Constructed wetlands for emerging contaminants removal: Current status of antibiotics, microplastics, and their effects on nutrient transformation processes

Emerging contaminants (ECs) have become a critical global concern due to their persistence, widespread occurrence, and potential risks to water quality and human health. Constructed wetlands (CWs) are increasingly recognized as a sustainable and nature-based wastewater treatment technology, offering advantages such as low capital investment, operational simplicity, and high pollutant removal efficiency. Despite this, the complex interactions between ECs and CWs—particularly the underlying removal mechanisms and their influence on nitrogen and phosphorus cycling—remain insufficiently understood. This review systematically elucidates the mechanisms governing EC removal in CWs and critically evaluates the impacts of antibiotics and microplastics (MPs) on nutrient transformation processes. The analysis reveals that substrate adsorption and microbial degradation represent the dominant pathways for EC removal. However, the presence of antibiotics and MPs can disrupt CW functionality by inhibiting plant uptake, suppressing microbial activity, altering microbial community composition, and impairing nitrogen-transforming enzyme activity. These effects are more significant for nitrogen removal, whereas the influence on phosphorus cycling remains understudied, underscoring an urgent need for further targeted research. By integrating recent advances, this review highlights the novelty of examining EC-nutrient interactions in CWs and emphasizes the importance of bridging this knowledge gap to optimize CW performance. Ultimately, CWs hold considerable promise as ecological treatment systems for EC-laden wastewater, but advancing their application requires a deeper mechanistic understanding of the coupled processes governing EC fate and nutrient dynamics.