Nature-based wastewater solutions: a comprehensive review of algae–wetland integration for nutrient and microplastics removal

With the increasing global demands and unrestrained consumerism, nutrient and microplastic (MP) pollution have become prevalent and emerged as twin threats to the aquatic ecosystems. Plastic production has soared to new heights—bringing with it a critical threat known as microplastic pollution, contaminating water bodies worldwide. MPs have been reported at multiple biological levels, from phytoplankton cells to tissues and organs in higher organisms, including humans. Alongside this, nutrient pollution represents another major stressor, arising due to the presence of excess nitrogen in water. Together, these dual threats highlight the urgent need for sustainable treatment approaches. In response, this study explores the treatment method entailing algae-constructed wetlands (A-CWs) systems and the various mechanisms for the removal of nutrients and MPs in aquatic ecosystems. The use of algae-based systems has been explored in relation to nutrients and carbon sequestration, supplementing the treatment of wastewater. Furthermore, this study summarizes the various types of wetlands and algae along with their mechanisms and configurations of A-CWs systems. It offers valuable insights regarding the application of viable solutions that can improve the water quality and promote environmental sustainability. Findings from the study indicate that A-CWs are very efficient in the removal of nitrogen, phosphorus, and MPs. These hybrid systems apply diverse mechanisms such as algal uptake, biofilm formation, sedimentation, and adsorption. Additionally, A-CWs can enhance carbon sequestration and offer low-energy and decentralized treatment options. However, scalability challenges require innovation in smart system configurations, genetic engineering, and resilient algal consortia.