Untersuchungen zur zweiphasigen Vergärung von Grassilage

Publication Type

Doctoral thesis

Authors

Simon Zielonka

Year of publication

2013

Pubisher

Shaker , Aachen

Series/labeling

Forschungsbericht Agrartechnik

ISBN / ISSN / eISSN

978-3-8440-1819-6

Page (from - to)

154

The anaerobic digestion of grass silage as a single substrate, which is a problematic substrate in CSTR digesters, was researched at the State Institute of Agricultural Engineering and Bioenergy at the University of Hohenheim. Lab research was conducted at a two-phase biogas plant consisting of a leach bed reactor and an anaerobic filter. The research goal was to identify and to optimize relevant process parameters, to be able to judge if this biogas process is a possible alternative to biogas processes that are in use in praxis. At the test biogas plant, which consists of five pairs of reactors, we observed the effects of the varied parameters on the methane yield and its distribution to the two phases, the degree of degradation and the amount of leached COD from the leach bed reactor. The results show that the separation of the phases could be improved by frequent exchange of the leachate. The research into the leach bed reactor temperature shows that the fastest and highest methane production of the two-phase biogas plant occurs at a temperature of 55°C. The use of different substrates result in individual digestion characteristics that majorly affect the quality of the phase separation. In total, a stable digestion process was observed in all experiments, and at optimal parameters of the test plant, methane yields comparable to one phase reference systems were reached. However, the retention time of one kilogram of organic dry matter was only 25 days. The experiments showed the efficiency of the discontinuous two-phase anaerobic digestion process with a leach bed reactor and an anaerobic filter. Relevant aspects for the operation and the optimisation of the process were discovered.