title: Is the continuous two-stage anaerobic digestion process well suited for all substrates?
abstract: Two-stage anaerobic digestion systems are often considered to be advantageous compared to one-stage processes. Although process conditions and fermenter setups are well examined, overall substrate degradation in these systems is controversially discussed. Therefore, the aim of this study was to investigate how substrates with different fibre and sugar contents (hay/straw, maize silage, sugar beet) influence the degradation rate and methane production. Intermediates and gas compositions, as well as methane yields and VS-degradation degrees were recorded. The sugar beet substrate lead to a higher pH-value drop 5.67 in the acidification reactor, which resulted in a six time higher hydrogen production in comparison to the hay/straw substrate (pH-value drop 5.34). As the achieved yields in the two-stage system showed a difference of 70.6% for the hay/straw substrate, and only 7.8% for the sugar beet substrate. Therefore two-stage systems seem to be only recommendable for digesting sugar rich substrates.
authors.affiliation: University of Hohenheim, State Institute of Agricultural Engineering and Bioenergy, Garbenstraße 9, 70 599 Stuttgart, Germany. Electronic address: Jonas.Lindner@uni-hohenheim.de.
authors.forename: Jonas
authors.initials: J
authors.lastname: Lindner
authors.affiliation: University of Hohenheim, State Institute of Agricultural Engineering and Bioenergy, Garbenstraße 9, 70 599 Stuttgart, Germany.
authors.forename: Simon
authors.initials: S
authors.lastname: Zielonka
authors.affiliation: University of Hohenheim, State Institute of Agricultural Engineering and Bioenergy, Garbenstraße 9, 70 599 Stuttgart, Germany.
authors.forename: Hans
authors.initials: H
authors.lastname: Oechsner
authors.affiliation: University of Hohenheim, State Institute of Agricultural Engineering and Bioenergy, Garbenstraße 9, 70 599 Stuttgart, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Lemmer
mesh_terms: D000693:Anaerobiosis; D027461:Beta vulgaris / Q000737:chemistry*; D056804:Biofuels; D057919:Biological Oxygen Demand Analysis; D019149:Bioreactors; D004063:Digestion; D004867:Equipment Design; D005285:Fermentation; D005740:Gases; D006859:Hydrogen / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D008697:Methane / Q000737:chemistry*; D012820:Silage; D003313:Zea mays / Q000737:chemistry*
chemical_list: D056804:Biofuels; D005740:Gases; D006859:Hydrogen; D008697:Methane
keywords: Anaerobic digestion; Methane yield; Substrate; Two-stage; pH-control