The ethanolic fermentation of glucose by yeast-in
combination with liquid-liquid extraction of the product.
ethanol using n-dodecanol as the solvent has been
investigated in a continuous laboratory pilot plant.
Severe emulsification problems occurred in initial
experiments and the emulsification was found to be
caused by free yeast cells in the aqueous/solvent mixtures.
The emulsification problems were overcome by immobilisation
of the yeast in calcium alginate beads.
A number of continuous runs were made using fresh
feed glucose concentrations between 10% wt and 45.8% wt.
The duration of run was sufficient for the system to
attain equilibrium and the run lengths at each glucose
concentration were between 7 - 17 days. At all glucose concentrations the steady state ethanol concentration
in the fermenter was between 2.8% wt and 3.8% wt ethanol
with glucose to ethanol conversions between 70.9% and
95.7% and the corresponding overall yield of ethanol on
glucose between 67.0% and 91.9%.
The glycerol concentration in the fermenter increased
from 0.27% to l.08% wt at the maximum glucose feed
concentration. The dilution rates based on the fresh feed were between 0.06 - 0.27 h-1 The fermenter productivities varied between 10.2 -
14. b g ethanol l-lh -1.
The use of 45.8% wt glucose feed would enable a
77.8% reduction in the volume of aqueous effluent from
A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.