Potential of Fermentable Sugar Production from Napier cv. Pakchong 1 Grass Residue as a Substrate to Produce Bioethanol

Bioethanol is one of the most significant renewable fuels. The major sources of bioethanol production are food crops such as corn, sugarcane, rice, wheat and sugar beet. However, utilization of food crops to produce bioethanol could affect the food sources and disrupt the food to population ratio. To overcome these issues, the utilization of lignocellulosic materials such as wheat straw, grass and crop residues to produce bioethanol has been developed for second-generation fuel, since those resources are abundant, cheap and renewable. Napier Pakchong 1 grass (NPG) residue is a lignocellulosic waste obtained from the process of biogas production that can be used as an alternative material for bioethanol production. This research aims to study on the potential of fermentable sugar production from NPG residue. The materials were pretreated with different concentrations of sodium hydroxide (NaOH), followed by enzymatic hydrolysis for saccharification. The results suggested that pretreatment with 3.0% (w/v) NaOH solution at 121̊C for 60 minutes provided the highest lignin removal of 86.1% (w/w) and enriched cellulose fraction from 36.4 to 75.6% (w/w). The enzymatic hydrolysis was conducted by varying enzyme loading volume and total solid contents (TS) at pH 4.8, 50̊C for 72 h. The hydrolysis with enzyme loading volume of 2.0 ml/g of substrate and 10% (w/v) of TS were optimal for saccharification giving the reducing sugar yield of 768 mg/g of pretreated biomass or equal to 64 g/L and glucose yield of 522 mg/g of pretreated biomass or equal to 43 g/L. The reducing sugar will be used as a starting material for yeast to produce bioethanol.