Abstract
The present study describes the production of the value-added chemical 1,3-propanediol (1,3-PD) from crude glycerol, a waste by-product formed during biodiesel production. The efficiency, robustness, and stability of the process were improved by immobilization of the anaerobic bacterium Clostridium butyricum into a polyvinyl alcohol (PVA) hydrogel. The highest average productivity, 6.8 ± 0.2 g/(L·h), was achieved in 10 consecutive, repeated batch fermentations, with an initial concentration of pure glycerol 45.5 ± 0.7 g/L, after 2.5 hours. The highest final concentration and yield of 1,3-PD, 28.3 ± 0.6 g/L, and 0.42 ± 0.01 g/g, respectively, were achieved in eleven repeated batch fermentations, after increasing the initial pure glycerol concentration to 70.4 ± 1.9 g/L. Two different types of crude glycerol, produced from used cooking oil (UCO) and rapeseed oil (RO), were tested in repeated batch fermentations, with an average productivity achieved of 2.3 ± 0.1 and 3.5 ± 0.3 g/(L·h), respectively. The highest final concentration and yield of 1,3-PD, 12.6 ± 0.9 g/L, and 0.35 ± 0.02 g/g, respectively, were observed in fifteen repeated batch fermentations with RO crude glycerol. An excellent stability of the immobilized anaerobic bacteria and increase of productivity in fermentation of crude glycerol was demonstrated.
Highlights
The present study describes the production of the value-added chemical 1,3-propanediol (1,3-PD) from crude glycerol, a waste by-product formed during biodiesel production
The objective of this study was to demonstrate a positive effect of cell immobilization on the fermentation of pure glycerol, and crude glycerol, produced from different sources, such as rapeseed oil (RO) and used cooking oil (UCO)
The observed volumetric productivity, 1.5 g/(L·h), and product yield, 0.40 g/g (0.49 mol/mol), were close to those reported for a batch fermentation carried out with free cells of a similar microbial strain of C. butyricum (1.9 g/(L·h), 0.62 mol/mol) [33]
Summary
The present study describes the production of the value-added chemical 1,3-propanediol (1,3-PD) from crude glycerol, a waste by-product formed during biodiesel production. The highest final concentration and yield of 1,3-PD, 28.3 ± 0.6 g/L, and 0.42 ± 0.01 g/g, respectively, were achieved in eleven repeated batch fermentations, after increasing the initial pure glycerol concentration to 70.4 ± 1.9 g/L. 1,3-propanediol (1,3-PD) is a valuable, bi-functional chemical compound that is widely used in the food, cosmetic, and pharmaceutical industries. It may be used as an intermediate in the organic synthesis of biocides and heterocyclic compounds, or transformed by chemical catalysts to create new types of polymers, with enhanced features, especially polyethers, polyurethanes, and polyesters [1,2,3,4]. Krische and co-workers have recently developed synthetic routes transforming 1,3-PD into molecules of pharmaceutical importance, such
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