Optimized 1,3-propanediol production from crude glycerol using mixed cultures in batch and continuous reactors

The production of 1,3-propanediol from crude glycerol and mixed anaerobic sludge was investigated in batch experiments and continuous reactors. Using a 2³ complete factorial design, the effects of the concentration of glycerol (22-30 g L^-1), KH₂PO₄ (1.50-2.00 g L^-1), and vitamin B12 (7-8 mg L^-1) were examined in batch reactors. As an evaluated response, the highest 1,3-PD yields occurred for high concentrations of vitamin B12 and low levels of KH₂PO₄, reaching 0.57 g g^-1 glycerol consumed. The variable glycerol concentration was not significant in the studied range. In addition, the condition that provided the best 1,3-PD yield was applied to an anaerobic fluidized bed reactor fed with crude glycerol (26.0 g L^-1), which was monitored as the hydraulic retention time (HRT) decreased from 36 to 12 h. The greatest 1,3-PD yield, of 0.31 g g^-1 glycerol, was obtained with an HRT of 28 h.