Ion exchange for product recovery in lactic acid fermentation

Lactic acid fermentation is a product-inhibited fermentation, and product recovery costs in downstream processing are considerable. In this paper the feasibility of ion exchange as a technique for product separation is investigated. In initial experiments an indigenously manufactured weak-base resin was found to show promise, and detailed equilibrium and kinetic data required for design and scaleup of the separation process have been obtained for this resin under conditions of relevance to the fermentation. The equilibria show Langmuir-type characteristics. The equilibria have also been established with HCl, which is a possible eluent. Kinetic studies show that the uptake can be described by a shrinking-core mechanism, with diffusion through the particle controlling. The effect of important medium components such as glucose and phosphate on the uptake of lactic acid has been established. Studies of the uptake of these components from fermentation media have been carried out.