Waste Glycerol Valorization and Recovery of 1,3-Propanediol: Focus on Process Optimization

This study investigates upscaling of bio-diesel industry crude glycerol to 1,3-propanediol at a 10 L scale, using C. butyricum L4. This strain showed higher potential for glycerol valorization having various toxins, affecting overall fermentation process. A COD mass balance of the 10 L fermentation with crude glycerol as a sole carbon source, showed a close balance of 90.02%, with 1,3-propanediol as the main metabolite (68.3% of total COD distribution). Three different aqueous two-phase extractions (SOE) were evaluated for 1,3-propanediol recovery. When (NH4)2SO4 and ethanol were used, the best outcomes were achieved (87.6% recovery, 19.6% by-products removal). The purification process is multi-step involving biomass removal, activated charcoal treatment, vacuum distillation, and isocratic chromatography. Vacuum distillation aids crude broth concentration with simultaneous removal of low distillates. Through isocratic chromatography in the final purification stage, approximately 82.22% yield and a purity exceeding 97% for 1,3-propanediol were achieved. The objective of this study is to advance environmental sustainability within the production process.