On the Production of High-Purity Docosahexaenoic Acid from Heterotrophic Microalgae

Omega-3 fatty acids provide significant health benefits and are a popular nutritional supplement in the nutraceuticals industry. Omega-3 fatty acids such as docosahexaenoic Acid (DHA) and eicosapentaenoic Acid (EPA) have been reported to improve heart health and mental health. In addition, DHA consumption has been tied to improvements in infant cognitive development. Therefore, high-purity DHA is a desired ingredient in the production of infant formula. The omega-3 oils originating from fish tend to have carcinogenic risks in addition to a bad odor. In recent years, the industry trend has shifted to producing these omega-3 fatty acids via microalgae species– making it a profitable time to enter the DHA production market. The proposed design is for a plant to cultivate the Schizochytrium cells in the upstream process, and then extract and purify the desired omega-3 fatty acid oils in the downstream process. The project proposal called for production of 881,800 lb DHA per year, but our plant has the capacity to produce 1,148,000 lb DHA per year at a competitive price of $362.90 per lb of DHA. Clinton, Iowa was chosen as the plant location due to its proximity to the Mississippi River and the Archer Daniels Midland (ADM) plant, allowing for direct access to water and waste disposal. Our process is estimated to have an IRR of 153.8% with a NPV of $775,600,000 and a ROI of 206.5%. The process itself begins with fermentation of the microalgae cells, starting with lab-scale fermentors, increasing in size to seed fermentors, and finally scaling up to production fermentor size. Schizochytrium sp. is the strain of heterotrophic microalgae, chosen for its ability to accumulate lipids in high concentration, and its ability to produce DHA triglyceride in high selectivity with respect to other omega-3 fatty acids. Following fermentation, extraction operations are carried out with a hexane solvent and bead mill to extract the crude oils. The hexane is then evaporated and recycled back to the bead mill. The purification process of the crude oil involves saponification of the triglycerides into fatty acid salts. Acetic acid is then added to convert the salts into the final docosahexaenoic acid product. The saponification and protonation reactions take place in Scheibel columns. The final DHA product is 98% pure by mass, and will be sent to a pack out station to be packaged into pharmaceutical grade drums for customers