An efficient microalgal biomass harvesting method with a high concentration ratio using the polymer-surfactant aggregates process

The high cost and energy consumption related to the downstream harvesting and dewatering process is one of the most important bottlenecks limiting the commercial production of microalgal bioenergy. In this study, a novel microalgal biomass harvesting technique has been developed using polymer surfactant aggregates (PSAs). This approach has been applied to three different microalgal strains and two cynobacterial strains with a recovery efficiency of over 80%. In particular, the recovery efficiency of Chlorella sp. ZTY4 with a biomass concentration of 1.43 g·L-1 can be as high as 99.9% using 360 mg·L-1 poly (acrylic acid) (PAA) and 4 mM (1432 mg·L-1) cetylpyridinium chloride (CPC). In addition, with this PAA and CPC dosage, the recovery efficiency of Chlorella sp. ZTY4 remains above 90% for biomass concentrations up to 2.5 g·L-1. Furthermore, the water content in the harvested biomass is below 70% with a corresponding concentration ratio of 231. The total flocculation time needed for this technique is 20 minutes. The optimum dosage ratio for PAA to CPC ranges from 90 to 100 mg/mmol. Based on these results, an efficient harvesting method with a high concentration ratio is proposed to simplify the whole downstream harvesting and dewatering processes of microalgal biomass