Coagulation-membrane filtration of Chlorella vulgaris

Filtration-based separation of Chlorella vulgaris, a species with excellent potential for CO2 capture and lipid production, was investigated using a surface-modified hydrophilic polytetrafluoroethylene (PTFE) membrane. Coagulation using polyaluminum chloride (PACl) attained maximum turbidity removal at 200 mg L−1 as Al2O3. The membrane filtration flux at 1 bar increased as the PACl dose increased, regardless of overdosing in the coagulation stage. The filtered cake at the end of filtration tests peaked in solid content at 10 mg L−1 as Al2O3, reaching 34% w/w, roughly two times that of the original suspension. Differential scanning calorimetry (DSC) tests demonstrate that the cake with minimum water–solid binding strength produced the driest filter cake. Coagulation using 10 mg L−1 PACl as Al2O3, followed by PTFE membrane filtration at 1 bar, is an effective process for harvesting C. vulgaris from algal froth.