2.6.1 Ultrafiltration and concentration of the fermentation
broth
Fermentation broth from the 1 m3 crude glycerol
fermentation in this study was used to evaluate the DSP. Removal of
biomass and protein was performed by ultrafiltration described by Zhanget al (Zhang et al., 2021 ). The
pH of the permeate from ultrafiltration was then adjusted to 9 by adding
50% NaOH water solution, and the glycerol content in the permeate was
adjusted to 4% by adding 80% raw glycerol. After the adjustment of pH
and glycerol content, the fermentation broth was fed to a rotary
evaporator (IKA, Germany) for concentration. In the first stage, 85% of
the water was evaporated under a heating temperature of
80oC and a vacuum pressure of 50 mbar. In the second
stage, the heating temperature was increased to 120oC
for the complete water removal.