Harvesting of Microalgae Biomass via Coagulation and Flocculation Process

As microalgae has become an important source of biodiesel, large scale harvesting of microalgae biomass using commercial chemical flocculants like alum is not cost-effective and the resulting sludge is toxic for downstream usage. In this project, several natural flocculants were synthesized in liquid form to harvest Chlorella vulgaris. Flocculation jar tests (30 minutes stirring, followed by sedimentation) were carried out to test the effectiveness of natural flocculants to recover microalgae biomass as well as to study the effects of pH, flocculant dosage and stirring speed on the flocculation efficiency of microalgae. Chitosan and maize seeds were proven to be effective flocculants as they achieved above 80% efficiency after 1 hour and 4 hours sedimentation respectively.