Background: Potential of algal biomass for fuels, food, feed, and value-added
chemicals through autotrophic and heterotrophic metabolic pathways has long been
recognized. Existing downstream processing techniques, however, are not mature
enough to overcome either techno-economic barriers or sustainability concerns, among
which, energy-intensive microalgae harvesting is one of the biggest challenges.
Biological microalgae harvesting has been demonstrated as the most promising
technology in the near future that are economically viable and environmentally
friendly at the same time.
Methods: This paper critically reviews the current status and prospects of bioflocculation
for microalgae harvesting. Approaches for microalgae bio-flocculation are summarized, factors that influence
bio-flocculation of microalgae are indicated, and strategies for scaled-up applications are also discussed.
Results: Microalgae bio-flocculation approaches include auto-flocculating algae-based, bacteria-based, filamentous fungibased,
and plants extracts-based bio-flocculation. Type of flocculating microorganism, strain of target microalgae, and
various co-culturing conditions could all influence microalgal bio-flocculation efficiency. Utilization of the bioflocculated
algal biomass for fuel, food, feed, valued-added products, and for wastewater treatment are the two major
strategies for scaled-up application of microalgae bio-flocculation in the future.
Conclusion: Bio-flocculation of microalgae is a promising low-cost algae harvesting technology with unique advantages
over traditional harvesting methods. Future studies should not only focus on improving bio-flocculation efficiencies under
specific conditions, but should also investigate strategies for scaled-up applications. More attention should be paid on the
disposal and utilization of the harvested mixture of algal and flocculating microbial biomass.