ENZYMATIC HYDROLYSIS OF PULP FROM WHEAT STRAW FOR BIOETHANOL PRODUCTION

With the depletion of oil resources, bioethanol is regarded as a promising biofuel substitute for gasoline. As a result of its substantial agricultural growth, wheat straw is an important alternative raw material to grain crops that are currently used for fuel ethanol production in China. For this study, an ethanol pulping process using sulfuric acid as a catalytic agent has been evaluated for bioconversion of wheat straw to glucose. The concentration of the glucose was measured after the enzymatic hydrolysis of the cellulose. Enzyme dosage, pH value, pulp concentration, time and temperature of enzymatic hydrolysis were investigated, and each factor was designed at four levels. Measuring the content of glucose, the optimal conditions were found by an orthogonal experiment. Approximately 89.76% of the total cellulose was recovered as monomeric glucose under optimal conditions. Then the fed-batch enzymatic hydrolysis was studied. With the extension of time, the concentration of substrate was gradually increased. At the same time, an appropriate amount of cellulase was added. The hydrolysis reaction was suspended until the glucose concentration will not significantly rise. Approximately 96.53% of the total cellulose was recovered as monomeric glucose under optimal conditions. In conclusion, compared with batch enzymatic hydrolysis, fed-batch enzymatic hydrolysis is an effective method to increase the hydrolysis yield and the hydrolysis yield increased by 6.77%.