Role of microalgae in circular bioeconomy: from waste treatment to biofuel production

The rapid increase in human population and industrialization have caused severe environmental impacts, such as the depletion of energy and water resources, increase in carbon emissions, and contamination of water bodies. Thus, innovative ways to reduce these issues are essential and also a challenge. In this regard, the circular bioeconomy model has attracted attention, since it aims the sustainable production, utilization of renewable resources, and conversion into value-added products. Microalgal biotechnology represents a promising approach to this concept. These microorganisms can convert nutrients from solid, liquid, and gaseous wastes into biomass with potential as a feedstock for obtaining bioproducts. The simultaneous or sequential extraction of these products in a microalgae-based biorefinery could be an alternative to improve the economic feasibility of the process. Hence, this review article highlights the application of microalgae to carry out waste treatment and produce biofuels and biofertilizers within the circular bioeconomy concept. The challenges and opportunities are also briefly addressed. Graphic abstract