Continuous production of 1,3-propanediol using raw glycerol with immobilized Clostridium beijerinckii NRRL B-593 in comparison to suspended culture

The continuous production of 1,3-propanediol (1,3-PDO) was investigated with Clostridium beijerinckii NRRL B-593 using raw glycerol without purification obtained from a biodiesel production process. Ceramic rings and pumice stones were used for cell immobilization in a packed-bed bioreactor. For comparison purpose, a control bioreactor with suspended culture was also run. The effect of hydraulic retention time (HRT) on the production of 1,3-PDO in both immobilized and suspended bioreactors were also investigated. The study revealed that HRT is an important factor for both immobilized and suspended systems and a HRT of 2 h is the best one in terms of volumetric production rate (g 1,3-PDO/L/h). Furthermore, cell immobilization had also obvious benefits especially for the robustness and the reliability of the production. The results indicated that cell immobilization achieved a 2.5-fold higher productivity in comparison to suspended cell system. Based on our results, continuous production of 1,3-PDO with immobilized cells is an efficient method, and raw glycerol can be utilized without any pretreatment.