In a full scale anaerobic digestion plant exclusively operating on solid energy crops the mass-flows were analysed for two different substrate compositions over 583 d. The mono-fermentation of maize whole crop silage was compared to a mixture of maize and grass + clover silage. The two stage system required the input of dilution liquid guarantee digestion and agitation in the high loaded first stage (OLR: 5.50 kgVS·m−3·d−1). Grass + clover demanded the double mass of process dilution liquid, which reduced SRT from 65 d to 34 d for each stage and leaded to an increased generation of Solid Digestion Residues by separation. Experiments showed that 70% of the Residual Methane Potential are caused by the 7% mass fraction of SDR. For maize and maize + grass + clover RMPs of 6.34% and 11.80% were observed, respectively. RMP can also be expressed as additional substrate input required for full granted operation. Thus, the mass stream analysis is used to determine mitigation strategies for RMP.
The influence of energy crop substrates on the mass-flow analysis and the residual methane potential at a rural anaerobic digestion plant
C. Resch, R. Braun, R. Kirchmayr; The influence of energy crop substrates on the mass-flow analysis and the residual methane potential at a rural anaerobic digestion plant. Water Sci Technol 1 January 2008; 57 (1): 73–81. doi: https://doi.org/10.2166/wst.2008.733
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