Scaling-up and techno-economics of ethanol production from cassava starch via separate hydrolysis and fermentation

Abstract

Nowadays bioethanol is being used extensively in fuel production because of its technical feasibility, economically competitive, and environmentally friendly. It is expected that biofuel will contribute to 30% of the global energy demand by 2050. Therefore, it is very important to investigate any cost-effective bioprocessing that can improve the overall production yield. The study aims to produce bioethanol from cassava starch by Kluyveromyces marxianus at a laboratory scale and a 5L fermentation rig. A separate hydrolysis and fermentation (SHF) process of cassava starch was introduced due to high sugar content in starch, using a thermoanaerobe able to reduce the cooling time after hydrolysis. A combination of 0.35% v/w amylase and 0.20% v/w amyloglucosidase used in the hydrolysis of cassava starch produced 19.18 g/L of sugar. A 15 g/L of K. marxianus showed to be the best yeast concentration which could produce the highest bioethanol, 42.85 g/L. When the laboratory scale was scaled up to 5 L fermentation, the result was comparable at 42.33 g/L. The same SHF parameters in laboratory scale had been proven to be effective in a larger scale fermentation based on similar results obtained. Simulation using SuperPro software indicated that 50.13% of starch can be converted into ethanol.