Process design and economic studies of two-step fermentation for production of ascorbic acid

The current study presents the conceptual design of a chemical plant for an annual production of 500 tonne ascorbic acid or Vitamin C with a high purity of 95% via fermentation of d-sorbitol. In this study, two-step fermentation with a single culture process is operated with a proper ISO 14000 Environmental Management procedure. A process flow diagram of the processing plant and the plant-wide simulation flowsheet that was generated by SuperPro Designer Simulation software, as well as the material and energy balances are also depicted. Meanwhile, the process is optimized through the recycling of sorbose and heat integration. By recycling sorbose, the production of ascorbic acid has increased by 24% while the total energy consumption had reduced by 20% after heat integration. Furthermore, economic and sensitivity analysis was performed to calculate the profitability of the plant and predict the effect of market conditions on the investments. After the economic analysis, total capital investment and total production cost for the best scenario were found to be roughly USD 52 million and USD 43 million, respectively with a return on investment of 78.73% and a payback period of 1.17 years since the selling price of Vitamin C is high.