Methods coagulation/flocculation and flocculation with ballast agent for effective harvesting of microalgae

Area of Science:

• Biotechnology
• Environmental Science
• Microalgal Cultivation

Background:

• Efficient harvesting of microalgae like Chlorella vulgaris is crucial for biofuel and bioproduct applications.
• Conventional harvesting methods can be energy-intensive and costly.
• Flocculation offers a promising alternative for microalgal biomass recovery.

Purpose of the Study:

• To investigate the flocculation efficiency of harvesting Chlorella vulgaris GKV1.
• To evaluate the impact of coagulants, flocculants (PAA, PEO), ballast agents, dosage, and sedimentation time.
• To determine the most suitable flocculation method for microalgal harvesting.

Main Methods:

• Laboratory cultivation of Chlorella vulgaris GKV1.
• Testing various coagulants (FeCl3·6H2O) and flocculants (polyacrylamide, polyethylenoxide).
• Assessing the use of flocculated biomass as a ballast agent.
• Optimizing coagulant/flocculant dosage and sedimentation time.

Main Results:

• A mixture of FeCl3 (50 mg/l) and PEO-based Sibfloc-718 (7.5 mg/l) achieved ~90% flocculation efficiency in 5 minutes.
• Using Sibfloc-718 (7.5 mg/l) with 10% flocculated biomass also yielded ~90% efficiency within 5 minutes.
• Polyacrylamide (PAA) and Polyethylenoxide (PEO) showed good efficiency at 0.025 g/l and 0.015 g/l, respectively, without pH adjustment.

Conclusions:

• Flocculation is a highly effective method for harvesting Chlorella vulgaris GKV1.
• Coagulant-flocculant mixtures and flocculant with ballast agents are efficient harvesting strategies.
• The study identified optimal conditions for rapid and high-efficiency microalgal biomass recovery.