Role of microalgae in circular economy

Linear- and fossil-dependent economic activities, urbanization, and population growth have increased the discharge of nutrients (nitrogen and phosphorus) to water bodies and carbon dioxide (CO2) to atmosphere alike. Considering the cost of conventional nitrogen production processes, declining global organic phosphorus reserves, and the burden of climate change on economies, leaking nutrients, and CO2 are not only environmental, but also economic challenges. Alternative processes circulating nutrients and carbon within the economy therefore bare a win–win potential. Furthermore, when integrated, the nutrient removal, CO2 sequestration, and biofuel production processes could address the challenges of linear economy around both waste management and fossil-based resource dependence. This approach would bring circularity to urban systems by (1) “disassembling” and “reconstructing” the wastewater nutrients and CO2 emissions and (2) producing renewable energy. This chapter discusses the role of microalgae within circular economy, emphasizing their potential as agents of both waste management and valorization.