Drying of microalga Scenedesmus obliquus BR003 in a gas dryer at low temperatures

Abstract

Development of efficient and specific equipment to dry microalgae is essential for commercial use of these microorganisms that show high growth rates and biotechnological potential. Drying costs of microalgae biomass are still high and they should be reduced for the production of compounds with low added value. Therefore, we evaluated the drying process of the microalga Scenedesmus obliquus BR003 using low temperatures. S. obliquus BR003 is a robust microalga that shows high lipid productivity. At laboratory scale, it was observed that the biomass of S. obliquus BR003 was rapidly dried at low temperatures between 50 and 60 ° C. A gas dryer was used to evaluate the drying of the biomass of S. obliquus BR003 on a pilot-scale. The biomass was dried in less than 24 h using the gas dryer; however, the high moisture of the microalga biomass required a higher air renovation in the drying chamber. Computational fluid dynamics analysis of the gas dryer showed two important parameters to achieve greater effectiveness of heat and mass transfer rates during the drying process of the microalga biomass. It was concluded that a gas dryer suitable for the microalgae biomass should have multiple air injection points, and an efficient circulation and renovation system of air inside the drying chamber.