Title: Effect of various leachate recirculation strategies on batch anaerobic digestion of solid substrates

Authors: Sigrid Kusch; Hans Oechsner; Thomas Jungbluth

Addresses: Institute of Waste Management and Contaminated Site Treatment, Technical University of Dresden, Pratzschwitzer Strasse 15, 01796 Pirna, Germany; Institute for Agricultural Engineering, University of Hohenheim, Garbenstrasse 9, 70599 Stuttgart, Germany; Institute for Sanitary Engineering, Water Quality and Solid Waste Management, University of Stuttgart, Bandtaele 2, 70569 Stuttgart, Germany. ' State Institute of Agricultural Engineering and Bioenergy, University of Hohenheim, Garbenstrasse 9, 70599 Stuttgart, Germany. ' Institute for Agricultural Engineering, University of Hohenheim, Garbenstrasse 9, 70599 Stuttgart, Germany

Abstract: Various leachate recirculation strategies were applied to a batch-wise operated solid-phase digestion system in laboratory-scale tests. Comparative experiments with both continuous and intermittent leachate recirculation revealed no advantages of a continuous flow. Results suggest that leachate recirculation should not be carried out continuously during process initialisation when methanogenesis is the rate-limiting step. Continuous watering resulted in the accumulation of Volatile Fatty Acids (VFA) during process start-up. In addition, no need for continuous water circulation was found for the following digestion process when hydrolysis was rate-limiting. Even in the absence of liquid recirculation, degradation was only slightly retarded when the biomass moisture content was adjusted.

Keywords: biogas; dry digestion; leachate recirculation; one-stage systems; batch process; batch anaerobic digestion; solid substrates; volatile fatty acids; water circulation; hydrolysis; biomass moisture content.

DOI: 10.1504/IJEWM.2012.044161

International Journal of Environment and Waste Management, 2012 Vol.9 No.1/2, pp.69 - 88

Published online: 13 Dec 2014 *

Full-text access for editors Full-text access for subscribers Purchase this article Comment on this article