Microalgae-based biorefineries for sustainable resource recovery from wastewater

Extensive and improper utilization of water from industrial, municipal, and agricultural activities generate 380 trillion L/y of wastewater worldwide. Wastewaters from different sources contain enormous amounts of nutrients such as carbon, nitrogen, and phosphorus. Thus, the recovery of these nutrients via appropriate sustainable process becomes a necessity. Among various processes microalgae-based technologies has attracted considerable attention and its strategies for sustainable and low-cost treatment of wastewater has allowed removal of over 70% nutrient loads from the wastewater. After the treatment of wastewater, the harvested microalgae biomass contains value-added biomolecules which can used for bioenergy production and nanoparticle synthesis. At present, high operational costs represent a major limitation for the development of microalgae-based biorefineries. Thus, the main aim of the review is to provide the knowledge about the potential of low-cost microalgae-based integrated biorefinery for wastewater treatments and resource recovery. Also, this review provides the insight of microalgae biomass-based bioenergy products, nanoparticles synthesis their application within the concept of circular bioeconomy. Furthermore, this review also provides information on different established industries which used microalgae for wastewater treatment.