Economic evaluation of an integrated process for lactic acid production from ultrafiltered whey

Abstract

Lactic acid can be manufactured either by chemical synthesis or by fermentative processes. In recent years, the amount of lactic acid obtained by biotechnological methods has increased. The highest cost in the traditional process of lactic acid production by carbohydrate fermentation lies in the separation steps that are needed to recover and purify the product from the fermentation broth. An integrated process for food grade lactic acid production from whey ultrafiltrate is evaluated in this work. This process consists in the following steps: fermentation, ultrafiltration, ion exchange, reverse osmosis and final concentration by vacuum evaporation. The proposed process was demonstrated to be economically viable. The annual cost resulted to be 1.25 US$/kg for 50% (w/w) lactic acid. The highest contribution to the total investment cost corresponds to the concentration step, representing 40% of the total cost, whereas the fermentation step requires the highest operating cost (47% of the total operating cost).