Anaerobic fermentation characteristic of green corn straw pretreated by steam explosion

The anaerobic fermentation characteristic of green corn straw pretreated by steam explosion method was studied. The steam explosion pressure and during time were 2.5 MPa and 90 s. The fermentaion experiments were carried out with 30% (mass percentage) of the biogas slurry. The TS (total solid mass) mass percentages of the steam-exploded straw were 1%, 2%, 3%, 4%, 6%, 8%, 10% respectively, and 15% and that of the green straw without pretreatment was 6%. The pH value, CH4 volume percentage and biogas yield were measured each day. The results showed that, when the TS mass percent was high, the anaerobic fermentation liquid of steam-exploded straw was easily acidificated and the appropriate TS mass percentage was not more than 4%, while fermentation of the unexploded straw could be carried out well under TS mass percentage of 6%. The biogas yield of volatile solid of unexploded straw was 214.6 mL/g, while that of the exploded straw had the maximum value of 334.8 mL/g under the TS mass percentage of 3%. The biogas production rate of volatile solid of unexploded straw was 3.3 mL/g each day, while that of the exploded straw decreased with the increasing of the TS mass percentage and had the maximum value of 14.8 mL/g each day under the TS mass percentage of 1%. The biogas yield and production rate of the exploded straw were improved obviously and the fermentation period was shortened greatly. The research can provide a reference for the straw energy utilization in industrial production.