Lactic acid recovery from fermentation broth using one-stage electrodialysis

One-stage electrodialysis (ED) for lactic acid recovery with two- and three-compartment water-splitting ED (WSED) was investigated using various ion-exchange membranes in order to overcome the inefficiency of two-stage ED, which consists of desalting ED for recovery and partial purification and subsequent WSED for acidification. The two-compartment WSED had a low current efficiency and high energy consumption in spite of a simple stack configuration. A three-compartment WSED successfully converted sodium lactate in the fermentation broth into lactic acid and sodium hydroxide with average yields of 96% and 93%, respectively. In relation to lactic acid purification, of the membranes tested in this study, the highest glucose rejection, 98.3%, was achieved using a PC 100D membrane. The CMS membrane rejected magnesium and calcium at levels as high as 81.7% and 78.5%, respectively. We concluded that the three-compartment WSED with properly chosen membranes, enabled lactic acid to be recovered directly from the fermentation broth. (C) 2001 Society of Chemical Industry.