Alkaline Delignification of Oil Palm Empty Fruit Bunch Using Black Liquor from Pretreatment

Abstract

Bioethanol is providing one window of potential alternative energy. Lignocellulosic from oil palm empty fruit bunch (EFB) could be a promising bioethanol raw material because of abundant resources and it will not interfere food supply. Pretreatment is a one of the steps in the bioconversion of lignocellulosic material. Pretreatment also contributes the largest cost in the bioethanol production and produces black liquor as a wastewater that provides environmental impacts. Black liquor recycling is expected to increase economic efficiency by reducing the cost of pretreatment and the amount of wastewater. This experiment used black liquor and its mixture with NaOH solution as pretreatment solution. The pretreatment process was conducted in a 5-liter reactor at 150oC. The result using only black liquor gave the lowest value compared to other solutions. The addition of NaOH solution into black liquor caused increasing the cellulose content and delignification EFB by 57.18% and 51.62%, respectively. The maximum glucose concentration in the variation of pretreatment solutions: NaOH 2.5 M, black liquor, and black liquor with NaOH solution addition were 93.80 g l-1, 52.55 g l-1 and 87.05 g l-1, respectively, at a pretreated biomass loading of approximately 15% (w/v) with an enzyme dosage of 30 FPU g/dry biomass.