Kinetic study and modelling of drying of Chlorella vulgaris

Abstract

Microalgae are an incredibly diverse group of eukaryotic organisms that thrive in a wide range of habitats. Microalgae not only have a significant potential as a supplement of fossil fuels but also as a source of a wide spectrum of chemicals, including PUFAs (Polyunsaturated fatty acids), carotenoids, and antioxidants. They are the most efficient biomass producer compared to others. But there is a great challenge to use this microorganism efficiently. Microalgae grow in aqueous media (Growth media, Waste water etc.). To use it in bio-fuel production, producing different chemical extraction or making nutraceutical product for human or animal consumption, it has to be dried first. Extensive studies have been done on the benefits and uses of microalgae, but very few are focusing drying. In this study, one species of microalgae (Chlorella vulgaris) was studied for determining the drying kinetics in the moisture removal process. Drying behavior data was obtained from TGA (Thermogravimetric analysis) and DSC (Differential scanning calorimetry). The moisture content of biomass decreased rapidly with increase in temperature and an approximate peak was obtained in the temperature range of 65-80⁰C. Four non-isothermal drying models were obtained from four popular drying kinetics model generally used for studying drying kinetics of agricultural products. These models were evaluated based on the coefficient of determination (R2) and reduced chi-square (χ2). Page’s model was found to be the best fitted model for describing the drying kinetics.