surface area, resulting in a
higher degree of bioavailability, which is expected to have a positive
effect on degradation rate and hydraulic retention time. In order to
increase the energy utilization of the overall process, consisting of
grinding and fermentation, spent grains were pre-fermented in a
hydrolysis reactor preceding the grinding step. Thus, readily
biodegradable components such as proteins were dissolved, and there was,
therefore no need to grind them. This resulted in a decrease in
specific grinding energy. In the presented work, both non- and
pre-fermented spent grains were comminuted and compared regarding the
decrease of particle size depending on specific milling energy. Another
work package is to research in 2 L reactors, the maximum loading rate
for both fermentation steps. On the basis of the operating parameters of
the individual reactors steps, such as amount of gas, quality of gas,
pH value, redox potential, and fatty acids, the influence on loading
rate is shown in the fermentation process.
Benjamin Haeffner apprenticed as a specialist in food technology at
Döhler. He received a degree Dipl.-Ing. (M.S.) degree in food and
beverage technology from Technische Universität München-Weihenstephan,
Germany, in 2006. After that he started his career at the Chair of
Process Engineering of Disperse Systems at Technische Universität
München-Weihenstephan as a technical engineer in wet/dry-grinding and
fermentation processes. He is an expert in comminution of organic
materials and gives lectures in engineering science fundamentals of
apparatus. Since 2011 he has been working as a Ph.D. student at the
Chair for Process Technology of Disperse Systems and edited his own
project (“Biogas Fermentation in Multi-step Solid Bed Process as
Optimization for Dwell-Time”), which is supported by the German
Federation of Industrial Research Associations (AiF) and the Research
Group of the German Food Industry (FEI).
