Environmental Engineering Reference
In-Depth Information
Figure 6.3. Batch test equipment in heating cabinet.
The conclusion is that dry fermentation applications are able to reach high methane yields.
Nevertheless, there is still potential for optimization e.g. in terms of separation of disturbing
material, substrate intake into the fermenter and inoculation of fresh substrate being added to the
fermenter.
6.3.3
Results from waste digestion
Information about substrates is strongly demanded by biogas plant operators and future investors.
Targets of research work are therefore examining reachable degradation rates and methane yields
in mono-fermentation processes and co-fermentation processes of mixtures of different waste
fractions being representative for different regions in Europe. This chapter will present comparison
of process-relevant parameters of different single waste fractions and waste fraction mixtures
being assumed in laboratory scale batch tests and semi-continuous tests. For appraisal of the used
substrates, the following parameters have been acquired:
•
organic dry matter (oDM);
•
content of volatile fatty acids;
•
degradation of organic load in the fermentation process;
•
dry matter (DM) of substrate;
•
ortho-phosphate (PO
4
-P);
•
total nitrogen content (Kjeldahl-N);
•
ammonium nitrogen content (NH
4
-N).
The assessment of the continuous fermentation process is done with degradation rate of liquid
phase (concerning oDM, DM) (%):
•
degradation rate (amount of formed methane related to the results of the individual batch tests);
methane productivity (m
3
methane/m
3
fermenter volume);
•
methane yield in (m
3
methane/kg oDM);
•
•
reached biogas quality.
Figure 6.3 shows the batch tests with a volume of 3.5 liters being operated according to German
VDI 4630 (VDI 2008) and Table 6.3 shows the process-relevant results from lab scale batch test
analysis.
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