Promising solutions to solve the bottlenecks in the large-scale cultivation of microalgae for biomass/bioenergy production.

Microalgae-based bioenergy has been long considered as a promising substitute to replace the fossil fuels at large-scale. After the decades of research, several bottlenecks remain to be overcome to make the large-scale production of microalgal bioenergy commercially viable. In this review, the bottlenecks that restrict the commercial production of microalgal bioenergy are summarized as “high cost” and “low efficiency” and then identified in detailed categories. Several solutions which aim to solve the bottlenecks are presented and discussed correspondingly. The solutions presented in this review including cultivating in wastewater, recycling water and nutrients, utilizing the whole biomass, selecting indigenous strains, cultivating mixed-species, supplementing low-cost organic substrates, mixing vertically in reactor, optimizing metabolic pathway and attaching the cells on suspended-solids. Furthermore, a novel system integrated with the solutions, which is combined with the wastewater treatment system and characterized as the mixed-species cultivation of wild-selected mixotrophic microalgal strains in suspended-solid phase bioreactor based on low-cost substrate, is proposed to promote the scale-up of the microalgal cultivation for bioenergy production. [ABSTRACT FROM AUTHOR]