 Why does mono-digestion of grass silage fail in long term operation?T. Thamsiriroj, A.S. Nizami and J.D. Murphy Applied Energy, 2012, vol. 95, issue C, 64-76 Abstract: This paper presents modelling based on 340days of operation of a small pilot-scale, 2-stage completely-mixed digester, loaded gradually up to an organic loading rate of 2.5kgm−3d−1. The reactor suffered mechanical failure in the agitation system due to high solids content in the digester. This was preceded by a 20% fall in methane production (from 455 to 363LCH4kg−1VS added) when the loading rate was increased from 2 to 2.5kgVSm−3d−1. The system was modelled using the ADM1 model which could not correctly simulate total VFA and pH in the digester system. Lactic acid is a significant element of grass silage (73% of total acids). This paper modified ADM1 through assessment of lactic acid; the results allowed close fit to experimental data. The simulation suggested that inhibition of acetogenesis initiated failure, leading to accumulation of lactic acid, reduction of acetic acid (substrate for aceticlastic methanogens), a drop in pH, less methane production, less destruction of solids, increased dry solids content and eventually failure of the mechanical agitator. Keywords: Grass silage; Mono-digestion; Anaerobic digestion; Modelling; ADM1 (search for similar items in EconPapers) Downloads: (external link) Related works: Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text Persistent link: https://EconPapers.repec.org/RePEc:eee:appene:v:95:y:2012:i:c:p:64-76 Ordering information: This journal article can be ordered from DOI: 10.1016/j.apenergy.2012.02.008 Access Statistics for this article Applied Energy is currently edited by J. Yan More articles in Applied Energy from Elsevier |
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