Effective recovery of microalgal biomass using various types of emulsion polymers

Microalgae biomass has been considered as one of the potential feedstocks in biofuel production. Yet, biomass harvesting poses a challenge to the overall production cost due to its low cell density. Flocculation has been marked as one of the promising processes in microalgae harvesting technology. In this study, the first screening of two anionic (A-230, and A-330E) and five cationic polymers (C-810E, C-810EL, C-810EB, C-810ELH, and C-810EMB) followed by gravity settling with the mixed microalgae concentration of 2.24 g_TSS/L revealed that anionic polymers are less effective. Whereas all cationic polymers achieved above 90% harvesting efficiency. Therefore, the maximum mass recovery of 98.7% with 86.8 g_TSS/L sediment content was achieved by adjusting pH to 6-0.6 mL/L (115.178 mg/g_biomass) of C-810E followed by 15-min settling. The cationic polymer addition followed by settling would enable cost-effective downstream processing of microalgal biomass.