2.2. Raw materials
The biodiesel producer P.N. Pettas S.A. (Patras, Greece) kindly
supplied the crude glycerol and SFM used in this study. The
main components of SFM are protein (26.62%), fiber (19.54%), ash
(6.83%) and oil (0.93%) (Kachrimanidou et al., 2013). The crude
glycerol stream contained 91% (w/w) glycerol, 1.33% (w/w) Na+
and approximately 0.424% (w/w) non-polar compounds. The initial
crude glycerol stream was pretreated via overnight decanting
using separation funnels in order to reduce the content of non-polar
compounds (0.099%, w/w) that inhibited PHB formation. The pretreated
crude glycerol contained a slightly higher glycerol content
(92.4%, w/w). Detailed description of crude glycerol pretreatment
has been reported by Kachrimanidou et al. (2014).