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Commercial- and laboratory modified- cationic cassava starches and their composites with magnetic particles were examined for characteristics and separation efficiency. Scanning electron micrographs showed that cationic starch with an increasing degree of substitution (DS) value (0.0180 to 0.91) showed greater clumped polyhedral granules and became markedly enlarged with disintegrated boundaries. Zeta potential analysis revealed that the increase in the DS value in cationic starches resulted in an increase in positive charge. The maximum harvesting efficiency of 92.86 ± 0.46% was achieved when commercial cationic starch with DS 0.040 at 1.0 g L−1 was added to the Chlorella sp. solution. The maximum recovery capacity (10.20 ± 0.16 g DCW g starch−1) was recorded by using commercial cationic starch with DS 0.040 at a lower dosage of 0.1 g L−1. Their composites showed lower separation efficiency than the commercial cationic starches. The results suggest that the commercial cationic cassava starch with 0.040 DS shows great potential as a flocculant for algal separation. This first report of using commercial cationic cassava starch as a flocculant provides a low cost and convenient process to separate algal cells from the culture medium. Moreover, uncontaminated magnetic particle biomass allows for wide range of algal utilization in food and pharmaceutical biotechnologies.

C-phycocyanin was extracted from Nostoc commune TUBT05 and Oscillatoria okeni TISTR8549 using freezing and thawing and pulsed electric field treatments. The results confirmed that freezing and thawing can be used to extract c-phycocyanin from both cyanobacterial strains, whereas pulsed electric field treatment can be used only with N. commune, whose cell structure allows extraction by this technology. The number of freeze/thaw cycles, the extraction solution used and the number of electric pulses had statistically significant influences on c-phycocyanin concentration, purity, yield and the total protein content in the crude extracts (p ≤ 0.005). Exposure of N. commune to three cycles of freeze/thaw in sodium-phosphate buffer yielded the highest c-phycocyanin content, purity, and yield. The results suggest that careful selection of both the number of freeze/thaw cycles and the extraction solution is required to ensure high productivity. Transmission electron microscopy micrographs confirmed that the cell wall structure and organization of the thylakoid were different in the two species, requiring a significantly different number of freeze/thaw cycles and pulse applications for optimal c-phycocyanin extraction. Both cyanobacterial strains were shown to be potential alternative strains for c-phycocyanin production. However, further work is needed to improve c-phycocyanin concentration and purity. We suggest that this will require refinement of the cultivation conditions and improved purification processes.