Comparison of the physical-chemical properties of corn stalk by expansion and chemical pretreatments and their effect on the yield of biogas

The physical-chemical properties of corn stalk were comparatively investigated after 1% of sulfuric acid, 2% of sodium hydroxide and expansion pretreatments, and then their effect on producing biogas of the treated corn stalk were assessed. Three physical-chemical indicators including the reducing sugar yield, the organic components and the microstructures revealed by scanning electron microscopy were detected in this study. The results showed that the conversion rate of the reducing sugar of corn stalk treated with 1% of sulfuric acid was the highest (17.8%), the startup speed of anaerobic zymolysis of corn stalk treated with 2% of sodium hydroxide was the fastest, and the total effect on producing biogas of corn stalk treated with expansion method was the best. The daily gas production rate of corn stalk after expansion pretreatment reached 0.63 m3·m-3·d-1, the 60d total gas production rate reached 5.89 m3·m-3, and the methane content come up to 82.9%. The results obtained in this paper provide a new and effective method to improve by a large amount the biogas yield of corn stalk.