Continuous Production of 1,3-Propanediol Using Waste Glycerol with Clostridium beijerinckii NRRL B-593 Immobilized on Glass Beads and Glass Rushing Rings

C. Gonen, M. Gungormusler and N. Azbar

Abstract
Among the economically viable and ecologically acceptable solutions for the safe disposal of waste glycerol coming from biodiesel production, the biotechnological conversion of glycerol into a very high-value-added bioplastic raw material, namely 1,3 propanediol (1,3-PDO) seems to be very promising. This process is easy and environmentally friendly since it produces no toxic wastes. The results indicate that glycerol by-product is as amenable for 1,3-PDO production as pure glycerol. The immobilization process has important advantages such as smaller reactor volumes, shorter fermentation times, and higher yields. This work involves the study of 1,3-PDO production with industrial raw glycerol via immobilized culture of Clostridium beijerinckii B-593 on glass beads and glass rushing rings with industrial glycerol. Thereby, maximum volumetric productivity of 7 g L–1 h–1 corresponding to a product concentration of 13 g L–1 was achieved at 2 hours of hydraulic retention time (HRT) on glass beads. It was demonstrated that continuous production of 1,3-PDO from waste glycerol is feasible and the immobilized bioreactor systems outcompeted the conventional suspended culture bioreactors in terms of both productivity and operational stability.

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Keywords
1,3 propanediol, biopolymer, glycerol, biodiesel, immobilization, Clostridium beijerinckii