Abstract:
Lignocellulosic biomasses are interesting feedstocks for ethanol production due to their abundance and renewability. But physico-chemical structural and compositional factors of them hinder the saccharification of cellulose in the lignocellulosic biomasses. Thus, the biomasses must be pretreated to enhance the enzymatic saccharification of cellulose. This research studied the pretreatment of lignocellulosic biomasses by autohydrolysis in batch and continuous plug-flow reactors. Feed in this work was rice straw mixed with cassava waste to make the slurry be continuously fed into the continuous reactor. In continuous pretreatment step, the effects of pretreatment temperatures (120 and 140 ˚C) and motor utility frequencies (5 and 10 Hz), relating to feed rate, were experimentally investigated. After the pretreatment, the entire pretreated sample was subjected to enzymatic saccharification by cellulase. The suitable conditions for enzymatic saccharification were also examined within the saccharification time of 0 144 hr and enzyme loading of 0 1,200 ul/1.2 g dry solid. It was found that the enzymatic saccharification is complete at 24 hr of saccharification time and 1,000 ul of enzyme loading/1.2 g dry solid. The results from continuous pretreatment revealed that the temperature is the most important factor on pretreatment efficiency. The overall glucose yield was increased when saccharified biomass pretreated at high temperature. When pretreatment temperature was 140 ˚C and motor utility frequency was 10 Hz, the overall glucose yield was increased approximately 2.5-fold and 1.5-fold over untreated rice straw and untreated slurry, respectively. On the other hand, further study about the effects of temperatures (120 - 200 ˚C) on pretreatment process in a batch reactor was performed. It was concluded that when considering both overall glucose yield and inhibitor formation, the optimum temperature to pretreat rice straw mixed with cassava waste was 160 ˚C, providing the overall glucose yield of 39.64%