COMPONENTS SEPARATION AND SACCHARIFICATION OF WHEAT STRAW BY SULFITE PRETREATMENT (SPORL)

摘要

An orthogonal designed SPORL process was adopted to investigate the effects of the sulfite pretreatment on the components separation and saccharification of wheat straw. The SPORL process was composed of sulfite pretreatment under acidic condition followed by mechanical size reduction using high consistency refiner. Reaction temperature, retention time and charge of sodium bisulfite and sulphuric acid were considered as main factors. The results showed that all the four factors had impact on the saccharification of wheat straw. Raising the temperature, increasing the charge of sodium bisulfite or sulphuric acid, and extending retention time would improve the dissolution of pentosan and lignin and the saccharification efficiency, while causing the further conversion of pentose. The separation of lignin and pentosan from wheat straw was the main cause of the limited saccharification. With enzyme loading of cellulase 5 FPU plus β-glucosidase 4 CBU per gram of o.d. substrate, glucose yield 72.45% was achieved using the substrate pretreated under the condition of temperature 180°C, sodium bisulfite charge 3%, sulfuric acid charge 1.48% and retention time 20min. Separating cellulose, lignin and hemicellulose from the low-priced and abundant wheat straw on the basis of mature sulfite pulping and disk refining technology, the sulfite pretreatment has very few barriers and risks for commercialization.