Impacts of Alkaline Hydrogen Peroxide Pretreatment on Chemical Composition and Biochemical Methane Potential of Agricultural Crop Stalks

Lignocellulosic stalks of three kinds of monocotyledonous (wheat, maize, and rice) and two kinds of dicotyledonous crops (rape and cotton) underwent 2% H2O2 pretreatment at pH 11.5 and 35 degrees C with 10% (w/v) biomass loading. Chemical composition analysis and biochemical methane potential (BMP) assays were carried out for biomass before and after pretreatment, in order to illuminate the impacts on bioenergy utilization efficiency caused by the alkaline hydrogen peroxide (AHP) pretreatment. The AHP pretreatment could recover about 90% of glucose and 80% of xylose, and remove around 50% and 30-40% of the lignin in monocotyledonous and dicotyledonous crop stalks, respectively. On the basis of volatile solid (VS) added into the pretreatment system, the observed BMP and digestible fraction of cotton stalk increased from 174 +/- 12 mL CH4/g VS to 216 +/- 6 mL CH4/g VS and from 36.0 to 44.7%, respectively. For the purpose of full utilization, the theoretical methane potentials of liquid waste generated from the AHP pretreatment were investigated. Theoretically, around 95 and 45 ml CH4/g VS from liquid wastes of monocotyledonous and dicotyledonous crop stalks could be produced, respectively. Besides, chemical compositional and structural changes showed that AHP pretreatment could break down esterified and etherified linkage in a lignocellulosic matrix.