Lime pretreatment of crop residues bagasse and wheat straw

• Published in: Applied biochemistry and biotechnology Vol. 74; no. 3; pp. 135 - 159
• Main Authors: Chang, V.S. (Texas AandM University, College Station, TX.), Nagwani, M, Holtzapple, M.T
• Format: Journal Article
• Language: English
• Published: Heidelberg Springer 01.09.1998; Springer Nature B.V
• Subjects: Alkalies; BAGASSE; BAGAZO; Biochemistry; Biofuel production; Biological and medical sciences; Biomass; Biotechnology; CALCIUM HYDROXIDE; Carbon dioxide; Carbonation; CELLULASE; CELULASA; CROP RESIDUES; Crop yield; Digestibility; Energy; Enzymes; Fundamental and applied biological sciences. Psychology; Glucan; Glucose; HIDROLISIS; HIDROXIDO DE CALCIO; High temperature; HYDROLYSE; HYDROLYSIS; HYDROXYDE DE CALCIUM; Industrial applications and implications. Economical aspects; Lime; Low temperature; Material balance; PAILLE DE BLE; PAJA DE TRIGO; Pretreatment; RESIDU DE RECOLTE; Residues; RESIDUOS DE COSECHAS; SACCHARIFICATION; Slaked lime; Straw; Studies; Sugar; Triticum aestivum; Wash water; Wheat; WHEAT STRAW; Xylan; Enzyme; Biofuel; Lignocellulosics; Glucose; Recovery; Optimization; Sugar cane(by product); Lime; Cellulase; Glycosidases; Production; Hydrolases; Pretreatment; O-Glycosidases
• ISSN: 0273-2289; 1559-0291
• DOI: 10.1007/bf02825962

Lime (calcium hydroxide) was used as a pretreatment agent to enhance the enzymatic digestibility of two common crop residues: bagasse and wheat straw. A systematic study of pretreatment conditions suggested that for short pretreatment times (1-3 h), high temperatures (85-135 degrees C) were required to achieve high sugar yields, whereas for long pretreatment times (e.g., 24 h), low temperatures (50-65 degrees C) were effective. The recommended lime loading is 0.1 g Ca(OH)2/g dry biomass. Water loading had little effect on the digestibility. Under the recommended conditions, the 3-d reducing sugar yield of the pretreated bagasse increased from 153 to 659 mg Eq glucose/g dry biomass, and that of the pretreated wheat straw increased from 65 to 650 mg Eq glucose/g dry biomass. A material balance study on bagasse showed that the biomass yield after lime pretreatment is 93.6%. No glucan or xylan was removed from bagasse by the pretreatment, whereas 14% of lignin became solubilized. A lime recovery study showed that 86% of added calcium was removed from the pretreated bagasse by ten washings and could be recovered by carbonating the wash water with CO2 at pH 9.5