Energy recovery from one- and two-stage anaerobic digestion of food waste

One- and two-stage anaerobic digestion of food waste aimed at recovering methane (CH4) and hydrogen and methane (H-2 + CH4), respectively, were compared in order to assess the potential benefits from the two-stage process in terms of overall energy recovery. Results suggest that a two-stage process where the first reactor is properly operated in order to achieve a significant net hydrogen production, may display a 20% comparatively higher energy recovery yield as a result, mainly, of enhanced methane production as well as of the associated hydrogen production. The highest methane production of the two-stage process was due to improved hydrolysis and fermentation of food waste, with increased amounts of volatile fatty acids being readily available to methanogenesis. (C) 2017 Elsevier Ltd. All rights reserved.