<![CDATA[Oil Palm Empty Fruit Bunches (OPEFB) are abundant lignocellulosic waste with great potential as a substrate for bioethanol production. One approach to improve fermentation efficiency is through the use of immobilized cells, where microbial cells are entrapped within a Na-alginate matrix to enhance stability and enable repeated use. This study aimed to determine the effect of cell concentration and Na-alginate concentration on the production of immobilized cells for bioethanol production from OPEFB and to identify the optimal combination that yields the highest ethanol concentration. This research employed a Factorial Randomized Block Design (RBD) with two factors: cell concentration (OD 20, 30, and 40) and Na-alginate concentration (3%, 4%, and 5% (b/v)). Fermentation was carried out using the Separate Hydrolysis and Fermentation (SHF) method for 96 hours at 35°C. Observed parameters included pH, total dissolved solids (TDS), reducing sugar content, and ethanol content. The results showed that cell concentration and Na-alginate concentration significantly influenced pH, total dissolved solids, reducing sugar content, and ethanol concentration. The best combination was found at a cell concentration of OD 30 and a Na-alginate concentration of 4%, resulting in the highest ethanol content of 3,26 ± 0,276 % v/v, final pH of 4,37 ± 0,035, total dissolved solids of 5,6 ± 0,283 oBrix, and reducing sugar content of 0,22 ± 0,009 g/L. The use of immobilized cells with optimized cell and Na-alginate concentrations proved effective in enhancing fermentation process and bioethanol productivity from OPEFB. ]]>
