The production of methane from the straw pellets with addition of enzymes
Latvia University of Life Sciences and Technologies, Faculty of Engineering, Institute of Energetics, Cakstes blvd. 5, LV3001, Jelgava, Latvia
Biogas production requires much cheaper raw materials. The use of straw, as not always the full use of agricultural residues, increases the methane yield in pelletised form compared to non-pelletised straw. Lack is the high ratio of carbon to nitrogen content of straw, which leads to a slow and incomplete breakdown of the matter, and less producing substances from which bacteria produce methane.Variety of additives can be used to improve anaerobic digestion process. This article shows the results of the study, where the enzymes alpha amylase and xylanase and catalysts Metaferm and Melafen mixture are used for the digestion process echancement. Investigation was provided in 16 bioreactors operated in batch mode at 38 °C. Additives were filled into 14 bioreactors and only inoculum were filled into two bioreactors for control. The yield of biogas from straw pellets without additives was 0.655 L g-1DOM and methane 0.301 L g-1DOM after 34 days of anaerobic digestion. The yield of biogas from straw pellets with added alpha amylase was 0.652 L g-1DOM and methane 0.318 L g-1DOM. The yield of biogas from straw pellets with added xylanase was 0.689 L g-1DOM and methane 0.347 L g-1DOM. The yield of biogas from straw pellets with added Metaferm and Melafen mixture was 0.638 L g-1DOM and methane 0.254 L g-1DOM. The study demonstrates that the adding of enzymes increases the production of methane.