Optimizing the operational conditions for microalgae biomass drying using tray dryers

Drying is a critical yet energy-intensive step in the valorization of microalgae biomass, essential for ensuring long-term stability and enabling downstream processing. This study investigates the technical feasibility and performance of tray drying as an alternative to conventional methods, using Chlorella sp. biomass. Experiments were conducted at drying temperatures ranging from 60 to 80 °C and biomass layer thicknesses between 0.3 and 1.0 cm, simulating industrial tray dryer conditions. Drying kinetics were assessed through moisture ratio and water content conditions, with a power-law model applied to describe the drying rate as a function of moisture content. The results demonstrated that thinner layers and higher temperatures significantly reduced drying time, with full dehydration within 5 h at 80 °C and 0.3 cm thickness. However, spectrophotometric analysis revealed a trade-off between drying efficiency and biomass quality, with pigment degradation increasing with temperature and time. A polynomial model was developed to predict pigment deterioration based on operational parameters. These findings provide a robust foundation for the design and scale-up of tray drying systems and offer a practical framework for optimizing the balance between process efficiency and product quality in microalgae biorefineries.