Ethanol production from waste glycerol using glucose as co-carbon source

Abstract

Ethanol was produced by sole glycerol and glycerol-glucose fermentation using Enterobacter aerogenes TISTR 1468. The initial experiment was set up with waste glycerol as a sole carbon source with initial concentration ranged from 0, 8.7, 23.4, 43.4, to 63.1 g L−1 in 100-mL serum bottles under controlled condition at 30°C for 240-hr fermentation. Liquid samples, during the fermentation, were collected to quantitate concentrations of volatile fatty acids and glycerol, whilst gaseous samples were collected to quantitate CO2 and CH4 constituent. E. aerogenes TISTR 1468 produced maximum ethanol concentration and yield of 215.1 mM and 0.71 mol mol−1 after 72-hr fermentation with the initial waste glycerol concentration of 63.1 g L−1 (equivalent to 79.11 g COD L−1). The ethanol production from glycerol-glucose fermentation was set up based on the initial COD concentration equivalent to 79.11 g COD L−1 with varying glycerol-glucose ratios of 1:1, 10:1, and 100:1. At the ratio of 100:1, maximum ethanol concentration and yield were 232.8 mM and 0.59 mol mol−1 after 24-hr fermentation. Addition of glucose as co-carbon did improve ethanol concentration.