Utilization of Sago Solid Waste for Bioethanol Production With Variation of Sago Solid Waste-Solvent Ratio and Pre-treatment Time

Abstract

Sago solid waste is a lignocellulosic material that can be used as a raw material for making bioethanol. The lignin component of lignocellulose can slow saccharification by preventing cellulase enzymes from accessing cellulose. The pre-treatment stage is the first stage of the lignocellulose-to-bioethanol conversion process, and it is used to lower lignin levels in lignocellulose. Saccharification and fermentation are the next processes in turning lignocellulosic material to bioethanol. The pre-treatment stage was carried out in this study using a 10% NaOH solution at a 4 bar pressure reactor and a temperature of 140 °C, while the saccharification and fermentation stages were carried out simultaneously (SSF) using cellulase enzymes and yeast Saccharomyces cerevisiae at 30 °C and pH 5. The ratio of sago solid waste to NaOH solution and the period of the pre-treatment process were varied in the study. The sago solid waste to solvent ratios were 1:5, 1:6, and 1:7, with processing times beginning at 20 minutes, 30 minutes, and 40 minutes. The maximum lignin reduction results (60.11%) were obtained at a ratio of 1:7 and a pre-treatment time of 40 minutes, while the highest yield of sago solid waste mass (35.14%) was obtained at a ratio of 1:5 and a pre-treatment process duration of 20 minutes. The results of the initial treatment stage were then continued with SSF for 0 hours, 24 hours, 48 hours, and 72 hours with the highest bioethanol content of 12% at 72 hours.