Microalgae-based wastewater treatment: mechanisms of pollutant removal, key performance factors, and resource utilization of by-product proteins

A graphical summary of microalgae-based wastewater treatment, illustrating environmental factors, pollutant removal mechanisms, and high-value utilization of biomass. Environmental pollution and the growing demand for a high-quality ecological environment have become increasingly pressing global challenges. Among these, water pollution remains a major environmental issue closely linked to human development. Consequently, efforts are being made to develop efficient wastewater treatment technologies. Among them, microalgae-based wastewater treatment technology has garnered a lot of interest because of its benefits, which include low cost, high efficiency, environmental friendliness, and the capacity to concurrently create high-value products. This review systematically summarizes and analyzes the mechanisms and pathways by which microalgae remove phosphorus, nitrogen, and heavy metals from wastewater, elucidates the key environmental factors affecting treatment efficiency, and further explores the application potential of microalgal protein in the food sector, as well as the latest advances in the preparation of nitrogen-doped functional materials using microalgal biomass. Unlike previous reviews that primarily focused on biofuel production and feed applications, this paper highlights two emerging resource utilization pathways: protein utilization for the food industry and the development of nitrogen-doped functional materials. It aims to provide a theoretical framework for the high-value utilization and sustainable development of microalgal wastewater treatment technology.