Harvesting of freshwater microalgae, Arthrospira sp. using flocculation method

Arthrospira platensis is a well-known microalgae species that is widely used as the protein and vitamin supplements to aquatic organisms, as well as a complementary dietary ingredient for human. Efficient biomass recovery or harvesting of different algal species is nevertheless a vital bottleneck for a large-scale biorefinery process. Due to its high-efficiency, cost-effectiveness and scalability, chemical flocculation was performed to harvest the biomass production of Arthrospira platensis. In the present study, the flocculation was conducted using three chemical flocculants: chitosan, aluminium sulphate, and copper (I) chloride in hydrochloric acid. The harvesting was performed and optimised using one factor at a time (OFAT) and it was found that chitosan was the most effective flocculant, with 99.96% flocculation efficiency using 90 mg/L dosages while the settling time was above 80% efficiency at the first 5th minute and remained constant until the 60th minute of the experiment. Furthermore, chitosan was studied as a biodegradable polymer and non-toxic coagulant, which may be less harmful than other chemicals.