EFFECTS OF GREEN LIQUOR PRETREATMENT ON THE ENZYMATIC HYDROLYSIS OF RICE STRAW

Rice straw (Oryza saliva L.) was cooked by green liquor (GL) as pretreatment for ethanol production at different Total Titratable Alkali (TTA) charges and temperatures. The effects of GL pretreatment on chemical composition and enzymatic saccharificaiton were investigated. Lignin can be effectively removed with the increase of temperature and TTA charge in GL pretreatment. Pretreatment under high GL charge and temperature obviously increases the sugar yield on the basis of pulp. However, sugar recovery drops when the GL temperature is over 140 C or TTA charge over 4% at high temperature due to the low pulp yield under a strong condition. After 48 h enzymatic hydrolysis under a cellulase loading of 40 FPU/g pulp, the total sugar yield of pulp pretreated by 4% GL at 140 C is the highest among all pretreated pulps. An enzymatic hydrolysis sugar conversion ratio over 75% could be achieved. The result indicates that GL pretreatment is an effective way to improve the enzymatic hydrolysis of rice straw.