Extraction of 1,3-propanediol from glycerol-based fermentation broths with methanol/phosphate aqueous two-phase system

An aqueous two-phase system consisting of methanol and phosphate was used to extract 1,3-propanediol from glycerol-based fermentation broth. Methanol not only extracted 1,3-propanediol effectively from the broth through forming aqueous two-phase system with phosphate, but also allowed the recovery of phosphate by dilution crystallization through adjusting the pH. At 35% (v/v) methanol, saturated concentration of phosphate and a pH of 10.7, the partition coefficient and recovery of 1,3-propanediol reached 38.3 and 98.1%, respectively. The recovery of phosphate in the bottom phase reached 94.7% when 1.5 volume of methanol was added to the salt-rich phase after adjusting the pH to 4.5. At the same time, the main byproduct, 2,3-butandiol was also extracted with high efficiency. In addition, cells and proteins could be simultaneously removed from the fermentation broth, and the removal ratios for cells and proteins reached 99.85% and 92.4%, respectively.