Joni Prasetyo, Moh Adrian Barra Akbar, Aulanni’am, Euis Filailla, Deliana Dahnum, Roni Maryana, Muryanto Muryanto, Eka Triwahyuni, Yanni Sudiyani, Teuku Beuna Bardant, Yan Irawan, Hirofumi Hirai
To participate in the Indonesian government program related to the renewable energy mix, research was carried out on the development of bio-ethanol technology from oil palm empty fruit bunch (EFB). The availability of TKKS is abundant in line with the amount of crude palm oil (CPO) production in Indonesia as the biggest producer. As a continuation of environmentally friendly EFB delignification, the delignified EFB can be utilized as bio-ethanol raw materials. This work was carried out using technical grade cellulase to reduce production costs. Optimizing bio-ethanol production from delignified EFB was started by minimizing nutrients, yeast extract (YE), and peptone. The next stage was to optimize bioethanol production for various amounts of delignified EFB and cellulase concentrations with simultaneous saccharification and fermentation (SSF). The SSF was converted biologically to bio-ethanol by setting two parameters. EFB amount was varied: 100 g treated EFB L−1, 125 g treated EFB L−1, 150 g treated EFB L−1, and 175 g treated EFB L−1 and cellulase at 9 FPU/g-EFB, 12 FPU/g-EFB, 15 FPU/g-EFB, and 18 FPU/g-EFB. When delignified EFB was too dense in the medium, it caused poor mixing, thereby reducing the bio-ethanol produced. Bio-ethanol reached only 11.87 g L−1 at 150 g-EFB L−1 and 18 filter paper units (FPU) g-EFB−1. Crude bio-ethanol 40 g L−1 was reached by fed-batch SSF and required 250 g-EFB L−1 and 60 FPU g-EFB−1. Cell growth metabolism was considered, leading to low biomass conversion to bio-ethanol per consumed carbon source. The pace of enzymatic hydrolysis to form sugar was compared with the growth of S. cerevisiae. Therefore, a lot of cellulase was required to achieve ethanol production of 40 g L−1. Modified SSF was set to minimize cellulase by enzymatic hydrolysis at cellulase optimum condition for 24 h and SSF with S. cerevisiae for 48 h. This method was able to reduce the use of cellulase to 30 FPU g-EFB−1 and 250 g-EFB L−1, and the bio-ethanol reached 41 g L−1. High-performance liquid chromatography (HPLC) analysis showed that the remaining disaccharides at the end of SSF were very high. Additional lactase was added with a ratio of 1:4 of cellulase. Based on the scanning electron microscope (SEM) and energy dispersive X-ray spectrometer (EDS) observation, the remaining EFB fiber can be re-used for bio-ethanol production because of similar components with delignified EFB for lignin and holocellulose. Bio-ethanol fuel grade was obtained after distillation and dehydration with a molecular sieve and fulfilled the requirement of fuel grade with research octane number (RON) reaching 100. Therefore, bio-ethanol also contributes to increasing the octane number of gasoline. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2024.
Research Center for Chemistry, National Research and Innovation Agency, KST BJ Habibie, Building 452, South Tangerang, Serpong, Indonesia; Chemical Engineering, Pamulang University, South Tangerang, Indonesia; Chemistry Department, Brawijaya University, Malang, East Java, Indonesia; Faculty of Agriculture, Shizuoka University, Shizuoka, Japan
