3.2.1.1. Glycerol purification. A typical composition for a crude glycerol
stream obtained from the biodiesel production process is as
follows (% w/w): 32.59% methanol, 60.05% glycerol, 2.62% NaOCH3,
1.94% fats, and 2.8% ash. Although there are studies that use consortia
of microorganisms for the production of PHB from crude
glycerol (Dobroth et al., 2012), in this work glycerol is purified before
the fermentation step by physical methods up to 98% weight
according to the methodology described by Posada et al. (2009)
(Fig. 3).