Laboratory investigations on co-digestion of energy crops and crop residues with cow manure for methane production: Effect of crop to manure ratio

A. Lehtomäki, S. Huttunen and J.A. Rintala

Resources, Conservation & Recycling, 2007, vol. 51, issue 3, 591-609

Abstract: Anaerobic co-digestion of grass silage, sugar beet tops and oat straw with cow manure was evaluated in semi-continuously fed laboratory continuously stirred tank reactors (CSTRs). Co-digestion of manure and crops was shown to be feasible with feedstock volatile solids (VS) containing up to 40% of crops. The highest specific methane yields of 268, 229 and 213lCH4kg−1VSadded in co-digestion of cow manure with grass, sugar beet tops and straw, respectively, were obtained with 30% of crop in the feedstock, corresponding to 85–105% of the methane potential in the substrates as determined by batch assays. Including 30% of crop in the feedstock increased methane production per digester volume by 16–65% above that obtained from digestion of manure alone. Increasing the proportion of crops further to 40% decreased the specific methane yields by 4–12%, while doubling the loading rate from 2 to 4kg VSm−3day−1 decreased the specific methane yields by 16–26%. The post-methanation potential of the digestates corresponded to 0.9–2.5m3CH4t−1 wet weight of digestate and up to 12–31% of total methane production in northern climatic conditions, being highest after co-digestion of manure with straw.

Keywords: Anaerobic digestion; Biogas; Co-digestion; Cow manure; Crop residues; CSTR; Energy crops; Energy crop digestion testing; Methane potential; Methane production (search for similar items in EconPapers)
Date: 2007
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Citations: View citations in EconPapers (9)

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Persistent link: https://EconPapers.repec.org/RePEc:eee:recore:v:51:y:2007:i:3:p:591-609

DOI: 10.1016/j.resconrec.2006.11.004

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