Analysis of the sodium lactate concentration process by electrodialysis

Electrodialysis is an interesting technique developed for recovering and purifying salts and acids from fermentation broths. In this work the concentration process of sodium lactate solutions was analyzed using a two-compartment electrodialytic unit equipped with commercial membranes (Neosepta AMX and CMX, Tokuyama Soda). The influence of several operating parameters on the overall process performance was investigated. For instance, it came out that at low current density values such membranes are able to operate a perfect separation of opposite charges, resulting in a good process performance. Moreover, water transport by electro-osmosis has to be considered, hence lowering the stack performance. Lastly, the reliability of a general mathematical model for this process was tested. The consistency between experiments and model results is fairly good, allowing the use of this model for design and optimization purposes.