Lactic acid recovery from model solutions and fermentation broth by electrodialysis

Abstract

The effect of current density, initial concentration of diluting solution on lactic acid (LA) recovery by electrodialysis from both model solutions and real fermentation broth was investigated. In model solutions, LA recovery efficiency was 93-96% and it was independent of both, current density and initial concentration of diluting solution. The recovery rates at 33, 66 and 100 A·m-2 were 76, 175 and 272 g·m2·h-1 respectively and, clearly were linearly depended on current density. In the first stage of the process, both model solution and real fermentation broth showed similarities in the dynamic of LA recovery and water flux. With real fermentation broth, at current density of 100 A·m2 and 41.8g/l initial lactate concentration of diluting solution, the LA recovery rate and the water flux were 279.5 and 679 g·m-2·h-1, respectively. However, the recovery efficiency was decreased from a 93-96% range to 71%, compared to that in model solutions. The reason probably was that anion-exchange membrane was fouled by protein from broth.