Comparison of Alkali and Biological Pretreatment Methods for Elephant Grass (Pennisetum purpureum Scumach.) to Reduce Lignin Content in the Bioethanol Production Process

• Main Author: Obert Delimanto (Nim : 11214035), Wendo
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/31573
• Institution: Institut Teknologi Bandung

Elephant grass is one of lignocellulosic plants which has the potential to be converted as <br /> <br /> bioethanol due to high productivity and relatively fast harvesting time. However, the <br /> <br /> problems of lignocellulosic plants to be processed into bioethanol are the high lignin <br /> <br /> content and the different lignin structure of each plant. Lignin can inhibit the access of <br /> <br /> cellulose and hemicellulose by biological agents to be processed into bioethanol. Therefore, <br /> <br /> it is necessary to select and optimize the pretreatment process with the aim of degrading <br /> <br /> lignin and maintaining the value of the cellulose. This study was conducted with the aim to <br /> <br /> compare between biological pretreatment and alkaline pretreatment which one is more <br /> <br /> optimal in degrading lignin. Lime (Ca(OH)2) with a concentration of 0.05, 0.1, and 0.5 <br /> <br /> grams/gram of substrate was added to the elephant grass substrate with a size of about 2 <br /> <br /> mm, incubated at 23-25 oC with a variation of time 6 , 24, and 96 hours. Biological <br /> <br /> pretreatment agents using Aspergillus niger were incubated with variations in <br /> <br /> concentrations of 106, 107, and 108 cells/mL on the elephant grass substrate with optimal <br /> <br /> temperature of 35oC and variations in time 1, 3, 5, 7, and 9 days. Another biological <br /> <br /> pretreatment agent using Phanerochaete chrysosporium was also incubated with optimal <br /> <br /> conditions and used as a comparison for the Aspergillus niger with a concentration of 106 <br /> <br /> with a temperature of 35oC for 28 days. After that, the extracted elephant grass was tested <br /> <br /> for lignocellulose content, included hot water soluble, Hemicellulose, cellulose, lignin, and <br /> <br /> ash, using chesson datta method and reducing sugar test. Comparison of biological <br /> <br /> pretreatment between Aspergillus niger and Phanerochaete chrysosporium showed that <br /> <br /> Aspergillus niger was better at degrading lignin with ratio lignin to cellulose parameters <br /> <br /> 24.3% smaller than Phanerochaete chrysosporium at 30,645%. Then, biological <br /> <br /> pretreatment using Aspergillus niger compared with Alkali pretreatment (Ca(OH)2) <br /> <br /> obtained results that biological pretreatment with Aspergillus niger is more optimal with the <br /> <br /> main parameters, the ratio of lignin to cellulose.