The downstream processing of 1,3-propanediol fermentation broth using flocculation, reactive extraction, and reactive distillation was studied. Cellular debris and soluble protein in the broth were flocculated by combined use of chitosan and polyacrylamide at optimal concentrations of 150 ppm and 70ppm, respectively; the soluble protein in the broth decreased to 0.06g L-1, and the recovery ratio of the supernatant liquor to broth was greater than 99%. 1,3-Propanediol and other alcohols were extracted from the supernatant liquor by reacting with butyraldehyde. In a four-stage countercurrent extraction with the volume ratio of the extraction solvent to the aqueous phase being 20:100, more than 99% 1,3-propanediol acetal (2-propyl-1,3-dioxane) and 2,3-butanediol acetal (2-propyl-4,5-dimethyl-1,3-dioxolane) were recovered from the aqueous phase; 35% of the glycerol acetals were recovered. The acetals produced were hydrolyzed in a reactive distillation column using the strongly acidic cation-exchange resin as catalyst, the bottom product obtained was a mixture of 1,3-propanediol (407 g L-(1)), 2,3-butanediol (252 g L-1), glycerol (277 g L-1), and glycerol acetals (146 g L-1). (c) 2005 Society of Chemical Industry.