Bioflocculation as an innovative harvesting strategy for microalgae

Microalgae are a promising new source of biomass for the production of third generation biofuels but, so far, the majority of microalgal biomass has been used for high-value applications. New low-cost technologies are needed to make the production and processing of microalgae economically feasible for low-value applications. A major challenge lies in the harvesting of microalgae, which requires a cost-efficient separation technology. Flocculation, especially bioflocculation, is an attractive low-cost separation technology. Various new bioflocculation strategies have been claimed to generate major advances in cost-efficient harvesting. Here, we review the recent advances in bioflocculation based on algal-bacterial, algal-fungal, or algal-algal interactions within the framework of microalgae biomass harvesting for biofuel production. We also discuss recent advances using infochemicals and genetic engineering for the induction of bioflocculation.