Microwave-Irradiation of Lignocellulosic Materials Xt Conversion of Microwave-Irradiated Agricultural Wastes into Ethanol

Abstract--Agricultural wastes, including rice straw, rice hulls and sugar cane bagasse, pretreated by a continuous microwave-irradiation were converted into ethanol. Almost all hemicelluloses were autohydrolyzed during the pretreatment at 21O-220°C. Addition of acetic acid (0.5 % concentration) into irradiation medium permitted lower-ing temperature by 10 to 30°C. Most of cellulose in pretreated samples of rice straw and bagasse was more effectively digested by cellulases because of the increase in their enzymatic susceptibility. Removal of hemicelluloses had, however, no direct connection with the increase of digestibility. Glucose produced by enzymatic saccharification were completely converted into ethanol. Yields of ethanol produced per kilogram (dry weight) of the pretreated samples of rice straw and bagasse were 378 ml and 285 ml, respectively. Since the sever conditions of pretreatment to increase the enzymatic susceptibility reqiured the considerable amount of electric power, the milder condition to reduce the energy consumption for ethanol production was determined in this report. Key words: continuous microwave-irradiation, r~moval of hemicelluloses, enzymatic digestibility, ethanol production, energy consumption 1