A Magnetic Approach to Sustainable Chlorella vulgaris Harvesting: Methods and Applications

Microalgae are unicellular microorganisms with many applications; however, their high harvesting costs compromise their large-scale use. Magnetic separation has been explored as a potential solution for overcoming harvesting challenges. In addition to promoting microalgal harvesting, the magnetic capacity of particles allows their recovery, regeneration, and reuse, lowering process costs and promoting a circular economy. This study explored the impact that production conditions have on the properties of magnetic particles and, consequently, on the harvesting of Chlorella vulgaris. By using the base NH4OH to produce magnetite, it was possible to reduce the particle size and increase their magnetic capacity, essential parameters for a successful harvesting. In addition, by increasing the stirring time and the temperature (80 °C), the particle size was further reduced. As a result, microalgal harvesting was increased by optimising magnetite production.