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BioMed Research International
Volume 2014, Article ID 712197, 8 pages
http://dx.doi.org/10.1155/2014/712197
Research Article

Effects of Psychrophilic Storage on Manures as Substrate for Anaerobic Digestion

Department of Process, Energy and Environmental Technology, Telemark University College, 3918 Porsgrunn, Norway

Received 6 May 2014; Revised 19 June 2014; Accepted 24 June 2014; Published 5 August 2014

Academic Editor: Ilona Sárvári Horváth

Copyright © 2014 Wenche Bergland et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The idea that storage can enhance manure quality as substrate for anaerobic digestion (AD) to recover more methane is evaluated by studying storage time and temperature effects on manure composition. Volatile fatty acids (VFA) and total dissolved organics (CODs) were measured in full scale pig manure storage for a year and in multiple flasks at fixed temperatures, mainly relevant for colder climates. The CODs generation, influenced by the source of the pig manure, was highest initially (0.3 g COD L−1d−1) gradually dropping for 3 months towards a level of COD loss by methane production at 15°C. Methane emission was low (<0.01 g COD L−1d−1) after a brief initial peak. Significant CODs generation was obtained during the warmer season (T > 10°C) in the full scale storage and almost no generation at lower temperatures (4–6°C). CODs consisted mainly of VFA, especially acetate. All VFAs were present at almost constant ratios. The naturally separated manure middle layer without sediment and coarser particles is suitable for sludge bed AD and improved further during an optimal storage time of 1–3 month(s). This implies that high rate AD can be integrated with regular manure slurry handling systems to obtain efficient biogas generation.