A review on the sustainable procurement of microalgal biomass from wastewaters for the production of biofuels.

The feasibility of microalgal biomass as one of the most promising and renewable sources for the production of biofuels is being studied extensively. Microalgal biomass can be cultivated under photoautotrophic, heterotrophic, photoheterotrophic, and mixotrophic cultivation conditions. Photoautotrophic cultivation is the most common way of microalgal biomass production. Under mixotrophic cultivation, microalgae can utilize both organic carbon and CO2 simultaneously. Mixotrophic cultivation depicts higher biomass productivity as compared to photoautotrophic cultivation. It is evident from the literature that mixotrophic cultivation yields higher quantities of polyunsaturated fatty acids as compared to that photoautotrophic cultivation. In this context, for economical biomass production, the organic carbon of industrial wastewaters can be valorized for the mixotrophic cultivation of microalgae. Following the way, contaminants' load of wastewaters can be reduced while concomitantly producing highly productive microalgal biomass. This review focuses on different aspects covering the sustainable cultivation of different microalgal species in different types of wastewaters.