Microalgae-Based Approaches for Sustainable Wastewater Treatment: Recent Progress and Insights into Biofilm Systems

Population growth has necessitated more stringent regulation of effluent wastewater quality to protect source water. Microalgae have been identified as an emergent technique to perform biological nutrient removal and address this concern. Microalgae have been found to effectively uptake constituents of concern through assimilatory pathways while simultaneously contributing to climate change mitigation measures through carbon sequestration. This review summarizes the fundamental biological and physiological characteristics of microalgae that can be leveraged for application in engineered systems to treat wastewater. The current state of both suspended and biofilm systems has been reviewed and their respective advantages and limitations have been evaluated. Emphasis has been placed on recent progress in algal biofilm systems, providing insight related to the factors that contribute to their development. The study of algal biofilm systems remains limited in part due to the complex interactions that influence their behaviors. Hence, this review interrogates the strategies employed for the start-up and operation of biofilm systems and offers future perspectives related to the factors that could potentially expedite biofilm formation and enhance system performance.