STUDY OF BIOETHANOL PRODUCTION USING RAW CASSAVA WASTE PULP (ONGGOK) SUBSTRATE BY AMYLOLYTIC FUNGI AND Saccharomyces cerevisiae

• Main Author: Danti Agustiani, Eka
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/34715
• Institution: Institut Teknologi Bandung

Ethanol is one of the alternative renewable energy sources with low emision grade. Bioethanol is ethanol made from organic matter , such as sugar or any biomass that can be converted into sugar. Cassava waste pulp (onggok) has the potential to be utilized for bioethanol production due to its high content of starch (60%-70%). Since efforts to reduce cost of ethanol production are very important, this research used raw cassava waste pulp as the substrate. The solid state fermentation (koji form) followed with submerged fermentation was carried out using amylolytic fungi and Saccharomyces cerevisiae. At the first stage, seven amylolytic fungi; Aspergillus niger, Aspergillus awamori, Aspergillus oryzae, Rhizopus oligosporus, Rhizopus arrhizus, Rhizopus stolonifer and Rhizopus oryzae, in rice bran koji form, were screened for their bioethanol producing capabilities with raw onggok as the substrate. The fermentation conducted in Erlenmeyer flasks with funnels which were connected into water. The best result showed 8.2% v/v bioethanol produced by R. oligosporus. The chosen isolate was adapted to grow in rice bran agar medium. A new koji culture then made with adapted R. oligosporus in supplemented rice bran (added with K2HPO4 and (NH4)2SO4) and shaked at 140 rpm for 48 h. The suplemented koji used in submerged raw onggok fermentation in Erlenmeyer flask closed with rubber cap for seven days. Bioethanol produced by the method was 4,6 g from 30 g raw onggok. Another experiment used mix culture fermentation with Saccharomyces cerevisiae in submerged fermentation, while single culture of R. oligosporus was used as the control. Submerged fermentation was conducted in Erlenmeyer flask closed with swan neck tube as the cap for four days. From 30 g raw onggok, the mix culture fermentation produced 6,7 g, while single culture produced 6,6 g ethanol. Based on this result, single culture fermentation of R. oligosporus was carried out, using three parts of onggok substrate and one part of rice bran koji without any supplement. Ethanol formation was observed after 7, 14, 21 and 28 days of fermentation. The highest level of reducing sugar was observed on day 21 after fermentation. The highest ethanol yield was 18,7 g from 30 g raw onggok, that was reached after 28 days with theoretical conversion of efficiency 149.2%. At that point, the solid biomass has decreased 50,5% from the initial biomass before fermentation. After 28 days fermentation viable mycelium and chlamydospores of R. oligosporus was observed.