BayFORREST

BAVARIAN RESEARCH ASSOCIATION FOR WASTE MANAGEMENT AND RECYCLING RESEARCH

F213 Accelerated anaerobic hydrolysis of organic structural materials for the production of usable products

Field of work:

Ruminant animals, like cattle, sheep and goats, eat lignocellulosic material including grass and leaves and sometimes paper and cardboard. They liquefy these materials in their special digesting system within a few hours, so that it can be used for further utilization. Ruminants use certain micro organisms to breakdown the cellulose contained in their food to simple compounds to derive energy. Microbiological research has shown that this fast transformation of solid materials into utilizable compounds is achieved by a partnership from Fungi, Bacteria, Protozoa and Archaea. The main component of human garbage is cellulose material. Presently, conventional solid waste treatment procedures require up to 4 to 6 weeks for this process-limiting hydrolysis step. It is proposed to model a new system on the rumen to improve performance and reduce costs.

Issues of future research:
The organic material which is to be treated is initially cut up by a grinder and mixed with a special buffer solution and treated wastewater to form a slurry. This is transported to a reactor, which contains microorganisms from the Rumen where the feed material is hydrolyzed. In addition the reactor temperature, pH and mixing must be similar to the natural rumen. As with the ruminants, the material is internally recirculated over a wet milling device facilitating further size reduction. Subsequently, the liquefied material is pumped to a biogas reactor where fermentation gas is produced. The methane gas produced can be used for generating electricity or heating.

Application:
Conventional fermentation procedures which are in practice, in this the new technique possesses substantial advantages. Material residence time is reduced from weeks to hours enabling substantially smaller and thus cheaper systems. In addition to this, a higher extent of degradation and a therefore higher fermentation gas yield can be achieve, which will allow improved sustainability in systems for the future.