An effective process of harvesting Chlorella sp. biomass for bioresource by rapid flocculation in a helical tube
Zhe Lin, Chengxuan Li, Jiaheng Liu, Zhili Yang, Haiyang Zhang
Abstract
ABSTRACT An effective flocculation technique was developed for harvesting microalgal biomass, i.e., Chlorella 64.01, by using a home-made helical tube. The flow field characteristics in the tubes were studied by a computational fluid dynamic method. About 90% of cell recovery was achieved using 0.12 g/L diluted algal solution with an 18-s flocculation and 15 min sedimentation. The harvesting efficiency was significantly affected by the flow velocity. For a helical tube with 8 mm diameter, the optimal velocity was found to be 0.83 m/s to flocculate the microalgae. The helix diameter may have an impact on the flocculation due to the secondary flow intensity, and the 30-cm diameter was found to be a suitable choice. The residence time also plays a role in the recovery process as a competing effect between agglomeration and dissociation. Flocculation in a helical tube was proved to be a rapid and an effective approach for harvesting microalgae.