CO-FERMENTATION OF BAGASSE AS WASTE OF THE ETHANOL INDUSTRY IN DIFFERENT MIXTURES AND PRETREATMENTS TO ENHANCE THE EFFICIENY OF THE ANAEROBIC DIGESTION

摘要

The production of sugarcane generates increasing amounts of waste as bagasse, vinasse and filter cake. The generation of biogas from sugarcane bagasse has a large energy potential. The sugarcane based bio-economy in Brazil is highly interested to increase their efficiency and to produce energy caused by increasing energy prizes. Other agro industry produces huge amounts of manure, which are currently more an environmental problem than a valuable biomass. The Co-Fermentation with bagasse or other by-products of the sugarcane industry has advantages for the specific biogas yield and the digestate quality. With the objective to evaluate the biogas production efficiency from the sugarcane industry and other waste, a search was conducted at the Technical Laboratory of the University Rostock, Germany together with guest scientist from the Federal University of Goias, Goiania in Brazil. The biogas tests are carried out according to the German directive VDI 4630 (VDI: German engineers association). Different mixtures of bagasse, vinasse filter cake with maize silage and variants with chemical pretreated bagasse (6%NaOH) were investigated. The co-fermentation of maize silage+bagasse (46-60%) results in a specific biogas yield of 500 to 556 l(N)/kgVS (OLR 2.2 kgVS/ m3 d). For maize silage + filter cake (50 to 80%) the highest specific biogas yield with 632 l(N)/kgVS was found for 50 filter cake at OLR 2.5 kgVS/ m3 d). The methane content of the biogas was nearly in all tests around 51%. The chemical pretreatment of bagasse increased the biogas production rate especially in the days 1 to 9. The surplus compared with the untreated bagasse was 11%. The supplement of trace elements and enzymes stabilized the biogas process.