Microalgal Bioremediation of Environmental Pollutants: Mechanisms, Applications, and Challenges

Environmental pollution has a profound impact on environmental quality and poses substantial risks to human health. Industrial and agricultural activity generate large amounts of pollutants, which have direct and irreversible impacts on Earth’s ecosystems. In this scenario, microalgae-based bioremediation emerges. It is an environmentally friendly and effective alternative for mitigating the toxicity of various chemical pollutants and physical materials that are harmful to the environment. Through the mechanisms of biosorption, bioaccumulation, and biodegradation, microalgae are capable of removing these contaminants from wastewater while simultaneously generating value-added biomass. Its applications include the bioremediation of heavy metals, hydrocarbons, pesticides, pharmaceuticals, radionuclides, and even microplastics, reinforcing its versatility. However, much progress has already been made at laboratory and pilot scales; large-scale implementation faces bottlenecks that are difficult to overcome. In light of all this, microalgae offer a unique contribution compared to conventional approaches. Therefore, the primary objective of this chapter is to present an integrative perspective on the principles of the circular bioeconomy and the role of microalgae-based bioremediation. Its principles, foundations, mechanisms, and applications in the use of microalgae for pollutant removal will be discussed. Furthermore, case studies on industrial applications will be covered, along with the main factors influencing efficiency, technical and economic limitations, and future prospects.