Process and cost modeling of lactic acid recovery from fermentation broths by membrane-based process

Process and cost models for lactic acid recovery from fermentation broths at an annual capacity of 100,000 kg were developed as a research tool to evaluate an alternate process technology. The models were developed using SuperPro (R) Designer software by gathering the optimized data from the laboratory scale experiments. Sizing of unit operations, chemicals and utility consumptions, and estimation of capital and operating costs with the cost breakdown analysis were acquired from the simulation. A membrane-based process design was proposed in this study. The processes mainly consisted of microfiltration for cell removal, a series of ultrafiltration for eliminating proteins, and the integrated reverse osmosis systems to recover, pre-concentrate, and pre-purify lactic acid. Among the 3 proposed process designs, the in-parallel membrane-based process exhibited the highest lactic acid recovery yield, while the purity remained sufficiently high compared to commercial-grade products. The number of unit operations was found to be responsible for high production cost, in terms of both investment and operating costs. Omitting centrifugation and ultrafiltration at a 30-kDa molecular weight cut-off and use of the in parallel integrated brackish water reverse-osmosis membrane units could lower operating costs by 23-31% for various fermentation broths that entered the downstream processing units.