Co-digestion of molasses with dry grain sweeps and birch leaves

Abstract

Support for biogas production in Latvia has decreased. There is an urgent need to investigate the suitability of various inexpensive renewable biomass resources for energy production. Also, it is necessary to explore the possibilities to improve the anaerobic digestion process with the help of various catalysts. Molasses is a good raw material for co-digestion with biomass having low biodegradability. The article shows the results of studies on biogas (methane) production from dry grain sweeps, birch leaves and from their co-digestion with molasses. The anaerobic digestion process was performed in 0.75 l laboratory digesters, operated in batch mode (38 ± 1.0, 32 days). The average specific biogas or methane production per unit of dry organic matter added (DOM) from molasses was 0.840 l·g-1DOM or 0.457 l·g-1DOM respectively. Average specific biogas or methane volume produced from dry grain sweeps (residues) in anaerobic fermentation was 0.777 l·g-1DOM or 0.402 l·g-1DOM respectively. Average biogas or methane yield from co-digestion of dry grain sweeps and molasses was 0.772 l·g-1DOMor 0.433 l·g-1DOM respectively. Average specific biogas or methane yield from anaerobic fermentation of birch leaves and molasses was 0.737 l·g-1DOM or 0.369 l·g-1DOM respectively. All investigated biomass resources can be used for methane production.