Novel Dual Reactive Distillation Process for Eco-efficient Lactic Acid Recovery and Purification from Fermentation Broth

Process intensification (PI) is a major area of interest for downstream processing in biorefineries, where dilute aqueous streams must be processed to separate and purify valuable components. For example, lactic acid (LA) purification faces these challenges as the feed consists of a dilute aqueous mixture of LA and other organic acids as impurities. These characteristics result in high energy requirements, large equipment, and multiple operations when considering conventional technologies. The combination of otherwise individual processing tasks is enabled by exploiting synergies following PI principles, which improves energy efficiency and reduces the processing equipment's size. This study presents a new conceptual design of an intensified dual reactive dividing wall column (R-DWC), applied to lactic acid purification. This CAPE study is the first to investigate the effect of impurities that disrupt the reaction and the separation. The approach taken in this study is a mixed methodology based on a decomposition approach, shortcut calculations, and rigorous process simulation in Aspen Plus. The intensification and the heat integration of this new realistic process led to a more eco-efficient operation in terms of material intensity (over 50 % reduction), water consumption (35 % reduction) and energy intensity (25 % reduction) compared to a 4-column flowsheet that does not account for reactive impurities and additional azeotropes. The recovery (> 95 %) and purity (88 % w/w LA) targets were successfully achieved, and the acid impurity was effectively removed.