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Macrofiltration-A leap towards high efficiency microalgal harvesting: A case study using Scenedesmus acuminatus
- Xiao, Jingrong, Liu, Rui, Yang, Li, Hu, Qiang, Zhang, Xuezhi
- Algal research 2019 v.37 pp. 1-10
- Scenedesmus, biomass, case studies, cellulose, commercialization, fouling, harvesting, microalgae, porosity, scanning electron microscopy, ultrafiltration
- In order to develop efficient membrane based harvesting techniques to accelerate microalgal commercialization, macrofiltration membranes of mixed cellulose with pore sizes of 0.45, 1.2, 3, 5, and 8 μm were evaluated for Scenedesmus acuminatus harvesting. The influences of pore size on the changes in membrane flux and flux recovery were investigated, followed by a SEM analysis of the fouled membranes. The performance of S. acuminatus harvesting using the 5 μm membrane was then compared with an ultrafiltration membrane, with both operating under a cross-flow mode. Macrofiltration operated with dead-end mode was further developed to achieve higher flux and higher solid content in the harvested biomass. The results showed that the 5 μm mixed cellulose membrane achieved the highest average flux due to its excellent anti-fouling performance. SEM images revealed that the presence of non-cellular and cellular foulants were responsible for the fouling of the smaller sized membranes, and membranes larger than 5 μm, respectively. Macrofiltration membrane harvesting was more efficient when a dead-end rather than a cross-flow operation was used. The average flux from a multiple-times filtration cycle reached 1845 ± 105 L·m−2·h−1 for the dead-end operated 5 μm macrofiltration membrane, which was 16-fold higher than that obtained using a cross-flow ultrafiltration membrane (107 ± 14 L·m−2·h−1). The solid content of macrofiltration-harvested biomass was 24%. This high flux and high solid content achieved through macrofiltration represents a great leap towards high-efficiency microalgal harvesting.