Bio-based flocculants for sustainable harvesting of microalgae for biofuel production. A review

Christiana N. Ogbonna and Emeka G. Nwoba

Renewable and Sustainable Energy Reviews, 2021, vol. 139, issue C

Abstract: Energy is indispensable to human existence and sustains economic and individual activities globally. The rising environmental challenges of global warming and other climate changes due to increasing dependence on fossil fuels (coal, petroleum, natural gas) as the primary energy source requires innovation away from carbon-based fossil fuel sources. Hence, the development of renewable and low-emission energy sources becomes imperative to guarantee sustainable economic and human population growth and fuel security. In this context, microalgae biofuels are increasingly appreciated as viable alternative to fossil-based fuels because their biomass can be transformed into various clean fuel commodities such as biodiesel, biogas, and bioethanol in an environmentally-friendly and sustainable manner. However, high energy and financial costs of harvesting microalgal biomass for biofuel production constitute a substantial bottleneck in the industry. Bio-based flocculation methods have recently received increased research attention due to their high efficiency, sustainability, and environmentally-friendly attributes. In this review, the feasibility and performance of bio-based technologies for large-scale, cost-effective and sustainable harvesting of microalgal biomass for biofuel production were evaluated. The review shows that the harvesting efficiencies of bio-based processes are not significantly different from those achieved with energy-intensive traditional biomass separation methods such as centrifugation and membrane filtration. Harvested biomass met the moisture content metrics for biofuel feedstocks. The utilization of natural coagulants in algal biomass recovery is associated with low energy consumption, low environmental impacts and reduced effect on the chemistry of recycled medium. Production of recombinant bioflocculants are emerging but the application in algal biomass harvesting is yet to be reported. Bioflocculation approaches provide opportunities for the integration of photosynthetic biorefineries with bioremediation of wastewaters, and this enhances the potential of microalgae biotechnology for biofuel production.

Keywords: Bio-based flocculants; Biofuels; Biomass recovery; Flocculation; Microalgae; Sustainability (search for similar items in EconPapers)
Date: 2021
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Citations: View citations in EconPapers (7)

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DOI: 10.1016/j.rser.2020.110690

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