RECOVERY OF LACTIC ACID FROM FERMENTED BROTH USING AQUEOUS TWO-PHASE SYSTEM (ATPS) EXTRACTION: PROCESS SIMULATION AND VALIDATION

Abstract

Lactic acid (LA) is a commercially developed bulk chemical with greater interest due to its primary application as a monomer in synthesising polylactic acid (PLA), an eco-friendly biodegradable polymer. Though the microbial process for LA production is commercially developed, there are limitations concerning the downstream processes. Various conventional techniques like precipitation, membrane separation and liquid-liquid extraction (LLE) was developed to separate LA from the fermented broth, but these techniques have drawbacks in LA yields and recovery. Addressing these limitations, the study includes simulation of an aqueous two-phase system (ATPS) extraction, a combined approach of salting-out and LLE using an Aspen Plus® model. Further using the sensitivity analysis, the concentrations of salting-out agent (Ammonium sulphate) and extractant (Isopropanol) were determined. The model developed will be validated in the laboratory using synthetic solutions and fermented broth. The optimisation results demonstrated that three stages configuration of the extraction increased the LA yield from 80% to 96%. Isopropanol is reduced from 45% to 29% and ammonium sulphate from 57% to 29%. Further work is recommended on developing the binary interactions for this SOE system. Moreover, a study on the economic feasibility and upscaling is required.