Separation of Microalgae by a Dynamic Bed of Magnetite-Containing Gel in the Application of a Magnetic Field

Abstract

Microalgae are now known as potential microorganisms in the production of chemicals, fuel, and food. Since microalgae live in the sea and the river, they need to be harvested and separated and cultured for further usage. In this study, to separate microalgae, a bed of magnetite-containing gel (Mag gel, 190 µm) was packed in the column by the application of a magnetic field for the separative elution of injected microalgae (including mainly four species), cultured at Saga University in Japan. The applied magnetic field was set at a constant and dynamic-convex manner. At a constant magnetic field of 0.4–1.1 T, the elution percentage of the microalgae at less than 5 µm was 30–50%. At 1.1 T, the larger-sized microalgae were eluted at a percentage of 20%, resulting in the structural change of the bed by the applied magnetic field. In a convex-like change of the magnetic field at 1.1 T ⇄ 0.4 T, the smaller-sized microalgae were selectively eluted, whereas at 1.1 T ⇄ 0.8 T, the larger-sized microalgae were eluted. Dynamic convex-like changes by the magnetic field selectively eluted the microalgae, leading to the separation and the extraction of potential microalgae.