Integrated separation, dewatering and cell disruption of microalgae by means of a magnetic decanter
Microalgae offer numerous solutions to current challenges, among other things no agricultural soil is required for their cultivation, they do not compete with food and are technically advantageous for cultivation compared to macroalgae. However, due to the small size of microalgae, the challenge lies in the harvesting and dewatering steps, which are still very time- and energy-intensive and significantly lead to a negative cost balance. Due to their small size, specific weight and the formation of stable dispersions, the cells are difficult to separate for necessary dewatering, especially if oils are the valu-able product. Compared to state-of-the-art technology, which is too energy-intensive due to the high rotational speeds of the entire separator chamber, the concentration in the case of magnetic separa-tion is based on the force effect of inhomogeneous magnetic fields on magnetic particles. The use of magnetic particles (iron oxides - magnetite) simplifies both the separation and cell disruption by bind-ing onto the microalgae. However, the desired energy-efficient concentration of microalgae is not achievable with currently existing magnetic separator systems. Therefore, the aim of this research project is to develop a novel magnetic decantation system for the efficient separation, dewatering and disruption of photoautotrophic microalgae, which ensures the most positive CO2 balance possible for processes to obtain industrially relevant intracellular metabolites and bio-fuels.
In the course of the project the three working zones of the magnetic decanter: (i) particle separation zone; (ii) dewatering zone; (iii) cell disruption zone will be designed, manufactured and tested as prototypes on a laboratory scale. In a subsequent project phase, the integration of the working zones into one device is planned. The production of the prototypes is predominantly carried out with the exten-sive possibilities for additive manufacturing (3D printing). Finally, the development of the magnetic decanter will be accompanied by multiphysics simulations of the field distribution and hydrodynamics (FEM software COMSOL). Furthermore, the potential of the magnetic particles to facilitate the cell disruption of the harvested algae biomass as well as particle recycling will be investigated. In addition, obtained intermediates will be characterized.
Figure 1: Possible process scheme of algae harvesting, dewatering and cell disruption by means of a magnetic decanter