Effect of biodiesel glycerol type and fermentor configuration on mixed-acid fermentations.

The MixAlco process biologically converts biomass to carboxylate salts that may be converted to a variety of chemicals and fuels. This study examines the viability of different types of glycerol as a potential feedstock. Batch fermentations of crude biodiesel glycerol were compared to distilled and refined glycerol. Continuous fermentations were performed in a CSTR and a packed-bed fermentor with refined glycerol. While crude and distilled glycerol are difficult to process industrially, all types of glycerol performed well during MixAlco fermentations, producing acid concentrations above 22 g/L and conversions of greater than 65%. The CSTR configuration produced excellent acid concentrations (16 g/L) while the packed-bed configuration produced high amounts of cell material for use in cell extract products or starter cultures.