Pretreatment of Starch-Free Sugar Palm Trunk (Arenga pinnata) to Enhance Saccharification in Bioethanol Production

¹ Renewable Energy Research Centre, Department of Chemical Engineering, Faculty of Engineering, Universitas Muhammadiyah Surakarta, Jl. A. Yani Tromol Pos 1, Pabelan, Kartasura 57102, Surakarta, Indonesia
² Department of Chemical Engineering, Faculty of Engineering, Diponegoro University, Jl. Prof. Soedarto, SH-Tembalang Semarang 50275, Indonesia
³ Master Program of Environmental Science, School of Postgraduate Studies, Diponegoro University, Jl. Imam Bardjo, SH-Semarang 50241

^* Corresponding author: kusmiyati@ums.ac.id and psea_ums2014@yahoo.com

Abstract

Starch-Free Sugar Palm Trunk (Arenga pinnata) can be utilized to produce bioethanol because of their high lignocellulosic contents. Production of bioethanol from lignocellulosic materials consist of pre-treatment, saccharification and fermentation processes. In this work, conversion of starch-free sugar palm trunk (Arenga pinnata) to fermentable sugar and bioethanol was carried out through g pretreatment, saccharification and fermentation processes. The pretreatment was carried out by addition of 1% (v/v) HNO3 and NH4OH for 30 min and 60 min, respectively. The saccharification was carried out at enzyme celullase loadings of 10 and 20 FPU/g and substrate loadings of 10 and 20 g for NH₄OH pretreated samples. Fermentation was carried out using two methods i.e. separated hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) techniques. The results showed that pretreatment using NH₄OH was more effective than HNO₃ for 60 minutes. IFurthermore, the results also presented the reduction of the lignin content of 9.44% and the increase of cellulose content to 18.56% for 1% (v/v) NH₄OH 60 min of pretreatment. The increase of enzyme cellulase (20 FPU/g substrate) and substrate loading (20 g) could produce more reducing sugar (17.423 g/L and 19.233 g/L) than that at 10 FPU/g substrate and 10 g substrate (11.423 g/L and 17.423 g/L), respectively. The comparison of SHF and SSF showed that SHF process yielded higher ethanol (8.11 g/L) as compared to SSF (3.95 g/L) and nontreatment process (0.507 g/L) for 72 h..