Effects of Pyrolysis on Biogas Production during Anaerobic Co-digestion of Corn Stover

¹ Graduate School of Agriculture, Hokkaido University, 9-9 Kita, Kita-ku, Sapporo, Hokkaido 060-8589, Japan
² Research Faculty of Agriculture, Hokkaido University, 9-9 Kita, Kita-ku, Sapporo, Hokkaido 060-8589, Japan

^* Corresponding author: shimizu@bpe.agr.hokudai.ac.jp

Abstract

The effects of pyrolysis pretreatment on biogas production during anaerobic co-digestion of corn stover were studied. The corn stover characteristics were investigated by performing thermogravimetric analysis using a heating rate of 10.0°C/min and an air atmosphere at atmospheric pressure. Corn stover aliquots pretreated in an electric furnace at 100°C for 360 min, 200°C for 15 min, and 300°C for 5 min were used. Untreated and pretreated corn stover samples were analyzed by scanning electron microscopy and other methods, and the bulk densities and component ratios were compared to identify changes caused by the pretreatments. The amounts of total solids, volatile solids, volatile fatty acids, and total ammonia nitrogen produced when the stover samples were anaerobically digested were measured. The biogas production rate and the methane concentration in the biogas were determined. The substrate-specific methane yields were determined, and the relationships between the yields and pretreatment conditions were assessed. The sample pretreated at 300°C for 5 min produced the most biogas. The corn stover total solid bulk density was directly related to the substrate-specific methane yield, the substratespecific methane yield decreasing as the total solid bulk density increased.