Effect of ozone pretreatment of flax fiber processing waste under less water environment: Physicochemical property evaluation and digestibility metrics

Compared with the commonly used pretreatment such as organosolv, diluted acid/alkali, etc., gas phase pretreatment got the advantages of low water consumption, low reaction temperature/ time, and could degraded cellulose to smaller chains without much cellulose loss. Thus, this study pretreated flax fiber manufacturing processing waste (FFPW) with gas phase ozone for producing fermentable sugar. Experimental results showed that FFPW got about 32.5% lower lignin (13.0%) and 59.0% higher cellulose/hemicellulose ratio (3.66) compared with most of the commonly used lignocellulose materials; which make it suitable for fermentable sugar production. Gas phase pretreatment got 31.9% higher delignification rate than that under liquid phase. Under the optimal reaction condition (extra water content 79.7%, pH 3.2, ozone feed speed 101.4 mg/L/min, 21.8 min, room temperature), the FFPW get lignin content of 3.6%, cellulose content of 73.8%, digestibility of 96.1% (solid concentration 0.02 g/mL). Under high solid concentration hydrolysis (solid concentration 0.4 g/mL), ozone pretreated FFPW released 168.0 g/L glucose, which was about 10.0% higher than that of the commonly used lignocellulose materials.