Keywords: lactic acid, fermentation broths, gelatin flocculation, particle size, HPLC, membrane pollution, electrodialysis, flocculants, flocculation rate, suspended solid removal, filtration flux, laser Doppler electrophoresis, high performance liquid chromatography
Flocculation of a lactic acid fermentation broth by gelatin
In the current study, flocculation of a lactic acid (LA) fermentation broth with three kinds of flocculants was performed in order to reduce membrane pollution during its subsequent electrodialysis. Gelatin was selected as the most suitable flocculant in comparison with others in terms of flocculation rate (FR), suspended solid (SS) removal rate, and filtration flux of the supernatant. Optimal flocculation conditions included the addition of 0.3 g/L gelatin, followed by 7 min stirring at 50°C. Under such conditions, the FR, SS removal rate, and filtration flux of the supernatant were 94.21%, 91.44%, and 800 mL/(min • m²), respectively. The average particle diameter of SS after flocculation (Dav) dropped by 66.48%, and the LA loss was 3.63%. The results indicate that gelatin flocculation can be applied to LA fermentation broths. The method proposed here can effectively remove SS and enhance the filtration flux, thereby decreasing membrane pollution and ensuring LA purity.