Microalgae-based biofuels, resource recovery and wastewater treatment: A pathway towards sustainable biorefinery

[Display omitted] •Microalgae-based biofuels, resources recovery and wastewater treatment are critically reviewed.•Various process routes are evaluated for microalgae cultivation/harvesting and biomass to biofuels.•Pathway towards sustainable biorefinery is proposed.•Commercial status and techno-economic analysis is presented.•Challenges and future research directions of microalgae-based resource recovery and wastewater treatment are identified. Intense utilization of natural fuel resources is threatening the global environment and societal sustainability. It triggers up the need for finding environmental-friendly and sustainable sources of energy. In this perspective, microalgae have emerged as a potential alternative. Microalgae are featured with distinct ability to provide ecological services and respond to the sustainability challenges simultaneously. Microalgae can fix atmospheric CO2, valorize waste resources and can produce a wide variety of bio-products. The promising features of microalgae pitch the idea of establishing a sustainable bio-refinery to draw multifaceted benefits and reinforce the objectives of resource efficient bio-economy. Unfortunately, in the last few years, preferential studies have been carried out to assess the potential of microalgae-based integrated bio-refinery. This review critically discussed the recent developments, opportunities, and barriers in the microalgae bio-industry and wastewater treatment. Particularly, microalgae potentials for biofuels and resources recovery are addressed towards sustainable biorefinery. Moreover, techno-economic and commercial viability of microalgae-led bio-refinery is reviewed to drive this technology towards practicality.