An optimized method for the bio-harvesting of microalgae, Botryococcus braunii, using Aspergillus sp. in large-scale studies

The use of fossil fuels which are derived from non-renewable sources has been linked to global warming, adverse human health effects and environmental pollution. Consequently, there is a need to develop alternative sources of fuel that are renewable and more environment-friendly. Biofuel (biodiesel), produced from microalgae such as Botryococcus braunii is an alternative energy source, that is renewable (because algae can be cultured as needed), more biodegradable with lower global warming potential compared to fossil fuels. However, the use of microalgae is hampered by high costs associated with the production and harvesting of microalgal biomass in large-scale studies. In this article; • A robust and cost-effective method was developed for harvesting B. braunii; • Optimized Aspergillus sp.: B. braunii ratio (1:40) was used to bio-flocculate up to 97% of cultured microalgae in both small and large-scale studies (250 L); • No damage to the harvested microalgal biomass (validated by pyrolysis) was observed with the harvested biomass being suitable for any desired downstream application.