Production of ethanol from oil palm trunk by simultaneous saccharification and fermentation process at bench scale

Abstract

A largenumber of oil palm trees are replanted every year. Considering the extent of replanting and OPT's high starch and sugar content, it was determined to be a potential raw material for bioethanol production. This study conducted ethanol production by simultaneous saccharification and fermentation of starch-rich powder extracted from oil palm trunks. Fermentation was conducted on a 100 L bench scale to evaluate the feasibility and further development of the process before the process is implemented at a larger scale. The preparation of the starch-rich flour involves shredding, drying, and screening of the trunks until the starch-rich powder passes through an 80-mesh sieve. Furthermore, starch was liquefied and partially saccharified. Subsequent saccharification was performed simultaneously with fermentation. The initial total sugar content was adjusted to 15 % w/v and starch was enzymatically hydrolyzed using commercial α-amylase (Liquozyme) and glucoamylase (Novozyme) produced by NOVO. Fermentation was performed using Saccharomyces cerevisiae Hakken No. 1. Since the starch-rich flour contains useful nutrients and growth factors for microbes, the fermentation medium only required the addition of a nitrogen source (urea 1 g/L). The ethanol content after fermentation was approximately 8.7 % v/v with a fermentation ratio of 88.8 %. These results were obtained at a fermentation time of 60 h. One OPT yields 80 kg of starch-rich powder, equivalent to 33 liters of bioethanol.