Ozone pretreatment of sugi sawdust for enzymatic saccharification- ethanol fermentation

摘要

In order to utilize lignocellulosic biomass as a raw material of bioethanol, ozone pretreatment was conducted on Japanese cedar (sugi) sawdust and the enzymatic susceptibility was evaluated. On treating the sawdust with ozone, it was found that the moisture content of the sample greatly affects the efficiency of ozone consumption. By adjusting the moisture content to proper amount, it became possible to conduct ozone pretreatment extendedly and the yield of reducing sugars obtained after enzymatic saccharification rose to c.a. 80% in ozonation, while untreated sample yielded only 2.5%. At the same time, the total yield of nitrobenzene oxidation products, which was determined as an indicator of degradation of lignin, decreased to nearly zero after ozonation. Trials to decrease ozone dosage by changing ozone flow rate or ozone concentration, or lowering pretreatment temperature were unsuccessful so far. Reduction of particle size of the sample did increase the sugar yield when dried sample was used. But when never-dried wet sample was used, a decrease caused by drying and an increase caused by milling were cancelled with each other. A calorific value of the saccharification residues was determined. They decreased only slightly by the progress of the ozone pretreatment.