Microalgae an ecofriendly and sustainable wastewater treatment option: Biomass application in biofuel and bio-fertilizer production. A review

Rapidly growing industrialization and depletion of non-renewable fossil fuel has led to finding alternative viable renewable resources to meet the growing energy demand with less carbon dioxide generation. The modern world energy strategy is based on cost-effective and green alternatives and microalgae cultivation have potential to meet these criteria. Microalgae has been identified as a promising and sustainable alternative for treating wastewaters along the production of valuable products. Microalgae with a short life span, high growth rate and high CO2 utilization efficiency is one of viable techniques of renewable resources to produce biomass using nutrients in wastewater. At current, the technology and cost are the main factors that limit the application at industrial scale, which needs an ideal downstream process to minimize the production cost. The simultaneous use of microalgae for wastewater treatment and biofuel production has made these challenges practicable and economically viable. Microalgae efficiency for ammonia, phosphorus and heavy metal removal along with biofuel and bio-fertilizer production is reviewed. It is also aimed to focus on recent advances in cultivation of microalgae in wastewater, the response of microalgae to different stresses and their effects on the quality and quantity of high-value products was investigated. The prospects for future research dealing with wastewater treatment and biofuel production on downstream processing is also suggested.